Development and Performance Assessment of a Hydraulic Hybrid System

Abstract

Abstract The automotive industry has for some years considered hydraulic regeneration systems for use in hybrid vehicles; combining the concurrent use of an internal combustion engine and a hydraulic system to reduce fuel consumption and increase performance. This study describes the development of a hydraulic hybrid system using a small passenger vehicle (SPV) model and a hydraulic hybrid pump/motor (P/M) model. A model of an SPV vehicle was developed and validated using MATLAB Simulink. Simulations were performed to analyse and test the performance of the hybrid system. This study addresses the gap related to the prediction of the performance of the hydraulic hybrid system for use on an SPV. A novel control system was developed to simulate the drive cycle and predict the fuel-saving of the hydraulic hybrid system. Variables included accumulator size, hydraulic P/M displacement and accumulator pre-charge, which were adjusted to optimise the hydraulic hybrid system. The Fuel consumption of the model before the implementation of the hybrid system was calibrated with the recorded fuel consumption of the test vehicle. The hydraulic hybrid system was then developed and implemented to the SPV model along with a revised control system. The fuel-saving of a novel hydraulic hybrid control was estimated using MATLAB Simulink. A controller was developed to manage the distribution of energy between the hydraulic system and the diesel engine. The effects of the hybrid system on the brakes and the engine demand were analyzed. The results indicated a 45% reduction in diesel engine demand and a 65% decrease in brake usage throughout the drive cycle. The model of the hydraulic hybrid passenger vehicle predicted a fuel saving of approximately 17%. This study shows that the hydraulic hybrid system can potentially improve fuel consumption and optimize engine performance in passenger vehicles.