Abstract:
System, method, and apparatus for commutating and controlling a multi-phase motor using one output rotor sensor and circuitry that measures time between rotor pole-to-pole transitions is disclosed. The exemplary system, method, and apparatus may utilize the polarity of the single-output rotor sensor and the measured time between the polarity transitions detected by the single-output rotor sensor.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     The present application claims priority from U.S. provisional patent application Ser. No. 60/758,421, filed Jan. 12, 2006, by Mark Collins, incorporated by reference herein and for which benefit of the priority date is hereby claimed. 
     
    
     TECHNICAL FIELD  
       [0002]     The present invention relates to multi-phase motors and more particularly, relates to a controller for a multi-phase motor.  
       BACKGROUND INFORMATION  
       [0003]     In many commercial motor applications, for example computer fans, there is a need to reduce size and cost of the motor and motor system. However, while reducing the size and cost of the motor and motor system, an increase in motor torque is often desirable. For example, in the above computer fan application, the size and cost of the overall computers are decreasing, thus creating a need to reduce the size and cost of the applicable fan motors and fan motor systems. In addition, a reduction in size of the computer combined with an increase in computational performance typically means that more heat is internally generated inside the computer. For product reliability purposes, this increased heat may need to be removed from the product. The need to remove more heat may require a fan motor that generates greater torque while, at the same time, reducing the size and cost of the fan motor and fan motor system.  
         [0004]     In one prior art application, a 1-coil or a 2-coil winding motor is used to provide low cost and low complexity. But as more torque may be required (due to increased heat removal requirements), the 1-coil or 2 coil winding motor may have limited efficiency and torque output. Multiphase motors may be more efficient and provide greater torque due to the reduced percentage of the low or no torque angles of rotation.  
         [0005]     A multiphase motor control may utilize three sensors that may need to be accurately placed at precise locations at predefined distances apart from each other. These three sensors (that are located at different locations) detect rotor angular motion at different times (due to their respective different placement locations). This allows the system to distinguish each phase in the motor stator. This multiphase motor control may require precision assembly methods to properly locate three sensors and also the additional equipment cost of the three sensors.  
         [0006]     Another type of multiphase motor control has one sensor but may also require a more complex rotor. This rotor includes physical coding or marking to distinguish between each stator phase. This more complex rotor may involve more material and assembly costs.  
         [0007]     There is also a method for multiphase motor control called ‘sensorless’ control. This method typically involves monitoring the BEMF voltages of the motor stator windings, which are then used to interpolate phase location. This method does not involve the cost of any sensors, but may require complex, precision analog-type circuitry. Therefore, this ‘sensorless’ method may require the cost of the complex circuits and the cost associated with the time required to test and validate these complex circuits.  
         [0008]     Accordingly, a need exists for a device, method, and system that provides less complex circuitry and easier implementation in a variety of applications and, therefore, is typically more cost effective. In addition, the device, method and system may only require the cost of one sensor and may not require the precision assembly and location of multiple sensors. In addition, the device, method and system may not require any physical coding or marking (other than the standard rotor magnetic pole-pairs) to distinguish each stator phase and, therefore, does not require the material and/or cost that the more complex rotor may incur. In addition, the device method and system may reduce the cost of multiphase motors so as to allow them to become more commercially feasible in applications that previously were only commercially feasible as 1-coil or 2-coil motors.  
       SUMMARY  
       [0009]     The present invention provides an improved multiphase motor system. The multiphase motor system may utilize a single-output sensor with a rotor pole-to-pole time counter and controller/driver. The multiphase motor system may also utilize a standard (no extra coding/marking) rotor and stator.  
         [0010]     The controller/driver of the system may use the single-output sensor, the rotor pole-to-pole time counter and the knowledge of the present ‘driven’ (energized) stator phase to determine when and which phase to commutate in the multiphase motor. Depending on system phase conditions, the controller/driver may commutate the motor windings immediately upon sensing a polarity change of the single-output sensor (which monitors angle rotation of the rotor) or may commutate the motor stator windings based on the rotor pole-to-pole time-counter which continuously measures time between polarity changes of the single-output sensor and adaptively adjusts the time to commutate based on the most-recent rotor pole-to-pole polarity changes. Another exemplary embodiment may combine the last several most-recent pole-to-pole times together and then use this as a basis to determine when to properly commutate the motor stator windings. Yet another exemplary embodiment may combine the most-recent pole-to-pole time(s) momentarily with another time count based on the condition that the motor is just starting and is in an acceleration mode in order to increase speed as a basis to determine when to properly commutate stator windings. And yet another exemplary embodiment may combine the most-recent pole-to-pole time(s) momentarily with another time count based on an external signal in order to increase or decrease speed as a basis to determine when to properly commutate stator windings. And yet another exemplary embodiment may combine the most-recent pole-to-pole time(s) momentarily with another time count based on system power supply voltage in order to increase or decrease speed as a basis to determine when to properly commutate stator windings.  
         [0011]     The system can be adapted to many multiphase motor system configurations. For example, the system can be used to control a 3-phase unipolar or bipolar motor, a 4-phase unipolar motor, or many other coil winding configurations. The system can also be adapted to be used to control motor systems in which the rotor pole count does not match the stator pole count. For example, the system can be used to control a 3-phase stator and a 2-pole-pair rotor. Note that it can be used to drive motor systems wherein the stator pole count and the rotor pole-pair count are not equal. The invention may provide one or more of the following advantages. 
