ISG Torque Control And Simulation Study Based On Engine Startup Performance For Mild Hybrid Electric Vehicle

Engine startup and stop automatically is a very importance work mode to ISG mild hybrid electric velocity, which can improve fuel consumption and reduce emission. Because the traditional start motor is canceled, the engine is driven by ISG motor during vehicle startup. In order to meet with the demand that the startup time can't exceed 0.4 second during engine startup from still to required rotational speed, ISG motor must output enough torque. Engine startup performance is decided by engine dynamic run resistance torque and ISG motor output torque. More big run resistance, more great the output is needed, so the motor will be consumption more power and loss energy, which have an better required performance to electronic component. Except, in order to reduce fuel consumption, emission, motor output power and impact performance, an effective control method of ISG motor and engine is put forward under the condition startup time fit well with the demand. this study is a part of national science research of '863', based on subject investigation of ISG mild hybrid electric vehicle, an system and theory research is done about engine startup and ISG motor control, and the main research result like below (1) Based on the kinetic of engine crankshaft and connecting rod, analyzing the run resistance torque during engine startup, then simulating and computing the run resistance torque with two input parameters, such as cylinder pressure P and crankshaft angular velocityω. Simulation result fits well with experiment, so it show that the compute model for engine run resistance torque is feasible. (2) In order to meet with the performance need for HEV engine startup, the permanent magnetic synchronous motor(PMSM) is the best choice for power driver. A max torque/current control strategy is put on to output much more power, and developed the PMSM mathematic mode, then built the PMSM working model based on Matlab/simulink software. (3) A control strategy for integral ISG and engine working is put forward based on engine startup performance, and built the ISG and engine general working model based on Matlab/simulink software, a simulation result of engine cold startup and hot startup is concluded. (4) Based on hybrid electric vehicle test-rig, an experiment during ISG motor startup engine is done, and the experiment result fits well with the simulation result, so it show that the model of ISG motor and engine is feasible. (5) Some parameters have great effect on the engine startup are analysis, and gain an effect trend, which provide a theory basis for HEV engine startup. (6) An optimize goal is put up for HEV engine startup, and find out the best feasible parameter. So that an optimize result of engine startup is drawn, the result fit well with the experiment.