Research On Design Of Permanent Magnet Assist Synchronous Reluctance Motor And Suppression Of Torque Ripple

Permanent magnet assist synchronous reluctance motor(PmaSynRm)is a novel machine with high reluctance torque and low rare-earth material consumption.The machine has advantages of low cost,high power density and rotor low heat generation.At present,rare-earth material rises in prices consistently and reduce supplement,high performance electrical machine with characteristics of low rare-earth material consumption have a prospective market and widely application in the future.Therefore,this essay investigate on design method of PmaSynRm and performance improvement by variable-flux design theory.The high torque ripple is the most evidence shortcoming of PmaSynRm,but the rotor design parameters is complex,which leads to torque ripple prediction in primary design is difficult.However,FEM method can predicts torque ripple precisely,but it is time consuming and geometry modelling and revise also takes a lot of burden.so this paper study on the analytical torque ripple calculation method suitable for primary design stage.The comprehensive contents are presented as follow:Firstly,influence of stator split ratio,slot poles combination and armature winding form on average torque,torque and power factor was analyzed.Then,based on “U” type rotor barrier design for synchronous reluctance motor,the amount of permanent magnet(PM)flux linkage impacts on motor mechanical characteristic was analyzed,the optimal flux linkage has conflicts in torque improvement in flux-weaken operation region and constant torque operation region.Based on above theory the design of PmaSynRm was finished and the correctness of this design method was proved by performance calculation.The final design was treated as base model.Then,based on base model,variable flux design method of PmaSynRm was investigated and analysis influence of this design method on performance of PmaSynRm.The overload capability,flux regulate region,selection of low coercive PM and amount ratio of high coercive PM and low coercive PM in hybrid series magnetic circuit structure was analyzed to find rotor design method of variable flux PmaSynRm.Rotor design method for variable flux PmaSynRm was developed based on aforementioned base model stator design.Then,a variable flux PmaSynRm prototype machine design was finished according to this method.Efficiency,torque,torque verse speed curve and is variation under different voltage of variable flux PmaSynRm was evaluated,from analysis result the application condition of variable flux design was discussed;on the view of torque and efficiency improvement,the requirement of flux variable region and maximum PM flux linkage in variable flux design was analyzed.Finally,the investigation on solving difficult of torque ripple prediction at primary design stage caused by complex rotor design parameters was done.The paper adopt MATLAB/Simulink to solve nonlinear reluctance networks of PmaSynRm to calculated rotor and stator magnetic motive force,then magnetic motive force drop in air gap was obtained.The air gap permeance function was used to take stator slot open effects into consideration and flux density in air gap was calculated.The torque ripple was calculated by integrating Lorentz's force density along air gap surface.The result shows that the analytical result of air gap flux density under rated load and no load coherence with Finite element analysis,and predicts the torque ripple of PmaSynRm under rated load and lightening flux weaken operation.