Development Of Motor And Vehicle Control Unit For Electric Vehicles Based On CAN-bus

Nowdays, with the energy and environmental problems that caused by traditional automotive becoming increasingly serious, many countries are seeking effective solutions actively, such as pure electric vehicles. It is Motor and vehicle control unit(MCU & VCU) based on CAN-bus that is not only the key technology of pure electric vehicle, but also the difficulty in promotion. Therefore, we must make in-depth study about MCU and VCU.By analyzing the research status of MCU and VCU, a system design for a city bus is carried out,including parameter match and control strategy design. Parameter match is calculated for power source and asynchronous motor. While control strategy is designed based on bottom, working mode and CAN network. And driving mode is divided into three types, which is consisted of the economy, normal, and power, by using fuzzy control to enhance vehicle economy and power.For studying asynchronous motor based the direct torque control(DTC) and its driving performance for vehicle, asynchronous motor model is established by the mathematical model in Simulink. Then simplified asynchronous motor- vehicle dynamics model is also established to test the driving performance of the motor model. Since vehicle dynamics model is too simplified to assess the effect of nonlinear factors in driving process, simulation platform is achieved in ADVISOR software to test the performance of vehicle by using match parameters and vehicle parameters finally.According to the system design, Freescale’s MC9S08DZ60 is selected as MCU’s microcontroller. And the functional of MCU node is completed by using software design, including system initialization, speed signal acquisition and PWM output. NXP’s LPC1768,which is based on ARM kernel, is selected as VCU’s key microcontroller. Software programing is designed on μC/OS-Ⅱ operating system platform to enhance scalability of software. Accoding to the control thought of main program, some programs and flow charts, which is consisted of CAN programing, signal acquisition and task selection, are designed. Meanwhile, by comparing the advantages and disadvantages betwwen some different filtering algorithm for speed, a limiting & sliding median filtering algorithm is proposed.The control performance of DTC designed and the feasibility motor-driven vehicle are verified by the simulation of Asynchronous motor- vehicle dynamics model. The match parameters are correct, reasonable and feasible which are verified by ADVISOR simulation tests, as well as basically meet the proposed indicators. By comparing the effect of different filtering algorithms for speed, the performance of limiting & sliding median filtering algorithm is better than other’s, whose window size is 5. The results of system phsical model tests show that the CAN network can communicate normally and software function is reliable, which has good effect. The development goals desired are basically completed.