On The ISG Controller And System Control Strategy Of Hybrid Electric Vehicle

Conventional vehicles have been faced with crisis of petroleum and serious environment pollution, and the development of automobiles energy saving and environmental friendly becomes a mainstream of the world automobile industry. The pure electric vehicles are difficult to be widely used because of the limited driving range and high initial cost. The commercialization application of fuel cell vehicles will take a long period of time because the fuel cell technology has not been matured. Hybrid electric vehicle (HEV), which 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 a key technology of parallel hybrid electric vehicle. Automobiles with ISG having low fuel consumption and emission have become one of the world-famous advanced hybrid electric vehicles.In the ISG-based HEV, design of motor and its control system is one of the most important works in the design of powertrain. Control strategies are important for the ISG-based HEV to achieve best fuel economy, low emission and good power performance. This paper addressed the problem of selecting architecture and parameters of ISG motor. The motor was designed and the control algorithm was studied. The control system of ISG motor based on vector control was developed. The ISG-based HEV was modeled and simulated by ADVISOR2002. Energy management strategies for the whole system was developed and then evaluated by simulation.The different types of HEV configurations can be classified into three basic kinds: series (SHEV), parallel configurations (PHEV), or a combination of both (PSHEV). ISG-based HEV is a typical kind of PHEV. The ISG system with motor not coaxial with the engine is also called B-ISG system, as the motor is connected to the engine crankshaft by belt drive. The technology of B-ISG is always used in mild hybrid vehicles. In the ISG system where the motor is directly mounted on the engine crankshaft, the motor can have greater power and can be used in moderate and heavy hybrid vehicles. Considering both performance and cost, we select the structure that the motor is mounted on the flywheel output end of diesel engine and then connected to transmission via a clutch. In order to decrease the energy loss in the circuit and the cost of the system, the voltage of the ISG-based HEV is selected at 336 V. The high voltage of battery pack can bring many freedoms to the system design. In this article,In the ISG-based hybrid electric system, the electric machine should be able to work in states of electric drive or power generation. The motor drive system should provide an enough large starting moment, to meet the need of starting and ability of power-assisted. As well, the motor drive system should have efficiency as high as possible and also high reliability. In the hybrid electric power system, the classes of motor usually used mainly include direct current motor, the permanent magnet motor, the induction motor and the switched reluctance motor. After comparison of motors with different structures, the permanent magnet synchronous motor (PMSM) is selected as the electric machine used as the ISG motor. Then, the parameters of the ISG motor were selected with considering of both the performance and control objectives of the In the ISG-based hybrid electric vehicle.The control of ISG motor is a tough task as the motor has to rotate with the engine at the same speed. This thesis studies on vector control algorithm of ISG motor. The control system based on Motorola DSP type single chip microcomputer 568F8367 is developed. The inverter module are mainly composed of six insulated gatebipolar transistor (IGBT), and the space vector pulse width modulation is used to produced three phase alternating voltage, which directly drive the PMSM. The developed control system is tested on the ISG experiment platform, and the control algorithm is optimized using the experiment data. The experimental result proves that the performance indexes are meted.The vector control system much dependence on the parameters of PMSM, such as the rotor position, and complicated coordinate transformation is needed. They are problems to be solved. The direct torque control direct torque control of PMSM is studied. In this control method, field orientation is not achieved by feedback, so the rotor position is unneeded, while fast and reliable torque response can be produced. A simulation model of direct torque control system is developed using the Matlab/Simulingk toolbox and the control performance is studied by simulation results. After analysis of field weakening operation in direct torque control system, an algorithm of field weakening control is proposed and also studied by simulation. The main defaults concerned with the traditional direct torque control system are the large torque ripple, poor performance of low speed region, inconstant switch frequency, etc. The reason of torque ripple is studied and refinement algorithms world wide are reviewed. Finally, the Future research direction is suggested.The rationality and validity of control strategy have great influence on the performance of whole HEV system. The function of control strategy is to coordinated control different subsystems, making them work in optimal states, and rationally control the energy flow of the hybrid electric drivetrain. The design principle of control strategy is to optimize the power performance of HEV, and to achieve a high fuel economy, low emission and low cost at the same time. The development of vehicle control strategy should take in consideration the specific configuration of hybrid electric vehicle, as well as the real drive cycles and different drive patterns.The vehicle control strategy based on the logic threshold control is designed. The control strategy consists of several subroutines, such as the on/off control of the engine, the calculation of engine torque, the calculation of motor torque, etc. vehicle traveling is classified into six typical operation modes. The model of ISG-based HEV is established using the simulation tool ADVISOR 2002, and the developed control strategy is also implemented. The simulation results prove that the ISG-based HEV is better than the conventional vehicle in most performances.Finally, some problems for further research are proposed.