Abstract:
A motor controller circuit including an energy storage device, a bus protection circuit, an input signal selector, a combiner, a compensator, a modulator, a motor driver circuit, a commutator, a feedback circuitry and a plurality of filters, resistors, inductances, capacitances and optical isolators all contained on a single circuit board for use in controlling a motor with a minimum of cost and space requirements.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to motor control circuitry and architecture and more particularly to a low cost, high performance, high volume production single board motor controller for use for use with reaction wheel assemblies (RWAs), control moment gyroscopes (CMGs) and pointing systems,on space vehicles where size and weight play an important roles. 
     2. Description of the Prior Art 
     Honeywell presently produces a motor control system identified as the HR0610 which has met design requirements for advanced systems such as the Global series of RWAs however, with changing satellite markets, there is an ever increasing requirement for minimal cost, minimal size and high volume production without compromising quality or performance. Because of the size limitations imposed by the RWAs, the HR0610 presently requires two printed circuit boards and a plurality of electronic components of considerable size. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention draws upon the high quality and performance of the HR0610 bit includes a number of design modifications which reduce the size and weight of the controller to where it may occupy a single printed circuit board and still fit the size limitation of the RWAs. Production is also improved and cost is reduced. An example of one of the innovations is accomplished by analyzing the electronic filters heretofore composed of an three inductors and two capacitors, and determining that by utilizing four inductors and three capacitors the overall size of the filter can actually be reduced without changing its filtering ability. Utilization of hybrid circuits further reduces size and cost with the result that a vastly improved RWA implementation (called the HR14) is produced with only about 70% of the previous electronics size and weight and this is accomplished with a 40% reduction in cost. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a block diagram of the control functions of the motor controller; 
     FIG. 2 shows a block diagram of the electronics of the motor controller; and 
     FIG. 3 shows the single circuit board electronics layout. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, the block diagram for the control functions of a motor control circuit  10  is shown. A power bus  12  supplies a positive DC voltage and current on a line  14  to an electromagnetic interference filter  16  which filters out unwanted components such as noise. The filtered voltage is presented over a line  18  to an energy storage device  20 . Energy storage device  20  supplies a first DC power source, ps 1  having a first ground connection  21 , over a line  22  and operates to provide power for the motor (not shown) through a bus protection circuit  24  and a line  26  to a multiplier  28 . Because power is generated from the motor when commanding a slow down of the rotating element (detorque), the lines  14 ,  18 ,  22  and  26  are shown as double ended arrows to show that signals pass in both directions. The bus protection circuit operates to protect the internal circuits from damage that may be caused by improper operation by the user or system level faults. Energy storage  20  is also used to produce a second DC power source, ps 2 , having a second ground connection  29 , over a line  30  which operates to provide power to the components of a control circuit made up of a gate array and hybrid circuit  32 , to be described. The two ground references  21  and  29  operate to provide electrical isolation between the control circuit  32  and the motor. 
     Custom hybrid circuit  32  constitutes an RWA control with an innovative arrangement of control components that reduces the size and cost of the previous arrangement by a design which allows ease of reconfiguration between various user requirements such as torque scale It is known that microelectronics design based upon hybrid implementation requires far fewer parts than a discrete design. 
     A first desired torque signal is presented to a first input filter  36  in hybrid circuit  32  on a line  38 . A second desired torque signal may be presented to a second input filter  40  in hybrid circuit  32  on a line  42 . Other torque input command signals, which may be digital, may also be supplied via a shift register and pulse DAC, shown as box  44 , on a line  46 . After filtering, these desired command torque signals are presented to a selector  50  by way of lines  52 ,  54  and  56  respectively. Selector  50  operates to select one of the desired filtered torque command signals and present it via line  58  to a combiner  60 . Combiner  60  also has a feedback input on a line  62  which contains the wanted output from the motor and unwanted errors and noise from the system. Combiner  60  operates to combine the inputs on lines  58  and  62  and to present the combined signal via a line  64  to a compensator  66 . Compensator  66  operates to nullify the error signals on line  64  by producing an appropriate signal which is presented to a pulse width modulator  70 . Pulse width modulator  70  operates to change the command signal so as to produce an average command on a line  72 . The average command signal is used to control the motor at a reduced voltage without the power dissipation encountered by such devices as a linear amplifier. The average command signal on line  72  is presented to a commutator  74  which operates to provide a motor drive signal on a line  76  which is characterized for presentation to the proper winding of the motor. Since the motor and its associated components are supplied with power on line  22  which has a reference ground  21  of the power source ps 1 , and since the components in hybrid circuit  32  are supplier with power on line  30  which has a reference ground  29  of power source ps 2 , the converter  78  is used to receive the proper winding signal on line  76  and to convert the signal from one having the reference ground  29  to one having the reference ground  21 . The signal from converter  78  is presented to the multiplier  28  via line  80  to provide the final motor drive signal on line  82 . Line  84  is shown leading from the motor back to the hybrid circuit  32 . This feedback signal passes through a converter  86 , comprising a scaling circuit  87 , a modulator  38  and a demodulator  89 , which together operate to change the signal on line  84  which is referenced to ground  21  to the feedback signal on line  62  which is referenced to ground  29  for use in the hybrid circuit  32 . This signal is presented on a line  90  to the feedback line  62  and also to a scaling circuit  92  to produce a motor current telemetry (TLM) signal at an output  94 . 
