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In this work, a novel quad-band rectifier circuit is introduced for RF energy harvesting and Internet of Things (IoT) applications. The proposed rectifier operates in the Wi-Fi frequency band and can supply low-power sensors and systems used in IoT services. The circuit operates at 2.4 , 3.5 , 5, and 5.8 GHz. The proposed RF-to-DC rectifier is designed based on Delon theory and Greinacher topology on an RT/Duroid 5880 substrate. The results show that our proposed circuit can harvest RF energy from the environment, providing maximum power conversion efficiency (PCE) greater than 81% when the output load is 0.511 kΩ and the input power is 12 dBm. In this work, we provide a comprehensive design framework for an affordable RF-to-DC rectifier. Our circuit performs better than similar designs in the literature. This rectifier could be integrated into an IoT node to harvest RF energy, thereby proving a green energy source. The IoT node can operate at various frequencies. [ABSTRACT FROM AUTHOR]

Wireless Power Transfer (WPT) can effectively solve the problem of autonomous power supply for low-power devices. Rectifier is the key component in WPT technology. In this paper, a novel impedance matching network for the broadband rectifier is proposed. This impedance matching network compensates for the diode impedance and reduces its impedance change when the frequency or input power changes. The passive boosting mechanism utilizing coupled transmission lines (CTLs) improves the power conversion efficiency (PCE) of the diode in the low power region. The structure is especially optimized for low-power device applications. For validation, a broadband rectifier operating at 1.9–3 GHz is fabricated and measured. The structure fabricated on the Rogers 4003 substrate with a thickness of 1.508 mm and the diode is HSMS2860. The DC voltage V o u t on the load ( R L = 1300 Ω) was measured. The results show that at 0 dBm, the PCE keeps more than 60% at 1.98–3 GHz. The peak PCE of 79.6% is obtained at 4 dBm. The compact size of the broadband rectifier is 19 mm × 21 mm. This broadband rectifier for low input power ranges can be applied to WPT technology. [ABSTRACT FROM AUTHOR]

In this paper, a complete analysis of an LLC resonant converter with a customized rectifier structure is presented. The converter is intended for wide, low-input, high-output voltage DC bus applications. The performance of the converter is assessed using comprehensive time-domain and fundamental harmonic approximation (FHA), which demonstrates its capacity to operate across an ample range of voltages by precisely adjusting the rectifier structure. The converter's capability is illustrated by deriving and discussing detailed mode operation, steady-state analysis, and DC gain equations. In order to verify the theoretical analysis, a prototype with a power output of 250 watts is constructed and subjected to testing. The results of the testing demonstrate that the converter is both feasible and effective. The experimental findings illustrate its capacity to manage vast voltage ranges while upholding high efficiency. In addition, the converter utilizes a frequency switching modulation (FSM) to connect with a photovoltaic (PV) panel and control the high output voltage. This demonstrates its adaptability in renewable energy applications. The validation is in accordance with theoretical predictions, demonstrating the converter's high-efficiency performance and versatility. [ABSTRACT FROM AUTHOR]

The paper is devoted to the study of the characteristics and operating modes of a brushless magneto-electric tachogenerator, which is implemented on the basis of a traditional radial electric machine with a slotless stator and permanent magnets on the rotor. Options for generating an DC output signal using diode and transistor rectifiers have been studied. The dependences of the average value of the output signal, the slope of the output signal, the coefficient of deviation of the characteristic from the specified value and the pulsation coefficient were obtained depending on the rotation speed of the rotor shaft. The influence of the capacitance of the filter capacitor on the magnitude of the output signal ripple amplitude has been studied. Ref. 13, fig. 9, table.

This study introduces a novel uninterruptible power supply (UPS) configuration that integrates active power filter (APF) capabilities within a single-phase matrix converter (SPMC) framework. Power disruptions, particularly affecting critical loads, can lead to substantial economic damages. Historically, conventional UPS systems utilized dual separate converters to function as a rectifier and an inverter, without incorporating any power factor correction (PFC) mechanisms. Such configurations suffered from diminished power density, compromised reliability, and spatial limitations. To address these issues, this research proposes an enhanced UPS design that incorporates APF features into the SPMC. The focus of this investigation is on the efficiency of alternating current (AC) to direct current (DC) conversion and the reverse process utilizing this advanced UPS model. The SPMC is selected to supplant the rectifier and inverter units traditionally employed in UPS architectures. A novel integrated switching strategy is formulated to facilitate the operation of the UPS in either rectifier (charging) or inverter (discharging) modes, contingent upon the operational state. The performance and efficacy of the devised circuit design and switching technique are substantiated through simulations conducted in MATLAB/Simulink 2019 and empirical evaluations using a test rig. The findings demonstrate that the voltage generated is sinusoidal and synchronized with the supply current, thereby minimizing the total harmonic distortion (THD) and enhancing both the power factor and the transition efficiency of the UPS system between its charging and discharging states. [ABSTRACT FROM AUTHOR]

In this paper, a CGH40010F GaN-based wideband RF rectifier with high rectification efficiency is presented. A novel continuous class-EFJ-mode rectifier is constructed by combining a continuous class-J-mode rectifier and class-EF-mode rectifier under specific impedance conditions. This novel continuous class-EFJ-mode rectifier has high rectification efficiency and wide bandwidth at the same time. For validation, a wideband high-efficiency class-EFJ-mode rectifier functioning within the 2.0–3.0 GHz range is designed, fabricated, and measured. The measurements indicate that, with an input power of 40 dBm and a resistance of 72 Ω on the dc load, the implemented rectifier sustains a rectification efficiency exceeding 60% across its entire operational frequency band. Meanwhile, the dimensions of the circuits are only 3 cm × 3.1 cm. [ABSTRACT FROM AUTHOR]

