Research On Key Parameters Matching And Energy Management Of PHEV With CVT

PHEV(plug-in hybrid electric vehicle) is a new type of hybrid electric vehicle, and compared to ordinary hybrid vehicles, the capacity of battery, which can charge from outside power grid, is relatively larger. Besides, PHEV can be travelling in the pure electric mode with the high power motor. When the battery runs out, the vehicle will be traveling in the hybrid mode, and timely to charge the battery, which can effectively reduce the fuel consumption and the vehicle exhaust pollution.This paper conducts the research from two aspects: parameter matching of hybrid electric vehicle and energy management strategy development.First, through the deeply analysis of a parallel type PHEV power transmission system structure, the vehicle longitudinal dynamics equation is established, carries on the thorough analysis, vehicle longitudinal dynamics equation is established, the dynamic relation of the vehicle power source is studied in the driving condition and braking condition. Based on the above analysis, key parameters of ISG, battery and engine have been designed to match a specific prototype vehicle.Then, on the basis of designed parameters, using the method of combining theory with experiment, some models are established. For example, ISG efficiency numerical model, battery charging and discharging efficiency model, engine fuel consumption and efficiency of the numerical model and the CVT model for efficiency. The above work lays a foundation for designing the energy management strategy.Furthermore, the paper goes insight into the PHEV working modes. Through defining a variable which can be called the instantaneous equivalent input power, the energy economy objective function is established. With analyzing the power requirement for the power source of the vehicle, this paper designs an algorithm to optimize the CVT speed ratio for the goal of minimum equivalent instantaneous input power. And thus the required torque can be distributed rationally. What is more, based on the above optimized CVT ratio and the distribution of the required power, a threshold energy management strategy is proposed to control the energy flow.Lastly, a PHEV back-forward simulation model on the platform of Matlab/Simulink is established to verify the rationality of the designed matching parameters and the control strategy in the NEDC cycle. The results shows that the designed matching parameters and the control strategy for the specific PHEV can meet the initial power demand.