Electric motor control method and device, system, and electric vehicle

1. An electric motor control method performed by a controller, the method comprising:

obtaining an input power and an output power of an electric motor;

determining a loss power based on the input power and the output power;

determining a target d-axis current of the electric motor, wherein the target d-axis current is calculated by a calculation module based on the loss power, the calculation module comprises a tracking differentiator, and the calculation module operates in the controller; and

determining a duty ratio based on the target d-axis current and a preset q-axis current, and inputting the duty ratio into an inverter so that the inverter drives, based on the duty ratio, the electric motor to operate.

2. The method according to claim 1 , wherein the obtaining an input power and an output power of an electric motor comprises:

obtaining an input voltage and an input current of the electric motor, and obtaining the input power based on the input voltage and the input current; and

obtaining an output torque and an output rotation speed of the electric motor, and obtaining the output power based on the output torque and the output rotation speed.

3. The method according to claim 1 , wherein the calculating a loss power based on the input power and the output power comprises:

using a difference between the output power and the input power as the loss power.

4. The method according to claim 1 , wherein the determining a duty ratio based on the target d-axis current and a preset q-axis current comprises:

comparing the target d-axis current with a current d-axis current in the inverter, comparing the preset q-axis current with a current q-axis current in the inverter, and determining the duty ratio based on the target d-axis current and the preset q-axis current if a deviation between the target d-axis current and the current d-axis current is greater than a first preset threshold and/or a deviation between the preset q-axis current and the current q-axis current is greater than a second preset threshold.

5. The method according to claim 1 , wherein the tracking differentiator is constructed based on a second-order transfer function, wherein the tracking differentiator comprises one input end and two output ends, a first output end is configured to track dynamic characteristics of the input loss power, and a second output end is configured to differentiate a signal output by the first output end.

6. The method according to claim 5 , wherein the tracking differentiator is:

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wherein, v 0 (k) is an input to the tracking differentiator, and is a loss power corresponding to a kth moment; x 1 (k+1) is a first output from the tracking differentiator at a (k+1) th moment, and is used to track dynamic characteristics of the loss power at the kth moment; x 2 (k+1) is a second output from the tracking differentiator at a (k+1) th moment, and is used to differentiate the first output; r is a speed factor; and h is a filter factor.

7. An electric motor control device, comprising:

a first power calculation module, configured to obtain an input power and an output power of an electric motor;

a second power calculation module, configured to determine a loss power based on the input power and the output power;

a current tracking module, configured to determine a target d-axis current of the electric motor, wherein the target d-axis current is calculated by a calculation module based on the loss power, the calculation module comprises a tracking differentiator, and the calculation module operates in the control device; and

an efficiency optimization module, configured to determine a duty ratio based on the target d-axis current and a preset q-axis current, and input the duty ratio into an inverter so that the inverter drives, based on the duty ratio, the electric motor to operate.

8. An electric motor drive system, wherein the drive system comprises the electric motor control device according to claim 7 .

9. An electric vehicle, wherein the electric vehicle comprises the electric motor drive system according to claim 8 .

10. A non-transitory computer-readable storage medium storing a computer-executable instruction that, when executed by a computer, causes an electric motor control device to perform an electric motor control method, the method comprising:

obtaining an input power and an output power of an electric motor;

determining a loss power based on the input power and the output power;

determining a target d-axis current of the electric motor, wherein the target d-axis current is calculated by a calculation module based on the loss power, the calculation module comprises a tracking differentiator, and the calculation module operates in the control device; and

determining a duty ratio based on the target d-axis current and a preset q-axis current, and inputting the duty ratio into an inverter so that the inverter drives, based on the duty ratio, the electric motor to operate.

11. The non-transitory computer-readable storage medium according to claim 10 , wherein the obtaining an input power and an output power of an electric motor comprises:

obtaining an input voltage and an input current of the electric motor, and obtaining the input power based on the input voltage and the input current; and

obtaining an output torque and an output rotation speed of the electric motor, and obtaining the output power based on the output torque and the output rotation speed.

12. The non-transitory computer-readable storage medium according to claim 10 , wherein the calculating a loss power based on the input power and the output power comprises:

using a difference between the output power and the input power as the loss power.

13. The non-transitory computer-readable storage medium according to claim 10 , wherein the determining a duty ratio based on the target d-axis current and a preset q-axis current comprises:

comparing the target d-axis current with a current d-axis current in the inverter, comparing the preset q-axis current with a current q-axis current in the inverter, and determining the duty ratio based on the target d-axis current and the preset q-axis current if a deviation between the target d-axis current and the current d-axis current is greater than a first preset threshold and/or a deviation between the preset q-axis current and the current q-axis current is greater than a second preset threshold.

14. The non-transitory computer-readable storage medium according to claim 10 , wherein the tracking differentiator is constructed based on a second-order transfer function, wherein the tracking differentiator comprises one input end and two output ends, a first output end is configured to track dynamic characteristics of the input loss power, and a second output end is configured to differentiate a signal output by the first output end.

15. The non-transitory computer-readable storage medium according to claim 14 , wherein the tracking differentiator is:

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wherein, v 0 (k) is an input to the tracking differentiator, and is a loss power corresponding to a k th moment; x 1 (k+1) is a first output from the tracking differentiator at a (k+1) th moment, and is used to track dynamic characteristics of the loss power at the k th moment; x 2 (k+1) is a second output from the tracking differentiator at a (k+1) th moment, and is used to differentiate the first output; r is a speed factor; and h is a filter factor.