Study On Modeling And Control Algorithm Of ISG Systems For Hybrid Electric Vehicle

Automobile has caused serious environment pollution and crisis of petroleum. The development of electric vehicle is suffocated due to limited vehicle-used battery capacity. Hybrid electric vehicle (HEV) that combines the advantages of the conventional automobile and electric vehicle arises and becomes one of the most feasible ways to solve pollution and fuel problems. Integrated starter/generator (ISG) is one of the world-famous advanced technologies for future car, which satisfies the requirements of high efficiency and low exhaust nowadays and in future. This thesis mainly studies on modeling and control algorithm of ISG systems for hybrid electric vehicle. On the basis of current advanced theories and models of HEV, this article addresses the following contents: selection and parameters calculating for components of drivetrain, energy management strategies and control methods of key parts for the whole system, modeling and simulating of ISG-based HEV using ADVISOR2002, and corresponding estimate. In an HEV, the auxiliary power unit is combined with electric propulsion. The different types of HEV configurations can be classified into three basic kinds: series, parallel configurations, or a combination of both. To improve the output power of the batteries and compact the structure of the driving system, we adopt the means of direct start with close clutch and enable the function of start and generation for ISG. Plate-formed ISG directly fix at end of the output shaft of engine, and make the parallel hybrid driving system advanced and compact with high efficiency. At the beginning of start process, the engine is driven to some rotate speed (a little higher than the idle speed) by ISG, and then engine is ignitus. In this way, ISG acts as a starter thus reduces the exhaust during start process. In normal situation (cruise), ISG stops, and engine provides the necessary power. When speed up or upgrade, ISG acts as a motor to assist propulsion, both the ISG and the engine can apply torque to move the vehicle and their torque combines on the engine output shaft. When speed-down or brake, ISG acts as a generator, which recovers energy through regenerative braking. When the battery SOC is lower than the minimum allowable SOC, the engine will provide excess torque which will be used by the motor to charge the battery. When vehicle waits at the idle speed for long time, ISG turns off the engine through ECU, and save the fuel and reduce the exhausts. The ISG systems components include an engine, a motor and batteries. Considering the power, economy and exhaust of engine, four-stroke gasoline engine and diesel engine is the best choice. ISG should have powerful starting torque, wide tuning range, high efficiency, low waste and high reliability. Also the size and mass of ISG are limited. This system selects the permanent magnet motor after compare the characteristic of several motors. Vehicle-used battery should have considerable energy and power density, good charge and discharge efficiency and wide working range. The system selects Ni-MH battery, which is fit for irregular charge and discharge states on PHEV. We make models of components and whole vehicle in ADVISOR2002 after analyze the power necessary and match for the ISG systems. ADVISOR models the engine, the motor and battery through experimental data. The engine model is composed of the engine torque block, the engine speed estimator and fuel use and EO emission block. The battery is modeled as an equivalent circuit comprising a perfect open circuit voltage source in series with an effective internal resistance. It is made up of the pack open circuit voltage and internal resistance block, the limit power block, the compute current, the SOC algorithm and the thermal model block. We modify the motor model in ADVISOR because the permanent magnet of motor is sensitive to temperature. Here we add the temperature-sensitive blocks for speed and torque and consider the non-thermal loss. And whole vehicle model is designed based on BD_INSIGHT of the model library in ADVISOR with the models of individual components. The fuel use, exhaust and battery SOC vary with different control strategies for the same PHEV. This article introduces the electric assist control strategy, the electric assist control strategy with SOC balanced, the adaptive...