Passive Diode Research Articles

Investigation of a power factor correction converter utilizing SEPIC topology with input current switching

The single-ended primary-inductor converter (SEPIC) is a popular converter topology that can be employed in diverse application fields where the needed output voltage is greater or lesser than the input voltage. The non-inverted output voltage of a SEPIC converter provides additional advantages when compared to a buck-boost or Ćuk converter. Furthermore, the position of the capacitor in the SEPIC converter provides inherent isolation and circuit safety. One drawback in the conventional bridge-diode SEPIC AC-DC converter is the lack of controllability which can be overcome by adding extra active switch(es) or by replacing the passive diode(s) with active switch(es). However, introducing more active switches increases the control complexity and may increase the requirement for additional driver circuits. To address this trade-off, this article proposes a single-phase AC to DC modified SEPIC converter with input current-switching capability without adding any extra active switch(es). The existing active switch of the DC-DC SEPIC converter was shifted towards the input side and thus no additional switch has been introduced. This allows the option of input-current switching without any additional complexity in the control or driver circuit. The circuit topology, principles of operation, and ideal voltage gain equations for the suggested circuit have been derived and included in this research work. The proposed circuit has been simulated in both open-loop conditions and closed-loop control with varying duty cycles and output load. Results from the simulation show that the proposed converter provides better efficiency (∼90 %) and lower total harmonic distortion (THD) (10 %) for varying duty cycles when compared to a conventional converter. The converter also shows good dynamic response. A low-power 15V hardware prototype has been built to experimentally validate the performance of the proposed converter. Experimental results illustrate that the suggested converter can improve the power factor by up to 0.968 while operating at an efficiency above 75 %. This converter topology can be suitable for applications where high output voltage gain, high power factor, and lower THD are needed without isolation requirements.

Visible nonreciprocal light propagation based on titanium nitride and gold in tandem

The disappearance of the permittivity of epsilon-near-zero (ENZ) materials can significantly enhance the optical nonlinear absorption, which provides a feasible way to realize broadband optoelectronic devices. Here, we used titanium nitride (TiN) film with ENZ wavelength at 540 nm as the saturable absorber (SA), and hexagonal gold nanolayer as the reverse saturable absorber (RSA), which are arranged in tandem to fabricate a broadband nonreciprocal passive photonic diode, and the maximum nonreciprocity factor of 4.8 dB was obtained experimentally in the ENZ region. Our results show the potential applications of TiN in nonlinear optical devices, and may make inroads towards the ENZ-based high-performance broadband optoelectronic devices.

A dual source switched-capacitors multilevel inverter topology with extended voltage levels and voltage gain

The switched-capacitors multi-level inverters (SCMLI) are widely used in renewable energy resources for enhancing the quality and reliability of generated power. This paper suggests a new topology of extendable voltage levels and voltage gain units using switched capacitors SC with a dual DC source. The proposed unit can be extended by a modular pattern to increase the output voltage levels and voltage-boosting gain of the inverter. The main feature of this work is presenting a unit topology that utilizes multiple and modular sub-cells to increase the voltage gain at the output by increasing the number of the sub-cell components. A ternary relationship of the voltage magnitudes between the two asymmetrical DC sources is mandatory. Furthermore, all the capacitors are self-balanced, so there is no need for any additional and complex control circuit. Moreover, to decrease the cost factor of the inverter, a low IGBT switch count is taken into consideration and no passive diodes are used in the proposed structure. The H-bridge is connected to the unit to achieve bipolar voltage at the output. The operational analysis of the inverter is delineated in detail. A comparative study with state-of-art MLIs in different terms such as the number of components, the total standing voltage, the cost factor, and the gain shows the particularity of the proposed topology. The simulation of the proposed MLI is performed using PSCAD-EMTDC software. An experimental prototype is built to validate the simulation results.

Analysis of the depth of penetration of an epoxy resin-based sealer following a final rinse of irrigants and use of activation systems: An in vitro study.

