Novel hybrid excitation permanent magnet vernier machines

Abstract

Permanent magnet (PM) machines possess the merits of high torque density and high efficiency which is very suitable for some applications such as electric vehicles (EVs) [1]-[4]. Over the years, the surface PM and interior PM types, have been extensively studied and developed. The 2004 prius interior PM machine with the advantages of high torque density and wide speed range has been built and applied successfully in hybrid EVs. Recently, PM vernier (PMV) machines derived from magnetic gears are acknowledged that it can offer higher torque density than conventional one [4]-[6]. Unfortunately, similar to conventional PM machines, the PMV ones also suffer from relatively low flux adjusting efficiency and poor performance at high speed range due to the uncontrollable PM magnetic field. A flux controllable PMV machine has been proposed to improve these problems by the introduction of DC field excitation windings [6]. Although the flux controllable PMV machine definitely combines the merits of high torque density and wide speed range, its flux adjustment capability is still limited because the flux by the field excitation windings goes through the high magnetic reluctance of PMs. In addition, it suffers from the problems of mechanical integrity and thermal instability since the PMs are located on the rotor. To solve these problems in the existing flux controllable PMV machine, two novel hybrid excitation PMV machines with surface and V shape PMs, termed as the hybrid excitation surface PM vernier (HE-SPMV) and hybrid excitation V shape interior PM vernier (HE-VIPMV) machines, will be proposed in this paper.