A metasurface array for electromagnetic (EM) energy harvesting for Wi-Fi bands is presented in this paper; the metasurface array consists of a metasurface unit, a rectifier, and a load resistor. Each row of unit cells in the array is interconnected to form an energy transfer channel, which enables the transfer and concentration of incident power. Furthermore, at the terminal of the channel, a single series diode rectifier circuit and a load resistor are integrated in a coplanar manner. It is used to rectify the energy in Wi-Fi bands and enables DC energy harvesting across the load. Finally, a 5 × 7 prototype of the metasurface array is fabricated and measured for the verification of the rationality of the design. Testing in an anechoic chamber shows that the prototype achieves a 72% RF-DC efficiency at 5.9 GHz when the available incident power is about 7 dBm. [ABSTRACT FROM AUTHOR]

Rectifier plays a pivotal role in wireless power transfer systems. While numerous studies have concentrated on enhancing efficiency and bandwidth at specific high-power levels, practical scenarios often involve unpredictable power inputs. Consequently, a distinct need arises for a rectifier that demonstrates superior efficiency across a broad range of input power levels. This paper introduces a high-power RF-to-DC rectifier designed for WPT applications, featuring an ultrawide dynamic range of input power. The rectification process leverages a GaN (gallium nitride) high electron mobility transistor (HEMT) to efficiently handle high power levels up to 12.6 W. The matching circuit was designed to ensure that the rectifier will operate in class-F mode. A Schottky diode is incorporated into the design for relatively lower-power rectification. Seamless switching between the rectification modes of the two circuits is accomplished through the integration of a circulator. The proposed rectifier exhibits a 27.5 dB dynamic range, achieving an efficiency exceeding 55% at 2.4 GHz. Substantial improvement in power handling and dynamic range over traditional rectifiers is demonstrated. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive review of the design and implementation methods of low-power piezoelectric energy harvesting circuits, which in the last few years have gained an extremely large range of applications like the power sources of wearable electronic devices, such as biometrical sensors. Before examining the electronic circuitries of the self-supplied power devices, an overview of the structure, equivalent electrical circuits, and basic parameters of the piezoelectric generators and MEMSs as energy harvesting elements is presented. The structure of energy storage elements (parallel-plate capacitors and thin-film supercapacitors), suitable for this type of application, is also presented. The description of these components from an electrical point of view allows them to be easily workable when connected to the various power conversion electronic circuits. Based on an overview of the structure and the principles of operation, as well as some analytical expressions for energy efficiency evaluation, a comprehensive comparative analysis is presented. Depending on the advantages and disadvantages of the known circuit configurations, the basic electrical and design parameters are systematized in tabular form. Practical realizations of piezoelectric power conversion circuits are also presented in graphic form, ensuring the optimal value of energy efficiency and compactness in the construction of the devices. [ABSTRACT FROM AUTHOR]

This article introduces an isolated three-phase six-pulse rectifier using a solid-state transformer. The line frequency utility grid voltage is modulated by a frequency boost converter. This converter exists two parts. The first part is the rectifier section, and the second one is the inverter section. Then after, three-phase diode rectifier is powered by the medium frequency transformer 2 kHz to shrink the transformer size upto 20% or even 10% depensing to the frequency operating range for silicon steel core materials. The aim of this study is to shrink the occupied size of the rectifier using a higher frequency transformer. The study realizes that the grid line current has the same frequency contents as a regular three phase rectifier. In other words, the presented idea results in smaller weight and size while sustaining the performance of input current total harmonic distortion THD=31%. High power density power electronics converter would be extremely valuable for applications such as electric vehicle railways and aircraft. The proposed approach is reliable and easy to use. The solid-state transformer contributes to isolating and improving the overall converter's power density. Simulation results for the 16 kW converter were verified using MATLAB Simulink. [ABSTRACT FROM AUTHOR]

This paper presents a novel adaptive reconfigurable rectifier architecture for radio frequency energy harvesting (RFEH); in addition, a new metric for high-efficiency dynamic range (DR) is proposed. The presented rectifier architecture is based on a double-sided diode-feedback cross-coupled differential-drive rectifier (CCDR) structure incorporating self-body bias for reconfigurable operation. An adaptive structure based on a Schmitt trigger is proposed to adaptively switch the rectifier connection without auxiliary voltage (Vaux), with two rectifier stages in parallel at low power and in series at high power. The system is simulated at a 180 nm CMOS process and the results show more than 17 dB DR at 900 MHz, with efficiency higher than 50% at a 100 kΩ load. [ABSTRACT FROM AUTHOR]

A new type of single–conversion–step wide–input–range versatile step–up/down three–voltage–level power–factor correction stage is presented in this manuscript. The rectifier can operate both in continuous–conduction mode and discontinuous–conduction mode. First, the rectifier's principle of operation is described, and then the innovative rectifier is analyzed in continuous and discontinuous–conduction modes. After, an average model for the innovative rectifier is developed. Lastly, the proposed theory is experimentally validated using a multiplier–less dual–control–loop mode at discontinuous–conduction modes. It is shown that although no multiplier is used in the control circuitry, the power factor is near unity. It is revealed that the rectifier can swing the output voltage from 50 V to 900 V while the input voltage is 230 Vrms. Although the rectifier output has a split DC bus with three voltage levels, the required control effort is low, and the output voltage is balanced. The innovative topology suits any standard power–factor correction rectifier application, dual–stage low–voltage power supply, and three–level voltage supplement for low–harmonic inverters. Since the rectifier's output–voltage swing is extremely wide, energy storage systems and electric vehicle batteries are suitable applications. [ABSTRACT FROM AUTHOR]

A wide-speed, ultra-light power generation system is a critical power generation unit structure, often because of its high efficiency and power density. Lightness and reliability are two key design indicators within the system, albeit they could lead to contradictory problems, particularly in systems containing prime movers, batteries, generators, rectifiers, and inverters. Ultra-light generator sets are facing more severe problems and contradictions in designing in terms of matching, coordinating, and stabilizing the components in the systems. This paper describes the system design of a low-cost and high-reliability microgenerator set: a gasoline engine, three-phase permanent magnet synchronous generator, rectifier, and inverter. Moreover, the matching relationship between the four parts and the design effect of each part of the power generation system was analyzed, simulated, and tested to verify the effectiveness and feasibility of the so-designed system. [ABSTRACT FROM AUTHOR]

Multiple parameter environment monitoring via wireless Internet of Thing sensors is growing rapidly, thanks to low power techniques of the node. More importantly, the ever more complex and highly efficient energy harvesting systems enable long-term continuous monitoring in inaccessible environments without needing to change the battery. This paper reviews existing energy harvesting modalities, including photovoltaic, piezoelectric, pyroelectric, electromagnetic, and vibration, together with circuit techniques of interfacing power management circuits for energy harvesters. Moreover, techniques used to interface with multiple mode energy harvesters to obtain a stable output power with optimal power efficiency are discussed as an emerging direction. The state-of-the-art energy harvesting systems together with future development trends are provided.

