Patent Publication Number: US-11664750-B2

Title: Multispeed alternating current motor

Description:
RELATED APPLICATIONS 
     This application is a continuation of U.S. application Ser. No. 16/664,550, filed Oct. 25, 2019, entitled Multispeed Alternating Current Motor, which is a continuation of U.S. application Ser. No. 15/940,956, filed Mar. 29, 2018, entitled Multispeed Alternating Current Motor, now U.S. Pat. No. 10,461,671, issued Oct. 29, 2019, which takes priority to U.S. App. No. 62/478,588, filed Mar. 29, 2017, and entitled Multispeed Alternating Current Motor, the entire contents of which are incorporated herein by reference. 
    
    
     FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     COMPACT DISK APPENDIX 
     Not Applicable. 
     BACKGROUND 
     In view of the growing proliferation of environmentally friendly laws, enhancements to various classes of motors are required. For example, refrigeration fan motors in a low wattage range, e.g. 4 to 16 watts, used in both the commercial and residential refrigeration markets, have traditionally been low efficiency, such as around 12%-26% efficient. It would be desirable to provide technologies to address enhancements required in different classes of motors. 
     SUMMARY 
     In one aspect, a multispeed alternating current (AC) machine circuit is for an AC power source having a first side and a second side. The AC machine circuit includes two or more pairs of power switches, one or more windings, and a control circuit to close one pair of power switches to cause current to flow from a first side of the AC power source, through the one or more windings, to the second side of the AC power source and to close the other pair of power switches to cause current to flow from the second side of the AC power source, through the one or more windings, to the first side of the AC power source. 
     In another aspect, a circuit is for a machine having alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The circuit comprises a winding with a start side and an end side, a first power switch connected between the first side and the winding start side, a second power switch connected between the second side and the winding start side, a third power switch connected between the first side and the winding end side, a fourth power switch connected between the second side and the winding end side, and a control circuit. The control circuit closes the first power switch and the fourth power switch and open the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and open the first power switch and the fourth power switch to cause current to flow from the second side to the first side. 
     In another aspect, a circuit is for a machine having alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The circuit comprises a first winding with a first start side and a first end side, a second winding with a second start side and a second end side, a first power switch connected between the AC power source first side and the first winding start side, a second power switch connected between the AC power source second side and the first winding start side, a third power switch connected between the AC power source first side and the first winding end side, a fourth power switch connected between the AC power source second side and the first winding end side, a fifth power switch connected between the AC power source first side and the second winding end side, a sixth power switch connected between the AC power source second side and the second winding end side, and a control circuit. The control circuit closes the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or closes the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. 
     In another aspect, a method is for a multispeed alternating current (AC) machine circuit for an AC power source having a first side and a second side. The method includes providing two or more pairs of power switches, providing one or more windings, and providing a control circuit to close one pair of power switches to cause current to flow from a first side of the AC power source, through the one or more windings, to the second side of the AC power source and to close the other pair of power switches to cause current to flow from the second side of the AC power source, through the one or more windings, to the first side of the AC power source. The method further includes providing components for the control circuit described herein and operating the circuit as described herein. 
     In another aspect, a method is for a circuit for a machine having alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The method comprises providing a winding with a start side and an end side, providing a first power switch connected between the first side and the winding start side, providing a second power switch connected between the second side and the winding start side, providing a third power switch connected between the first side and the winding end side, providing a fourth power switch connected between the second side and the winding end side, and providing a control circuit. The control circuit closes the first power switch and the fourth power switch and open the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and open the first power switch and the fourth power switch to cause current to flow from the second side to the first side. The method further includes providing components for the control circuit described herein and operating the circuit as described herein. 
     In another aspect, a method is for a circuit for a machine having alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The method comprises providing a first winding with a first start side and a first end side, providing a second winding with a second start side and a second end side, providing a first power switch connected between the AC power source first side and the first winding start side, providing a second power switch connected between the AC power source second side and the first winding start side, providing a third power switch connected between the AC power source first side and the first winding end side, providing a fourth power switch connected between the AC power source second side and the first winding end side, providing a fifth power switch connected between the AC power source first side and the second winding end side, providing a sixth power switch connected between the AC power source second side and the second winding end side, and providing a control circuit. The control circuit closes the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or closes the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. The method further includes providing components for the control circuit described herein and operating the circuit as described herein. 
     In another aspect, a divided phase windings circuit includes motor divided phase windings, a power switch circuit comprising at least one power switch and a direct current (DC) supply circuit all at a midpoint of the divided motor phase windings, and a non-collapsing DC power supply component to prevent the DC power supply from collapsing when the at least one power switch is on and conducting. The non-collapsing DC power supply component may include, for example, one or more of a tap from the motor divided phase windings electrically connected to the DC power supply, a secondary phase coil winding connected to the DC power supply to power the power supply, one or more resistors between the divided phase windings and the power switch circuit, one or more Zener diodes between the divided phase windings and the power switch circuit, and/or an electrical component to create a voltage drop between the motor divided phase windings and the power switch circuit to prevent the power supply from collapsing when the at least one power switch in the power switch circuit is on and conducting. 
     In one example, a phase windings circuit for a motor includes at least two phase windings forming one half of motor phase windings of the circuit and at least two other phase windings forming another half of the motor phase windings of the circuit. A direct current (DC) power supply is located at least approximately at a midpoint of the motor phase windings to receive alternating current (AC) power transferred from one or more of the phase windings and convert the AC power to DC power. A first stage power switch circuit comprises at least one power switch outside of the DC power supply and is electrically connected at least approximately at a midpoint between phase windings on each half of the circuit. A second stage power switch circuit comprises at least one other power switch outside of the DC power supply and is electrically connected at least approximately at the midpoint of the divided phase windings to receive AC power from the motor divided phase windings. A non-collapsing DC power supply component prevents the DC power supply from collapsing when the at least one power switch or the at least one other power switch is on and conducting. 
     In another example, a circuit for a motor comprises at least two phase windings forming one half of motor phase windings of the circuit and at least two other phase windings forming another half of the motor phase windings of the circuit. A direct current (DC) power supply at least approximately at a midpoint of the motor phase windings receives alternating current (AC) power transferred from one or more of the phase windings and converts the AC power to DC power. A first stage power switch circuit comprises at least one power switch outside of the DC power supply and is electrically connected at least approximately at a midpoint between the at least two of the phase windings on each half of the circuit. A second stage power switch circuit comprises at least one other power switch outside of the DC power supply and is electrically connected at least approximately at the midpoint of the phase windings to receive AC power from the motor phase windings. A motor controller controls the first stage power switch circuit and the second stage power switch circuit. The motor controller is electrically connected at at least one of (i) at least approximately at the midpoint of the phase windings and (ii) at least approximately at the midpoint between the at least two of the phase windings on each half of the circuit. A non-collapsing DC power supply component is connected to the DC power supply to prevent the DC power supply from collapsing when the at least one power switch or the at least one other power switch is on and conducting. 
     In another example, a motor has multiple motor phases (i.e. motor phase windings) and a supply line voltage through the phases. The motor phases are divided into four parts (fourths or quarters), with two motor phase windings forming one half of the motor phase windings of the circuit and two other motor phase windings forming the other half of the motor phase windings of the circuit. The motor controller for the motor and the power electronics for the motor are placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided phases and/or at a midpoint or center between two of the divided motor phases on each half of the circuit (e.g. “quarter-point”). The direct current (DC) power supply (e.g. for the electronics used in the motor controller) are also located between the divided phases, between the two halves of the divided phases and/or at a midpoint or center between two of the divided motor phases on each half of the circuit. The motor phases provide current limiting and the voltage drop from the line voltage supply lines to low voltage DC to the DC power supply, thereby reducing the DC power supply component count and allowing for the use of low voltage components for the DC power supply and for the motor controller. 
     In another example, the motor phases are divided into four parts (fourths or quarters), with two motor phase windings forming one half of the motor phase windings of the circuit and two other motor phase windings forming the other half of the motor phase windings of the circuit. The motor controller for the motor has two stages, with a first stage of the motor controller placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings, and a second stage of the motor controller placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. The power electronics for the motor have two stages, with a first stage of the power electronics placed at a midpoint or center between two of the divided motor phase windings on each half of the motor phase windings (e.g. “quarter-point”) and a second stage of the power electronics also placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. The direct current (DC) power supply (e.g. for the electronics used in the motor controller) are also located between the divided motor phase windings, between the two halves of the divided motor phase windings and/or at a midpoint or center between two of the divided motor phase windings on each half of the motor phase windings. 
     In another aspect, a method is for a machine having an alternating current (AC) power source with a first side (L 1 ) and a second side (L 2 ). The method comprises: at a motor controller for a circuit comprising a winding with a start side and an end side, a first power switch connected between the first side and the winding start side, a second power switch connected between the second side and the winding start side, a third power switch connected between the first side and the winding end side, and a fourth power switch connected between the second side and the winding end side: receiving a signal from an AC polarity detector and another signal from a Hall effect device and determining which of the power switches to open or close to obtain a proper direction of current flow through the winding based on the signal and the other signal. The motor controller closes the first power switch and the fourth power switch and opens the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and opens the first power switch and the fourth power switch to cause current to flow from the second side to the first side. 
     In another aspect, a method is for a machine having an alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The method comprises: at a control circuit for a circuit comprising a first winding with a first start side and a first end side, a second winding with a second start side and a second end side, a first power switch connected between the AC power source first side and the first winding start side, a second power switch connected between the AC power source second side and the first winding start side, a third power switch connected between the AC power source first side and the first winding end side, a fourth power switch connected between the AC power source second side and the first winding end side, a fifth power switch connected between the AC power source first side and the second winding end side, and a sixth power switch connected between the AC power source second side and the second winding end side: closing the first power switch and the sixth power switch and opening the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation. The control circuit closes the third power switch and the fourth power switch and opens the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation. The control circuit closes the first power switch and the fifth power switch and opens the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. The control circuit closes the second power switch and the fourth power switch and opens the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. 
     In another aspect, a method is for a machine having an alternating current (AC) power source with a first side (L 1 ) and a second side (L 2 ), two or more pairs of power switches, and one or more windings. The method comprises closing one pair of power switches by a control circuit to cause current to flow from a first side of the AC power source, through the one or more windings, and to the second side of the AC power source and closing another pair of power switches by the control circuit to cause current to flow from the second side of the AC power source, through the one or more windings, and to the first side of the AC power source. 
     In another aspect, a circuit is for a machine having an alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The circuit comprises a winding with a start side and an end side, a first power switch connected between the first side and the winding start side, a second power switch connected between the first side and the winding end side, a third power switch connected between the second side and the winding start side, a fourth power switch connected between the second side and the winding end side, an AC polarity detector to detect whether voltage from the AC power source is higher at the first side of the AC power source or the second side of the AC power source and output a signal indicating whether the voltage is higher at the first side of the AC power source or the second side of the AC power source, and a Hall effect device to detect a position of a rotor of the machine relative to a stator of the machine and output another signal indicating the position of the rotor relative to the stator. A motor controller receives the signal from the AC polarity detector and the other signal from the Hall effect device and determines which of the power switches to open or close to obtain a direction of current flow through the winding based on the signal and the other signal. In one aspect, the motor controller closes the first power switch and the fourth power switch and opens the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and opens the first power switch and the fourth power switch to cause current to flow from the second side to the first side. 
     In another aspect, a circuit is for a machine having an alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The circuit comprises a first winding with a first start side and a first end side, a second winding with a second start side and a second end side, wherein the second winding start side is connected to the first winding end side, a first power switch connected between the AC power source first side and the first winding start side, a second power switch connected between the AC power source first side and the first winding end side, a third power switch connected between the AC power source first side and the second winding end side, a fourth power switch connected between the AC power source second side and the first winding start side, a fifth power switch connected between the AC power source second side and the first winding end side, and a sixth power switch connected between the second side and the second winding end side. The circuit has a motor controller to control opening and closing the power switches to cause current to flow through the first winding and the second winding for fractional speed operation and to cause current to flow through the first winding and not the second winding for full speed operation, the motor controller further to close the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or close the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or close the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or close the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    depicts motor phase windings divided with a control circuit located at a mid-point in the motor phase windings. 
         FIG.  2    depicts a single phase electronically commutated motor (ECM). 
         FIG.  3    depicts a divided phase winding circuit. 
         FIG.  4    depicts a divided phase winding circuit with a tap from the divided phase winding coil to the direct current (DC) power supply. 
         FIG.  5    depicts a divided phase winding circuit with resisters between the divided phase windings and the power switch(es). 
         FIG.  6    depicts a divided phase winding circuit with a secondary coil. 
         FIG.  7    depicts a control of phase current direction during start up and continuous operation below synchronous speeds in a divided phase winding circuit. 
         FIG.  8    depicts a control of phase current direction at a synchronous speed of 1800 revolutions per minute (RPM) in a four pole divided phase winding circuit. 
         FIG.  9    depicts a control of phase current direction at a synchronous speed of 3600 revolutions per minute (RPM) in a two pole divided phase winding circuit. 
         FIG.  10    depicts DC supply storage capacitor charging periods. 
         FIG.  11    depicts a divided phase winding circuit with a secondary coil and one power switch. 
         FIG.  12    depicts a divided phase winding circuit with a secondary coil and one power switch. 
         FIGS.  13  and  13 A  depict a divided phase winding circuit with a secondary coil and one power switch. 
         FIG.  14    depicts a divided phase winding circuit with two power switches. 
         FIG.  15    depicts a divided phase winding circuit with one power switch. 
         FIG.  16    depicts a divided phase winding circuit with two power switches in series. 
         FIG.  17    depicts a divided phase winding circuit with a tap from the divided phase winding coil to the direct current (DC) power supply and two power switches in series. 
         FIG.  18    depicts a divided phase winding circuit with two power switches in parallel. 
         FIG.  19    depicts a divided phase winding circuit with a tap from the divided phase winding coil to the direct current (DC) power supply and two power switches in parallel. 
