• 한국통신학회논문지
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• 제13권6호
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• pp.529-534
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• 1988

본 논문에서는 PWM인버터의 임의의 고조파를 제거할 때 프리에급수를 이용하여 비선형 연립방정식을 선형 연립방정식으로 바꾸던 것을 왈쉬급수를 이용하여 임의의 고조파를 제거하는 새로운 방법을 제시하였다. PWM인버터의 고조파제거에서 왈쉬급수를 이용하여 파형을 분석하고, 왈쉬급수와 프리에급수를 이용하여 비교 분석하였으며, 또한 단상 PWM인버터의 출력파혀을 왈쉬급수를 이용하여 시뮬레이션하고 실험을 통하여 임의의 고조파가 제거됨을 확인한다.

• Journal of Power Electronics
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• 제17권4호
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• pp.933-941
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• 2017

In this paper an improved low frequency selective harmonic elimination-PWM (SHE-PWM) technique for Cascaded H-bridge (CHB) converters is proposed. The proposed method is able to eliminate low order harmonics from the output voltage of the converter for a wide range of modulation indices. To solve SHE-PWM equations, especially for low modulation indices, a modified method is used which employs either the positive or negative voltage polarities of H-bridge cells to increase the freedom degrees of each cell. Freedom degrees of the switching angles are also used to increase the range of available solutions for non-linear SHE equations. The proposed SHE methods can successfully eliminate up to $25^{th}$ harmonic from a 7-level output voltage by using just nine switching transitions or a 150 Hz switching frequency. To confirm the validity of the proposed method, simulation and experimental results have been presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 연구회 합동 학술발표회 논문집
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• pp.64-67
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• 1998

This paper proposes the hybrid PWM scheme that can obtain less harmonic characteristics in GTO inverters. By employing the variable of the dc-link voltage Vdc, the hybrid PWM pattern can ideally compensate the dc input fluctuation together with selected harmonics elimination. The transient behavior, which the magnetic flux and torque are altered and the large current flows instantly, may be produced when the mode change. To reduce such an undesirable transient behavior, it is also presented the technique for the gear changing of inverter operated with the hybrid PWM. The results are verified by simulations and experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1296-1297
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• 2015

마이크로 웨이브를 사용하는 기기들은 대량생산 공정에 있어서 식품 가공용 건조기기로 사용되고 있다. 3kW 마그네트론을 구동하기 위해서는 필라멘트를 가열하고 고압의 DC전원을 발생할 수 있는 회로가 필요하게 된다. 반도체 소자를 이용한 전력변환 장치로 DC로 운전이 되면 AC계통으로 혼입되는 고조파가 발생된다. 본 논문에서 AC계통으로 유입되는 특정고조파 제거 방법을 제안한다. 고조파 검출회로를 기반으로 전류를 제어함으로써 기존 LC필터에서 제거되지 못한 고조파성분이 감쇠되는 성능을 보였다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 추계학술대회
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• pp.95-97
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• 2018

The power quality of Single Phase Grid-Connected Inverters (GCIs) has received much attention with the increasing number of Distributed Generation (DG) systems. However, the performance of single phase GCIs get degraded due to several factors such as the grid voltage harmonics, the dead time effect, and the turn ON/OFF of the switches, which causes the harmonics at the output of GCIs. Therefore, it is not easy to satisfy the harmonic standards such as IEEE 519 and P1547 without the help of harmonic compensator. To meet the harmonic standards a certain kind of harmonic controller needs to be added to the current control loop to effectively mitigate the low order harmonics. In this paper, the harmonic compensation is performed using a novel robust harmonic compensation method based on Digital Lock-in Amplifier (DLA). In the proposed technique, DLAs are used to extract the amplitude and phase information of the harmonics from the output current and compensate it by using a simple PI controller in the feedforward manner. In order to show the superior performance of the proposed harmonic compensation technique, it is compared with those of conventional harmonic compensation methods in terms of the effectiveness of harmonic elimination, complexity, and implementation. The validity of the proposed harmonic compensation techniques for the single phase GCIs is verified through the experimental results with a 5kW single phase GCI. Index Terms -Single Phase Grid Connected Inverter (SPGCI), Harmonic Compensation Method, Total Harmonic Distortion (THD) and Harmonic Standard.

