| 摘要 |
PURPOSE:To enable the AC motor to be released by a contactor of small capacity by a method wherein an inverter circuit is immediately stop-controlled by an excitation stop detecting signal when a contactor driving circuit OFF-drives the contactor for the AC motor drive. CONSTITUTION:A gate control signal is supplied from a converter control circuit 22 to the gate of each thyristor of a converter 16, and the converter 16 converts AC currents from an AC source 12 to DC currents. The gate control signal is supplied from a converter control circuit 24 to the gate of each thyristor of an inverter 18, and DC currents from the converter 16 are converted to the AC currents for driving the AC motor 10. The release of the AC motor 10 is carried out by turning a switch 30 OFF. With the switch turned OFF, a switch 34 interlocked to the switch 30 is also turned OFF, the excitation stop detecting signal is fed from an excitation stopping signal generator 36 to the converter control circuit 22 to cause the converters 16, 18 to be stopped. |
