Research On Rotor Eddy Current Loss Of High-Speed Permanent Magnet Synchronous Motor

The high-speed permanent magnet synchronous machines(HSPMSMs)have become a hot topic in the development of electrical machinery in recent years due to the advantages of high power density,driving high-speed load directly,excellent control performance and so on.However,due to the small size of the HSPMSMs,the rotor heat dissipation condition is poor.As the frequency of the motor increases,the rotor eddy current loss(RECL)increases sharply,and the temperature rise of the permanent magnet(PM)increases,which aggravates the risk of irreversible magnetization of the PM in HSPMSM.In order to ensure the stability of the motor,it is very important to calculate the RECL of HSPMSMs quickly and accurately.Firstly,by combining the subdomain method with the equivalent magnetic circuit method,an analytical model of the RECL for HSPMSM with a conductive sleeve is established considering stator slotting and stator core saturation.In this model,the influence of eddy current reaction is considered by establishing the diffusion equation in the active subdomain,the influence of stator grooving is considered by adopting the magnetic conductivity model,and the influence of stator core saturation is considered by building the equivalent magnetic circuit model.Based on the analytical model,the RECL of HSPMSMs with several common sleeve materials is analyzed.In order to guide the design,the influence of different sleeve thickness and conductivity on RECL is calculated respectively,which provides a reference for the design of similar motors.Secondly,the RECL analytical models of non-concentric magnetic pole(NCMP)and rotor shielding cylinder(SC)structure HSPMSM are established respectively.The eddy current loss(ECL)of concentric and NCMPs is analyzed and the reducing effect of NCMP on ECL is studied.Parameterized calculation of the eccentricity of the NCMP was carried out,and the relationship between the parameters of the NCMP with the minimum ECL of the PM was obtained by combining with the analytical formula.Next,an analytical model of RECL considering the three-dimensional distribution of eddy current is established for a HSPMSM with both conductive sleeve and SC structure.The equivalent impedance method is used to consider the end effect of eddy currents.On this basis,the applicability of the SC was analyzed.Through the influence of the conductivity and thickness of the SC on the RECL caused by each harmonic current,a parameter design method of the SC was obtained with the goal of minimizing the RECL.Finally,in order to verify the correctness of the analytical model,the loss separation experiment and C-core experiment were used to test the RECL of several PMSM.In the loss separation experiment,the motor iron loss is measured,and then the stator core loss is measured through the soft magnetic material test platform,and then the RECL is separated.The analytical results are compared with the experimental results to verify the correctness of the analytical model.For the SC structure,a C-type core loss testing platform was established,and a variety of SC materials were tested.The correctness of the multi-layer subdomain model and the reduction effect of the SC on the RECL were verified.