• 전력전자학회논문지
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• 제13권3호
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• pp.237-245
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• 2008

최근 중대용량의 교류전동기 구동에 다단 H-브릿지 인버터의 적용이 늘어나고 있다. 이 인버터의 주된 장점 중의 하나는 입력전류에 고조파성분이 적다는 것으로 이는 2차측이 다중의 위상이동 권선으로 이루어진 변압기를 사용함으로써 이루어진다. 본 논문은 다단 H-브릿지 인버터에 적용되는 위상이동 변압기의 권선 설계의 기본 방안과 입력전류 고조파의 이론적인 해석을 제시하고 있다. 위상이동 변압기를 다룬 I부에 이어 II부에서는 입력 선전류의 고조파 특성을 해석함으로써 고조파 제거를 위한 등간격 위상차 설정방식의 이론적 근거를 규명하였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권12호
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• pp.671-678
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• 1999

In this study, it has been aimed that the accuracy of position control be increased by microstep drive to the 2 phase 8 pole HB type prototype of linear pulse motor of which winding are applied sine wave current and the vibration and noise in the lower speed region be decreased. The fixed off-time method which controls the exciting current bandwidth, was applied to the microstep current controller. When the LPM was driven 1/8 microstep its accuracy of position was 0.109[mm] (=tooth pitch 3.5[mm] ). Also, the elimination method of harmonics in the static thrust force is proposed. It was confirmed that the position error range of the prototype LPM was $\pm$0.2[mm].

• Journal of Power Electronics
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• 제10권2호
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• pp.155-164
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• 2010

This paper presents a voltage control algorithm for a hybrid multilevel inverter based on a staged-perception of the inverter voltage vector diagram. The algorithm is applied to control a three-stage eighteen-level hybrid inverter, which has been designed with a maximum number of symmetrical levels. The inverter has a two-level main stage built using a conventional six-switch inverter and medium- and low- voltage three-level stages constructed using cascaded H-bridge cells. The distinctive feature of the proposed algorithm is its ability to avoid the undesirable high switching frequency for high- and medium- voltage stages despite the fact that the inverter's dc sources voltages are selected to maximize the number of levels by state redundancy elimination. The high- and medium- voltage stages switching algorithms have been developed to assure fundamental switching frequency operation of the high voltage stage and not more than few times this frequency for the medium voltage stage. The low voltage stage is controlled using a SVPWM to achieve the reference voltage vector exactly and to set the order of the dominant harmonics. The inverter has been constructed and the control algorithm has been implemented. Test results show that the proposed algorithm achieves the desired features and all of the major hypotheses have been verified.

• Journal of Power Electronics
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• 제14권3호
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• pp.488-498
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• 2014

This paper presents an implementation of selective harmonic elimination (SHE) modulation for a single-phase 13-level transistor-clamped H-bridge (TCHB) based cascaded multilevel inverter. To determine the optimum switching angle of the SHE equations, the Newton-Raphson method is used in solving the transcendental equation describing the fundamental and harmonic components. The proposed SHE scheme used the relationship between the angles and a sinusoidal reference waveform based on voltage-angle equal criteria. The proposed SHE scheme is evaluated through simulation and experimental results. The digital modulator based-SHE scheme using a field-programmable gate array (FPGA) is described and has been implemented on an Altera DE2 board. The proposed SHE is efficient in eliminating the $3^{rd}$, $5^{th}$, $7^{th}$, $9^{th}$ and $11^{th}$ order harmonics, which validates the analytical results. From the results, it can be seen that the adopted 13-level inverter produces a higher quality with a better harmonic profile and sinusoidal shape of the stepped output waveform.

• 대한전자공학회논문지
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• 제27권10호
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• pp.124-129
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• 1990

PWM 인버터에서 임의로 선택한 5,7,11차 고조파를 제거할 때, 후리에 급수를 이용하여 비선형 연립방식을 선형 연립방정식으로 바꾸어 점호각을 분석하던 기존의 방법으로부터 새로운 방법을 구현하였다. 후리에 급수를 이용하여 기억소자에 점호각을 look-up 표로 기억시키거나, 또는 점호각 계산 프로그램을 반복 수행하여 점호시각에 트리거하던 기존의 방법으로는 실시간 제어가 곤란하였다. 본 논문에서는 제안된 왈쉬 급수를 이용하여 점호각을 계산하고 하드웨어로 구성하여 입력되는 클럭 주파수만 가변하면, 즉시로 가변된 주파수가 출력되므로 실시간 제어가 가능함을 밝혔다. 또한 Ordered orthogonal 함수를 이용하여 단상회로와 동일한 하드웨어 구성으로 3장 출력이 가능함을 실험을 통하여 확인하였다.