High Step-Up DC/DC Topology and MPPT Algorithm for Use With a Thermoelectric Generator

A thermoelectric generator (TEG) is a low-voltage high-current dc power source with a linear V-I characteristic, and therefore, it is desirable to create a power converter with a topology and control method suited to these attributes. Due to the TEG's low voltage, a topology that produces a high step-up gain for a moderate duty cycle is required to reduce voltage and current stresses within the converter. The linear V-I characteristic produces a P-I characteristic with a flatter peak relative to other sources. This can result in large operating point variations while performing maximum power point tracking (MPPT); thus, an algorithm with low steady-state error is desired. This paper presents a novel high step-up dc/dc converter topology operating with a fractional short-circuit MPPT algorithm for use with a 4.2-V, 3.4-A (for matched load at Delta T = 270 degrees C) TEG module and a converter output of 180 V. Compared to existing high step-up dc/dc converters, the proposed converter achieves higher gain with similar component count. Experimental results are reported to confirm the converter analysis and better performance of the short-circuit MPPT algorithm over the perturb and observe algorithm.