| Regenerative braking (energy recovery braking) of the hybrid electric vehicle is a multi-objective dynamic process of complex systems. The hybrid electric vehicle braking energy distribution and integrated control of the best, achieving energy recovery mostly under security of vehicle braking conditions, are the key technologies and important research contents of hybrid regenerative braking.Based on the CVT(Continuous Variable Transmission) hybrid electric vehicle, aiming at gaining the maximize regenerative braking energy recovery, considering the good braking performance, the paper studied on the regenerative braking control strategy of CVT system for hybrid electric vehicle, built the theoretical model, had the system and laboratory simulation, in the end ,made a performance evaluations. The main work as follows:①In order to achieve the most braking energy recovery and to ensure the safety of vehicle braking requirements, this paper built the whole vehicle braking force distribution Control Strategy under the overall braking, in the taxiway speed braking and confined brake condition, the motor regenerative braking is prior to the engine regenerative braking and friction regenerative braking when the front-wheel can work normally. We can control the CVT ratio, then gain maximize energy recovery; in the slowdown braking condition, we adopted the proportion of braking force distribution control strategy, through control the front-wheel brake pressure to meet the vehicle braking force distribution and high-energy recovery.②According to the hybrid regenerative braking on the nickel-metal hybrid rechargeable battery performance requirements, a comprehensive temperature rise, temperature difference value, protection voltage and protection current were considered, then the initial battery charge current and acceptable charging current or power calculating method were determined and built the best fast charging control strategy of multi-stage constant current charging, and then constructed the Ni-MH battery fast charging modeling and simulation was used to verify the control strategy right.③Based on performance tests and analysis of motor and battery pack, a motor and nickel-metal hydride battery pack joint efficiency model was built, and gained the best curves of the electric / battery joint working efficiency, the CVT ratio control strategy and clamping force control strategy were built, so we can improve the regenerative braking efficiency based on those strategies.④Having a CVT hydraulic system power loss analysis, the control strategy was proposed based on power matching of electric pump supplying oil ; The whole vehicle modeling and simulation based on the CVT power matching control were carried out, and the result showed that using matching power control system can significantly reduce the system flow losses and enhance the regenerative braking system, brake energy efficiency and the comprehensive recovery rate can be improved.⑤Had a hybrid electric vehicle hydraulic braking system designed, using electro-hydraulic proportional valve for front-wheel brake pressure dynamic adjustment and achieved the pressure coordination control under the work model and the whole vehicle braking force distribution; built Hydraulic brake system simulation models using AMESIM, the motor regenerative braking and the composite brake hydraulic system performance simulation were finished, and the results showed that the design of the hydraulic braking system has good static and dynamic performance which have good application value.⑥To develop a comprehensive hydraulic brake system, this system includes front wheel brake system and rear wheel brake system, by using the high-speed on-off valve, load sensing proportional valve and the trip simulator, to achieve a different mode brake pressure coordination control based on the whole vehicle braking force distribution; had conducted pressure control test and the front-rear wheels pressure distribution tests , and those tests indicated that the system had good front-wheel pressure response characteristics and satisfied braking force distribution characteristics.⑦Developed the hybrid regenerative braking experiments system based on MT and CVT which can simulate the process of braking, and realized three models: the motor regenerative braking, composite braking and friction brake and those models conversion and control; DSPACE hardware in-the-loop simulation platform was constructed for the MT and CVT hybrid regenerative braking system performance tests and analysis to verify the hybrid regenerative braking control strategy to be accurate and effective.Theoretical and experimental researches about the CVT hybrid regenerative braking system had been studied in this paper, and the regenerative braking strategy and an integrated control were proposed which can achieve high energy recycling and safety brake, developed the CVT hybrid regenerative braking system and an integrated test Hydraulic brake system, test and analysis based on a regenerative braking comprehensive strategy were implemented, the simulation and testing verified the accuracy and effectiveness of the comprehensive control strategy, which laid the foundation for the independent intellectual property rights CVT hybrid vehicle development.
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