| Permanent magnet brushless DC motors (BLDCM) have been widely used. In thetraditional control method, rotor position sensors are necessary to sense six key rotor positionsignals each electric angle cycle in order to make BLDCM running. However, installation ofposition sensor limit BLDCM use scope to a certain extent.Sensorless control means that rotorposition signal can be obtained by analyzing the information of motor voltage and current insensorless condition,which can expand of the application of BLDCM.Firstly, the paper makes a detailed analysis of the fundamental structure，operationalprinciple of BLDCM and deduces its mathematical model, and then established a simulationof BLDCM control system model in Matlab／Simulink. Through the simulation, we got afurther understanding of operational principle and performance of BLDCM.Secondly, the paper held a deep research in some key techniques of sensorless controllike the principle of Back Electromotive Force（BEMF） zero-crossing detection,phasecompensation,rotor positioning principle in theory.Base on the theoretical analysis,the paperbrought forward the lagging90commutation method.In addition, the paper analy thePulse-Width Modulation（PWM） stragegy and torque ripple when commutation,and putsforward the solution.Then, the paper carried on the hardware and software design．Hardware design includeTMS320F28015digital signal processing system, current and zero-crossing of BEMFdetection circuit，IGBT driver circuit and so on．In the software design，the main programwhich included DSP system setting，keyboard real-time communication; and TIMER1interrupt subroutine which included starting, motor forward&reverse operation, calculating ofphase compensation and commutation time and double closed loop PID（Proportion-Integration-Differentiation） realized.Finally, the experimental results show that the BLDCM start smoothly and have a widespeed range,which support that the sensorless control strategy put forward in the paper has agood control performance. |
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