Research on the Anti-Shuffle Control for Hybrid Electric Vehicles in the Parallel Mode

Abstract

<div class="section abstract"><div class="htmlview paragraph">In order to solve the problems of the shuffle caused by internal and external excitation and the difficulty in obtaining the real-time accurate engine torque during the parallel mode operation of hybrid electric vehicles, a dynamic coordination control strategy for suppressing the jitter of hybrid electric vehicles based on the closed-loop control of engine speed was proposed. The engine torque filtering control method based on the slope limit was adopted to limit the rate of change of the engine torque and reduce the impact caused by the sudden change of the engine torque; the engine speed closed-loop control method was used to take the motor speed which is easy to be measured accurately in real time as the feedback control variable, which solved the problem of the real-time accurate estimation of the engine torque online. In parallel mode, the motor torque accounts for a small proportion because the torque distribution method gives priority to the engine. When the amplitude of the engine speed is greater than that of the motor speed and the phase of the engine speed is different from that of the motor speed, if the motor damping control is still adopted, the engine speed jitter cannot be eliminated due to the phase difference. In order to suppress the engine torsional vibration in parallel mode and ensure the good acceleration ability of the system, an active damping control strategy based on the engine speed control was proposed. Kalman filter algorithm is used to calculate the target engine speed signal, and the difference between the target speed and the actual speed is processed by a series of low pass filter, double derivative filter and two-stage series lead correction, forming a compensation torque component and superimposed on the engine torque to suppress the speed fluctuation, thereby increasing the system damping and enabling the system to achieve stable acceleration. In this paper, two-stage series lead phase filter is selected to increase the lead phase in the control system, so as to improve the damping of the transmission system with insufficient natural damping in a closed-loop sense. The center frequency of the filter is set as the natural frequency of the powertrain. A simulation platform is set up by using Matlab/Simulink. The simulation results show that the proposed dynamic coordination control strategy can reduce the fluctuation of the engine speed and vehicle speed, and effectively improve the ride comfort of the hybrid electric vehicle.</div></div>