Showing papers on "Sine wave published in 2016"

High-Efficiency Bidirectional DAB Inverter Using a Novel Hybrid Modulation for Stand-Alone Power Generating System With Low Input Voltage

Abstract: This paper proposes a high-efficiency bidirectional dual-active-bridge (DAB) inverter using a novel hybrid modulation for a stand-alone power generating system with a low input voltage. The proposed DAB inverter consists of a DAB dc–dc converter and a synchronous rectifier (SR) for unfolding. The DAB dc–dc converter transforms the low dc voltage into a rectified sine wave that pulsates twice the grid frequency. The rectified sine wave unfolds into the grid voltage by SR. The proposed hybrid modulation combines a phase shift control and a variable frequency control. The variable frequency control converts the nonlinear function of the phase shift angle into a linear function and controls the output power. This leads to a simple closed-loop control for the sinusoidal current waveform, a low harmonic distortion, and a high-voltage conversion ratio without an increase of the transformer turn ratio. Since the proposed DAB inverter has only a single power conversion stage, it has a simple structure, high power density, and low cost. It also has a high efficiency of 94.2% by a zero-voltage switching (ZVS) turn on of the switches in two full bridges (FBs). The operation principle of the proposed DAB inverter using this hybrid modulation is analyzed and verified. Experimental results for a 1-kW prototype are obtained to show the performance.

A Kalman Filter for Amplitude Estimation in High-Speed Dynamic Mode Atomic Force Microscopy

Abstract: A fundamental challenge in dynamic mode atomic force microscopy (AFM) is the estimation of the cantilever oscillation amplitude from the deflection signal, which might be distorted by noise and/or high-frequency components. When the cantilever is excited at resonance, its deflection is typically obtained via narrow-band demodulation using a lock-in amplifier (LIA). However, the bandwidth of this measurement technique is ultimately bounded by the low-pass filter, which must be employed after demodulation to attenuate the component at twice the carrier frequency. Furthermore, to measure the amplitude of multiple frequency components, such as higher eigenmodes and/or higher harmonics in multifrequency AFM, multiple LIAs must be employed. In this paper, the authors propose the estimation of amplitude and phase using a linear time-varying Kalman filter that is easily extended to multiple frequencies. Experimental results are obtained using square-modulated sine waves and closed-loop AFM scans, verifying the performance of the proposed Kalman filter.

Propagation of extensional waves in a piezoelectric semiconductor rod

Abstract: We studied the propagation of extensional waves in a thin piezoelectric semiconductor rod of ZnO whose c-axis is along the axis of the rod. The macroscopic theory of piezoelectric semiconductors was used which consists of the coupled equations of piezoelectricity and the conservation of charge. The problem is nonlinear because the drift current is the product of the unknown electric field and the unknown carrier density. A perturbation procedure was used which resulted in two one-way coupled linear problems of piezoelectricity and the conservation of charge, respectively. The acoustic wave and the accompanying electric field were obtained from the equations of piezoelectricity. The motion of carriers was then determined from the conservation of charge using a trigonometric series. It was found that while the acoustic wave was approximated by a sinusoidal wave, the motion of carriers deviates from a sinusoidal wave qualitatively because of the contributions of higher harmonics arising from the originally n...

Single actuator wave-like robot (SAW): design, modeling, and experiments

Abstract: In this paper, we present a single actuator wave-like robot, a novel bioinspired robot which can move forward or backward by producing a continuously advancing wave. The robot has a unique minimalistic mechanical design and produces an advancing sine wave, with a large amplitude, using only a single motor but with no internal straight spine. Over horizontal surfaces, the robot does not slide relative to the surface and its direction of locomotion is determined by the direction of rotation of the motor. We developed a kinematic model of the robot that accounts for the two-dimensional mechanics of motion and yields the speed of the links relative to the motor. Based on the optimization of the kinematic model, and accounting for the mechanical constraints, we have designed and built multiple versions of the robot with different sizes and experimentally tested them (see movie). The experimental results were within a few percentages of the expectations. The larger version attained a top speed of 57 cm s(-1) over a horizontal surface and is capable of climbing vertically when placed between two walls. By optimizing the parameters, we succeeded in making the robot travel by 13% faster than its own wave speed.

