Thermoelectric Generator Output Research Articles

Impacts of distributed thermal and electric contact resistance on performance and geometric optimization of thermoelectric generators

Thermal and electric contact resistance (TCR/ECR) critically impact performance and geometric optimization of thermoelectric generators (TEGs). However, conventional treatments usually ignored or simplified them as lumped variables, neglecting their actual distributions across the TEG system. In this study, we proposed a multi-physical model to characterize TEG performance with explicitly specifying TCRs/ECRs at different TEG interfaces (locations). The numerical results show that the lumped-variabletreatment led to maximal overestimations of 16.9 % and 24.5 % in the TEG output power and efficiency, respectively, compared to the results with distributed TCR in this article. Importantly, it also reveals that the TEG performance was susceptible to the TCR location—the interfaces on the cold side exerted more negative impacts than those on the hot side. Furthermore, reducing both TCR and ECR could improve TEG performance and reducing TCR is more effective. It is shown that an 80 % reduction in TCR increased the maximum TEG output power by 35.6 %, while the same reduction percentage in ECR only improved it by 8.8 %. As to geometric optimization, an optimal TE leg height equal to 0.6 mm was obtained for the maximum output power. This contrasts with previous studies without considering TCR and ECR, which always favoured shorter heights. As for copper electrodes, their optimal heights were in the range of 0.2–0.4 mm corresponding to the maximum efficiency, far smaller than those (0.7–1.2 mm) obtained when TCR/ECR were neglected. The latter even further resulted in a reduction in the maximum efficiency by more than 1 % compared to its true peak. In this study, all these numerical results clearly elucidate the important impacts of distributed TCR and ECR on TEG performance, and provide a comprehensive and balanced guideline for TEG design.

Efficiency Enhancement in Ocean Thermal Energy Conversion: A Comparative Study of Heat Exchanger Designs for Bi2Te3-Based Thermoelectric Generators.

This research focuses on enhancing the efficiency of Bi2Te3-based thermoelectric generators (TEGs) in ocean thermal energy conversion (OTEC) systems through innovative heat exchanger designs. Our comparative study uses computer simulations to evaluate three types of heat exchangers: cavity, plate-fins, and longitudinal vortex generators (LVGs). We analyze their impact on thermoelectric conversion performance, considering the thermal energy transfer from warm surface seawater to TEGs. The results demonstrate that heat exchangers with plate-fins and LVGs significantly outperform the cavity heat exchanger regarding thermal energy transfer efficiency. Specifically, plate-fins increase TEG output power by approximately 22.92% and enhance thermoelectric conversion efficiency by 38.20%. Similarly, LVGs lead to a 13.02% increase in output power and a 16.83% improvement in conversion efficiency. These advancements are contingent upon specific conditions such as seawater flow rates, fin heights, LVG tilt angles, and locations. The study underscores the importance of optimizing heat exchanger designs in OTEC systems, balancing enhanced heat transfer against the required pump power. Our findings contribute to a broader understanding of materials science in sustainable energy technologies.

Optimal dynamic reconfiguration of thermoelectric generator array using RIME optimizer to maximize the generated power

The innovation of green and flexible sources of electricity is identified as one of the key enablers to a more electric-dependent world aiming at meeting the technology needs and promised sustainability goals. The thermoelectric generator device is one of these innovative sources as it directly converts the wasted heat to electric power with a cheap, silent, and no-emissions process. Yet, the power output of the thermoelectric generator is primarily based on the temperature distribution on its sides. Towards efficiently saving the wasted heat and maximizing the output power of the thermoelectric generator, optimizing the configuration for the thermoelectric generator array is paramount. In this regard, this paper proposes an optimal dynamic reconfiguration for several design options of the thermoelectric generator array, including series–parallel, total-cross-tied, bridge-linked, and honey-comp, to better enhance the thermoelectric generator array output power under nonuniform temperature distribution. The proposed dynamic reconfiguration approach is mathematically formulated as a maximization optimization problem for the thermoelectric generator array output power. The physics-based optimization of RIME is tailored to provide the optimal array reconfiguration layout that realizes the maximum power, upon which the overall power loss is potentially decreased, and the energy conversion efficiency is significantly improved. The efficacy and superiority of the proposed configuration types and optimal dynamic reconfiguration technique are assessed for two sizes of the thermoelectric generator array: a symmetric 9x9 array and an asymmetric 10x15 array. A detailed analysis is conducted to compare the thermoelectric generator output power of the studied configurations without and with the proposed dynamic reconfiguration technique. The results affirm that optimized dynamic reconfiguration significantly enhances the thermoelectric generator array-generated power. One of the key observations from the results is that employing a dynamic reconfiguration for the bridge-linked type yields up to a 10% increase in the output power of the thermoelectric generator array compared to the design options without reconfiguration. Also, the results show that the dynamically reconfigured bridge-linked type could yield about a 5% increase in the produced output power compared to other dynamically reconfigured design options.