    (1) requires only 1 single-output rotor angular location sensor     (2) requires only physical placement of 1 single-output rotor angular location sensor     (3) requires only a standard permanent-magnet rotor (meaning rotor comprised of only the magnetic pole-pairs that purposely interact with the stator)     (4) any or all of electronic parts of the system may be integrated into one IC (meaning the sensor, rotor pole-to-pole time counter, controller, acceleration/deceleration compensator, commutation time counter, pre-driver and driver)     (5) system can be of general use due to adaptability to many different motors (meaning motors of different sizes, powers, and coil impedances, as well as, motors of different pole counts and styles)     (6) cost can be low due to low component count and use of ‘standard’ components     (7) size can be small due to low component count and high amount of possible integration     (8) adaptable to varying system speed and load conditions due to continuous measurement and updating of the rotor pole-to-pole time counter    
 
         [0020]     It is important to note that the present invention is not intended to be limited to a device, system, or method which must satisfy one or more of any stated objects, advantages, or features of the invention. It is also important to note that the present invention is not limited to the exemplary embodiments described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]     These and other features and advantages of the present invention will be better understood by reading the following detailed description, taken together with the drawings wherein:  
         [0022]      FIG. 1  is a diagram of the multiphase motor system according to an exemplary embodiment of the present invention.  
         [0023]      FIG. 2A  is the stator  100 , rotor  200 , rotor sensors  300  and controller  400  of a first prior art system.  
         [0024]      FIG. 2B  is the stator  100 , rotor  250 , rotor sensor  350  and controller  400  of a second prior art system.  
         [0025]      FIG. 2C . is the stator  100 , rotor  275 , rotor sensor  300  and controller  400  of a third prior art system.  
         [0026]      FIG. 3  is the stator  100 , rotor  200 , rotor sensor  300 , controller  400  and the rotor pole-to-pole time counter  500  according to an exemplary embodiment of the present invention.  
         [0027]      FIG. 4  is a graph showing relative torque of different phases versus angle of rotation of a 3-phase unipolar motor.  
         [0028]      FIG. 5  is an exemplary version of controller/driver phase states versus angle of rotation when the single-output rotor sensor  30  is rotationally centered between stator poles in a 3-phase unipolar motor system.  
         [0029]      FIG. 6  is an exemplary version of controller/driver phase states versus angle of rotation when the single-output rotor sensor  30  is rotationally centered on a Stator pole in a 3-phase unipolar motor system.  
         [0030]      FIG. 7  is an exemplary version of controller/driver phase states versus angle of rotation when the single-output rotor sensor  30  is rotationally placed at an arbitrary angle between Stator poles in a 3-phase unipolar motor system.  
         [0031]      FIG. 8  is a graph showing relative torque of different phases versus angle of rotation of a 4-phase unipolar motor.  
         [0032]      FIG. 9  is an exemplary version of controller/driver phase states versus angle of rotation when the single-output rotor sensor  30  is rotationally centered between stator poles in a 4-Phase unipolar motor system.  
         [0033]      FIG. 10  is an exemplary version of controller/driver phase states versus angle of rotation when the single-output rotor sensor  30  is rotationally centered on a stator pole in a 4-phase unipolar motor system.  
         [0034]      FIG. 11  is an exemplary version of controller/driver phase states versus angle of rotation when the single-output rotor sensor  30  is rotationally placed at an arbitrary angle between stator poles in a 4-phase unipolar motor system.  
         [0035]      FIG. 12  is a graph showing relative torque of different phases versus angle of rotation of a 3-phase bipolar motor.  
         [0036]      FIG. 13  is an exemplary version of controller/driver phase states versus angle of rotation when the single-output rotor sensor  30  is rotationally centered between stator poles in a 3-phase bipolar motor system.  
         [0037]      FIG. 14  is an exemplary version of controller/driver phase states versus angle of rotation when the single-output rotor sensor  30  is rotationally centered on a stator pole in a 3-phase bipolar motor system.  
         [0038]      FIG. 15  is an exemplary version of controller/driver phase states versus angle of rotation when the single-output rotor sensor  30  is rotationally placed at an arbitrary angle between stator poles in a 3-phase bipolar motor system.  
         [0039]      FIG. 16  is a diagram of the multiphase motor system shown internal components according to an exemplary embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0040]     Referencing  FIG. 1 , a multiphase DC permanent-magnet motor system schematic incorporating a single one-output rotor position sensor  600  and a rotor pole-to-pole time counter  500  is depicted according to an exemplary embodiment of the invention. Also shown are the motor controller logic/pre-drivers  700 , the multiphase drivers  800  and the motor rotor/stator  900  as well as two optional devices (acceleration/deceleration compensator  750  and commutation time counter  775 ).  
         [0041]     In a multiphase ‘sensored’ permanent-magnet motor system, the rotor position sensor  600  is utilized to detect discrete angular steps of rotational travel of the rotor  900  in real time. The angular value of the discrete angular steps of rotational travel may be defined by the number of magnetic poles in the standard permanent-magnet rotor. For example, in a typical rotor of 2 pole-pairs (4 poles), each discrete step is 90 rotational degrees ((360°/4 poles)=90°). The exemplary embodiment of the present invention may utilize the detected angular travel of one single-output sensor monitoring a standard rotor to determine when to properly commutate the multiple phases of the multiphase stator. This may be achieved by utilizing the rotor pole-to-pole time counter  500  to measure time between the polarity changes of the sensor  600  (in real time) and then utilizing the controller logic  700  to determine when (in real time) to commutate the multiple winding phases of the motor  900 , via the motor drivers  800 . The commutation of the motor may be based on the two sets of available data—the instantaneous polarity data (which infers present angular location) of the sensor  600  and the most-recent pole-to-pole time data (which infers approximate present angular velocity).  
