A Muti-Harmonic Subspace Control of Open-End Winding Nine-Phase PMSM with Third Harmonic Current Injection

Inject third harmonic current into open-end winding nine-phase PMSM can improve the torque density. From the perspective of vector space decoupling, established the mathematical model of open-end winding nine-phase PMSM in the rotation coordinate, and the mechanism of increasing torque by injecting third harmonic current is described. A muti-harmonic subspace control method is proposed to realize the closed-loop control of each harmonic plane current. Compared the advantages and disadvantages of equal amplitude and equal inverter capacity, the principle of equal inverter capacity is chosen to derived the ratio of third harmonic current injection that maximize the output torque. Finally, the enhancement effect of third harmonic current on electromagnetic torque is verified by simulation, and the copper consumption of the motor before and after harmonic injection is analyzed.