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Development of HEV Engine Start-Shock Prediction Technique Combining Motor Generator System Control and Multi-Body Dynamics (MBD) Models
Abstract:
Previous reports have already described the details of engine start-shock and the mechanism of vibration mechanism in a stationary vehicle. This vibration can be reduced by optimized engine and motor generator vibration-reduction controls. A prediction method using a full-vehicle MBD model has also been developed and applied in actual vehicle development.
This paper describes the outline of a new method for the hybrid system of mechanical power split device with two motors that predicts engine start-shock when the vehicle is accelerating while the engine is stopped. It also describes the results of mechanism analysis and component contribution analysis. This method targets engine start-shock caused by driving torque demand during acceleration after vehicle take-off.
The hybrid control system is modeled by MATLAB/Simulink. A power management and motor generator control program used in actual vehicles is installed into the main part of the control system model. The voltage of the inverter and converter, and the capacity of the battery are expressed by simple mathematical models.
The motor generator torque and floor acceleration predicted using this method correlated closely with test results.
Mechanism analysis using this simulation revealed that the main factor in engine start-shock during acceleration after vehicle take-off is the longitudinal vibration mode of the suspension generated by driving torque. Contribution analysis of the suspension bushing and driveline torsional characteristics showed that increasing the hysteresis of the torsional damper and reducing the torsional stiffness of the driveshaft can reduce engine start-shock.