scholarly journals Novel Common-Mode Current Suppression Method in Transformerless PV Grid-Connected System

2018 ◽  
Vol 8 (11) ◽  
pp. 2072 ◽  
Author(s):  
Dongliang Liu ◽  
Haoqi Zhu ◽  
Ruiguang Zhao
Keyword(s):  
High Frequency ◽  
Equivalent Circuit Model ◽  
Common Mode ◽  
Cause Analysis ◽  
Resonant Problem ◽  
Grid Connection ◽  
Frequency Components ◽  
Suppression Method ◽  
The Stability ◽  
Pv Grid

The existence of high-frequency components in common-mode (CM) current would reduce the stability of a non-isolated PV grid-connected system. It has great impacts on the output power quality when the generated power from PV is low. The method of single CM inner loop in suppressing the high-frequency components has poor effect. Based on the CM equivalent circuit model and the cause analysis of the CM current, a novel dual CM inner loops method is proposed to restrain the high-frequency components in CM current. This method not only meets the grid connection demand of CM current, but also overcomes the high frequency resonant problem. Furthermore, the high-frequency components in CM current from the outer parasitic circuit are substantially reduced. Finally, the proposed method is verified by simulation and experimental results.

Suppression Approaches of Far-Field Radiated Emission Using Common-Mode Inductor

2021 ◽  
Vol 1 (2) ◽  
pp. 1-5
Author(s):  
Mengzi Li ◽  
◽  
Shishan Wang ◽  
Jian Guo
Keyword(s):  
High Frequency ◽  
Reference Value ◽  
Power Converter ◽  
Practical Significance ◽  
Far Field ◽  
Common Mode ◽  
Suppression Method ◽  
Switching Mode ◽  
Emc Design ◽  
Radiated Emission

The miniaturization and integration of Switching Mode Power Supply (SMPS) is increasing, making it more complicated to analyze and predict its far-field radiated emission, and, consequently, studying the suppression method of far-field radiated emission of SMPS is of practical significance and engineering value. In this paper, a high-frequency SMPS is selected as the research object, whose far-field radiated emission is measured under the condition of three typical suppression methods. The experimental results verified the effectiveness of common-mode inductor and are of reference value for EMC design of power converter. Keywords: SMPS; EMC; Far-field Radiated Emission;

scholarly journals Common-Mode Voltage Analysis and Reduction for the Quasi-Z-Source Inverter with a Split Inductor

2020 ◽  
Vol 10 (23) ◽  
pp. 8713
Author(s):  
Wenjie Liu ◽  
Yongheng Yang ◽  
Tamas Kerekes ◽  
Elizaveta Liivik ◽  
Dmitri Vinnikov ◽  
...  
Keyword(s):  
High Frequency ◽  
Experimental Tests ◽  
Voltage Source ◽  
Leakage Currents ◽  
Common Mode ◽  
Pv Systems ◽  
Common Mode Voltage ◽  
Reduction Strategies ◽  
Frequency Components ◽  
Converter Topology

In transformerless grid-connected photovoltaic (PV) systems, leakage currents should be properly addressed. The voltage fluctuations between the neutral point of the grid and the PV array, i.e., common-mode voltage (CMV), will affect the value of the leakage currents. Therefore, the leakage currents can be attenuated through proper control of the CMV. The CMV depends on the converter topology and the modulation strategy. For the quasi-Z-source inverter (qZSI), the amplitude of the high-frequency components in the CMV increases due to the extra shoot-through (ST) state. The CMV reduction strategies for the conventional voltage source inverter (VSI) should be modified when applied to the qZSI. In this paper, an input-split-inductor qZSI is introduced to reduce the CMV, in which all the CMV reduction strategies for the VSI can be used directly with appropriate ST state insertion. Moreover, the proposed method can be extended to impedance source converters with a similar structure. Simulations and experimental tests demonstrate the effectiveness of the proposed strategy for the qZSI in terms of CMV reduction.

scholarly journals Design of High Speed and Precision and Low-Power LVDS Driver for CMOS Image Sensor

2020 ◽  
Vol 38 (2) ◽  
pp. 442-450
Author(s):  
Chuangze Li ◽  
Benguang Han ◽  
Jie He ◽  
Longsheng Wu
Keyword(s):  
Low Power ◽  
High Frequency ◽  
High Speed ◽  
Cmos Image Sensor ◽  
Image Sensor ◽  
Compensation Method ◽  
Common Mode ◽  
General Design ◽  
Frequency Components ◽  
The Common

Aiming at the requirement of high speed and precision, low-power and large-capacity load of serial data interface for aerospace super large array(15k×15k) CMOS image sensor, a design scheme low voltage differential signal (LVDS) driver by combining the split-length method with the pre-emphasis technique is proposed. Firstly, comparing with the general design schemes, the present scheme uses the split-length compensation method to increase effectively the unity-gain bandwidth while keeping the op-amp gain constant. Secondly, the pre-emphasis technique is used to compensate the LVDS driver for high-frequency components to improve the driving capability of the capacitive load and high speed signal integrity (SI). The simulation results show that the accuracy of the common-mode feedback voltage is improved by using the split-length compensation method, and also the common-mode voltage changes below 15 mV. The pre-emphasis technique is used to enhance the amplitude of the high-frequency components lost during the high-speed transmission. The quality of the signal eye diagram during high-speed transmission reduces the bit error rate, and both the transmission rate and the driving load capacity are two times more than the general design (1.2 Gb/s@12 pF), and the quiescent current consumption is only 4.6 mA@12 pF. The present LVDS driver design is implemented in a typical CMOS process of 0.18 μm.

