Development of Torque-Speed Control Algorithms For Power-Split Hybrid Electric Vehicle

In the last few years, there has been speedily developing and popularizing of hybrid electric vehicle (HEV) in the market. There are varieties of HEV types, and the degree to which they function as electric vehicle varies as well. HEVs make use of efficiency-improving technology to improve fuel consumption and emissions. Especially, the power-split HEV has combined the advantages of series and parallel hybrids. The control algorithms of the HEV have been developed diversely. These algorithms depended on the configuration of HEV and main components such as internal combustion engine, motors/generators, battery, and power-split device. Moreover, the control strategy is “the heart” of HEV, and it is very complex. Therefore, to improve performances of HEV, the control strategy must be developed and perfected. This study focused on developing control strategies of power flow in power-split HEV system. Based on the analysis of efficiency in a representative driving cycle, two control strategies, rule-based and fuzzy torque control strategies, were developed to optimize the power management of the power-split HEV. The first proposed control strategy was designed with “if-then” rules to control on or off internal combustion engine (ICE) and traction motor. The second one, the fuzzy-based controller, was developed with fuzzy logic to control ICE and motor. The simulation results of the proposed HEV control strategies were compared the fuel economy with real HEV. The power-split HEV model had been built with Matlab/Simulink package, and the simulation results showed significant improvements in fuel consumption.