In this work, a 2.4 GHz fully woven textile-integrated circularly polarized rectenna intended for wireless power transfer applications is presented. A rectangular patch with truncated corners is used as the radiating element. It is fed through a T-match structure, which allows the control of the input impedance without requiring any additional impedance-matching network. A single-diode rectifier topology was considered to simplify the entire structure and to facilitate its integration with the antenna. The rectifier and the antenna are optimized together through a co-simulation strategy, in which the input impedance of the antenna is adjusted to match the input impedance of the rectifier, ensuring maximum power transfer between them. At the implementation stage, the rectifier is first mounted on a carrier thread, which is then incorporated into the woven structure. This approach, in combination with the chosen antenna feeding technique, which requires no additional elements for impedance matching purposes, provides a high degree of integration between the antenna and the rectifier. The rectenna was experimentally characterized, providing a 45% overall efficiency under realistic working conditions.

This review explores the various strategies used to widen the input power (P $_{\mathrm {IN}}$ ) dynamic range of an RF-DC rectifier and analyzes the recent developments reported in the literature. This development is insightful as the PIN dynamic range is crucial for systems adopting wireless power transfer (WPT) or wireless energy harvesting (EH) for both near- and far-field applications to mitigate the reliance on the battery as its primary power source. However, the RF-DC rectifier exhibits non-linear characteristics, resulting in a narrow PIN band for reasonable power conversion efficiency (PCE). The different strategies reported in the literature are discussed and classified into three main concepts: reconfigurable, multi-path, and self-biased rectifiers. Despite having different design constraints and considerations during the inception of the reported work in the literature, this article analyzes and provides the general development trend, merits, and demerits.

This study introduces a highly efficient harmonic reflection (HR) rectenna designed for precise wireless power transfer (WPT) antenna alignment. The proposed HR rectenna not only converts RF signals to DC power but also transmits a second-harmonic signal to determine the beam alignment between the device and transmitter in diverse environments, including free space and within a medium such as the human body. The proposed rectenna integrates a dual-band slot patch antenna and a HR rectifier. The HR rectifier is configured using a matched voltage doubler and independent second-harmonic impedance control network (ISHICN). To reduce the complexity of the dual-band matching network and mitigate the coupling between the fundamental and harmonic impedances of the HR rectifier, an independent matching technique is applied to a matched voltage doubler and ISHICN, to ensure matching at both the fundamental and harmonic frequencies. Measurement results of the proposed HR rectifier demonstrate impressive performance metrics, including a peak power conversion efficiency (PCE) of 71.6 % at 28 dBm of input power, as well as a peak conversion gain (CG) of -10.4 dB at 8.4 dBm of input power. Notably, the frequency range for PCE >50 % and CG $\gt -22$ dB spans over 0.8 GHz. The antenna adopts a microstrip-fed slot patch design for wide beamwidth at 2.45 GHz and 4.9 GHz, achieving peak gains of 4.9 dBi and 3.8 dBi, respectively. The HR rectenna is integrated with a dual-band microstrip-fed slot patch antenna with sized 60 mm $\times 72.5$ mm. The implemented rectenna is verified to be an efficient WPT receiver through an antenna beam alignment experiment in free space and minced-pork environment.

This paper presents a wireless power conversion system designed for biomedical implants, with integrated automatic resonance tuning. The automatic tuning mechanism improves power transfer efficiency (PTE) by finely tuning the resonant frequency of the power link and maximizing the rectified voltage. This adjustment ensures robust and reliable remote powering, even in the face of environmental changes and process variations, while also minimizing tissue exposure to power. On-chip switched array capacitors are connected in parallel with the resonant capacitor, and the system identifies the optimal switched capacitor combination for the highest rectified voltage by iterating over each of them. The proposed system is implemented and fabricated in standard 180nm CMOS technology, with a total area of 0.339 mm2, and its operation is verified. The measurement results demonstrate that this system provides tolerance up to mismatches equivalent to 75 pF capacitance variation in LC tank, ±15% LC variation in this design. The system offers a PTE enhancement from 9.1% to 30.2% in case of high LC variation, and the tuning control consumes 154.7 $\mu \text{W}$ of power during resonance tuning. Moreover, the power conversion chain delivers an optimized rectified voltage along with a regulated voltage of 1.8 V.

The use of RF harvesting as a power source for low-power systems, such as wearables, wireless sensor nodes, and Internet of Things, has gained attention. The primary obstacle to develop an effective RF-DC system has been the RF rectifier. The method most frequently employed in the design of RF-DC converters is called Cross-Coupled Differential Drive (CCDD). To enhance the DC output voltage, multistage systems are typically employed. In these designs, DC output will reach saturation as the number of stages rises. This is because the NMOS threshold voltage will rise if the bulk of the NMOS is connected to the lowest potential. An alternative is to employ the twin-well CMOS process, which is more expensive than the regular n-well process. A novel CMOS RF-DC converter is presented in this brief. The design is hybrid in the sense the first stage is designed using a standard CCDD, while the second and subsequent stages are designed exclusively with PMOS transistors. This allows the use of the n-well process during fabrication. With CADENCE Virtuoso in $0.18~\mu \text{m}$ TSMC CMOS technology, the suggested design’s functionality is verified. The design is functional and achieves 45% efficiency and a power dynamic range of 23dB for power conversion efficiency (PCE) >20%, according to simulation findings.

