Development and performance analysis of a hybrid fuel cell/battery bus with an axle integrated electric motor drive system

This paper presents the results of a research project aimed at developing and evaluating the viability of fuel cell vehicles for urban public transit applications and investigating ways to commercialize them. Considering a low-floor bus design and high efficiency of powertrain, one of the salient characteristics of the proposed fuel cell/battery hybrid bus is the E-drive axle, which integrates two near-wheel permanent magnet synchronous motors (PMSMs) in the rear axle. As an important part of the vehicle's powertrain, the E-drive axle was employed to drive the vehicle, capture the breaking energy and match the required speeds of the differential. The configuration and parameters of the powertrain of the hybrid fuel cell/battery bus are given in detail. To extend the life of the fuel cell stacks, the change in the output power of fuel cell stacks is controlled to be gradual via a DC-DC converter depending on the energy management strategy, which was described in this paper. An energy analysis based on a chosen driving cycle has been conducted to study the efficiency of the proposed powertrain, which shows that the hydrogen consumption of the bus is 13.29 km/kg. Also, the road test results indicated the tractive capabilities and maneuverability of the bus can reach the design specifications.