         [0042]     An optional exemplary variation of the system may include an acceleration/deceleration compensator  750 , which modifies the output value of the rotor pole-to-pole time counter  500  under, for example, one or both of the following conditions (a) during motor speed ramp-up (acceleration) period at power-up or (b) during a system voltage supply change which results in a motor speed change (acceleration or deceleration). During the period at system power-up when the rotor velocity is accelerating (motor speed ramp-up time), the time between each rotor pole-to-pole period is decreasing so an accelerator/deceleration compensator  750  can be used to modify the times at which the controller  700  commutates the stator phases. After normal operating velocity is achieved, the acceleration/deceleration compensator  750  may no longer be utilized. The accelerator/deceleration compensator modifies/improves commutation times by decreasing the value of the rotor pole-to-pole time counter. Or during the period immediately following a system voltage supply change, the rotor velocity is accelerating or decelerating depending on whether the system voltage supply increased or decreased. During this period, the time between each rotor pole-to-pole period is changing (it is decreasing for rotor velocity increase or increasing for rotor velocity decrease) so an accelerator/deceleration compensator  750  can be used to modify the times at which the controller  700  commutates the stator phases. After normal operating velocity is achieved, the acceleration/deceleration compensator  750  may no longer be utilized. The accelerator/deceleration compensator improves commutation times by modifying the value of the rotor pole-to-pole time counter. Either an external signal or internal sensing signal (which sense a change in the system voltage supply) can operate the acceleration/deceleration  750  compensator.  
         [0043]     Another optional exemplary variation of this system may include a commutation time counter  775 . In many applications, depending on the number of rotor pole-pairs versus stator phases or depending on the arbitrary physical placement of the rotor sensor  600  in reference to the physical stator poles, it may be desirable to use a value of time count that is different from but yet still based on, the actual rotor pole-to-pole time count output. For example a time count value of ⅓ (or ⅔ or 4/3 etc.) of the actual measured rotor pole-to-pole time may be desired. So the commutation time counter  775  may modify the output of the rotor pole-to-pole time counter  500  so as to generate the desired time count value. The output of the commutation time counter  775  may then be utilized by the controller  700  to properly commutate the stator phases.  
         [0044]     Referencing  FIG. 2A , a prior art 3-phase stator  100  and 2-pole-pair rotor  200  is combined with a quantity of three one-output rotor position sensors  300  and a controller  400 . Each one of the three sensors  300  may need to be located with angular precision in relation to the other sensors  300 . The quantity of three sensors and additional precision assembly location of the three sensors adds extra costs. Since there are three stator  100  poles and only two rotor  200  pole-pairs, the combination of the three sensors  300  outputs are required to determine angular position and, hence, when to commutate properly. The present angular position is determined based on the known angular relationship between the three sensors  300  and the standard magnetic regions of the rotor  200  which are detected by the three one-output sensors  300  and combined with the controller&#39;s  400  knowledge of last phase.  
         [0045]     Referring to  FIG. 2B , another version of prior art multiphase motor system has a 3-phase stator  100  combined with a non-typical 2-pole-pair rotor  250 . The multiphase motor system may also have a two-output rotor position sensor  350  and a controller  400 . Since there are 3 stator  100  poles and only 2 standard rotor pole-pairs, the non-typical rotor  250  includes additional magnetic and non-magnetic regions which combined with the two-output sensor  350  is required to determine angular position and, hence, when to commutate properly. The non-typical rotor  250  is manufactured by including extra magnetic pole regions and non-magnetic regions in specific regions of the rotor in addition to the standard magnetic poles. This may require extra manufacturing costs. In addition, two-output sensor may be required to differentiate between 3 different magnetic field intensity values. The present angular position may be determined based on the additional magnetic regions imbedded into the rotor  250  which are detected by the two-output sensor  350  and combined with the controller&#39;s  400  knowledge of last phase.  
         [0046]     Referring to  FIG. 2C , a prior art system may combine a 3-phase stator  100  with a non-typical 2-pole-pair rotor  275 . The prior art system also has one-output rotor position sensor  300  and a controller  400 . Since there are 3 stator  100  poles and only 2 standard rotor pole-pairs, the non-typical rotor  275  includes additional magnetic regions which combined with the one-output sensor  300  may be required to determine angular position and, hence, when to commutate properly. The non-typical rotor  275  may be manufactured by including extra magnetic pole regions in specific regions of the rotor in addition to the standard magnetic poles. The present angular position may be determined based on the additional magnetic regions imbedded into the rotor  275  which may be detected by the one-output sensor  300  and combined with the controller&#39;s  400  knowledge of last phase.  
         [0047]     Referring to  FIG. 3 , according to an exemplary embodiment of the invention a 3-phase stator  100  may be combined with a 2-pole-pair rotor  200 . The exemplary system may have one-output rotor position sensor  300 , a controller  400 , and a rotor pole-to-pole time counter  500 . The rotor  200  combined with the one-output sensor  300  and with the electronic rotor pole-to-pole time counter  500  may be used to determine angular position and, hence, when to commutate properly. Since there are 3 stator  100  poles and only 2 rotor  200  pole-pairs, the combination of sensor  300  output and the rotor pole-to-pole time counter  500  may be used to determine angular position and, hence, when to commutate properly. The present angular position may be determined based on the standard magnetic regions of the rotor  200  which are detected by the one-output sensor  300  and the output of the rotor pole-to-pole time counter  500  and combined with the controller&#39;s  400  knowledge of last phase.  