Stochastic Analysis of an Adaptive Line Enhancer/Canceler With a Cyclostationary Input

Abstract: This paper studies the second moment behavior of the adaptive line enhancer (ALE)/adaptive line canceler (ALC) for a cyclostationary input consisting of a fixed amplitude random phase sine wave plus a white Gaussian process with periodic power variations. Both transient and steady-state results are shown to be in good-to-excellent agreement with Monte Carlo simulations. The main conclusion is that periodic input power variations cause periodic processing gain variations of the ALE/ALC with the same period as the input power. However, these variations do not cause a large degradation in the ALE/ALC performance.

Frequency-time coherence for all-optical sampling without optical pulse source.

Abstract: Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift.

An Altered PWM Scheme for Single-Mode Seamless Control of AC Traction Motors for Electric Drive Vehicles

Abstract: In an electric drive vehicle (EDV), the available voltage on a dc-link is limited, and so the inverter output voltage and, consequently, the line motor maximum speed are limited. The fundamental voltage of the inverter output is increased approximately 27% using a square wave (SW) switching pattern instead of a sine wave switching pattern. However, this pattern can only be used at high speeds, and at lower speeds a pulsewidth modulation (PWM) pattern should be used. In order to achieve proper control, the switching pattern should be changed seamlessly. In the present paper, a new PWM scheme for single-mode seamless control of Vernier motors is proposed. In the proposed scheme, the reference voltage is modified to change the switching pattern continuously so that the voltage changes smoothly from a high-frequency pattern to an SW and voltage discontinuity does not occur. Experimental results reveal that the inverter-switching pattern changes smoothly from a sinusoidal PWM pattern to an SW pattern, and so seamless control from the constant-torque region to the constant-power region, and vice versa, is achieved. Since the proposed scheme is a single-mode control, it is much simpler than current technologies, which are based on multimode controllers. Also the proposed method has a lower total harmonic disturbance (THD) as well as a lower harmonic distortion factor (HDF) compared to some existing methods.

Photonic-assisted time-interleaved ADC based on optical delay line

Abstract: An approach to implement photonic-assisted time-interleaved analog-to-digital conversion and its calibration method are presented. The analog modulated optical signal is divided into M channels, suffering different time delay induced by optical delay lines which provide great flexibility in producing time intervals and is then sampled by electronic analog-to-digital converters (ADCs). The channel mismatches resulting in performance degradation are estimated by a modified sine wave fitting method. The time mismatch and other mismatches are corrected by fine optical delay adjustment and digital processing, respectively. A four-channel photonic-assisted time-interleaved analog-to-digital converter (TIADC) system operating at 40 GSa s−1 was demonstrated experimentally. The photonic-assisted TIADC system was tested with a 6.31 GHz sine wave signal, exhibiting 40.3 dB signal-to-noise and distortion ratio (SINAD) and 57.6 dBc spurious-free dynamic range (SFDR). It is shown that the SINAD is dominated by the signal-to-noise ratio (SNR) of the analog optical link and the SFDR of the proposed system is limited by the linearity of the link.

High-velocity operation of piezoelectric inertia motors: experimental validation

Abstract: Piezoelectric inertia motors use the inertia of a body to drive it by means of a friction contact in a series of small steps. It has been shown previously in theoretical investigations that higher velocities and smoother movements can be obtained if these steps do not contain phases of stiction (“stick-slip” operation), but use sliding friction only (“slip-slip” operation). One very promising driving option for such motors is the superposition of multiple sinusoidal signals or harmonics. In this contribution, the theoretical results are validated experimentally. In this context, a quick and reliable identification process for parameters describing the friction contact is proposed. Additionally, the force generation potential of inertia motors is investigated theoretically and experimentally. The experimental results confirm the theoretical result that for a given maximum frequency, a signal with a high fundamental frequency and consisting of two superposed sine waves leads to the highest velocity and the smoothest motion, while the maximum motor force is obtained with signals containing more harmonics. These results are of fundamental importance for the further development of high-velocity piezoelectric inertia motors.

