Study on commutation for permanent magnet brushless DC motor

The control methods of permanent magnet brushless DC (BLDC) with position sensor and without sensor both involve a serious problem of phase commutation electromagnetic process. By discussing the electromagnetic process of phase commutation for BLDC with three-phase Y-connected windings in six-state operate mode, three kinds of commutation instances of BLDC motor drives, the correcting commutation, the delaying commutation and the leading commutation, was discussed in detail in the paper. Then taking a high power BLDC for an example, phase current waveform of three kinds of commutation instances was shown through computer simulation and experiment. These simulation and experiment results justify the theoretical analysis of three sorts of commutation.