• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제52권11호
• /
• pp.563-571
• /
• 2003

In this paper, the control algorithm and control method for a combined system of shunt passive filter and series active filter in 3-phase 4-wire system are discussed. Moreover, the three-phase four-wire system is widely employed in distributing electric energy to several office building and manufacturing plants. In such systems, the third harmonic and its 3th harmonics are termed as triple and zero sequence components that do not cancel each other in the system neutral. Consequently, the triple harmonics add together creating a primary source of excessive neutral current. Regarding this concern, this paper presents a new control algorithm for a series hybrid active system, whereas the control approach it adopts may directly influence its compensation characteristics. Hence, the advantage of this control algorithm is direct extraction of compensation voltage reference and the required rating of the series active filter is much smaller than that of a conventional shunt active filter. Some experiments were executed and experimental results from a prototype active power filter confirm the suitability of the proposed approach.

• Journal of Electrical Engineering and Technology
• /
• 제8권2호
• /
• pp.304-315
• /
• 2013

In this paper, analysis of cascaded H-bridge multilevel inverter in DTC-SVM (Direct Torque Control-Space Vector Modulation) based induction motor drive for FCEV (Fuel Cell Electric Vehicle) is presented. Cascaded H-bridge multilevel inverter uses multiple series units of H-bridge power cells to achieve medium-voltage operation and low harmonic distortion. In FCEV, a fuel cell stack is used as the major source of electric power moreover the battery and/or ultra-capacitor is used to assist the fuel cell. These sources are suitable for utilizing in cascaded H-bridge multilevel inverter. The drive control strategy is based on DTC-SVM technique. In this scheme, first, stator voltage vector is calculated and then realized by SVM method. Contribution of multilevel inverter to the DTC-SVM scheme is led to achieve high performance motor drive. Simulations are carried out in Matlab-Simulink. Five-level and nine-level inverters are applied in 3hp FCEV induction motor drive for analysis the multilevel inverter. Each H-bridge is implemented using one fuel cell and battery. Good dynamic control and low ripple in the torque and the flux as well as distortion decrease in voltage and current profiles, demonstrate the great performance of multilevel inverter in DTC-SVM induction motor drive for vehicle application.

• 반도체디스플레이기술학회지
• /
• 제7권2호
• /
• pp.23-27
• /
• 2008

Recently, regulation for THD (Total Harmonic Distortion) such as IEC 61000-3-2, IEEE 519 is being reinforced about a product which directly connects to AC line in order to prevent distortion of common power source in electronic equipment and electrical machinery. In order to satisfy these regulations, conventional circuits were used two-stage structure attached power factor correction circuit at ahead of converter but this method complicate the circuit and then a number of element increases thereupon the cost of production rises. in this paper, we propose a high efficiency single-stage 300W PFC fly-back converter that improved power factor and efficiency than conventional two-stage power module.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제48권12호
• /
• pp.691-700
• /
• 1999

This paper proposes a novel switching strategy of 1Mvar STATCON using cascade multilevel H-bridge inverter(HBI) for FACTS application. To control the reactive power instantaneously, the d-q dynamic system model is described and analyzed. A single pulse pattern based on the SHEM(Selective Harmonic Elimination Method) technique is determined from the look-up table to reduce the line current harmonics and a rotating fundamental frequency switching scheme is presented to adjust the DC voltage of each inverter capacitor at the same value. So the voltage unbalance problem between separately DC bus voltage is improved by using the proposed switching scheme. As a result, the presented inverter configuration not only reduces the system complexity by eliminating the isolation at the AC input side transformer but also improves the dynamic response to the step change of reactive power.

• Journal of Power Electronics
• /
• 제13권6호
• /
• pp.1058-1069
• /
• 2013

This paper proposes and designs a new output filter called an LCFL filter for application to three phase three wire shunt active power filters (SAPF). This LCFL filter is derived from a traditional LCL filter by replacing its capacitor with a C-type filter, and then constructing an L-C-type Filter-L (LCFL) topology. The LCFL filter can provide better switching ripple attenuation capability than traditional passive damped LCL filters. The LC branch series resonant frequency of the LCFL filter is set at the switching frequency, which can bypass most of the switching harmonic current generated by a SAPF converter. As a result, the power losses in the damping resistor of the LCFL filter can be reduced when compared to traditional passive damped LCL filters. The principle and parameter design of the LCFL filter are presented in this paper, as well as a comparison to traditional passive damped LCL filters. Simulation and experimental results are presented to validate the theoretical analyses and effectiveness of the LCFL filter.

• 조명전기설비학회논문지
• /
• 제20권5호
• /
• pp.25-32
• /
• 2006

본 논문에서는 전철시스템의 직류모선에 발생하는 잉여분의 전력을 교류전원 측으로 회생시킬 수 있는 회생인버터시스템을 제안한다. 제안된 직류 전철용 회생인버터 시스템은 교류 전원 측 전류에 포함되어진 고조파를 제거할 수 있는 기능을 추가하였다. 회생인버터 모드에서는 전철의 감속에 의해 회생되는 에너지를 재사용할 수 있으며, 능동전력필터 모드에서는 정류기에 의해 발생되는 고조파 왜곡을 보상할 수 있다. 논문에서 회생용 인버터는 PWM DC/AC 인버터 알고리즘을 사용하였으며, 능동전력필터는 p-q 이론을 사용하였다. 시뮬레이션은 축소모델[3.7kW]과 동일하게 구성되었다. 시뮬레이션과 실험 결과로부터 두 가지 알고리즘이 실 모델[100kW]에서도 적용되어질 수 있음을 증명하였다.