Method for controlling brittleness Laves phases in laser additive manufacturing process of nickel-based high-temperature alloy

Abstract: The invention discloses a method for controlling brittleness Laves phases in the laser additive manufacturing process of a nickel-based high-temperature alloy. Firstly, laser additive manufacturing technological parameters are initially optimized, and a cooling medium is adopted for cooling the bottom of a base material; then a laser modulation technology is used for modulating a laser source, and superior laser modulation parameters are obtained, wherein the peak power of square waves ranges from 600 W to 1000 W, the pulse frequency of the square waves ranges from 10 HZ to 100 HZ, and the duty ratio of the square waves ranges from 0.3 to 0.6; the wave peak power of sawtooth waves ranges from 600 W to 1200 W, the wave trough power of the sawtooth waves is 0 W, and the pulse frequency of the sawtooth waves ranges from 10 HZ to 100 HZ; and according to the parameters of sine waves, the wave peak power ranges from 600 W to 1000 W, the wave trough is 0 W, and the pulse frequency ranges from 10 HZ to 100 HZ; and finally, laser additive manufacturing and forming of the nickel-based high-temperature alloy are conducted according to the above parameters, and a formed part with all small equiaxial dendritic structures and small discrete Laves phases is obtained. By means of the laser modulation method, the precipitation behavior of the Laves phases in the laser additive manufacturing process of the nickel-based high-temperature alloy can be effectively controlled, the cracking sensibility of parts obtained through laser additive manufacturing is reduced, and the microstructure is improved.

Analysis and modeling of a proportional directional valve with nonlinear solenoid

Abstract: To explain the influence of the nonlinear characteristic of a proportional directional valve with double solenoids, a dynamic model with a nonlinear performance in current–force–displacement of double solenoids proportional valve is presented. Despite the analyzing of nonlinear characteristic of the solenoids, the valve spool modeling, the orifice area and the dynamic model of the valve are also presented. The simulation model is set in MATLAB and a test rig is built for the dynamic performance test. At last, the comparison in sine wave and dynamic response of the simulation and the experiments are made. A big distortion occurs near zero spool position because the nonlinear characteristic is mainly manifested when the solenoid current is small. And it is mainly induced by the nonlinear characteristic of the solenoids and the direction switch motion of spool. The output in simulation is almost coincided with that of experimental result. That means the proposed modeling method of solenoids and valve is valid and effective. Some advanced control theories and methods can be applied simultaneously.

Properties of proprioceptive sensation with a vibration speaker-type non-grounded haptic interface

Abstract: This paper describes the properties of sensations induced by a vibration speaker-type non-grounded haptic interface. We confirm that the vibration speaker generates a perceived force that pulls or pushes a user's hand in a particular direction when an asymmetric amplitude sound signal that is generated by inverting a part of a sine wave is input. We developed a prototype system and conducted evaluation experiments to evaluate the induced proprioceptive sensations. As a result, we confirmed that the system was able to control both the direction and magnitude of the reaction force by changing the input signal.

Gain-compensated sinusoidal scanning of a galvanometer mirror in proportional-integral-differential control using the pre-emphasis technique for motion-blur compensation

Abstract: We propose a method to achieve precise sine-wave path tracking for real-time motion-blur compensation to extend the corresponding frequency spectrum in proportional-integral-differential (PID) control by using a pre-emphasis technique. We calculate pre-emphasis coefficients in advance to follow a sine wave with a gain of 0 dB and multiply the input signal by these pre-emphasis coefficients. In experiments, we were thus able to extend the greatest frequency from 100 to 500 Hz and achieve gain improvement of approximately 3 dB at 400 and 500 Hz. For the application of inspection, we confirmed that motion blur is significantly reduced when the system operates at high frequency, and we achieved a responsiveness 3.3 times higher than that of our previous system.

