| 摘要 |
PURPOSE:To prevent runaway of a DC brushless motor during lead angle speed control by lagging the lead angle by a predetermined amount upon judgement of danger and regulating the speed below a dangerous rotation. CONSTITUTION:If only one ON/OFF memory 14-1 is employed, the ON/OFF memory 14-1 is set ON by the use of synchronous pulses 35 when an AND gate 7 is producing ON signals, and an output is fed immediately from the memory 14-1 to an AND gate 13 then the output signal therefrom, i.e., an anti- runaway signal, is fed to a switch box for selecting a preventing method. If switch A is selected, for example, a relay 1 in a relay group 15 is driven and this state is held until next synchronous signal arrives then a contact 16 is switched to the under side so that the phase difference of a phase voltage being fed with a lead angle with respect to the induced electromotive force (e) is brought to '0' to decrease the speed, thus preventing runaway. |
