• 제목/요약/키워드: Unity power factor

검색결과 326건 처리시간 0.026초

정밀 열전형변환기를 사용한 기준직교류전력비교기 (Reference DC/AC Power comparator on the basis of precision thermal converters)

  • 박영태;장석명
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1995년도 하계학술대회 논문집 B
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    • pp.676-678
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    • 1995
  • The Paper describes a dc/nc power comparator for measurement of power. Based on a thermal principle, the instrument performs ac-dc transfer and absolute power and energy measurements in the range of currents from 0 to 5 A, voltages from 60 to 240 V, power factors from 0 to 1 and frequencies from 50 to 1000 Hz. The ac-dc transfer accuracy is better than 20 ppm at unity power factor and better than 50 ppm at 0.5 power factor.

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A Novel Photovoltaic Power Harvesting System Using a Transformerless H6 Single-Phase Inverter with Improved Grid Current Quality

  • Radhika, A.;Shunmugalatha, A.
    • Journal of Power Electronics
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    • 제16권2호
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    • pp.654-665
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    • 2016
  • The pumping of electric power from photovoltaic (PV) farms is normally carried out using transformers, which require heavy mounting structures and are thus costly, less efficient, and bulky. Therefore, transformerless schemes are developed for the injection of power into the grid. Compared with the H4 inverter topology, the H6 topology is a better choice for pumping PV power into the grid because of the reduced common mode current. This paper presents how the perturb and observe (P&O) algorithm for maximum power point tracking (MPPT) can be implemented in the H6 inverter topology along with the improved sinusoidal current injected to the grid at unity power factor with the average current mode control technique. On the basis of the P&O MPPT algorithm, a power reference for the present insolation level is first calculated. Maintaining this power reference and referring to the AC sine wave of bus bars, a sinusoidal current at unity power factor is injected to the grid. The proportional integral (PI) controller and fuzzy logic controller (FLC) are designed and implemented. The FLC outperforms the PI controller in terms of conversion efficiency and injected power quality. A simulation in the MATLAB/SIMULINK environment is carried out. An experimental prototype is built to validate the proposed idea. The dynamic and steady-state performances of the FLC controller are found to be better than those of the PI controller. The results are presented in this paper.

3상 Single Stage 방식의 48V/100A급 고효율 고역률 직류 전원장치 (High efficiency and power factor 48V/100A DC power supply of three-phase single stage method)

  • 박진영;김경환
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2005년도 전력전자학술대회 논문집
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    • pp.430-432
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    • 2005
  • This paper presents a novel, single stage, isolated, three-phase switching rectifier capable of switching at high frequency. The circuit topology Provides zero-voltage switching for all switches, output voltage regulation, unity input power factor, all in a single power conversion stage. Operating principle and experimental results in the 48V/100A DC power supply of three-phase single stage method are presented.

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단위 역률을 갖는 3상 강압형 다이오드 정류기에서 고조파 주입에 의한 DC 리플전압 저감 기법 (A DC Ripple Voltage Suppression Scheme by Harmonic Injection in Three Phase Buck Diode Rectifiers with Unity Power Factor)

  • 고종진
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 2000년도 전력전자학술대회 논문집
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    • pp.305-308
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    • 2000
  • A technique to suppress the low frequency ripple voltage of the DC output in three phase buck diode rectifiers is presented in this paper. The proposed pulse frequency modulation methods and duty ratio modulation methods are employed to regulate the output voltage of the buck diode rectifiers and guarantee zero-current -switching(ZCS) of the switch over the wide load range The proposed control methods used in this paper provide generally good performance such as low THD of the input line current and unity power factor. IN addition control methods can be effectively used to suppress the low frequency ripple voltage appeared in the dc output voltage. The harmonic injection technique illustrates its validity and effectiveness through the simulations.

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유도가열 시스템을 위한 새로운 전류형 풀-브릿지 공진형 인버터 설계 (Design of New Current Full-Bridge Resonant Inverter for Induction Heating System)

  • 이상훈;임상길;송성근
    • 조명전기설비학회논문지
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    • 제26권7호
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    • pp.59-69
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    • 2012
  • There are two types of inverters that are generally used in induction heating systems: voltage type inverters and high-frequency half-bridge inverters. This paper proposes a new resonant inverter for induction heating systems using the current type full-bridge method. The proposed method can remove capacitors at the input end, and enables unity power factor operation by preventing phase differences of voltage and current. Furthermore, Zero Voltage Switching (ZVS) which is in tune with current type inverter can be adopted and continuous power adjustment is possible through duty ratio changes and frequency modulation in switching operation. Simulations and experiments showed that the proposed current type full-bridge resonant inverter could be used for unity power factor control and ZVS operation in induction heating systems.

