Research on High Gain Isolated DC Converter with Boost Link

Resonant DC/DC converters represented by LLC are widely used in various power supply systems. But if the PFM control method is adopted when the input voltage or load range is wide, a larger frequency adjustment range will inevitably reduce the converter efficiency. For applications with low input voltage levels and wide input ranges in energy storage systems, the resonant network of the traditional resonant converter is placed on the high-voltage output side, and the voltage doubler capacitor is replaced with a resonant capacitor to form a voltage doubler resonant rectifier structure. The output gain of the converter is adjusted by changing the duty cycle of the secondary side bidirectional switch. While taking full advantage of the resonant converter, it avoids the disadvantages of a wide frequency adjustment range and improves the efficiency of the converter. On the basis of analyzing the working principle of the circuit, an experimental prototype with a power of 500W was made. The experimental waveform of the prototype verified the feasibility and superiority of the converter.