Numerical investigation of a thermoelectric generator system with embedded sickle-shaped fins

To enhance the utilization efficiency of exhaust gas in thermoelectric generator (TEG) systems, a polygonal heat exchanger with embedded sickle-shaped fins was proposed in this study. A coupled fluid-thermal-electric multiphysics numerical model was developed to analyze the impact of different fin variables on system performance. Subsequently, the established model was validated on a test bench. The results indicate that embedded sickle fins significantly improve the TEG performance. Higher fins enhance the system's output power and temperature uniformity, albeit with increased pressure drop. Conversely, elongated linear fins and increased arc fin radius decrease pressure drop but reduce its output power. Additionally, increasing the end angle of the arc improves temperature uniformity with minimal effect on output power and pressure drop. Moreover, the TEG system exhibits optimal performance when the linear fin length is 180 mm, the height is 45 mm, the radius of arc fins is 305 mm and the end angle is 8°. At the inlet air temperature of 600 K and the velocity of 40 m/s, the TEG output power, temperature uniformity coefficient and pressure drop for this configuration are 116.59 W, 0.99 and 845 Pa, respectively. This work contributes a theoretical reference for the structural optimization of low-backpressure TEG systems in future automotive exhaust applications.

Thermo-economic and performance analysis of a novel tubular hybrid high-temperature proton exchange membrane fuel cell and thermoelectric generator

This paper proposes a novel tubular design for a hybrid high-temperature proton exchange membrane fuel cell (HT-PEMFC) and thermoelectric generator (TEG) system. The wasted heat from the fuel cell is captured by a thermoelectric generator to generate more electricity. Hence, the primary objective of the research is to determine the waste heat recovery performance of the TEG for thermal management of the tubular HT-PEMFC. A validated 3D numerical approach was employed to evaluate the performance of the tubular hybrid system with a tubular TEG integrated into the HT-PEMFC. A parametric study evaluates the impact of various TEG geometrical configurations and operational parameters on the system's performance. The results indicate that boosting the cell voltage improves the fuel cell efficiency, while decreasing the thermoelectric sizing has a notable impact on the TEG's performance. The TEG's conversion efficiency and output power are significantly impacted by changes in the angle ratio and the temperature of the cold side. Increasing the inlet temperature has a positive impact on thermoelectric power generation but leads to a reduction in fuel cell power and efficiency. Overall, the study highlights the importance of optimizing the operating conditions of hybrid tubular HT-PEMFC/TEG to achieve optimal performance and provides valuable insights for the design and development of hybrid energy systems that can potentially contribute to meet the increasing demand for sustainable energy solutions.

Performance assessment of the hybrid PV-MCHP-TE system integrated with PCM in all-day operation: A preliminary numerical investigation

Regarding the existing research on photovoltaic (PV) and thermoelectric generator (TE) integrated systems mostly focus on their daytime behaviors, a solar system that can achieve continuous electrical supply throughout the day, namely the PV-TE system with the micro-channel heat pipe (MCHP) (the PV-MCHP-TE system), is proposed in this paper. The implementation method is to use the phase change material (PCM) which releases the heat it harvests during the day to maintain the uninterrupted electrical output of TE at night, on the basis of the system generating electricity through PV and TE by day. Considering that the system performance may change with the difference in cooling effects, three PV-MCHP-TE systems adopting different cooling methods are designed and their performance changes during a continuous working week are analyzed. The results show that the daytime average electrical efficiencies of PV in the systems using free cooling, forced air cooling, and water cooling are 9.33%, 11.85%, and 13.10%. The maximum electrical efficiencies of TE in the three systems are 0.47%, 1.48%, and 1.87%, and the nighttime average efficiencies are 0.13%, 0.15%, and 0.16%, respectively. Additionally, a comparative analysis is also performed to compare the performance of the considered systems under different PCM parameters.