The objective of the study was to compare and evaluate the depth of penetration of an epoxy resin-based sealer following a final rinse of 17% ethylenediaminetetraacetic acid (EDTA) and 18% 1-hydroxyethylidene 1, 1-diphosphonate (HEDP), with diode laser and passive ultrasonic activation (PUI): an in vitro confocal laser scanning microscopy study. Fifty-two extracted human mandibular premolar teeth with single root and single canal were selected. They were disinfected in 0.1% thymol solution, cleaned of calculus and soft tissues, and stored in 0.1% thymol solution till use. All teeth were radiographed and selected as per the inclusion and exclusion criteria. The teeth were decoronated using a diamond disk under copious water spray to acquire a standardized root length of 14 mm. Working length was established by inserting a size 10-K file into each root canal until it is visible at the apical foramen and by subtracting 1 mm from the recorded length. Instrumentation of the root canal was done till master apical file size of F3 using ProTaper universal, rotary instruments. The canals were irrigated with 2 mL of 3% sodium hypochlorite between successive files. Teeth were randomly divided into four subgroups n = 12 according to the intervention. Passive ultrasonic irrigation and diode laser were used to activate the irrigants. Final irrigation was performed with distilled water. These specimens were examined using confocal laser scanning microscope (OLYMPUS FLUOVIEW FV 3000) for dentinal tubule penetration of the sealer. Two-way ANOVA test and Tukey's multiple post hoc test were used for statistical analysis. Highly significant difference was seen between the groups with EDTA and HEDP, with HEDP demonstrating the highest penetration. Among the activation techniques used in this study, PUI showed the highest penetration of the sealer. The least penetration was seen with diode laser activation and EDTA. The irrigation activation techniques significantly influence the penetration of sealer into root dentinal tubules. When penetration of sealer with different irrigation techniques and irrigants was evaluated, significant greater level of sealer penetration was attained with PUI activation of HEDP.

All-optical passive photonic diodes based on perovskite and transparent conducting oxide material

Low dimensional perovskite emerging as a highly promising class of functional materials for semiconductor optoelectronic applications have drawn great attention. Here, we report the nonlinear absorption of low-dimensional perovskite PEA2PbI4 and transparent conducting oxide material Aluminum-doped zinc oxide (AZO) with operating spectral window in telecommunications. Then we fabricate all-optical diodes with nonreciprocity factor of 10.1 dB based on the reverse saturable absorber (PEA2PbI4) and the saturable absorber (AZO). The results show the potential applications of perovskite-based materials in all-optical diode, and may pave way for the development of high-performance photonic devices.

Ultra-sensitive voltage-controlled skyrmion-based spintronic diode

We have designed a passive spintronic diode based on a single skyrmion stabilized in a magnetic tunnel junction and studied its dynamics induced by voltage-controlled magnetic anisotropy (VCMA) and Dzyaloshinskii–Moriya interaction (VDMI). We have demonstrated that the sensitivity (rectified output voltage over input microwave power) with realistic physical parameters and geometry can be larger than 10 kV W−1 which is one order of magnitude larger than diodes employing a uniform ferromagnetic state. Our numerical and analytical results on the VCMA and VDMI-driven resonant excitation of skyrmions beyond the linear regime reveal a frequency dependence on the amplitude and no efficient parametric resonance. Skyrmions with a smaller radius produced higher sensitivities, demonstrating the efficient scalability of skyrmion-based spintronic diodes. These results pave the way for designing passive ultra-sensitive and energy efficient skyrmion-based microwave detectors.

A comparative evaluation and real-time measurement of failures in solar power plants by thermal imaging in Turkey

The demand for electricity generated from solar energy in Turkey is increasing daily. For sustainability in energy, a good design, periodic operational maintenance and instant monitoring of the field all play important roles when generating photovoltaic power. Fast and on-site detection of failures in photovoltaic fields is required to ensure long-term, high-efficiency photovoltaic power generation. On-site testing of solar power systems is useful for evaluating the performance of facilities and identifying potential problems. Thermal imaging of photovoltaic modules and electrical components is the most reliable inspection method compared with other methods. In this article, thermal imaging results from eight different Turkish solar power plants (23.5 MWp in total) are reported. We found that the most common difficulties identified during field tests could be classified according to the type of failure. This experiment demonstrates the efficiency and effectiveness of the thermal imaging approach, both in terms of accuracy and processing time. Passive bypass diodes, connection failures and hot spots in photovoltaic modules and strings, abnormally exploded fuses, and panel cracking and breakage were the main causes of these failures.

