Development Of The Engine Auxiliary Control System On Hybrid Electric Vehicle Based On Electronic Throttle

The global oil crisis and air pollution add much importance on the automobile performance of energy saving and environmental protection. There are also two serious problems against the continual development of Chinese automotive industry. One is environmental pollution, the other is deficiency of the petroleum resources. Hybrid Electric Vehicle (HEV) employing two power sources-internal combustion engine (ICE) and electric motor (EM), has been accepted word-widely as one of the most promising methods to solve these two problems. In Japan, the United States and European countries, governments and automobile manufacturers have invested a lot to develope HEVS, HEV components and the key HEV technologies. Ongoing research shows that HEV is the most competitive approach to these two serious problems. For the time being, it has made pleasing achievement. The Ministry of Science and Technology of China has also set the development of HEVs and HEV components as one of the most important sub-projects in the"Tenth Five"and"863"program. JiLin University takes on the projects of"the new technology development of hybrid electric vehicle of JiLi Corporation", together with JiLi automobile co. Ltd. This paper is about the project: Development of the Engine Auxiliary Control System on Hybrid Electric Vehicle Engine based on the Electric Throttle.In this paper, we first designed the hybrid vehicle configuration, it includes four operation models: EV model, assistance model, hybrid model and energy saving model. We also designed the key function of the auxiliary system: direct start-stop through the fuel supply electromagnetic valve, control of the engine torque and operation range through the adjustment of throttle opening. To collect the parameters such as the engine speed, coolant temperature, intake temperature and the throttle position, and send to the mater controller, the CAN communication also is developed. The master sends the control command to the auxiliary system according to the vehicle and engine operation, plus with the driver's intention.For the control of the output torque, we used experiment data to build the table of the relation among torque, speed and throttle position with the method of interpolation and look-up table. Then we designed the engine torque calibration system, the calibrated the throttle position according to the different speed and load. In actual operation, the auxiliary controller received the required torque Tq_Target through CAN bus, then look for throttle according to the speed and torque, then correct the value based on the coolant and intake temperature. Also, we studied the control arithmetic for the electronic throttle and developed the FUZZY_PID controller. The error limit is set as the switch condition. When the error is large and exceeds the limit it will switch to the FUZZY_PID model. We got good control effect through experiment.In this paper, the hardware of the controlling system is also designed based on the idea of modularization. The processing circuit of input signal is designed, such as crankshaft speed sensor signal, spark switch as digital signal, coolant temperature,throttle position,air intake temperature as simulated signal; we also design the output circuit, that is the electronic throttle drive circuit based on the integrated chipset-TLE6220 and the electromagnetic valve drive circuit based on TLE6209 chipset. To realize the communication between the main and auxiliary controller, the CAN communication interface is designed with XC164 based SAE1939 protocol. Besides, for the worse working environment of gasoline engine, the anti-jamming design is applied on the hardware design.Much experiment were made after these design and development work: First, we performed the throttle off-line experiments. We find that, the time for rising and stabilization are better than the simple PID, and the overshoot and error of the steady state are also better. But there is a little lag with the Fuzzy_PID controlling. So the combination of the two control logic is perfect to overcome their shortage. Then, we made the experiment of throttle control effect. Through the result we found that, the auxiliary control system can receive the command from the master controller through the CAN bus and determinate the required throttle position, and the throttle responded fast. In the process of acceleration, the largest lag time is less than 200ms, witch is less than the engine response time. At the same while, the position error is small too, less than 1%. Through the above experiment, we said that the throttle can control the intake amount precisely, so did the torque.The torque calibration and verification experiment were also done. Through the verification result, we found that the calibration is excellent, and the largest torque error in the engine operation range is less than 5%, so it can be used on the car. Through the application on the car, we also found that: in the switch between hybrid and electric operation model. The engine can be started and stopped fast and reliably, witch said the direct start-stop effect is excellent and reach the predefined goal.From the above design and analysis, the auxiliary control system developed in this paper realized the predefined function, and can help the original ECU control the engine torque precisely.