SWITCH ARRAY FOR USE IN MOTOR CONTROL

Abstract

An switch array for use in a motor control circuit with a power source, controller and a motor includes a plurality of bidirectional switches positioned between the power source and the motor, wherein the bidirectional switches are PWM controlled by high speed control signals from the controller to provide power from the power source to the motor as desired, wherein the switch array is positioned substantially adjacent to the motor. The power source may be a three phase AC power source. The switches are preferably bidirectional gallium nitride (GaN) switches.

Description

BRIEF DESCRIPTION OF THE DRAWING(S)

FIG. 1 is an illustration of a convention motor control circuit.

FIG. 2 is an illustration of the effect of noise on a current waveform of the circuit in FIG. 1.

FIG. 3, is an illustration of the effect of noise on the voltage waveform of the circuit of FIG. 1.

FIG. 4 is an illustration of a switch array for use in a motor control circuit in accordance with an embodiment of the present invention.

FIG. 5 is a more detailed illustration of the switch array and power source of FIG. 4.

FIG. 6 illustrates the desired current directions in the motor of FIG. 5 to produce a desired torque.

FIG. 7 is an illustration of the waveforms in each of the legs of the motor of FIG. 6.

FIG. 8 is an illustration of a switch array for use in a motor control circuit in accordance with another embodiment of the present invention.

FIG. 9 is an illustration of a controller for use in the circuits of FIGS. 4, 5 and/or 8.

FIG. 10 is an illustration of a switch array for use in a motor control circuit in accordance with another embodiment of the present invention.

FIG. 11 a illustrates the desired current directions in the motor of FIG. 10 to produce a desired torque

FIGS. 11 b-c illustrate alternative switching arrangements in the switch array of FIG. 10 to provide the desired torque of FIG. 11b.

FIG. 12 is an illustration of the waveforms in each of the legs of the motor.

FIG. 13 is an illustration of the waveforms in each of the legs of the motor of FIGS. 11b and 11c.

FIG. 14 is an illustration of waveforms in each of the legs of the motor in FIG. 10 when current is allowed to drain from the windings in each of the legs.

FIG. 15 is an illustration of a switch array for use in a motor control circuit in accordance with another embodiment of the present invention.

Claims

1. A switch array for use in a motor control circuit with a power source, controller and a motor, the switch array comprising: a plurality of bidirectional switches positioned between the power source and the motor, wherein the bidirectional switches are PWM controlled by high speed control signals from the controller to provide power from the power source to the motor as desired, wherein the switch array is substantially adjacent to the motor.

2. The switch array of claim 1, wherein the motor further comprises: a first leg including a first coil;a second leg including a second coil; anda third leg including a third coil;wherein each leg of the first leg, second leg and third leg is positioned 120 degrees offset from the other legs.

3. The switch array of claim 2, wherein a first input switch of the plurality of bidirectional switches is position between the power source and the first leg of the motor;a second input switch of the plurality of bidirectional switches is positioned between the power source and the second leg of the motor; anda third input switch of the plurality of bidirectional switches is positioned between the power source and the third leg of the motor.

4. The switch array of claim 3, wherein a first recirculation switch of the plurality of bidirectional switches is positioned across the first winding;a second recirculation switch of the plurality of bidirectional switches is positioned across the second winding; anda third recirculation switch of the plurality of bidirectional switches is positioned across the third winding.

5. The switch array of claim 4, wherein first, second and third input switches and the first, second and third recirculation switches are bidirectional semiconductor switches.

6. The switch array of claim 5, wherein first, second and third input switches and the first, second and third recirculation switches are bidirectional gallium nitride(GaN) switches.

7. The switch array of claim 5, wherein the power source provides single phase AC current and voltage.

8. The switch array of claim 5, wherein the power source further comprises: a plurality of low speed switches operable to provide low speed switching such that at least one of a switched voltage signal and a switched current signal is provided from the power source.

9. The switch array of claim 8, wherein a frequency of the switched voltage signal or the switched current signal provided by the power source is substantially higher than a maximum rotational rate of the motor.

10. The switch array of claim 9, wherein four low speed switches are provided and wherein the switching provided by the four low speed switches provides the switched voltage signal or the switched current signal with a frequency that is sufficiently low to allow edge control to prevent substantial noise in the switched voltage signal or switched current signal.

11. The switch array of claim 9, wherein two low speed switches are provided and wherein the switching provided by the two low speed switches provides the switched voltage signal or the switched current signal with a frequency that is sufficiently low to allow edge control to prevent substantial noise in the switched voltage signal or the switched current signal.

12. The switch array of claim 11, wherein the power source further comprises a low pass filter operative to reduce edge noise in the switched voltage signal or switched current signal.

13. The switch array of claim 7, wherein the controller further comprises: a position controller operable to determine a position of a rotor of the motor and to provide position information;a velocity controller operable to determine a velocity of the motor and to provide velocity information; anda torque loop operable to determine the torque of the motor and to provide the high speed control signals to drive the bidirectional switches of the switch array based on the torque of the motor, the position information from the position controller and the velocity information from the velocity controller.

14. The switch array of claim 13, wherein the controller further comprises a high speed communication device operable to send the high speed control signals to the switch array and to receive feedback information regarding the motor.

15. A switch array for use in a motor control circuit including a three phase AC power source, a controller and a motor, the switch array further comprising: a plurality of bidirectional switches positioned between the three phase AC power source and the motor, wherein the bidirectional switches are PWM controlled by high speed control signals from the controller to provide power from the three phase AC power source to the motor as desired, wherein the switch array is positioned substantially adjacent to the motor.

16. The switch array of claim 15, wherein the motor further comprises: a first leg including a first coil;a second leg including a second coil; anda third leg including a third coil;wherein each leg of the first leg, second leg and third leg is positioned 120 degrees offset from the other legs.

17. The switch array of claim 16, wherein a first input switch of the plurality of bidirectional switches is position between a first phase line from the three phase AC power source and the first leg of the motor;a second input switch of the plurality of bidirectional switches is positioned between a second phase line from the three phase AC power source and the second leg of the motor; anda third input switch of the plurality of bidirectional switches is positioned between a third phase line from the three phase AC power source the power source and the third leg of the motor.

18. The switch array of claim 17, wherein a first recirculation switch of the plurality of bidirectional switches is positioned across the first winding;a second recirculation switch of the plurality of bidirectional switches is positioned across the second winding; anda third recirculation switch of the plurality of bidirectional switches is positioned across the third winding.

19. The switch array of claim 18, wherein the first, second and third input switches and the first, second and third recirculation switches are bidirectional semiconductor switches

20. The switch array of claim 19, wherein the first, second and third input switches and the first, second and third recirculation switches are gallium nitride (GaN) switches.

21. The switch array of claim 17, wherein the controller further comprises: a position controller operable to determine a position of a rotor of the motor and to provide position information;a velocity controller operable to determine a velocity of the motor and to provide velocity information; anda torque loop operable to determine the torque of the motor and to provide the high speed control signals to drive the bidirectional switches of the motor based on the torque of the motor, the position information from the position controller and the velocity information from the velocity controller.

22. The switch array of claim 18, wherein the controller further comprises a communication device operable to send the high speed control signals to the switch array and to receive feedback information regarding the motor.