scholarly journals Review and Simulation of Fixed and Adaptive Hysteresis Current Control Considering Switching Losses and High-Frequency Harmonics

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Hani Vahedi ◽  
Abdolreza Sheikholeslami ◽  
Mohammad Tavakoli Bina ◽  
Mahmood Vahedi
Keyword(s):  
Fourier Transform ◽  
High Frequency ◽  
Current Control ◽  
Switching Frequency ◽  
Hysteresis Current Control ◽  
Switching Losses ◽  
Frequency Components ◽  
Source Current ◽  
Harmonic Components ◽  
The Fourier Transform

Hysteresis Current Control (HCC) is widely used due to its simplicity in implementation, fast and accurate response. However, the main issue is its variable switching frequency which leads to extraswitching losses and injecting high-frequency harmonics into the system current. To solve this problem, adaptive hysteresis current control (AHCC) has been introduced which produces hysteresis bandwidth which instantaneously results in smoother and constant switching frequency. In this paper the instantaneous power theory is used to extract the harmonic components of system current. Then fixed-band hysteresis current control is explained. Because of fixed-band variable frequency disadvantages, the adaptive hysteresis current control is explained that leads to fixing the switching frequency and reducing the high-frequency components in source current waveform. Due to these advantages of AHCC, the switching frequency and switching losses will be diminished appropriately. Some simulations are done in MATLAB/Simulink. The Fourier Transform and THD results of source and load currents and the instantaneous switching frequency diagram are discussed to prove the efficiency of this method. The Fourier Transform and THD results of source and load currents are discussed to prove the validity of this method.

A New Hysteresis Current Control Method for Active Power Filter with Lower Switching Losses

2014 ◽  
Vol 1030-1032 ◽  
pp. 1423-1431
Author(s):  
Jiang Zeng ◽  
Li Peng Huang
Keyword(s):  
Control Method ◽  
Active Power Filter ◽  
Active Power ◽  
Current Control ◽  
Band Width ◽  
Switching Frequency ◽  
Hysteresis Current Control ◽  
Power Filter ◽  
Switching Losses ◽  
Control Precision

This paper presents a new hysteresis current control method for APF(active power filter) that can reduce switching losses effectively by means of adjusting the hysteresis band width according to the current size. On one hand, this method adjust the overall hysteresis band width according to the size of absolute norm of three-phase current that optimize the overall switching frequency, reduce the total switching losses effectively. On the other hand, it adjust hysteresis band width of each phase by comparing the output reference current to reduce the switching times which switching losses is larger, while increasing the switching frequency which switching losses is smaller, so as to maintain overall control precision. Computer simulation is conducted on an electromagnetic transient program. The results show that the new method can effectively reduce the switching losses under the same control accuracy and total switching frequency.

A Hysteretic Current Controller for Active Power Filter (APF) with Constant Frequency

2012 ◽  
Vol 460 ◽  
pp. 308-312
Author(s):  
Qing Shou Song
Keyword(s):  
Control Method ◽  
Current Control ◽  
Switching Frequency ◽  
Matlab Simulation ◽  
Constant Frequency ◽  
Hysteresis Current Control ◽  
Power Filter ◽  
Switching Losses ◽  
Current Controller ◽  
Frequency State

In accordance with the advantage of conventional hysteresis current control method, this paper advances a novel control method for APF. In conventional hysteresis current control, the hysteresis band (HB) is fixed and actual compensating current is limited in a fixed HB. Firstly, the connection between HB and switching frequency must be found correctly. Then, the variable hysteresis band current controller is designed according to the connection. Finally, the Matlab simulation results show that the switching frequency of VSI is held nearly constant and the proposed controller can track reference current well[1]. The problems of increasing switching losses and audible noise which happened in high-frequency state can be resolved in conventional hysteresis current control.

Analysis of Fast-Scale Bifurcation in Peak Current Controlled Buck-Boost Inverter Based on Unified Averaged Model

2016 ◽  
Vol 26 (05) ◽  
pp. 1650074 ◽  
Author(s):  
Hao Zhang ◽  
Shuai Dong ◽  
Weimin Guan ◽  
Ye Liu
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Period Doubling ◽  
Current Control ◽  
High Frequency Oscillation ◽  
Switching Frequency ◽  
Unified Framework ◽  
Frequency Oscillation ◽  
Peak Current ◽  
Averaged Model

In this paper, a unified averaged modeling method is proposed to investigate the fast-scale period-doubling bifurcation of a full-bridge integrated buck-boost inverter with peak current control. In order to increase the resolution of the conventional classic averaged model to half the switching frequency, sample-and-hold effect of inductor current is absorbed into the averaged model, i.e. the proposed unified averaged model can capture the high-frequency dynamical characteristics of the buck-boost inverter, which is both an extension and a modification of conventional averaged model. Based on the unified mode, fast-scale bifurcation is identified, and the corresponding bifurcation point is predicted with the help of the locus movement of all the poles, and their underlying mechanisms are revealed. Detailed analysis shows that the occurrence of high-frequency oscillation means fast-scale bifurcation, while the occurrence of low-frequency oscillation leads to slow-scale bifurcation. Finally, it is demonstrated that the unified averaged model can provide not only a general method to investigate both the slow- and fast-scale bifurcations in a unified framework but also a quite straightforward design-oriented method which can be directly applicable.

