Research On Analytical Calculation Of Torque And Loss Of A New Synchronous Reluctance Motor Considering Magnetic Saturation

Although permanent magnet motors have been wildly used in industry applications due to their high efficiency.However,with the increasing shortage of rare-earth materials and the rising price of permanent magnets,the machines with less or none of rare-earth materials have received widespread attention,such as switched reluctance motors,induction motors and synchronous reluctance motors(Syn RMs).Among them,Syn RMs have been widely used due to their low cost,wide flux-weakening capability,high fault tolerant capability and acceptable torque density.However,the fatal flaw of Syn RMs is high torque ripple.Since the average torque of Syn RMs increases by making the operating point to be saturated,the torque ripple becomes worse.Hence,the reduction of torque ripple for Syn RMs is imperative.In order to reduce the torque ripple of Syn RMs,a five-phase motor design is adopted in this paper,and shifted-asymmetrical salient poles are used in this novel Syn RMs.While the torque performance has been greatly improved in the five-phase shifted asymmetrical Syn RM.In addition,the stator slotting effect,the rotor structure and the saturation effect have been considered.This paper proposed an optimal analytical method for calculating the torque and related losses in the motor structure,which proves the principle of reducing torque ripple and realizes the practical calculation of related losses.The research content of this paper are mainly the design of Syn RM,the analytical calculation torque and losses,and the processing and experiment of the prototype.The research results of this paper are summarized as follows:1.A new type of shifted-asymmetrical salient poles Syn RM is proposed.First select the required and appropriate number of phases and slot poles,and design a symmetrical Syn RM.In addition,the torque ripple can be reduced through asymmetrical and shifted a angle.At the same time,the comparison verified the feasibility of the structure.2.A torque analytical method considered the saturation suitable for the new Syn RM structure is proposed.First,calculate the stator magnetomotive force(MMF)through the winding function,and the air-gap flux density is derived from the stator MMF,which is considered the stator slotting effect and rotor salient pole structure with considering the magnetic saturation;further,through the iterative algorithm method considering the magnetic saturation,the air-gap flux density and rotor MMF considering the saturation are calculated;finally,the torque and torque ripple are calculated according to the torque formula,and verified by the finite element method.3.A loss analytical method suitable for the new Syn RM is proposed.First,calculate the stator tooth flux density and stator yoke flux density based on the air-gap flux density considering magnetic saturation;then,based on the stator tooth yoke flux density,calculate the husteresis loss,eddy current loss and additional loss through the classical loss formula,and verified by the finite element method.4.An experimental prototype of a five-phase shifted-asymmetrical salient poles Syn RM was processed,and a corresponding experimental platform was built for waveforms of the prototype were obtained,and the effectiveness of the torque and loss analytical method was verified.