Research On Torque Coordination Controller Design Method For A Hybrid Electric Vehicle During Mode Transiton

Due to the excellent fuel economy and emission performance, hybrid electricvehicles(HEVs) are being more and more widely used. However, the fact that HEVs arepowered by multiple sources leads to a much more complex vehicle structure, whichenriches its driving modes as well as brings about mode transition issue under differentdriving conditions. It will severely impact drivability and the comfort of passengerswithout properly coordinating torques from different power sources during modetransition. In this paper, mode transition from pure electric driving to hybrid driving isstudied, and the major research is on dynamics modelling, torque coordination controlmethod as well as the controller hardware design.First, The structure of a series-parallel HEV is analyzed and the dynamics model ofaforementioned mode transition is established. Because of the clutch friction torqueintroduced in the process of clutch engagement of mode transition from electric drivemode to hybrid drive mode, the total output torque will fluctuate strongly and accelerateclutch wear. Therefore, this paper proposes the vehicle longitudinal jerk and clutchfrictional losses as two evaluation indexes for the performance of mode transition.Based on these two indexes, the simulation results of open loop control for modetransition is analyzed and disadvantages of this method is pointed out.Second, a control allocation based torque coordination control method is designedto solve the over actuated control problem. This method presents a two level controllerwhich includes a upper level pseudo instruction planning and a lower control allocation.Explicit model predictive control method is used for the pseudo instruction planning towork out the control input constraints problem and get control rates offline, avoidingrepetitive online optimization. The lower control allocation employs optimal allocationto allocate the actual control. Then, the proofs of the stability of closed loop system aregiven, and the simulation environment of the control system is built in Matlab/Simulink.The effectiveness of the designed torque coordination controller is verified and theinfluence of each parameters of the controller on control performance is analyzed.The hardware of the torque coordination controller is designed at last. This paperfocused on the design of interface circuit of controller to ensure the correctness andreliability of signal transmission. The CAN(Controller Area Network) bus interfacecircuit and the signal acquisition interface circuits are designed. Then simulation andtest of these circuits are conducted to verify the effectiveness of the circuits.Considering the bad electromagnetism environment in HEVs, several EMC (ElectroMagnetic Compatibility) tests are made to meet the standards for automotive electronics including ESD(Electrostatic Discharge) test, transient immunity test, capacitivecoupling immunity test and BCI(Bulk Current Injection) test.