Three Cascaded Nano-Mechanical Microring Resonators Enable High-Efficient Optical Diodes

We propose and experimentally demonstrate a passive nano-mechanical optical diode with ultra-high nonreciprocal transmission ratios (NTRs) and low-power consumption based on the significantly enhanced light-matter interaction in three cascaded opto-mechanical microring resonators (MRRs). In the experiment, an ultra-high NTR beyond 50 dB could be achieved with requiring an optical power as low as -3.8 dBm based on the silicon devices for the first time. To the best of our knowledge, it is a record for on-chip passive optical diode by simultaneously considering the NTRs and the power consumption. With dominant advantages of ultra-high NTRs, low-power consumption, compact size and complementary metal-oxide semiconductor (CMOS) compatibility, the energy-efficient nano-mechanical optical diode has extensive applications in on-chip high-efficient optical signal processing.

Compact and Low Power-Consumption Solid-State Two-Dimensional Beam Scanner Integrating a Passive Optical Phased Array and Hybrid Wavelength-Tunable Laser Diode

Large-scale optical phased arrays have attracted attention as devices for solid-state beam scanning employing light detection and ranging. However, conventional optical phased arrays using electro-optic phase shifters require active phase control for each antenna. Because the power consumption of the active phase shifters is proportional to the number of antennas, the total power consumption increases in a large-scale optical phased array with a narrow beam divergence. In this study, we propose a passive beam scanner that realizes two-dimensional beam scanning through the wavelength sweep of a laser light. Additionally, most studies on optical phased arrays use external laser diodes as light sources. This increases the size of the beam-scanning system. Therefore, there is a demand for integrating an optical phased array and a laser light source in a combined chip. In this study, we integrated a 64-channel passive optical phased array and a hybrid wavelength-tunable laser diode into a combined chip. The size of the device was 5 mm × 1.5 mm, and the power consumption for beam scanning was 49.3 mW. The field of view was 44.2° × 13.7°, and the full width at half maximum of the beam divergence was 0.517° × 3.67°. Compared with the device used in a previous study, our device was nine times smaller, and the total power consumption was only tens of milliwatts. This device consumes less power and achieves a fully integrated light detection and ranging.

A Novel Passive Resonant Pole Inverter With High Efficiency and High Reliability

For the efficiency improvement of the inverters, a novel passive resonant pole inverter with high reliability is proposed in this brief. Passive devices, including inductors, capacitors and diodes, constitute the auxiliary circuits of each phase. When the passive auxiliary circuits work in commutation process of the inverter, main switching devices will attain soft-switching, thus reducing the switching loss and achieving the purpose of optimizing the efficiency. In addition, the switching devices are not subjected to the voltage which is more than the DC supply voltage, avoiding the damage of switching devices caused by over-voltage and achieving the high reliability of the novel inverter. This brief illustrates each working state in a switching period. The relative experimental waveform indicates that switching devices attain soft-switching. Furthermore, the efficiency of the novel inverter achieves 98% at rated output power. Thus, the novel inverter is more advantageous in efficiency than other similar soft-switching inverters.

Trace photoacoustic SO2 gas sensor in SF6 utilizing a 266 nm UV laser and an acousto-optic power stabilizer.

A sulfur dioxide (SO2) gas sensor based on the photoacoustic spectroscopy technology in a sulfur hexafluoride (SF6) gas matrix was demonstrated for SF6 decomposition components monitoring in the power system. A passive Q-switching laser diode (LD) pumped all-solid-state 266 nm deep-ultraviolet laser was exploited as the laser excitation source. The photoacoustic signal amplitude is linear related to the incident optical power, whereas, a random laser power jitter is inevitable since the immature laser manufacturing technology in UV spectral region. A compact laser power stabilization system was developed for better sensor performance by adopting a photodetector, a custom-made internal closed-loop feedback controller and a Bragg acousto-optic modulator (AOM). The out-power stability of 0.04% was achieved even though the original power stability was 0.41% for ∼ 2 hours. A differential two-resonator photoacoustic cell (PAC) was designed for weak photoacoustic signal detection. The special physical constants of SF6 buffer gas induced a high-Q factor of 85. A detection limit of 140 ppbv was obtained after the optimization, which corresponds to a normalized noise equivalent absorption coefficient of 3.2 × 10-9 cm-1WHz-1/2.

