An Optimized Control Strategy for Parallel Hybrid Electric Vehicle

A systematic process of optimization is suggested to obtain the best control maps for a parallel type hybrid electric vehicle. Taking the fuel consumption as the cost function and driving cycle as part of the constraints, an optimization problem for CVT pulley ratio control and motor torque control can be formulated. The change of the battery charge state between the start and end point of the given driving cycle also works as a constraint.

In order to see the effect of various control strategies on system behavior and overall fuel consumption, a simulation model was built to accommodate the functional blocks representing hybrid powertrain subsystem components and corresponding control units. The aforementioned control strategies were tested and validated on this simulation model and finally tested on a prototype vehicle powered by 1.6 liter gasoline engine and 12kW engine mounted permanent magnet motor to demonstrate the effectiveness of the hybrid system on fuel economy improvement and performance.