In this work, a novel quad-band rectifier circuit is introduced for RF energy harvesting and Internet of Things (IoT) applications. The proposed rectifier operates in the Wi-Fi frequency band and can supply low-power sensors and systems used in IoT services. The circuit operates at 2.4, 3.5, 5, and 5.8 GHz. The proposed RF-to-DC rectifier is designed based on Delon theory and Greinacher topology on an RT/Duroid 5880 substrate. The results show that our proposed circuit can harvest RF energy from the environment, providing maximum power conversion efficiency (PCE) greater than 81% when the output load is 0.511 kΩ and the input power is 12 dBm. In this work, we provide a comprehensive design framework for an affordable RF-to-DC rectifier. Our circuit performs better than similar designs in the literature. This rectifier could be integrated into an IoT node to harvest RF energy, thereby proving a green energy source. The IoT node can operate at various frequencies.

This work designs and implements a single-stage rectifier-based RF energy harvesting device. This device integrates a receiving antenna and a rectifying circuit to convert ambient electromagnetic energy into useful DC power efficiently. The rectenna is carefully engineered with an optimal matching circuit, achieving high efficiency with a return loss of less than −10 dB. The design uses a practical model of the Schottky diode, where both RF and DC characteristics are derived through extensive experimental measurements. The results from both experiments and simulations confirm the effectiveness of the design, showing its proficiency in efficient RF energy harvesting under low-power conditions. The antenna produced operates in the wifi band with a gain close to 4 dBi and a bandwidth of 100 MHz. With a load resistance of 1600 Ω, the proposed device achieves an impressive RF-to-DC conversion efficiency of approximately 52% at a low incident power of −5 dBm. These findings highlight the potential and reliability of rectenna systems for practical and efficient RF energy harvesting applications. The study significantly contributes to our understanding of rectenna-based energy harvesting, providing valuable insights for future design considerations and applications in low-power RF systems.

A metasurface array for electromagnetic (EM) energy harvesting for Wi-Fi bands is presented in this paper; the metasurface array consists of a metasurface unit, a rectifier, and a load resistor. Each row of unit cells in the array is interconnected to form an energy transfer channel, which enables the transfer and concentration of incident power. Furthermore, at the terminal of the channel, a single series diode rectifier circuit and a load resistor are integrated in a coplanar manner. It is used to rectify the energy in Wi-Fi bands and enables DC energy harvesting across the load. Finally, a 5 × 7 prototype of the metasurface array is fabricated and measured for the verification of the rationality of the design. Testing in an anechoic chamber shows that the prototype achieves a 72% RF-DC efficiency at 5.9 GHz when the available incident power is about 7 dBm.

This study introduces a novel uninterruptible power supply (UPS) configuration that integrates active power filter (APF) capabilities within a single-phase matrix converter (SPMC) framework. Power disruptions, particularly affecting critical loads, can lead to substantial economic damages. Historically, conventional UPS systems utilized dual separate converters to function as a rectifier and an inverter, without incorporating any power factor correction (PFC) mechanisms. Such configurations suffered from diminished power density, compromised reliability, and spatial limitations. To address these issues, this research proposes an enhanced UPS design that incorporates APF features into the SPMC. The focus of this investigation is on the efficiency of alternating current (AC) to direct current (DC) conversion and the reverse process utilizing this advanced UPS model. The SPMC is selected to supplant the rectifier and inverter units traditionally employed in UPS architectures. A novel integrated switching strategy is formulated to facilitate the operation of the UPS in either rectifier (charging) or inverter (discharging) modes, contingent upon the operational state. The performance and efficacy of the devised circuit design and switching technique are substantiated through simulations conducted in MATLAB/Simulink 2019 and empirical evaluations using a test rig. The findings demonstrate that the voltage generated is sinusoidal and synchronized with the supply current, thereby minimizing the total harmonic distortion (THD) and enhancing both the power factor and the transition efficiency of the UPS system between its charging and discharging states.

Rectifier plays a pivotal role in wireless power transfer systems. While numerous studies have concentrated on enhancing efficiency and bandwidth at specific high-power levels, practical scenarios often involve unpredictable power inputs. Consequently, a distinct need arises for a rectifier that demonstrates superior efficiency across a broad range of input power levels. This paper introduces a high-power RF-to-DC rectifier designed for WPT applications, featuring an ultrawide dynamic range of input power. The rectification process leverages a GaN (gallium nitride) high electron mobility transistor (HEMT) to efficiently handle high power levels up to 12.6 W. The matching circuit was designed to ensure that the rectifier will operate in class-F mode. A Schottky diode is incorporated into the design for relatively lower-power rectification. Seamless switching between the rectification modes of the two circuits is accomplished through the integration of a circulator. The proposed rectifier exhibits a 27.5 dB dynamic range, achieving an efficiency exceeding 55% at 2.4 GHz. Substantial improvement in power handling and dynamic range over traditional rectifiers is demonstrated.

The use of radio frequency (RF) energy for wireless power transfer (WPT) has gained significant attention in recent years due to its potential for powering electronic devices without the need for wires or batteries. A key component of RF-based WPT systems is the rectenna, which converts RF energy into usable DC power. This article provides an overview of recent developments, opportunities, and challenges in the design of 2.4 GHz rectennas for RF-based WPT applications. We have searched major online libraries extensively for studies regarding the 2.4 GHz rectenna. As a result, 35 high-quality studies published between 2010 and 2023 were gathered. In the discussion section, we begin by presenting the basic principles of rectenna design and the key parameters that affect its performance, such as the antenna characteristics, rectifier capabilities, and nonlinearity properties of the rectifier. We then highlighted recent advancements in rectenna design, including novel approaches for improving efficiency and power transfer capability, such as the involvement of hybrid solar cell-rectenna structures, transistor-based rectifiers, and bridge rectifiers. Finally, the article concludes by identifying future opportunities, research directions, and open challenges in the design and optimization of rectennas for RF-based WPT, including the development of compact, low-cost, and high-performance rectennas for a wide range of applications. Overall, this article provides a comprehensive overview of the state-of-the-art of 2.4 GHz rectenna design for RF-based WPT and highlights the exciting opportunities and challenges for this rapidly growing field.