         FIG.  20    depicts a motor with a divided phase winding circuit having a primary AC phase winding and secondary winding to create a non-collapsing DC power supply. 
         FIG.  21    depicts a motor with a divided phase winding circuit having a primary AC phase winding and secondary winding to create a non-collapsing DC power supply wound on only one pole. 
         FIG.  22    depicts a motor with a divided phase winding circuit with a tapped primary phase winding to create a non-collapsing DC power supply. 
         FIG.  23    depicts a motor with a divided phase winding circuit with resisters to create a non-collapsing DC power supply. 
         FIG.  24    depicts a motor with a divided phase winding circuit with Zener diodes to create a non-collapsing DC power supply. 
         FIGS.  25 - 34    depict divided phase winding circuits with four coils and two stages for the power electronics. 
         FIG.  35    depicts a multispeed alternating current (AC) motor circuit for a motor. 
         FIG.  36 A  depicts a multispeed alternating current (AC) motor circuit for a motor. 
         FIG.  36 B  depicts an AC polarity detector for a multispeed alternating current (AC) motor circuit for a motor. 
         FIGS.  37 A- 37 B  depict a motor with a Hall effect device for a multispeed alternating current (AC) motor circuit for a motor. 
         FIGS.  38 - 42    depict voltages applied to windings for multispeed alternating current (AC) motor circuits for a motor. 
         FIG.  43    depicts a multispeed alternating current (AC) motor circuit for a motor with six switches. 
         FIG.  44    depicts a multispeed alternating current (AC) motor circuit for a motor with six switches. 
         FIG.  45    depicts a simplified multispeed alternating current (AC) motor circuit for a motor with four switches. 
         FIG.  46    depicts a simplified multispeed alternating current (AC) motor circuit for a motor with six switches. 
         FIG.  47    depicts a simplified multispeed alternating current (AC) motor circuit for a motor with eight switches. 
     
    
    
     DETAILED DESCRIPTION 
     New and useful circuits are disclosed that provide advantages over the prior art for controlling synchronous brushless permanent magnet motors. One embodiment of the present disclosure includes one or more circuits for an electronically commutated motor (ECM). Another embodiment of the present disclosure includes one or more circuits for a shaded pole motor. Another embodiment of the present disclosure includes one or more circuits for other types of motors. 
     In one aspect, a motor has multiple motor phases (i.e. motor phase windings) and a supply line voltage through the phases. The motor phases are divided in half and both the motor controller for the motor and the power electronics for the motor are placed at a “mid-point” or “center point” in the supply line voltage between the divided phases. The direct current (DC) power supply (e.g. for the electronics used in the motor controller) are also located between the divided phases. The motor phases provide current limiting and the voltage drop from the line voltage supply lines to low voltage DC to the DC power supply, thereby reducing the DC power supply component count and allowing for the use of low voltage components for the DC power supply and for the motor controller. 
     Prior systems used a Zener diode or other voltage regulator located in series with a power switch and the motor phases, which limited the maximum power of the motor to the maximum wattage value of the Zener diode. Circuits in the present disclosure eliminate the Zener diode voltage regulator from the primary current path for the motor phases so that a Zener diode voltage regulator is not located in series with a power switch and the motor phases, which eliminates the need to lower the wattage specification otherwise needed for a Zener diode. Instead, the Zener diode or other voltage regulator is located in parallel with the power switch(es) in some embodiments of the present disclosure. 
     In another aspect, a motor has multiple motor phases (i.e. motor phase windings) and a supply line voltage through the motor phases. The motor phases are divided into four parts (fourths or quarters), with two motor phase windings forming one half of the motor phase windings of the circuit and two other motor phase windings forming the other half of the motor phase windings of the circuit. The motor controller for the motor and the power electronics for the motor are placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided phases and/or at a midpoint or center between two of the divided motor phases on each half of the circuit. The direct current (DC) power supply (e.g. for the electronics used in the motor controller) are also located between the divided phases, between the two halves of the divided phases and/or at a midpoint or center between two of the divided motor phases on each half of the circuit. The motor phases provide current limiting and the voltage drop from the line voltage supply lines to low voltage DC to the DC power supply, thereby reducing the DC power supply component count and allowing for the use of low voltage components for the DC power supply and for the motor controller. 
     In one example, the motor phases are divided into four parts (fourths or quarters), with two motor phase windings forming one half of the motor phase windings of the circuit and two other motor phase windings forming the other half of the motor phase windings of the circuit. The motor controller for the motor has two stages, with a first stage of the motor controller placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings, and a second stage of the motor controller placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. The power electronics for the motor have two stages, with a first stage of the power electronics placed at a midpoint or center between two of the divided motor phase windings on each half of the motor phase windings (i.e. “quarter-point”) and a second stage of the power electronics also placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. The direct current (DC) power supply (e.g. for the electronics used in the motor controller) is also located between the divided motor phase windings, between the two halves of the divided motor phase windings and/or at a midpoint or center between two of the divided motor phase windings on each half of the motor phase windings. 
     For example, the DC power supply is located with the first stage when the DC power supply powers the first stage motor controller at the “quarter-point.” However, the DC power supply conceptually may be considered to be at a “mid-point” of the motor phase windings because when the first stage (stage 1) power electronics are energized and the second stage (stage 2) power electronics are not energized, the DC power supply is in the middle of the active coils (active motor phase windings) and the other two motor phase windings (coils) are not active at that time. The two active coils are current limiting. When the second stage is energized while the first stage is energized, the first stage coils are in parallel with the coils in the second stage. 
     Circuits in the present disclosure eliminate the need for an opto-isolator to allow switching between sensing/control electronics of a motor controller and a power switch of the motor controller. Prior systems had two neutral reference values, one for sensing/control electronics and one for a power switch. 
     Circuits in the present disclosure have improved line phase angle detection, eliminating the need for a precision resistance bridge linked to the input of an opto-isolator. Thus, the circuits of this aspect have more accurate line phase angle detection. 
     Circuits in the present disclosure reduce different electrical neutral values for the power switches and motor controller to one value. This guarantees that the power switch(s) of the circuits with this aspect will reliably transition from completely “off” to fully saturated. 
     Prior systems that included two switches have a difficult time turning one switch off completely for one half of an AC cycle. Circuits in the present disclosure place one or more switches outside of a DC power supply and motor controller circuit, resulting in proper switching. 
     Each of these improvements not only increases the reliability of the operation of the motor controller, but also serves to improve the combined motor/motor controller efficiency. 
     The divided phase winding circuits in the present disclosure can be used in a variety of motors, such as DC brushless motors/electronically communicated motors (ECMs), shaded pole motors, other synchronous motors, permanent-split capacitor (PSC) motors, etc. 
     For example,  FIG.  1    depicts a motor  102  with divided motor phase windings  104 ,  106  and a motor control circuit  108  located at a mid-point  110  in the divided motor phase windings. The motor  102  includes a stator  112  and a rotor  114  mounted on a shaft  116 . The rotor  114  is mounted for rotation in a core structure, such as a laminated core structure or other core structure. The rotor  114  has a body portion, which is shown as cylindrical in shape. Around the periphery of the body are located arcuately shaped permanent magnetic portions. The magnetic portion has its north magnetic pole adjacent to the outer surface of the rotor, and the magnetic portion has its south magnetic pole located adjacent to outer periphery of the rotor  114 . One or more windings or pairs of windings are mounted on the connecting portion of the core structure. The motor  102  also includes a Hall Effect switching device, a portion of which extends to adjacent the periphery of the rotor  114  for responding to the magnetic polarity of the respective rotor magnetic portions. In the construction as shown, the Hall Effect switch is located adjacent the outer periphery of the magnetic portion during half of each revolution of the rotor  114  and adjacent the outer periphery of the magnetic portion during the remaining half of each revolution of rotor. 
     The motor  102  can operate below, at, or above synchronous speeds. This is due to the fact that fractions of half cycles can flow through the phase windings. 
     The divided phase winding circuit of  FIG.  1    includes input connections on leads L 1  and L 2  connected to a source of alternating current (AC) energy during operation, such as AC line voltage. The leads L 1  and L 2  are connected across a series circuit that includes divided phase windings  104 ,  106  shown connected in series across a control circuit  108 . For example, the control circuit  108  may include a full wave diode rectifier bridge circuit connected in series to the divided phase windings  104 ,  106  and a power switch(es) circuit having one or more switches or other power controllable switching devices connected to the output of the full wave diode rectifier bridge circuit. 
     The divided phase windings  104 ,  106  can be bifilar or lap wound. The alternating current power source has its lead L 1  connected to the start side S 1  of the first winding  104 . The other end of the winding  104 , labeled F 1 , is connected to one of the inputs of the control circuit  108 . The other input side of the control circuit  108  is attached to the start side S 2  of the second divided phase winding  106 , and the finish side of the same divided phase winding, labeled F 2 , is attached to the input lead L 2  of the AC power source. 
     As another example,  FIG.  2    depicts a single phase ECM  202  in which the motor phase windings are divided, and a motor controller (motor control circuit) is located at a mid-point in the divided motor phase windings. 
       FIG.  3    discloses a divided phase winding circuit  302  for dividing motor phase windings  304 ,  306  (also referred to as motor phases or phase coils herein) of a motor in half and placing both a motor controller  308  for the motor and power electronics for the motor, including the DC power supply  310  and a power switch(es) circuit  312  with one or more power switches, at a “mid-point” or “center point”  314  in the supply line voltage between the divided phases  304 ,  306 . In the example of  FIG.  3   , the motor phase winding is divided in half. Some variation from the half division is allowable, such as between zero and plus/minus 20% of the halfway point. 
     The divided phase winding circuit  302  of  FIG.  3    includes two divided phase windings  304 ,  306 , each connected to AC line voltage L 1  and L 2  respectively. A DC power supply  310  is electrically connected to the divided phase windings  304 ,  306 , such as at the finish side of the first phase winding  304  and the start side of the second phase winding  306 . The divided phase winding  304 ,  306  operates to lower the AC line voltage to a voltage compatible with the DC power supply  310 . Thus, the number of windings in the divided phase winding  304 ,  306  can be selected to reduce the AC line voltage received at L 1  and L 2  to a selected lower voltage to be received by the DC power supply  310 . The divided phase winding  304 ,  306  also operates to filter noise from the AC line voltage received at L 1  and L 2 . 
     The DC power supply  310  converts the low voltage AC power received from the divided phase windings  304 ,  306  to a DC voltage configured to power the DC powered components of the divided phase winding circuit, including the motor controller  308 . The DC power supply  310  then supplies power to the motor controller  308 . 
     The motor controller  308  controls the start-up and operation of the divided phase winding circuit  302 . For example, the motor controller  308  controls start-up, including where the motor is a synchronous motor. The motor controller  308  determines the location of the rotor relative to the stator. The motor controller  308  also determines and monitors the speed of the rotor, such as in revolutions per minute (RPMs), to determine operational parameters of the motor, such as when the motor has reached synchronous speed, and controls the motor based on the location of the rotor and/or speed of the motor. In one example, the motor controller  308  has a Hall effect switch and/or other rotation determining device to determine the position of the rotor and/or rotation counting or speed determining device to determine the speed of the rotor. 
     The power switch(es) circuit  312  includes one or more power switches, such as one or more metal-oxide-semiconductor field-effect transistors (MOSFETs), silicon-controlled rectifiers (SCRs), transistors, or other switches or switching devices. The one or more switches are on or off or one is on while the other is off. For example, in one half cycle of an AC cycle, a first power switch is on and conducting while the second switch is off and not conducting. In the other half cycle of the AC cycle, the second power switch is on and conducting while the first switch is off and not conducting. In circuits with one switch, the switch may be on and conducting or off and not conducting during one or more portions of the AC cycle. 
     The power switch(es) circuit  312  is isolated from (outside of) the DC power supply  310 , which makes the divided phase winding circuit  302  more stable than circuits having the power switch(es) circuit within (and not isolated from) the DC power supply. 
     When the power switch(es) of a circuit turn on, there is only a slight voltage drop through the power switch(es) due to the minor resistance of the power switch(es). Therefore, if the input voltage for the DC power supply is developed by connecting the DC power supply leads to both sides of a power switch (or power switches), this would result in the DC power supply collapsing (i.e. the DC voltage from the DC power supply reducing to a voltage level at or below the switch ‘on’ resistance times the current through the power switch(es), which is close to zero) when the power switch is in an ‘on’ state or not being able to receive power and power the DC components of the circuit. 
     For example, if the power switch is directly connected across the DC power supply or across the DC side of a bridge rectifier and if there are not one or more components in series with the power switch to create a voltage drop when the power switch is conducting or ‘on’, the conducting power switch ‘shorts out’ or connects together the positive and negative terminals of the bridge rectifier for the DC power supply, which collapses the DC voltage (causes the DC voltage to be reduced to a level at or below the ‘on’ resistance of the power switch times the current through the power switch, which is close to zero). Since the ‘on’ resistance of the power switch is extremely low or typically in the milliohms, the DC voltage is very close to zero. 
     The divided phase winding circuit  302  includes one or more non-collapsing DC power supply components  316 ,  318  (components to prevent the DC voltage from the DC power supply from being reduced to or below the switch ‘on’ resistance times the current through the power switch(es), which is close to zero), including voltage drop components or direct DC power supply powering components to create a non-collapsing DC power supply. Examples of non-collapsing DC power supply components  316 ,  318  include a tap from the primary phase winding  304 ,  306  electrically connected to the DC power supply  310 , a secondary phase coil winding connected to the DC power supply to power the power supply, resistors between the divided phase windings and the power switch(es) circuit  312 , one or more Zener diodes between the divided phase windings and the power switch(es) circuit, a non-saturated semiconductor or other resistive component between the divided phase windings and the power switch(es) circuit  312  where the resistance is high enough to create a significant voltage drop and where this voltage drop causes the DC power supply when the switch is ‘on’, or other components to create a voltage drop between the primary divided phase windings and the power switch(es) circuit to prevent the DC power supply from collapsing when the power switch(es) in the power switch(es) circuit is/are on and conducting. The divided phase winding circuit  302  therefore provides a constant flow of power regardless of whether the power switch(es) circuit is on and conducting or off and not conducting. 