         [0048]     Now referencing  FIG. 16 , a more detailed explanation is disclosed. As the rotor  200  rotates about the stator  100  (due to the changing magnetic fields generated by changing stator phase energizations), the magnetic poles of the rotor rotate by the rotor sensor  600 . The sensor  600  detects the polarities of the rotor magnetic poles as they rotate by the sensor  600 . The sensor  600  thus outputs (to both the rotor pole-to-pole time counter  500  and the controller  700 ) an electronic logical high level or low level, which represents the magnetic polarity of the rotor pole which is rotating by at that point in time. Each time that the sensor output level changes state, the rotor pole-to-pole time counter may perform three actions: 1) stops the present pole-to-pole time count, 2) starts a new pole-to-pole time count and 3) outputs the just completed pole-to-pole time count to the controller  700 . At this point in time, depending on the present system status (of which the controller  700  is knowledgeable of), the controller  700  may either immediately commutate to the next stator  100  phase (via the drivers  800 ) or may wait an amount of time equal to or based on the rotor pole-to-pole time count that the controller  700  has just received (called the most-recent pole-to-pole time count) from the rotor pole-to-pole time counter  500  and after this time based on the most recent pole-to-pole time count has elapsed then the controller  700  commutates to the next stator  100  phase (via the drivers  800 ). When the stator  100  phase is commutated, the stator magnetic field changes which causes the rotor  200  to continue to rotate. The entire system process continues to repeat. Thus, a multiphase motor can be operated by a single one-output rotor sensor combined with a rotor pole-to-pole time counter.  
         [0049]     Still referencing  FIG. 16 , at motor start-up (time zero), the controller  700  may not know precisely what angular location the rotor  200  may be at because the rotor may have previously been located in many angular locations and the single rotor sensor  600  may not supply enough location data to precisely determine location. The controller  700  may force the rotor  200  to move and stop at a pre-defined location by energizing a pre-defined stator  100  phase. At this point, the controller  700  now has knowledge of the present status of the motor system (the present stator  100  phase is known as well as the output level of the rotor sensor  600  which is sensing the adjacent rotor  200  magnetic pole). Now to start desired rotor  200  motion, the controller  700  commutates the stator  100  to the next stator phase (the next sequential phase after the pre-defined phase) and commands the rotor pole-to-pole time counter  500  to start the first pole-to-pole time count. Now commutating the stator phase causes the rotor  200  to rotate in the desired direction. Next, when the rotor sensor  600  detects a change in rotor magnetic polarity (due to rotor rotation), the rotor pole-to-pole time counter  500  completes the first (now the most-recent pole-to-pole time count). At this point, the controller  700  may utilize the most-recent pole-to-pole time count and the system configuration to determine when to commutate the stator  100  to the next phase. The controller  700  may commutate to the next phase immediately upon receiving notice of the first rotor sensor  600  output level change. Now the controller  700  may have all the data to continue motor operation: 1) the present phase that the stator is in, 2) the output level of the rotor sensor and 3) the most-recent pole-to-pole time count. Thus the controller  700  keeps the motor operating by continuously monitoring the data inputs and utilizing them to commutate the stator phases at the proper times based on the pre-defined system configuration. Depending on both the system configuration and the present system status, the controller  700  determines the proper commutation times in sequence.  
         [0050]     Another performance embodiment of the systems involves what happens when the motor becomes stalled (rotor is locked in one position). In the case where the controller  700  has determined to commutate time-coincident with the next occurrence of the rotor sensor  600  detecting a new rotor  200  magnetic pole, the controller  700  correctly knows what state the rotor and stator were in at the point in time that the stall occurred because the rotor magnetic pole change has not occurred. Thus the controller  700  can attempt to properly re-start the motor based on current status. In the case where the controller  700  may have determined to commutate due to a time count based on the most-recent pole-to-pole time count having fully elapsed. The controller  700  may incorrectly assume what angular location the rotor  200  should have reached but has not yet reached. However, this possible incorrect assumption may not be a problem, because the controller  700  can attempt to properly re-start the motor based on the incorrect data. The phase that the controller  700  may energize may be in the correct direction and may be adequate in magnitude of torque (assuming that all locking mechanism has been removed). If the correct phase had been energized, more torque would have been generated, but the phase that the controller  700  did energize may be adequate. There is also another option that may be utilized after a stall. In place of trying to re-start the motor at the stator  100  phase where the controller  700  assumes that the stall occurred (as described in above paragraph), a normal pre-defined start-up with the pre-defined alignment phase can be implemented as previously described.  
