Sinusoidal Voltage Excitation Research Articles

초음파 진동절삭기의 펄스폭변조 가진 특성

To obtain an elliptical trajectory at the cutting edge during elliptical vibration cutting, sinusoidal voltage excitations of two piezoelectric actuators have commonly been used. In this study, PWM excitation, which is relatively simple to generate, was employed and its characteristics were investigated. In experimental and analytical analyses, we found that for PWM excitation, the integer-multiple frequencies of the excitation voltage distorted the shape of the elliptical trajectory, whereas at a duty ratio(DR) of 50%, the distortion of the elliptical trajectory was minimized due to disappearance of the first overtone. When the magnitude of the maximum excitation voltage was maintained at the same level for both PWM and sinusoidal excitation, PWM (DR=50%) excitation produced a greater vibration amplitude than sinusoidal excitation but resulted in more rapid saturation of a high-frequency power amplifier.

Transient Performance Analysis of Induction Motor Using Field-Circuit Coupled Finite-Element Method

In this paper, the application of field-circuit coupled finite-element method for predicting the performance of induction motor (IM) under a sinusoidal voltage excitation is described. The numerical analysis is performed by solving the nonlinear time-stepping finite-element equations coupled with the circuit equations and mechanical motion equations. The circuit equations are described by means of improved nodal method. The local analytical solution of Laplace equation is used to improve the precision of electromagnetic torque. The performances of both three- and single-phase IMs are simulated using the developed field-circuit coupled code. The comparison among the results calculated by the code, the commercial FE package, FLUX 2-D, and the experiment results suggests the correctness of the field-circuit coupled method and related developed code.

Discharge Characteristics of an Atmospheric Pressure Argon Plasma Jet Generated with Screw Ring-Ring Electrodes in Surface Dielectric Barrier Discharge

An atmospheric-pressure argon plasma jet with screw ring-ring electrodes in surface dielectric barrier discharge is generated by a sinusoidal excitation voltage at 8 kHz. The discharge characteristics, such as rotational and vibrational temperature of nitrogen, electronic excitation temperature, oxygen atomic density, nitrogen molecular density, and average electron density, are estimated. It is found that the rotational temperature of nitrogen is in the range of 352 ∼ 392 K by comparing the simulated spectrum with the measured spectrum at the C3Πu → B3Πg(Δv = −2) band transition, the electronic excitation temperature is found to be in the range of 3127 ∼ 3230 K by using the Boltzmann plot method, the oxygen atomic and nitrogen molecular density are of the order of magnitude of 1016 cm−3 by the actinometry method, and the average electron density is of the order of magnitude of 1012 cm−3 by the energy balance equation. Besides, the effective power, conduction, and displacement current are measured during the discharge.

FEA Aided Design of Power Shunt-Reactors with Discretely-Distributed Air-Gaps

In this paper, a Finite Element Analysis (FEA) aided design methodology for power shunt-reactors is proposed. The lack of simple and straightforward expressions for the calculation of gap-loss component and leakage inductance is the bottleneck of a fully analytical design procedure. To tackle with the difficulty arising from the calculation of gap-loss, the total air-gap is subdivided into several discretely-distributed air-gaps. This makes the gap-loss component negligibly small in comparison with the core loss. The preliminary design of the target reactor can therefore be achieved analytically by using an initial estimate of percentage leakage inductance. The preliminary design can then be tested and fine-tuned by using Maxwell 3D Magnetostatic Excitation and 2D Transient Sinusoidal Current Excitation tools,in the second phase of the recommended design procedure. The reactor under design can be optimized according to one of minimum Initial Cost, minimum Total Loss or minimum Present Value Cost design objectives, upon the request of the customer or the designer. Advantages and disadvantages of Maxwell 3D and 2D Transient Sinusoidal Current Excitation and Transient Sinusoidal Voltage Excitation analyses facilities are also discussed in the paper

Oxygen atomic density of atmospheric Ar plasma jet generated with syringe needle-ring electrodes

Atmospheric-pressure argon plasma jet is generated with syringe needle-ring electrodes in an 8 kHz sinusoidal excitation voltage. It is found that the rotational temperature of nitrogen is in the range of 333 – 373 K obtained by comparing the simulated spectrum with the measured spectrum at the C3Πu → B3Πg (Δv = −2) band transition, the electronic excitation temperature is in the range of 3187 – 3243 K determined by the Boltzmann's plot method, and the oxygen atomic density is in the order of magnitude of 1016 cm−3 estimated by the actinometry method, respectively.

