A novel control strategy of bidirectional DC-DC Converter for interfacing ultracapacitor to fuel cell electric vehicles system based on dynamic evolution control

Abstract

Fuel cell electric vehicles gives far more promising performance. They have higher efficiency and lower emissions compared with the internal combustion engine vehicles. The fuel cell has a high energy storage capability, thus enhancing the range of operation for automobile and is a cleaner source of energy. However, the fuel cell has a slow dynamic response, so an auxiliary power source is needed during start up and transient conditions. Ultracapacitor usually used as secondary power source for improving the performance and efficiency of the overall system. Several methods have been devised to connect ultracapacitor to the fuel cell system. If the ultracapacitor is connected in parallel directly with the dc bus, its charge and discharge current cannot be controlled. Once the load changes significantly, the rush current would destroy the ultracapacitor. Therefore, a bidirectional converter needs to be inserted between the dc bus and the ultracapacitor to control the charge and discharge current. This paper proposes a novel control strategy of bidirectional dc-dc converter for interfacing ultracapacitor energy storage to fuel cell electric vehicles system. The controller of bidirectional dc-dc converter system was designed and implemented based on dynamic evolution control. Performance of the proposed dynamic evolution control is tested through simulation and experiment.