| 摘要 |
PURPOSE:To smoothly switch the driving speed of an induction motor by controlling the firing angle of energizing phase angle control means with zero-crossing point of an energizing current to the motor as a reference to accurately control an energizing voltage to the motor. CONSTITUTION:The dipole side input terminal PH of an induction motor M and 3-phase AC power source E of 6-pole side input terminal PL are connected at every phases R, S, T through triacs S1, S2 to control the energization by a phase angle control system. The driving speed of the motor M is accelerated by energizing the dipole side input terminal PH, and decelerated by energizing the 6-pole side input terminal PL. A high speed side switch circuit 1 for controlling ON, OFF the high speed side triac S1, a low speed side phase angle controller 2 for controlling the energizing phase angle of the low speed side triac S2, and a zero-crossing detector 3 for detecting the zero-crossing point of the energizing current are provided to control the firing angle of the controller 2 with the detected zero-crossing point as a reference. |
