Implementation of a DC current sensing transformer with H-bridge MOSFET rectifier in a resonant LLC converter

This paper presents experimental implementation and tests the efficacy of a current feedback circuit for an LLC resonant convertor, working as a battery charger. The circuit is based on a current transformer and a second H-bridge which is synchronised with the first side H-bridge of the converter. The proposed solution, along with all mandatory requirements such as galvanic isolation, stability, fast response, offers intermittent synchronisation between the full bridge of the converter and the feedback circuit. The paper clarifies the application of the proposed current sense circuit as a current feedback loop, which is part of a digital control system. The implementation of the current measurement circuit is shown and proved experimentally.