| 摘要 |
PURPOSE:To prevent the variation to the amount of adjustment of an output current from enlarging even in the region where the output current of an inverter circuit is small. CONSTITUTION:For an inverter circuit 1, the bridge circuit is constituted by four pieces of switching elements Q1-Q4. For the switching elements Q1, Q4, Q2, and Q3 in pairs which are connected in series through a load circuit 2, the ON periods are set by an inverter control circuit 3 so that a part of the ON periods may overlap each other. The output current of the inverter circuit 1 can be adjusted by an inverter control circuit 3, and it is fed back so as to keep the output current to be constant. A voltage changeover circuit 5 selectively turns on the switch elements S1-S3, according to the output current of the inverter circuit 1, and changes over the input voltage of the inverter circuit 1 in stages so that it may maintain the variation to the amount of adjustment of a load current in small range. |