         [0051]     Still referencing  FIG. 16 , the acceleration/deceleration compensator  750  can be used to modify the output value of the most-recent pole-to-pole time count. The purpose of this value modification is to more properly predict the time to commutate to the next stator phase  100  when the motor rotational velocity is increasing or decreasing. The acceleration/deceleration compensator  750  may subtract an amount of time value from the most-recent pole-to-pole time value and, thereby, force the next stator  100  phase commutation to occur earlier than the most-recent pole-to-pole time value would have done. This option may be utilized when a decrease in pole-to-pole time is anticipated, for example, in motor speed ramp-up time at power-up or when the system voltage supply has increased. The acceleration/deceleration compensator  750  may add an amount of time value from the most-recent pole-to-pole time value and, thereby, force the next stator  100  phase commutation to occur later than the most-recent pole-to-pole time value would have done. This option may be utilized when an increase in pole-to-pole time is anticipated, for example, when the system voltage supply has decreased. The acceleration/deceleration compensator  750  may be activated by one or all of the following conditions: (a) the power-up process occurring or (b) by an external signal or (c) an internal sensor detecting a change of the system voltage supply. After the motor velocity is constant, the acceleration compensator  750  may not be utilized.  
         [0052]     Still referencing  FIG. 16 , the commutation time counter  775  can be used to modify the output value of the most-recent pole-to-pole time count. The purpose of this value modification is to more properly predict the time to commutate to the next stator phase  100  when the desired proper time count value is not exactly equal to the measured rotor pole-to-pole time count value but is mathematically related to the measured rotor pole-to-pole time count value. Depending on system configurations, some common desired time count value relationships are ½, ⅓, ⅔, 4/3. However, any desired time count value relationships may be utilized. The output of the commutation time counter  775  may then be utilized by the controller  700  to properly commutate the stator phases.  
         [0053]     As previously noted, the rotor pole-to-pole time counter  500  may be used to measure the time that passes while the rotor  200  is rotating through one entire magnetic pole. The rotor pole-to-pole time counter may be an electronic clock pulse counter. As such, the counter would count the number of system clock pulses that occur during the time that it takes for the rotor  200  to rotate one magnetic pole completely by the rotor sensor  600 . The system clock may be the same clock utilized by the controller  700 . The system clock may be internal to the controller  700  or may be an external clock imported into the motor system. The rotor pole-to-pole time counter may also use a clock which is a fractional frequency of the system clock; such as ½ or ⅓ or ¼ or any fractional value of the system clock. The use of a fractional frequency (of the system clock) clock in the rotor pole-to-pole time counter while using the true system clock in the controller  700  effectively generates rotor pole-to-pole time count values that are fractional to the true rotor pole-to-pole time count value and as such the output of the rotor pole-to-pole time counter  500  may be directly useable (without any modification) by the controller  700  to generate commutation of the stator  100  phases at the proper time (in real time).  
         [0054]     Now referencing  FIG. 4 , the phase-torque versus rotor angle relationship of a 3-phase unipolar motor can be seen. This is based on the arbitrary reference selection as Phase C set at rotational angle of 0°. Note that there may be some overlap of torque among the 3 phases. This overlap of torque is the reason that a 3-phase unipolar motor may be more torque efficient than a 2-phase motor, as noted earlier. If Phase C is set as the pre-defined alignment phase and energized so as to generate a south pole, the rotor may move to and stop at rotational angle of 0°. Thus, at this point, the motor system may have the motor with phase-torque relationship as shown in  FIG. 4 . As can be seen from this phase-torque relationship (after being aligned), the torque generated by de-energizing Phase C and then energizing Phase A may cause the rotor to move/rotate. At 45°, if the system de-energizes Phase A and energizes Phase B, the rotor would continue to rotate and thus continue to follow this de-energization/energization process (commutation) indefinitely. In other words, the motor will continue to rotate.  
         [0055]     Referencing  FIG. 5 , the utilization of an exemplary embodiment will be described via the start-up and rotational process of a 3-phase unipolar stator  10  with a 2-pole-pair permanent-magnet rotor  20  and a single rotor sensor  30  is physically located within the useable magnetic field intensity of the rotor at a rotation angle of the rotor that is centered between the physical structures of two stator poles. In Step  1 , Phase C of the stator  10  is energized as an alignment phase and the rotor  20  moves to and stops at 0°, then Phase C is de-energized. In Step  2 , Phase A is energized and the rotor pole-to-pole counter is started. When the sensor  30  detects a rotor  20  magnetic polarity change, Phase A is de-energized, Phase B is energized. The rotor pole-to-pole counter is stopped and the value outputted to the controller. The rotor pole-to-pole counter is then re-started. In Step  3 , Phase B is energized until the controller counted to a time equal to 4/3 of the most-recent pole-to-pole count. Then Phase B is de-energized and Phase C is energized. In Step  4 , Phase C is energized and when the sensor  30  detects a rotor  20  magnetic polarity change, the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  5 , Phase C is energized until the controller counted to a time equal to ⅓ of the most-recent pole-to-pole count. Then Phase C is de-energized and Phase A is energized. In Step  6 , Phase A is energized and when the sensor  30 , detects a rotor  20  magnetic polarity change, Phase A is de-energized, Phase B is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller. The rotor pole-to-pole counter is then re-started. Steps  3  through  6  are now continuously repeated with the one exception that ⅔ value count may now be used in step  3  ( 4/3 may be used only in the first Step  3 ).  
