Self-oscillating resonant converter for led applications at 500 Khz

In this paper, an improved design approach is proposed for the self-oscillating command circuit as a driver for resonant converters on LED applications. The improvements, built upon the classic design methodology, contemplate the influence of the MOSFET input capacitance, and make it suitable for high frequency application, where such parasitic elements lead to increased discrepancies. When operated at higher frequencies, resonant converters like the half-bridge series resonant inverter, imply reduced size and weight for the reactive elements, which combined to the simplicity and low cost of the self-oscillating command circuit, translates into a suitable high-power density application. The self-oscillating resonant converter design is based on the describing function method and the extended Nyquist stability criterion, granting the system a proper design prediction around a self-sustained frequency. Simulation and experimental results are shown, comparing the classic design methodology with the improved design approach up to 500 kHz, displaying the feasibility of the design.