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In this paper, in order to avoid the frequent switching of engine operating points and improve the fuel economy during driving, this paper proposes a control strategy for the 4-wheel drive (4WD) hybrid vehicle based on wavelet transform. First of all, the system configuration and the original control strategy of the 4WD hybrid vehicle were introduced and analyzed, which summarized the shortcomings of this control strategy. Then, based on the analyze of the original control strategy, the wavelet transform was used to overcome its weaknesses. By taking advantage over the superiority of the wavelet transform method in multi signal disposition, the demand power of vehicle was decomposed into the stable drive power and the instantaneous response power, which were distributed to engine and electric motor respectively. This process was carried out under different driving modes.

A practical configuration of the power train for the parallel hybrid electric vehicle (HEV) is presented in this paper. The parameters of the power unit (included engine, motor, battery) that must be considered and determined during parallel HEV designing are calculated and discussed in details according to the vehicle requirements for maximum speed, acceleration time, maximum grade ability, emission, fuel efficiency. The parameters of the battery are determined by calculation and the measures that will be taken in design are also discussed in this paper. In cycles it must be insured that the consumed energy and absorbed energy through regenerative braking are balance. Thus the battery pack will never have to recharge from wall plug, the range is as long as conventional vehicle. The ratio of torque-combination device, transmission and the final drive gear is optimized and determined respectively based on the vehicle criteria of traction performance and the fuel economy.

Developed control algorithm of series power train for fuel cell transit bus is presented systematically, which keeps fuel cell pack's operation points on the locus of highest efficiency. The off-line simulation model of series power train for fuel cell transit bus is developed which includes sub-models of control system and controlled objective (such as fuel cell pack, motor, battery pack and so on). The debug and validation of control algorithm is performed on developed modular test facility. The results show that developed control algorithm can effectively keep fuel cell pack's operating on the locus of high efficiency points and much more fuel economy can be achieved than that of conventional ICE power train, meanwhile battery SOC can be maintained within reasonable level without charging outside during cycles.

During the vehicle braking, the Regenerative braking system (RBS) transforms the kinetic energy into electric power, storing it in the power sources. To secure the baking process, it is required to use hydraulic braking pressure to coordinately compensate the regenerative braking pressure. The traditional hydraulic pressure control algorithm which is used in regenerative braking system coordinated control has obvious laddering effect in braking. Unit control cycle pressure deviations seriously affect the comfort and the braking feeling on the vehicle.

Utilizing the developed off-line simulation model of series power train for fuel cell transit bus, the study on the influence of components' parameters on acceleration performance and fuel economy of transit bus is completed. Based on these the guideline strategies of parametric design of series power train for fuel cell transit bus are brought forward in this paper. Given the condition of propulsion requirement the parametric design for this transit bus is performed targeting minimizing fuel consumption. It is conclusion that the appropriate components' parameters determined by means of parametric design can make fuel cell transit bus achieve much better acceleration performance and much lower fuel equivalent consumption than that of baseline transit bus.

Utilizing the developed off-line simulation model of series hybrid power train the study on the influence of components' parameters on acceleration performance and fuel economy of transit bus is completed. Based on these the guideline strategies of parametric design of series hybrid power train for transit bus are brought forward in this paper. Given the condition of propulsion requirement the parametric design for this transit bus are performed targeting minimizing fuel consumption. It is conclusion that the appropriate components' parameters determined by means of parametric design can make series hybrid transit bus achieve much better acceleration performance and much lower fuel equivalent consumption than that of baseline transit bus.

In concept design and prototype development of parallel hybrid power train for transit bus one of the main concerns is to determine the appropriate parameters of power train components. Utilizing the developed off-line simulation model of parallel hybrid power train the study on the influence of components' parameters on acceleration performance and fuel economy of transit bus is completed. Based on these the guideline strategies of parametric design of parallel hybrid power train for transit bus are brought forward in this paper. Given the condition of propulsion requirement the parametric design for this transit bus are performed targeting minimizing fuel consumption. It is conclusion that the appropriate components' parameters determined by means of parametric design can make parallel hybrid transit bus achieve much better acceleration performance and much lower fuel equivalent consumption than that of baseline transit bus.

In concept design and prototype development of hybrid power train with ISG (Integration of Starter and Generator) for transit bus one of the main concerns is to determine the appropriate parameters of power train components. Utilizing the developed off-line simulation model of hybrid power train with ISG the study on the influence of components' parameters on acceleration performance and fuel economy of transit bus is completed. Based on these the guideline strategies of parametric design of parallel hybrid power train for transit bus are brought forward in this paper. Given the condition of propulsion requirement the parametric design for this transit bus is performed targeting minimizing fuel consumption. It is conclusion that the appropriate components' parameters determined by means of parametric design can make hybrid transit bus with ISG achieve much better acceleration performance and much lower fuel equivalent consumption than that of baseline transit bus.

A new control strategy for parallel hybrid electric vehicle with ISG is presented in this paper, in which engine operation points are limited within higher efficiency area by the control strategy and the state of charge (SOC) is limited in a range in order to enhance the batteries' charging and discharging efficiency. The control strategy aims to reduce total energy consumption at each instantaneous time interval by dynamically adjusting the amount of power supplied by the engine and the pack of the batteries. The off-line simulation model of the parallel HEV power train is developed which includes the control system and controlled objective (such as engine, electric motor, battery pack and so on). The results show that the control stragegy can effectively limit engine and battery operation points and much more fuel economy can be achieved than that of conventional one.

The new control algorithm for parallel hybrid electric vehicle is presented systematically, in which engine operation points are limited within higher efficient area by the control algorithm and the state of charge (SOC) is limited in a range in order to enhance the batteries' charging and discharging efficiency. In order to determine the ideal operating point of the vehicle's engine, the control strategy uses a lookup table to determine the torque output of the engine. The off-line simulation model of parallel HEV power train is developed which includes the control system and controlled objective (such as engine, electric motor, battery pack and so on). The results show that the control algorithm can effectively limite engine and battery operation points and much more fuel economy can be achieved than that of conventional one.

Logic threshold control algorithm for parallel hybrid electric power train is presented systematically, in which engine operation points are limited within higher efficient area by logic threshold control algorithm targeting fuel economy. The off-line simulation model of parallel HEV power train is developed which includes sub-models of logic threshold control system and controlled objective (such as engine, electric motor, battery pack and so on). The debug and validation of logic threshold control algorithm is completed on developed modular test facility. The results show that the simple and practical logic threshold control algorithm can effectively limited engine operation points and much more fuel economy can be achieved than that of conventional ICE power train.

Developed control algorithm for series hybrid electric power train is presented systematically, which keeps engine operation points on the locus of highest efficiency torque/speed points using a lookup table defined by engine power and speed. The off-line simulation model of series hybrid power train is developed which includes sub-models of control system and controlled objective (such as engine, motor, battery pack and so on). The debug and validation of control algorithm is performed on developed modular test facility. The results show that developed control algorithm can effectively keep engine operating on the locus of high efficiency points and much more fuel economy can be achieved than that of conventional ICE power train, meanwhile battery SOC can be maintained within reasonable level without charging outside during cycles.