Bi-directional EV charging

Bi-directional power converters present challenges for automotive applications due to reliability, safety, and efficiency demands. To address this, the Totem-Pole PFC (TP-PFC) combined with Dual Active Bridge (DAB) topology is an effective solution. This approach utilizes soft-switching and minimal components while providing galvanic isolation and high efficiency.

The design includes half/full bridges connected to an inductor and high-frequency transformer, controlled by complementary pulse-width modulated (PWM) signals from a microcontroller. The direction of power transfer is determined by adjusting the signal phase.

Another suitable topology is the CLLC resonant converter, which supports high-frequency switching and bi-directional current flow. This design employs capacitors on both sides of full bridges for compactness.

For single-phase applications, 650 V silicon superjunction MOSFETs or 750 V SiC MOSFETs are ideal. For three-phase AC inputs and higher voltage batteries (e.g., 800 V), 1200 V SiC MOSFETs offer advantages in efficiency, weight, and compactness. For three-phase applications, parallel/stacked converters using DAB and CLLC approaches cover power classes from 3 kW to 22 kW.

The choice of topology, such as TP-DAB, CLLC, or LLC, is pivotal in meeting specific power conversion targets.