Three-Phase Multilevel DC/AC Converter and Synergetic Modulation for Split Batteries

This letter introduces a three-phase multilevel converter for the integration of multiple battery submodules. The circuit comprises a synergetic modulated quasi-single stage design that includes a three-phase three-level voltage source converter operating at low switching frequency and two modular series-connected half-bridge converters operating with high switching frequency. Therein, all dc-link voltage rated devices switch at low frequency and zero voltage while sinusoidal currents are ensured without a complicated control. Furthermore, it provides a multilevel conversion and consequently smaller voltage transients enhancing power quality. In addition, the modular configuration enables flexible management of the series-connected battery submodules, eliminating the need for an extra balancer between the battery submodules. This letter provides an explanation of circuit operation and the synergistic modulation technique. Simulations and experimental results are presented to validate the feasibility of the proposed circuit.