Kota Manabe

Recent Advances in TOYOTA FCHV-adv Fuel Cell System

Toward the mass introduction start in 2015, Toyota continues efforts to overcome the remaining technical challenges for the commercialization of the TOYOTA FCHV. The cold start capability is one of the main issues among such challenges. An excess amount of water in fuel cells hinders the cold start, because the water turns into ice. On the other hand, when there is a lack of water in fuel cells, the initial FC output decreases. To resolve the issue of the cold start capability, the AC impedance measurement was employed for estimating the water content in the FC stack. Based on this, the water management system was developed, and it became possible to start up the FCHV at temperatures down to -30{degree sign}C.

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 FCHVs 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 FCHVs system control and next-generation FCHVs system.