A Control Method to Reduce Overshoots in High-Frequency Link Current and Voltages at Load Transients of a Dual-Active-Bridge Series-Resonant Converter

Abstract

Dual Active Bridge Series Resonant Converter (DABSRC) is well researched in the literature to find out a suitable pulse width modulation (PWM) technique that can achieve voltage regulation, zero voltage switching (ZVS), and minimum rms current in high frequency (HF) link. Although the advanced PWM techniques achieve desired performance at steady state, the HF link current and voltages suffer from huge overshoots during the load transients, which can damage the semiconductor devices and can cause the saturation of the high frequency transformer. Therefore, in this paper, a relationship is derived between the pole positions and the percentage overshoot, so that any design with the trade-off between the fast dynamics and overshoot can be done analytically. As the system involves multiple state and input variables, which are also closely coupled, a multivariable state feedback controller design is proposed to control the dynamics of all the HF link state variables simultaneously. In any DAB-based topology, the peak volt-ampere (VA) rating of the passive components can increase by 80% due to these overshoots. The proposed control successfully restricts the overshoots below 25% with a settling time of 5 ms for the output voltage. The experimental verification is carried out in a 2.25 kW hardware prototype.