Research On Pulsating Torque For Brushless DC Motor In Wafer Cleaning Machine

The problem of pulsating torque in low speed limited the permanent magneticbrushless dc motor (brushless motor for short) use in some applications. This paper isto research the pulsating torque suppression of brushless motor used in WaferCleaning Machine. The maximum speed of brushless motor used in Wafer CleaningMachine is3000r/min, also can smooth start in low speed.This paper first introduced the research status and development trend ofelectromagnetic torque ripple suppression. The pulsating torque of brushless DCmotor composed of cogging torque and ripple torque. The cogging torque of brushlessDC motor was the main cause of low speed performance to bad. For the coggingtorque of brushless motor, we got the analytic expression of the cogging torque fromthe theoretical derivation. Then the influence of the cogging torque and ripple torqueof brushless DC motor were researched by three aspects including analytical analysis,FEM simulation and field circuit coupled simulation from different stator and rotorstructure including the slot/pole combination, auxiliary slot, magnetic pole, gap length,skewing slot/skewing magnet pole etc. On this basis, the optimal design of wafercleaning brushless DC motor was proposed. For ripple torque, we got the parametersof brushless DC motor from the field simulation, then the mathematical model wasestablished in Matlab/Simulink. In open loop, to compare with the FEM results, bothrelatively close. Then the influence of ripple torque was researched from EMFwaveform, Commutation process and PWM method. On the basis of optimizationdesign, a brushless DC motor was created and some field tests were made. Thecogging torque and pulsating torque were measured. The experimental result provedthe correctness of theoretical analysis and the effectiveness of the proposed drivesystem.