The Research On Strategy Of Fieldbus Scheduling And Vehicle Control In Distributed Control System Of EV

Along with the progress of electronic technology, automobile is developing towards the direction of multi-function and the trend of intelligence and network is becoming more and more evidential. Electric vehicle is an intricate system composed of several sub-systems and its whole performance and secure dependability all rest with the cooperative operation of all sub-systems.For fulfilling the requirements of control in electric vehicle, through the detailed analysis of the fieldbus technology in vehicle the scheme of electric vehicle in distributed control system based on CAN fieldbus is confirmed. And for the first time the scheduling algorithm based on time-triggered fixed priority in CAN fieldbus is proposed and tested.To reduce the jitter of message responsive time and effectively utilize the network physical bandwidth resources, the feasibility of applying TTCAN protocol to the EV is studied and at the mean time the mixed scheduling algorithm is proposed, in which the static scheduling is framework combined with the dynamic scheduling. In the mixed scheduling algorithm the"dual phase"basic period is brought forward, which separates the transmission of periodic message from that of the aperiodic and effectively avoids the jitter of transmission delay of periodic. For the aperiodic message, the priority promotion dynamic scheduling algorithm based on deadline is proposed, which not only guarantees the real-time of message response but also improves the utilization of bandwidth. Through the experiment, the mixed scheduling algorithm can satisfy the real-time requirement of periodic messages and avoid deadlock of aperiodic messages. What's more, it can utilize the redundancy bandwidth to transmit the aperiodic messages.To satisfy the demand of EV driving capability and after taking the operating characteristic of the motor and the driving ability of battery into account, an innovative control strategy for driving system is proposed, which preferably deals with the problems of motor overload,charge and discharge ability of the battery and the feedback of braking energy. Based on the ADVISOR software, a simulation platform for EV was designed, which processes the relative simulations on the road case, accelerating ability and the feedback of braking energy. The simulation results show that the feedback of braking energy effectively improves the energy utilization of the EV. The real platform and road environment test confirm the simulation result.