This paper presents the results obtained in the design, implementation and testing of a bidirectional CSI (Current source inverter) converter, which is capable of delivering and taking power from the grid to charge a 72 V battery bank. This converter is sized within a photovoltaic solar system designed for homes in the city of Tunja, based on real data to estimate the average consumption of a typical home in the "Cooservicios" sector of the city, proposing two ways of working the system, one to obtain a constant average consumption and another in which the total consumption is zero. The converter is implemented with all its components, digital and power stages, using for the control a TMS 320F28377S microcontroller from C2000 family, of Texas Instruments. The implementation meets specifications of: bidirectional operation as an inverter and as a rectifier, output power of 469 W, efficiency around 80%, highlighting the considerably high value required for the input inductance of 0.3 H that causes losses in the system.

This paper proposes a self-supplied power management system to efficiently rectify and regulate the AC voltage received from wireless power transmission techniques to power or recharge biomedical devices. The proposed power management system comprises three integrated functional units, namely, a fully cross-coupled rectifier, a self-biased reference voltage, and a capacitor-less low-dropout regulator (LDO). To reduce the current complexity of designing capacitor-less LDOs, a new architecture based on a pair of diode-connected transistors at the load of the LDO is devised which alleviates the need for a large load capacitor. The proposed power management system is implemented in a 65-nm CMOS process with an active chip area of 0.0810 mm2. Experimental results indicate that this system is capable of rectifying an AC signal up to 5 V at a frequency of 6.78 MHz. This rectified signal is then regulated to a fixed DC voltage of 1.75 V, while the load current can vary between 0 and 75 mA, with a maximum voltage dropout of 170 mV. Advantageously, the proposed power management system is significantly robust to temperature, as a 55 °C change in ambient temperature leads to only a 9% degradation in its overall performance. Furthermore, the ability of the power management system to drive low-power consumer electronics is demonstrated, and its superiority is evidenced by a performance comparison with the latest integrated power management systems presented in the literature. [ABSTRACT FROM AUTHOR]

A hypoglossal nerve stimulator (HGNS) is an invasive device that is used to treat obstructive sleep apnea (OSA) through electrical stimulation. The conventional implantable HGNS device consists of a stimuli generator, a breathing sensor, and electrodes connected to the hypoglossal nerve via leads. However, this implant is bulky and causes significant trauma. In this paper, we propose a minimally invasive HGNS based on an electrocardiogram (ECG) sensor and wireless power transfer (WPT), consisting of a wearable breathing monitor and an implantable stimulator. The breathing external monitor utilizes an ECG sensor to identify abnormal breathing patterns associated with OSA with 88.68% accuracy, achieved through the utilization of a convolutional neural network (CNN) algorithm. With a skin thickness of 5 mm and a receiving coil diameter of 9 mm, the power conversion efficiency was measured as 31.8%. The implantable device, on the other hand, is composed of a front-end CMOS power management module (PMM), a binary-phase-shift-keying (BPSK)-based data demodulator, and a bipolar biphasic current stimuli generator. The PMM, with a silicon area of 0.06 mm 2 (excluding PADs), demonstrated a power conversion efficiency of 77.5% when operating at a receiving frequency of 2 MHz. Furthermore, it offers three-voltage options (1.2 V, 1.8 V, and 3.1 V). Within the data receiver component, a low-power BPSK demodulator was ingeniously incorporated, consuming only 42 μ W when supplied with a voltage of 0.7 V. The performance was achieved through the implementation of the self-biased phase-locked-loop (PLL) technique. The stimuli generator delivers biphasic constant currents, providing a 5 bit programmable range spanning from 0 to 2.4 mA. The functionality of the proposed ECG- and WPT-based HGNS was validated, representing a highly promising solution for the effective management of OSA, all while minimizing the trauma and space requirements. [ABSTRACT FROM AUTHOR]

This paper presents the results obtained in the design, implementation and testing of a bidirectional CSI (Current source inverter) converter, which is capable of delivering and taking power from the grid to charge a 72 V battery bank. This converter is sized within a photovoltaic solar system designed for homes in the city of Tunja, based on real data to estimate the average consumption of a typical home in the "Cooservicios" sector of the city, proposing two ways of working the system, one to obtain a constant average consumption and another in which the total consumption is zero. The converter is implemented with all its components, digital and power stages, using for the control a TMS 320F28377S microcontroller from C2000 family, of Texas Instruments. The implementation meets specifications of: bidirectional operation as an inverter and as a rectifier, output power of 469 W, efficiency around 80%, highlighting the considerably high value required for the input inductance of 0.3 H that causes losses in the system. [ABSTRACT FROM AUTHOR]

This paper presents the deployment of a hybrid energy harvesting system that combines a wireless energy harvesting (EH) system and a 6 V, 170 mA monocrystalline solar energy derived from the Sun's rays. The hybrid energy harvesting (HEH) system comprises the rectifier, the solar cell panel, the charging circuit, and the EM4325 embedded RFID tag. This study aims to design an efficient EH system capable of increasing the read range of an active RFID tag. The proposed approach integrates a meandered line radio frequency identification (RFID) tag with an EM4325 IC chip as the receiver antenna. A halfwave doubler RF rectifier circuit is connected to the antenna using a 50 Ω SMA connector to convert the captured RF waves into usable electrical power. A solar energy charging module equipped with a Maximum Power Point Tracking (MPPT) system, a rechargeable lithium-ion battery, and a DC-DC converter is configured to manage and store the harvested energy efficiently. The UHF tag antenna operates at 919 MHz, achieving a peak gain of 3.54 dB. The proposed rectenna achieves a maximum measured harvested power conversion efficiency (PCE) of 55.14% for an input power (Pin) of 15 dBm at a distance of 5.10 cm, while the solar cell panel realizes 3.92 W of power. Experimental results demonstrate the hybrid harvester system's effectiveness, achieving a PCE of 86.49% at an output voltage (VDC) of 5.35 V. The main advantage of this approach is the creation of a compact hybrid RF and solar EH system by combining the solar cell panel with the antenna, thus enabling multi-functionality. [ABSTRACT FROM AUTHOR]