     Many electronically controlled synchronous motors have circuits that detect the zero crossing of the AC voltage applied to the phase windings. This zero crossing detection circuit sends a signal to the motor controller  308  to determine when the motor is at synchronous speed. If the AC supply voltage has electrical noise riding on, usually due to other equipment operating on the same circuit, this electrical noise can cause the zero crossing detector to operate incorrectly affecting the control of the motor, which normally appears as acoustical noise in the motor. 
     In one example, the divided phase winding circuit  302  is part of a synchronous motor. The synchronous motor receives line power (that is, AC power with a current and voltage) at L 1  and L 2 . A synchronous motor using a divided phase winding using the associated circuit of the present disclosure does not rely upon detecting the zero crossing of the applied AC voltage to control the motor but rather detects the polarity of the voltage, i.e. whether the polarity L 2  is higher or less than L 1 , allowing for quiet operation even when electrical noise is present in the AC supply. 
     The DC power supply  310  in  FIG.  3    is electrically connected directly to the divided phase windings  304 ,  306 . Thus, the DC power supply  310  is powered by the divided phase windings  304 ,  306  regardless of the status of the power switch(es) circuit  312 . 
       FIG.  4    discloses another divided phase winding circuit  402  for dividing motor phase windings  404 ,  406  of a motor in half and placing both a motor controller  408  for the motor and power electronics for the motor, including the DC power supply  410  and a power switch(es) circuit  412  with one or more power switches, at a “mid-point” or “center point”  414  in the supply line voltage between the divided phases. The divided phase winding circuit  402  of  FIG.  4    includes a tap  416 ,  418  from the primary divided phase winding  404 ,  406  electrically connected to the DC power supply  410  to create a non-collapsing DC power supply (a DC power supply in which the DC voltage is not reduced to or below the power switch(es) circuit ‘on’ resistance times the current through the power switch(es) circuit, which is close to zero). 
     In some circuits, when the motor reaches synchronous speed, the one or more power switch(es) turn off and thereby cause the low voltage power to stop flowing to the motor controller. In one example, the path from one divided phase winding through the power switch(es) to another divided phase winding is shorted, such as at synchronous speed. This results in the DC power supply and motor controller no longer receiving the low power supply voltage from the phase windings, such as in the event there is no capacitor to hold a charge during the short or a capacitor that is present is not large enough to hold enough charge during the short. The circuit  402  of  FIG.  4    includes a tap  416 ,  418  from the coils of the phase windings  404 ,  406  to the DC power supply  410  so that the low voltage power supply flows directly from the phase windings to the DC power supply, bypassing the power switch(es) for the motor controller  408  (“divided motor phase controller”). The circuit  402  of  FIG.  4    thereby guarantees that the low voltage power supply is supplied to the DC power supply  410 , for example at synchronous speed. 
     In one example, a DC power supply  410  for a divided motor phase controller is formed by a Zener diode and a storage capacitor that receives power during a portion of an alternating current (AC) cycle when the power switch(es) are off. When the motor is operating at synchronous speed, the power switch(es) are continuously conducting. Therefore, the amount of voltage being supplied to the DC power supply is equal to the voltage drop across the switch(es), which can result in a low voltage when using low on resistance (RDS(on)) power MOSFETs. 
       FIG.  5    discloses another divided phase winding circuit  502  for dividing motor phase windings  504 ,  506  of a motor in half and placing both a motor controller  508  for the motor and power electronics for the motor, including the DC power supply  510  and a power switch(es) circuit  512  with one or more power switches, at a “mid-point” or “center point”  514  in the supply line voltage between the divided phases. The circuit  502  of  FIG.  5    includes resistors R 1  and R 2  between the motor phase windings  504 ,  506  and the power switch(es) circuit  512  to hold up and therefore maintain the low voltage power supply supplied from the phase windings to the DC power supply  510  and create a non-collapsing DC power supply (a DC power supply in which the DC voltage is not reduced to or below the power switch(es) circuit ‘on’ resistance times the current through the power switch(es) circuit, which is close to zero). The circuit of  FIG.  5    thereby maintains the low voltage power supply to the DC power supply  510 , for example at synchronous speed. 
       FIG.  6    discloses another divided phase winding circuit  602  for dividing motor phase windings  604 ,  606  of a motor in half and placing both a motor controller  608  for the motor and power electronics for the motor, including the DC power supply  610  and a power switch(es) circuit  612  with one or more power switches, at a “mid-point” or “center point”  614  in the supply line voltage between the divided phases. The primary divided phase winding  604 ,  606  limits the current that can flow to the DC power supply  610 , thereby eliminating the need for current limiting components that waste power. The divided phase winding circuit  602  of  FIG.  6    includes a secondary phase winding  616 ,  618  electrically connected to the DC power supply  610  to create a non-collapsing DC power supply (a DC power supply in which the DC voltage is not reduced to or below the power switch(es) ‘on’ resistance times the current through the power switch(es), which is close to zero). 
     In one example, the power switch(es) circuit  612  includes a Zener diode or other voltage regulator and a power switch in parallel. Whereas, prior systems included the power circuit in series with other components. Because the power switch is in parallel with the Zener diode and not in series, it can always be on. However, if the power switch is off, current can still flow through the Zener diode. 
     The circuit of  FIG.  6    includes one or more secondary coils (also referred to as a secondary winding)  616 ,  618  that provide a low voltage power supply to the DC power supply  610 , such as when the motor is at start-up. The one or more secondary coils  616 ,  618  also act as a high frequency noise filter to filter out high frequency noise from the low power voltage supplied to the DC power supply  610 . 
     The secondary winding  616 ,  618  may be distributed anywhere, such as evenly between the first and second divided phase windings  604 ,  606 , all on one pole, or unevenly between the first and second divided phase windings, such as a greater number of turns or coils on one secondary winding than another secondary winding. 
     In the example of  FIG.  6   , the divided phase winding circuit  602  can turn off the DC electronics, including the motor controller  608 , when the motor is on and at synchronous speed. Thus, the motor controller  608  of the divided phase winding circuit  602  determines the speed of the motor and whether the motor is or is not at synchronous speed. For example, 1800 RPM may be the synchronous speed for a motor with four stator poles (two north stator poles and two south stator poles). Every half AC cycle, power is supplied to one of the magnetic poles. Therefore, it takes two cycles to provide power to the four magnetic poles. Thus, the synchronous speed is 1800 RPM if the motor is synced to line AC. Similarly, the synchronous speed for an eight-pole stator would be 900 RPMs. 
       FIG.  7    depicts a control of phase current direction during start up and continuous operation below synchronous speeds in a divided phase winding circuit  702 . 
     As shown in  FIG.  7   , the current will always flow across both divided phase windings  704 ,  706  and the power switch(es) circuit  708  in the same direction. The divided phase windings  704 ,  706 , being in series with the power switch(es) circuit  708 , represent one winding with the power switch(es) circuit  708  placed at the mid-point or center point between the divided phase windings. The current and voltage applied to the divided phase windings will always be in the same direction through both coils, and the magnetic polarity of the divided phase windings will likewise be the same. 
     As discussed below, the control circuit may include a diode rectifier bridge circuit whose output is connected to one or more power switches. As shown in  FIG.  7   , if the output terminals of the diode bridge rectifier of the power switch(es) circuit  708  are shorted when the voltage on lead L 1  is positive, the current will only flow through the winding  704 ,  706  in one direction, but in half cycle increments. If the voltage across leads L 1  and L 2  is 60 cycles, then the outputs of the diode bridge rectifier circuit in the control circuit will be shorted only when lead L 1  is positive, and current will flow only in one direction and for 8 milliseconds. No current will flow for 8 milliseconds on the alternate half cycles. Then current would flow for another 8 milliseconds and so on. If the output of the diode bridge circuit of the control circuit is shorted when lead L 2  is positive, then power will flow in the same manner. If the shorting of the output of the bridge is accomplished selectively, that is based on the angular position of the magnetic rotor, continuous motor action will be produced. If the diode bridge rectifier circuit output in the control circuit is shorted for a fraction of a half cycle selectively based on the angular position of the magnetic rotor as described above, and only when lead L 1  is positive, then any desired speed can be accomplished including speeds higher than the synchronous speed. The characteristics of such a motor would be similar to a DC motor with pulsating current applied to the inputs. However, rather than having multiple power switching components achieve the switching of the divided phase windings, the divided phase winding circuit makes use of the fact that alternating current in conjunction with one power switching component can accomplish the switching. 
       FIG.  8    depicts an example of control of phase current direction at a synchronous speed of 1800 revolutions per minute (RPM) in a four pole divided phase winding circuit. At synchronous speed, the controlled phase is synchronized with the AC line input. 
       FIG.  9    depicts a control of phase current direction at a synchronous speed of 3600 revolutions per minute (RPM) in a two pole divided phase winding circuit. At synchronous speed, the controlled phase is synchronized with the AC line input. 
       FIG.  10    depicts an example of DC power supply storage capacitor charging periods in a divided phase winding circuit. Note the correlation to the wave form of  FIG.  7   . 
       FIG.  11    depicts a divided phase winding circuit  1102  with a secondary coil  1104 ,  1106  and one power switch  1108 . The primary divided phase winding  1110 ,  1112  limits the current that can flow to the DC power supply. 
     The control circuit  1114  controls switching for the power switch(es) circuit  1115  based on timing of the input frequency and rotor position. The control circuit  1114  controls the start-up and operation of the divided phase winding circuit. For example, the control circuit  1114  controls start-up, including where the motor is a synchronous motor. The control circuit  1114  determines the location of the rotor relative to the stator. The control circuit  1114  also determines and monitors the speed of the rotor, such as in revolutions per minute (RPMs), to determine operational parameters of the motor, such as when the motor has reached synchronous speed, and controls the motor based on the location of the rotor and/or speed of the motor. In one example, the control circuit  1114  has a Hall effect switch and/or other rotation determining device to determine the position of the rotor and/or rotation counting or speed determining device to determine the speed of the rotor. 
     In one example, the power switch(es) circuit  1115  includes a Zener diode  1116  or other voltage regulator and a power switch  1108  in parallel. Whereas, prior systems included the power switch in series with other components. Because the power switch  1108  is in parallel with the Zener diode  1116  and not in series, it can always be on. However, if the power switch is off, current can still flow through the Zener diode. 
     The circuit of  FIG.  11    includes one or more secondary coils (also referred to as a secondary winding)  1104 ,  1106  that provide a low voltage power supply to the DC power supply, such as when the motor is at start-up. The one or more secondary coils  1104 ,  1106  also act as a high frequency noise filter to filter out high frequency noise from the low power voltage supplied to the DC power supply. 
     The secondary winding  1104 ,  1106  may be distributed anywhere, such as evenly between the first and second divided phase windings  1110 ,  1112 , all on one pole, or unevenly between the first and second divided phase windings, such as a greater number of turns or coils on one secondary winding than another secondary winding. 
     The way that the coils are connected to the circuit via the diode bridge rectifier  1118  allow for current to flow through the coils in only one direction at any given time. 
     The improvements that have been made to this motor and controller greatly improve the DC logic power supply which enables a more reliable logic control circuit. Secondary coils  1104 ,  1106  are wound with the motor coils in a method that creates a transformer using the motor coils as the primary coils  1110 ,  1112 . The example of  FIG.  11    uses a 20:1 ratio. The example of  FIG.  11    includes 1000 turns per motor primary coil and 50 turns per secondary coil that are wound on the same stator pole. However, other turn ratios may be used, higher or lower. The ratio between the primary motor coils  1110 ,  1112  and secondary coils  1104 ,  1106  may change with AC input power and/or DC power requirements. This circuit not only isolates all DC circuitry from high voltages from the line, but also creates a non-collapsible DC power supply to the control circuit  1114  when power is applied to inputs L 1  and L 2 . 
     The power switch(es) circuit  1115  has a full wave bridge rectifier  1118  in addition to the MOSFET power switch  1108 . The full wave bridge rectifier  1118  guarantees that no negative voltage will be supplied to the drain (top) of the power switch  1108 . The full wave bridge rectifier  1118  also guarantees that no positive voltage will be supplied to the source (bottom) of the power switch  1108  so that current can only flow from the drain to the source of the power switch  1108  when biased by a positive voltage on the gate of the power switch  1108  via resistor R 1 . Simultaneously, as a positive rectified AC power supply is present at the drain of the power switch  1108 , the power switch  1108  is biased by the same voltage signal via resistor R 1 . Diode  1116  protects the gate of the power switch  1108  by guaranteeing that any voltage on the gate of the power switch  1108  will be greater than −0.7 VDC, as anything less could damage or destroy the power switch  1108 . Resistor R 11  and capacitor C 5  are used as a “snubber” to filter out transients or high frequency noise. R 11  and C 5  provide added protection for the MOSFET power switch  1108 , especially in noisy environments. 
       FIG.  12    depicts a divided phase winding circuit  1202  with a secondary coil  1104 ,  1106  and one power switch  1108 . The circuit of  FIG.  12    includes the same power switch(es) circuit of  FIG.  11    and the same secondary coils  1104 ,  1106 . In addition, the control circuit  1114 A of  FIG.  12    includes a logic control circuit  1204  to control operation of the motor, including through synchronous speed, a logic control shut off circuit  1206  to control when the power switch(es) circuit is turned off, and a non-collapsing DC power supply  1208  to supply DC power to the logic control circuit and login control shut off circuit. The logic control circuit  1204  and logic control shut off circuit  1206  may be configured as a single logic control circuit. 
