Research On Electromagnetic Design And Torque Ripple Reduction Of High Speed Brushless DC Motor

High-speed brushless DC motors have high power density and operational reliability,and have broad application prospects in many fields.Compared with the constant speed motor of the same power,the high speed motor is smaller in size,relatively difficult to dissipate heat,and has a large loss density,which determines its unique design different from the normal speed motor.Torque is a major indicator of motor performance.If the torque ripple is very large,it will be a threat to the stability of the motor.Therefore,studying the electromagnetic design and torque ripple suppression of high-speed brushless DC motors has great engineering practical significance.With the rapid development of Computer Aided Engineering(CAE),software-based simulation is gradually becoming an important method for modern motor design and its dirve and control system design.At present,the software ANSYS/Maxwell can realize 2D and 3D design and finite element analysis of motors.The RMxprt module uses magnetic circuit method to design motor,which can speed up the design of motors.In addition,ANSYS/Simplorer can realize the simulation of power electronic devices and control system design.Therefore,simulation by Maxwell and Simplorer realize the integrated design of motor design,drive and control system.At the same time,Simplorer provides an interface with MATLAB/Simulink,which greatly speeds up the design of the control system,and realizes the simulation by Maxwell,Simplorer and Simulink.The idea of this paper is using Maxwell,Simplorer,and Simulink to realize the high-speed brushless DC motor electromagnetic design,drive and control system design.And it works to suppress the torque ripple of the motor.The details are as follows:First,according to the unique design requirements of high-speed motors,RMxprt is used to complete the 1.2kW and 24000r/min motor design,and the motor parameter list is obtained through magnetic circuit calculation.The finite element simulation is performed in Maxwell to complete the relevant characteristics analysis of the motor in the static field and the transient field.The simulation shows that the designed motor meets the design requirements.Then,the problem of torque ripple under the control of six-step is studied,which using the Pulse Width Modulation(PWM)for speed regulation.The influence of different PWM modulation methods,PWM frequency and sampling current on electromagnetic torque were analyzed.A new PWM＿ON＿PWM modulation method is introduced to eliminate the non-conducting phase current tail.The non-commutating phase current is used as the sampling current to reduce the ripple caused by the current spike.A Maxwell and Simplorer simulation control model was set up for analysis and further verification through experiments.Finally,the vector control scheme of high speed brushless motor _di(28)0 is studied.The motor may be affected by a variety of parameters during operation,and conventional PI controllers are no longer suitable for this application.In response to this problem,a non-singular fast terminal sliding mode current controller is used instead of the conventional PI current controller,which has a fast speed response and good current and torque control effects.A Maxwell,Simplorer and Simulink simulation control model was built for simulation analysis.