Three-Phase Unfolding Based Quasi-Single Stage AC-DC Converter Topologies for Battery Charging Application-Slides

Abstract: This webinar presents an innovative quasi-single stage AC-DC power conversion approach for high-power electrical-vehicle battery charging applications. The objective is to work towards reducing the cost and volume of power converters required for EV charging systems. The proposed topology fundamentally can achieve higher efficiency and power density than the conventional two-stage based converters. The front-end rectifier stage is line-frequency (50-60 Hz) switched topology allowing the use of high-power silicon IGBTs. The isolation stage can be realized by high-frequency (greater than 100 kHz) soft-switching DC-DC topologies based on Wide-bandgap devices. The two stages have coordinated control achieving active power-factor correction eliminating the need for line-frequency filters. Hence, this allows for a cost-effective, efficient, and power-dense solution.

During the webinar, a brief literature review of state-of-the-art AC to DC converter topologies will be presented. The idea of the Three-phase Unfolding approach will be introduced, followed by the quantitative benefits of this approach. Two novel converter topologies that implement the Unfolding approach will be discussed in detail. Switching modulation schemes and closed-loop control implementation will be discussed for both the topologies.

Two use case scenarios will be highlighted where these Unfolding AC-DC topologies are used. First, is a 350-kW battery charger for an electric bus. The second is a 560-kW medium-voltage 4.16 kV AC to 800 V DC front-end PFC converter for a wireless charger for electric trucks. Experimental prototypes of the power converter building blocks for each of the above two applications will be presented