A Hybrid Modulation Technique for Voltage Regulation in LLC Converters in the Presence of Transformer Parasitic Capacitance

This work proposes a Hybrid Pulse Frequency-Phase Shift Modulation technique to solve the problem of voltage regulation in LLC converters when the transformer has a considerable stray capacitance. The generalized analytical model based on First Harmonic Approximation considering this stray capacitance is provided for the first time and its effects on the converter behavior are explained. Simulation results are presented to describe the operating principle of the modulation technique and the experimental validation is performed on a 2.5 kW LLC converter prototype.