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 a problem of determining the efficiency of high-frequency MOSFET drivers. All drivers have been tested for efficiency in the operating frequency from 10 MHz to 30 MHz. In the project tested two integrated drivers DEIC420, IXRFD630 IXYS Corporation and additionally three discrete drivers 4xEL7104, 8xEL7457 and 8xUCC27526 have been designed. The new discrete drivers design has been developed as a PCB circuit on a thermal clad technology with the use of discrete low power components. The PCB board are made of IMS material, which consist of aluminum base (1.5 mm), the layers of ceramic insulator (100 mu m) and cooper layer (35 mu m). Additionally, in this paper presents characteristic power input by the MOSFET drivers (Fig. 3) for two operating states: at idle and at gate MOSFET DE275-501N16A load. Also in this paper presents the measurement of parasitic parameters (output, series resistances R-DR) for all drivers. At the end, this paper presents the new characteristic efficiency by the MOSFET drivers determined based on equations from (1) to (10). The new MOSFET Drivers have been verified by using the universal laboratory in Department of Power Electronics, Electrical Drives and Robotics Silesian University of Technology.

W artykule przedstawiono wyniki sprzężonej symulacji modelu obwodowego przekształtnika rezonansowego z modelem MES układu grzejnego wzbudnik-wsad dla trzech wariantów nagrzewania indukcyjnego (niską-, wysoką- i podwójną-częstotliwością). Wsad w postaci koła zębatego został przesymulowany dla trzech różnych stopów stali konstrukcyjnej (C45, 41Cr4, 42CrMo4) używanej powszechnie do produkcji tego typu elementów mechanicznych. Przekształtnik energoelektroniczny o mocy 3 kW został zamodelowany w postaci mostkowego falownika rezonansowego zasilanego z sieci 3×400 V poprzez prostownik z filtrem RC i obciążonego szeregowo-równoległym obwodem rezonansowym. W wyniku badań symulacyjnych sprzężonych modeli uzyskano rozkłady pola magnetycznego i gęstości energii na fragmencie wsadu w zależności od częstotliwości pracy układu i rodzaju stopu stali konstrukcyjnej, charakterystyki gęstości energii w płaszczyźnie poprzecznej pojedynczego zęba oraz wartości temperatury zarejestrowane na wierzchołku zęba (w połowie jego wysokości) dla trzech różnych metod hartowania i trzech typowych stopów stali konstrukcyjnej.

The article presents basic information about the induction heating of gears, which are widely used in various industries. This article presents the methodology and results of a coupled FEM simulation of a circuit model for a power electronics converter connected to an inductor-charged heating system. The induction heating of gears was performed using a high-frequency inverter with SiC MOSFET transistors. A prototype inverter was built using a full-bridge structure with a series-parallel resonant circuit. The operating frequency was 350 kHz, the output power of the inverter was 3.5 kW, and the drain efficiency was equal to 96%. Coupled simulation was performed for a charge in the form of a gear made of 42CrMo4 steel (material parameters are provided in the article) for two types of heating: with and without a magnetic field concentrator. In addition, the article presents the results of co-simulation studies in the following form: a distribution of magnetic induction in the gear, energy density in the gear, the characteristics of energy density in a single tooth on the 8 mm length and the temperature of the tooth tip for two types of induction heating.