Research Of Electronic Differential Control System For Electric Vehicle

Multi-wheel independent driving electric vehicles simplify the traditional transmission system. Multi-wheel independent driving electric vehicles have a lot of advantages in driving force distribution and vehicle dynamics control. These advantages make the related researches become more and more popular in enterprises and universities. Recently, in the field of Multi-wheel independent driving electric vehicles control, there have been plenty of key technical researches, such as electronic differential control, yaw rate control, anti-slip regulation and so on.This thesis presents a kind of electronic differential control strategy considering the vehicle rolling movement based on "Xin Huo I", which is the rear-wheel independent driving electric vehicle. As we all know, when cornering, under the impact of the centrifugal force, the vertical load of every wheel will be redistributed. Based on this fact, some researchers have done some studies about driving force distribution. Furthermore, this thesis considers that the vehicle body mass center will move in the lateral direction when cornering. This movement will also impact the redistribution of the vertical load of every wheel. Accordingly, this thesis presents a new kind of electronic differential control strategy.First, the vehicle dynamic analysis is carried out when the electric vehicle turns. The impact of sprung mass centrifugal force, unsprung mass centrifugal force and the vehicle body mass center lateral movement on the redistribution of the wheel vertical load is taken into consideration.Second, the vehicle dynamics model is built using CarSim according to the search object "Xin Huo I". The control strategy model is built using MATLAB/Simulink. The co-simulations under different kinds of driving conditions are done to verify the control performance of the electronic differential control strategy.Then, the electronic differential control unit (EDCU) is designed based on the control chip Freescale MC9S12XEP100. The EDCU hardware development is finished using Altium Designer. In the EDCU software development period, using the code generation feature of Real-time Workshop in MATLAB/Simulink, the code work is completed efficiently in CodeWarrior V5.1.At last, the electronic differential controller is applied to "Xin Huo I". The real vehicle testing results indicate that the proposed electronic differential control strategy can control the vehicle driving stability under straight-line driving condition and achieve the designed effect of differential under turning driving condition.