Multiple reference frame-based current harmonic control for interior PMSMs considering motional EMF

For permanent magnet synchronous machines (PMSMs), current harmonics need to be controlled under two kinds of conditions. Under the first condition, the current harmonics caused by the non-sinusoidal back-electromotive force (EMF) and the dead time of inverters should be suppressed. Under the second condition, specific current harmonics should be injected to suppress the torque ripple of motors. Therefore, the accurate control of current harmonics is critical. It has been found that the original multiple reference frame (MRF)-based control algorithm cannot effectively achieve the control of current harmonics at high speeds. For the currents in MRFs, motional EMF was dominant rather than induced EMF at higher speeds. As a result, the original MRF-based control algorithm does not work at high speeds. To solve this problem, this paper proposed a novel MRF-based control algorithm that considers motional EMF. Furthermore, this paper achieved decoupling control of the current harmonics in MRFs for interior PMSMs. With the proposed control algorithm, the current harmonics of interior PMSMs can be controlled at both high and low speeds. Under the influence of non-sinusoidal back EMF and the dead time of the inverter, the effect of current harmonic control was verified on a laboratory test bench.