Two-level energy harvesting strategy for multi-input thermoelectric energy system

Abstract

The inevitable non-uniform temperature distribution across a large number of thermoelectric modules can cause reduced output power of the automotive exhaust thermoelectric generator (AETEG). In order to achieve accurate tracking of maximum power point for an AETEG, a distributed thermoelectric energy recovery system is proposed consisting of several parallel thermoelectric generators and a lithium-ion battery pack. And then, a two-level energy harvesting strategy is developed to efficiently recover exhaust energy under dynamic driving cycles. The simulated results based on an experimentally validated system model under the modified Highway Fuel Economy Test (HWFET) for a commercial heavy-duty vehicle demonstrate that the proposed strategy enables the system to run at the efficient working point of DC/DC converters. It shows that the charging energy can be increased by 174013 J and the efficiency of system-control level can be raised by 2.4% compared to the conventional feedback control under the modified HWFET driving cycle, when the initial State of Charge (SOC) of the battery pack is 10%. Meanwhile, the proposed strategy can avoid the over-charging events for the battery pack since it can be effectively controlled along its pre-defined optimal working trajectory, which is verified by the campus road test.