2D Transition Metal Carbides (MXenes) for Third Order Nonlinear Optics: Status and Prospects

AbstractThe family of 2D transition metal carbides, nitrides, and carbonitrides (MXenes) has attracted an enormous amount of attention due to their tunable optical, electronic, electrochemical, and mechanical properties. Recently, a new branch of MXenes materials research has emerged that is exploring and engineering the intrinsic optical response of MXenes, resulting in compact nonlinear optical (NLO) devices. As a novel 2D materials system, MXenes not only exhibit common advantages of classical 2D materials for NLO applications but also demonstrate their unique superiority, such as high yield and scalable synthesis, good stability, switchable NLO response, etc. Here, a fundamental overview of MXenes nonlinear optics is provided, covering everything from MXenes synthesis to linear and NLO properties and NLO applications. The synthesis method and its influence on the MXenes structures and morphology are discussed, which dominated the linear optics of MXenes. Then, the third‐order NLO properties and carrier dynamics of MXenes, from basic theory to experimental results, are elaborated. Their NLO applications, including ultrashort laser pulse, single‐frequency laser generation, all‐optical phase modulation, wavelength modulation, and passive photonic diodes, are also highlighted. Finally, the current challenges and an outlook for future MXenes NLO research are proposed.

Analysis, Design, and Optimization of the IPT System With LC Filter Rectifier Featuring High Efficiency

Passive diode bridge rectifier with LC filter is widely used in wireless power transfer (WPT) system due to its simple structure and uncontrolled characteristics. However, as the load resistance decreases, its input phase angle will also decrease rapidly until it shows obvious capacitive. Therefore, a novel rectifier topology with an input-series inductor (hereafter called ISIR) is proposed in this article to solve this problem. What is more, the ISIR can avoid the duty cycle loss and improve the dc–dc efficiency. First, the mechanism of ISIR is analyzed in detail combined with the operating status of topology. Then, the inductance and compensation parameters are determined based on theoretical calculation and simulation results. Finally, a prototype with a maximum load of 7 Ω is built to validate the feasibility and effectiveness of ISIR, and 88% efficiency is achieved under this condition. Compared with the traditional method, it has increased by 1.05%. The maximum efficiency of WPT system is as high as 91.14% with the proposed ISIR.

Fault diagnosis algorithm for 3-phase passive rectifiers based on frequency-domain analysis for acceleration grid power supply in CFETR NBI system

The acceleration grid power supply (AGPS) is a crucial part of the Negative-ion Neutral Beam Injection system in the China Fusion Engineering Test Reactor, which includes a 3-phase passive (diode) rectifier. To diagnose and localize faults in the rectifier, this paper proposes a frequency-domain analysis-based fault diagnosis algorithm for the rectifier in AGPS. First, time-domain expressions and spectral characteristics of the output voltage of the TPTL-NPC inverter-based power supply are analyzed. Then, frequency-domain analysis-based fault diagnosis and frequency-domain analysis-based sub-fault diagnosis algorithms are proposed to diagnose open circuit (OC) faults of diode(s), which benefit from the analysis of harmonics magnitude and phase-angle of the output voltage. Only a fundamental period is needed to diagnose and localize exact faults, and a strong Variable-duration Fault Detection Method is proposed to identify acceptable ripple from OC faults. Detailed simulations and experimental results demonstrate the effectiveness, quickness, and robustness of the proposed algorithms, and the diagnosis algorithms proposed in this article provide a significant method for the fault diagnosis of other rectifiers and converters.

Enhanced nonreciprocal light propagation based on epsilon-near-zero medium in the visible regime

We have experimentally demonstrated the nonreciprocal light propagation based on the axially asymmetric nonlinear absorption in the epsilon-near-zero (ENZ) media titanium nitride (TiN) nanosheets and C60 arranged in tandem in the visible regime. TiN nanosheets have been prepared and characterized to show broadband and ultrafast nonlinear optical response with the maximum nonlinear absorption coefficient about −5.05×10−8 m/W at its ENZ wavelength, which is about ten times larger than that at 400 nm. With the enhanced nonlinear absorption of TiN nanosheets, a passive photonic diode fabricated with TiN-C60 in a tandem structure shows enhanced nonreciprocal transmission of femtosecond laser pulses with a nonreciprocity factor of 9.5 dB at the ENZ wavelength. The results show the potential applications of TiN nanosheets in ultracompact, polarization-independent, and physiochemically stable nonreciprocal light propagation and may pave way for the application of broadband ENZ-based all-optical devices.

