The Research Of Sensorless BLDC Motor Controller

Brushless DC Motor (Brushless Direct Current Motor,BLDCM) is considered asthe most promising electronic control motor in21stcentury because of its simplestructure,high efficiency, good controllability, better speed characteristics, easymaintenance, etc. The appearance of sensorless BLDCM makes the motor structuremore simple and expands the range of applications and control advantage. In Thispaper, the research is focus on the sensorless control method of BLDCM from theoryand practice.First of all,the background and application of Brushless DC motor is introducedbriefly, this paper analyzes the working principle of the BLDCM, including motorstructure, six-step control theory and the rotor position detection method from theperspective of the motor control system,while gives the mathematical model ofbrushless DC motor and the equivalent circuit.Secondly, this paper works out the control scheme for BLDCM without positionsensor, introduces PWM modulation, the method of detecting rotor position based onBack-EMF zero-crossing detection, start-up method.Then, the simulation model based on the sensorless control scheme of BLDCMis developed by Matlab/Simulink and various functional modules and functions areintroduced. It can verify the feasibility of the control method by debugging thesimulation model, and lay the foundation for hardware platform debugging.Finally, this paper introduces the hardware design of the control system, and eachrelevant circuit design of the controller.And then, test the controller based on thespecified control method and the debugging results are analyzed. At the end, thispaper summarizes the whole project, analyzes the problems encountered in debuggingand make prospects for future work.