COMPARATIVE STUDY OF IPM SYNCHRONOUS MACHINES WITH DIFFERENT SALIENCY RATIOS CONSIDERING EVS OPERATING CONDITIONS

In this paper, based on different saliency ratios ρ, three interior permanent magnet (IPM) synchronous machines respectively owning a large ρ, a low ρ and an inverse ρ are proposed for the potential applications of electrical vehicles (EVs). To grasp the impacts of saliency ratio on machine performances, comparative studies are conducted at low speed operation (constant torque region) and high speed operation (constant power region), respectively. In particular, the overload capability referring to magnet demagnetization is emphasized in low-speed heavy-duty operation region. And in high speed, the constant power speed range (CPSR) and high efficiency range are investigated. The main results put in evidence the different behaviors of the three machines in terms of EVs operating conditions. Though all three machines reveal considerable behaviors in CPSR, the inverse saliency ratio machine shows a larger high efficiency region and extends the high efficiency region to a wider speed-and-torque range due to its unique characteristic of Lq < Ld.