Coil-assisted Excitation Brushless DC Motor Optimization Design

As a new structure reluctance motor,the Coil-Assisted Excitation Brushless DC Motor(CAE-BLDCM)uses auxiliary excitation coil instead of permanent magnet material.Therefore,it has the characteristics of simple structure,low factory cost,high operational reliability,wide speed regulation range and flexible controllability.It has been applied in the fields of aero-generator,electric vehicle drive,mining machinery and servosystem.However,the shortcoming of the CAE-BLDCM in terms of large torque ripple,noise and vibration are difficult to overcome.Nowdays,most of the optimization method is about the control strategy optimization but less is about structure optimization.In this thesis,the new topological structure of the motor is taken as the research object,and the structural parameters is designed and optimized.There are mainly the following aspects:(1)By analyzing the research status of electric excitation doubly salient motor at home and abroad and comparing with CAE-BLDCM,and then analyzing the structural composition and operation principle of CAE-BLDCM,the mathematical model of CAE-BLDCM is derived.(2)The CAE-BLDCM is designed by analogy with the domestic and foreign double salient motor design methods combined with the special structure of the motor.The finite element method is used to study the static characteristics of the motor to verify the rationality of the design.Then according to the electromagnetic torque characteristics and the variation law of co-energy,the matching problem between the motor armature winding and the excitation auxiliary winding is studied.The output performance of the motor with different excitation modes is analyzed,and the ratio of the two types of winding current is determined.(3)For the CAE-BLDCM stator and rotor pole number combination,the particularity of the magnetic field distribution.Analyze the variation of the moment angle characteristics of different polar arc ranges,the air gap magnetic density,winding current and output power variation under different Stack lengths,the torque characteristics of the CAE-BLDCM under different air gaps,and analyze the sensitivity of the CAE-BLDCM structural parameters;on this basis,the CAE-BLDCM torque density was further improved and optimized,and the design results were analyzed to verify the feasibility of the designed the CAE-BLDCM...