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In low-temperature environment, heat supply requires considerable energy, which significantly increases energy consumption and shortens the mileage of electric vehicle. In the fuel cell vehicles, waste heat generated by the fuel cell system can supply heat for vehicle. In this paper, a thermal management system is designed for a the fuel cell interurban bus. Thermal management strategy aiming at temperature regulation for the fuel cell stack and the passenger compartment and minimal energy consumption is proposed. System model is developed and simulated based on AMESim and Matlab/Simulink co-simulation. Simulation results show that the fuel cell system can provide about 78 % energy of maximum heat requirement in -20 °C ambient temperature environment.

This paper studies a control algorithm for fuel cell/battery city buses. The output power of the fuel cell is controlled by a D.C. converter, and the output ports of the converter and the battery are connected in parallel to supply power for the electric motor. One way to prolong service life is to have the fuel cell system to deliver a steady-state power. However, because of fluctuations in the bus voltage and uncertainness in the D.C. converter, the output power of the fuel cell system changes drastically. A closed-loop control algorithm is necessary to eliminate the errors between the output and target power of the fuel cell system. The algorithm is composed of two parts, the feed forward one and the feedback one. Influences of the bus voltage and D.C. efficiency are compensated automatically in the feedback algorithm by using a PI algorithm. The stability and robustness of the algorithm is analyzed.

A vehicle control system basing on instantaneous energy optimization and series regenerative braking strategy was successfully developed for a fuel cell hybrid bus. The control system includes a vehicle control unit and other warning and measure systems. The control algorithm contains several blocks: start/stop, motor mode switch, diagnose and energy management. The movement of vehicle is divided into two parts: A) no braking process and B) braking process. An instantaneous equivalent hydrogen consumption optimization strategy was applied in process A. And in process B the braking energy was recovered partly so that the vehicle longitudinal dynamics would not be greatly affected. As a result, the fuel economy is improved from 9.6kg/100km to 7.9kg/100km in “China typical city bus cycle”.