Conventional Full-bridge Rectifier Research Articles

A self-powered extensible P–SSHI array interface circuit with thermoelectric energy assistance for piezoelectric energy harvesting

In this paper, a self-powered extensible parallel synchronized switch harvesting on inductor (EP-SSHI) interface is presented. The proposed interface addresses multiple piezoelectric transducers (PZTs) with arbitrary phase differences, while avoiding the conflict of accessing the single inductor simultaneously. In addition, the proposed interface enhances the voltage flipping performance of the PZT by incorporating thermoelectric energy assistance to increase its output power. Measurements demonstrate that the voltage flipping efficiency of the EP-SSHI with thermoelectric energy assistance (EP–SSHI–TEA) was increased to 53.33% with the assistance of 75 mV thermoelectric energy. Experimental results reveal that the proposed interface can effectively harvest energy from multiple PZTs with any phase difference. Compared with the conventional full bridge rectifier, the EP-SSHI achieves 3.63x power improvement and 6.42x load voltage range. Relative to other advanced circuits, the proposed interface strikes a superior balance between high output power and wide output voltage range while maintaining circuit simplicity and extensibility.

A Self-Powered FBRJT AC-DC Conversion Circuit for Piezoelectric Energy Harvesting Systems

In this study, a complete model for a miniature excitation-powered piezoelectric generator (PG), analysis modes of operation and control of a full-bridge joule thief (FBRJT) circuit to identify the optimal points were investigated. The proposed model revealed the PG’s power dependency on mechanical excitation, acceleration, and frequency and defined the load behaviour for power optimisation. The proposed circuit, namely FBRJT, was integrated with the conventional full-bridge rectifier (FBR) in Stage 1 for AC-DC conversion and with the joule thief circuit in Stage 2 for DC-DC conversion. This integration acted as a boost converter without utilising the duty cycles and additional switching components. The electrical nature of the input of FBRJT with a simple structure, sensor-less control and auxiliary circuits showed a consistent agreement with the investigated testing scenarios using both ideal and impedance power sources. Additionally, the performance of the proposed circuit was also verified against the published results of power electronics circuits. The developed versatile circuit and control system can be utilised for many applications, such as mobile battery charging and energy harvesting.

Low-voltage broadband piezoelectric vibration energy harvesting enabled by a highly-coupled harvester and tunable PSSHI circuit

This paper presents a system-level design approach for widening the bandwidth and lowering the operating voltage of a piezoelectric vibration energy harvesting system (PVEHS). The proposed strategy involves co-optimization of the two constituent parts: (1) a highly-coupled piezoelectric vibration energy harvesting device (PVEHD) and (2) a phase-shift tunable parallel-SSHI (PS-PSSHI) interface power-electronic circuit. First, we analyze the interaction between them to achieve an overall reduction of system voltage and to widen bandwidth. Next, a co-designed system is experimentally demonstrated to validate the analysis. The implemented PVEHS consists of (i) a customized PVEHD designed for high electromechanical coupling and well-separated short-circuit (f SC) and open-circuit (f OC) resonances, and (ii) a tunable PS-PSSHI circuit which has an active rectification with low voltage drop to increase system efficiency. The system achieves an output power of 148 µW with a bandwidth of 81 Hz, an increase of 337% compared to conventional full-bridge rectifier. In addition, the system rectification voltage is lowered by 30% which makes it viable to power low-voltage Internet-of-Things sensor nodes.

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.

Piezoelectric Energy-Harvesting Interface Using Split-Phase Flipping-Capacitor Rectifier With Capacitor Reuse for Input Power Adaptation

This article proposes a split-phase flipping-capacitor rectifier (SPFCR) to resolve the hard tradeoff between the number of capacitors and the energy-extraction efficiency for capacitive piezoelectric energy-harvesting (PEH) interfaces. By splitting the capacitor usage into multiple phases, this article can achieve the most number of flipping phases using the same number of capacitors when compared with the state of the art. We also relaxed the implementation complexity by removing insignificant SFPCR flipping phases without sacrificing the energy-harvesting efficiency. To improve further the input power adaptation, the flipping capacitors are reconfigured as a multiple-voltage-conversion-ratio (MVCR) switched-capacitor dc–dc converter during the non-flipping period without using extra passives. Maximum-power-point tracking (MPPT) is also accomplished using the full-bridge rectifier (FBR) fractional open-circuit voltage ( $V_{{\text {OC}, \text {FBR}}}$ ) to relax the voltage-tolerance requirements. Fabricated in 0.18- $\mu \text{m}$ CMOS, the proposed 21-phase SPFCR PEH interface demonstrates a measured maximum output power improving rate (MOPIR) of up to 9.3 $\times $ with $V_{D}= 0.12$ V (6.5 $\times $ with $V_{D}= 0$ V) when compared with the conventional FBR interface over an equivalent FBR input power range ( $P_{{\text {in, FBR}}}$ ) from 0.15 to 5.57 $\mu \text{W}$ .

