Development of Fuel-Cell Hybrid System

Abstract

Toyota Motor Corporation started the development of fuel cell vehicle in 1992, and the company began leasing a new generation fuel cell vehicle the FCHV(Fuel Cell Hybrid Vehicle) in December 2002.The FCHV's system is designed to improve the efficiency and aims for high responsiveness when the vehicle is in a transitional state. In much the same way as most electric vehicles and the gasoline powered hybrid “Prius”, the energy the traction motor creates during braking can be used to regenerate the secondary battery. The fuel cell and traction motor inverter are connected directly, with the secondary battery connected through the DC/DC converter to the fuel cell in parallel. The efficiency of the FCHV has the ability to be approximately 3 times greater than the conventional internal combustion engine (ICE) powered vehicle.In 2003, Toyota developed the highly efficient next-generation FCHV. The system uses a lithium battery, the optimum power storage device for the characteristics of the fuel cell system, and a highly efficient half bridge converter circuit. The change to a lighter secondary battery and the reduction of converter losses make it possible to improve the fuel economy by 4% over the current Toyota FCHV.This paper describes the circumstances of fuel cell vehicle development in Toyota and the overview of Toyota FCHV's system control and next-generation FCHV's system.