Harmonic Injection-Based Torque Ripple Reduction of PMSM With Improved DC-Link Voltage Utilization

This letter proposes an improved scheme for torque ripple reduction of permanent-magnet synchronous machines (PMSMs) considering dc-link voltage utilization. Different from the previous methods, both
q
-axis and
d
-axis harmonic currents are optimized and injected. Specifically, the appropriate
q
-axis harmonic current reference is obtained through harmonic analysis of PMSM. Furthermore, the harmonic voltage control loop is included to generate the
d
-axis harmonic current reference, which can ensure that the magnitude of the voltage vector satisfies the maximum output voltage circle under the voltage constraint. The virtual signal and multiple reference frame-based proportional-integral controllers are employed to regulate the harmonic components. The effectiveness of the proposed method is validated by experimental results.