Improving the ability of thermoelectric generators to absorb industrial waste heat through three-dimensional structure optimization

A large amount of waste heat in the industrial sector is lost to the environment in the form of radiant heat, causing serious energy loss. In this study, thermoelectric conversion technology is used to recover industrial radiant heat, and the ability of the thermoelectric generator (TEG) to absorb radiant heat is effectively improved by optimizing the heat collector's structure. In order to reduce the research cost, the heat transfer process between the industrial environment and TEG is analyzed by a numerical calculation method. According to the numerical calculation results, the influence of the heat collector's structure on the power generation performance is analyzed, and the optimal structure scheme is determined. Finally, the accuracy of the research results is verified by industrial experiments. This study makes up for the need for related research through many industrial experiments. The results show that increasing the height and number of heat collecting fins will increase the hot end temperature of the heat collector. When the number of fins is 19, and the height is 8 cm, TEG's total heat absorption and output power are the largest. The total heat absorption is 1.0 kW, and the output power is 38.4 W. The longer the length of the heat collector, the more pronounced the temperature inhomogeneity, leading to an increase in the number of the low-efficiency thermoelectric module (TEM). The number of low-efficiency TEM is the least when L = 50 cm, so the conversion efficiency of the TEG is the largest, and the conversion efficiency is 3.76 %.

Performance analysis of thermoelectric generator system in different aspect ratio collector channels

Rectangular collector channels are widely used in thermoelectric generator (TEG) systems. The aspect ratio greatly influences the heat transfer of the channel and thus affects the TEG output performance. However, the effect of aspect ratio on TEG output performance has not been intensively analyzed. Thus this paper studies the effect of aspect ratio on TEG output performance under the same heated area for the first time and clarifies the reasons for the high output power of low aspect ratio channels. A numerical model of the TEG system is developed, and the model's accuracy is verified. Then, the output performance of the collector channel TEG system with different aspect ratios, such as output power, net power, and heat conversion efficiency, is investigated to obtain the optimal channel aspect ratio. Finally, the effects of the fin number and the load resistance on the output performance of the TEG system are further analyzed. The results show that the TEG system with low aspect ratio channels exhibits better output performance; the TEG system with an aspect ratio of 0.1 has an 18.3% higher output power than the TEG system with an aspect ratio of 1. When the Re number is 2400, the TEG with an aspect ratio of 0.1 has the highest net power of 2.77 W. The lower aspect ratio reduces the collector channel's hydraulic diameter and improves the TEG's heat transfer performance. When the fin number is increased from 16 to 34, the output power increases by 10%, but the lower number of fins exhibits a higher heat conversion efficiency. This study provides some new ideas for improving the output performance of TEG systems.

Experimental Evaluation of Thermoelectric Generator Performance under Different Heat Conduction Boundary Conditions

Heat conduction boundary conditions play a crucial role in the performance of thermoelectric generators (TEG). The TEG output voltage and power were measured under constant temperature boundary and heat flux conditions to evaluate the TEG performance under different heat conduction boundary conditions. External loading pressure and thermal interface material (TIM) were applied to reduce the interfacial thermal contact resistance. In our measurement setup, a fast-response electronic load was used for the rapid current-voltage scan, which can eliminate the thermal drift caused by the Peltier effect. A guard heater arrangement is used to minimize heat loss. In constant temperature boundary conditions, reducing the thermal contact resistance can increase the effective temperature drop across the TEG module and significantly improve the output voltage and power. But in the constant heat flux conditions, since the heat flux flow through the TEG is unchanged, the temperature drop across the TEG was unaffected by the thermal contact resistance. As a result, the TEG performance was lightly influenced by the thermal contact resistance.

