Vector control of five-phase synchronous reluctance machine with the third harmonic current injections for high specific torque.

摘要

Three-phase AC machines with sinusoidal winding distributions are widely used in all industrial fields. However, an inherent disadvantage is obvious in that the iron is not fully utilized. Because the airgap MMF is nearly sinusoidally distributed, most of the iron is not saturated to the desired level. High order harmonics need to be injected to otherwise fundamental stator current in order to achieve rectangular airgap flux distribution. Unfortunately, the third harmonic current, the dominant high order component, cannot flow through a three-phase three-wire system.; In contrast, five-phase AC motors with concentrated windings can successfully accommodate the third harmonic. Among five-phase machines, the synchronous reluctance machine with salient poles matches a rectangular flux density due to its special rotor geometry. It thus becomes a superior motor choice. Therefore, the exploration of the five-phase synchronous reluctance machine has aroused great interest.; In this research, a systematic approach is utilized to analyze the performance of the proposed five-phase synchronous reluctance machine while it is being excited with the fundamental plus the third harmonic current injections. First of all, the evaluation of multiphase machines establishes a foundation for the entire work. Harmonic analysis is employed as a helpful tool. Linear investigation of torque production, on the other hand, validates that the torque density can be increased by the third harmonic current injection. In addition, a mathematical model is derived to simplify the analysis. A vector control algorithm is developed to confirm the enhanced operation of the motor. The motor model is refined to operate at a degraded performance level when one or more phases are lost. Finally, simulation and experimental results verify that the third harmonic current injections could generate high specific torque.