To address the issues of current harmonics and torque pulsation caused by the inverter′s nonlinear factors，which reduce the MTPA control accuracy of IPMSM，this paper proposes a collaborative control strategy that combines virtual DC signal injection MTPA with a proportionalintegral resonant controller. First，the virtual DC signal injection method injects a virtual DC signal into the d-q axis feedback current，and simultaneously calculates the virtual power response using voltage information to achieve precise tracking of the optimal current vector angle，thereby avoiding current and torque pulsation. Second，a quasi-resonant controller is introduced，which is combined with a traditional current loop PI controller to form a PIR composite controller. By leveraging its high gain characteristics for specific harmonic frequencies (such as 5th and 7th)，it compensates for the low-frequency harmonics introduced by inverter nonlinearity. Additionally，the introduction of the PIR controller further improves the quality of voltage and current waveforms，enhancing the precision of MTPA control. Together，these two components form a dual closed loop of harmonic suppression-efficiency optimization.The experimental results show that the proposed cooperative control strategy can effectively suppress the 5th and 7th harmonics and reduce the total harmonic distortion rate of current under different speed scenarios; under the same load torque conditions，compared to traditional MTPA control and virtual DC signal injection MTPA control，the proposed collaborative control strategy requires lower current values and achieves higher MTPA control accuracy.