TRAVELLING WAVE INDUCTION HEATERS WITH COMPENSATING WINDINGS

A major cause of the relatively low power transfer to the load on an induction heater, of either the pulsating or travelling field type, is the low magnetising reactance due to the large effective airgap when compared with a conventional transformer or induction motor. Although the power factor of an induction heater can be improved by capacitors connected in parallel with the induction coil, this does not lead to any improvement in the performance of the heater. This paper discusses how the power transfer to the load can be improved by using a compensating winding connected to capacitors, to improve the performance of the heater. The technique leads to an increased airgap voltage, resulting in both a greater power transfer to the load and an improved input power factor.