Model Predictive Control for a Multiport 4L NPC DAB Converter Under Unbalanced and No-Load Conditions

Multilevel (ML) neutral-point-clamped (NPC) dual-active-bridge (DAB) topologies have emerged as a promising solution for multiport dc-dc power conversion systems. In particular, the 4L NPC DAB is a promising solution for the auxiliary power module (APM) in electric vehicles (EVs) featuring a multiple-voltage architecture in their auxiliary system (AS). By connecting three low-voltage (LV) battery modules between the 4L dc-link nodes, multiple dc ports with different operating voltages are obtained. Then, EV auxiliary loads can be grouped according to their optimum voltage ratings and supplied from three distinct-voltage dc ports. In this configuration, the main challenge is to regulate the state of charge (SoC) of the LV-battery modules. For this purpose, this paper proposes a moving-discretized-control-set model predictive control (MDCS-MPC) for a 2L–4L NPC DAB in the EV APM application. The proposed control strategy combines the adjustment of modulation angles with the use of redundant switching patterns to regulate the LV-battery modules SoC in a wide operating range, including no-load conditions in the partial-voltage dc ports. Hardware-in-the-loop experiments verify the real-time performance of the proposed control.