전류오차 백터 제어방식에 의한 새로운 형태의 전류 제어 PWM 전압형 정류기 (Novel Current Controlled PWM-VSC Converter Using Current Error Vector Control)

  • 박민호;최재호
    • 대한전기학회논문지
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    • 제38권4호
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    • pp.261-268
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    • 1989
  • A novel current controlled PWM voltage source type converter and control strategy is proposed that is able to draw nearly sinusoidal current at unity power factor from three phase power lines. Current error vector control scheme is used which has two operating states : low harmonic current content state and quick current response state. The state is changed according to the current error to optimize the steady state and transient state performances. To regulate the dc oupput voltage, the magnitude of the reference current is determined by a controller dc voltage error. The ac input power factor can be controlled with unity, and even leading or lagging by adjusting the relative position of the reference current with respect to the supply voltage.

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자기결합 무손실 스너버를 갖는 새로운 고역률 단일전력단 AC/DC 컨버터 (Single-Stage Single-Switched AC/DC Converter with Magnetic Coupled Nondissipative Snubber)

  • 조정욱;문건우;정영석;윤명중
    • 전력전자학회:학술대회논문집
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    • 전력전자학회 1997년도 전력전자학술대회 논문집
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    • pp.423-431
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    • 1997
  • A new single-stage/single-switched forward converter with magnetic coupled nondissipa-tive snubber is proposed. The proposed converter gives the good power factor correction (PFC), low current harmonic distortion, and tight output voltage regulation. The prototype shows the IEC 555-2 requirements are met satisfactorily with nearly unity power factor. This proposed converter with magnetic coupled nondissipative snubber is particularly suited for low power level power supply applications.

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능동 클램프 모드로 동작하는 단일 전력 AC/DC 컨버터에 의한 역률개선 (Power Factor with Single Power Stage AC/DC Converter Operated in Active-Clamp Mode)

  • 윤신용;백수현;김용;김철진;어창진
    • 대한전기학회논문지:전기기기및에너지변환시스템부문B
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    • 제50권8호
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    • pp.392-401
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    • 2001
  • This paper presents the single-stage high power factor AC to DC converter operated in active-clamp mode. The proposed converter is added active-clamping circuit to boost-flyback single-stage power factor corrected power supply. The active-clamping circuit limits voltage spikes, recycles the energy trapped in the leakage inductance, and provides a mechanism for achieving soft switching of the electronic switches to reduce the switching loss. The auxiliary switch of active-clamping circuit uses the same control and driver circuit as the main switch to reduce the additional cost and size. To verify the performance of the proposed converter, a 100W converter has been designed. The proposed converter gives good power factor correction, low line current harmonic distortions, and tight output voltage regulation, as used unity power factor.

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Single-Stage High-Power-Factor Electronic Ballast with a Symmetrical Class-DE Resonant Rectifier

  • Ekkaravarodome, Chainarin;Jirasereeamornkul, Kamon
    • Journal of Power Electronics
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    • 제12권3호
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    • pp.429-438
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    • 2012
  • This paper presents the use of a novel, single-stage high-power-factor electronic ballast with a symmetrical class-DE low-$d{\upsilon}$/$dt$ resonant rectifier as a power-factor corrector for fluorescent lamps. The power-factor correction is achieved by using a bridge rectifier to utilize the function of a symmetrical class-DE resonant rectifier. By employing this topology, the peak and ripple values of the input current are reduced, allowing for a reduced filter inductor volume of the EMI filter. Since the conduction angle of the bridge rectifier diode current was increased, a low-line current harmonic and a power factor near unity can be obtained. A prototype ballast, operating at an 84-kHz fixed frequency and a 220-$V_{rms}$, 50-Hz line input voltage, was utilized to drive a T8-36W fluorescent lamp. Experimental results are presented which verify the theoretical analysis.

전류형 능동 교류 전력 필터의 해석 (Analysis of Current-Fed Active AC Power Filters)

  • Choe, Gyu-Ha
    • 대한전기학회논문지
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    • 제38권6호
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    • pp.441-450
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    • 1989
  • A control technique for current-fed filters is proposed which not only eliminates the harmonic current, but also controls the reactive power at the ac sides of PWM inverter-induction motor drive system. Injecting the proposed PWM current enables the harmonic components of orders not greater than the number of pulses per half-cycle to be removed completely. Also it enables the input fundamental power factor to become unity and hence total input power factor can be improved greatly. Digital simulation is performed to investigate the theoretical output characteristics of the current-fed filters by the proposed control technique.

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