     In one embodiment, one purpose of the divided phase windings circuit  1202  is to allow a motor to run synchronously to the AC power supply line frequency (for example, for a 4 pole motor, 60 Hz=1800 rpm and 50 Hz=1500 rpm). Without any control circuitry, the power switch(es) circuit would allow current to flow as if coil pairs L 1  and L 2  were shorted together through the power switch(es) circuit. The control circuitry turns the power switch(es) circuit off until the rotor is in the proper position compared to the line voltage. For this reason, in one aspect, the power switch(es) circuit is rated for the AC power supply line voltage. The control circuitry components can all be at the logic level voltage (VCC). 
     Logic power is supplied by secondary coils  1104 ,  1106  that are wound on the same poles as the primary motor coils  1110 ,  1112 . Secondary coils  1104 ,  1106  could be wound on any number of poles as long as the secondary power meets logic power requirements. In one example, the control circuit is only needed to start the motor and bring it to synchronous speed, and the logic control shut off circuit optionally is included to shut off the main control circuit. The logic control shut off circuit is optional. By shutting the control circuit off, the power switch(es) circuit will allow full line power to the motor minus any losses in the power switch(es) circuit. This will increase total efficiency and the life of components especially when the motor runs for long periods. 
       FIGS.  13  and  13 A  depict a divided phase winding circuit with a secondary coil and one power switch. The circuit has two AC supply line inputs L 1  and L 2 , which are connected to an AC power source during operation of the motor. 
     Power Switches Circuit 
     The power switch(es) circuit has a full wave bridge rectifier BR 1  and a MOSFET power switch Q 1 . The full wave bridge rectifier BR 1  guarantees that no negative voltage will be supplied to the drain (top) of the power switch Q 1 . The full wave bridge rectifier BR 1  also guarantees that no positive voltage will be supplied to the source (bottom) of the power switch Q 1  so that current can only flow from the drain to the source of the power switch Q 1  when biased by a positive voltage on the gate of the power switch Q 1  via resistor R 1 . A positive rectified AC power supply is present at the drain of the power switch Q 1 , the power switch Q 1  is biased by the same voltage signal via resistor R 1 . Diode D 5  protects the gate of the power switch Q 1  by guaranteeing that any voltage on the gate of the power switch Q 1  will be greater than −0.7 VDC, as anything less could damage or destroy the power switch Q 1 . Resistor R 11  and capacitor C 5  are used as a “snubber” to filter out transients or high frequency noise. R 11  and C 5  provide added protection for the MOSFET power switch Q 1 , especially in noisy environments. 
     DC Power Supply 
     As soon as power is applied to the motor and current is flowing through the motor phase windings (motor primary coils), there is power on the secondary windings (secondary coils) in the same manner as the operation of a transformer. The value of voltage on the secondary coils is directly proportional to the input voltage and the primary coils to secondary coils turn count ratio. Using the example in  FIG.  11   , if the input voltage to the primary coils is 120VAC and the turn count ratio from the primary coils to the secondary coils is 20:1, then the voltage on the secondary coils would calculate to approximately 6VAC minus any losses. Power from the secondary coils is supplied directly from the secondary coils to the DC power supply. The full wave bridge rectifier BR 2  rectifies the low voltage AC power supply from the secondary coils. The full wave bridge rectifier BR 2  can be a low power component based on the DC supply requirements. 
     Zener diodes Z 1  and Z 2  are connected in series with each other anode to anode, and each cathode is connected to the AC power supply inputs of the full wave bridge rectifier BR 2 . This method is used to protect the full wave bridge rectifier BR 2  from AC power supply inputs that could exceed maximum ratings for the component. The negative output from the full wave bridge rectifier BR 2  is connected to the circuit ground, which is also connected to the same ground as the power switch block. The positive output from the full wave bridge rectifier BR 2  is connected to the low drop-out regulator LDO 1  and capacitor C 1 . Capacitor C 1  is provided to smooth the rectified AC power supply signal going to the input of the low drop-out regulator LDO 1 . A bypass capacitor C 7  could be used on the output of the low drop-out regulator LDO 1  to help reduce noise on the positive DC rail (VCC). Also, a larger capacitor C 10  could be used on the output of the low drop-out regulator LDO 1  to smooth the positive DC rail and ensure power during some low voltage situations. C 7  and C 10  are not required but are provided to add reliability and protection for low voltage DC components, especially in a noisy environment. 
     Logic Control Circuit/Motor Controller 
     The logic control circuit (motor controller) controls switching for the power switch(es) circuit based on timing of the AC supply line input frequency and rotor position. Timing of the AC supply line input frequency is sensed using an AC buffer that consists of bi-polar junction transistors (BJTs) Q 2  and Q 3  and diodes D 6  and D 7 . Current to the AC buffer input is limited by a high value resistor R 3 . Diode D 6  ensures that the AC buffer input is not greater than the positive DC supply voltage. Diode D 7  ensures the AC buffer input is greater than −0.7 volts referenced to the DC supply ground. 
     When the input to the AC buffer is logic high, BJT Q 2  is biased, and the output of the AC buffer is also logic high. When the input to the AC buffer is logic low, BJT Q 3  is biased, and the output of the AC buffer is logic low. The output of the AC buffer is connected to a filter consisting of capacitor C 6  and resistor R 13 . The filter is not required but provides protection and reliability in noisy environments. 
     Rotor magnet polarity is sensed using Hall-effect switch IC 1 . Though, another switch or sensing device may be used to sense rotor magnet polarity and/or rotor position and/or determine speed and/or determine rotor revolutions. The Hall-effect switch IC 1  is an open-collector output and therefore requires a pull-up to the positive DC rail (VCC). Resistor R 2  provides the pull-up required for the open-collector output. 
     The output of the Hall-effect switch IC 1  and the output of the AC buffer are compared using a single circuit logic XOR IC 2 . The output of the XOR IC 2  is the difference between the Hall-effect switch IC 1  and the AC buffer, which will bias MOSFET power switch Q 1  of the power switch(es) circuit. When the Hall-effect switch IC 1  output is logic low, the power switch Q 1  will only be biased when the AC supply input L 1  to the motor is negative. When the output of the Hall-effect switch IC 1  is logic high, the power switch Q 1  will only be biased when the AC supply input L 1  to the motor is positive. During motor start up, there can be multiple input AC cycles where either only the positive or only the negative inputs from AC supply input L 1  will pass through the power switch Q 1 . 
     Using the power switch Q 1 , waveforms can be “chopped” or shut off at any time when the drain and gate voltage of the power switch Q 1  is above biasing voltage. For example, see  FIG.  7   . The gate of the power switch Q 1  is held logic low when the output of the XOR IC 2  is logic high by biasing BJT Q 4 . When BJT Q 4  is biased, any current flowing from resistor R 1  will bypass the gate of the power switch Q 1  and flow through BJT Q 4  from collector to emitter electrically connecting the gate of the power switch Q 1  to its source and will shut off the power switch Q 1 . 
     When the frequency of the Hall-effect switch IC 1  matches the frequency of the input AC supply, the motor is running synchronously. If the motor is running synchronously, the control circuit is not needed until either the motor falls out of sync or the motor is stopped and restarted. When the voltage regulator IC 3  senses synchronous speed or greater from the Hall-effect switch IC 1 , the output of the XOR IC 2  is held logic low via the open-collector output of the voltage regulator IC 3 . When the voltage regulator IC 3  senses a speed that is less than that of the input AC supply, the open-collector output of the voltage regulator IC 3  is off, which will leave the output of the XOR IC 2  unaffected. 
     This method ensures that when the motor is running at a synchronous speed, the power switch Q 1  is not shut off by the logic control. But, if the motor slows down below synchronous speeds, then the logic controller will control the motor timing as it does for start-up. Using this method improves overall motor efficiency and the expected lifetime of components in the circuit. 
     External components are used to set timing for the voltage regulator IC 3 . Resistors R 4 , R 5 , R 6  and R 7  may be 1% tolerance so that the voltage regulator IC 3  operates within accurate parameters. Capacitor C 1  operates in conjunction with the resistors R 6  and R 7  to set the frequency at which the open-collector output of the voltage regulator IC 3  will turn on. Capacitor C 3  is used for an internal charge pump in the voltage regulator IC 3 . Capacitor C 4  is used to AC couple the input to the voltage regulator IC 3  since the voltage regulator IC 3  will only detect frequencies that have a zero-voltage crossing. Resistor R 8  limits current to the AC couple capacitor C 4  at the input of the voltage regulator IC 3 . 
       FIG.  14    depicts a divided phase winding circuit with two power switches. 
       FIG.  15    depicts a divided phase winding circuit with one power switch. 
       FIG.  16    depicts a divided phase winding circuit with two power switches in series. Diodes D 1  and D 2  are 1N4003 diodes and diodes D 3  &amp; D 4  are 1N914 diodes. Transistors Q 3  and Q 4  are 2N3904. IC 1  is a Hall-effect switch/sensor. Diodes D 5  and D 6  are used to increase the current capacity for the internal diodes in switches Q 1  and Q 2  (d 1  &amp; d 2 ) if the phase current exceeds the internal diodes forward current rating. Capacitors C 2  and C 3  are used to create a ‘turn on’ delay for switches Q 1  and Q 2  to add additional charge time for capacitor C 1  if necessary to insure a solid 3.3 VDC or 5 VDC supply for Hall switch/sensor IC 1 , depending upon the device choice for Hall switch/sensor IC 1 . In prior systems, 5 VDC was necessary to switch on the logic level power MOSFET switch. Capacitors C 2  and C 3  are optional in one embodiment. 
     Diodes D 1 , D 2 , d 1 , and d 2  perform the rectification of the AC power for the DC power supply for Hall switch/sensor IC 1 . 
     Zener diode ZD 1  provides the voltage regulator for the Hall switch/sensor IC 1 &#39;s DC power supply. 
     RL provides current limiting for the DC power supply. In one example, it is set to approximately limit the current to 10 mA. The Hall switch/sensor IC 1  uses 6 mA of DC current, including the base drive current for the internal open collector output transistor. Additional DC current will be used to turn on switch Q 3  and is supplied through the pull up resistor R 3 . The collector to emitter current for switch Q 3  and the base and collector to emitter current for switch Q 4  is not supplied by the DC power supply but is supplied by the current through the motor phase windings. It is preferable to assure that transistors Q 3  and Q 4  turn completely ‘off’ at the proper times. In one embodiment that the switches turn fully ‘on’ or in saturation at the proper times for maximum operational efficiency. 
       FIG.  17    depicts a divided phase winding circuit with a tap from the divided phase winding coil to the direct current (DC) power supply and two power switches in series. 
       FIG.  18    depicts a divided phase winding circuit with two power switches in parallel. 
       FIG.  19    depicts a divided phase winding circuit with a tap from the divided phase winding coil to the direct current (DC) power supply and two power switches in parallel. 
       FIG.  20    depicts a motor  2002  with a divided phase winding circuit having a primary AC phase winding  2004  and a secondary winding  2006  (i.e. one or more secondary coils) to create a non-collapsing DC power supply. In the motor of  FIG.  20   , the secondary winding  2006  is wound on all poles. However, the secondary winding  2006  can be wound on just one pole, two poles, three poles, or another number of poles. The secondary winding is connected in series with the primary phase winding  2004  in the motor  2002  of  FIG.  20   . However, the secondary winding  2006  also may be connected in parallel or with a combination of both series and parallel. The motor of  FIG.  20    is a four pole permanent magnet synchronous motor. The synchronous speed for the motor when operating at 60 Hz AC is 1800 RPM. 
       FIG.  21    depicts a motor  2102  with a divided phase winding circuit having a primary AC phase winding  2104  and a secondary winding  2106  (i.e. one or more secondary coils) to create a non-collapsing DC power supply wound on only one pole. The motor  2102  of  FIG.  21    is a four pole permanent magnet synchronous motor. The synchronous speed for the motor when operating at 60 Hz AC is 1800 RPM. 
       FIG.  22    depicts a motor  2202  with a divided phase winding circuit with a tapped primary phase winding to create a non-collapsing DC power supply. The motor  2202  of  FIG.  22    is a four pole permanent magnet synchronous motor. The synchronous speed for the motor when operating at 60 Hz AC is 1800 RPM. 
     The motor has a stator  2204  with 4 poles  2206 - 2212  and a rotor  2214  with 4 magnets N, S, N, S  2216 - 2222  facing the stator. The motor  2202  has a shaft (center circle)  2224  and rotor back iron (the area between the shaft and the magnets)  2226 . The primary divided phase windings  2228 ,  2230  are connected to an AC power supply at L 1  and L 2 , respectively. A secondary winding  2232 ,  2234  is connected to the DC power supply  2236 . 
       FIG.  23    depicts a motor with a divided phase winding circuit  2302  with resisters  2304 ,  2306  between the divided phase windings  2308 ,  2310  and the power switch(es) circuit  2312  to create a non-collapsing DC power supply. The motor of  FIG.  23    is a four pole permanent magnet synchronous motor. The synchronous speed for the motor when operating at 60 Hz AC is 1800 RPM. 
       FIG.  24    depicts a motor with a divided phase winding circuit  2402  with Zener diodes  2404 ,  2406  between the divided phase windings  2408 ,  2410  and the power switch(es) circuit  2412  to create a non-collapsing DC power supply. The motor of  FIG.  24    is a four pole permanent magnet synchronous motor. The synchronous speed for the motor when operating at 60 Hz AC is 1800 RPM. 
     The circuits of  FIGS.  25 - 34    depict divided phase winding circuits that may be used with one or more motors, such as one or more motors described herein. These circuits include motor phase windings for a motor that are divided into four parts, with two motor phase windings forming one half of the motor phase windings of the circuit and two other motor phase windings forming the other half of the motor phase windings of the circuit. By adding a connection between two motor phase windings (coils) in each half of the motor phase windings from the motor controller/motor control circuit, the motor can operate using only 2 of the 4 coils for startup. This is beneficial for startup because it decreases overall motor coil impedance, which will increase current and increase torque. Since current rises, efficiency can be reduced to at or under a selected acceptable percentage. The divided phase winding circuits provide, in some embodiments, startup torque at low input voltages. 
