Full-bridge Rectifier Research Articles

A Fully Energy-Autonomous Temperature-to-Time Converter Powered by a Triboelectric Energy Harvester for Biomedical Applications

This article presents a fully energy-autonomous temperature-to-time converter (TTC), entirely powered up by a triboelectric nanogenerator (TENG) for biomedical applications. Existing sensing systems either consume too much power to be sustained by energy harvesting or have poor accuracy. Also, the harvesting of low-frequency energy input has been challenging due to high reverse leakage of a rectifier. The proposed dynamic leakage suppression full-bridge rectifier (DLS-FBR) reduces the reverse leakage current by more than 1000 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> , enabling harvesting from sparse and sporadic energy sources; this enables the TTC to function with a TENG as the sole power source operating at <1-Hz human motion. Upon harvesting 0.6 V in the storage capacitor, the power management unit (PMU) activates the low-power TTC, which performs one-shot conversion of temperature to pulsewidth. Designed for biomedical applications, the TTC enables a temperature measurement range from 15 °C to 45 °C. The energy-autonomous TTC is fabricated in 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> 1P6M CMOS technology, consuming 0.14 pJ/conversion with 0.014-ms conversion time.

A comprehensive design analysis of a cost-effective WPT system with a class-E power amplifier and a T-matching network

Magnetically-coupled resonant wireless power transfer systems (WPTs) operating in the megahertz range is well-suited for mid-range transmission of moderate power levels. The class-E power amplifier (PA) is attractive for the MHz WPT applications due to the high-efficiency and soft-switching properties. However, since the output power and the efficiency of the class-E PA strongly depends on the output load, any change in the mutual inductance of coupling coils, which leads to the PA load variation, results in a dramatic loss in the overall performance of WPT system. This paper provides a comprehensive design analysis to analytically and numerically mimic the PA behavior to conveniently adapt any variation of the input impedance of the coupled coils to the PA optimum load using a T-type matching network. An equivalent circuit analysis followed by the design theory for the class-E PA, coupled coils, and the T-network has been presented. For validation purposes, the class-E PA implemented by the cost-effective IRF640 MOSFET was first fabricated and its performance was measured for different load values. The PA efficiency and output power was measured as high as 96.7% and 25.8 W, respectively, for the optimum load value of 9 Ω, which was closely predicted from the theory. A 1 MHz WPT system was then built for the operating range up to 27 cm, showcasing its behavior in presence and absence of the proposed T-type matching circuits at two arbitrary 10 cm and 25 cm distances between the coupling coils; the input impedance of the WPT system for those separation distances were 4 Ω and 0.2 Ω, respectively. Results demonstrate power transfer efficiencies of 88% and 15% at distances of 10 cm and 25 cm with the T-network, respectively, improved by 33% and 12% to the non-matching state, respectively. The overall DC output power achieved using a full-bridge rectifier are 21.9 W and 6.8 W at 10 cm and 25 cm, respectively.

A Fully Integrated AC-DC Converter in 1 V CMOS for Electrostatic Vibration Energy Transducer with an Open Circuit Voltage of 10 V

This paper proposes an AC-DC converter for electrostatic vibration energy harvesting. The converter is composed of a CMOS full bridge rectifier and a CMOS shunt regulator. Even with 1 V CMOS, the open circuit voltage of the energy transducer can be as high as 10 V and beyond. Bandgap reference (BGR) inputs a regulated voltage, which is controlled by the output voltage of the BGR. Built-in power-on reset is introduced, which can minimize the silicon area and power to function normally found upon start-up. The AC-DC converter was fabricated with a 65 nm low-Vt 1 V CMOS with 0.081 mm2. 1 V regulation was measured successfully at 20–70 °C with a power conversion efficiency of 43%.

