Modelling and Simulation of Fuel Cell/ Supercapacitor Passive Hybrid Vehicle System

The concept of the passive hybrid system is to develop a single-stage power conversion topology in which fuel cell and supercapacitor can be directly coupled, leading to low cost and compactness in the absence of DC/DC converters. The paper deals with the modelling and simulation of such a vehicle system. The powertrain component losses are modelled with a high level of detail, and they are functions of speed, torque and DC-link voltage. Different drive cycles divided into a low, middle, and high-speed category are used to evaluate the performance of the powertrain system. The wheel energy per distance and powertrain efficiency differs between the drive cycles due to the different speed and acceleration levels. Furthermore, the acceleration and WLTC characteristics of the powertrain system show that in the passive hybrid system, the supercapacitors can support fuel cells as a low-pass filter. As a result, the peak power requirement can be successfully achieved due to the lowered system impedance, and the fuel cell only needs to supply the average power during operation.