Transient response of a thermoelectric generator to load steps under constant heat flux

Abstract

Most waste heat recovery applications involve a heat source that provides a limited heat flux that can be converted into electricity by a thermoelectric generator (TEG). When a TEG is used under limited or constant heat flux conditions the temperature difference across the device cannot be considered constant and will change depending on the electrical current generated by the TEG. This phenomenon is induced by the Peltier effect, which works against power generation and deviates the optimum operating point from the commonly known maximum power point (MPP). This point, dictated by the maximum power transfer theorem, is achieved when the source equivalent series resistance and the load resistance are equal, in conditions of constant temperature difference. Hence maximum power point tracking (MPPT) algorithms that regulate the TEG at half of the instantaneous open-circuit voltage are optimized only for applications where the TEG operates under constant temperature difference but are not ideal for constant heat flux conditions. Hill climbing MPPT methods, e.g., perturb-and-observe (P&O) or incremental conductance (IC), can reach the MPP more accurately if the sampling time is extended to the thermal time constant of the system. This article presents an analysis of the transient electrical and thermal response of a TEG to a load change. This investigation results fundamental to the design of MPPT algorithms such P&O or IC for TEGs operating under constant heat flux. A step-up (boost) dc-dc converter controlled by P&O is used to demonstrate the effects of the sampling time over of the transient response and hence the tracking performance of the MPPT algorithm. 1.

A hybrid analytical‐computational method for three dimensional modeling of thermoelectric generators

“…Several mathematical models of thermoelectric modules are proposed such as standard simplified models, improved simplified models and complex TE models. 3 Based on the employed models, researchers tend to account 6,15,[17][18][19]31 or neglect 5,8,[12][13][14]29,38,39 the Thomson effect in their investigations. In this regard, the influence of Thomson effect on the present model is also investigated to see the impact of this term on power output of the module.…”

A MPPT based on optimized FLC using manta ray foraging optimization algorithm for thermo‐electric generation systems

“…19,20 The perturb & observe (P&O) and hill climbing (HC) MPPT methods represent the commonly applied MPPT controllers for TEG systems in the literature. [21][22][23] The P&O operates in alternating manner for the TEG set point through continuously observing whether the outputted TEG power is increasing or decreasing. Afterward, it decides the operating duty cycle decision with increase/decrease in accordance by fixed step from the current values.…”

Parameter Identification of Optimized Fractional Maximum Power Point Tracking for Thermoelectric Generation Systems Using Manta Ray Foraging Optimization

“…Hill climbing (HC), and perturb and observe tracking (P&O) are the frequently used approaches for TEG systems in the literature [9][10][11], thanks to their simplicity in implementation. The main drawback of such approaches is the high fluctuations around the MPP at steady-state condition.…”