Analyzing the Effect of Parasitic Capacitance in a Full-Bridge Class-D Current Source Rectifier on a High Step-Up Push–Pull Multiresonant Converter

This paper presents an analysis on the effect of a parasitic capacitance full-bridge class-D current source rectifier (FB-CDCSR) on a high step-up push–pull multiresonant converter (HSPPMRC). The proposed converter can provide high voltage for a 12 VDC battery using an isolated transformer and an FB-CDCSR. The main switches of the push–pull and diode full-bridge rectifier can be operated under a zero-current switching condition (ZCS). The advantages of this technique are that it uses a leakage inductance to achieve the ZCS for the power switch, and the leakage inductance and parasitic junction capacitance are used to design the secondary side of the resonant circuit. A prototype HSPPMRC was built and operated at 200 kHz fixed switching frequency, 340 VDC output voltage, and 250 W output power. In addition, the efficiency is equal to 96% at maximum load. Analysis of the effect of the parasitic junction capacitance on the full-bridge rectifier indicates that it has a significant impact on the operating point of the resonant tank and voltage. The proposed circuit design was verified via experimental results, which were found to be in agreement with the theoretical analysis.

Enhancing output power of rotational electret energy harvester by synchronized switch harvesting on inductor

A nonlinear interface circuit, known as synchronized switch harvesting on inductor (SSHI), for in-plane rotational electret kinetic energy harvesters (EHs) was developed. An explicit generator model is derived to verify the applicability of SSHI, which was originally proposed for the piezoelectric EH, on an in-plane electret EH. Experimentally, 505 μW was harvested with SSHI at a rectified voltage of 142 V for an in-plane rotational electret EH rotating at 1 rps, which is 2.47 times of that with a full-bridge rectifier, and which is in good agreement with the simulation result. The circuit efficiency and criteria for the inductor selection were clarified through circuit analysis based on spice simulation. It is found that the power dissipation of voltage-divider and rectification diodes becomes pronounced as the load voltage increases, constraining the efficiency. The inductor, which usually dominates the circuit volume, can be miniaturized for electret EHs, because the voltage inversion ratio, a benchmark of the SSHI performance, turns out to be insensitive to the series resistance of the inductor. The self-powering ability of the proposed circuit is also presented.

Dynamic Response and Stability Margin Improvement of Wireless Power Receiver Systems via Right-Half-Plane Zero Elimination

The series-series compensation topology is widely adopted in many wireless power transfer applications. For such systems, their wireless power receiver part typically involves a DC-DC converter with front-stage full-bridge diode rectifier, to process the high-frequency transmitted AC power into a DC output voltage for the load. It is recently reported that the current source nature of the series-series compensation will introduce right-half-plane (RHP) zeros into the small-signal transfer functions of the DC-DC converter of the wireless power receiver, which will severely affect the stability and dynamic response of the system. To resolve this issue, in this paper, it is proposed to adopt a different rectifier configuration for the system such that the input current to the DC-DC converter becomes controllable to eliminate the presence of RHP zeros of the small-signal transfer functions of the system. This rectifier can be applied to different wireless power receivers using the buck, buck-boost, or boost converters. As compared with the original wireless power receivers, the modified ones feature minimum-phase characteristics and hence ease the design of compensator. Theoretical and experimental results are provided. The comparative experimental results verify the elimination of the RHP zero, improved dynamic responses of reference tracking and against load disturbances, and a larger stability margin.

A novel control circuit for piezoelectric energy harvesting

A novel piezoelectric energy harvesting circuit is proposed. This circuit consists of a piezoelectric element, synchronized switch harvesting on capacitors (SSHC) circuit, two sampling resistors, control circuit, full-bridge rectifier, and load. The control circuit is composed of a zero-crossing detection circuit and a pulse generation circuit. The zero-crossing detection circuit adopts sampling resistance method, which is more accurate and easier to implement than the traditional voltage comparison method. The control signal for controlling switches in the SSHC circuit is generated by pulse generation circuit and its width is dynamically adjusted according to the state of the flipping process. Compared with circuit that uses capacitors to control the width of the control signal, this circuit is easier to implement and has a higher output efficiency. Experiment results show that the circuit proposed can accurately detect the zero-crossing time and automatically adjust the pulse width of the control signal according to the state of the circuit. The output power of the proposed circuit is 1.80 ​mW with 10 ​kΩ load resistance, which is four times that of the traditional SSHC circuit.

