Andrea Montecucco

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

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%.

Facile Surfactant‐Free Synthesis of p‐type SnSe Nanoplates with Exceptional Thermoelectric Power Factors

Abstract A surfactant‐free solution methodology, simply using water as a solvent, has been developed for the straightforward synthesis of single‐phase orthorhombic SnSe nanoplates in gram quantities. Individual nanoplates are composed of {100} surfaces with {011} edge facets. Hot‐pressed nanostructured compacts (E g≈0.85 eV) exhibit excellent electrical conductivity and thermoelectric power factors (S 2 σ) at 550 K. S 2 σ values are 8‐fold higher than equivalent materials prepared using citric acid as a structure‐directing agent, and electrical properties are comparable to the best‐performing, extrinsically doped p‐type polycrystalline tin selenides. The method offers an energy‐efficient, rapid route to p‐type SnSe nanostructures.

Simple, fast and accurate maximum power point tracking converter for thermoelectric generators

Thermoelectric generators (TEGs) can harvest thermal energy producing electrical power from a temperature gradient. They are often employed in dynamic thermal environments, therefore it is important to quickly and precisely track the best operating point to maximize the power production. This paper presents an innovative way to measure the open-circuit TEG voltage without disconnecting the load, to be used in a Maximum Power Point Tracking (MPPT) algorithm based on the open-circuit voltage method. The proposed system is composed of a buck converter with embedded microcontroller, which is used both to compute the MPPT algorithm and to control the charging of a lead-acid battery. The prototype converter is tested using a TEG system and it can accurately set the optimum operating point almost instantaneously and without significant computational power requirements.

Scalable solar thermoelectrics and photovoltaics (SUNTRAP)

This paper presents the design, manufacture and electrical test of a novel integrated III:V low concentrator photovoltaic and thermoelectric device for enhanced solar energy harvesting efficiency. The PCB-based platform is a highly reliable means of controlling CPV cell operational temperature under a range of irradiance conditions. The design enables reproducible data acquisition from CPV solar cells whilst minimizing transient time for solid state cooling capability.

Hardware Implementation of Maximum Power Point Tracking for Thermoelectric Generators

This work describes the practical implementation of two maximum power point tracking (MPPT) algorithms, namely those of perturb and observe, and extremum seeking control. The proprietary dSPACE system is used to perform hardware in the loop (HIL) simulation whereby the two control algorithms are implemented using the MATLAB/Simulink (Mathworks, Natick, MA) software environment in order to control a synchronous buck–boost converter connected to two commercial thermoelectric modules. The process of performing HIL simulation using dSPACE is discussed, and a comparison between experimental and simulated results is highlighted. The experimental results demonstrate the validity of the two MPPT algorithms, and in conclusion the benefits and limitations of real-time implementation of MPPT controllers using dSPACE are discussed.

Megawatt scale energy recovery in the Rankine cycle

It has, in recent times, become the focus of national and international political pressure to reduce the impact of climate change [1]. The amount of CO2 that is released to the atmosphere now has legislative and tax implications with CO2 emitters around the world in both developed and developing countries having to implement CO2 reducing technologies to reduce costs and maintain profitability [2]. We aim to exploit the Peltier effect exhibited in semiconductor devices to create an enthalpy capture device using the significant amount of energy rejected by such a power plant. A thermoelectric device applied in its heat pumping mode, enables the redirection of energy released in the condensation process. We aim to prove that using the thermoelectric device in a particular configuration enables the preheating of water returning to the boiler (feed water). Such an application of a heat pumping device will increase the net efficiency of the Rankine cycle.

Outdoor performance of a reflective type 3D LCPV system under different climatic conditions

Concentrating sunlight and focusing on smaller solar cells increases the power output per unit solar cell area. In the present study, we highlight the design of a low concentrating photovoltaic (LCPV) system and its performance in different test conditions. The system essentially consists of a reflective type 3.6× cross compound parabolic concentrator (CCPC) designed for an acceptance angle of ± 30°, coupled with square shaped laser grooved buried contact (LGBC) silicon solar cells. A heat exchanger is also integrated with the PV system which extracts the thermal energy rejected by the solar cells whilst maintaining its temperature. Indoor characterization is carried out to evaluate the system performance under standard conditions. Results showed a power ratio of 3.12 and an optical efficiency of 73%. The system is placed under outdoor environment on a south facing roof at Penryn, UK with a fixed angular tilt of 50°. The high angular acceptance of the system allows collection of sunlight over a wider rang...

Indoor characterization of a reflective type 3D LCPV system

Low concentrating photovoltaic (LCPV) systems produces higher electrical output per unit solar cell compared to typical PV systems. The high efficiency Si solar cells can be utilized with little design and manufacturing changes for these applications. However, a key barrier towards achieving economic viability and the widespread adoption of LCPV technologies is the losses related to high operating temperature. In the present study, we evaluate the performance 3D low concentration system designed for 3.6×, using a reflective Cross compound parabolic concentrator (CCPC) and a Laser Grooved Buried Contact solar cell having an area of 50*50mm2. Results demonstrate the losses occurring due to the temperature rise of the solar cell under concentration and we analyze the potential which could be utilized for low grade heating applications.