| 摘要 |
PURPOSE:To suppress oscillation of motor current as well as surge voltage upon occurrence of overcurrent. CONSTITUTION:Reactive current is fed upon occurrence of overcurrent. If the overcurrent occurs when switches Sa1, Sb2 are turned ON, any one of them is turned OFF. Reactive current is fed to a motor resistor R to be consumed therein through a closed circuit of point P, the motor resistor R, an inductance L, the switch Sb2, a diode Da2, and the point P when only the switch Sa1 is turned OFF whereas the reactive current is fed to the motor resistor R through a closed circuit of the point P, the motor resistor R, the inductance L, a diode Db1, the switch Sa1, and the point P when only the switch Sb2 is turned OFF. Consequently, motor current decreases slowly and oscillation thereof is suppressed. Since a reactive current is fed to the motor resistor surge voltage is not applied on the switch which is thereby protected against surge voltage. |
