A simple power based control strategy for hybrid electric vehicles

The high cost of fossil fuel and environmental concerns forced the automotive industry to seek innovative ways to improve gas mileage. The short term solution to these concerns is the concept of hybrid electric vehicles (HEV) that combines the use of an internal combustion engine (ICE) and an electric motor (EM). The energy of the battery used by a HEV can come from renewable sources such as solar and wind energy. It can also come from the energy recovered while decelerating the vehicle. The use of hybrid vehicles creates new control challenges in the area of energy management. The objective of this paper is to design and test a simple automatic control strategy to simplify the energy management problem of HEV. The main idea is to control the electric motor to provide the power needed to meet the minimum torque requirement, under no load condition and flat road, at different speed ranges of the vehicle. The remaining power will be provided by the ICE. The minimum torque and corresponding power will be determined using the vehicle model. Contrary to existing power management approaches, the proposed strategy does not require sophisticated optimization techniques nor use ad hoc rules that are difficult to tune. In addition, the proposed strategy is simple to implement as it requires only the knowledge of the vehicle speed and battery state of charge. The proposed control strategy was tested using a 2000 Honda Insight vehicle that was modeled using ADVISOR 2002 vehicle simulator. Preliminary simulation results show that the proposed control strategy can improve the gas mileage of the Honda Insight by as much as 50%.