PWM-Controlled Series Resonant Converter for Universal Electric Vehicle Charger

This article presents a pulsewidth modulation (PWM) controlled series resonant converter (SRC) for a universal EV charger. This article focuses on the boost mode of a SRC. By adapting two PWM boost switches with a full bridge rectifier, it is possible for a SRC to cover a very wide range of gain with a high and flat efficiency curve. As the output voltage increases, the secondary side rectifier of the proposed converter gradually converts from a full bridge rectifier to a voltage doubler rectifier. Since the switching frequency is fixed to the resonant frequency in boost mode, the proposed converter naturally achieves “two peak efficiency points” with full bridge and voltage doubler rectifiers. Two peak efficiency points limit the efficiency drop over a wide range of gain, and that is the reason the proposed converter achieves a high and flat efficiency curve. The effectiveness of the proposed converter and control has been verified on an 800 V input and 200-950 V/3.3 kW output prototype.

An Improved Rectifier Circuit for Piezoelectric Energy Harvesting from Human Motion

Harvesting energy from human motion for powering small scale electronic devices is attracting research interest in recent years. A piezoelectric device (PD) is capable of harvesting energy from mechanical motions, in the form of alternating current (AC) voltage. The AC voltage generated is of low frequency and is often unstable due to the nature of human motion, which renders it unsuitable for charging storage device. Thus, an electronic circuit such as a full bridge rectifier (FBR) is required for direct current (DC) conversion. However, due to forward voltage loss across the diodes, the rectified voltage and output power are low and unstable. In addition, the suitability of existing rectifier circuits in converting AC voltage generated by PD as a result of low frequency human motion induced non-sinusoidal vibration is unknown. In this paper, an improved H-Bridge rectifier circuit is proposed to increase and to stabilise the output voltage. To study the effectiveness of the proposed circuit for human motion application, a series of experimental tests were conducted. Firstly, the performance of the H-Bridge rectifier circuit was studied using a PD attached to a cantilever beam subject to low frequency excitations using a mechanical shaker. Real-life testing was then conducted with the source of excitation changed to a human performing continuous cycling and walking motions at a different speed. Results show that the H-Bridge circuit prominently increases the rectified voltage and output power, while stabilises the voltage when compared to the conventional FBR circuit. This study shows that the proposed circuit is potentially suitable for PEH from human motion.

On the Sizing of the DC-Link Capacitor to Increase the Power Transfer in a Series-Series Inductive Resonant Wireless Charging Station

Wireless inductive-coupled power transfer is a very appealing technique for the battery recharge of autonomous devices like surveillance drones. The charger design mainly focuses on lightness and fast-charging to improve the drone mission times and reduce the no-flight gaps. The charger secondary circuit mounted on the drone generally consists of a full-bridge rectifier and a second-order filter. The filter cut-off frequency is usually chosen to make the rectifier output voltage constant and so that the battery is charged with continuous quantities. Previous works showed that an increase in power transfer is achieved, if compared to the traditional case, when the second-order filter resonant frequency is close to the double of the wireless charger excitation and the filter works in resonance. This work demonstrates that the condition of resonance is necessary but not sufficient to achieve the power increment. The bridge rectifier diodes must work in discontinuous-mode to improve the power transfer. The paper also investigates the dependence of the power transfer increase on the wireless excitation frequency. It is found the minimum frequency value below which the power transfer gain is not possible. This frequency transition point is calculated, and it is shown that the gain in power transfer is obtained for any battery when its equivalent circuit parameters are known. LTSpice simulations demonstrate that the transferred power can be incremented of around 30%, if compared to the case in which the rectifier works in continuous mode. This achievement is obtained by following the design recommendations proposed at the end of the paper, which trade off the gain in power transfer and the amplitude of the oscillating components of the wireless charger output.

