Reconfigurable Three-Leg Interleaved Totem-Pole PFC Converter with SPDT Relay for Optimized Light Load Performance in EV Chargers

In this article, a new reconfigurable three-leg interleaved totem pole (R-TLI-TP) power factor correction (PFC) converter is presented for electric vehicle (EV) charger applications. Although interleaved designs offer benefits in traditional PFC converters, operating under light load conditions raises the proportion of ripple current in the inductors. Consequently, this causes line current distortions that compromise the power factor. As a result, maintaining low total harmonic distortion (THD) in the input current while achieving high performance in the PFC converter becomes a challenging task. To address this, the proposed converter uses a single-pole double-throw (SPDT) relay to switch between a three-leg interleaved configuration for heavier loads and a two-leg interleaved configuration for lighter loads. Furthermore, the two-leg interleaved configuration places the inductors in series, which increases the equivalent inductance per phase and reduces the magnitude of the inductor ripple current. Additionally, the proposed converter improves efficiency at light to medium loads by reducing the number of operational switches. The performance of the R-TLI-TP PFC converter is validated through MATLAB simulations under various loading conditions and experimental results from a 600 W laboratory prototype, tested with an AC 120 Vrms, 50 Hz input.