MINIMIZED VOLTAGE DROP RECTIFIER CIRCUIT USING PIEZOELECTRIC TRANSDUCER FOR ENERGY HARVESTING

Piezoelectric systems produce an AC voltage signal at the output and to utilize this voltage, It is required to convert this AC signal into DC with the assistance of the rectifying circuit. The aim of this research is to minimize the voltage drop VD of the conventional diode by designing a diode circuit with the help of MOSFETs to be used in the rectifier. In conventional full bridge rectifier (Con-FBR) the power losses are very high because of diodes drop VD. To minimize these losses the Con-FBR circuit is altered with the employment of both n-type and p-type MOSFETs to be operated in the deep triode (ohmic) region while blocking the reverse leakage which results in reducing the threshold voltage VTH to few mV. Both positive and negative cycles are availed and investigated to extract the maximum output voltage. It is simulated in NI-Multisim (version 14.0) and is implemented using discrete components. The results show that the bridge rectifier using proposed low diode drop configuration has a better power conversion efficiency and can extract power ‘4’ four times more than the Con-FBR.

Dual-stage Electrode Design of Rotational Electret Energy Harvester for Efficient Self-powered SSHI

This paper presents a dual-stage electrode design for electret-based rotational energy harvester (EH) to improve efficiency of synchronized switch harvesting on inductor (SSHI) technique. With the aid of the present parallel SSHI circuit, output power of the rotational electret EH developed in our group becomes 4.2 times higher if compared with the conventional full-bridge rectifier.

Performance improvement of flexible piezoelectric energy harvester for irregular human motion with energy extraction enhancement circuit

Flexible piezoelectric energy harvesters (f-PEHs) have drawn attention for their potential use as power sources for wearable electronics. However, the amount of power harvested from conventional f-PEHs is still insufficient for achieving energy autonomy; hence, they are only used for limited applications. One of the effective approaches to enhancing the energy extraction from an f-PEH is to optimize the harvesting circuits. In this article, an energy extraction enhancement circuit (EEEC) using an f-PEH based on piezoelectric (PZT) material is reported to improve energy harvesting from irregular human movement of a joint or limb. The proposed EEEC is optimized for harvesting energy from random energy inputs with varying magnitudes and intervals, just like sporadic and irregular human movement. An f-PEH with a total thickness of 170 µm is utilized, which provides sufficient flexibility for attachment on clothes or human skin. By minimizing the capacitive load experienced by the PZT material during deformation, the EEEC maximizes the output voltage and increases the amount of extracted energy with low static power consumption (1.15 nW). Compared with a conventional full bridge rectifier (FBR)-based harvesting circuit, energy extraction is enhanced up to 495%.

An Efficient CMOS Dual Switch Rectifier for Piezoelectric Energy-Harvesting Circuits

In this research work, we investigated a dual switch (DS) active rectifier for the piezoelectric (PE) energy scavenging system. In the proposed DS active rectifier configuration, two extra switches are shunted across the PE transducer which helps the PE transducer’s capacitor in charging and discharging which results in maximum power extraction from the PE transducer. Moreover, in the proposed rectifier configuration comparator controlled active diodes are used instead of conventional/passive diodes to minimize the threshold voltage V T H drop. The proposed DS active rectifier design is fabricated in a 1-poly 6-metal 180-nm standard CMOS process. The simulation and measured results of the proposed DS active rectifier design have the better power conversion efficiency (PCE) of 91.5 %, which definitely helps in extracting more power than the conventional full bridge rectifier (FBR).

Self-powered SSHI for Electret Energy Harvester

A nonlinear power management circuit for electret-based energy harvesting is designed based on the synchronized switch harvesting on inductor (SSHI) technique. With the present circuit, the output power of rotational electret energy harvester is increased by 75% if compared with the conventional full-bridge rectifier.

