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

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.

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.