Application of New SEUMRE Global Optimization Tool in High Efficiency EV/PHEV/EREV Electric Mode Operations

Electric Vehicles (EV), Hybrid Electric Vehicles (HEV), Plug-in Hybrid Electric Vehicles (PHEV) and Extend Range Electric Vehicles (EREV) draw mechanical power or regenerate electric power using multiple electric motors and generators (M/Gs). Conventionally, heuristics and experience based control rules are used to guide the determination of powertrain component operation parameters to obtain good efficiency. To achieve optimal vehicles electrical/mechanical energy conversion efficiency and to prolong the pure electric range of these vehicles, the energy conversion efficiency is to be maximized against powertrain component operation parameters using high fidelity model and simulation. However, the energy conversion efficiency model using vehicle powertrain component model and simulation is complex, multimodal, and computationally intensive. An efficient global optimization tool is needed to produce the optimal efficiency look-up surface for real-time control system implementation, or to search for the optimal operation parameters in real time. In this work, the electrical/mechanical energy conversion efficiency of EV and PHEV/EREV in EV mode is modeled using MATLAB Simulink based powertrain component models. In particular, a new 2 mode-plus EREV design is used as a design example. The optimal vehicle electrical/mechanical energy conversion efficiency under various powertrain component operation parameters are obtained using three alternative global optimization tools, Genetic algorithm (GA), Particle Swarm Optimization (PSO) and Space Exploration and Unimodal Region Elimination (SEUMRE). The conventional GA and PSO tools, with less efficient search efficiency and requiring long search time, are used for benchmark comparisons. The new SEUMRE global optimization tool is used obtain equally accurate results much efficiently. A rough look-up surface is created to demonstrate the difference in computational efficiency. Application of the SEUMRE global optimization tool allow refined and more accurate vehicle electrical/mechanical energy conversion efficiency map being created for the optimal operation of the EV/PHEV/EREV Optimal vehicle control schemes can then be generated in determining the speed and torque of the M/Gs of the vehicle without violating their physical constraints and achieving the overall maximum efficiency of the hybrid powertrain system. Results of the design optimization are presented and compared. New design guidelines are provided.