Virtual Multiphase Drive-Based Harmonic Current Injection Approach for PMSMs With Distorted Back-EMFs

This letter focuses on harmonic current regulation for permanent magnet synchronous machines (PMSMs) with distorted back electromotive forces (EMFs). The key is that an improved harmonic injection scheme is proposed based on a virtual nine-phase PMSM system to decompose harmonic currents without digital filters as in traditional approaches. This enables independent harmonic current regulation with conventional proportional–integral controller in multiple synchronous reference frames (MSRFs) while minimally affecting the dynamic performance of the system. Moreover, the quantitative effect of distorted back EMFs on torque performance is analyzed using magnetic co-energy theory. The harmonic current reference is derived in harmonic subspace with MSRFs for reducing torque ripple. Ultimately, the effectiveness of the proposed scheme is validated through experimental results under both the steady-state and dynamic conditions.