• Title/Summary/Keyword: Harmonics suppression

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Novel Method for Circulating Current Suppression in MMCs Based on Multiple Quasi-PR Controller

  • Qiu, Jian;Hang, Lijun;Liu, Dongliang;Geng, Shengbao;Ma, Xiaonan;Li, Zhen
    • Journal of Power Electronics
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    • v.18 no.6
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    • pp.1659-1669
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    • 2018
  • An improved circulating current suppression control method is proposed in this paper. In the proposed controller, an outer loop of the average capacitor voltage control model is used to balance the sub-module capacitor voltage. Meanwhile, an individual voltage balance controller and an arm voltage balance controller are also used. The DC and harmonic components of the circulating current are separated using a low pass filter. Therefore, a multiple quasi-proportional-resonant (multi-quasi-PR) controller is introduced in the inner loop to eliminate the circulating harmonic current, which mainly contains second-order harmonic but also contains other high-order harmonics. In addition, the parameters of the multi-quasi-PR controller are designed in the discrete domain and an analysis of the stability characteristic is given in this paper. In addition, a simulation model of a three-phase MMC system is built in order to confirm the correctness and superiority of the proposed controller. Finally, experiment results are presented and compared. These results illustrate that the improved control method has good performance in suppressing circulating harmonic current and in balancing the capacitor voltage.

A Low-pass Filter with Wide-stop Band Using Radial-shaped Open Stub (광대역의 저지대역을 갖는 부채꼴 형태의 개방형 스터브를 이용한 저역통과 여파기)

  • Yoon, Ki-cheol;Kim, Seong-cheol
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.7
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    • pp.1237-1242
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    • 2016
  • In this paper, the low pass filter with harmonics suppression and rejection using parallel coupled-line and radial type open stub is presented. And the resultant characteristic of the proposed low pass filter is that the harmonics are suppressed and rejected in wide bandwidth due to the parallel coupled-line structure. The open stub of a low pass filter is constructed in radial type which can be used to adjust the size of filter. The size of the proposed low pass filter is $6.98{\times}7.60mm2$ and the cut off frequency is 2.45 GHz. And the filter is economical in unit cost and can be constructed easily and has the merit of mass product because the filter is composed of distributed element. Also, the widely rejected harmonics is 128 % in the bandwidth and the insertion and return losses of the low pass filter are 1.07 dB and 19.5 dB, respectively.

A Design of Size Reduced Ring-Hybrid using Coupled Lines of Hairpin Type (헤어핀 형태의 결합 선로를 이용한 소형화된 링 하이브리드의 설계)

  • Lee, Hong-Seop;Hwang, Hee-Yong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.5 s.120
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    • pp.547-552
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    • 2007
  • In this paper, the coupled microstrip lines of hairpin type are applied to design a compact microstrip ring hybrid. When the gap decreases, three attenuation poles are created by coupling between the lines. The proposed structure can achieve a significant reduction of size and suppression of the harmonics. And it has the same frequency responses of conventional ring hybrid at 2.55 GHz. The harmonics are suppressed to below -20 dB up to 12 GHz, including the third harmonic. The ring part size of the proposed ring hybrid is reduced to one forth of the conventional ring hybrid. The measured frequency responses agree well with simulated ones.

A Design of 90° Hybrid Coupler with Low Pass Filter Attenuation (저역통과 여파기 감쇠를 갖는 90° 하이브리드 특성에 관한 연구)

  • Lee, Su-Yeol;Kang, Jung-Hoon;Park, Kyu-Ho;Ahn, Dal
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.2
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    • pp.178-182
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    • 2004
  • In this paper, a 90$^{\circ}$ hybrid coupler with both power division and harmonic rejection characteristics is presented by applying a LPF characteristic to a conventional 90$^{\circ}$ hybrid. Since a conventional 90$^{\circ}$ hybrid coupler operates as a power divider/combiner using phase difference, it does not suppress higher order harmonics when it is incorporated with nonlinear amplifier. This requires an additional filter to take into account of the harmonics. The proposed 90$^{\circ}$hybrid coupler power provides the division capability and proper phase difference, as well as harmonic suppression characteristic by integrating LPF characteristic.

Design of a Compact Bandstop Filter-combined UHF-band CRLH Bandpass Filter to Suppress the Spurious in L-band (L대역 불요파 저감을 위한, UHF대역 CRLH 대역통과 여파기와 소형 대역저지 여파기의 결합 설계)

  • Eom, Da-Jeong;Kahng, Sung-Tek;Mok, Se-Gyoon;Song, Choong-Ho;Woo, Chun-Sik;Park, Do-Hyun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.1
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    • pp.104-109
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    • 2012
  • In this paper, we propose a way to improve the quality of L-band wireless communication from unfriendly influential factors lying in the neighboring RF bands. The UHF-band system has resonator components and they generate harmonics as the spurious in the L-band. Therefore, a metamaterial CRLH bandpass filter is designed for the purpose of system miniaturization and smaller insertion loss, and its spurious phenomenon is observed in the frequency domain. And its harmonics in the L-band are suppressed by a compact bandstop filter whose equivalent circuit is newly developed. The design methodology is validated by the equivalent circuit to be compared with commercial full-wave EM software simulations, where the spurious is dropped by 20dB. Also, the advantage of the proposed design is presented by the comparison where our filter is much smaller than the conventional parallel edge coupled filter by over 50%, with excellent harmonic suppression.

