| 摘要 |
PURPOSE:To simplify the configuration of the phase control device by providing only one phase control circuit and commonly using it by switching it for low and high speed triacs. CONSTITUTION:When a speed setting unit VR is gradually raised at its setting voltage, the output of a Schmitt trigger circuit ST is inverted to turn a transistor Tr2 on to supply a gate signal from a firing phase circuit PH to the gates of a high speed triacs TRI4-TRI6, thereby flowing a current through less windings to drive a motor PCM at high speed. At this time the low speed triacs TRI1-TRI3 are turned off. When the motor speed is decelerated lower than the synchronizing speed by the unit VR, the Schmitt trigger circuit ST is inverted to turn off the high speed triacs TRI4-TRI6, and the low speed triacs TRI1-TRI3 instead start controlling the voltage. |
