Modeling of Fault-tolerant Flux-switching Permanent-magnet Machines for Predicting Magnetic and Armature Reaction Fields

The paper develops accurate analytical subdomain models for predicting the magnetic and armature reaction fields in fault-tolerant flux-switching permanent-magnet machines.The entire region is divided into five subdomains,followed by rotor slots,air-gap,stator slots,PM,and external air-gap imported to account for flux leakage.The coil turns and the remanence of magnets are adjusted by keeping the magnetic and electrical loading on the motor constant.The distance between the centers of two adjacent stator slots varies due to the introduction of faulttolerant teeth.According to the variable separation method,the general solution expression of each region can be determined by solving the partial differential systems of equations.The magnetic field distributions of subdomains are obtained by applying the continuity conditions between adjacent regions.Some analytical field expressions are represented as new forms under armature reaction field condition compared to those under no-load condition.Based on the developed analytical models,the flux density distribution and the electromagnetic performance can be calculated under no-load or armature reaction field condition separately.The finite element analysis is carried out to verify the validity of the proposed analytical model.

Analysis of armature reaction and winding inductances of permanent magnet brushless DC motor with deep slot concentrated coils

Based on the configuration of deep slot concen-trated coils,an analytical model is developed for predicting the armature reaction field produced by the 3-phase stator windings of permanent magnet brushless DC motors with concentrated coils by using the image method and the ana-lytical functions of the armature reaction and winding in-ductances are proposed accounting for the influence of sta-tor slotting.This approach is different from the method of equivalent distributed current sheet and more suitable for electric machines,which have concentrated coils and deeper slots.Under different control mode,the different analytical functions are presented.This will be helpful when further analyzing the performance of the motor.The results agree with the experiment very well.

Demagnetization Research on PMs in the Halbach Magnetized Pulsed Alternator

Demagnetization behavior of Halbach magnetized compensated pulsed alternator(CPA)is studied by using finite element method(FEM)under the different demagnetization factors in this paper.The effect of armature reaction magnetic field and thermal rise on demagnetization of PMs is analyzed.This paper investigates the effect of different demagnetization factors on magnetic field distribution,load current,and no-load phase voltage.A series of dynamic demagnetization points in Halbach array permanent magnet(PM)are evaluated to search the worst working point.Partial demagnetization risk can be represented by the worst working point,and the global demagnetization of the PM is represented by the no-load phase voltage characteristics after discharge.The research results demonstrated that the compensation shield with a certain thickness can increase the discharge current and weaken the demagnetization influence of armature reaction.The demagnetization effect of armature reaction on PMs at high temperatures will be strengthened.

Analysis of DC output voltage ripple in an electromagnetic doubly salient brushless DC generator

Considering the salient pole and high magnetic nonlinearity of the electromagnetic doubly salient(EMDS)DC generator,a 12/8 pole prototype EMDS generator is designed and calculated using a 2-D finite element method(FEM).The phenomenon is analyzed and that the phase voltage wave changes between 120°and 180°.The influence of the exciting current and armature reaction on the DC voltage ripple of the generator is discussed in detail,and the nonlinear rules are gained that DC voltage ripple changes accordingly.The theoretical analysis is verified by the simulation and experimental results.The results are helpful for the optimal design of the generator and the optimal control of exciting-winding.We conclude that the filter-capacitance of the rectifier can be designed.