Research on the Control of Cascade Multilevel Hybrid Energy Storage System Based on Voltage Source/Current Source

In the cascade hybrid energy storage system, if energy storage battery fails, an asymmetric converter based on batteries and capacitors can be formed by disconnecting the contact switch of the fault battery. A novel control method based on voltage source/current source is proposed for this asymmetric system. The battery chains can be equivalent to voltage source, and the capacitor chains can be equivalent to current source. To solve the problem of imbalance between the battery units and capacitor units, a balancing control method is applied through adding an active power voltage vector based on the hierarchical control architecture. Steady state operation area and operation region of the proposed control method are also analyzed. The correctness and validity of the method are verified by simulation.