scholarly journals Harmonic analysis of the stability of reverse routing in channels

2007 ◽  
Vol 11 (1) ◽  
pp. 559-568 ◽  
Author(s):  
M. Bruen ◽  
J. C. I. Dooge
Keyword(s):  
Harmonic Analysis ◽  
High Frequency ◽  
Stable Process ◽  
Linear Solution ◽  
Wave Patterns ◽  
Upstream Direction ◽  
Frequency Components ◽  
The Stability ◽  
Channel Lengths ◽  
Flood Flow

Abstract. Normal downstream routing of a flood flow is a highly stable process for Froude numbers less than 1 and hence the results are reliable. In contrast, reverse routing in an upstream direction, which may be required for flow control, is potentially unstable. This paper reports the results of a study of the practical limits on channel lengths for reverse routing. Harmonic analysis is applied to the full non-linear solution of the St. Venant equations for three different wave patterns and two different wave periods, for a particular channel with a Froude number of 0.5. Reverse routing can be done for prismatic channels longer than 100 km. For long periods (>10 hours) the shape of the upstream hydrograph is recovered well. However, when the wave period is short (<1 hour), the high frequency components of the upstream hydrograph and, thus, its shape, are not recovered. These limits are influenced by the channel morphology and shape of the wave. Further work is needed to determine how these factors interact.

A New High Frequency Transformer PV Grid-Connected Inverter

2013 ◽  
Vol 325-326 ◽  
pp. 515-518
Author(s):  
Ye Geng ◽  
Li Gong ◽  
Y.B. Chen
Keyword(s):  
High Frequency ◽  
Topology Control ◽  
Single Phase ◽  
Simulation Models ◽  
Grid Connection ◽  
High Frequency Transformer ◽  
Grid Connected Inverter ◽  
Pv Grid ◽  
Inverter Topology

This paper focuses a new high frequency transformer inverter technology for connecting photovoltaic (PV) panels to a single-phase grid. The information provided includes the inverter topology, control diagrams, and simulation models. The results show that the performance of the proposed inverter meets the grid connection requirements.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

A Simple Technique for Estimating the Winding Stray Capacitance of High-Frequency Three-Phase Common-Mode Inductors

2019 ◽  
Vol 139 (3) ◽  
pp. 339-347 ◽  
Author(s):  
Shotaro Takahashi ◽  
Satoshi Ogasawara ◽  
Masatsugu Takemoto ◽  
Koji Orikawa ◽  
Michio Tamate
Keyword(s):  
High Frequency ◽  
Simple Technique ◽  
Stray Capacitance ◽  
Common Mode ◽  
Three Phase

A Novel Adaptive PET/CT Image Fusion Algorithm

2019 ◽  
Vol 14 (7) ◽  
pp. 658-666
Author(s):  
Kai-jian Xia ◽  
Jian-qiang Wang ◽  
Jian Cai
Keyword(s):  
Lung Cancer ◽  
Image Fusion ◽  
High Frequency ◽  
Malignant Tumors ◽  
Low Frequency ◽  
Combination Method ◽  
Ct Image ◽  
Fusion Algorithm ◽  
Pet Ct ◽  
Frequency Components

Background: Lung cancer is one of the common malignant tumors. The successful diagnosis of lung cancer depends on the accuracy of the image obtained from medical imaging modalities. Objective: The fusion of CT and PET is combining the complimentary and redundant information both images and can increase the ease of perception. Since the existing fusion method sare not perfect enough, and the fusion effect remains to be improved, the paper proposes a novel method called adaptive PET/CT fusion for lung cancer in Piella framework. Methods: This algorithm firstly adopted the DTCWT to decompose the PET and CT images into different components, respectively. In accordance with the characteristics of low-frequency and high-frequency components and the features of PET and CT image, 5 membership functions are used as a combination method so as to determine the fusion weight for low-frequency components. In order to fuse different high-frequency components, we select the energy difference of decomposition coefficients as the match measure, and the local energy as the activity measure; in addition, the decision factor is also determined for the high-frequency components. Results: The proposed method is compared with some of the pixel-level spatial domain image fusion algorithms. The experimental results show that our proposed algorithm is feasible and effective. Conclusion: Our proposed algorithm can better retain and protrude the lesions edge information and the texture information of lesions in the image fusion.

Despeckling of Sar Images Using Shrinkage of Two-Dimensional Discrete Orthonormal S-Transform

2020 ◽  
pp. 2150023
Author(s):  
Priya R. Kamath ◽  
Kedarnath Senapati ◽  
P. Jidesh
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Relevant Information ◽  
Detection Algorithm ◽  
Two Dimensional ◽  
Sar Images ◽  
S Transform ◽  
Processing Step ◽  
Frequency Components ◽  
Shock Filter

Speckles are inherent to SAR. They hide and undermine several relevant information contained in the SAR images. In this paper, a despeckling algorithm using the shrinkage of two-dimensional discrete orthonormal S-transform (2D-DOST) coefficients in the transform domain along with shock filter is proposed. Also, an attempt has been made as a post-processing step to preserve the edges and other details while removing the speckle. The proposed strategy involves decomposing the SAR image into low and high-frequency components and processing them separately. A shock filter is used to smooth out the small variations in low-frequency components, and the high-frequency components are treated with a shrinkage of 2D-DOST coefficients. The edges, for enhancement, are detected using a ratio-based edge detection algorithm. The proposed method is tested, verified, and compared with some well-known models on C-band and X-band SAR images. A detailed experimental analysis is illustrated.

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