LLC Converter with Hold-Up Time Compensation using Partial Power Process with Semi-Active Bridge Rectifier

This paper proposes an LLC converter using a semi-active bridge partial power process (P ³ ) circuit which is capable of hold-up time compensation. In nominal state, the P ³ circuit provides a small amount of the output power, reducing the power rating of the main LLC converter. During the hold-up time, the P ³ circuit provides a boosting gain with pulse width modulation (PWM). By utilizing semi-active bridge rectifier, the proposed P ³ circuit does not require additional converter, which is commonly utilized in most P ³ concepts, while providing both partial power and boosting gain. Furthermore, the proposed concept suppresses the peak of the resonant current in PWM controlled resonant converters. The prototype converter with 400-300 V input and 50 V/500 W output is built to verify the effectiveness.