Piezoelectric nanogenerators with high performance against harsh conditions based on tunable N doped 4H-SiC nanowire arrays

Piezoelectric nanogenerators (PENGs) have been attracting much attention for their high flexibility, low density and outstanding chemical stability in applications of environmental energy harvesting and self-powered sensors. Here, PENGs based on large scale free-standing N doped 4H-SiC nanowire arrays (NWAs) fabricated by anodic oxidation of single-crystalline N doped 4H-SiC wafer are proposed for the first time. Due to N-dopants bring the SiC semiconductors an enhanced piezoelectric performance, the as-prepared PENGs show excellent performance with the peak values of open circuit voltage and short circuit current density of 3.0 V and 200 nA cm −2 , respectively. Service stability of PENGs has been proven by 20,000 consecutive charge-discharge cycles as well. Moreover, the PENGs exhibit high thermal stability against 200 °C and excellent acid-base resistance. The energy generated by PENGs is enough to charge capacitors through a full bridge rectifier without any external power supply, certifying that they can work as standalone nanoscale energy sources. These results innovatively expand the feasibility of 4H-SiC for application in a wide variety of high-performance energy harvesting devices. Piezoelectric nanogenerators based on large-scale freestanding N doped 4H-SiC nanowire arrays with outputs of 3.0 V and 200 nA cm −2 are reported. The as-prepared nanogenerators have a long service life and show good anti-interference ability to frequency. They exhibit high thermal stability against 200 °C and excellent acid-base resistance, and can be widely used in various demanding workplaces. • Piezoelectric nanogenerators based on tunable N doped 4H-SiC nanowire arrays are first reported. • N doping enhances the piezoelectricity of 4H-SiC. • The as-prepared piezoelectric nanogenerators exhibit high thermal stability against 200 ℃ and excellent acid-base resistance.

Self-Powered SSDCI Array Interface for Multiple Piezoelectric Energy Harvesters

To merge the gap between the low-power output of piezoelectric energy harvesters (PEHs) and the high-power demand of sensors of Internet of Things, researchers recently start to explore PEHs arrays. However, few circuits have been developed to manage the multiple ac inputs from PEHs arrays. This article presents a self-powered PEH array interface circuit based on the synchronized switching and discharging to a storage capacitor through an inductor (SSDCI) technique. The array interface can output a maximum total power greater than the sum of each individual peak power, and achieve a high efficiency when multiple PEHs connect to the SSDCI array circuit. Simulation and experiment are performed to demonstrate the advantages of the SSDCI array interface. The tested results show that the designed SSDCI array circuit achieves an efficiency of 82.3% with three input sources, and allows a gain up to 300% in terms of maximal output power compared to the full-bridge rectifier. In addition, only the peak detection is utilized for the switching control; therefore, the SSDCI array circuit is realized more easily and with fewer components compared to the existing synchronous electric charge extraction array interfaces.

Analysis of Piezoelectric Energy Harvesting Interface Circuit Applied to Automobile Engine Vibration

In order to realize the continuous power supply for the vibration fault monitoring system of automobile engine, aiming at the low efficiency and instability of the existing piezoelectric full bridge rectifier energy collection circuit, this paper proposes a circuit scheme based on synchronous charge extraction. The scheme can provide circuit collection efficiency, and analyze the power of the circuit by impedance analysis. Finally, the experiment shows that the theoretical analysis is consistent with the experimental results. And the synchronous electrical charge extraction circuit can harvest power up to 1.3mW under low frequency conditions, which is higher than 0.5mW collected by the full-bridge rectifier circuit under the same conditions. The harvested energy meets the power requirements of automotive sensors and microcontrollers.

