| 摘要 |
PURPOSE:To prevent a 3-terminal control element from damaging by interrupting the energization of a main winding and an auxiliary winding for the prescribed period form when a motor stop signal is inputted, thereby reducing a rush current. CONSTITUTION:A calculator 20 controls switching circuits 21, 22 and switching circuits 33, 34 on the basis of a signal (ZVS) synchronized with the zero crossing point of an AC power source inputted from a ZVS measuring unit 18 and a motor stop signal, and further controls 3-terminal control elements 12, 14. After the motor stop signal is inputted, a display unit 19 is provided to interrupt the energization of a main winding 13 and an auxiliary winding 15 for the prescribed period. Then, a current of one direction is flowed to the windings 13, 15 synchronously with once per twice of the ZVS and a braking is performed. At this time, the rush currents of the both terminal control elements 12, 14 can be reduced. Thereafter, a current is flowed only in one direction only to the winding 15 synchronously with once per twice of the ZVS. |
