Maximizing power transfer with ZVS/ZDS in a push–pull Class E inverter for induction heating

This paper presents the design, experimental performance evaluation, and comprehensive analysis of a proposed Class E Zero-Voltage-Switching push–pull inverter, specifically optimized to maximize power transfer from the source to the load in an induction heating application. The proposed inverter features a resonant RLC tank circuit, two identical DC inductor chokes, shunt capacitors, and two power MOSFETs driven alternately to achieve induction heating. The unique design includes the introduction of intermediate inductors in the circuit that minimize higher-order harmonics and enhances continuous current operation. The key to this innovation is ZVS operation, which minimizes switching losses and optimizes power transfer by synchronizing MOSFET switching to occur at zero voltage across the device. The inverter is designed to operate at the resonant frequency of the RLC tank circuit, generating a nearly sinusoidal voltage waveform, thus facilitating efficient power delivery to the induction load. A comprehensive mathematical model is developed to analyze the behavior of the circuit, including the determination of key parameters such as resonant frequency, dynamic resistance, and power output capability. Experimental results from a 200W prototype induction heater demonstrate that the inverter can efficiently boil 250 mL of water, achieving a system efficiency of 86%. The experimental results and findings validate the proposed inverter design and suggest that it offers a satisfactory solution for applications that require resonant power conversion.