     Referring to the circuit of  FIG.  25   , the divided phase winding circuit  2502  has four divided motor phase windings  2504 - 2510 . Two of the motor phase windings  2504 - 2506  form one half  2512  of the motor phase windings of the circuit  2502 , and two other motor phase windings  2508 - 2510  form the other half  2514  of the motor phase windings of the circuit. The motor controller  2516  for the motor has two stages, with a first stage (stage 1)  2518  of the motor controller placed at a “mid-point” or “center point”  2520  in the supply line voltage between the two halves  2512 - 2514  of the divided motor phase windings  2504 - 2510 , and a second stage (stage 2)  2522  of the motor controller placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. 
     The power electronics for the motor have two stages, with a first stage (stage 1) power switch(es) circuit/power electronics  2524  placed at a midpoint or center  2526 ,  2528  between two of the divided motor phase windings  2504 - 2506  and  2608 - 2610 , respectively, on each half  2512 - 2514  of the motor phase windings (i.e. “quarter-point”). The stage 1 power switch(es) circuit activates the first (L 1 ) and fourth (L 4 ) coils  2504 ,  2510 . The stage 1 power switch(es) circuit  2524  may be, for example, one or more switches, such as one or more MOSFETs or other switches, and is controlled by the stage 1 motor controller  2518 . 
     A second stage (stage 2) power switch(es) circuit/power electronics  2530  is placed at a “mid-point”  2520  in the supply line voltage between the two halves  2512 ,  2514  of the divided motor phase windings  2504 - 2510 . The stage 2 power switch(es) circuit  2530  activates the second (L 2 ) and third (L 3 ) coils  2506 - 2508 . The stage 2 power switch(es) circuit  2530  may be, for example, one or more switches, such as one or more solid state relays (SSRs), quad solid state relays (QSSRs), or other switches, and is controlled by the stage 2 motor controller  2518 . The direct current (DC) power supply  2532  (e.g. for the electronics used in the motor controller) is also located between the divided motor phase windings  2504 - 2510 , between the two halves  2512 - 2514  of the divided motor phase windings and/or at a midpoint or center  2526 - 2528  between two of the divided motor phase windings  2504 - 2506  or  2508 - 2510  on each half  2512 ,  2514  of the motor phase windings. 
     The divided phase winding circuit  2502  includes one or more non-collapsing DC power supply components  2534 ,  2536  (components to prevent the DC voltage from the DC power supply from being reduced to or below the switch ‘on’ resistance times the current through the power switch(es), which is close to zero), including voltage drop components or direct DC power supply powering components to create a non-collapsing DC power supply. Examples of non-collapsing DC power supply components  2534 ,  2536  include a tap from one or more of the primary phase windings  2504 - 2510  electrically connected to the DC power supply  2532 , a tap from the outer primary divided phase windings (coil L 1  and coil L 4 )  2504  and  2510  electrically connected to the DC power supply  2532 , a secondary phase coil winding connected to the DC power supply to power the power supply, a secondary phase coil electrically connected from the outer primary divided phase windings (coil L 1  and coil L 4 )  2504  and  2510  to the DC power supply  2532 , resistors between the divided phase windings and one or more of the power switch(es) circuits, one or more resistors between the first and second divided phase windings (coil L 1  and coil L 2 ) and one or more resisters between the third and fourth divided phase windings (coil L 3  and coil L 4 )  2506  and  2508  where the DC power supply also is electrically connected one on side between the first and second divided phase windings (coil L 1  and coil L 2 ) and one the other side between the third and fourth divided phase windings (coil L 3  and coil L 4 ), one or more Zener diodes between the divided phase windings and one or more of the power switch(es) circuits, one or more Zener diodes between the first and second divided phase windings (coil L 1  and coil L 2 ) and one or more Zener diodes between the third and fourth divided phase windings (coil L 3  and coil L 4 ) where the DC power supply also is electrically connected one on side between the first and second divided phase windings (coil L 1  and coil L 2 ) and one the other side between the third and fourth divided phase windings (coil L 3  and coil L 4 ), a non-saturated semiconductor or other resistive component between the divided phase windings and one or more of the power switch(es) circuits (e.g. in place of the one or more resisters or diodes above) where the resistance is high enough to create a significant voltage drop and where this voltage drop causes the DC power supply when the switch is ‘on’, or other components to create a voltage drop between the primary divided phase windings and one or more of the power switch(es) circuits to prevent the DC power supply from collapsing when the power switch(es) in the power switch(es) circuit is/are on and conducting. The divided phase winding circuit  2502  therefore provides a constant flow of power regardless of whether the power switch(es) circuit is on and conducting or off and not conducting. 
       FIGS.  26  and  27    depict examples of divided phase winding circuits  2602  and  2702  with one or more secondary coils (also referred to as a secondary winding) electrically connected to the DC power supply to power the DC power supply and create a non-collapsing DC power supply (a DC power supply in which the DC voltage is not reduced to or below the switch(es) ‘on’ resistance times the current through the power switch(es), which is close to zero). The one or more secondary coils provide a low voltage power supply to the DC power supply  2632 , such as when the motor is at start-up. The one or more secondary coils also act as a high frequency noise filter to filter out high frequency noise from the low power voltage supplied to the DC power supply. 
     Referring to  FIG.  26   , the divided phase winding circuit  2602  has four divided motor phase windings  2604 - 2610 . Two of the motor phase windings  2604 - 2606  form one half  2612  of the motor phase windings of the circuit  2602 , and two other motor phase windings  2608 - 2610  form the other half  2614  of the motor phase windings of the circuit. The control logic/motor controller  2616  for the motor has two stages, with a first stage (stage 1)  2618  of the motor controller placed at a “mid-point” or “center point”  2620  in the supply line voltage between the two halves  2612 - 2614  of the divided motor phase windings  2604 - 2610 , and a second stage (stage 2)  2622  of the motor controller also placed at a “mid-point” or “center point” in the supply line voltage between the two halves of the divided motor phase windings. 
     The power electronics for the motor have two stages, with a first stage (stage 1) power switch(es) circuit/power electronics  2624  placed at a midpoint or center  2626 ,  2628  between two of the divided motor phase windings  2604 - 2606  and  2608 - 2610 , respectively, on each half  2612 - 2614  of the motor phase windings (i.e. “quarter-point”). The stage 1 power switch(es) circuit  2618  activates the first (L 1 ) and fourth (L 4 ) coils  2604 ,  2610 . The stage 1 power switch(es) circuit  2624  may be, for example, one or more switches, such as one or more MOSFETs or other switches, and is controlled by the stage 1 motor controller  2218 . In one example, the stage 1 power switch(es) circuit  2618  includes one or more Zener diodes or other voltage regulator and a power switch in parallel. Whereas, prior systems included the power circuit in series with other components. Because the power switch is in parallel with the one or more Zener diodes and not in series, it can always be on. However, if the power switch is off, current can still flow through the Zener diode. 
     A second stage (stage 2) power switch(es) circuit/power electronics  2630  is placed at a “mid-point”  2620  in the supply line voltage between the two halves  2612 ,  2614  of the divided motor phase windings  2604 - 2610 . The stage 2 power switch(es) circuit  2630  is electrically connected to the inner primary divided phase windings (second coil L 2  and third coil L 3 )  2606  and  2608 , and the stage 2 power switch(es) circuit activates the second (L 2 ) and third (L 3 ) coils. The stage 2 power switch(es) circuit  2630  may be, for example, one or more switches, such as one or more solid state relays (SSRs), quad solid state relays (QSSRs), or other switches, and is controlled by the stage 2 motor controller  2618 . 
     In one example of  FIG.  26   , the divided phase winding circuit  2602  can turn off one or more of the DC electronics, such as stage 1 of the motor controller  2618 , when the motor is on and at synchronous speed. Thus, stage 1 of the motor controller  2618  determines the speed of the motor and whether the motor is or is not at synchronous speed. For example,  1800  RPM may be the synchronous speed for a motor with four stator poles (two north stator poles and two south stator poles). Every half AC cycle, power is supplied to one of the magnetic poles. Therefore, it takes two cycles to provide power to the four magnetic poles. Thus, the synchronous speed is 1800 RPM if the motor is synced to line AC. Similarly, the synchronous speed for an eight-pole stator would be 900 RPMs. 
     The direct current (DC) power supply  2632  (e.g. for the electronics used in the motor controller) is also located between the divided motor phase windings  2604 - 2610 , between the two halves  2612 - 2614  of the divided motor phase windings and/or at a midpoint or center  2626 - 2628  between two of the divided motor phase windings  2604 - 2606  or  2608 - 2610  on each half  2612 ,  2614  of the motor phase windings. The primary divided phase winding  2604 - 2610  limits the current that can flow to the DC power supply  2632 , thereby eliminating the need for current limiting components that waste power. 
     The divided phase winding circuit  2602  of  FIG.  26    includes a secondary coils  2634 ,  2636  (also referred to as a secondary winding or secondary phase winding) electrically connected from or between the outer primary divided phase windings (coil L 1  and coil L 4 )  2604  and  2610  to the DC power supply  2632  to create a non-collapsing DC power supply (a DC power supply in which the DC voltage is not reduced to or below the switch(es) ‘on’ resistance times the current through the power switch(es), which is close to zero). The coils of the secondary phase winding  2634 ,  2636  provide a low voltage power supply to the DC power supply  2632 , such as when the motor is at start-up. The one or more secondary coils  2634 ,  2636  also act as a high frequency noise filter to filter out high frequency noise from the low power voltage supplied to the DC power supply  2632 . The secondary coils  2634 ,  2636  may be distributed anywhere, such as evenly between the first and fourth divided phase windings  2604 ,  2610 , on one or more of the first, second, third, and fourth divided phase windings  2604 - 2610 , all on one pole, or unevenly between the first and second divided phase windings, such as a greater number of turns or coils on one secondary winding than another secondary winding. 
       FIG.  27    depicts a divided phase circuit  2702  similar to the divided phase winding circuit  2602  of  FIG.  6   . However, the divided phase circuit  2702  of  FIG.  27    depicts a full bridge rectifier, MOSFET switch, and diode for the stage 1 power switch(es) circuit  2624 A. The divided phase circuit  2702  also depicts particular values for some components, including 435 turns, 30AWG for the divided phase windings (coils)  2604 A- 2610 A, and 70 turn, 30AWG for the secondary coils  2634 A- 2336 A. 
     Referring still to  FIGS.  26  and  27   , in one aspect, the stage 1 power switch(es) circuit  2630  is only operational during startup. When the motor reaches synchronous speed, the control logic/motor controller  2616  turns the stage 1 power switch(es) circuit  2624  off and turns the stage 2 power switch(es) circuit  2630  on. The stage 1 motor controller  2618  controls which direction current flows through the coils based on the rotor position. In one example, more precise switching time is a factor for startup. The stage 2 power switch(es) circuit  2630  is either on or off and does not use rotor position to determine the direction of current flow. 
     As shown in the example in  FIGS.  26  and  27   , the stage 1 power switch(es) circuit  2624  is connected between an outer phase winding (coil L 1 )  2504  and inner phase winding (coil L 2 )  2506  on one side  2512  of the circuit and between the other outer phase winding (coil L 5 )  2510  and other inner phase winding (coil L 3 )  2508  on one side  2514  of the circuit. The stage 1 power switch(es) circuit  2624  completes a current path for the two outer phase windings (coil L 1  and coil L 4 )  2604 ,  2610 . The phase windings  2604 ,  2610  can be configured in several different ways to fit the needs of the motor application. The stage 1 power switch(es) circuit  2624  could also be configured to energize three of the phase windings  2604 - 2610  or just one of the phase windings to suit startup torque and power requirements. 
     When the stage 1 power switch(es) circuit  2624  turns off and the stage 2 power switch(es) circuit  2630  turns on, the current path for all four phase windings  2604 - 2610  is completed. Since the stage 2 power switch(es) circuit  2630  has a slower switching speed than the stage 1 power switch(es) circuit  2624  at startup, a component such as a relay or a solid state relay can be used for the stage 2 power switch(es) circuit and require fewer parts than if a power switch like the MOSFET is used for the stage 2 power switch(es) circuit. 
     If low cost is a goal, it might be beneficial to build an equivalent circuit using cheaper discrete components. In one of the circuits described below, the use of discrete components performs well in voltage range, current range, voltage drop across, and switching speed. It can also be built for equal or less cost than a solid state relay that meets the same power requirements. 
       FIGS.  28  and  29    depict examples of active elements for the stage 1 and stage 2 power switch(es) circuits. For stage 1 (startup), the active elements for the stage 1 power switch(es) circuit  2602 A are depicted in  FIG.  28    and include a full wave bridge rectifier  2802  and a MOSFET  2804 . The stage 1 power switch(es) circuit  2602 A also has a Zener diode  2806  in parallel with the MOSFET  2804 . Current flows through the Zener diode  2806  when the FET  2804  is on and off. Phase windings (coils)  2604 A,  2610 A for stage 1 ( FIG.  28   ) are connected to the full wave bridge rectifier  2802  so that the motor will run balanced. Powering two adjacent phase windings (coils) may pull the rotor harder to one side and it could cause excessive stress to the circuit, motor structure, or both. Depending on how the poles are wound and how the poles align to the rotor, it may be necessary to configure different coils for startup since the most torque is present at startup. Phase windings (coils) connected in an unbalanced configuration at the highest motor torque could cause excessive stress to the circuit, motor structure, or both. For stage 2, the active elements for the stage 2 power switch(es) circuit  2630 A are depicted in  FIG.  29    and include an SSR or QSSR. Though, another relay or other switch may be used. 
