Research on the Oscillation Reduction Control During Mode Transition in Hybrid Electric Vehicles

Abstract

<div class="section abstract"><div class="htmlview paragraph">In order to realize the series-parallel switching control of hybrid electric vehicle (HEV) with dual-motor hybrid configuration, a method of unpowered interrupt switching based on the coordinated control of three power sources was proposed by analyzing the series-parallel driving mode of the dual-motor hybrid configuration. The series to parallel switching process is divided into three stages: speed regulation stage, clutch combination and power source switching. The distribution control of speed regulating torque is carried out in the speed regulating stage. The speed adjustment torque is preferentially allocated to the power source of the input shaft (engine and P1) to carry out the lifting torque. Due to the high speed adjustment accuracy and fast response of the P1 motor, the input shaft is preferentially allocated to P1 for speed adjustment, that is, the torque intervention of P1. If the speed control torque exceeds the intervention capacity of P1, then it is allocated to the engine for speed regulation. In the clutch combination stage, by identifying the motor speed change in the oil filling stage and the shifting stage, the current mode switching under test and the oil filling effect of the shifting clutch are evaluated, and the current mode switching under test and the KP point state of the shifting clutch are judged. Due to the differences in different transmission processing and assembly processes, as well as the wear of the clutch in the whole life cycle; The friction coefficient of the clutch is not a fixed value, so it is necessary to develop the automatic adjustment function for the friction coefficient of the clutch. The friction coefficient of clutch reflects the relationship between clutch torque and pressure, and plays an important role in controlling clutch torque precision. The switching process from parallel mode to series mode is divided into three stages: power source switching, clutch opening and engine operating point shifting. The control method is verified by simulation analysis and real vehicle test. The results show that no power interruption occurs during the whole switching process. Therefore, the control method can successfully complete the series-parallel switching control.</div></div>