| 摘要 |
PURPOSE:To provide a phase control circuit for motor in which a switching element is protected against breakdown due to electromotive force induced in a motor through retriggering of the the switching element under generator motor. CONSTITUTION:A rectifying circuit 20 rectifies motor voltage and a smoothing circuit 21 smoothes the rectified voltage and the smoothed voltage is fed to a comparing circuit 22. The comparing circuit 22 compares the smoothed voltage with a reference voltage and produces an 'H' signal so long as the reference voltage is exceeded. If a start signal is turned ON during an interval when the comparing circuit 22 is producing an 'H' signal, a monostable multivibrator 23 produces an 'H' signal for a predetermined time. When both output signals from the comparing circuit 22 and the monostable multivibrator are 'H', a logic circuit 24 delivers a start inhibition signal to a control circuit section through an insulating section 25. |
