Patent ID: 6992406

Claim:
A power supply for inductively heating or melting an electrically conductive material, the power supply comprising: a rectifier for converting an ac input power into a dc output power at the output of the rectifier; an inverter having an input connected to the output of the rectifier, the inverter converting the dc output power of the rectifier into an ac output current supplied to an output of the power supply, the ac output current having a frequency equal to the operating frequency of the inverter; an at least one tuning capacitor connected across the output of the rectifier and the input of the inverter; an autotransformer connected to the output of the power supply, the autotransformer having a first autotransformer output terminal and a plurality of second autotransformer output terminals, the plurality of second autotransformer output terminals comprising at least two autotransformer taps; and an at least one inductive load coil connected across the first autotransformer terminal and one of the plurality of second autotransformer terminals, the at least one inductive load coil, in combination with the connected impedance of the autotransformer, having an impedance so that it is at least approximately in resonance with the at least one tuning capacitor at the operating frequency of the inverter, whereby the electrically conductive material is inductively heated or melted by a magnetic field generated from the flow of the ac output current through the at least one inductive load coil.