Optimization and performance improvement of an electromagnetic-type energy harvester with consideration of human walking vibration

Abstract: In this study, we derived an equation of motion for an electromechanical system in view of the components and working mechanism of an electromagnetic-type energy harvester (ETEH). An electromechanical transduction factor (ETF) was calculated using a finite-element analysis (FEA) based on Maxwell’s theory. The experimental ETF of the ETEH measured by means of sine wave excitation was compared with and FEA data. Design parameters for the stationary part of the energy harvester were optimized in terms of the power performance by using a response surface method (RSM). With optimized design parameters, the ETEH showed an improvement in performance. We experimented with the optimized ETEH (OETEH) with respect to changes in the external excitation frequency and the load resistance by taking human body vibration in to account. The OETEH achieved a performance improvement of about 30% compared to the initial model.

A Switch-Based Interpolated DFT for the Small Number of Acquired Sine Wave Cycles

Abstract: The frequency of a real sinusoid is often estimated by interpolated discrete Fourier transform (IpDFT) algorithms because of the high accuracy and low computational burden. However, conventional IpDFTs focus on frequency estimation when the number of acquired sine wave cycles (NASC) is more than two. Frequency estimation with the small NASC is applicable in manufacturing processes, radar level measurement, and other applications. The spectral leakage of the negative frequency (the image component) significantly distorts the positive frequency when the NASC is small, dramatically degrading estimation accuracy. In particular, it is a challenging task for existing IpDFTs to provide high estimation accuracy when the NASC is less than one. In this paper, a switch-based IpDFT is proposed to provide high frequency estimation accuracy for $\text {NASC} . The theoretical variance of the algorithm in white Gaussian noise is formulated, which includes the upper bound and the lower bound. Computer simulations and real measurements are conducted to corroborate the theoretical analysis and to demonstrate that the proposed algorithm achieves better accuracy and antinoise capability for $\text {NASC} than existing algorithms.

Tilt sensor based on three electrodes dielectric liquid capacitive sensor

Abstract: This paper presents a design, fabrication and characterization of a low-cost capacitive tilt sensor. The proposed sensor consists of a three-electrode capacitor, which contains two-phase of the air and liquid as the dielectric media. The three electrodes hold a plastic tube and the tube is positioned on a printed circuit board (PCB) which consists of a 127 kHz sine wave generator, a pre-amplifier, a rectifier and a low pass filter. The proposed sensor structure can measure tilt angles in the rage of 0° to 75°, where the linear relationship between the angle to be measured and the output signal was observed in the range of 0° to 50°. The sensitivity and resolution of the sensor are measured to be 40mV/degree and 0.5 degree, respectively.

Accurate spectral testing with non-coherent sampling for large distortion to noise ratios

Abstract: Spectral testing is widely used in characterizing the dynamic performance of analog signals. Achieving accurate test results is an expensive and challenging task. This paper focuses on eliminating the challenging requirement of non-coherent sampling in the presence of an impure signal with large distortion to noise ratios. A new method was proposed that iteratively estimated noncoherent fundamental and harmonics. Comparisons are made with several widely used methods: windowing, 4 parameter sine wave fitting, and FIRE method, to address the need for this new method. They are quantitatively examined for robustness at different input signal purity and non-coherency level. The advantages & limitations of these methods are discussed. Extensive simulation results show the effectiveness and robustness of the proposed method, which can tolerate wide range of signal purity and any level of non-coherency. It can be implemented for on-chip accurate spectral test, and can also be suitable for accurate ADC spectrum test when the pure source is not available.

Online electrochemical impedance spectroscopy detecting system and method of fuel cell

Abstract: The invention relates to internal resistance detection of a fuel cell, specially an online electrochemical impedance spectroscopy detecting system and method of the fuel cell. The excitation source of the system is integrated in a Boost circuit, the excitation source is unnecessary to generate triangular waves in the whole process, the Boost circuit controls the fuel cell current to generate the current formed by superimposing direct current and slight triangular waves not influencing the work of the cell, after the work of the fuel cell is stabilized, Fourier analysis is carried out to the voltage and the current of the fuel cell; the internal resistance value of the fuel cell under every frequency is obtained, and the electrochemical impedance spectroscopy of the cell is obtained. With respect to the given triangular waves of the system, the triangular waves of three frequencies are given successively by a selection mode so as to be convenient in measurement; with respect to the control of the current, the current of the cell is controlled by prediction control; the whole system overcomes the defect of the design of the excitation source and the defect that the frequency scanning time of using sine waves is long.

