PHEV Modeling:
Control Strategy Assessment of PHEVs

A generic global optimization algorithm for plug-in hybrid electric vehicle (PHEV) powertrain flows has been developed based on the Bellman optimality principle. Optimization results are used to isolate control patterns, both dependent and independent of the cycle characteristics, in order to develop real-time control strategies in Simulink/Stateflow. These controllers are then implemented in PSAT to validate their performances.

Heuristic optimization algorithms (such as DIRECT or genetic algorithms) are then used to tune the parameters of the real-time controller implemented in PSAT.

The control strategy development process is described below.

Control Strategy Development Process

The global optimization algorithm showed that using charge-depleting, rather than all electric mode followed by charge sustaining mode, was more efficient. As shown in the figure below, the algorithm highlighted the importance of knowing the distance to properly minimize the amount of fuel consumed.

PHEV Optimum Control Strategy Depends on Distance

May 2008