Research and Application of BSG Motor Control Technology with a Start-stop System

Abstract

by developing a start-stop system of a BSG motor, this paper systematically presents the vehicle control principle, strategy and verification and assessment indicators of the start-stop system, and applies it successfully in a motor. Exhaust emissions and fuel-consumption tests of a vehicle were performed in the rotating hub, and the results show a 5% reduction in fuel consumption for the motor, and a 12% decline in fuel consumption when the experiments were carried out in urban areas. The control technology and vehicle examination and evaluation indicators have important guiding significance to the subsequent research of the start-stop system. Introduction A BSG start-stop system belongs to a micro-hybrid technology. In other words, at the engine’s idle speed, if the external environment and the vehicle status satisfy the start-stop system requirement, the engine automatically turns off when the driver releases the clutch pedal, and the engine automatically starts when the driver depresses the clutch pedal or the brake pedal[1,2]. The technology makes small changes to conventional vehicles and can significantly reduce fuel consumption, so it has become an important technology for vehicle energy conservation and emission reduction. The vehicle control unit receives the sensor signal and the signal coming from the CAN bus, and judges whether the BSG system is working and determines whether to start or stop the engine according to the internal control strategy[3], and controls engine starting and flameout. The vehicle control unit can control the starting and shutdown relay, thereby controlling the original vehicle ECU as well as controlling engine starting and flameout. When the vehicle control unit’s shutdown relay controls the high level output, the shutdown relay switches off, the ECU power cord is disconnected, and the engine stalls. The starting gear of the original vehicle ECU ignition switch is connected to the signal line[4,5,6]. When the vehicle control unit starts, the relay control terminal has low level output, and the starting relay is closed. The starting gear of the ECU ignition switch is joined, and ECU controls the engine starting. Therefore, the vehicle control unit controls engine starting and flameout by using the relay simulation key. Vehicle Control Strategy The vehicle control strategy consists of three parts: the vehicle and driver safety, driving operation habits, and the environment and road adaptability. According to the abovementioned strategiese, the vehicle formulates a start-stop system control strategy, the automatic engine stopping control strategy and the automatic engine starting control strategy. Factors taken into account for developing the vehicle control strategy Factors regarding the vehicle and driver safety: whether the seat belt is fastened, whether the engine hood is closed, whether the BSG system is faulty, engine coolant temperature, brake system pressure after the engine is switched off, automatic vehicle sliding speed after the engine is switched off, the state of charge of a battery, and catalyst temperature, etc. 4th International Conference on Mechatronics, Materials, Chemistry and Computer Engineering (ICMMCCE 2015) © 2015. The authors Published by Atlantis Press 286 Factors regarding driving operation habits: whether the seat belt is fastened, whether the transmission is in neutral, whether the clutch is disconnected, and whether the transmission is in reverse gear and so on. Factors regarding the environment and road adaptability: the ambient temperature, the air conditioner application signal and automatic engine flameout when the vehicle speed is smaller than a specific value, etc. Fig. 1 The principle diagram of the vehicle control strategy The Main Content of the Vehicle Control Strategy The Start-stop System Closing Control Strategy The start-stop system closing control strategy can be divided into subjective and objective levels: when the driver wants to close the start-stop system subjectively, he/she can close the start-stop system only by pressing the system closing button. If one of these conditions is met: the driver is not wearing a seatbelt, or engine hood is not closed, or the BSG system is faulty, the start-stop system automatically stops working, and the vehicle condition is the same as that without a start-stop system. The start-stop system closing control strategy is shown in Figure 2. Fig. 2 The block diagram of start-stop system shutdown control The Automatic Engine Stopping Control Strategy When the driver encounters traffic lights or needs long-stay parking, the start-stop system can play a role and achieve automatic engine shutdown only when all of the following conditions are met. The automatic engine stoping control strategy is shown in Figure 3. engine cutout/idling engine start engine flamout start-top system working