Investigations into series resonant inverter power control parameters for an effective metal induction surface hardening

Metal hardening depends on the material properties and the way the heat is being applied; therefore, a careful induction heating system parameter should be carefully selected, and in particular to meet the hardening requirements. In this study, a focus on a cost-effective design of the induction coil and the converter is presented. For that, a sample bar metal made of XC48 is considered. The methodology exploits an indirect procedure. It starts from the coil design according to the metal sample size, followed by a 2D finite element method for parameters and losses determination for the specified hardening depth. The power supply using resonant series converters is evaluated through electrical modelling simulation and which integrates a phase-locked loop scheme to account for load parameter variation. A comparison between the electrical and heat power is conducted to highlight the importance of the inverter control parameters leading to high efficiency and an appropriate and satisfactory hardening profile. A prototype system is built to demonstrate the effectiveness of the approach described.