Performance analysis of thermoelectric power-generation system with natural convection cooling

Nowadays, high-performance electronic devices release large amounts of heat throughout their operation. Thermoelectric passive cooling systems can offer a cost-efficient and straightforward solution for the thermal management of such devices based on a passive heatsink and a thermoelectric generator (TEG). TEG can transform a part of the heat generated by the electronic chip into electricity for the power supply of microelectronic systems. The thermoelectric system investigated here contains a 12 W Positive Temperature Coefficient (PTC) heating element placed on a 4 × 4 cm2 aluminium plate, a commercial SP1848-27145 TEG device and a finned plate heatsink recycled from a desktop PC. Two types of tests were performed here. An energy efficiency test was initiated at different load resistance values RL between 1 and 40 Ω by directly connecting TEG output to a direct current (DC) electronic load. The second test was developed for electrical power generation at 3.3 V–5 V by integrating a DC–DC boost converter between the TEG output and the electronic load set at RL of 600–900 Ω. It was registered a maximum energy conversion efficiency of 1.17 % for RL=2Ω, close to the internal resistance value of the TEG module. The second test revealed the generation of output electrical powers with minimum values of 15–17.5 mW at a temperature difference between TEG plates of about 20 K.

A New Self-Powered Temperature Sensor Based on Thermoelectric Generators

This article presents a new self-powered temperature sensor based on thermoelectric generators (TEGs). Two different types of TEGs measure temperature and supply the interface circuit. The interface circuit calculates and generates an output current proportional to the cold-surface temperature of the TEGs. Since TEG output voltage depends on the temperature difference between the cold and hot surfaces, a three-terminal TEG has been used. A combination structure of the two PbTe and Bi2Te3 TEGs are thermally in parallel and electrically in series. The new method uses a machine-learning algorithm and Seebeck curve fitting for temperature calculation. For the cold surface temperature range of 0 °C to 70 °C, the error is less than ±1 °C.

Output power leveling of on-chip thermoelectric generator using a solid–solid phase change material

Energy harvesting technology using thermoelectric generators (TEG) is a promising solution to environmental energy problems. Moreover, an on-chip TEG, which can improve the net power consumption of electronic devices, is attracting attention. However, thermal or electrical control is required to stabilize the TEG output for unsteady heat sources, such as electronic chips. In this study, we focused on output power-stabilization technology by thermal control using phase-change materials (PCM). A vanadium dioxide (VO2) sintered body, a solid–solid PCM, was used as the PCM and compared to paraffin, a typical solid–liquid PCM. The power generation performance of the TEG with these PCMs mounted on a thin heat-generating chip was evaluated. The TEG with VO2 exhibited higher power generation and output power leveling performance than paraffin, mainly because it has a higher thermal conductivity than paraffin. Furthermore, in the TEG with VO2 case, the maximum temperature of the heat-generating chip was 14.4 °C lower than that without the PCM, indicating that the on-chip TEG with VO2 could level the temperature of the electronic chip while generating electricity.

Experimental study of harvest solar energy based on thermoelectric generator with configuration variations

The background of this research is to optimize the use of heat from solar energy as energy harvesting based on a thermoelectric generator (TEG). One of the factors that affect the TEG output is the TEG configuration and the resulting temperature difference. The external temperature captured by the TEG side and the cooling system causes a significant temperature difference. This study uses a TEG trainer module consisting of eight TEGs and a double heatsink that functions for the cooling side and heat capture from the sun. Experiments show that the combination of eight TEG modules in series provides a maximum output significantly compared to single TEG and parallel modules at the same time with a temperature difference of 12.870C.

A 22-m Operation Range Semi-Passive UHF RFID Sensor Tag With Flexible Thermoelectric Energy Harvester

This article presents a wireless temperature sensor tag able to work in both fully passive mode and in semi-passive mode when assisted by a flexible thermoelectric generator (TEG). The sensor tag consists of an EPC C1G2/ISO 18000-6C ultrahigh-frequency (UHF) radio frequency identification (RFID) integrated circuit (IC) connected to a low-power microcontroller unit (MCU) that samples and collects the temperature from a digital temperature sensor. With a temperature gradient as low as 2.5 °C, the test results show that the TEG provides an output power of 400 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu$ </tex-math></inline-formula> W with an output voltage of 40mV. Bymeans of an up-converter in order to boost the TEG output voltage, this harvester supplies the power required to the sensor tag for a 2-conv/s data rate in semi-passive mode. Moreover, when the tag operates in semi-passive mode, a communication range of 22.2 m is measured for a 2-W effective radiated power (ERP) reader. To the best of our knowledge, the proposed TEG-assisted sensor tag shows the longest communication range and the only one that provides stable external power at low-temperature gradients. The measured performance and the chosen architecture allow using the wireless sensor in multiple industrial or biomedical applications.

