Study On Drive And Control Technology For Electric Vehicle With In-Wheel Motors

The rear-wheel drive electric vehicle with in-wheel motors is taken as the study object inthis thesis. Focus on the key technologies of the electric vehicle with in-wheel motors such asthe drive and control technology of brushless DC motor used by in-wheel motors, electronicdifferential control strategies and control system communication network, the systemsimulation analysis, implementation of part system and relevant experimental study arecarried out on these technologies in this thesis.In order to study the operating characteristics and drive control principle of the brushlessDC motor, the physical model and the speed-current double-loop controller model based onfuzzy PID of the motor are established using MATLAB/Simulink tools. The simulationresults demonstrate that, the control characteristics of the system are satisfied applicationrequirements, which will be used as the theoretical foundation for implementation of themotor controller.For independent in-wheel motors drive system, the differential between drive wheels is akey issue need to be solved. According to the Acerkman-Jeantand steering model, theelectronic differential control algorithm based on speed is obtained. The differential curves ofinner and outer drive wheels under different conditions are obtained through simulation.In order to solve the problem of data communication between the electric motor vehiclecontrollers, the CAN communication protocol for the control system was formulatedreferringto the J1939standards. In the study, the CANoe software is used to establish communicationnetwork database and define the function of each node. The simulation and analysis of thecommunications network system is done. The result validates the application layer protocolspecification and node functions.On basis of theoretical analysis and simulation, the hardware solution of motor controlleris defined. According the solution, the minimum system circuit based on the MC9S12XS128microcontroller, MOSFET inverter bridge and its drive circuit and peripheral interface circuitof controller is designed. Based on brushless DC motor control method, motor controllersoftware code is designed using modular and tiered software design means.Finally, a motor control system and a vehicle control system in-the-loop simulationexperimental platform are built. The vehicle control model was constructed usingmodel-based method. The preliminary experiments based on the experimental platform for thecontrol system are taken, which verifies the validity and correctness of the control system.