There is a global trend to reduce emissions from cars through the adoption of other alternatives, such as electric vehicles (EVs). The increasing popularity of EVs has led to a growing demand for electric vehicle chargers. EV chargers are essential for charging the batteries of EVs. Since the EV charger stays connected to the grid for long periods of time to charge the EV battery, it must be able to handle disturbances in the power grid. The goal of this paper is to present an overview of the impact of grid events on EV battery chargers. As well as the impact of grid unbalances on EV chargers, this paper also provides an overview of the impact of grid faults on other, similar power electronics interfaced resources such as PV and energy storage systems. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive review of the design and implementation methods of low-power piezoelectric energy harvesting circuits, which in the last few years have gained an extremely large range of applications like the power sources of wearable electronic devices, such as biometrical sensors. Before examining the electronic circuitries of the self-supplied power devices, an overview of the structure, equivalent electrical circuits, and basic parameters of the piezoelectric generators and MEMSs as energy harvesting elements is presented. The structure of energy storage elements (parallel-plate capacitors and thin-film supercapacitors), suitable for this type of application, is also presented. The description of these components from an electrical point of view allows them to be easily workable when connected to the various power conversion electronic circuits. Based on an overview of the structure and the principles of operation, as well as some analytical expressions for energy efficiency evaluation, a comprehensive comparative analysis is presented. Depending on the advantages and disadvantages of the known circuit configurations, the basic electrical and design parameters are systematized in tabular form. Practical realizations of piezoelectric power conversion circuits are also presented in graphic form, ensuring the optimal value of energy efficiency and compactness in the construction of the devices.

A new type of single–conversion–step wide–input–range versatile step–up/down three–voltage–level power–factor correction stage is presented in this manuscript. The rectifier can operate both in continuous–conduction mode and discontinuous–conduction mode. First, the rectifier’s principle of operation is described, and then the innovative rectifier is analyzed in continuous and discontinuous–conduction modes. After, an average model for the innovative rectifier is developed. Lastly, the proposed theory is experimentally validated using a multiplier–less dual–control–loop mode at discontinuous–conduction modes. It is shown that although no multiplier is used in the control circuitry, the power factor is near unity. It is revealed that the rectifier can swing the output voltage from 50 V to 900 V while the input voltage is 230 Vrms. Although the rectifier output has a split DC bus with three voltage levels, the required control effort is low, and the output voltage is balanced. The innovative topology suits any standard power–factor correction rectifier application, dual–stage low–voltage power supply, and three–level voltage supplement for low–harmonic inverters. Since the rectifier’s output–voltage swing is extremely wide, energy storage systems and electric vehicle batteries are suitable applications.

This work presents the experimental validation of a 40 kW electric vehicle (EV) charger. The proposed system comprises two 20 kW modules connected in parallel at the input and output. Each module has two stages—as a grid converter Vienna Rectifier (VR) was chosen, and as an isolated DC/DC stage, two Series-Resonant Dual-Active-Bridges (SRDABs) in input-series-output-parallel (ISOP) configurations were applied. The AC/DC and DC/DC stages were enclosed in 2U rack standard housing. A bipolar DC-link with ±400 V DC voltage was employed to connect both stages of the charger module while the charger's output is dedicated to serving 800 V batteries. VRs operated at 66 kHz switching frequency and the SRDABs operated at 100 kHz. The converters used in the charger structure were based on silicon carbide (SiC) power devices. The description and parameters of the built hardware prototypes of both—AC/DC and DC/DC—converters are provided. Moreover, the experimental validation of each stage and the whole charging system, including oscilloscope waveforms and power analyzer measurements at nominal power, are included. Such a configuration enables energy conversion with high efficiency without a negative impact on the grid and high-quality grid waveforms. [ABSTRACT FROM AUTHOR]

A comprehensive model for micro-powered piezoelectric generator (PG), analysis of operation, and control of voltage doubler joule thief (VDJT) circuit to find the piezoelectric devices (PD's) optimum functioning points are discussed in the present article. The proposed model demonstrates the power dependence of the PG on mechanical excitation, frequency, and acceleration, as well as outlines the load behaviour for optimal operation. The proposed VDJT circuit integrates the combination of voltage doubler (VD) and joule thief circuit, whereas the VD circuit works in Stage 1 for AC (alternating current)–DC (direct current) conversion, while a joule thief circuit works in Stage 2 for DC–DC conversion. The proposed circuit functions as an efficient power converter, which converts power from AC–DC and boosts the voltage from low to high without employing any additional electronic components and generating duty cycles. The electrical nature of the input (i.e., PD) of a VDJT circuit is in perfect arrangement with the investigated optimisation needs when using the proposed control circuit. The effectiveness of the proposed VDJT circuit is examined in terms of both simulation and experiment, and the results are presented. The proposed circuit's performance was validated with available results of power electronics interfaces in the literature. The proposed circuit's flexibility and controllability can be used for various applications, including mobile battery charging and power harvesting. [ABSTRACT FROM AUTHOR]

