Modeling and Simulation of the Interaction Between the Battery and DC-Link Capacitors in Cascaded H-Bridge Converters

Battery electric vehicles (BEVs) are becoming increasingly popular due to the growing demand for sustainable transportation solutions. To improve the efficiency and lifetime of the battery pack in BEVs, cascaded H-bridge converters are gaining popularity in research and industry. To help in optimizing the design of these converters, the modeling of the interaction between the battery and the DC-link capacitors over a wide dynamic range (i.e., from 1ns to 100 µ s) is presented, where different equivalent circuit models of the capacitor are used to capture the non-ideal behavior of the capacitor. The models are validated using experimental measurements from a single-phase cascaded H-bridge converter. The results show that the equivalent circuit model of the DC-link capacitors is critical to accurately determine the battery current over the wide dynamic range. For applications where only fast dynamics are of interest, i.e., switching transients (1 ns), a simple RLC model is sufficient to accurately track the battery current.