Comparison and analysis of two power topologies for four-phase SRM

Abstract

Power converter topology is an important part of the switched reluctance motor drive, and it occupies an important proportion in the performance and cost of the entire SRD. The asymmetric half-bridge converter topology is the most common power converter topology, with the strongest independence between phase windings, flexible chopping mode, and simple control. The 2(N+1) converter topology reduces the switching tube on its basis, which can effectively reduce the volume of the power converter. However, at the same time it also reduces the independence of each phase. Current freewheeling and difficult demagnetization may increase the difficulty of control. Through the linear model on the chain-angle, the magnetic flux width range of the 2(N+1) converter topology under current chopping control and angle control positions is derived. In this paper, the finite element simulation of the control parameters of a four-phase 8/6 SRM is carried out on the ANSYS Maxwell simulation platform. Under the same motor model, when using an asymmetric half-bridge circuit and a 2(N+ 1) converter circuit, compare the output average torque and current waveforms at different speeds. Since the current freewheeling time of the 2(N+ 1) converter circuit is longer, the system power density is reduced. At the same time, due to the limitation of the conduction width of the 2(N+1) converter circuit, the phase current is smaller than the asymmetric half-bridge circuit, and the efficiency is slightly lower. Finally, an experimental platform was built to compare the effects of the two power converters on the performance of the motor system through experiments, and the simulation analysis verified that the simulation was correct.