Experimental Validation of a Bidirectional Three-Level dc-dc Converter for On-Board or Off-Board EV Battery Chargers

This paper presents a bidirectional three-level (B3L) dc-dc converter for electric mobility applications, namely for EV battery chargers (structures of on-board or off-board). As shown throughout the paper, the B3L dc-dc converter is only part of the on-board or off-board chargers, and may also be framed in galvanic isolated or non-isolated electrical systems. As main differentiating factor, according to the output voltage value, it can operate with three-levels, allowing to reduce the voltage applied to each switching device. Besides, it operates with the output controlled current with a frequency that is double of the switching frequency of each device. Taking into account the advantages of the B3L dc-dc converter, a comparison with a conventional converter is established. The adopted PWM strategy is defined according to the current control technique. The experimental validation is performed using two prototypes: an on-board charger and an off-board charger. The obtained results allow verifying the claimed innovative characteristics and advantages of the B3L dc-dc converter.