A comprehensive analytical model for thermoelectric body heat harvesting incorporating the impact of human metabolism and physical activity

Wearable electronic devices, which can provide hassle-free, long-term, continuous monitoring for different health parameters are of interest for a variety of applications including managing chronic diseases and post-operative patient care. Thermoelectric generators (TEGs) that rely on the Seebeck effect provide a promising path to self-powered wearable electronics via harvesting body heat. The net harvested energy depends on several factors including metabolic heat, core body temperature, and skin resistance, which are regulated by the human thermoregulatory system. These factors are influenced by age, sex, height and body mass index (BMI) and they can cause appreciable differences in the amount of harvested energy. In this paper, we present a comprehensive model, which combines an analytical TEG model with established biological models for the human body to accurately predict the performance of a wearable TEG. The model calculates variations in metabolic rate and core body temperature during physical activity, which are then used to calculate the skin resistance and the skin temperature following an iterative procedure. These parameters are then used to determine the temperature differential across the TEG and the resulting output power delivered to an external load. Experimental validation of the model was achieved using a wrist worn flexible TEG during different physical activities, which were carefully designed to separate the impact of convection from the human thermoregulatory response. It was determined that increase in metabolism from normal walking could lead to a 20% increase in the TEG output voltage. The model was used to predict the impact of age and sex on TEG output power. The results indicate that age can have a significant impact on TEG performance. It is shown that the power generated by adults over the age of 65 can be 30%–35% less than the power generated by younger adults under the age of 30. This reduction in power was attributed to an increase in skin resistance, which was found to be 13% for females and 25% for males. The skin resistance of females was also found to be higher, which correlated well with their higher average fat content. The overall impact of sex was found to be smaller than age, females generating 5%–10% less power than males. The model takes into account all pertinent TEG parameters including properties of the semiconductor materials, physical dimensions of the semiconductor legs, fill factor and electrical and thermal parasitic resistances. Using these input parameters, and modeling of the human body as a heat source, the model can help optimize TEG module design for a specific wearable application.

Cleaner energy for sustainable future using hybrid photovoltaics-thermoelectric generators system under non-static conditions using machine learning based control technique

In addition to the load demand, the temperature difference between the hot and cold sides of the thermoelectric generator (TEG) module determines the output power for thermoelectric generator systems. Maximum power point tracking (MPPT) control is needed to track the optimal global power point as operating conditions change. The growing use of electricity and the decline in the use of fossil fuels have sparked interest in photovoltaic-TEG system utilization in the energy sector. Thermoelectric generation systems are meant to recover waste heat as a green energy supply. Concentrated solar can overcome the drawbacks of inefficient power generation. The feasibility of employing a machine learning and metaheuristic-based control strategy to yield maximum power from a hybrid photovoltaic and thermoelectric generator system under various operating situations is examined in this study. The output of both TEG and PV modules is affected by the environment; PV panels create heat as a result of shade and wind speed. Maximum energy harvesting of PV-TEG under non-uniform temperature settings is proposed in this paper using a feed-forward neural network (FFNN) trained by a squirrel search optimization (SQS). TEG systems have several local maxima due to this non-uniform state. MPPT algorithms based on gradients are unlikely to discover actual GMPP in the majority of cases. The unique SQSFFNN is evaluated under non-uniform temperature distribution and variable load and temperature circumstances as a possible answer to this non-linear issue. Certain advances are made in this study by addressing concerns of global maximum power point tracking with non-uniform temperature distribution, low efficiency, higher settling and tracking time, and oscillations. Particle swarm optimization, Cuckoo search optimization (CSA), CSA-FFNN, and grey wolf optimization algorithms are compared to the outcomes. Four experiments are carried out under various meteorological situations. Experiments and MATLAB/SIMULINK are used to validate and prove the results. The experimental results, comparisons with existing techniques, and statistical data show that the suggested SQDFFNN technique achieves a greater performance, distinguishing PV-TEG as a cleaner source of electrical power generation.