Pulse-type fitness-massage constant-temperature water-bed with data control and analysis

Abstract: The invention discloses a pulse-type fitness-massage constant-temperature water-bed with data control and analysis. A water-filled mattress is provided with a magnetic disk pulsator and a sine wave gear surface pulsator, and is connected with a liquid inlet of a magnetic cylinder differential circulating pump through an air-source hot water barrel; the liquid outlet of the magnetic cylinder differential circulating pump is communicated with the water-filled mattress through a pipeline; and the air source hot water barrel is connected with an air source host. The pulse-type fitness-massage constant-temperature water-bed has the working principles and effects in sine wave gear surface differential vibration source, magnetic disk differential magnet attracted and repelled vibration source and magnetic cylinder differential magnet attracted and repelled water-circulating pulse pump beyond expectation of technicians in the field; intelligent control is carried out by data control and analyzer, so that temperature constancy and regulation can be realized; and pulse can be combined and optimized to realize intelligent fitness, and the fitness-massage requirement of high-end users can be met. The water-bed has a wide market prospect.

Optimization of a digital lock-in algorithm with a square-wave reference for frequency-divided multi-channel sensor signal detection.

Abstract: A digital lock-in detection technique is commonly used to measure the amplitude and phase of a selected frequency signal. A technique that uses a square wave as the reference signal has an advantage over the one using a sinusoidal wave due to its easier implementation and higher computational efficiency. However, demodulating multiple-frequency composite signals using square wave reference may result in interference between channels. To avoid interference between channels and reduce the computational complexity, we modify the calculations and determine the optimal parameter settings of the low-pass filter and carrier frequency, as detailed in this paper. The results of our analysis show that when the length of the average filter and carrier frequencies are properly set, the interference between the channels is removed. This optimization produces the digital lock-in detection suitable for measuring multi-channel sensor signals.

Motor driving device and motor system

Abstract: The phase of a drive current of a motor is optimized. The phase arithmetic unit PHCAL calculates a drive voltage phase θdrv to converge the phase difference between the reference voltage phase θbemf and the reference current phase θi to zero based on a prescribed arithmetic expression. The phase correction unit PHCP determines the phase θdrvR after the correction by adding a correction value to the phase θdrv, and the magnitude of the correction value is updated by a feedback control so as to converge to a prescribed value the phase difference between the reference voltage phase θbemf and the reference current phase θi which are inputted. A PWM controller shifts an energization control timing synchronized with the reference voltage phase θbemf based on the corrected phase θdrvR, and generates the PWM signal for controlling the drive voltage to a sine wave shape.

Examination verification apparatus of high-frequency-current-method partial discharge detector and method thereof

Abstract: The invention discloses an examination verification apparatus of a high-frequency-current-method partial discharge detector and a method thereof. The apparatus comprises a signal excitation source, a matching resistor R0, an injection capacitor C0, a first metal test rod, a second metal test rod, an oscilloscope and a 50omega coaxial cable. A detected apparatus comprises a partial discharge detector and a high frequency sensor. The signal excitation source is a built-in signal source of the apparatus and the signal source is divided into a sine wave signal source and a pulse calibration source. The matching resistor R0 is connected in series with the sine wave signal source and the first metal test rod so as to combine and form a sine signal loop. The injection capacitor C0 is connected in series with the pulse calibration source and the second metal test rod so as to combine and form a pulse signal loop. The apparatus and the method are easy to realize, debugging is simple and rapid, and a test process is convenient and rapid. In the invention, the built-in signal source and an external signal source can be freely selected to carry out signal input. The apparatus and the method are suitable for routine maintenance, testing, verification and other occasions of the high-frequency partial discharge detector in an electric power detection industry.

