Electrothermal Analysis of Induction Motor With Compound Cage Rotor Used for PHEV

A new kind of induction motor with compound cage rotor (IMCCR) is proposed in this paper, in which rotor bars are composed of upper parts made of alloy (conductor for electric and magnetic) and lower parts made of cast aluminum. Calculation models for IMCCR electromagnetic field and whole region (including stator and rotor) temperature field analyses are established. From a motor electromagnetic analysis using the finite-element method, loss distributions are obtained, which are taken as the heat source in thermal analysis. In this paper, the starting and thermal performances of IMCCR operating under rated load are studied. From the comparison of the obtained results with test data, it can be seen that IMCCR would be a better choice for the driving system in electrical vehicles (EVs) and plug-in hybrid EVs (PHEVs). Furthermore, the influences of compound bar material on motor temperature distribution are analyzed, which would be helpful for the research on electrical materials used in machines. Considering the working conditions of motor used in PHEV and EV, the effects of ambient temperature and output load on motor thermal performance also have been studied.