Research On Electric Drive System Failure Control Of Four In-wheel Driven Electric Vehicle

Within many technical routes of electric vehicle research and development, thefour in-wheel driven electric vehicle (EV) is gradually showing superior quality.Compared with the general electric vehicles, it has obvious advantages in the vehicledynamics control as well as the driving force optimized allocation. It is an importantdevelopment direction of future vehicle technologies. The electric drive system failurecontrol is a key technology of this kind of vehicle, which is studied in this thesis. Themain research work includes:1. Studied the influence on vehicle’s kinematic characteristics in electric drivesystem failure situations. All failure situations have been divided into two categories:speed-maintaining-type, and speed-decelerating-type. The vehicle kinematiccharacteristic changes in the case of various failures are analyzed from the point view ofvehicle kinematics. Furthermore, a failure vehicle model has been built in veDYNAsoftware and the vehicle kinematic parameters are deeply analyzed.2. Designed a failure control algorithm in the speed-maintaining-type failuresituations. Hierarchical control structure has been utilized. In the upper layer, the drivetorque formulating algorithm is realized through proportional coefficient resetting, theyaw moment formulating algorithm is realized through fuzzy rules. In the lower layer,considering the various failure situations, a algorithm of torque distribution is proposedto meet requirement of upper layer’s putout torque value.3. Designed a failure control algorithm in the speed-decelerating-type failuresituations. An all-wheel set to zero algorithm is proposed for straight maneuver, and arule-based driving torque control algorithm is proposed for steering maneuver.4. Studied the influence on vehicle’s reliability with the electric drive systemfailure control. Four in-wheel driven EV’s reliability model has been built based onStochastic Petri Nets (SPN), and the simulation results proved that the failure controlcan improve the reliability of the vehicle systems.To validate the effectiveness of the proposed failure control algorithm in this thesis, a simulation model is designed within the veDYNA and Simulink software. All kinds ofdrive system failure situations are simulated. Simulation results show that the failurecontrol algorithm can keep driving ability and vehicle stability when driving andimprove speed decelerating performance and vehicle stable state when parking underthe condition of electric drive system failure.