         [0056]     Referencing  FIG. 6 , an exemplary embodiment will be described via the start-up and rotational process of a 3-phase unipolar stator  10  with a 2-pole-pair permanent-magnet rotor  20  and a single rotor sensor  30  is physically located within the useable magnetic field intensity of the rotor at a rotation angle of the rotor that is centered directly in-line with the physical structure of one stator pole. In Step  1 , Phase C of the stator  10  is energized as an alignment phase and the rotor  20  moves to and stops at 0°, then Phase C is de-energized. In Step  2 , Phase A is energized and the rotor pole-to-pole counter is started. When the sensor  30 , detects a rotor  20  magnetic polarity change the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  3 , Phase A is energized until the controller counted to a time equal to 2 of the most-recent pole-to-pole count. Then Phase A is de-energized and Phase B is energized. In Step  4 , Phase B is energized and when the sensor  30  detects a rotor  20  magnetic polarity change, Phase B is de-energized, Phase C is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  5 , Phase C is energized until the controller counted to a time equal to ⅔ of the most-recent pole-to-pole count. Then Phase C is de-energized and Phase A is energized. In Step  6 , Phase A is energized and when the sensor  30 , detects a rotor  20  magnetic polarity change, the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. Steps  3  through  6  are now continuously repeated with the one exception that ⅓ value count may now be used in Step  3  (2 may be used only in the first Step  3 ).  
         [0057]     Referencing  FIG. 7 , an exemplary embodiment will be described via the start-up and rotational process of a 3-phase unipolar stator  10  with a 2-pole-pair permanent-magnet rotor  20  and a single rotor sensor  30  is physically located within the useable magnetic field intensity of the rotor at a rotation angle of the rotor that is arbitrarily chosen between the physical structures of two stator poles. In Step  1 , Phase C of the stator  10  is energized as an alignment phase and the rotor  20  moves to and stops at 0°, then Phase C is de-energized. In Step  2 , Phase A is energized and the rotor pole-to-pole counter is started. When the sensor  30 , detects a rotor  20  magnetic polarity change the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  3 , Phase A is energized until the controller counted to a time equal to w of the most-recent pole-to-pole count. Then Phase A is de-energized and Phase B is energized. In Step  4 , Phase B is energized until the controller counted to a time equal to x of the most-recent pole-to-pole count. Then Phase B is de-energized and Phase C is energized. In Step  5 , Phase C is energized and when the sensor  30 , detects a rotor  20  magnetic polarity change the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  6 , Phase C is energized until the controller counted to a time equal to y of the most-recent pole-to-pole count. Then Phase C is de-energized and Phase A is energized. Steps  2  through  6  are now continuously repeated with the one exception that z value count may now be used in Step  3  (w may be used only in the first Step  3 ). In this exemplary embodiment, the variables w, x, y and z are a function of the physical placement of the rotor sensor relative to the physical location of the stator poles and have a fractional relationship to the rotor pole-to-pole time count value.  
         [0058]     Now referencing  FIG. 8 , the phase-torque versus rotor angle relationship of a 4-phase unipolar motor can be seen. This is based on the arbitrary reference selection as Phase D set at rotational angle of 0°. Note that there is some overlap of torque among the 4 phases. This overlap of torque may be the reason that a 4-phase unipolar motor is more torque efficient than a 2-phase motor, as noted earlier. If Phase D is set as the pre-defined alignment phase and energized so as to generate a South Pole, the rotor will move to and stop at rotational angle of 0°. Thus, at this point, the motor system will have motor with phase-torque relationship as shown in  FIG. 8 . As can be seen from this phase-torque relationship (after being aligned), the torque generated by de-energizing Phase D and then energizing Phase A may cause the rotor to move (rotate). At 22.5°, if Phase A is de-energized and Phase B energized, the rotor may continue to rotate.  
         [0059]     Referencing  FIG. 9 , an exemplary embodiment will be described via the start-up and rotational process of a 4-phase unipolar stator  10  with a 2-pole-pair permanent-magnet rotor  20  and a single rotor sensor  30  may be physically located within the useable magnetic field intensity of the rotor at a rotation angle of the rotor that is centered between the physical structures of two stator poles. In Step  1 , Phase D of the stator  10  is energized as an alignment phase and the rotor  20  moves to and stops at 0°, then Phase D is de-energized. In Step  2 , Phase A is energized and the rotor pole-to-pole counter is started. When the sensor  30 , detects a rotor  20  magnetic polarity change, Phase A is de-energized, Phase B is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  3 , Phase B is energized until the controller counts to a time equal to 2 of the most-recent pole-to-pole count. Then Phase B is de-energized and Phase C is energized. In Step  4 , Phase C is energized and when the sensor  30  detects a rotor  20  magnetic polarity change, Phase C is de-energized, Phase D is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  5 , Phase D is energized until the controller counted to a time equal to ½ of the most-recent pole-to-pole count. Then Phase D is de-energized and Phase A is energized. In Step  6 , Phase A is energized and when the sensor  30 , detects a rotor  20  magnetic polarity change, Phase A is de-energized, Phase B is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. Steps  3  through  6  may now be continuously repeated with the one exception that ½ value count may now be used in Step  3  (2 may be used only in the first Step  3 ).  
