Research On Combined-pole V-shape Interior Permanent-magnet Synchronous Machine

Benefitting from reluctance torque produced by the asymmetry of the rotor magnetic circuit, interior permanent-magnet synchronous machines(IPMSM) have the advantages of high power density and salient field-weakening performance, which makes them popular in electric vehicles(EVs) field. However, conventional IPMSMs have the shortcomings of non-sinusoidal air-gap flux density, high expense and low demagnetization withstand ability. Aiming at those disadvantages, the paper proposes a combined-pole V-shape interior permanent-magnet synchronous machine(CPVIPMSM). Composed of two magnetic materials, which are neodymium iron boron and ferrite, the combined poles have beneficial effect on air-gap flux density by changing the ratio of the two permanent magnet materials. And the utilization of ferrite can also help lower the expense and strengthen demagnetization withstand ability. The main contents of the paper includes: introduction of basic principle of CPV-IPMSM, initiative design of CPV-IPMSM, model building, optimization and analysis of magnetic bridge parameters and pole parameters, analysis of temperature field and demagnetization.Firstly, the basic principle of CPV-IPMSM is introduced by analytical method, showing the impact of combined pole on air-gap flux density by changing the ratio of the two permanent magnet materials. According to the main specifications, the initial design scheme and the finite model are established.Secondly, the influence of magnetic bridge parameters and pole parameters on CPVIPMSM performance is investigated. After bridge parameters are optimized, the function between the pole parameters and the CPV-IPMSM performance is built by response surface method. Based on the optimization objectives, target function and constraints are built, followed by global optimization of pole parameters. Then the performance of the optimized CPV-IPMSM is compared with conventional IPMSM.Thirdly, temperature filed model is built and correlated thermal parameters about CPV-IPMSM are determined. After verification and analysis of the temperature fields in CPV-IPMSM under basic speed and top speed, the thermal circuit model and the function between temperature and pole parameters are established.Finally, the demagnetization withstand ability of CPV-IPMSM under basic speed and top speed is verified and demagnetization law under different operation conditions is investigated. Compared with conventional IPMSM, CPV-IPMSM is of better demagnetization withstand ability at high temperature. And the relation of pole parameters with no demagnetization risk is investigated.