The Simulation Study of HEV Under Electric Assist Control Strategy （EACS）

Hybrid Electric Vehicle (HEV) becomes a popular research project all over the world because of its high efficiency and low emissions. HEV is driven by Internal Combustion (IC) engine and electric motor, and its powertrain is more complex than conventional vehicle. Therefore, the complexity of a HEV powertrain demands a reliable control strategy be developed to guarantee stable and consistent operation. In this paper, EACS is proposed which takes IC engine as a main power unit and the electric motor as an assistant one. Because the fuel consumption of HEV mainly depends on IC engine, EACS restricts the IC engine to operate under the condition with favorable fuel economy. In the paper several control parameters are described such as the maximum torque, the lowest and highest desired battery state of charge (SOC), whose values will affect the performance of HEV remarkably. In addition, the test models of power units for HEV, mathematical models of transmission and vehicle dynamics for HEV are established. A forward-facing simulation software (i.e. driver-to-wheel) based on MATLAB/Simulink is developed to test the performance of EACS and determine the proper value of the control parameters. The simulation results and conclusion are also shown in the paper.