Research on Self-exciting Air-core Pulsed Alternator Considering Armature Reaction

Compared with the traditional synchronous generator with iron core structure, air-core pulse alternator usually adopts self-excitation to establish a higher field current to meet its demand for high flux density. In this paper, the topology of the self-exciting rectifier is determined to be the full bridge rectifier by discussing the respective application scope of the full bridge and the half wave rectifier. Considering the armature reaction, the self-excitation process and the coupling relationship between the field winding and the armature winding are analyzed. According to the commutation overlap angle, the equivalent circuits of different states are carried out, and the instantaneous expressions of field current and armature current are deduced, which lays a foundation for the following phase control research.

Simplified Brushless Wound Field Synchronous Machine Topology Based on a Three-Phase Rectifier

This paper proposes a novel simplified brushless wound field synchronous machine (BL-WFSM) topology based on an uncontrolled three-phase rectifier. The output of the rectifier is injected into the common point of the star-connected three-phase armature winding. This arrangement develops an armature MMF consisting of two components: the fundamental MMF, which is rotating in nature, and the harmonic pulsating magnetic field, which induces the harmonic current in the specially designed harmonic winding of the rotor. The induced harmonic current is rectified through the full-bridge rectifier, which excites the main rotor field to achieve brushless operation and produce torque while interacting with the main fundamental rotating field of the armature. The proposed brushless topology is simple as it involves a single three-phase rectifier which does not require any complicated control strategy. Furthermore, this topology is a cost-effective solution as compared to the conventional brushless WFSM topologies since it does not require any additional hardware component except for a typical rectifier. In addition, the performance of the proposed brushless topology is better than the existing three-phase rectifier-based brushless scheme in terms of efficiency, output torque, and torque ripple. The proposed simplified BL-WFSM topology is validated through 2-D finite element analysis (FEA) using JMAG-Designer 19.1 to obtain the output torque of the machine.

Research on Voltage and Current Acquisition from and Feedback Protection of Steam Recycling System of Power Plant Cooling Towers

The author introduces a technical method that combines dual-loop acquisition of voltage and current in the high voltage circuit and CPU automatic regulation of frequency duty ratio with high-precision voltage-to-frequency conversion chips. It is proposed to improve the accuracy of voltage and current acquisition from the steam recycling system of power plant cooling towers as well as the real-time performance, and to achieve long-term stable operation of the steam recycling system. Firstly, full wave bridge rectifiers and high voltage resistors are used to rectify high voltage into low voltage and current, which helps solve the problems involving insulation of high-voltage acquisition. Secondly, the overall circuit for voltage and current acquisition and feedback protection is designed according to the control system of the steam recycling system and the pulse frequency counting method. Finally, experimental data of output voltage, current and frequency are obtained through experiments and testing to analyze the accuracy and real-time performance of the overall circuit. The experimental results show that this method can effectively improve the accuracy of voltage and current acquisition and the real-time performance of overvoltage and overcurrent protection in the steam recycling system.

Mid-Range Wireless Power Transfer System for Various Types of Multiple Receivers Using Power Customized Resonator

This paper presents a high-efficiency wireless power transfer (WPT) system that can charge multiple receivers (Rx's) of various types. For system analysis, the transmitted power and received power levels are derived using the parameters of the resonators based on electro-magnetic (EM) resonance. Using the analysis results, the power customized resonator (PCR) not only for deriving sufficient output power from the transmitter (Tx) but also for appropriately distributing the received power to the various and multiple Rx's is proposed. In addition to the PCR, the Tx unit is designed to work as a load-dependent voltage source using a differential Class-E power amplifier (PA) through a wide range of load impedances. Therefore, the Tx can naturally adapt to the required Tx power levels with a high efficiency corresponding to various Rx configurations without additional tunable circuits or adaptive control schemes. The WPT system, including the load-dependent voltage source for the Tx, full-bridge rectifiers for the Rx's, and the proposed PCR, was designed for the 6.78 MHz frequency band. The proposed system is validated for use with multiple mobile devices by conducting experiments with nine charging cases using three types of Rx's. For all cases, high system efficiencies of 70.7-85.5% were maintained over received power levels of 8.6-45.7 W at a charging distance of 30 mm, and each of the three types of Rx's were experimentally verified to receive sufficient power.

