Battery Isolation Mechanism for Buck-Boost Battery Power Modules in Series

Batteries in battery power modules (BPMs) are independently controlled and thus can be isolated from the battery power source without interrupting the system operation when they have been damaged, exhausted, or fully charged. At the transient of isolating, however, resonances may occur among the inductor and capacitor, leading to high voltage and current stresses on the circuit components and spikes on the output voltage. Based on the analysis on the resonant transient, an isolation mechanism is implemented on the control program to alleviate the problem. Experiments are carried out by the laboratory battery power system with four serial bi-directional buck-boost BPMs to verify the proposed isolation mechanism.