An Efficient Inductorless Dynamically Configured Interface Circuit for Piezoelectric Vibration Energy Harvesting

Vibration energy harvesting based on piezoelectric materials is of interest in several applications such as in powering remote distributed wireless sensor nodes for structural health monitoring. Synchronized switch harvesting on inductor and synchronous electric charge extraction circuits show good power efficiency among reported power management circuits; however, limitations exist due to inductors employed, adaption of response to varying excitation levels, and the synchronized switch damping (SSD) effect. In this paper, an inductorless dynamically configured interface circuit is proposed, which is able to configure the connection of two piezoelectric materials in parallel or in series by periodically evaluating the ambient excitation level. The proposed circuit is designed and fabricated in a 0.35 μHV CMOS process.The fabricated circuit is cointegrated with a piezoelectric bimorph energy harvester and the performance is experimentally validated. With a low power consumption (0.5 μW), the measured results show that the proposed rectifier can provide a 4.5 × boost in harvested energy compared to the conventional full-bridge rectifier without employing an inductor. It also shows a high power efficiency over a wide range of excitation levels and is less susceptible to SSD.

Resonant Rectifier ICs for Piezoelectric Energy Harvesting Using Low-Voltage Drop Diode Equivalents.

Herein, we present the design technique of a resonant rectifier for piezoelectric (PE) energy harvesting. We propose two diode equivalents to reduce the voltage drop in the rectifier operation, a minuscule-drop-diode equivalent (MDDE) and a low-drop-diode equivalent (LDDE). The diode equivalents are embedded in resonant rectifier integrated circuits (ICs), which use symmetric bias-flip to reduce the power used for charging and discharging the internal capacitance of a PE transducer. The self-startup function is supported by synchronously generating control pulses for the bias-flip from the PE transducer. Two resonant rectifier ICs, using both MDDE and LDDE, are fabricated in a 0.18 μm CMOS process and their performances are characterized under external and self-power conditions. Under the external-power condition, the rectifier using LDDE delivers an output power POUT of 564 μW and a rectifier output voltage VRECT of 3.36 V with a power transfer efficiency of 68.1%. Under self-power conditions, the rectifier using MDDE delivers a POUT of 288 μW and a VRECT of 2.4 V with a corresponding efficiency of 78.4%. Using the proposed bias-flip technique, the power extraction capability of the proposed rectifier is 5.9 and 3.0 times higher than that of a conventional full-bridge rectifier.

Low-Harmonic-Contents and High-Efficiency Class E Full-Wave Current-Driven Rectifier for Megahertz Wireless Power Transfer Systems

Wireless power transfer (WPT) working at megahertz (MHz) is now being widely considered a promising candidate for the midrange transfer of a medium amount of power. Efforts have been made to build high-efficiency MHz WPT systems via both component- and system-level approaches. However, so far there have been few discussions on high-frequency rectifier for MHz WPT applications. The soft-switching-based rectifiers, such as the Class E rectifiers, are one of the promising candidates for MHz rectification. This paper investigates the application of a Class E full-wave current-driven rectifier, for the first time, in WPT systems. A procedure is also developed to optimize the design of the rectifier and the MHz WPT system. For comparison purposes, the performances of both the Class E rectifier and the conventional full-bridge rectifier are investigated in terms of total harmonic distortion (THD), efficiency, power factor, voltage/current stresses, and voltage/current transfer functions, when being applied in an example 6.78-MHz WPT system. The simulation and experimental results show that the input voltage THD of the Class E full-wave rectifier is reduced to one-fourth of the THD of the full-bridge rectifier. In the optimally designed MHz WPT system, efficiencies of both the rectification (over 91%) and the overall system (around 80%) are obviously improved compared to the system using the conventional full-bridge rectifier.

An Integrated High-Performance Active Rectifier for Piezoelectric Vibration Energy Harvesting Systems

In this letter, a highly efficient active full-bridge rectifier is proposed for piezoelectric (PE) vibration energy harvesting systems. By replacing the passive diodes with an operational amplifier-controlled active counterpart and adding a switch in parallel with the transducer, the proposed rectifier solves the dc-offset problem of the comparator-based active diode, minimizes the voltage drop along the conduction path, and extracts more power from the transducer, all of which lead to better power extraction and conversion capability. The proposed rectifier, implemented in 0.18-μm CMOS technology, shows 90% power conversion efficiency and 81 μW output power, with values corresponding to 1.5 times and 3.4 times the values for a conventional full-bridge rectifier.