SPICE model identification technique of a cheap thermoelectric cell applied to DC/DC design with MPPT algorithm for low-cost, low-power energy harvesting

In this work, an identification technique of a simple, measurements-based SPICE (Simulation Program with Integrated Circuit Emphasis) model is presented for small low-cost Peltier cells used in thermoelectric generator (TEG) mode for low-temperature differences. The collection of electric energy from thermal sources is an alternative solution of great interests to the problem of energy supply for low-power portable devices. However, materials with thermoelectric characteristics specifically designed for this purpose are generally expensive and therefore often not usable for low cost and low power applications. For these reasons, in this paper, we studied the possibility of exploiting small Peltier cells in TEG mode and a method to maximize the efficiency of these objects in energy conversion and storage since they are economical, easy to use, and available with different characteristics on the market. The identification of an accurate model is a key aspect for the design of the DC/DC converter, in order to guarantee maximum efficiency. For this purpose, the SPICE model has been validated and used in a design example of a DC/DC converter with maximum power point tracking (MPPT) algorithm with fractional open-circuit voltage. The results showed that it is possible to obtain a maximum power of 309 μW with a Peltier cell 2 × 2 cm at a DT of 16 °C and the designed SPICE DC/DC converter performance proved the improvement and optimization value given by the TEG model identification.