- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Wide-Spectrum Pulsed Fiber Laser based on Picosecond Pulse Generation Supercontinuum
摘要： We demonstrated a wide-spectrum pulsed fiber laser by using supercontinuum (SC) generate from a narrow pulse width fiber laser pump into high nonlinear fiber (HNLF). The pulse width of wide-spectrum pulsed fiber laser is 7.95ps and the repetition frequency is 4GHz with a 20nm bandwidth. It is found that the anomalous dispersion region near the zero dispersion wavelength has a better stability by observing the wide spectrum pulses in different bands.
关键词： different dispersion region,super-continuum,wide-spectrum pulsed fiber laser,narrow pulse width
更新于2025-11-28 14:24:03
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Widely Wavelength-tunable Mode-locked Fiber Laser Based on a 45° Tilted Fiber Grating and Polarization Maintaining Fiber
摘要： We present a passively mode-locked Erbium-doped fiber laser with tunable parameters including central wavelength, 3dB bandwidth and pulse duration. The mode-locking mechanism of the laser is realized by using single-walled carbon nanotubes polyvinyl alcohol (SWCNTs-PVA) composite film as saturable absorber. The tunable operation is implemented via a fiber birefringence filter consisting of a polarization maintaining (PM) fiber and a Brewster fiber grating. The laser achieves a maximum spectral tuning range of 36 nm with 8 cm PM fiber. The maximum spectral width variation of 5.19 nm is acquired when the PM fiber is 12 cm. Simultaneously, the spectral widths of pulses at different central wavelengths are also adjustable. Furthermore, the total cavity length is 8.28 m, which is the shortest cavity length to obtain such wide tuning range in an Erbium-doped fiber laser based on SWCNTs.
关键词： Passively mode-locked fiber laser,spectral width,wavelength-tunable,pulse width,tilted fiber grating
更新于2025-11-28 14:23:57
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PWM as a Low Cost Method for the Analog Control of MEMS Devices
摘要： In this paper, we discuss the use of pulse width modulation (PWM) to control analog MEMS devices. We achieve a precise linear analog control of MEMS by applying PWM signal with a frequency well above the system’s mechanical natural frequency. We first demonstrate this using a parallel plate actuator and comb-drive, and then extend the technique to control a commercial deformable mirror. Such an approach allows the system designer to replace expensive drive electronics such as the high precision DACs and high voltage, linear amplifiers with a simple on-off switch. The advancements in the electronics industry tend to make precise timing cheaper and faster; our approach exploits these long-term trends to create low-cost control circuits. We also show how PWM control can linearize the positional response of the devices, where typically the position would depend quadratically on the applied analog voltage.
关键词： linearize,pulse width modulation,Microelectromechanical systems,electrostatic actuator
更新于2025-09-23 15:22:29
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All-optical regenerative technique for width-tunable ultra-wideband signal generation
摘要： We demonstrate all-optical generation of width-tunable mono-cycle pulses for ultra-wideband communication. It has been shown that the width of the mono-cycle pulses can be tuned dynamically by simply varying the power of the optical signal. We also investigate the regenerative property of the nonlinear medium-based technique for the generation of mono-cycle pulses. For the purpose of comparison, ultra-wideband mono-cycle pulses are also generated through the optical delay line-based technique. It has been demonstrated through numerical simulations that the nonlinear medium-based technique is highly resilient to amplified spontaneous emission noise that is induced over the optical signal. Furthermore, we have shown that the highly nonlinear fiber-based nonlinear medium performs better than the semiconductor optical amplifier-based medium. Bit error rate measurements are taken for different values of optical signal-to-noise ratios in order to elaborate our work.
