Discharging scenario of serial buck-boost battery power modules with fault tolerance

A battery power source is formed by bi-directional buck-boost type battery power modules (BPMs) connected in series. The total required load power is collaboratively supplied by all BPMs, which can virtually be controlled independently. Therefore, the discharging currents of the batteries in BPMs can be scheduled in accordance with the remaining state-of-charges (SOCs) to acquire charge equalization during the normal operation. In addition, fault tolerance can be included with such a configuration. Under abnormal conditions, the exhausted or unexpected damaged batteries can be isolated from the associated buck-boost converters without shutting down the system. A discharging scenario is developed and embedded in a micro-controller and implemented on a laboratory battery power system with four BPMs. Experimental tests are carried out to demonstrate the effectiveness of the fault-tolerance mechanism.