Research On MTPA Methods Of Permanent Magnet Synchronous Motor Based On Virtual DC Signal Injection

In the constant torque operating range,interior permanent magnet synchronous motors typically use MTPA control method,which minimizes the stator current magnitude while maintaining the motor torque output.However,during motor operation,magnetic saturation and cross-coupling effects cause the main parameters of the motor to vary with changes in the d-and q-axis stator currents,leading to a decrease in the effectiveness of the MTPA control method.To address this issue,this paper focuses on the MTPA control method based on virtual sine signal injection,taking into account the effects of magnetic saturation and cross-coupling in IPMSMs.Firstly,this paper injects a virtual direct current signal into the current vector angle under the dq axis,simplifying the type of injection signal to avoid signal delay caused by the use of filters.To address the slow convergence speed of the current vector angle in traditional signal injection methods,the paper improves the search conditions for the current vector angle,which increases the convergence speed of the MTPA control current vector angle and reduces delay compared to using an integrator.Next,the proposed MTPA control method based on virtual direct current signal injection is further analyzed,and a virtual direct current signal injection MTPA control method that considers changes in stator resistance is proposed.The derivation process and advantages of this method are analyzed.This method further simplifies the process of solving the current vector angle and eliminates the influence of stator resistance parameters.It can achieve more accurate MTPA control effects when stator resistance parameters fluctuate.Then,based on the proposed MTPA control method using virtual direct current signal injection,the error caused by the dynamic inductance variation along the q-axis during IPMSM operation under load changes is analyzed.The virtual direct current signal injection MTPA control method is improved by considering error compensation.Compared with the MTPA control method based on virtual direct current signal injection,the compensated method further improves the MTPA trajectory tracking accuracy without identifying parameters,and enhances the MTPA control effectiveness.Finally,simulation models were built using MATLAB/Simulink,and the simulation results were compared.The results show that:(1)The proposed MTPA control method based on virtual DC signal injection,the MTPA control method based on virtual DC signal injection considering stator resistance variation,and the improved MTPA control method based on virtual DC signal injection considering error compensation all have good response effects;(2)Under the same conditions,the improved MTPA control method based on virtual DC signal injection considering error compensation has the highest accuracy,and compared with the MTPA control method based on virtual DC signal injection and the improved method considering stator resistance variation,this method significantly improves the MTPA control accuracy;(3)The improved method considering stator resistance variation can still achieve accurate MTPA control when the stator resistance parameters change,while the other two methods have increased errors when the stator resistance changes.