| There are two serious problems against the continual development of automotive industry at present. One is environmental pollution; the other is deficiency of petroleum resources. HEV(Hybrid Electric Vehicle) employs two power sources - ICE(Internal Combustion Engine) and EM(Electric Motor), has been accepted world-widely as one of the most promising methods to solve these two problems. Compared to the conventional vehicle, HEV could control the engine to work at high efficiency area, decrease the pollution and exhaust. The other significant advantage is that the traction motor could be used as a generator during braking process; it can recover part of the braking energy.ABS(Anti-Lock Braking) system can provide enough stability and steering-ability during braking. Meanwhile it can apply the ability of the brake system and get the shortest braking distance. ABS as s typical active safety component for HEV could help the regenerative braking system recover more braking energy by cooperating with it.Regenerative braking is an important method to increase the running distance for HEV, also it is an important part of the braking system. But the braking force of HEV with regenerative braking will not be distributed by the original braking force distribution coefficient. Then the regenerative braking control strategy must be studied and it is a major issue of this paper. When HEV tend to be locked, there need a feasible control strategy to adjust the regenerative braking torque and the air braking torque. This issue is not only another emphase of this paper, but also a creative point of the paper.The paper has analyzed the situation of the braking force for HEV, introduced the braking character, and illuminated the limiting condition of braking force distribution coefficient. Making sure that demands of stability and steering-ability during braking would be meet, the author ascertained the range of braking force distribution coefficient according to the configuration parameter of HEV. The other factor which influences the regenerative braking torque is the air braking force when the braking pad at different position. After clarified this question, the author has determined the max regenerative braking torque when the braking pad at different position. At last, depending on series of theories and the principles which the design of the regenerative braking system must be complied, a rational regenerative braking control strategy has been proposed.The other content on which the paper studied is how to accommodate the two braking control system (regenerative braking control system and ABS control system) when the wheels are being locked. Considering the lag of the motor control, the air pressure control, and the inertia of the vehicle, the paper proposed the concept of R threshold. R threshold is small than the a0 threshold, and if the deceleration exceeded the R threshold, the regenerative braking control system would reduce the regenerative braking torque bit by bit. And then if the a0 threshold be passed, the ABS control system would command the air braking system to decrease, hold or increase the air pressure. This integrated anti-lock braking control strategy would not only shorten the braking distance, keep the stability, but also ensure the vehicle speed slow down smoothly by reduce the regenerative braking torque slowly, in additional, it could recover part of braking energy properly.At last, the braking system model of HEV is built using the MATLAB/SIMULINK software. In the vehicle model, there are vehicle body model, the wheel dynamic model, the tire model. dynamic load model, the slip angle model, the road surface model, the air braking model and the regenerative braking system model. In the control system model, there are air pressure control system model and regenerative braking torque control model. Besides, the author carried out the off line simulation of some maneuvers, including the even surface maneuver, the jump maneuver, and also analyzed the simulation results, proved the rationality and the feasibility of the control logic.
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