Electrical and Spectral Characteristics of a Low-Temperature Argon–Oxygen Plasma Jet With Syringe Needle-Ring Electrodes

Low-temperature atmospheric-pressure argon–oxygen plasma jet is generated with syringe needle-ring electrodes, which is powered by a sinusoidal excitation voltage at 8 kHz. The volume percentage of the oxygen content in the argon gas is as high as 12.5%. It is found that the rotational temperature of nitrogen is in the range of 297–320 K, and the vibrational temperature is almost unchanged to be about 2475 K, which is obtained by comparing the simulated spectrum with the measured spectrum at the <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$C^{3} \Pi_{u} \rightarrow B^{3}\Pi_{g}\ (\Delta v = -2)$</tex></formula> band transition. The electronic excitation temperature is in the range of 8587–8994 K as obtained by the Boltzmann's plot method, the electron temperature at the tip of syringe needle is about 7.3 eV as estimated by the Einstein's equation, and the densities of atomic oxygen and molecular nitrogen are, respectively, on the order of magnitude of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$10^{16}\ \hbox{cm}^{-3}$</tex></formula> as determined by actinometry method, respectively. Moreover, the 2-D and 1-D distributions of the electric field magnitude are estimated by the 2-D finite-element software. At a time of 45.7 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\mu\hbox{s}$</tex></formula> and an instantaneous applied voltage of 8 kV, the electric field magnitude at the edge of the ring ground electrode is the largest, and it is 15.9 kV/cm at the tip of the syringe needle.

Electrical and spectral characteristics of an atmospheric pressure argon plasma jet generated with tube-ring electrodes in surface dielectric barrier discharge

An atmospheric-pressure argon plasma jet is generated with tube-ring electrodes in surface dielectric barrier discharge by a sinusoidal excitation voltage at 8kHz. The electrical and spectral characteristics are estimated such as conduction and displacement current, electric-field, electron temperature, rotational temperature of N2 and OH, electronic excitation temperature, and oxygen atomic density. It is found that the electric-field magnitudes in the top area of the ground electrode are higher than that in the bottom area of the power electrode, and the electron temperature along radial direction is in the range of 9.6–10.4eV and along axial direction in the range of 4.9–10eV. The rotational temperature of N2 obtained by comparing the simulated spectrum with the measured spectrum at the C3Πu→B3Πg(Δv=−2) band transition is in the range of 342–387K, the electronic excitation temperature determined by Boltzmann's plot method is in the range of 3188–3295K, and the oxygen atomic density estimated by the spectral intensity ratio of atomic oxygen line λ=844.6nm to argon line λ=750.4nm is in the order of magnitude of 1016cm−3, respectively.

Characteristic study of cold atmospheric argon plasma jets with rod-tube/tube high voltage electrode

Abstract Atmospheric argon plasma jets are generated with the rod-tube/tube high voltage electrode and a ring ground electrode at 8 kHz sinusoidal excitation voltage. It is found that the vibrational temperature, electronic excitation temperature, atomic oxygen density and spectral intensity with the rod-tube high voltage electrode are enhanced significantly than that with the tube high voltage electrode. The atomic oxygen density, molecular nitrogen density, and average electronic density are about magnitude of 10 16 cm −3 , 10 15 cm −3 , and 10 12 cm −3 respectively, and the excited Ar, N 2 , OH and O are presented in the plasma plume with the rod-tube/tube high voltage electrode.

