Patent attributes
A high-frequency power supply apparatus for supplying high-frequency power to a load the impedance of which greatly fluctuates is provided, wherein a stable high-frequency current is always maintained without having overcurrent or overvoltage generated in a drive circuit thereof. In the high-frequency power supply apparatus, a constant-current conversion circuit is connected between an LCR series resonant circuit and a half-bridge drive circuit, high-frequency current of the LCR series resonant circuit is controlled by the voltage of the half-bridge drive circuit, and a constant-current function is applied to impedance variation of the load. Due to the constant-current conversion circuit, the gate of a MOSFET of the half-bridge drive circuit is driven with a parallel capacitor using a transformer inserted in the LCR series resonant circuit, and the phases of the high-frequency current of the LCR series resonant circuit and the output of the half-bridge drive circuit are maintained to be constant.
