Power source protection method for hybrid polymer electrolyte membrane fuel cell/lithium-ion battery system

Polymer electrolyte membrane fuel cell hybridized with lithium-ion battery possesses significant advantages, including the combination of large energy carrier feature with high power density to provide a power source for large fluctuated areas such as a vehicle or a construction equipment. A hybrid system obviously requires a suitable power management means to distribute each power source optimally and ensure safe and efficient power system operation. This study investigates hybrid system power distribution and the protection of power sources, namely, PEMFC and/or LIB, to extend their lifetimes under the condition of external load variations. Power distribution with the purpose of power source protection is developed to balance the power and stabilize the DC-link voltage with the developed hybrid model. In particular, two new power splitting methods are proposed: coordinated current-voltage control and dual-voltage control. Moreover, these two control schemes are selected depending on the threshold load current. The threshold load current is decided by fuzzy logic rules to prevent power shortage in PEMFC by current control for higher load and to regulate LIB's state-of-charge for lower load. To validate the proposed power management approach, experimental tests are conducted on a hybrid PEMFC/LIB power system prototype.