Study on the Influence of Dielectric Barrier Materials on the Characteristics of Atmospheric Plasma Jet in Ar

In this paper, an Ar plasma jet is generated under atmospheric pressure using a DBD configuration device equipped with a copper-ring powered electrode as well as an aluminous plate ground electrode, which is driven by a sinusoidal excitation voltage at 10 kHz, and three types of dielectric barriers, i.e., quartz glass, epoxy, and PTFE, are employed to study the influence of the barrier materials on the characteristics of the plasma jet. The jet characteristics are studied by electrical and optical diagnostics, and the voltage-current waveforms, Lissajous figures, lighting emission images, and optical spectrum are obtained. The electric discharge parameters and plasma parameters, such as discharge power, transported charges, electronic excitation temperature, etc., are calculated and compared by using different dielectric barriers, and the mechanism of the influence of the barrier material on the jet discharge is discussed. The experimental results show that the influence of the barrier materials on the characteristics of the plasma jet is related not only to the relative dielectric constant but also to the desorption of surface electrons from them. Under the same operation conditions, more intensive jet discharge can be obtained by using PFTE as the barrier material, and the discharge power, transported charges, and electronic excitation temperature are higher than those of quartz glass and epoxy as dielectric barriers.

Optical and Electrical Diagnostics of Cold Ar Atmospheric Pressure Plasma Jet Generated With a Simple DBD Configuration

A cold Ar atmospheric pressure plasma jet generated using a DBD configuration device equipped with two powered electrodes as well as a grounded ring electrode driven by a sinusoidal excitation voltage at 38 kHz is presented in this paper. In this paper, properties of the jet discharge are studied by electrical diagnostics, including applied voltage, conducting current, and average absorbed power. Moreover, the optical emission spectroscopy is used to measure the plasma parameters, of which the electronic excitation temperature is determined by the Boltzmann's plot method using ten characteristic lines of Ar from 3p54p → 3p54s and 3p55p → 3p54s transitions whereas the gas temperature is obtained by using a fiber thermometer (FISO FOT-L-SD). It has been found that the conducting current, average absorbed power, the excitation temperature, and gas temperature increase with the applied voltage. On the other hand, these parameters are inversely proportional to the argon gas flow rate. What is more is that the production of oxygen radical (produced by the collisions between oxygen molecule from atmosphere and high-energy particles in plasma effluent) at a gas flow rate of 2 slm is investigated by means of optical actinometry, which is found to increase with the applied voltage.

Enhanced performance of an EUV light source (λ = 84 nm) using short-pulse excitation of a windowless dielectric barrier discharge in neon

The electrical and optical characteristics of a dielectric barrier discharge (DBD) based neon excimer lamp generating output in the extreme ultraviolet (EUV) spectral range (λ = 84 nm) have been investigated experimentally. We report a detailed comparison of lamp performance for both pulsed and sinusoidal voltage excitation waveforms, using otherwise identical operating conditions. The results show that pulsed voltage excitation yields a ∼50% increase in the overall electrical to EUV conversion efficiency compared with sinusoidal waveforms, when operating in the pressure range 500–900 mbar. Pulsed operation allows greater control of parameters associated with the temporal evolution of the EUV pulse shapes (risetime, instantaneous peak power). The Ne DBD based source is also found to be highly monochromatic with respect to its spectral output from the second continuum band at λ ∼ 84 nm (5 nm FWHM). This continuum band dominates the spectral emission over the wavelength range 30–550 nm. Lamp performance; as measured by the overall EUV output energy, electrical to EUV conversion efficiency and spectral purity at λ ∼ 84 nm; improves with increasing gas pressure up to p = 900 mbar.

