Unified Average Model of Switched-Passive-Network Equalizer for Performance Assessment in Long-term Simulations

Abstract

Cell inconsistency is a big challenge for electric vehicles (EV) and energy storage systems (ESS), where large number of battery cells are connected in series. For the purpose of active balancing, switched-passive-network equalizers such as switched-inductor (SI-E), switched-capacitor (SC-E), and switched-resonance (SR-E) equalizers are more promising. During the equalizer development, simulation is the first approach to design the circuit topology. However, the traditional simulation method only can assess the equalizer performance in a short operation-time due to the PC’s memory limitation. This paper proposes a unified average model of the switched-passive-network equalizers to assess the long-term performance of the equalizers. The unified average models are implemented by PSIM, and the results are compared with the waveforms by a hardware-in-the-loop (HIL) real-time simulation system. It is observed that a high similarity exists between the average simulation and the switching simulation, but the execution-speed becomes faster in the proposed method. Besides, it is also proved that energy loss during the equalization process can be assessed by the average model.