Zhao Zhiguo

Development of the Powertrain Control System for Four Wheel Driven Hybrid Electric Vehicle

Powertrain control system for “step I” four-wheel driven hybrid electric vehicle has been developed, in which the front wheels are driven by conversional engine through automatic transmission and the rear wheels are directively driven by in-wheel motors. Firstly, hardware of the controller is designed using XC167CI chip with TouCAN structure. The bottom-level driven software of the controller is generated and compiled through comprehensively use of tool packages such as Dave and Tasking C. Secondly, different working modes of powertrain system are subdivided, and the energy management strategy based on logic threshold value control is implemented through application of Matlab Stateflow. Finally, on-board vehicle test of the powertrain control system is carried through using test methods of hardware-in-the-loop (HIL) and Bypass. The test results illustrate the feasibility and validity of the above powertrain control system.

Vehicle speed estimation in driving casebased on distributed self-adaptive unscented Kalman filter for 4WDhybrid electric car

As for the four-wheel drive hybrid electric vehicle (4WD HEV), in order to improve the accuracy and robustness of speed estimation for electronic stability program (ESP), vehicle speed estimation based on distributed self-adaptive unscented Kalman filter (UKF) is proposed in consideration of obtained driving torque and ESP sensor signals. Firstly, powertrain and kinetic model are established according to the 4WD HEV, which includes power-train system model, seven degrees of freedom vehicle dynamics model and Burckhardt tire model. Secondly, considering the model is time-varying and strongly nonlinear, UKF algorithm is adopted to design the main/sub filter. On the one hand, self-adaptive UKF is designed for measurement noise to improve its robustness; on the other hand, main/sub filter results are fused and then the fused result is used to reset each filter, which improves the accuracy of speed estimation. Finally, off-line co-simulation of Carsim-Simulink and hardware-in-the-loop (HIL) platform for 4WD HEV are built, distributed self-adaptive UKF algorithm is tested in 8-shape route driving case and low speed double-line change driving case. The results show that the proposed speed estimation algorithm based on distributed self-adaptive UKF not only has high accuracy, but also has strong adaptability and robustness.

Optimal control in brake down-shiftingprocess for hybrid electric car equipped with dry dual clutch transmission

As for the engine auxiliary braking conditions of hybrid vehicle equipped with dry dual clutch transmission (DCT), a composite braking torque distribution strategy is proposed, and the control problem of clutch transmitted torque and ISG output torque is researched. Based on the established dynamics equation of DCT shifting process, the target braking torque is extrapolated by fuzzy recognition of driver’s intention, and the motor maximum torque limitation, engine auxiliary braking torque as well as vehicle driving resistance torque are updated at real time, ISG target output torque is calculated according to the proposed composite braking torque distribution strategy. During the shifting process, based on the model and designed disengaging principle, the clutch transmitted torque is obtained. Considering the motor response characteristics and the impact of the synchronization moment, the engine speed reference curve is designed, in view of the external disturbance and model parameter perturbation, the ISG output torque during the synchronization process is obtained by applying linear quadratic optimal tracker and model reference adaptive control. At last, a torque shift phase is designed to avoid the significant impact caused by directly shifting from the in-gear stable operation to the shifting process. The simulation results show that the proposed strategy can make full use of engine auxiliary braking torque and effectively recover the braking energy, and ISG can respond to the changes in the target braking torque, ensuring fast shift.