High frequency excitation waveform for efficient operation of a xenon excimer dielectric barrier discharge lamp

The application of a high frequency (∼2.5 MHz) burst (amplitude-modulated sinusoidal) excitation voltage waveform is investigated for driving a fluorescent dielectric barrier discharge (DBD) light source. The excitation waveform presents a novel method for generating spatially stable homogeneous Xe DBD possessing a high conversion efficiency from electrical energy to VUV excimer radiation (∼172 nm), even at a significantly higher electrical energy deposition than realized by pulsed excitation. Simulation and experimental results predict discharge efficiencies around 60%. Lamp efficacy above 74 lm W−1 has been achieved. VUV emission and loss mechanisms are investigated extensively and the performance of burst and pulsed waveforms is compared both theoretically and experimentally.

Improved GMI Sensors Using Strongly-Coupled Thin Pick-Up Coils

The performance of Giant Magneto-Impedance (GMI)-based magnetometers is currently limited by electronics, particularly as regards the equivalent magnetic noise. Thus, it is crucial to increase the sensitivity before demodulation. With that objective, we analyze one solution, using a wire-wound device, consisting of a very thin pick-up coil wrapped around a GMI wire, as a sensing element. We present an electrical sensor model using classical two-port network impedance parameters. It allows us to predict the expected improvement in sensitivity, simulating the device implementation in an appropriate electronic design. Preliminary results suggest an improvement in sensitivity by a factor 2 for a 0 dBm sinusoidal excitation voltage source at 10 MHz. Noise measurements support this analysis and show an intrinsic output magnetic noise improvement in the same ratio.

Measurement of magnetic losses by thermal method applied to power ferrites at high level of induction and frequency

Classically, low frequency losses in soft magnetic materials and ferrites in particular are measured by flux metric method under sinusoidal waveform excitation voltage. However, in typical application of modern power electronics, the frequency currently exceeds 100 kHz. This feature is at the origin of a difficulty: the phase shift between current and voltage can be disturbed by current probe delay. Thus, the results can be affected by large errors. As a consequence, it becomes more and more important to develop alternative methods to measure losses in magnetic materials. It is proposed to use calorimetric method which is by principle free of the above mentioned problems. The experimental device is described in details and the results are reported for experiments conducted on a commercial Mn-Zn ferrite under sinusoidal waveform regime for frequencies varying from 10 to 200 kHz. Comparisons with flux metric measurement show that significant differences appear typically for Bf products above 5000 V/m(2) (50 kHzx100 mT).

Magneto-Mechanical Resonance in a Model 3-Phase 3-Limb Transformer Core Under Sinusoidal and PWM Voltage Excitation

This investigation presents the measurement results of acoustic noise and vibration of a model three-phase three-limb transformer core under sinusoidal and PWM voltage excitation for assigned value of modulation index with switching frequency from 1 kHz to 3 kHz at no-load condition. Results show that the acoustic noise decreased around 2 (dBA) with increasing switching frequency. However, magneto-mechanical resonance phenomenon was observed at 3 kHz vibration frequency, which could cause excess acoustic noise under some excited conditions.

Size Effect on the Thermal Conductivity of Thin Metallic Films Investigated by Scanning Joule Expansion Microscopy

A technique to extract in-plane thermal conductivity of thin metallic films whose thickness is comparable to electron mean free path is described. Microscale constrictions were fabricated into gold films of thicknesses 43nm and 131nm. A sinusoidal voltage excitation across the constriction results in a local temperature rise. An existing technique known as scanning joule expansion microscopy, measures the corresponding periodic thermomechanical expansion with a 10nm resolution and determines the local temperature gradient near the constriction. A three-dimensional finite-element simulation of the frequency-domain heat transfer fits the in-plane thermal conductivity to the measured data, finding thermal conductivities of 82±7.7W∕mK for the 43nm film and 162±16.7W∕mK for the 131nm film, at a heating frequencies of 100kHz and 90kHz, respectively. These values are significantly smaller than the bulk thermal conductivity value of 318W∕mK for gold, showing the electron size effect due to the metal-dielectric interface and grain boundary scattering. The obtained values are close to the thermal conductivity values, which are derived from electrical conductivity measurements after using the Wiedemann–Franz law. Because the technique does not require suspended metal bridges, it captures true metal-dielectric interface scattering characteristics. The technique can be extended to other films that can carry current and result in Joule heating, such as doped single crystal or polycrystalline semiconductors.

