An optimized MPPT circuit for thermoelectric energy harvester for low power applications

A novel approach of maximum power point tracking (MPPT) control method for thermoelectric generator (TEG) is reported in this paper. The maximum power point tracking is achieved by using impedance matching principle. Unlike the existing MPPT methods, the proposed implementation does not require any voltage and current sensors and computations of any nature. The implementation of the MPPT control circuit is carried out using buck-boost DC/DC converter and a simple gating signal generator using only one Op-amp. The proposed method needs the least power consumption of the MPPT control circuit less than 250μW. Experimental tests results obtained from series connected 3xTEGs (24 mm × 6 mm) show an average power harvesting of 5.6mW at ΔT of 24°C. The proposed thermoelectric energy harvester is used to power a battery which subsequently feeds a sensor node. The low power thermoelectric energy harvester system provides an overall power management circuit efficiency of up to 85%. The efficiency calculation takes care of power losses in the MPPT circuit.