Maximum Power Point Tracking Converter Based on the Open-Circuit Voltage Method for Thermoelectric Generators

Abstract

Thermoelectric generators (TEGs) convert heat energy into electricity in a quantity dependent on the temperature difference across them and the electrical load applied. It is critical to track the optimum electrical operating point through the use of power electronic converters controlled by a maximum power point tracking (MPPT) algorithm. The MPPT method based on the open-circuit voltage is arguably the most suitable for the linear electrical characteristic of TEGs. This paper presents an innovative way to perform the open-circuit voltage measure during the pseudonormal operation of the interfacing power electronic converter. The proposed MPPT technique is supported by theoretical analysis and used to control a synchronous Buck-Boost converter.The prototype MPPT converter is controlled by an inexpensive microcontroller, and a lead-acid battery is used to accumulate the harvested energy. Experimental results using commercial TEG devices prove that the converter accurately tracks the maximum power point during thermal transients. Precise measurements in the steady state show that the converter finds the maximum power point with a tracking efficiency of 99.85%.

An Area Efficient Thermal Energy Harvester With Reconfigurable Capacitor Charge Pump for IoT Applications

“…Even with two dimensional (2D) MPPT, input impedance matching range has not been expanded and the available output power is up to 50 µW. Alternatively, the system [10] senses an open circuit voltage of an energy harvest source to compare the input voltage of the system. At the maximum power point, a half of the open circuit voltage is the same as the input voltage of an energy harvester.…”

“…10 shows the parasitic capacitance, C par , to the digital coded capacitance. As previously mentioned in section 3.3 for design trade-off, increasing the bias current of the DCO reduces a sensitivity of C par to f sw .…”

Adaptive Maximum Power Point Finding Using Direct V OC/2 Tracking Method With Microwatt Power Consumption for Energy Harvesting

“…Many energy harvesters exhibit an almost linear I-V electrical characteristic and therefore can be modeled as a voltage source with a magnitude of V OC and an equivalent serial resistor R e [5], [15]. The magnitudes of V OC and R e mainly correspond to the environmental conditions, for example, temperature difference for TEGs or vibration amplitude and frequency for PEHs.…”

“…This occurs at the half open-circuit voltage V OC /2 of energy harvesters such as thermoelectric generators (TEG) [5], and radio frequency rectennas [6], piezoelectric energy harvesters (PEHs) which are generally weakly coupled [7], and around 0.75 to 0.8 V OC for photovoltaic (PV) cells [8]. The circuits which adopted this method can be implemented using full analog discrete component [6] or mixed-signal circuits which involve a sensing capacitor and more subsystems, for example, switch controller [3], or digital controller [4] to perform the FOCV finding algorithms and controls.…”

Adaptive design of a prototype electricity-producing biomass cooking stove

“…Previous studies using this basic circuit have shown that the system approaches the maximum power point when the temperature difference across the TEG is close to or above 150°C (Kinsella et al, 2014;O'Shaughnessy et al, 2014). Sophisticated maximum-power-point-tracking (MPPT) techniques such as those investigated in Ko Ko et al (2011), Montecucco and Knox (2015), Sungkyu et al (2010), and Xiaodong et al (2010) were not employed.…”