Flexible Arrays of Ni/Polyimide/Cu Microplasma Devices with a Dielectric Barrier and Excimer Laser Ablated Microcavities

Microcavity plasma devices with circular, crescent or, for example, trapezoidal cross-section microcavities (characteristic dimension d=30–100 µm), produced by excimer laser ablation and overcoated with a silicon nitride barrier film, have been fabricated in Ni/30 µm polyimide/3 µm Cu layered substrates. 12×12 arrays of devices with cylindrical microcavities 100 µm in diameter exhibit turn-on voltages of 255–270 Vrms for a Ne pressure of 700 Torr and a sinusoidal excitation voltage having a frequency of 5–20 kHz. All of the device designs explored to date operate in the abnormal glow region, and an increase of 15–20% in the ignition voltage for these arrays is observed when pd is raised from 4 to 5 Torr cm. Tests in which the arrays were intentionally damaged or photoablation parameters were altered from the optimal values show the microplasma devices to be extraordinarily robust and insensitive to the cross-sectional shape of the microcavity.

Measurement of dynamic magnetic loss parameter in ferrites

The measurement of the iron loss in ferrites is important for developing high-efficiency switching power supplies. The authors have proposed the dynamic magnetic loss parameter, λf, for evaluating the iron loss in ferrites. In previous studies, the parameter was assumed to be a constant value for an individual ferrite material and defined for one period of a small B–H loop. In this paper, assuming that λf is a function of the time derivative of the magnetic flux density, dB/dt, a novel measurement method of λf of a Ni-Zn ferrite is proposed using rectangular wave voltage excitation and the Fourier expansion of the exciting current. In order to realize an iron loss measurement system with the rectangular wave voltage excitation, a high-frequency FET inverter has been developed. The results of measuring λf show that it is uniquely determined by dB/dt regardless of the B–H loop size. The measured dB/dt characteristics of λf are applied to practical examples for switching power supplies and sinusoidal wave voltage excitations. Their experimental and computational results coincide and it is clarified that the measured dB/dt characteristics are effective and useful. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(1): 1–6, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20101

Localised losses in stator laminations of an induction motor under PWM excitation

Electronically generated voltage waveforms have increasingly been used to energise small induction motors for speed and torque control due to low cost. The most popular such waveform is a pulse width modulation (PWM), which is obtained by logically comparing a reference voltage waveform with a carrier wave of different frequency. When a small induction motor is driven by a typical PWM voltage supply, additional power losses occur in its stator core due to a magnetisation process, which is very different to standard sine wave excitation. In this investigation flux density and power loss distribution under PWM and sinusoidal voltage excitations were measured in a small induction motor stator core using a system which set up flux distribution as would occur in a rotating 3-phase stator core. The iron loss increase was between 15 and 20% under PWM excitation. Surprisingly, the increase in iron loss in a typical induction motor stator core lamination was 3% lower than that in Epstein strips of the same electrical indicating an effect of the magnetic circuit geometry as well as the voltage waveform.

Measurements of power loss distribution in a typical stator core under PWM voltage excitation

The pulse width modulated (PWM) inverter is widely used to feed small induction motors for variable speed and torque control. When a laminated stator core is energised in this way additional iron losses occur due to localised distorted flux. Flux density and power loss distribution under PWM and sinusoidal voltage excitations were measured in a typical induction motor stator core lamination at 1.3 T, 50 Hz by using a computer-aided magnetising system to set up flux distribution as would occur in a practical three-phase stator core. The iron loss increased 15–20% under PWM excitation. The loss increase under PWM excitation in the stator core laminations was 3% lower than in Epstein strips of the same electrical steel under the same conditions showing an effect of the magnetic circuit geometry.