• 한국정보통신학회논문지
• /
• 제13권5호
• /
• pp.922-930
• /
• 2009

유도 전동기를 전압 제어하기 위한 최적 PWM 스위칭 방법을 제시하려한다. 전압 인버터의 공간 벡터 변조 방식은 DC-버스 이용을 향상시키고 정류 손실을 감소시키기 때문에 디지털 구현의 경우 특히 선호하는 PWM 방법이다. 유도 전동기 전압 제어를 위한 최적 PWM 스위칭 방법은 제시한 최적 PWM 알고리즘을 사용하여 두 개의 활성 전압 벡터(active voltage vector)와 하나의 영 전압 벡터(zero voltage vector)로 구성하였다. 선택된 스위칭 순차 열은 변조 지수(modulation index)와 운송파(carrier wave) 주기의 함수로 정의 된다. 순차 열은 인버터 스위칭 손실과 전류 리플 값을 기준으로 사용하여 선택된다. 실험 결과 중 저 전력용으로 사용할 경우 스위칭 주파수를 증가시킴에 따라 고조파 왜곡이 감소하고 동특성이 좋아짐을 확인할 수 있었다.

• Journal of Power Electronics
• /
• 제10권6호
• /
• pp.749-761
• /
• 2010

The switching frequency of a power device is a very important parameter in the design of a parallel active power filter (PAPF), but so far, very little discussion has been conducted on it in a quantitative manner in previous publications. In this paper, an extensive analysis on the effects of the switching frequency on the performance of a PAPF is made, and a specification of the switching frequency values with different compensation results is presented. A first-order inertia element and a second-order oscillation element are considered as approximate models of a PAPF, respectively. The compensation characteristic for each order of harmonic current is obtained at different switching frequencies. Then, the THDs of each model for the system loads of a rectifier with resistance and inductance loads are proposed. The compensation results of a PAPF controlled as a first-order inertia element are better than those of a PAPF controlled as a second-order oscillation element. With two types of system loads which are rectifier with resistance and inductance loads and rectifier with resistance, inductance and capacitance loads, the THDs of the source current after compensation are presented with different switching frequencies. The compensation characteristics for the most widely used digital control system are investigated. The situation with an analog control is the theoretical characteristic and it is the best situation. The compensation characteristic of the digital control is worse than the compensation characteristic of the theoretical characteristic. Based on these analyses, the specifications of compensation characteristics with different switching frequencies are quite straightforward. Finally, a practical design example is studied to verify the application.

• Journal of Electrical Engineering and Technology
• /
• 제11권6호
• /
• pp.1714-1728
• /
• 2016

This paper presents improved harmonics extraction based on Adaptive Linear Neuron (ADALINE) algorithm for single phase photovoltaic (PV) shunt active power filter (SAPF). The proposed algorithm, named later as Improved ADALINE, contributes to better performance by removing cosine factor and sum of element that are considered as unnecessary features inside the existing algorithm, known as Modified Widrow-Hoff (W-H) ADALINE. A new updating technique, named as Fundamental Active Current, is introduced to replace the role of the weight factor inside the previous updating technique. For evaluation and comparison purposes, both proposed and existing algorithms have been developed. The PV SAPF with both algorithms was simulated in MATLAB-Simulink respectively, with and without operation or connection of PV. For hardware implementation, laboratory prototype has been developed and the proposed algorithm was programmed in TMS320F28335 DSP board. Steady state operation and three critical dynamic operations, which involve change of nonlinear loads, off-on operation between PV and SAPF, and change of irradiances, were carried out for performance evaluation. From the results and analysis, the Improved ADALINE algorithm shows the best performances with low total harmonic distortion, fast response time and high source power reduction. It performs well in both steady state and dynamic operations as compared to the Modified W-H ADALINE algorithm.

• 한국조명전기설비학회지:조명전기설비
• /
• 제7권2호
• /
• pp.36-40
• /
• 1993

본 논문에서는, 고조파 제거를 위해 PWM 기법을 사용할 때 회로의 구성이 복잡해지고, 제어가 어렵다는 단점을 개선하기 위하여 기준 신호와 부하의 기준 모델(Model)에서 유도된 궤환 신호를 폐루프 처리하여 비교함으로써 인버터의 게이팅 신호를 발생하는 MRA(Model Reference Adaptive)PWM 기법을 제시하였고, 제어기의 구성을 마이크로프로세서 및 아나로그 회로로 설계하였다. 일반적인 정현 PWM 기법을 사용했을 경우, PWM기법을 이용하여 전원에 대한 출력 전압의 비가 낮기 때문에 발생되는 전압 이용율 저하를 MRA PWM 기법을 이용하여 보상할 수 있었다. 또한 사다리꼴(Trapezoidal) 신호를 기준 신호로 사용함으로써 선전류의 저차 고조파를 줄일 수 있었으며, 비교적 간단한 수식을 이용하여 실시간 계산(On-line computation)으로 스위칭 패턴을 발생하였다.