The Development Of Fault Diagnosis System For Electric Vehicle Based On Vehicle Controller

Since the new energy vehicles were put forward as emerging industries by national policies, most car companies have developed and launched a variety of these vehicles, especially pure electric vehicles. But most vehicle controllers of the current domestic pure electric vehicles are lack of diagnosis function and safety control strategy in application layer. The pure electric vehicle has more complex electric components which compared to the traditional car, so it will be hard to look for the source of the faults without of diagnosis function, and it's also hard to guarantee the safety of the passengers without safety control strategy because of the complex structure and high voltage of it. So this paper developed a fault self-diagnosis system of the vehicle controller of pure electric vehicle, which is based on CAN communication bus, to improve the function and the safety of the electric vehicle.The drive motor system is the only power source of the pure electric vehicle, and the performances of it have a great impact on the electric vehicle, so it's necessary to monitor it's fault; As one of the most important input signals of the power system, the security of the accelerator throttle pedal is very important to the whole power system, so the safety control strategy of the electronic accelerator pedal is also discussed in this paper. This paper main research results are as the follows:(1) Studied the electric vehicle control strategy, analysed input and output signals of the vehicle controller, including the signals sent and received through the CAN bus, summarized the common faults and the diagnosis methods of them, made the fault dealing manners based on the control strategy. Paper also proposed a safety deal strategy of the electronic accelerator pedal, and the result of the simulation indicated that the method could correctly judge the driver's operate intention and diagnose the fault, and it could make an effective and safe output.(2) By studying the structure of permanent magnet synchronous motor drive system of pure electric vehicle, Paper analysed the parameters like speed, torque and the voltage and current under the fault condition of the motor stator interphase short, then put forward an approach of fault detection and diagnosis of motor using Fuzzy Logic, and the result of the simulation showed that the approach was effective and robust. Analysed the Negative Sequence Current of the stator winding which is under fault condition, and put forward a improved approach of fault diagnosis of the motor stator interphase short, the result of the simulation showed that the manner was sensitive to the light fault of stator winding fault.(3) Studied the international general faults coding standards, then made common faults encoding rules of the pure electric vehicles; Studied the diagnosis service standards which arebased on CAN bus, then made the protocol of diagnostic communication which including eight services. Written the control strategy of the diagnosis system software in vehicle controller, and downloaded the executable code of the diagnosis strategy and made a verification, the result showed that the sofeware was reliable.