A Self-Powered and Area Efficient SSHI Rectifier for Piezoelectric Harvesters

This article presents an area efficient fully autonomous piezoelectric energy harvesting system to scavenge energy from periodic vibrations. Extraction rectifier utilized in the system is based on synchronized switch harvesting on inductor (SSHI) technique which enables system to outperform standard passive rectifiers. Compared to conventional SSHI circuits, enhanced SSHI (E-SSHI) system proposed in this paper uses a single low-profile external inductor in the range of $\mu \text{H}$ ’s to reduce overall system cost and volume, hence broadening application areas of such harvesting systems. Furthermore, E-SSHI does not include any negative voltage converter circuit and therefore, it offers area efficient AC/DC rectification. Detection of optimal voltage flipping times in E-SSHI technique is conducted autonomously without any external calibration. Energy transfer circuit provides control over how much energy is delivered from E-SSHI output to electronic load. The proposed system is fabricated in 180 nm CMOS process with 0.28 mm2 active area. It is tested using a commercial piezoelectric transducer MIDE V22BL with periodic excitation. Measured results reveal that E-SSHI circuit is capable of extracting up to 5.23 and 4.02 times more power compared with an ideal full-bridge rectifier at 0.87 V and 2.6 V piezoelectric open circuit voltage amplitudes (VOC, P), respectively. A maximum voltage flipping efficiency of 93% is observed at VOC,P = 3.6 V, owing to minimized losses on charge flipping path. Measured results are compared with state-of-the-art interface circuits. Comparison shows that E-SSHI design offers a huge step towards miniaturized harvesting systems thanks to its low-profile and fully autonomous design.

A Harvesting Circuit for Flexible Thin-Film Piezoelectric Generator Achieving 562% Energy Extraction Improvement With Load Screening

In this article, a novel energy harvesting (EH) interface for a flexible thin-film piezoelectric generator (FPEG) is proposed for EH from irregular human motion. The traditional thick piezoelectric generator (PEG) based kinetic EH circuits are designed for continuous and sinusoidal inputs from the cantilever-based structures and are not suitable for EH from irregular human motion. The proposed EH interface circuit significantly enhances energy extraction with a load-screening scheme, which minimizes the load capacitance to maximize the PEG output voltage up to 102 V while using the standard voltage 0.18- <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> m process. An energy-aware wake-up controller is designed to (monitor and) detect the FPEG deformation to assure that the harvesting interface is only activated when enough energy is available for EH. When the FPEG voltage peaks, the energy is transferred to the battery through an inductor with a single-cycle buck-converter-like operation, allowing the input voltage and frequency-independent EH operation. The measurement results show that the proposed EH interface successfully harvests energy from irregular pulsed inputs with 562% improvement compared with a full-bridge rectifier.

Charging equaliser based on wireless power transfer for electric scooters

It is more convenient and safer to employ wireless power transfer (WPT) systems to charge the battery pack of electric scooters (ESs) than conventional plug-in systems. A charging equaliser suitable for ESs is proposed to achieve constant current (CC) output without communication link between the transmitter side and the receiver side. The full-bridge rectifier and select switches utilised at the receiver side are employed to be operated once to change from the balancing mode to charging modes. The characteristics of the load-independent current output in the CC mode are achieved by properly selecting the parameters of the circuit so that no sophisticated control strategies are required to regulate the output as per the charging profile. The experimental results show that when the voltage of battery pack is charged at 32 or 4.2 V, the current is 1.02 or 1.12 A, respectively. Therefore, the proposed system can be considered as a CC system.