LLC Converter With Hold-Up Time Compensation Using Partial Power Process With Semiactive Bridge Rectifier

This article proposes an LLC converter using a semiactive bridge partial power processing (P-3) circuit capable of hold-up time compensation. In a 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 pulsewidth modulation (PWM). By utilizing a semiactive bridge rectifier, the proposed P-3 circuit does not require an 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 its effectiveness.