Frequency Stability Transfer in Passive Mode-Locked Quantum-Dash Laser Diode Using Optical Injection Locking

In this paper, we present an experimental study of the metrological stabilization of a solid-state frequency comb for embedded metrology applications. The comb is a passively mode-locked laser diode based on InGaAs/InP Quantum-dash structure emitting optical lines into a 9 nm bandwidth centered at 1.55 $\mu$m with a repetition rate of 10.09 GHz. The frequency stabilization is achieved by optical injection locking of the comb with an external cavity laser diode referenced onto a metrological frequency standard. One observes the transfer of the spectral purity from the injection laser to the neighbouring modes of the injected one as well as the transfer of stability to the adjacent modes. The measurement of the long term stability highlights a frequency noise with random walk behavior specific of the passive mode locking process. Demonstration of sidebands of the injection laser at the repetition frequency of the comb also makes it possible to propose a transfer mechanism and to consider a complete stabilization of the frequency comb at a metrological stability level.

A Bidirectional Soft Diode for Artificial Systems

AbstractArtificial material systems that seek to mimic the basic processes of life must perform multiple complex functions, including responsiveness, motion, and metabolism. Networks of programmable materials offer a pathway toward achieving these functions by altering local chemical, physical, and structural properties to enable control. The ability to perform multiple complex functions in a single soft elastomeric material system is demonstrated by reconfiguring, in situ, passive bistable fluidic diodes that are inspired by mammalian venous valves. It is shown how pneumo‐mechanical programmability allows these silicone elastomer diode assemblies to accomplish, without rearranging the fluidic circuit, multiple functions, including pumping (motion), energy storage/discharge (metabolism), logic operations (response), and signal filtering/rectification. The ability to achieve multiple functions through in situ programming may lead to the development of efficient artificial systems capable of complex functions in compact, remote applications.

Dual Voltage Forward Topology for High Efficiency at Universal Mains

This paper introduces a forward converter aimed at the universal mains voltages, i.e., 220–230 Vac and 115 Vac, named the ‘dual voltage forward converter’. The suggested converter has a narrow dynamic range at the universal mains voltages, which results in lower stress on devices, optimal duty cycles, and better overall efficiency. The topology comprises two primary power loops reconfigurable by additional two-state switches and a passive diode, which allows the converter to run in parallel or in series modes and increase the performance over the full universal mains range of 90–265 Vac. The utilization of the devices is better, as they experience lower voltage and current stress by supporting two optimized working points. A converter operating at 100 kHz with an output power of 75 W and output voltage of 12 Vdc was designed and tested. The results were compared with a conventional forward converter with the identical specification. The results at the low mains were similar between the converters; however, at the high mains, the efficiency improvement was between 5% and 23%.

Asymmetric Generation of Acoustic Vortex Using Dual-Layer Metasurfaces.

In this Letter, we introduce a new paradigm for achieving robust asymmetric generation of acoustic vortex field through dual-layer metasurfaces by controlling their intrinsic topologic charges and the parity of geometry design. The underlying physics is contributed to the one-way process of orbital angular momentum (OAM) transition ensured by the broken spatial symmetry and the external topologic charge from the vortex diffraction. We further experimentally demonstrate this novel phenomenon. Our findings could provide new routes to manipulate the asymmetric response of vortex fields, including one-way excitation and propagation, and promise potential applications in passive OAM-based diodes.

Winding Layout Considerations for an Integrated Generator–Rectifier System

An integrated generator–rectifier system is a promising architecture to harvest energy in offshore wind turbines. The system processes the majority of the incoming power using reliable, efficient, and inexpensive passive diodes operating at the generator line frequency. Elimination of capacitors at the diode rectifiers’ output by appropriately phase shifting the voltages of a multiport generator further improves the reliability of the overall architecture. This article creates a generalized framework to evaluate the interactions among different generator ports, diode-bridge rectifiers, and the active rectifier that is used to control the power flow. The framework enables quantifying the effect of integration on the dc bus power ripple and power imbalance among different generator ports. An exemplary winding layout is proposed that ensures theoretically zero interaction between the passive ports, although all the ports are mounted on a magnetic structure. A 10-MW integrated generator–rectifier design and simulation proves the accuracy of the framework using coupled circuit and finite-element simulation. Finally, a laboratory prototype shows the realization of the winding layout. The proposed inductance-matrix-based framework can be used to evaluate other winding layouts to estimate the effect of magnetic coupling on the performance of the system.