Abstract:In open-loop starting process of brushless DC motor(BLDCM) without position sensors, pulsations of torque and speed are large and motor cannot even start successfully. To solve those problems, space vector pulse width modulation (SVPWM) control schema of three-phase inverter employing 180° switch-on mode is analyzed and applied to BLDCM. Moreover, relationship between the composed stator magnetomotive force and current maximum phase′s magnetomotive force is derived with windings in Y connection. Hence, a new starting control method combing stator magnetomotive force regulation with SVPWM is proposed. Furthermore, calculation of the composed stator magnetomotive force is simplified. The proposed starting method is independent on saliency or initial position of rotor. It can also effectively suppress ripples of speed and torque, so its starting performance is greatly improved compared with conventional variable-frequency open-loop start. Finally, validity of the presented method is verified by simulation and experiment.