| 摘要 |
<p>The present invention provides an improved current spike limiting circuit (49) for a DC brushless motor controller (21) arranged to operate in six-step mode. The controller has three electrically-controllable first switches (AU, BU, CU) arranged between a supply voltage (22) and a terminal (26, 28, 29) of a respective one of the field coils (A, B, C), and has three electrically-controllable second switches (AL, BL, CL) severally arranged between a ground (23) and the field coils. The improved circuit broadly comprises a regeneration polarity comparator (50) for sensing regenerative operation of the motor; a tachometer (58) for sensing motor speed; and an adjustable pulse generator (55) from momentarily opening a conducting one of the first switches for a predetermined time interval (tp) after a predetermined delay (td) following a point in time (ts) when one of the second switches is closed and another of the second switches is opened. The durations of such momentary opening and the length of the predetermined delay are controlled as functions of sensed regenerative operation and motor speed. Hence, excessive current spikes in the switches are prevented.</p> |