Unbalance Control Strategy of Boost Type Three-Phase to Single-Phase Matrix Converters Based on Lyapunov Function

  • Xu, Yu-xiang;Ge, Hong-juan;Guo, Hai
    • Journal of Power Electronics
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    • v.19 no.1
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    • pp.89-98
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    • 2019
  • This paper analyzes the input side performance of a conventional three-phase to single-phase matrix converter (3-1MC). It also presents the input-side waveform quality under this topology. The suppression of low-frequency input current harmonics is studied using the 3-1MC plus capacitance compensation unit. The constraint between the modulation function of the output and compensation sides is analyzed, and the relations among the voltage utilization ratio and the output compensation capacitance, filter capacitors and other system parameters are deduced. For a 3-1MC without large-capacity energy storage, the system performance is susceptible to input voltage imbalance. This paper decouples the inner current of the 3-1MC using a Lyapunov function in the input positive and negative sequence bi-coordinate axes. Meanwhile, the outer loop adopts a voltage-weighted synthesis of the output and compensation sides as a cascade of control objects. Experiments show that this strategy suppresses the low-frequency input current harmonics caused by input voltage imbalance, and ensures that the system maintains good static and dynamic performances under input-unbalanced conditions. At the same time, the parameter selection and debugging methods are simple.

Harmonic Suppression Compact Microstrip Patch Antenna for IoT Sensor (고조파 억제를 위한 IoT 센서용 소형 마이크로스트립 패치 안테나)

  • Lee, Hyun-Seung;Lim, Jeong-Taek;Jung, Bang-Chul;Kim, Choul-Young
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.18 no.6
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    • pp.85-89
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    • 2017
  • This paper proposes an antenna incorporating a bandstop filter to miniaturize the rectenna used for wireless power transmission with the emerging interest these days. To suppress the harmonics that can be re-radiated, this paper proposes a microstrip patch antenna that can suppress the harmonics while maintaining the size of the antenna by inserting a U-slot, which acts as a bandstop filter, on the ground plane of the antenna. As a result, S11 of the second harmonic(4.6GHz) was reduced from -5.61dB to -0.338dB and the efficiency was suppressed significantly from 29.76% to 1.5%. In addition, the maximum gain was reduced to -12dBi from 2.89dBi. On the other hand, at the fundamental frequency (2.45GHz), the S11 value was reduced from -18 dB to -15 dB, and the efficiency was reduced slightly from 68.2% to 60%. In the case of applying a microstrip antenna combined with the proposed bandstop filter to a rectenna, it is believed that the harmonics that degrade the performance of the rectenna can be removed effectively while reducing the large area occupied by harmonic suppression.

Design of a 5.8 GHz Broad Band-Pass Filter with Second of Harmonics Suppression Using the Open Stubs (2차 고조파가 억제된 5.8 GHz 광대역 개방형 스터브 대역 통과 여파기 설계)

  • Choi, Young-Gu;Kim, Bok-Ki
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.10
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    • pp.1107-1116
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    • 2007
  • In this paper, a broadband open stubs band pass filters which can suppress the second harmonics using Z-transform technique, is designed, fabricated and characterized. The proposed broadband filters integrate the band stop filter with the FSCS structure and ${\lambda}_g/4$ open stub in order to suppress the second harmonics. Due to insertion of BSF at input and output terminal, the size of the filter was increased in the conventional filter, however, in the proposed structure, the position of inverter that connects the stubs can be integrated between those stubs, thereby decreasing the size. So, it can be fabricated in the size of $18.7{\times}16.9mm^2$ which is smaller size than conventional one. The measured results of the proposed filters have center frequency of a 5.8 GHz with bandwidth of 95 %, insertion loss of 0.6 dB, return loss of 14 dB. The simulation results are consistent with measurement results. The filter is designed far X-band satellite communication and ITS applications.

Study of Multi Function RF Module Using Amplifier and Multiplier (증폭기 및 체배기를 이용한 다기능 RF 모듈에 관한 연구)

  • Kim, Tae-Hoon;Joo, Jae-Hyun;Koo, Kyung-Heon
    • Journal of Advanced Navigation Technology
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    • v.14 no.3
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    • pp.391-396
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    • 2010
  • This paper presents some important research result comparisons for multi function RF modules which use amplifier or frequency multiplier. By using multiplier, multi function module can be realized amply in comparison to multi band module which has separate block for each frequency band. Some com paring analysis among the switching method between separate amplifier and multiplier, the structure using frequency selective reflector, and the module using the defected ground structure. The multi function module which operates as amplifier or multiplier with input frequency is developed and input frequency suppression and output harmonics suppression can be improve d by using defected ground structure.

A Harmonic Suppressed Design of Size Reduced Ring-Hybrid Using Folded Line Structure (소형화 및 고조파 특성이 개선된 접힌 구조의 링-하이브리드의 설계)

  • Lee Hong-Seop;Lee Chul-Heui;Hwang Hee-Yong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.9 s.112
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    • pp.845-851
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    • 2006
  • Folded lines are applied to design a compact microstrip ring hybrid. Using the proposed structure we achieve both significant size reduction and good harmonic suppression with the same results of conventional ring hybrid at 2.41 GHz. Including the third harmonic frequency, up to 11 GHz band harmonics are suppressed to -20 dB. The size of the proposed ring-hybrid is reduced to one forth of the conventional ring hybrid. The measured frequency responses agree well with simulated ones.