A novel hybrid excitation sequence for a sensorless motor

Sensorless driving has been widely used for a spindle motor in HDD and DVD devices. This paper raises a new sequence to acquire larger bemf quickly than the conventional sequences. The hybrid sequences raised by the paper will combine the two sequences i.e., three-step and six-step to excite the motor. A spindle motor applied in a 50X CD-ROM driver is taken as an example to test these sequences. The amplitude of back EMF excited by the hybrid sequences is about 32% and 8% more compared with the six-step and the three-step; furthermore, the waveform of back EMF is symmetrical enough. It proves that the announced sequences are valid.