Zero crossing points of Back-Electromotive force (EMF) is the most mature and widely used method of the speed sensorless control of brushless DC motor (BLDCM). However, with the poor performance from standstill to low speed, it is not suitable for the position servo system. Therefore, this paper first analyzes several conventional speed sensorless control schemes in the BLDCM, then presents a novel control algorithms for the BLDCM. In the proposed method, the short pulse sensing method for the rotor position in the Start-Up process and self-synchronization with zero cross points of back-EMF are combined together. As a result, the BLDCM used in the position servo system can be easily controlled from zero to high speed, the theoretical analysis is verified by the simulation results based on Matlab, it shows that the proposed algorithms can improve the performances of position servo system compared with the conventional methods.
Sensorless Control of Four-Switch Inverter for Brushless DC Motor Drive and Its Simulation
