Design And Test Of The EV Electronic Differential With Dual In-wheel Motors Drive

Automobile industry has promoting the development of human society, and at the same time it led to a series of issues such as environmental pollution and energy shortages. These issues loom large, forcing governments, major auto companies as well as many research institutions to commit to promoting the development of electric vehicles(EVs) with good environmental protection and energy saving. Multi-wheel independent drive EVs have already become current popular research, each wheel of which is independently controllable. Differential control is one of the key technologies of multi-wheel independent drive EVs need to solve. This paper, focusing on practical, aims to solve differential steering problems of the test vehicle "IE-CAR", which expounds the process of Experimental determination of differential relationship, DTC Modeling and Simulation of BLDC motor, comparative analysis of two differential systems consisting of two different motor control method, design and manufacture of BLDC motor driver. This paper provides a differential control system which is simple and practical, fast dynamic response and good robustness for the EV. The main research contents are as follows:(1) Experimental determination of differential relationship. Through the analysis of the conventional Ackermann-Jeantand steering model, we found the ratio of two rear wheel speed to front wheel speed just depends on vehicle structure parameters rather than vehicle state variables such as vehicle speed. Considered with the inaccurate measurement of vehicle structure parameters and other factors, the differential relationship among four wheels is determined by pushing and steering tests of the motor is not charged.(2) Research and analysis of BLDC motor control methods. By comparing the performance of motor control of the traditional three-phase six-step control, FOC and DTC, we found that the DTC system best meets the requirements of fast dynamic response, strong anti- disturbance which the EV needs. Simulation results of two differential systems consisting of two different motor control method respectively shown that the differential system consisting of DTC better meets differential requirements of a large load fluctuation.(3) Experimental research and analysis of the differential system. This paper designed and manufactured BLDC motor driver and built vehicle CAN communication network between vehicle controller and motor drivers. In the end, the differential control system which this paper designed was experimented on the "IE-CAR" differential system test platform which this paper built. The test results show that the electronic differential this paper designed is reasonable and effective, which is able to meet the requirements of differential steering of the test vehicle.