Single-loop current sensorless control allows for abolishing of the instantaneous current measurement in the control system using only a single control loop with voltage feedback to stabilise the DC-bus voltage. This approach eliminates current sensors in the control circuit, benefiting from saving space on the printed circuit board and minimising power dissipation in the current measurement circuitry. This paper focuses on the single-loop current sensorless control applied to bidirectional three-phase four-wire three-level NPC MLC by simulation analysis and demonstrates the performance of the proposed current control algorithm in the rectifier and inverter modes and the step response with power direction change and grid-voltage change. In capacitor voltage balancing, an additional controller is applied, which is capable of compensating for the voltage asymmetry caused by adding a 2.5 kOhm resistor in parallel to one of the DC-bus capacitors. Our results demonstrate good performance of the proposed control method both in the inverter and rectifier modes, showing stable current shape in the low power and full power modes with acceptable harmonics content, meeting the requirements of the IEC 61000-3-2 standard for Class A devices. The analysis showed that the proposed control approach is suitable for industrial application. [ABSTRACT FROM AUTHOR]

Optimized vertical heterojunction rectifiers with a diameter of 100 µm, consisting of sputter-deposited p-type NiO forming a p–n junction with thick (10 µm) Ga2O3 drift layers grown by halide vapor phase epitaxy (HVPE) on (001) Sn-doped (1019 cm−3) β-Ga2O3 substrates, exhibited breakdown voltages > 8 kV over large areas (>1 cm2). The key requirements were low drift layer doping concentrations (<1016 cm3), low power during the NiO deposition to avoid interfacial damage at the heterointerface and formation of a guard ring using extension of the NiO beyond the cathode metal contact. Breakdown still occurred at the contact periphery, suggesting that further optimization of the edge termination could produce even larger breakdown voltages. On-state resistances without substrate thinning were <10 mΩ·cm−2, leading to power figure-of-merits > 9 GW·cm−2. The devices showed an almost temperature-independent breakdown to 600 K. These results show the remarkable potential of NiO/Ga2O3 rectifiers for performance beyond the limits of both SiC and GaN. The important points to achieve the excellent performance were: (1) low drift doping concentration, (2) low power during the NiO deposition and (3) formation of a guard ring. [ABSTRACT FROM AUTHOR]

In recent years, wireless power transfer (WPT) has become a widespread method for charging and powering devices, including but not limited to consumer electronics, industrial applications, electric vehicles, medical devices, and sensor nodes. This article provides an overview of the available WPT technologies, focusing on the near-field case, and highlights the main architecture and circuit-level challenges encountered in the implementation of magnetic-based near-field WPT systems while reviewing the proposed solutions in the literature, in order to identify the main research interests as well as the trends for the future.

This paper presents a compact broadband stepped bow-tie antenna for ambient RF energy harvesting (RFEH). The proposed antenna consists of stepped shapes for wide bandwidth, making it possible to investigate ambient RF energy in entire cellular bands. In addition, the antenna is composed of a bow-tie shape to achieve compactness for internet of things (IoT) sensors. We explain the design steps taken to achieve this wide bandwidth, analyzing the surface current distributions with respect to the number of stepped shapes through an EM simulation. In addition, we cut the broadband antenna in half and integrated it with the RFEH circuit for compactness, causing impedance matching to deteriorate. The novel modified bow-tie shaped half antenna improved impedance matching, which is analyzed with the surface current distribution. We found that the proposed antenna has a fractional bandwidth of 125% of $S_{11} < -10$ dB, ranging from 0.85 GHz to 3.66 GHz with a compact dimension of 68 mm $\times107$ mm ( $0.19\,\,\lambda _{0} \times 0.30\,\,\lambda _{0}$ ). With the proposed antenna, we investigated ambient RF energy at several outdoor sites and chose the feasible frequency bands (0.9 GHz and 1.8 GHz). For the bands, the RFEH circuit was designed consisting of a rectifier and power management unit (PMU), and integrated into the proposed antenna. In one site, we experimented and verified the RFEH with the antenna. The broadband and compact antenna in this paper can contribute to implementing the RFEH prototype for the capability to be used as a power source for IoT sensors.

This article aims to contribute for the improvement of low-power Radio Frequency Energy Harvesting (RFEH) designs based on Schottky Barrier Diode (SBD) rectifiers, presenting a study of the relationship between RF-DC Power Conversion Efficiency (PCE) and circuit temperature, which is directly related to the non-linear behavior of the metal-semiconductor junction of SBDs. For this purpose, SPICE diode models were revisited, evaluating the temperature dependence and its effects on forward and reverse conduction modes. The SBDs SMS7621 and SMS7630 temperature dependent characteristics are evaluated according the proposal, and their use is explored through analytical modeling and simulation analyzes of an RFEH system for temperatures ranging from 240 to 360 K. Hence, after an initial formulation of the optimum operation in terms of PCE, two series RF rectifiers are designed based on the mentioned diodes, aiming at an efficient operation over different temperature ranges according to each component optimum PCE, at 300 K for the SMS7630 and over 340 K for the SMS7621. For the SMS7630 prototype, the maximum measured PCE is 25.33% around 293 K, but decreases to 3.65% around 353 K, and for the SMS7621 the measured PCE goes from 11.56% to 16.34% in the same temperature range, considering −20 dBm as Input Power ( $P_{in}$ ) due to the low-power RFEH premise. The results leads to a higher PCE stability for the SMS7621 through the whole analyzed range, despite the overall PCE that is limited by the matching network losses intrinsic to the design.

This paper proposes a radio frequency (RF) rectifier topology for low-power wireless power transmission (WPT) applications in the X band. The rectifier consists of a biased PMOS pair and is matched to the RF signal source impedance using a PCB transmission line (TL) matching network. It is demonstrated that a clever optimization of the bias voltage enables the rectifier to achieve greater sensitivity and efficiency than previous works at X band. The rectifier was designed in a 45 nm silicon-on-insulator (SOI) process and operates at a frequency of 9.64 GHz. It achieves a power conversion efficiency (PCE) of 4% and 46% at power levels of −35 dBm and −10 dBm, respectively.

The electromagnetic processes in a single-phase bridge rectifier with an active load and a capacitive filter during its power supply from a symmetrical inductive-capacitive converter (ICC) made according to the M1 scheme were studied, and a comparison of its quality characteristics with the ICC according to the T1-LCL scheme was carried out. It was established that the M1 scheme has better specific power indicators, however, the use of the ICC bridge structure is impractical without improving its electromagnetic compatibility with the power supply network. Methods of perfecting such an ICC are proposed. Ref. 14, fig. 4, table.

