The Design Of Permanent Magnet Brushless Dc Motor And The Electromagnetic Analysis

Permanent magnet brushless DC motor is a kind of high-tech products integrated the motor and the power electronics, which has many great advantages such as simple structure, reliable operation, high efficiency and flexible shapes and dimensions. It is widely used in aerospace systems, industrial automation equipment, medical equipment, transportation and household appliances. Now there are many people working on designing, controlling or using motors. Main content of this paper includes the following points:Firstly, the development history and main characteristics of the BLDC motor and its relative technologies at home and abroad are elaborated in details, and the structure of this paper is shown. Then the composing and basic operation theory of the BLDC motor are analyzed and the mathematical model and operating characteristics of the motor are got by theoretical analyzing.Secondly, the principle and characteristic of equivalent magnetic circuit method are introduced. Considering the performance requirements of the motor, magnetic circuit method is chosen to design the24V,30W BLDC motor. Using the electromagnetic FEM software, the performances and curves of the motor are obtained to prove the correction of the design. The effects on motor performances of the motor structure parameter are researched and analyzed by the electromagnetic FEM software.Thirdly, the principle and characteristic of electromagnetic field finite element analysis method are analyzed. Then the behaviors of the motor under both steady and transient state were simulated by using the software Ansoft, especially the working operation with or without load are analyzed and the curves about output torque, current, speed, field flux and voltage prove that the motor runs well. Then the definition of back EMF and inductance and their effect on motor performance are analyzed.Finally, the cause of motor torque ripple is introduced and cogging torque is mainly analyzed. The effects of suppression cogging torque methods about changing the arc coefficient, changing the width of notch and increasing auxiliary notch are simulated, which prove that these methods are useful.