         [0060]     Referencing  FIG. 10 , an exemplary embodiment will be described via the start-up and rotational process of a 4-phase unipolar stator  10  with a 2-pole-pair permanent-magnet rotor  20  and a single rotor sensor  30  is physically located within the useable magnetic field intensity of the rotor at a rotation angle of the rotor that is centered directly in-line with the physical structure of one stator pole. In Step  1 , Phase D of the stator  10  is energized as an alignment phase and the rotor  20  moves to and stops at 0°, then Phase D is de-energized. In Step  2 , Phase A is energized and the rotor pole-to-pole counter is started. When the sensor  30 , detects a rotor  20  magnetic polarity change, Phase A is de-energized, Phase B is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  3 , Phase B is energized until the controller counted to a time equal to ½ of the most-recent pole-to-pole count. Then Phase B is de-energized and Phase C is energized. In Step  4 , Phase C is energized until the controller counted to a time equal to 1 of the most-recent pole-to-pole count. Then Phase C is de-energized and Phase D is energized. In Step  5 , Phase D is energized and when the sensor  30 , detects a rotor  20  magnetic polarity change, the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  6 , Phase D is energized until the controller counted to a time equal to ¼ of the most-recent pole-to-pole count. Then Phase D is de-energized and Phase A is energized. In Step  7 , Phase A is energized until the controller counted to a time equal to ½ of the most-recent pole-to-pole count. Then Phase A is de-energized and Phase B is energized. In Step  8 , Phase B is energized and when the sensor  30 , detects a rotor  20  magnetic polarity change, the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. Then Steps  3  through  8  are continuously repeated with the two exceptions that ¼ value count may now be used in Step  3  (½ may be used only in the first Step  3 ) and that ½ value count may now be used in Step  4  (1 may be used only in the first Step  4 ).  
         [0061]     Referencing  FIG. 11 , an exemplary embodiment will be described via the start-up and rotational process of a 4-phase unipolar stator  10  with a 2-pole-pair permanent-magnet rotor  20  and a single rotor sensor  30  is physically located within the useable magnetic field intensity of the rotor at a rotation angle of the rotor that is arbitrarily chosen between the physical structures of two stator poles. In Step  1 , Phase D of the stator  10  is energized as an alignment phase and the rotor  20  moves to and stops at 0°, then Phase D is de-energized. In Step  2 , Phase A is energized and the rotor pole-to-pole counter is started. When the sensor  30 , detects a rotor  20  magnetic polarity change, Phase A is de-energized, Phase B is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  3 , Phase B is energized until the controller counted to a time equal to w of the most-recent pole-to-pole count. Then Phase B is de-energized and Phase C is energized. In Step  4 , Phase C is energized until the controller counted to a time equal to x of the most-recent pole-to-pole count. Then Phase C is de-energized and Phase D is energized. In Step  5 , Phase D is energized and when the sensor  30 , detects a rotor  20  magnetic polarity change, the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  6 , Phase D is energized until the controller counted to a time equal to y of the most-recent pole-to-pole count. Then Phase D is de-energized and Phase A is energized. In Step  7 , Phase A is energized until the controller counted to a time equal to z of the most-recent pole-to-pole count. Then Phase A is de-energized and Phase B is energized. In Step  8 , Phase B is energized and when the sensor  30 , detects a rotor  20  magnetic polarity change, the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. Steps  3  through  8  may now be continuously repeated with the two exceptions that y value count may now be used in Step  3  (w may be used only in the first Step  3 ) and that z value count may be now used in Step  4  (x may be used only in the first Step  4 ). In this exemplary embodiment, the variables w, x, y and z are a function of the physical placement of the rotor sensor relative to the physical location of the stator poles and have a fractional relationship to the rotor pole-to-pole time count value.  
         [0062]     Now referencing  FIG. 12 , the phase-torque versus rotor angle relationship of a 3-phase bipolar motor can be seen. This is based on the arbitrary reference selection as Phase CA set at rotational angle of 0°. This overlap of torque may be one reason that a 3-phase bipolar motor is more torque efficient than a 2-phase motor, as noted earlier. If Phase CA is set as the pre-defined alignment phase and energized so as to generate a South Pole, the rotor may move to and stop at rotational angle of 0°. Thus, at this point, the motor system may have motor with phase-torque relationship as shown in  FIG. 12 . As can be seen from this phase-torque relationship (after being aligned), the torque generated by de-energizing Phase CA and then energizing Phase AB may cause the rotor to move (rotate). And then, at 30°, if Phase AB is de-energized and Phase AC is energized, the rotor may continue to rotate. Note that one phase (Phase CB) was skipped between alignment with Phase CA and first rotation with Phase AB. This is because torque of Phase CB is already starting to decrease at angle location of 0° and so starting may be better with Phase AB. However, once rotating Phase CB is never skipped again and thus can continue to follow this de-energization/energization process.  
         [0063]     Referencing  FIG. 13 , an exemplary embodiment will be described via the start-up and rotational process of a 3-phase bipolar stator  10  with a 2-pole-pair permanent-magnet rotor  20  and a single rotor sensor  30  is physically located within the useable magnetic field intensity of the rotor at a rotation angle of the rotor that is centered between the physical structures of two stator poles. In Step  1 , Phase CA of the stator  10  is energized as an alignment phase and the rotor  20  moves to and stops at 0°, then Phase CA is de-energized. In Step  2 , Phase AB is energized and the rotor pole-to-pole counter is started. When the sensor  30 , detects a rotor  20  magnetic polarity change, Phase AB is de-energized, Phase AC is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  3 , Phase AC is energized until the controller counted to a time equal to 1 of the most-recent pole-to-pole count. Then Phase AC is de-energized and Phase BC is energized. In Step  4 , Phase BC is energized until the controller counted to a time equal to 1 of the most-recent pole-to-pole count. Then Phase BC is de-energized and Phase BA is energized. In Step  5 , Phase BA is energized and when the sensor  30  detects a rotor  20  magnetic polarity change, Phase BA is de-energized, Phase CA is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  6 , Phase CA is energized until the controller counted to a time equal to ⅓ of the most-recent pole-to-pole count. Then Phase CA is de-energized and Phase CB is energized. In Step  7 , Phase CB is energized until the controller counted to a time equal to ⅓ of the most-recent pole-to-pole count. Then Phase CB is de-energized and Phase AB is energized. In Step  8 , Phase AB is energized and when the sensor  30  detects a rotor  20  magnetic polarity change, Phase AB is de-energized, Phase AC is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. Steps  3  through  8  are now continuously repeated with the two exceptions that ⅓ value count may now be used in Step  3  (1 may be used only in the first Step  3 ) and that ⅓ value count may now be used in Step  4  (1 may be used only in the first Step  4 ).  