This paper presents a reconfigurable high efficiency, high output voltage, and multiband class-F radio frequency (RF) voltage doubler and two stages voltage doubler rectifiers for energy harvesting applications using RO4003C substrate. The proposed voltage-doubler circuits are suitable for multi-band LTE, IoT, WSN, UHF ISM 900 MHz, GSM 900, energy harvesting, and multi-standard applications. The voltage doubler circuits are implemented using the Schottky diode (HSMS2852). Also, the voltage-doubler circuits are optimized and refabricated to recompense the unwanted parasitic and achieve the required performance. The voltage doubler and two stages voltage doubler rectifiers have a measured efficiency exceeding 40% in the frequency band from 650 MHz to 900 MHz at −10dBm input power and a load resistance of 10kohm, 22kohm, and an output voltage of 1 V at −10dBm input power. The proposed class-F RF voltage doubler achieves maximum efficiency of 72%, saturated output voltage equals 3.5 V, and the efficiency equals 51% at −10dBm input power. On the other hand, the proposed class-F two stages RF voltage doubler has a peak efficiency of 54%, saturated output voltage equals 6.5 V at 4dBm input power, and the efficiency equal 38% at −10dBm input power. Finally, the PCB areas of the proposed voltage-doubler and two stages voltage-doubler equal 2.8cm2and 3.6 cm2, respectively.

Most low-power electronics, such as remote sensors and embedded devices, are powered by batteries. Replacement is expensive when there are hundreds of sensors in remote locations. RF Energy Harvesting can be used to provide an alternative energy source for these types of embedded devices. This study is to analyze the effect of the number of elements of the yagi print antenna array on the efficiency of receiving power at a frequency of 2.4 GHz. The making of this harvesting energy system is aimed at making the energy around us maximally utilized and used as alternative energy by the community. The highest output voltage of the rectifier antenna at a distance of 10 cm from the access point is 216 mV for a single element yagi print antenna, 96 mV for a 2 element yagi print antenna, and 168 mV for a 4 element yagi print antenna. with no load, the number of array elements affects the output voltage of the rectifier in addition to the number of stage voltage multipliers.

With low-power gadgets proliferating, the development of a small, effective rectenna is crucial for wirelessly energizing devices. A simple circular patch with a partial ground plane for RF-energy harvesting at ISM (2.45 GHz) band is proposed in this work. The simulated antenna resonates at 2.45 GHz with an input impedance of 50 Ω and a gain of 2.38 dBi. An L-section matching a circuit with a voltage doubler is proposed to provide excellent RF-to-DC transformation efficiency at low power input. The proposed rectenna is fabricated and the results show that the return loss and realized gain have good characteristics at the ISM band with 52% of RF-to-DC transformation efficiency, with an input of 0 dBm power. The projected rectenna is apt for power-up low sensor nodes in wireless sensor applications. [ABSTRACT FROM AUTHOR]

Miniaturised piezoelectric devices are emerging energy harvesting sources that are appropriate for various implantable and wearable applications. However, these piezoelectric devices exhibit considerable internal resistance due to their internal impedance, which leads to self-start and low-energy conversion failures. This paper describes a dual-stage boost converter circuit by facilitating self-powering features and boosting the low voltage harvested by the piezoelectric devices into dc. The proposed circuit comprises conversion stages of ac-dc and dc-dc in Stages I and II, respectively. In addition, the proposed circuit does not require employing the auxiliary circuits to generate the train pulses by triggering the bidirectional switches to envelop the current being stored in Stage II and kick-start the self-powered circuit for piezoelectric energy harvesting systems. Theoretical assumptions and control strategies were tested and verified with ideal and impedance input sources. The proposed circuit could convert a low voltage of 3 Vac into 19 Vdc. The maximum attained output power by the proposed circuit was 3.61 mW. The outcome depicted that the proposed circuit boosted the low voltage and outperformed the existing literature circuits in terms of output voltage and power. [ABSTRACT FROM AUTHOR]

Active Front-End (AFE) rectifiers have regained momentum as the demand for highpower Electric Vehicle (EV) charging infrastructure increases exponentially. AFE rectifiers have high efficiency and reliability, and they minimize the disturbances that could be generated due to the operation of the EV charging systems by reducing harmonic distortion and operating close to the Unity Power Factor (UPF). The purpose of this review is to present the current state-of-the-art AFE rectifiers used in fast chargers, focusing on the comparison between different AFE topologies and their components, as well as modular AFE solutions. Furthermore, different control strategies of AFE converters are presented and compared. Some of their more widely used control techniques, namely Voltage Oriented Control (VOC), Direct Power Control (DPC), Hysteresis Current Control (HCC), and Model Predictive Control (MPC), have been implemented, and their performance compared. Centralized and distributed control systems are compared for operating parallel AFE rectifiers for modular, fast charging systems. An overview of cooling systems and reliability evaluation tools is also presented. Finally, trends and future outlooks are analyzed. [ABSTRACT FROM AUTHOR]

This paper presents the converter design of a single-phase non-isolated step-down controlled rectifier for power factor improvement and output voltage regulation. The converter consists of a full-bridge diode rectifier and a DC–DC interleaved buck converter of two or more switching cells that has an LC filter in its input. It is proposed that the interleaved switching cells operate in discontinuous conduction mode and the current through the input LC filter be continuous, avoiding switching frequency components to be injected into the grid. The controller, which has a simple structure and a small number of sensors, allows the system to achieve a high power factor. It also regulates the output voltage to a constant reference. An experimental prototype is built and tested to validate the analysis and proposed design. The closed-loop converter is evaluated both in a steady state and in transient conditions. At steady state, the converter achieves a power factor above 0.9 with a maximum of 45.4% THD at 110.1W. The main contributions of this paper are guidelines for the design of the converter, open-loop analysis, and converter control. [ABSTRACT FROM AUTHOR]