Coil-assisted Brushless Dc Motor The Realization And Rerformance Analysis Of Brake Control

Brushless Direct Current Motor(BLDCM)has advantages of simple structure,easy to start and stop and convenient to brake,thus it is widespread applied in the fields of aerospace and industrial automation in our country.In recent decades,we have accomplished much achievements in studying ontology design and speed regulating system of BLDCMs.However,there is little research on braking operation of BLDCMs.In this paper,the research object,Coil-Assisted Reluctance Brushless DC motor(CAR-BLDCM)is composed of two sets of pole-dependent salient structure of fixed rotor with auxiliary coils added to the central motors to provide adjustable magnetic field.In detail,this paper takes CAR-BLDCM with three-phase 9/6 structure as the controlled member and does research on the motor's braking system and its quick switching between positive and negative operation.Firstly,in line with the operation principles and characteristics of mechanical conversion,the difficulties of nonlinear modeling will be relevantly analyzed and finally the theory construction of some approaches like magnetic linkage of a quasilinear model,variation curve of phase current,and PI speed regulation will be determined.In the process of operating the brake,the approach of linearized model will be adopted.Meanwhile,in comparsion of three control methods,the pronlem of larger current during operation process,will be finally solved by the opproach of voltage chopper combined with current limiter.Besides,through theoretical analysis and research,the hardware and software relevant to speed regulation system of BLDCM will be designed.The software consist of several modes as the following: power converter main circuit,drive circuit,protective circuit,and current sampling conditioning circuit etc..The hardware include main program,timer interrupt program,interrupt catcher and relavant on-off subroutine.On the condition of operating the BLDCM,this paper mainly researches on quick forward and reverse switching between braking and operating.According to the problem of insufficient torque between the forward and reverse switching,the approach of combination of single and double braking will be adopted and then the relative judgment method will be applied.As for the inversion problem caused by automatic shutdown,this paper will adopt the approach of the combination of three-phase continuous commutation braking and single-phase braking.Ultimately,some relative analysis of variation curve about forward and backward switching and on-off operation of brake will be made basen on the experimental method of combining the hardware and software.The outcomings show that BLDCM has good braking and reverse switching ability,which well paves way for further researching on speed regulation system of the BLDCM and expand its research area.