         [0064]     Referencing  FIG. 14 , an exemplary embodiment will be described via the start-up and rotational process of a 3-phase bipolar stator  10  with a 2-pole-pair permanent-magnet rotor  20  and a single rotor sensor  30  is physically located within the useable magnetic field intensity of the rotor at a rotation angle of the rotor that is centered directly in-line with the physical structure of one stator pole. In Step  1 , Phase CA of the stator  10  is energized as an alignment phase and the rotor  20  moves to and stops at 0°, then Phase CA is de-energized. In Step  2 , Phase AB is energized and the rotor pole-to-pole counter is started. When the sensor  30 , detects a rotor  20  magnetic polarity change, Phase AB is de-energized, Phase AC is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  3 , Phase AC is energized until the controller counted to a time equal to 1 of the most-recent pole-to-pole count. Then Phase AC is de-energized and Phase BC is energized. In Step  4 , Phase BC is energized until the controller counted to a time equal to 1 of the most-recent pole-to-pole count. Then Phase BC is de-energized and Phase BA is energized. In Step  5 , Phase BA is energized and when the sensor  30  detects a rotor  20  magnetic polarity change, Phase BA is de-energized, Phase CA is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  6 , Phase CA is energized until the controller counted to a time equal to ⅓ of the most-recent pole-to-pole count. Then Phase CA is de-energized and Phase CB is energized. In Step  7 , Phase CB is energized until the controller counted to a time equal to ⅓ of the most-recent pole-to-pole count. Then Phase CB is de-energized and Phase AB is energized. In Step  8 , Phase AB is energized and when the sensor  30  detects a rotor  20  magnetic polarity change, Phase AB is de-energized, Phase AC is energized and the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. Steps  3  through  8  are now continuously repeated with the two exceptions that ⅓ value count may now be used in Step  3  (1 may be used only in the first Step  3 ) and that ⅓ value count may now be used in Step  4  (1 may be used only in the first Step  4 ).  
         [0065]     Referencing  FIG. 15 , an exemplary embodiment will be described via the start-up and rotational process of a 3-phase bipolar stator  10  with a 2-pole-pair permanent-magnet rotor  20  and a single rotor sensor  30  is physically located within the useable magnetic field intensity of the rotor at a rotation angle of the rotor that is arbitrarily chosen between the physical structures of two stator poles. In Step  1 , Phase CA of the stator  10  is energized as an alignment phase and the rotor  20  moves to and stops at 0°, then Phase CA is de-energized. In Step  2 , Phase AB is energized and the rotor pole-to-pole counter is started. When the sensor  30 , detects a rotor  20  magnetic polarity change the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  3 , Phase AB is energized until the controller counted to a time equal to w of the most-recent pole-to-pole count. Then Phase AB is de-energized and Phase AC is energized. In Step  4 , Phase AC is energized until the controller counted to a time equal to x of the most-recent pole-to-pole count. Then Phase AC is de-energized and Phase BC is energized. In Step  5 , Phase BC is energized until the controller counted to a time equal to x of the most-recent pole-to-pole count. Then Phase BC is de-energized and Phase BA is energized. In Step  6 , Phase BA is energized and when the sensor  30  detects a rotor  20  magnetic polarity change, the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. In Step  7 , Phase BA is energized until the controller counted to a time equal to y of the most-recent pole-to-pole count. Then Phase BA is de-energized and Phase CA is energized. In Step  8 , Phase CA is energized until the controller counted to a time equal to z of the most-recent pole-to-pole count. Then Phase CA is de-energized and Phase CB is energized. In Step  9 , Phase CB is energized until the controller counted to a time equal to z of the most-recent pole-to-pole count. Then Phase CB is de-energized and Phase AB is energized. In Step  10 , Phase AB is energized and when the sensor  30  detects a rotor  20  magnetic polarity change the rotor pole-to-pole counter is stopped and the value outputted to the controller and then the rotor pole-to-pole counter is re-started. Steps  3  through  10  are now continuously repeated with the two exceptions that y value count may now be used in Step  3  (w may be used only in the first Step  3 ) and that z value count may now be used in Step  4  (x may be used only in the first Step  4 ). In this exemplary embodiment, the variables w, x, y and z are a function of the physical placement of the rotor sensor relative to the physical location of the stator poles and have a fractional relationship to the rotor pole-to-pole time count value.  
         [0066]     Now it is important to re-iterate the adaptability of this system to many motors and motor system applications. As shown above via the many examples above (which does not mean to limit, but only to demonstrate the adaptability) of motor type and sensor placements, the system is very adaptable. Other Step processes (which have not been shown as examples) may be utilized in conjunction with this new invention. Note also that the selection to align to Phase C or Phase D or Phase CA is arbitrary also. The new invention is adaptable to many other selections. The system is also adaptable to other multiphase motors also (not limited to 3-phase unipolar or 4-phase unipolar or 3-phase bipolar). Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims.