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In order to achieve required mechanical properties of hardened elements, such as gear wheels, dual-frequency induction heating may be used. Dual-frequency allows heating only the outline of the gear, due to mixed penetration depth of the subject frequencies. This method of hardening requires the process to be very short as heat may spread by means of conduction. This study presents a 3 kW prototype inverter and its control scheme is used to generate dual-frequency output current. The overall efficiency of the inverter is 96%. An analysis of the output resonant circuit is made to find the resonant frequencies. Finally, circuit and finite element method (FEM) simulations are coupled to analyse the effect of dual-frequency current on the magnetic field, current density, and energy density on the surface of a gear wheel.

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This paper presents performance, property analysis, and experimental research of a new low-losses Hybrid Driver for DE-Series MOSFET power transistors. The new driver can operating in (30MHz, 300W) high-frequency class E inverter. The new hybrid driver design has been developed as a PCB circuit on a thermal clad technology with the use of discrete low power components. In the project tested three integrated drivers IXYS Corporation and additionally two discrete drivers and one hybrid driver have been designed. Additionally, in this paper presents characteristic power input by the drivers (fig.5) for three operating states: at idle, at capacitance load 3 nF and at gate MOSFET 501N16A load. Also in this paper presents voltage waveforms (fig.6) and pictures of the thermal camera. At the end presents the measurements of parasitic parameters (inductances L DR , capacities C OUT and resistances R DR), switching and propagation times for all drivers. (The Class E Inverter (30 MHz, 300 W) with Low-Losses and Fast Switching Hybrid Driver for DE Series MOSFET Transistors).