Industrial Technology Research Institute

Hsing-Yu Lin

Shyh-Jier Wang

Shir-Kuan Lin

Hsing-Cheng Yu

A sensorless driving method for a brushless DC motor is provided. The time for the motor to rotate an electrical angle 60&#xb0; is obtained by alternatively counting the occurrences of zero crossings with two counters and comparing the counted values, and the motor is delayed an electrical angle of 30&#xb0;, by which a precise commutating time is obtained. The driving method provides a mask-based phase shift digital detection mechanism for effectively detecting true zero-crossing points. The driving method further provides an inhabitation mechanism with the function of soft-switch for inhibiting noise caused by transistor switching. By using these two counters, the time for the motor to rotate two electrical angles 30&#xb0;&#x2212;&#x394;&#x3b8; and 30&#xb0;+&#x394;&#x3b8; are obtained and stored in two registers. The time period before and after the commutating point is added into a pulse width modulation (PWM) signal to reduce the noise and vibration.

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Taichung County, Taiwan

Hsing-Yu Lin