| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that since the impedance and power factor of the load of a high frequency power supply device changes in a wide range, a thyristor rectifier is required to feed a large current when the inverter output voltage is low, and thereby a thyristor rectifier of large current capacity is required.SOLUTION: An inverter control circuit is provided with means for preventing a DC current flowing through a thyristor rectifier from exceeding a preset DC current upper limit, and means for controlling the inverter with a conduction width narrower than 180 degree when the DC current exceeds the upper limit. When the power supplied to the load is constant and the load is reduced, the inverter control circuit is required to reduce the DC voltage and to increase the DC current, and thereby the DC current is provided with an upper limit and prevented from exceeding the upper limit.SELECTED DRAWING: Figure 1 |
