Maximum Torque Per Ampere Control For Interior Permanent Magnet Synchronous Motors Based On Signal Injection Method

Because of its high torque density,high power density and high efficiency,interior permanent magnet synchronous motor is commonly used as the main drive motor of electric vehicles.Maximum torque per ampere technology is often used to control the interior permanent magnet synchronous motor to enhance the torque output capability and achieve higher efficiency.In practical applications,the maximum torque per ampere is more susceptible to the change of motor parameters than the operating point,which poses a challenge for precise tracking of the optimal point.The signal injection method in the control of maximum torque per ampere does not need to consider the variation of motor parameters,so it has high research value.In this paper,the maximum torque per ampere control strategy based on signal injection method is studied.Firstly,the maximum torque per ampere control strategy based on formula method is introduced,and the approximate expression of the optimal stator current vector angle is given.Secondly,a control strategy of maximum torque per ampere based on signal injection method is introduced.The basic idea of the control strategy is to inject a high frequency sinusoidal small signal into the motor voltage vector.The injected signal will cause high frequency fluctuation of stator current and flux.After signal processing and closed-loop adjustment,the optimal stator current vector reference angle is provided for the motor current control,achieving the effect of tracking the operating point of the current maximum torque per ampere.The simulation results show that the control strategy is correct and effective.Finally,a 2.2kW interior permanent magnet synchronous motor experimental platform is built,and the comparative experiments are carried out.The experimental results show that,compared with id=0 control,the two kinds of maximum torque per ampere control can improve the current utilization ratio of the interior permanent magnet synchronous motor in varying degrees,while the signal injection method of maximum torque per ampere control can improve the operation efficiency of the motor more effectively,enhance its torque output ability,and have better dynamic and steady-state performance.