Motor control system, controller, and method

1. A method of controlling an electric motor, the method comprising:

determining a PWM (pulse width modulation) control signal;

analyzing the PWM control signal to determine if duty-cycle components of the PWM control signal are within a threshold amount of each other;

applying duty-cycle blanking to the PWM control signal, if the duty-cycle components of the PWM control signal are within the threshold amount of each other, to generate an adjusted PWM control signal; and

controlling the electric motor with the adjusted PWM control signal to limit parasitic effects;

wherein the PWM control signal includes a first duty-cycle component and a second duty-cycle component;

wherein the first duty-cycle component includes a smaller duty cycle than the second duty-cycle component;

wherein applying duty-cycle blanking includes advancing the first duty-cycle component by a first amount corresponding to half of a total of the first duty-cycle component added with the second duty-cycle component less the threshold amount, to generate an adjusted first duty-cycle component of the adjusted PWM control signal; and

wherein applying duty-cycle blanking includes delaying the second duty-cycle component by a second amount corresponding to half of a total of the first duty-cycle component added with the second duty-cycle component plus the threshold amount, to generate an adjusted second duty-cycle component of the adjusted PWM control signal.

2. The method of claim 1 , wherein duty-cycle blanking is applied to the PWM control signal only if the PWM control signal includes a voltage above a threshold voltage; and the threshold voltage is a variable percentage of a maximum control voltage.

3. The method of claim 1 , wherein duty cycle blanking includes one or both of delaying and advancing at least one of the duty-cycle components of the PWM control signal.

4. The method of claim 1 , wherein the duty-cycle components of the PWM control signal include a third duty-cycle component.

5. The method of claim 4 , wherein analyzing the PWM control signal includes:

comparing at least one of the first duty-cycle component, the second duty-cycle component, and the third duty-cycle component to a nominal value; and

determining that one of the first duty-cycle component, the second duty-cycle component, and the third duty-cycle component is substantially equal to the nominal value, is not expected to be materially affected by parasitic effects, and does not need to be adjusted; and

determining that at least one other duty-cycle component needs to be adjusted if the at least one other duty-cycle component is not substantially equal to the nominal value.

6. The method of claim 5 , wherein the at least one other duty-cycle component includes two components.

7. The method of claim 5 , wherein duty cycle blanking includes adjusting the at least one other duty-cycle component.

8. The method of claim 7 , wherein adjusting the at least one other duty-cycle component includes one or both of delaying the at least one other duty-cycle component and advancing the at least one other duty-cycle component.

9. The method of claim 1 , wherein controlling the electric motor with the adjusted PWM control signal to limit parasitic effects includes controlling operation of a plurality of electrical switches configured to selectively provide an electric connection between a power source and the electric motor.

10. The method of claim 9 , wherein the plurality of electrical switches includes a first set of switches, a second set of switches, and a third set of switches; and the first duty-cycle component of the adjusted PWM control signal controls the first set of switches, the second duty-cycle component of the adjusted PWM control signal controls the second set of switches, and a third duty-cycle component of the adjusted PWM control signal controls the third set of switches.

11. The method of claim 9 , wherein controlling operation of the plurality of electrical switches includes controlling the plurality of electrical switches with the adjusted PWM control signal to limit parasitic effects.

12. The method of claim 11 , wherein controlling the plurality of electrical switches with the adjusted PWM control signal includes operating the plurality of electrical switches such that certain switches do not close at substantially the same time or open at substantially the same time.

13. The method of claim 1 , wherein the threshold amount corresponds to about 2% of a period of the PWM control signal.

14. A control system, comprising:

a plurality of switches configured to electrically connect a power source with an electrical component; and

an electronic controller;

wherein the electronic controller is configured to:

receive one or more inputs;

generate a PWM (pulse width modulation) control signal, according to the one or more inputs, for controlling the plurality of switches;

analyze the PWM control signal to determine if components of the PWM control signal are within a threshold amount of each other;

adjust the PWM control signal, if the components are within the threshold amount, to produce an adjusted control signal; and

control the plurality of switches via the adjusted control signal to limit parasitic effects;

wherein the PWM control signal includes a first duty-cycle component and a second duty-cycle component;

wherein the first duty-cycle component includes a smaller duty cycle than the second duty-cycle component;

wherein the adjusted control signal includes applying a duty-cycle blanking advancing the first duty-cycle component by a first amount corresponding to half of a total of the first duty-cycle component added with the second duty-cycle component less the threshold amount, to generate an adjusted first duty-cycle component of the adjusted PWM control signal; and

wherein applying the duty-cycle blanking further includes delaying the second duty-cycle component by a second amount corresponding to half of a total of the first duty-cycle component added with the second duty-cycle component plus the threshold amount, to generate an adjusted second duty-cycle component of the adjusted PWM control signal.

15. The control system of claim 14 , wherein the adjusted control signal includes at least one adjusted component and an unadjusted component.

16. The control system of claim 15 , wherein the at least one adjusted component is one or both of delayed and advanced.

17. The control system of claim 14 , wherein the electrical component includes a three-phase alternating current motor.

18. The control system of claim 14 , wherein the plurality of switches includes a first switch, a second switch, a third switch, a fourth switch, a fifth switch, and a sixth switch; the adjusted control signal includes a first signal component, a second signal component, and a third signal component; the first signal component corresponds to the first switch and the second switch; the second signal component corresponds to the third switch and the fourth switch; and the third signal component corresponds to the fifth switch and the sixth switch.

19. A non-transitory computer readable storage medium storing instructions, which when executed by a processor of an electronic controller, causes the electronic controller to:

receive one or more inputs;

generate a PWM (pulse width modulation) control signal for controlling an electrical component according to the one or more inputs;

analyze the control signal to determine if two components of the control signal are within a threshold amount of each other;

adjust the control signal, if the two components are within the threshold amount, to produce an adjusted control signal; and

control a plurality of electrical switches via the adjusted control signal to limit parasitic effects;

wherein the PWM control signal includes a first duty-cycle component and a second duty-cycle component;

wherein the first duty-cycle component includes a smaller duty cycle than the second duty-cycle component;

wherein the adjusted control signal includes applying a duty-cycle blanking advancing the first duty-cycle component by a first amount corresponding to half of a total of the first duty-cycle component added with the second duty-cycle component less the threshold amount, to generate an adjusted first duty-cycle component of the adjusted PWM control signal; and

wherein applying the duty-cycle blanking further includes delaying the second duty-cycle component by a second amount corresponding to half of a total of the first duty-cycle component added with the second duty-cycle component plus the threshold amount, to generate an adjusted second duty-cycle component of the adjusted PWM control signal.