     FIG. 2 shows the electrical block diagram for the motor control circuit of the present invention. In FIG. 2, the power bus input  100  is shown passing through in-line filters  102  and a power switching circuit  104  which is turned on and off by a relay control  106  from an on/off input  108  (not shown in FIG. 1) and produces an output on a line  110  which is connected to an EMI filter  112 . EMI filter  112  is connected to an energy storage circuit  114  and from there to a bus protection circuit  116  in a manner similar to the arrangement of FIG.  1 . Line  115  is connected by a line  118  to a secondary power supply box  119  (not shown in FIG. 1) which provides various voltages shown by references a, b, c and d having ground references  21  or  29  as required for use with an RWA Control Hybrid circuit  120  and other equipment connected to the system. In the preferred embodiment, the a and b are +5 volts and the c and d voltages are ±12 volts. The RWA Control Hybrid circuit  120  contains the elements shown by functional block “O/R Voltage” (over/under voltage), “Input Filter”, “Demod” (demodulator), “Mod” (modulator), “CRNT Loop Comp” (current loop compensation), “Bus Protct” (bus protection), “PWM” (pulse width modulation) and “Sense Amp” (sense amplifier). It will be noted that the “Bus Protection” circuit is shown both inside and outside of the hybrid box  120 . The portion inside is a “Pre-drive” circuit while the portion outside identified with reference numeral  116  is the “Final Drive” circuit which is connected to a Motor Driver circuit  122 . 
     An analog command  124  is shown in FIG. 2 connected to an OR function  126  and a digital torque command  128  is shown connected to circuitry shown as the “other” box of FIG.  1  and comprises an amplifier  130 , a telemetry register  132  and a digital to analog converter  134  the output of which is also connected to OR function  126 . OR function  126  selects one of the commands and presents it to the hybrid circuitry  120  via input  127 . 
     The commutator  74  of FIG. 1 is shown in FIG. 2 as a commutation tachometer and overspeed box  180  which receives an output from the hybrid circuit  120  on a line  142 , HALL position information from box  150  through line  152 , and a clock signal input identified as 8 MHz. The output signals of the hybrid circuit  120  are, as explained above, electrical signals referenced to a ground  29 . The Commutation tachometer and overspeed box  180  is therefore connected to an optical isolator  144  which converts the electrical signals to optical signals and then transfers them to electrical signals again but referenced to ground  21  to produce the outputs  146  leading to the motor driver  122 . 
     Bus protect circuit  116  is connected to the motor driver circuit  122  which contains the pre-driver circuits and the three phase outputs for the motor winding  124 A,  124 B and  124 C. respectively. Hall sensors shown as box  150  provide feedback to the commutator  180  over a line  152 , not shown in FIG.  1 . 
     The current in the windings  124 A,  124 B and  124 C is sensed by current sensors shown as box  154  and are presented to a current sensing amplifier in hybrid circuit  120  over a line  156 . These form part of the scaling function of box  87  of FIG.  1 . An output of the modulator  88  and demodulator  89  of FIG. 2 is presented on a line  158  to an amplifier  160  and then to an output identified as Motor Current Telemetry  162  which provides as signal for telemetry which enables the operator to read the motor currents. In similar fashion, and output from the commutator, tachometer and overspeed circuit  180  is presented to an amplifier  166  and then to an output identified as tachometer  168  to enable the operator to monitor the motor speed. Finally, an output from the commutator, tachometer and overspeed circuit  180  is presented to a telemetry register  170  and to an buffer  172  to an output identified as Digital telemetry  174  to enable the operator to monitor the digital signals. 
     The elements of FIG. 2 have been assembled on a single circuit board having dimensions of approximately 10½ inches by 10½ inches in accordance with the present invention and this may be seen in FIG. 3. A circuit board  200  is shown containing the RWA Control Hybrid components  120  of FIG. 2 in a hybrid circuit  202  in FIG.  3 . The in line filters  102  and the EMI filter  112  of FIG. 2, which have been improved from the prior art as described above, are shown as circles and boxes with reference numerals  204 . The secondary power supply hybrid  122  of FIG. 2 is shown as hybrid circuitry  206  In FIG.  3 . The motor driver circuit  122  of FIG. 2 is shown as circuitry  208  in FIG.  3 . The hall sensors  150  of FIG. 2 are not shown in FIG.  3 . The current sensing resistors  154  of FIG. 2 are shown as Z shaped boxes  212  in FIG.  3 . The telemetry register  170 , the command registers  132 , the digital to analog converter  134  of FIG. 2 are shown as box  216  in FIG.  3 . The relay controls  106  of FIG. 2 are shown as components  218  in FIG.  3 . 
     Many other components, not shown in FIG. 2 including miscellaneous capacitors, resistors, amplifiers and the like are also shown on board  200  in FIG. 3 but have not been numbered so as to provide better clarity. Together they provide a single circuit board with all of the components necessary to provide the desired motor control in a minimum of space and cost. Board  200  is sized to fit within a space attached to the RWA by mounts to provide a neat and compact structure. User interface is provided through connectors  220 . 
     It is therefore seen that we have provided a minimal cost, minimal size and high volume production device without compromising quality or performance. Further modifications of the preferred embodiment of the present invention my occur to those skilled in the art and we do not wish to be limited to the specific details used in describing the invention.