       FIGS.  30 A- 30 B  depict another example of a divided phase winding circuit  3002 ,  3002 A for a motor in schematic form. The circuit has two line inputs LI 1  or Line_in 1  and LI 2  or Line_in 2 , which are connected to the AC power source during operation of the motor. Like the circuits of  FIGS.  25 - 29   , the circuits of  FIGS.  30 A- 30 B  include motor phase windings that are divided into four parts, with two motor phase windings L 1 , L 2  forming one half  3004  of the motor phase windings of the circuit and two other motor phase windings L 3 , L 4  forming the other half  3006  of the motor phase windings of the circuit. 
     It also includes one or more secondary phase coil windings L 1 - 1 , L 4 - 1  ( FIG.  30 A ) or L 1 - 1 , L 3 - 1  ( FIG.  30 B ) electrically connected to the DC power supply to power the power supply and create a non-collapsing DC power supply (a DC power supply in which the DC voltage is not reduced to or below the switch(es) ‘on’ resistance times the current through the power switch(es), which is close to zero). The one or more secondary phase windings (coils) (also referred to as a secondary winding) provide a low voltage power supply to the DC power supply, such as when the motor is at start-up. The one or more secondary phase windings (coils) also act as a high frequency noise filter to filter out high frequency noise from the low power voltage supplied to the DC power supply. The secondary winding may be distributed anywhere, such as evenly between the first (L 1 ) and fourth (L 4 ) divided phase windings, all on one pole, or unevenly between the first (L 1 ) and fourth (L 4 ) divided phase windings, such as a greater number of turns or coils on one secondary winding than another secondary winding. The secondary winding may be distributed anywhere, evenly or unevenly, between any of the first (L 1 ), second (L 2 ), third (L 3 ), and fourth (L 4 ) divided phase windings. 
     Stage 1 Power Switch(es) Circuit 
     The Power Switch block has a full wave bridge rectifier BR 1  and a MOSFET Q 1 . The full wave bridge rectifier BR 1  guarantees that no negative voltage will be supplied to the drain (top) of the MOSFET Q 1  and guarantees that no positive voltage will be supplied to the source (bottom) of the MOSFET Q 1  so that current can only flow from the drain to the source of the MOSFET Q 1  when biased by a positive voltage on the gate of the MOSFET Q 1  via a resistor R 1  or a separate gate driver circuit. In the example of  FIG.  31   , simultaneously as positive rectified AC voltage is present at the drain of the MOSFET Q 1 , the MOSFET Q 1  is biased by the same voltage signal via the resistor R 1 . The diode D 1  protects the gate of the MOSFET Q 1  by guaranteeing that any voltage on the gate of the MOSFET Q 1  will be greater than −0.7 VDC, as anything less could damage or destroy or degrade the MOSFET Q 1 . In the example described above, the gate is essentially driven by drain voltage. In that type of configuration above, when the MOSFET Q 1  is energized, it collapses the gate drive signal, causing the MOSFET Q 1  to operate as if at the highest resistance from the drain to the source (Rds (on)). Since the resistance is higher, the voltage drop across the MOSFET Q 1  also is higher, which is taken directly from the power to the motor divided phase windings (coils) (L 1 -L 4 ). Adding a simple gate driver circuit increases the voltage to the gate of the MOSFET Q 1  and decreases Rds (on). An example of a gate driver using discrete components as described herein is shown in  FIG.  32   . Resistors R 1  and R 12 , Zener diode Z 1 , and diodes D 1  and D 2  make up a simple gate driver. 
     Referring again to  FIGS.  30 A- 30 B , a capacitor could be connected from the gate of the MOSFET Q 1  to the source of the MOSFET Q 1  to help hold a DC voltage level. Since the inputs of the gate driver are connected to the other side of the motor divided phase windings (coils), there is a difference in voltage that is approximately equal to (Voltage Line in)/(number of active coils). In the example of  FIG.  32   , if Line In is 120 VAC, since there are 2 active coils that have equal values, the voltage at the inputs of the gate driver is approximately 120/2=60 volts each. 
     The Zener diode Z 1  will regulate higher voltages and should be a value within the MOSFET&#39;s range of normal operation. The Zener diode Z 1  will regulate the amount of voltage equal to the voltage rating of the Zener diode; voltages higher than the rated Zener diode voltage are dropped across the Zener diode. The Zener diode Zlcan act as a voltage regulator. In this case, the voltage is regulated to be within the operating voltage of the MOSFET Q 1 . 
     In a configuration like the example of  FIG.  31   , a voltage drop across the MOSFET Q 1  may be about 5 volts or just enough to keep the MOSFET Q 1  biased. In the example of  FIG.  32   , the voltage drop across the MOSFET Q 1  may be less than 1 volt. 
     Stage 2 Power Switch(es) Circuit 
     The purpose of the stage 2 power switch(es) circuit is to run the motor in the most efficient way possible. Since stage 2 is rarely required to switch off and on or on and off within 1 input cycle, it can be designed to operate very simply. The only input needed from the stage 1 control logic/motor controller is a synchronous shut down input, SYNC SD. The SYNC SD input is used to shut down the stage 1 MOSFET Q 1  by pulling its gate to its source. The SYNC SD input also is used to turn the stage 2 power switch(es) circuit on for as long as the motor speed is running synchronous to the input frequency. In the example circuit in  FIGS.  30 A- 30 B , the SYNC SD input is a logic high for startup. When the cycle time for the frequency on the input to the voltage regulator IC 2  on pin  1  matches the time constant set by capacitor C 4  and resistor R 7 , the SYNC SD input is pulled to a logic low through and open collector output. For as long as synchronous speed is sensed by the voltage regulator IC 2 , the SYNC SD input is logic low. If the motor is loaded heavily or for some other reason the motor “falls out of sync”, the SYNC SD input will switch back from logic low to logic high. Stage 2 (e.g. the stage 2 power switch(es) circuit) will shut off and Stage 1 (e.g. the stage 1 power switch(es) circuit) will operate until synchronous speed is sensed. Since Stage 1 needs a logic high on the SYNC SD input to operate, and Stage 2 needs a logic low on the SYNC SD input to operate, Stage 1 and Stage 2 cannot be energized simultaneously in the examples of  FIGS.  30 A- 30 B . 
       FIG.  33    depicts a version of the stage 2 power switch(es) circuit that uses an isolated input, triac output, solid state relay (SSR) SSR 1 . This configuration requires only 2 components. The anode of the SSR input LED is connected to a positive voltage VCC through a current limiting resistor R 2 . The cathode of the SSR input LED is connected to the SYNC SD input. When the SYNC SD input switches to a logic low, a path for current is completed through the input LED, and the SSR turns on. Likewise, when the SYNC SD input is a logic high, there is no path for current through the input LED, and the SSR turns off 
       FIG.  34    depicts a circuit that replaces an SSR of the power switch(es) circuit using discrete components. The circuit of  FIG.  34    operates very similar to the stage 1 power switch(es) circuit. One difference is that the power switch(es) circuit is normally off for stage 2 since a high value resistor R 14  is connected between the drain of the switch Q 2  and the base of the switch Q 6 . When there is a positive voltage on the drain of the switch Q 2 , the switch Q 6  is energized, which shorts the gate of the switch Q 2  to its source, turning the switch Q 2  off. Another difference is the isolated input to the power switch(es) circuit via isolator ISO 1 . The input to the isolator ISO 1  works the same as the input to the SSR (SSR 1 ) previously described, and the output is an open collector. When the SYNC SD input switches to a logic low, the output of isolator ISO 1  is energized, which switches the base of the switch Q 6  to its emitter, turning the switch Q 6  off. When the switch Q 6  is off, the switch Q 2  will operate when there is a positive voltage above the threshold on the gate of the switch Q 2 . Another difference is that the capacitor C 2  can be a higher value since the stage 2 power switch(es) circuit does not require as fast switching. Increasing the value of the capacitor C 2  will allow for a simpler version of a gate driver circuit (diode D 1  and resistor R 6 ). 
     In other embodiments, alternating current (AC) driven synchronous motors and associated control circuits and power switch(es) circuits for the AC synchronous motors achieve very high efficiency at multiple fixed speeds, including fully synchronous speed and fractions of that synchronous speed. The fully synchronous speed is determined by the frequency of the alternating current power source and the number of rotor poles and stator poles of the motor. The motor stator includes at least one phase winding. However, the motor stator may have multiple phase windings, such as in the above-embodiments. One or more additional phase windings, and additional control circuitry for the control circuit, may be added to optimize performance at one or more selected fractional speeds or other fractional speeds. 
       FIGS.  35 - 47    depict examples of a multispeed alternating current (AC) circuit for a machine, the machine including a motor and a generator. The example of  FIGS.  35 - 42    includes a single winding (W). Though, two, three, or more windings may be used for the multispeed AC machine circuit. For example,  FIGS.  43 - 44    depict an example of two windings. In another example,  FIG.  45    depicts an example of a simplified circuit with one winding. In another example,  FIG.  46    depicts an example of a simplified circuit with two windings. In another example,  FIG.  47    depicts an example of a simplified circuit with three windings. 
       FIG.  35    depicts an example of a single winding multispeed AC machine circuit  3502 . The multispeed AC machine circuit  3502  has four power switches Q 1 , Q 2 , Q 3 , and Q 4 , one stator winding Wa, an alternating current (AC) source  3504  with a first line voltage side L 1  at lead L 1  and a second line voltage side L 2  at lead L 2 , and a control circuit  3506 . 
     The stator winding Wa is connected (at point A  3508 ) on one side of the winding between two power switches Q 1  and Q 2  on one side of the multispeed AC machine circuit  3502  and (at point B  3510 ) on the other side of the winding between the other two power switches Q 3  and Q 4  on the other side of the multispeed AC machine circuit. Point A  3508  is the start side of the winding Wa, and point B  3510  is the end side of the winding. 
     In the example of  FIG.  35   , the power switches Q 1 , Q 2 , Q 3 , and Q 4  are bi-directional power switches allowing current to flow from L 1  to L 2  or from L 2  to L 1 . Power switch Q 1  connects point A  3508  to L 1 , and power switch Q 3  connects point A to L 2 . Power switch Q 2  connects point B  3510  to L 1 , and power switch Q 4  connects point B to L 2 . The power switches are operated in pairs, Q 1 /Q 4  and Q 2 /Q 3 , to control the direction of current flow through the winding Wa. 
     In the example of  FIG.  35   , the power switches Q 1 , Q 2 , Q 3 , and Q 4  are High Speed SSRs (QSSRs) that include a MOSFET and each have four diodes  3512 - 3518 ,  3520 - 3526 ,  3528 - 3534 , and  3536 - 3542 , respectively. The diodes  3512 - 3542  are configured as a full-wave bridge rectifier with the MOSFET shorting the positive output of the rectifier to the negative output. The diodes  3512 - 3542  ensure current flows in the correct direction through the power switches by blocking the current from flowing in the wrong direction. When the MOSFET is energized, AC current flows from one AC input of the rectifier to the output (other AC side) of the rectifier. For example, the diodes  3512  and  3518 ,  3520  and  3526 ,  3528  and  3534 , and  3536  and  3542 , allow current to flow from L 2  to L 1  through the power switches Q 1 , Q 2 , Q 3 , and Q 4 , respectively. The diodes  3514  and  3516 ,  3522  and  3524 ,  3530  and  3532 , and  3538  and  3540 , allow current to flow from L 1  to L 2  through the power switches Q 1 , Q 2 , Q 3 , and Q 4 , respectively. Other types of power switches may be used in other examples, such as a switching device or combination of switching devices that allow for the switching of alternating current, including metal-oxide-semiconductor field-effect transistors (MOSFETs), silicon-controlled rectifiers (SCRs), or transistors configured to operate as AC switches, for example when placed in series in opposite directions with diodes, or relays or any other combination of switches that can be configured for switching alternating current. 
     The control circuit  3506  controls operation of the multispeed AC machine circuit  3502 . The control circuit  3506  determines which one or more of the power switches Q 1 , Q 2 , Q 3 , and/or Q 4  to close to obtain the proper direction of current flow through one or more windings in the multispeed AC machine circuit  3502 . In one example, the control circuit  3506  opens power switches Q 1  and Q 4  and closes power switches Q 2  and Q 3  to cause current to flow from L 1  to L 2 . In another example, the control circuit  3506  opens power switches Q 2  and Q 3  and close power switches Q 1  and Q 4  to cause current to flow from L 2  to L 1 . 
     In one example, the control circuit  3506  includes a hardware processor with software executing one or more instructions stored on a non-transitory computer readable storage medium. In another example, the control circuit  3506  includes a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array signal (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or combinations thereof designed to perform the functions described herein. 
       FIG.  36 A  depicts an example of a control circuit  3506 A for a multispeed AC machine circuit  3502 . The control circuit  3506 A includes a direct current (DC) power supply  3602 , an alternating current (AC) polarity detector  3604 , a Hall effect device  3606 , and a motor controller  3608 . The motor controller  3608  can be replaced with a machine controller with the same components as the motor controller to control a generator. 
     The DC power supply  3602  converts the incoming AC power to a DC voltage configured to power the DC powered components in the control circuit  3506 A, such as the Hall effect device  3606  and the motor controller  3608 . The DC power supply  3602  then supplies power to the DC powered components in the control circuit  3506 A, such as the Hall effect device  3606  and the motor controller  3608 . In one example, the DC power supply  3602  includes an IC Offline Converter in a buck topology to convert power from the incoming AC power to low voltage DC power. This low voltage DC power is used to power, and supplied to, one or more DC powered devices in the control circuit  3506 A, such as the Hall effect device  3606  and the motor controller  3608 . 
     The AC polarity detector  3604  detects whether the voltage is higher at L 1  or L 2  and outputs a polarity signal indicating which of L 1  or L 2  has the higher voltage, such as indicating whether the voltage at L 1  is higher or lower than the voltage at L 2 . In one example, if the AC polarity detector  3604  detects the voltage at L 1  is higher than the voltage at L 2 , the AC polarity detector outputs a polarity signal that is high, meaning voltage on L 1  is higher than L 2 . If the AC polarity detector  3604  detects the voltage at L 1  is lower than the voltage at L 2 , the AC polarity detector outputs a polarity signal that is low, meaning voltage on L 1  is less than the voltage on L 2 . 
     In one example, as shown in  FIG.  36 B , the AC polarity detector  3604  includes two resistors  3610  and  3612  and a Zener diode  3614 . A first resistor  3610  is connected to L 1  on one side of the first resistor and connected to the cathode of the Zener diode  3614  on the other side of the first resistor. The anode of the Zener diode  3614  is connected to one side of the second resistor  3612 , and the other side of the second resistor is connected to L 2 . With this configuration, when the voltage on L 1  is higher than the breakdown voltage of the Zener diode  3614 , the Zener diode conducts, leaving a voltage drop across the Zener diode that is equivalent to the breakdown voltage of the Zener diode. This results in a polarity signal that is high and that corresponds to the voltage on L 1 . When the voltage on L 1  is less than the breakdown voltage of the Zener diode  3614 , the voltage drop across the Zener diode is closer to zero. This results in a polarity signal that is low and that corresponds to the voltage on L 1 . In an alternate embodiment, an op-amp is used in place of the two resistors  3610  and  3612  and a Zener diode  3614  for the AC polarity detector  3604 . 
     The Hall effect device  3606  senses the position of the rotor relative to stator and outputs one or more Hall Effect signals indicating the position of the rotor relative to the stator. In one example, the Hall effect device  3606  senses a polarity of a magnet of the rotor relative to a stator tooth. In this example, the Hall effect device  3606  outputs a high Hall Effect signal or a low Hall Effect signal that is determined by the polarity of the magnetic pole it is sensing. In this example, the Hall effect device  3606  outputs (1) a high Hall Effect signal indicating a north magnetic pole is facing the stator or (2) a low Hall Effect signal indicating a south magnetic pole is facing the stator. 
     In one example, the location of the Hall effect device  3606  relative to the stator provides a high output when the back electromotive force (BEMF) of the motor is high. The Hall effect device  3606  is then shifted 36 electrical degrees advanced on the BEMF. The BEMF is generated by the combination of the rotor magnets on the spinning rotor passing by the stator teeth with the windings. The BEMF is determined, in one example, by the speed of the rotor and the number of turns on each pole. 
     The motor controller  3608  determines which one or more of the power switches Q 1 , Q 2 , Q 3 , and/or Q 4  to close to obtain the proper direction of current flow through one or more windings in the multispeed AC machine circuit  3502 . In one example, the motor controller  3608  opens power switches Q 1  and Q 4  and closes power switches Q 2  and Q 3  to cause current to flow from L 1  to L 2 . In another example, the motor controller  3608  opens power switches Q 2  and Q 3  and close power switches Q 1  and Q 4  to cause current to flow from L 2  to L 1 . 
     In one example, the motor controller  3608  receives signals from the AC polarity detector  3604  and the Hall effect device  3606  to determine which one or more of the power switches Q 1 , Q 2 , Q 3 , and/or Q 4  to close to obtain the proper direction of current flow through one or more windings in the multispeed AC machine circuit  3502 . In this example, when the Hall Effect signal is high, current should be flowing through the winding Wa from point A  3508  to point B  3510 . 
     If the Hall Effect signal is high and the AC polarity detection signal is high, meaning the voltage on L 1  is higher than the voltage on L 2 , the motor controller  3608  will transmit signals to power switch pair Q 2 /Q 3  to open power switch pair Q 2 /Q 3  and transmit signals to power switch pair Q 1 /Q 4  to close power switch pair Q 1 /Q 4 . In this instance, the higher voltage is applied to point A  3508  of the winding Wa, and the lower voltage is applied to point B  3510  of the winding Wa to create current flow from point A  3508  to point B  3510  through the winding Wa. 
     If the Hall Effect signal is high and the AC polarity detection signal is low, meaning the voltage on L 1  is less than the voltage on L 2 , the motor controller  3608  will transmit signals to power switch pair Q 1 /Q 4  to open power switch pair Q 1 /Q 4  and transmit signals to power switch pair Q 2 /Q 3  to close power switch pair Q 2 /Q 3 . This still applies the higher voltage to point A  3508  of the winding Wa and the lower voltage to point B  3510  of the winding Wa to create current flow from left to right through the winding, which is the correct direction of flow when the Hall effect signal is high. 
     If the Hall Effect signal is low and the AC polarity detection signal is high, meaning the voltage on L 1  is higher than the voltage on L 2 , the motor controller  3608  will transmit signals to power switch pair Q 1 /Q 4  to open power switch pair Q 1 /Q 4  and transmit signals to power switch pair Q 2 /Q 3  to close power switch pair Q 2 /Q 3 . In this instance, the higher voltage is applied to point B  3510  of the winding Wa, and lower voltage is applied to point A  3508  of the winding Wa to create current flow from point B  3510  to point A  3508  through the winding Wa, which is the correct direction of flow when the Hall effect signal is low. 
     If the Hall Effect signal is low and the AC polarity detection signal is low, meaning the voltage on L 1  is less than the voltage on L 2 , the motor controller  3608  will transmit signals to power switch pair Q 2 /Q 3  to open power switch pair Q 2 /Q 3  and transmit signals to power switch pair Q 1 /Q 4  to close power switch pair Q 1 /Q 4 . This still applies the higher voltage to point B  3510  of the winding Wa and the lower voltage to point A  3508  of the winding Wa to create current flow from point B  3510  to point A  3508  through the winding Wa, which is the correct direction of flow when the Hall effect signal is low. 
     In one example, the motor controller  3608  includes a hardware processor with software executing one or more instructions stored on a non-transitory computer readable storage medium. In this example, the processor processes Hall effect signal and the AC polarity signal and creates one or more driving logic signals based on whether each of the Hall effect signal and the AC polarity signal is high or low, and the motor controller transmits the one or more driving logic signals to the power switches (as described above) to open and close the power switches. In one example, the motor controller  3608  includes logic in which the Hall effect signal and the AC polarity signal are XOR&#39;d together to create one or more driving logic signals based on whether each of the Hall effect signal and the AC polarity signal is high or low, and the motor controller transmits the one or more driving logic signals to the power switches (as described above) to open and close the power switches. 
     In another example, the motor controller  3608  includes a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array signal (FPGA) or other programmable logic device (PLD), discrete gate or transistor logic, discrete hardware components, or combinations thereof designed to perform the functions described herein. A hardware processor may be a microprocessor, commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of two computing components, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. 
       FIGS.  37 A- 37 B  depict an example of a placement of a Hall effect device  3606  of a control circuit  3506 A for a motor  3702 . The motor  3702  has a rotor  3704  and a stator  3706 . A tripod  3708  holds a rear bearing/shaft  3710  in place. A Hall effect device holder or mount  3712  is mounted to the tripod  3708 , and the Hall effect device  3606  is mounted on the Hall effect device mount. 
     The rotor magnets  3714 - 3724  are magnetized radially through the center of the magnet. The rotor magnets  3714 ,  3718 , and  3722  with the mark on top have a north pole on the outside diameter (OD) and a south pole on the inside diameter (ID). The rotor magnets  3716 ,  3720 , and  3724  with no marking have a south pole on the outside diameter (OD) and a north pole on the inside diameter (ID). 
     In the example of  FIGS.  37 A- 37 B , the Hall effect device  3606  is placed at an inner edge of the rotor magnets  3714 - 3724  so it detects a magnetic pole of the rotor magnets that is opposite of the magnetic pole facing the stator  3706 . In this example, the Hall effect device  3606  has two output signals: (1) a high output signal indicating a north magnetic pole is facing the stator  3706  or (2) a low output signal indicating a south magnetic pole is facing the stator. 
     Referring to  FIGS.  35 - 42   , the multispeed AC machine circuit  3502  can operate in three different modes: starting mode, full synchronous speed mode, and fractional speed mode. 
     Starting mode is used for start-up of the motor in which the multispeed AC machine circuit  3502  is used. Starting mode can be operated in multiple different ways, including pulse-width modulation, delayed firing angle with zero current shutoff, or using a second winding. The different starting modes are used to limit starting current and torque to provide smooth stable operation. 
     Pulse-width modulation (PWM) mode may be used, for example, in a multispeed AC machine circuit  3502  with one winding Wa, as seen in  FIG.  35   , or two, three, or more windings. Pulse-width modulation (PWM) mode is used to limit starting current and torque by reducing the RMS voltage applied to the winding(s) by switching the voltage on and off at a high frequency through the winding(s), for example winding Wa, in the multispeed AC machine circuit  3502 . To operate the PWM mode, the control circuit  3506  closes a pair of power switches, either (a) Q 1  and Q 4  or (b) Q 2  and Q 3 , to apply voltage to the winding(s), for example winding Wa. 
     The control circuit  3506  has a microcontroller that generates one or more PWM signals to one or more of the power switches Q 1 , Q 2 , Q 3 , and/or Q 4 . The PWM signals open or close the one or more of the power switches Q 1 , Q 2 , Q 3 , and/or Q 4 . For example, the control circuit  3506  transmits the PWM signals to the power switch pairs Q 1 /Q 4  or Q 2 /Q 3  as described herein to open or close the power switch pairs Q 1 /Q 4  or Q 2 /Q 3 . 
     The PWM signal has a duty cycle, which for example can be based on the amount of starting torque/current that is required to start the motor. For example, a compressor motor would require a higher duty cycle/starting torque than a fan motor to start. The control circuit  3506  continuously determines the actual duty cycle value and compares the actual duty cycle value to a desired duty cycle value. In this example, when the desired duty cycle is reached, if the power switch pair Q 1 /Q 4  is closed and the AC polarity detection signal is high, indicating that current is flowing from L 1  through the winding Wa from point A  3508  to point B  3510  out to L 2 , the control circuit  3506  opens power switch Q 4  and closes power switch Q 2 . This connects both point A  3508  and point B  3510  of winding Wa to L 1 . Since both sides of the winding Wa are connected to the same voltage source, there is no differential voltage applied to the winding. This allows current to continue to flow through the winding in the same direction Wa, while no voltage is applied to the winding Wa until the next PWM cycle is reached. Then, the control circuit  3506  opens power switch Q 2  and closes power switch Q 4 , thereby applying voltage to the windings again. Alternatively, if power switch pair Q 1 /Q 4  were closed when the AC polarity detection signal  3604  is low, indicating that current was flowing from L 2  through winding Wa from point B  3510  to point A  3508  and out to L 1 , and the desired duty cycle is reached, the control circuit  3506  would open power switch Q 1  and close power switch Q 3 . This allows current to continue to flow through the winding Wa in the same direction without voltage applied to the winding Wa. The current must always have a path to flow to operate the PWM without shut-off spikes. PWM may also be used in the other operating modes to limit peak currents. 
     In synchronous speed mode, the motor is operating at synchronous speed. Synchronous speed rotations per minute (RPM) can be determined by taking the line frequency in Hertz divided by the number of rotor pole pairs (1 north pole and 1 south pole is equal to 1 pole pair) and multiplied by 60, the number of seconds in a minute. For example a six pole motor (3 north poles and 3 south poles) running on a 60 Hz supply would have a synchronous speed of 1200 RPM because 60 Hz/3 pole pairs*60 sec=1200 RPM. In full synchronous speed mode, one pair of power switches Q 1 /Q 4  or Q 2 /Q 3  is left always closed and the other pair Q 2 /Q 3  or Q 1 /Q 4  is left always open allowing continuous alternating current flow through the winding Wa. 
     Delayed firing angle with zero current shutoff mode may be used in starting mode to limit starting current/torque and also in fractional speed mode, as shown in  FIG.  42   . Delayed firing angle with zero current shutoff entails waiting until the sine wave of the AC voltage is past a certain point before closing any power switches. For example, once voltage is at the peak of the sine wave, either power switch pair Q 1 /Q 4  or power switch pair Q 2 /Q 3  may be closed to allow current flow through the winding Wa. Once current flow through the winding Wa is at zero, the motor controller  3608  will open all power switches and wait until the next peak of the sine wave is reached before the motor controller will close any power switches. In this example, the effective RMS value of the applied voltage will be reduced to 50% of the line voltage because only the second half of the sine wave voltage is applied to the winding Wa. The effective RMS voltage applied to the winding Wa in this mode may be adjusted by how much of the sine wave voltage is applied to the winding. 
     Fractional speed mode is used when the motor is operating at less than full synchronous speed. Fractional speed mode may be operated multiple ways by the motor controller  3608 , including using the delayed firing angle with zero current shutoff to adjust the power applied to the winding Wa or adding additional windings and using a simplified circuit, as seen in  FIG.  44   , to operate at a fixed fractional speed. With the simplified circuit shown in  FIG.  44   , the additional winding increases the BEMF to reduce the current draw and improve performance. The motor controller  3608  controls the power switch pairs Q 1 /Q 6  and Q 3 /Q 4  based on the Hall effect device  3606  while leaving power switches Q 2 /Q 5  always open. When the Hall effect device  3606  has a high output, the motor controller closes power switch pair Q 1 /Q 6  and opens power switch pair Q 3 /Q 4  allowing current to flow from L 1  through windings Wa and Wb to L 2 . No zero current shut-off is required in this instance because once the current flow reaches zero, the power switch diodes block current flow from coming the reverse direction, from L 2  through the windings Wa and Wb to L 1 . If the Hall effect signal from the Hall effect device  3606  is low, the motor controller  3608  opens power switch pair Q 1 /Q 6  and closes power switch pair Q 3 /Q 4  allowing current flow from L 1  through windings Wa and Wb to L 2 . The simplified circuit effectively creates a reduced frequency supply that operates at half of the line frequency, as seen in  FIG.  41   . PWM mode may also be used for fractional speed mode but has additional losses due to the high frequency switching. 
       FIG.  38 - 43    depict voltage applied to the winding Wa in operational modes. 
       FIG.  38    depicts an example of how the input AC voltage may be applied to the winding Wa at low (fractional) speed. The voltage applied to the winding Wa may vary based on the starting mode used (e.g. pulse-width modulation, delayed firing angle with zero current shutoff, or using a second winding). 
       FIG.  39    depicts an example of the available voltage that may be applied to the winding Wa as the motor approaches synchronous speed. The control circuit  3506  may filter out the chopped waveforms by delaying turn-on of the line voltage or shutting off of the line voltage at zero current, as in delayed firing angle mode with zero current shut-off mode, until synchronous speed for the motor is reached. In the example in this figure all of the available voltage is being applied to winding(s) based on the BEMF polarity. 
       FIG.  40    depicts the voltage applied to the winding Wa while the motor is running at synchronous speed. Depending on the load on the motor, the multispeed AC machine circuit  3502  may operate in a full synchronous mode where one pair of power switches Q 1 /Q 4  or Q 2 /Q 3  is left always closed and the other pair of power switches Q 2 /Q 3  or Q 1 /Q 4  is left always open. For operation with loads requiring less torque than is applied in full synchronous mode, current may be limited by delaying the firing angle, using PWM, or adjusting the phase angle that voltage is applied in relation to rotor position, which is similar to the starting mode. 
       FIG.  41    depicts an example of operation in fractional speed mode. The control circuit selectively skips half cycles or portions of half cycles of the AC input voltage in order to generate an effective reduced frequency alternating voltage to one or more motor windings, e.g. winding Wa, to provide stable operation of the motor at a reduced speed. The result is very efficient operation with minimal switching. 
       FIG.  42    depicts a measurement of motor current and AC input voltage for a motor operating at ⅔ of full synchronous speed using the delayed firing angle with zero current shutoff. For improved operation at lower speeds, one or more additional windings may be added to the multispeed AC machine circuit  3502  to increase the BEMF at lower speeds, reduce the peak current draw, and improve power factor and efficiency. 
       FIG.  43    depicts one example of a multispeed AC machine circuit  3502  with an additional winding Wb and two additional power switches. The example of  FIG.  43    includes a second stator winding Wb connected between point B  3510  and point C  4302 . Point C is the end side of the second winding. The first stator winding Wa is used when the motor is operating at full synchronous speed. The second winding Wb is used when the motor is operating at startup or at a fractional speed, including half speed. 
     The example of  FIG.  43    also includes six of power switches Q 1 , Q 2 , Q 3 , Q 4 , Q 5 , and Q 6  that connect the windings to either L 1  or L 2 . Switch Q 1  connects Point A to L 1 , and switch Q 4  connects Point A to L 2 . Switch Q 2  connects Point B to L 1 , and switch Q 5  connects Point B to L 2 . Switch Q 3  connects Point C to L 1 , and switch Q 6  connects Point C to L 2 . Switches Q 1 , Q 2 , Q 3 , Q 4 , Q 5 , and Q 6  are bi-directional switches allowing current to flow from L 1  to L 2  or from L 2  to L 1 . Switch Q 5  includes a High Speed SSR (QSSR) that includes a MOSFET with diodes  4304 - 4310  configured as a full-wave bridge rectifier. Switch Q 6  also includes a High Speed SSR (QSSR) that includes a MOSFET with diodes  4312 - 4318  configured as a full-wave bridge rectifier. 
     In the example of  FIG.  43   , a current sensor  4320  is placed between Point A  3508  and the of power switch pair Q 1 /Q 4 . Since current is always flowing through the winding Wa, a single current sensor  4320  at this location will provide an accurate current measurement through the windings Wa and Wb. The current measurement is transmitted from the current sensor  4320  to the control circuit  3506 B. This current measurement may be used to either sense current zero crossings or detect over current situations and used by the control circuit  3506 B, for example for start-up and other operation as described herein. 
     In one example of operation, as shown in  FIG.  43   , the control circuit  3506 B activates (closes) the switch pair Q 1 /Q 6  or the switch pair Q 3 /Q 4  to use both windings Wa and Wb in series for startup of the motor for low or fractional speed operation by transmitting signals to the switch pair Q 1 /Q 6  and the switch pair Q 3 /Q 4  either to open/close the switch pair Q 1 /Q 6  and open/close the switch pair Q 3 /Q 4 . Current may still be passed either from L 1  to L 2  or from L 2  to L 1  through both windings Wa and Wb. For full speed operation the control circuit  3506 B activates (closes) the switch pair Q 1 /Q 5  or the switch pair Q 2 /Q 4  to use only winding Wa while not passing any current through winding Wb. The control circuit transmits signals to the switch pair Q 1 /Q 5  and the switch pair Q 2 /Q 4  to open/close the switch pair Q 1 /Q 5  and to open/close the switch pair Q 2 /Q 4 . 
     In another example of operation, as shown in  FIG.  44   , current will only flow from L 1  to L 2  through both sets of windings Wa and Wb for startup or fractional speed operation. If the rotor position signal from the Hall effect device  3606  is high, switches Q 1  and Q 6  are equal to the Hall effect signal from the Hall effect device  3606  and switches Q 3  and Q 4  are equal to the inverse of the Hall effect signal. For example, if L 1  is high and the Hall effect signal is high, current will flow from L 1  through switch Q 1 , through both windings Wa and Wb, and out switch Q 6  to L 2 . If the Hall effect signal is low, switches Q 1  and Q 6  will be open while switches Q 3  and Q 4  will be closed, allowing current that is still flowing from L 1  to L 2  to pass in the opposite direction through the coils. In this example when using both windings Wa and Wb current may only flow from L 1  to L 2 . There will be two switches always on to prevent shutoff spikes. Diodes block the current from flowing in the wrong direction when the AC detection signal is low while still allowing the energy in the coils to get back to the line voltage. Current may still be passed in either direction, from L 1  to L 2  or from L 2  to L 1 , through the coils in either direction in full speed mode using only winding Wa. 
     In one example of operation of a full speed setting and operation by the multispeed AC machine circuit  3502 , the startup mode is only used at speeds lower than 400 RPM and both windings Wa and Wb are used. Once the motor is moving faster than 400 RPMs, the winding Wb is no longer used. Pulse-width modulation is used, as described above, to limit current after that point. The Hall effect signal and the AC polarity signal are XOR&#39; d together by the control circuit  3506 B to create a driving logic signal. Once the motor reaches full speed, the Hall effect signal is shifted as described above. The Hall effect signal is retarded for an over-rev condition and advanced for under-rev condition. The Hall effect signal is shifted for every sensor period that is outside of a 100 micro second window. The Hall effect signal shifts different amounts based on how far outside of the window it is. 
     In this example, for full speed synchronous mode, there is a 1 micro second window that the sensor time period has to be in for 5 seconds before the circuit will try to become synchronous. Once the motor has been stable inside this window for 5 seconds the software determines which 2 power switches have been on the most and it leaves them on. No more switching occurs unless an over current situation is detected or a change in speed is detected. 
     In this example, for half speed, once 600 rpm is achieved, the circuit will continue to switch with the hall but only when the AC detection signal is high. The sensor is then shifted in the software to get the motor to stabilize at 600 rpm. It is retarded for an over-rev condition and advanced if more power is needed. The sensor never advances past its actual location. 
       FIG.  44    depicts an example of a multispeed AC machine circuit  3502  with four bi-directional power switches and two unidirectional power switches. Power switches Q 1 , Q 2 , Q 4  and Q 5  are bi-directional power switches allowing current to flow from L 1  to L 2  or from L 2  to L 1 . Power switches Q 3  and Q 6  are unidirectional power switches. Current can only flow from L 1  into power switch Q 3 , and current can only flow into power switch Q 6  and out to L 2 . 
       FIG.  45    depicts an example of simplified multispeed AC machine circuits  3502 D. The power switches of  FIG.  45    can be other types of switches than those described above, such as a switching device or combination of switching devices that allow for the switching of alternating current, including metal-oxide-semiconductor field-effect transistors (MOSFETs), silicon-controlled rectifiers (SCRs), or transistors configured to operate as AC switches, for example when placed in series in opposite directions with diodes, or relays or any other combination of switches that can be configured for switching alternating current. But, the circuit of  FIG.  45    operates as the  FIGS.  35 ,  36 , and  43    described above. Other configurations of components can be used that effectively connect one or more windings directly or indirectly to the incoming AC voltage. 
       FIG.  46    depicts an example of simplified multispeed AC machine circuits  3502 E. The circuit of  FIG.  46    depicts has an additional winding for fractional speed optimization and simplification of Q 3  and Q 6  for a limited number of fractional speeds. At half synchronous speed power switch pairs Q 1 /Q 6  or Q 3 /Q 4  can be left on to allow current flow back to the line while alternating the energized pair based on rotor position. The power switches of  FIG.  46    can be other types of switches than those described above, such as a switching device or combination of switching devices that allow for the switching of alternating current, including metal-oxide-semiconductor field-effect transistors (MOSFETs), silicon-controlled rectifiers (SCRs), or transistors configured to operate as AC switches, for example when placed in series in opposite directions with diodes, or relays or any other combination of switches that can be configured for switching alternating current. 
       FIG.  47    depicts another example of a simplified multispeed AC machine circuit  3502 F. The power switches of  FIG.  47    can be types of power switches other than those described above, such as a switching device or combination of switching devices that allow for the switching of alternating current, including metal-oxide-semiconductor field-effect transistors (MOSFETs), silicon-controlled rectifiers (SCRs), or transistors configured to operate as AC switches, for example when placed in series in opposite directions with diodes, or relays or any other combination of switches that can be configured for switching alternating current. But, the circuits of  FIG.  47    operate as the  FIGS.  35 ,  36 , and  43    described above. However, the additional winding and two additional power switches Q 7  and Q 8  enable further optimization at different speeds or load requirements. Adding additional windings increases the BEMF, the total resistance of the windings, and the impedance of the windings. For example, different wire guages may be used on the additional windings to increase efficiency when running a large motor at small load, essentially creating a smaller motor inside a bigger motor. 
     In other embodiments, the disclosure herein includes methods for providing the components described herein for a machine, including for a motor or a generator. 
     In one aspect, a multispeed alternating current (AC) machine circuit is for an AC power source having a first side and a second side. The AC machine circuit includes two or more pairs of power switches, one or more windings, and a control circuit to close one pair of power switches to cause current to flow from a first side of the AC power source, through the one or more windings, to the second side of the AC power source and to close the other pair of power switches to cause current to flow from the second side of the AC power source, through the one or more windings, to the first side of the AC power source. 
     In another aspect, a circuit is for a machine having alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The circuit comprises a winding with a start side and an end side, a first power switch connected between the first side and the winding start side, a second power switch connected between the second side and the winding start side, a third power switch connected between the first side and the winding end side, a fourth power switch connected between the second side and the winding end side, and a control circuit. The control circuit closes the first power switch and the fourth power switch and open the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and open the first power switch and the fourth power switch to cause current to flow from the second side to the first side. 
     In another aspect, a circuit is for a machine having alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The circuit comprises a first winding with a first start side and a first end side, a second winding with a second start side and a second end side, a first power switch connected between the AC power source first side and the first winding start side, a second power switch connected between the AC power source second side and the first winding start side, a third power switch connected between the AC power source first side and the first winding end side, a fourth power switch connected between the AC power source second side and the first winding end side, a fifth power switch connected between the AC power source first side and the second winding end side, a sixth power switch connected between the AC power source second side and the second winding end side, and a control circuit. The control circuit closes the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or closes the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. 
     In another aspect, a method is for a multispeed alternating current (AC) machine circuit for an AC power source having a first side and a second side. The method includes providing two or more pairs of power switches, providing one or more windings, and providing a control circuit to close one pair of power switches to cause current to flow from a first side of the AC power source, through the one or more windings, to the second side of the AC power source and to close the other pair of power switches to cause current to flow from the second side of the AC power source, through the one or more windings, to the first side of the AC power source. The method further includes providing components for the control circuit described herein and operating the circuit as described herein. 
     In another aspect, a method is for a circuit for a machine having alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The method comprises providing a winding with a start side and an end side, providing a first power switch connected between the first side and the winding start side, providing a second power switch connected between the second side and the winding start side, providing a third power switch connected between the first side and the winding end side, providing a fourth power switch connected between the second side and the winding end side, and providing a control circuit. The control circuit closes the first power switch and the fourth power switch and open the second power switch and the third power switch to cause current to flow from the first side to the second side or closes the second power switch and the third power switch and open the first power switch and the fourth power switch to cause current to flow from the second side to the first side. The method further includes providing components for the control circuit described herein and operating the circuit as described herein. 
     In another aspect, a method is for a circuit for a machine having alternating current (AC) power source having a first side (L 1 ) and a second side (L 2 ). The method comprises providing a first winding with a first start side and a first end side, providing a second winding with a second start side and a second end side, providing a first power switch connected between the AC power source first side and the first winding start side, providing a second power switch connected between the AC power source second side and the first winding start side, providing a third power switch connected between the AC power source first side and the first winding end side, providing a fourth power switch connected between the AC power source second side and the first winding end side, providing a fifth power switch connected between the AC power source first side and the second winding end side, providing a sixth power switch connected between the AC power source second side and the second winding end side, and providing a control circuit. The control circuit closes the first power switch and the sixth power switch and open the second power switch, the third power switch, the fourth power switch, and the fifth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the third power switch and the fourth power switch and open the first power switch, the second power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding and the second winding for fractional speed operation or closes the first power switch and the fifth power switch and open the second power switch, the third power switch, the fourth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation or closes the second power switch and the fourth power switch and open the first power switch, the third power switch, the fifth power switch, and the sixth power switch to cause current to flow through the first winding for full speed operation. The method further includes providing components for the control circuit described herein and operating the circuit as described herein. 
     Those skilled in the art will appreciate that variations from the specific embodiments disclosed above are contemplated by the invention. The invention should not be restricted to the above embodiments, but should be measured by the following claims.