| 摘要 |
PURPOSE:To reduce the shock to be applied to a load in changing the rotation from a high speed to a low speed, by applying a single-phase power supply to a low-speed winding and then applying a three-phase power supply, thereby reducing the regenerating braking torque at the time of changing. CONSTITUTION:A three-electrode switch S1 is connected to a high-speed winding W1, and a two-electrode switch S4 is connected to the two phases of the low-speed winding W2. The remaining one phase thereof is connected to a switch S5. When the S1 is opened, the S4 is concurrently closed and the high-speed winding W1 is opened, thereby the two-phase voltage is applied to the low-speed winding W2 and the speed is decreased. Thereafter, the switch S5 is closed, and the three-phase voltage is applied to the low-speed winding W2. Since a single-phase regenerating braking torque is generated and the speed is slowly decreased, the soft braking can be performed at the time of switching without using resistors and reactors, and the constitution can be simplified. |