Accurate phase calibration of PMUs and PMU calibrators

Abstract: A measurement setup is developed for accurate phase calibration of phasor measurement units (PMUs) and PMU calibrators. The measurement method is based on generating a reference signal with known phase with respect to a 1 pulse-per-second time reference using a stepped sine wave signal.

Determination and compensation of series resistances during whole-cell patch-clamp recordings using an active bridge circuit and the phase-sensitive technique

Abstract: We present a technique which combines two methods in order to measure the series resistance (R S) during whole-cell patch-clamp recordings from excitable and non-excitable cells. R S is determined in the amplifier's current-clamp mode by means of an active bridge circuit. The correct neutralization of the electrode capacitance and the adjustment of the bridge circuit is achieved by the so-called phase-sensitive method: Short sine wave currents with frequencies between 3 and 7 kHz are injected into the cells. Complete capacitance neutralization is indicated by the disappearance of the phase lag between current and voltage, and correct bridge balance is indicated by a minimized voltage response to the sine wave current. The R S value determined in the current-clamp mode then provides the basis for R S compensation in the voltage-clamp recording mode. The accuracy of the procedure has been confirmed on single-compartment cell models where the error amounted to 2-3 %. Similar errors were observed during dual patch clamp recordings from single neocortical layer 5 pyramidal cells where one electrode was connected to the bridge amplifier and the other one to a time-sharing, single-electrode current- and voltage-clamp amplifier with negligible R S. The technique presented here allows R S compensation for up to 80-90 %, even in cells with low input resistances (e.g., astrocytes). In addition, the present study underlines the importance of correct R S compensation by showing that significant series resistances directly affect the determination of membrane conductances as well as the kinetic properties of spontaneous synaptic currents with small amplitudes.

Determination of nanosecond pulse parameters on transfer function measurement for power transformer winding deformation

Abstract: Transfer function method is now a widely acceptable tool to diagnose transformer winding deformations. A sweep frequency sine wave generator is often used to excite the different modes of resonance and anti-resonances. However, it is time consuming. Nanosecond square wave pulse signal offers an alternative that can serve the same objective. However, as so far, there is no certain criterion for selecting pulse parameters. This paper provides a comprehensive method for the determination of nanosecond square wave pulse parameters for transfer function evaluation of power transformer for winding deformation studies.

Detection device and method for communication cable shielding layer state monitoring

Abstract: The invention discloses a detection device for communication cable shielding layer state monitoring, which comprises a sine wave sweep frequency signal generation module, a variable attenuator module, an impedance matching module and a reflection signal receiving module, wherein the sine wave sweep frequency signal generation module is configured to generate adjustable-frequency sine wave sweep frequency signals through a DDS technology as transmission signals; the variable attenuator module is configured to adjust the transmission power of the sine wave sweep frequency signal generation module according to actual condition demands; the impedance matching module is configured to carry out impedance matching on load of the communication cable itself to enable internal impedance of a signal source and input impedance of a transmission line starting end to achieve a matching state; and the reflection signal receiving module is configured to receive and reflect a response voltage signal difference and measure the amplitude ratio and the phase difference of response voltage signals The specific position of a fault point can be detected, the positioning is more accurate, the measured fault point distance is farther, and safe and reliable operation of the communication cable can be ensured

Modeling and Simulation of Non-Linear and Hysteresis Behavior of Magneto-Rheological Dampers in the Example of Quarter-Car Model

Abstract: This paper presents reviews of mathematical formulations and numerical simulation models of non-linear and dynamic hysteresis behaviors of magneto-rheological liquid dampers, viz. Bingham, Dahl, LuGre and Bouc-Wen models, developed in MATLAB®/Simulink® in the example of quarter-car model with the Golden Car parameters. It demonstrates numerical simulations of the magneto-rheological liquid damper models with different sets of parameters and discusses simulation results and performances of these four models for different road profile excitation signals, such as Heaviside step function, sine wave, random noise and white Gaussian noise.