Coherence based on spectral variance analysis

Geophysics ◽  
2018 ◽  
Vol 83 (3) ◽  
pp. O55-O66 ◽  
Author(s):  
Yanting Duan ◽  
Chaodong Wu ◽  
Xiaodong Zheng ◽  
Yucheng Huang ◽  
Jian Ma
Keyword(s):  
Fourier Transform ◽  
Seismic Data ◽  
High Frequency ◽  
Seismic Interpretation ◽  
Variance Analysis ◽  
Frequency Spectra ◽  
Amplitude Spectra ◽  
Frequency Components ◽  
Spectral Variance ◽  
Coherence Estimation

The eigenstructure-based coherence attribute is a type of efficient and mature tool for mapping geologic edges such as faults and/or channels in the 3D seismic interpretation. However, the eigenstructure-based coherence algorithm is sensitive to low signal-to-noise ratio seismic data, and the coherence results are affected by the dipping structures. Due to the large energy gap between the low- and high-frequency components, the low-frequency components play the principal role in coherence estimation. In contrast, the spectral variance balances the difference between the low- and high-frequency components at a fixed depth. The coherence estimation based on amplitude spectra avoids the effect of the time delays resulting from the dipping structures. Combining the spectral variance with the amplitude spectra avoids the effect of dipping structures and enhances the antinoise performance of the high-frequency components. First, we apply the short-time Fourier transform to obtain the time-frequency spectra of seismic data. Next, we compute the variance values of amplitude spectra. Then, we apply the fast Fourier transform to obtain the amplitude spectra of spectral variance. Finally, we calculate the eigenstructure coherence by using the amplitude spectra of spectral variance as the input. We apply the method to the theoretical models and practical seismic data. In the Marmousi velocity model, the coherence estimation using the amplitude spectra of the spectral variance as input shows more subtle discontinuities, especially in deeper layers. The results from field-data examples demonstrate that the proposed method is helpful for mapping faults and for improving the narrow channel edges’ resolution of interest. Therefore, the coherence algorithm based on the spectral variance analysis may be conducive to the seismic interpretation.

The Simulation Research of Two State Markov Chain in the Double Random SVPWM of the Variable Frequency Control System

2014 ◽  
Vol 971-973 ◽  
pp. 1828-1833
Author(s):  
Bo Zheng ◽  
Hong Zheng
Keyword(s):  
Markov Chain ◽  
Control System ◽  
High Frequency ◽  
Frequency Control ◽  
Switching Frequency ◽  
Variable Frequency ◽  
Output Current ◽  
Frequency Control System ◽  
Variable Frequency Control ◽  
Harmonic Components

At present the Space Vector Pulse Width Modulation (SVPWM) technique has been widely used in the variable frequency control system,but the technique will make the system produce higher harmonic components at the switching frequency integer multiple times,thus the harmonic produce the high frequency noise.In the face of this problem, this paper adopts double random SVPWM technique which is added two state Markov chain to effectively reduce the high frequency noise.The technique makes the harmonic components amplitude value of the output current reduced effectively in the inverter of the variable frequency control system,so that the more output current is more relatively evenly distributed in the wide frequency range,so as to minimize the electromagnetic noise.

Research on the High Frequency Realization of High-Power Inverter

2011 ◽  
Vol 383-390 ◽  
pp. 1077-1083
Author(s):  
Run Hua Liu ◽  
Gang Wang
Keyword(s):  
High Power ◽  
High Frequency ◽  
Output Voltage ◽  
Harmonic Distortion ◽  
Soft Switching ◽  
Multilevel Inverter ◽  
Switching Frequency ◽  
Switching Losses ◽  
Simulation And Experiment

The paper presents the inverter method which based on cascade multilevel inverter and MOSFET-assisted soft-switching of IGBT and modulation strategy against the double requirement of high-power inverter and high frequency. The method can effectively improve the output voltage, reduce harmonic distortion and switching losses, improve the switching frequency and meet the double requirement of the high-power inverter and high frequency. The method proved to be feasible by simulation and experiment.

Comparison of adaptive and fixed-band hysteresis current control considering high frequency harmonics

2011 ◽  
Author(s):  
Hani Vahedi ◽  
Yasser Rahmati Kukandeh ◽  
Mahsa Ghapandar Kashani ◽  
Aliakbar Dankoob ◽  
Abdolreza Sheikholeslami
Keyword(s):  
High Frequency ◽  
Current Control ◽  
Hysteresis Current Control
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