A Multi-Mode Four-Switch Buck-Boost Derived DC-DC Converter with an Intermediate Battery Interface for Solar Thermoelectric Generation

This paper introduces a multi-mode four-switch buck-boost derived dc-dc converter designed for processing power produced from waste heat using thermoelectric generators (TEGs). TEGs comprise semiconductor thermocouples which generate electricity when exposed to a temperature gradient. Depending on this temperature gradient, TEGs can generate a wide range of voltages. The proposed converter needs to convert this wide range of voltage and deliver power to both 3.7 V Lithiumion battery and 5 V loads. Thus, a multi-mode power converter with four operational modes, buck, boost, buck with boost in passthrough, and buck and boost, is proposed. The implementation of the gate drive circuitry for a back-to-back switch configuration used for controlling the state of charge of the battery and providing short-circuit protection is discussed. The design and optimization of the magnetics considering all modes of operation is also presented. A 50-W prototype converter designed for input voltage range of 5-15 V from the TEGs is designed, built, and tested. The prototype multi-mode converter achieves a peak efficiency of 98.15%.