LLC Resonant Converter with Hold-up Time Extension Technique for Computer Power Supply

A LLC resonant converter with hold-up time extension technique for computer power supply is proposed. Since the proposed circuit has a current boost-up capability of resonant inductor regardless of the input voltage level and the load power condition, operating near the resonant frequency, it can provide the power to the load as the input voltage drops to half of reflected output voltage to the transformer primary. This extends the hold-up time of computer power supply and improves the system power density and conversion efficiency at nominal input voltage. The experimental results with prototype are given to confirm the validity of the proposed circuit.