High-performance control for power conversion topologies in battery charging applications

With recent advances in the battery-electric powertrain industry, the world is transforming toward electric mobility at an accelerated speed. Rapid charging systems are one of the critical enablers for the electrification of transportation. Therefore, developing high-power and highly efficient battery chargers has attracted significant attention. New power electronic converters serve as the building blocks for battery chargers and are developed every day to increase battery chargers efficiency and power density. However, employing high-performance topologies in industrial chargers leads to new control challenges. This work aims to identify and address these control challenges with low-cost solutions without significantly increasing the complexity of the charger design. In the first section of this work, the totem pole power factor correction converter is studied in detail, and unique control challenges associated with this topology are identified. Among these control challenges, the issue of a DC component in the AC mains current is identified in the totem pole structure and is addressed with a novel, low-cost control technique. This control technique eliminates the risk of asymmetrical excitation and saturation for distribution transformers in electric vehicle fleet applications. Secondly, a novel method for synchronous rectifier control in LLC resonant converter is proposed, which facilitates excellent coverage of the conduction period and is robust to the transient modes of operation, affecting industrial battery chargers. Employing this control technique significantly improves the efficiency and reliability of battery chargers. Additionally, this control technique eases the thermal management of high current battery chargers. The final section proposes a novel control technique to facilitate the bridgeless operation of a single-stage, single-phase AC-DC converter for battery charging applications. Employing the proposed control technique significantly improves the converter’s efficiency and removes a thermal hotspot in the practical design of a charger based on this topology. All the main contributions presented in this work are confirmed through experiments or computer simulation, which validates the contribution of this work toward the adoption of high-performance power conversion topologies in battery chargers.Applied Science, Faculty ofEngineering, School of (Okanagan)Graduat