关键词： Gaussian mono-cycle pulses,Ultra-wideband over fiber,Semiconductor optical amplifier,Pulse width tuning,Highly nonlinear fiber
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 6th Workshop on Advances in Information, Electronic and Electrical Engineering (AIEEE) - Vilnius, Lithuania (2018.11.8-2018.11.10)] 2018 IEEE 6th Workshop on Advances in Information, Electronic and Electrical Engineering (AIEEE) - 18-pulse Rectifier with Electronic Phase Shifting with Autotransformer in Inverter and Rectifier Mode
摘要： To reduce harmonic distortion of the input current, multipulse rectifiers are used. They require the presence of phase-shifting transformers or autotransformers. Elimination of electromagnetic phase-shifting devices while maintaining small harmonic distortion of the input current and obtaining a power factor close to unity is possible with the use of electronic phase shift. The electronic phase shift is realized by means of the rectifier itself: the introduction of positive and negative control angles in the pairs of rectifiers’ modules. At present, 12-pulse rectifiers with electronic phase shift are known. Unlike classic rectifiers, they do not use phase-shifting transformers and have a unit power factor. Increasing of the rectifier’s pulse makes it possible to improve the harmonic composition of the input current. The use of the principle of electronic phase shift in 18-pulse rectifier leads to different levels of constant voltage at the output of the rectifiers. In this case, to equalize the currents of rectifiers’ modules, one can use both an increase the voltage at the input of rectifiers operating with large control angles and a decrease the input voltage of the rectifiers operating with smaller control angles. The principles of constructing of matching autotransformers for the 18-pulse rectifier with an electronic phase shift are considered in the article. Comparison of 18-pulse rectifiers with use of step-up and step-down autotransformers is made. Data on the installed capacity of autotransformers, power losses are obtained. The results of thermophysical modeling are presented. When comparing the parameters of the matching magnetic elements, it can be concluded that it is more appropriate to use a step-down autotransformer.
关键词： pulse-width modulation,magnetic elements,electronic phase shifting,rectifiers,power factor
更新于2025-09-23 15:22:29
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[IEEE 2020 7th International Conference on Signal Processing and Integrated Networks (SPIN) - Noida, India (2020.2.27-2020.2.28)] 2020 7th International Conference on Signal Processing and Integrated Networks (SPIN) - Active Power Filter for Harmonic Mitigation of Power Quality Issues in Grid Integrated Photovoltaic Generation System
摘要： Single phase tied with Photovoltaic arrangement (PV) employed on perturbed & observed (P&O) maximum energy point tracking technique with shunt active power filter allied to a rectifier feed R-L nonlinear load. The traditional Perturbed & Observed technique maximum energy point tracking topology is applied to attained maximum output power from Photovoltaic array(PVA), Proportional Integral conventional controller with phase detector (PLL) (PD) phase synchronization are executed to produce reference current. It provide at control unit of pulse width modulation topology( PWM) is utilized in inverter to get steady output voltage. Self supported DC bus PWM converter is regulated from PV array. In proposed architecture is minimized total harmonic pollution existing in supply current owing to power electronic load is (PEL). Total current harmonic pollution (THDi) factor obtain better than compensated using dynamic filter shunt active power filter (SAPF) and power compensation. Hence, reactive power (KVAR) is delivered through system decrease and active power (KW) enhance. The suggested scheme has been implemented by way of MATLAB/SIMULINK 2015(a) environment.
关键词： Pulse width Modulated (PWM) Converter,Proportional Integral controller,Maximum Power Point Tracking (P & O) Scheme,Shunt Active Power Filter (SAPF),Photovoltaic Array (PVA)
更新于2025-09-23 15:21:01
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A hybrid output multiport converter for standalone loads and photovoltaic array integration
摘要： Multiport converters (MPCs) are relatively recent power converter structures, which bestow the merits such as the omission of redundant power stages, centralized control, compact packaging, enhanced efficiency, improved reliability, and so on and have larger potential in domestic applications. They have the ability to amalgamate energy sources such as photovoltaic (PV) sources and battery storages, and can accommodate hybrid (ac and dc) domestic loads (bulbs, fans, induction stoves, and electric bike chargers). Hence, they can replace the conventional off-line uninterruptible power supplies, which are habitually used in domestic applications. The unique feature of MPCs is the ability to transfer the power between multiple sources and loads concurrently/independently. This article proposes cascaded sources switched tapping multi-level DC-link inverter (CSSTMLDCLI) involved hybrid loads MPC, which can integrate PV sources and feed above mentioned hybrid domestic loads. The involved novel seven level multilevel inverter structure, the CSSTMLDCLI has reduced component count to offer a high quality ac output, while the dc output is synthesized by a forward converter structure. The working principle of the CSSTMLDCLI along with the systematic design procedure is presented. The validity and effectiveness of the proposed converter are ratified through both MATLAB? Simulink R2016a simulation and the experimentation for a typical solar, battery, and grid supported domestic power backup. The system is managed for a lesser energy purchase using a developed minimal grid usage energy management system, which is implemented using ALTERA QUARTUS II 12.0SP2, field-programmable gate array processor.
