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This paper establishes the simulation model of a city bus on the basis of the EQ6110 bus prototype and its experimental data. According to the actual urban driving cycle, the fuel economy and the traction performance of the EQ6110 city bus have been simulated, and factors such as the driving cycle, the loss of power to engine accessories, the gear-shifting strategy, the fuel shut-off strategy of the engine, etc., which influence on the bus's fuel economy, are also quantitatively analyzed. Some conclusions are drawn as follows: (1) driving cycles have a great influence on the fuel economy of a city bus;(2) under the typical urban driving cycle of the public bus in China, the engine fuel shut-off strategy can save about 1 to 1.5 percent of the fuel consumption; and (3) the optimized gear-shifting rules can save 6.7 percent of the fuel consumption. Experimental results verify that the fuel economy for the EQ6110 public bus is improved by 7.2 pecent over the actual Wuhan urban driving cycle of the current public bus in China.

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This paper first describes the control strategy used in a hybrid electric public bus and then proposes a torquebalancing control strategy. Simulations were performed using the designed control strategies, and the results were analyzed under different conditions. The torque-balancing control strategy was improved on the basis of the efficiency-first ideas of the hybrid system. Finally, experiments were performed to verify that the efficiency-first and torque-balancing control strategy (EFCS) is both feasible and reliable. The simulation results showed that, compared with a conventional public bus, the hybrid electric bus could save approximately 27.3 percent on fuel consumption using the EFCS control strategy in a public bus in China, while under the Wuhan urban driving cycle.

The paper firstly describes the structure of the EQ6110HEV hybrid propulsion system. In order to accelerate the developing process of the hybrid propulsion system, an online calibrating/programming software has been simultaneously developed, and five functions of the system are helpful to develop the hybrid propulsion control system rapidly. Secondly, the online calibration system can monitor the state information of the hybrid propulsion system all the time, and modify the parametric maps or update the control programs. Based on the software package, the hybrid propulsion control system is developed and applied to the EQ6110HEV bus. Finally, experiments verify that the online calibration system is feasible and reliable, and can save about 30 per cent of the development time for the EQ6110HEV control system in comparison with that of the standard calibration system.