Assessment of the integration of Three-Way Catalytic converter and Thermoelectric Generator

Thermoelectric Generator (TEG) in automobiles is a promising way to recover the exhaust heat, and can effectively increase energy utilization. The integration of a Three-Way Catalytic converter (TWC) and TEG can improve the performance by using the heat generated during catalytic operation but still has poor compatibility. Therefore, it is essential that how to improve the compatibility between TWC and TEG. This paper proposed a new method of the coupled carrier of the TWC to enhance the catalytic efficiency and increase the output of TEG. The new TEG was tested under steady and transient conditions. The results showed that the temperature uniformity of TEG is improved. The maximum output power of TEG is increased when TWC with the coupled carrier is working stably. The new TEG with coupled TWC carrier has the highest conversion efficiency for CO, NO, and H2 gases. Under the steady and transient conditions, reaction energy is transferred to the hot side of TEG and the performance of the one-sixth TEG output power can be increased to 306.2W by using the appropriate coupled carrier. Theoretically, this research provides the basis for further study.

Design of Switched-Inductor Charging Regulator for Resistive On-Chip Thermoelectric Generators

On-chip thermoelectric generators (TEGs), unlike bulky off-chip TEGs, are easy to integrate and tiny. A CMOS switched-inductor charging regulator (SLCR) both harvests TEG power & draws battery power to supply Internet-of-Things (IoT) wireless microsensors. However, on-chip TEGs output millivolts, carry <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{M}\boldsymbol{\Omega }$ </tex-math></inline-formula> source resistance R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> , and produce nW power, which demand SLCR to boost low voltage, manage leakage, & maintain high efficiency. Design of such CMOS SLCR power stage often needs prolonged exhaustive tweaking & trial-and-error process. To tackle these challenges, this brief proposes a fundamental theory on the design of nW CMOS SLCR for low-voltage high-R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</sub> applications. With closed-form equations, this theory predicts the optimal power switch, optimal inductor, and optimal current profile, such that SLCR can harvest from the lowest voltage with highest efficiency. This brief provides experimental results with a 180-nm CMOS SLCR power stage prototype. With the theory, an optimal CMOS SLCR power stage can be designed with closed-form equations, without extensive trial-and-error efforts.

Study of the performance of thermoelectric generator for waste heat recovery from chimney: impact of nanofluid-microchannel cooling system.

A huge number of chimneys all over the world utilized in many industrial applications and applications like restaurants, homes, etc. contribute badly on the global warming and climate change due to their waste heat. So, in this paper, the performance of thermoelectric generator (TEG) cooled by microchannel heat spreader having nanofluid and used for waste heat recovery from vertical chimney is investigated. Using heat spreader with microchannel cooling system increases the output TEG power compared to natural convection cooling system. In this paper, the impact of microchannel sizes, using nanofluid and heat spreader with different sizes on the TEG performance and cooling, is considered. Three-dimensional mathematical models including TEG, microchannel, nanofluid, and heat spreader are presented and solved by Ansys Fluent software utilizing user-defined memory, user-defined function, and user-defined scalar. All TEG effects (Joule, Seebeck, and Thomson) are considered in TEG model. Results indicate that TEG power rises with increasing the heat spreader and microchannel sizes together. Increasing microchannel and heat spreader sizes four times of TEG size raises the TEG output power by 10%. This also achieves the maximum cooling system efficiency of 88.9% and the maximum net output power. Microchannel heat spreader cooling system raises the system (TEG power-pumping power) net power by 125.2% compared to the normal channel and decreases the required cooling fluid flow rate. Utilizing copper-water and Al2O3-water nanofluids rises maximally the TEG output power by 14% and 4%, respectively; however, it increases the pumping power. Moreover, using nanofluids increases the net output power at low Reynolds number and decreases it at higher Reynolds number.

A Fully Integrated Power Converter for Thermoelectric Energy Harvesting With 81% Peak Efficiency and 6.4-mV Minimum Input Voltage

This letter introduces a fully integrated inductive power converter for thermal energy harvesting using the thermoelectric generator (TEG). With a three-step self-start block, the power converter can cold-start from 83&#x00A0;mV. After self-start, the minimum input voltage to sustain the power converter operation is only 6.4&#x00A0;mV. An integrated maximum power point tracking block keeps impedance matching at the TEG output. A novel low-power zero-current switching block realizes accurate switching with little overhead. The proposed power converter is implemented in a 55-nm CMOS process and achieves&#x00A0;81&#x0025; peak end-to-end efficiency.