关键词： hybrid load MPC (HLMPC),photovoltaic (PV),cascaded sources switched tapping multilevel DC-link inverter (CSSTMLDCLI),multilevel inverters (MLI),pulse width modulation (PWM),multiport converters (MPC)
更新于2025-09-23 15:21:01
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A High-Power-Factor Dimmable LED Driver with Integrated Boost Converter and Half-Bridge-Topology Converter
摘要： This paper proposes a dimmable light-emitting diode (LED) driver featuring a high power factor and zero-voltage switching on (ZVS). The circuit is obtained by integrating a boost converter and a dc-dc converter with half-bridge topology. The high power factor is achieved by operating the boost converter in discontinuous current mode (DCM). The LEDs are dimmed by the control scheme of asymmetrical pulse-width modulation (ASPWM). The developed circuit eliminates the inherited dc-o?set current of the transformer in a conventional asymmetrical half-bridge converter by introducing a balance capacitor. Both active switches can operate at ZVS by freewheeling the boost inductor current and the transformer magnetizing current to discharge the energy stored in their parasitic capacitance. The circuit operation is analyzed in detailed, and mathematical equations are derived. Finally, a 115-W prototype circuit for driving high brightness LEDs was built and tested. The experimental results verify the feasibility of the proposed LED driver with satisfactory performance. It can achieve a high power factor and ZVS operation.
关键词： power-factor correction,half-bridge converter,zero-voltage switching on (ZVS),asymmetrical pulse-width modulation (ASPWM),light-emitting diode (LED)
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - New designed electrode patterns on rear side of bifacial PERC solar cells
摘要： Present-day smartphones and tablets demand high audio fidelity (e.g., total harmonic distortion + noise, THD + N < 0.01%), and high noise immunity (e.g., power supply rejection ratio, PSRR > 80 dB) to allow high integration in an SoC. The design of conventional closed-loop pulse width modulation (PWM) Class-D amplifiers (CDAs) typically involves undesirable trade-offs between fidelity (qualified by THD + N), PSRR and switching frequency. In this paper, we propose a fully integrated CMOS CDA that embodies a novel input-modulated carrier generator and a novel phase-error-free PWM modulator, collectively allowing the employment of high loop-gain to achieve high PSRR, yet without compromising linearity/dynamic-range or resorting to high switching frequency. The prototype CDA, realized in 65 nm CMOS, achieves a THD + N of 0.0027% and a power efficiency of 94% when delivering 500 mW to an 8 ? load from VDD = 3.6 V. The PSRR of the prototype CDA is very high, –101 dB @217 Hz and 90 dB @1 kHz, arguably the highest to-date. Furthermore, the switching frequency of the prototype CDA varies from 320 to 420 kHz, potentially reducing the EMI due to spread-spectrum. In addition, the prototype CDA is versatile with a large operating-voltage range, with VDD ranging from rechargeable 1.2 V single battery to standard 3.6 V smart-device supply voltages.
关键词： Audio power amplifiers,power supply rejection ratio (PSRR),total harmonic distortion (THD),pulse width modulation (PWM),class D amplifiers
更新于2025-09-23 15:19:57
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Communication Compact CRLH Leaky-wave Antenna using TE20 Mode Substrate Integrated Waveguide for Broad Space Radiation Coverage
摘要： This paper introduces a combinational modulation method to be used in classic full-bridge single phase inverters. The proposed method eliminates even-order harmonics at the pulse width modulation (PWM) stage in the control section, unlike the conventional method of even order harmonic cancelation in the power stage, and offers a cost-effective design by switching one leg at high frequency. Using a low-cost digital signal controller platform, a regular sampling technique based on real-time calculation was employed to verify the feasibility of the proposed method on a 500-W single phase voltage source inverter. Performance characteristics, such as switching losses and harmonic distortions, are presented for the new approach and compared with a classic inverter modulation method.
关键词： switching frequency,Combinational logic circuits,inverters,pulse width modulation (PWM),silicon carbide,harmonic distortion
更新于2025-09-23 15:19:57