| 摘要 |
PURPOSE:To eliminate the application of an overvoltage to a reverse conversion thyristor by immediately detecting the zero value of a current when the current is interrupted due to the abrupt decrease in a load during the operation of an inverter, and interrupting the gate pulse of a forward conversion thyristor. CONSTITUTION:When an operation command is inputted a flip-flop 11 is set, a relay X is energized, its contact Xa is closed, and a gate input is supplied to the thyristor of a forward converter 1. When a load abruptly decreases during the operation of an inverter and the current becomes interrupted state, the zero of the current is detected by a comparator 13, and a flip-flopw 14 is set. Thus, an AND gate 16 output a stop signal. Simultaneously, the flip-flop 11 is reset, and the relay X is deenergized. When the contact Xa of the relay X is opened, the gate circuit of the thyristor of the converter 1 is interrupted. |
