Energy management strategy of a plug-in hybrid electric vehicle based on a thermoelectric generator

Abstract

Abstract

Plug-in hybrid electric vehicles (PHEVs) are an important transition technology for reducing petroleum consumption and exhaust emissions, but their overall energy efficiency is still limited by engine waste heat and battery SOC fluctuation during hybrid operation. Thermoelectric generators (TEGs) provide a direct way to recover part of the exhaust heat and convert it into usable electrical energy. However, the recovered TEG power is usually small and strongly dependent on engine thermal conditions, so its benefit can only be fully reflected when it is coordinated with the vehicle energy management strategy. To address this issue, this study develops a TEG-assisted PHEV powertrain model and proposes a TEG-aware rule-based energy management strategy (EMS). The model couples the engine, battery, electric motor, transmission, and TEG system in AVL CRUISE and MATLAB/Simulink. The EMS determines the vehicle operating mode from demanded torque, SOC limits, engine efficient operating regions, and recovered TEG power availability. Its main novelty is that the recovered TEG power is explicitly embedded into rule-based mode switching and power allocation: when TEG power is available, it is used to support the DC bus, reduce battery discharge, or charge the battery according to the SOC state. The TEG output model, PHEV power-flow equations, and SOC dynamics are introduced to clarify the energy transfer mechanism. Comparative simulations are conducted under the NEDC cycle using a baseline PHEV without TEG and a TEG-assisted PHEV. The results show that the TEG-assisted model tracks the target speed effectively, recovers 152.91 kJ of exhaust waste heat energy, reduces fuel consumption from 5.84 L/100 km to 5.49 L/100 km, and decreases SOC variation from 4.32% to 1.72%. These results correspond to a 5.99% fuel-consumption reduction and a 60.19% improvement in SOC stability, demonstrating that coordinated utilization of TEG power can improve both fuel economy and battery charge-sustaining performance.