Power Factor Correction Operation Research Articles

낮은 120Hz 출력 전류 리플을 갖는 역률개선 LED 구동 회로

Recently, the LED(Light Emitting Diode) is expected to replace conventional lamps including incandescent, halogen and fluorescent lamps for some general illumination application, due to some obvious features such as high luminous efficiency, safety, long life, environment-friendly characteristics and so on. To drive the LED, a single stage PFC(Power Factor Correction) flyback converter has been adopted to satisfy the isolation, PFC and low cost. The conventional flyback LED driver has the serious disadvantage of high 120Hz output current ripple caused by the PFC operation. To overcome this drawback, a new PFC flyback with low 120Hz output current ripple is proposed in this paper. It is composed of 2 power stages, the DCM(Discontinuous Conduction Mode) flyback converter for PFC and BCM(Boundary Conduction Mode) boost converter for tightly regulated LED current. Since the link capacitor is located in the secondary side, its voltage stress is small. Moreover, since the driver is composed of 2 power stages, small output filter and link capacitor can be used. Especially, since the flyback is operated at DCM, the PFC can be automatically obtained and thus, an additional PFC IC is not necessary. Therefore, only one control IC for BCM boost converter is required. To confirm the validity of the proposed converter, theoretical analysis and experimental results from a prototype of 24W LED driver are presented.

Power quality improvements in power factor correction Luo converter fed brushless direct current motor drive

Summary This paper presents a power factor correction (PFC) Luo converter based voltage source inverter (VSI) fed brushless direct current (BLDC) motor drive using a single voltage sensor. A single-phase diode bridge rectifier followed by a Luo converter operating in discontinuous inductor current mode (DICM) is used for the direct current link voltage control and PFC operation at alternating current (AC) mains. The speed control is achieved by varying the direct current link voltage of VSI and electronically commutating the BLDC motor using fundamental frequency switching of VSI for reduced switching losses. The proposed PFC-based Luo converter fed BLDC motor drive is designed, and its performance is simulated and validated experimentally for achieving a unity power factor at AC mains over a wide range of speed control at universal AC mains. The achieved power quality indices are observed under the acceptable limits of international power quality standard such as IEC 61000-3-2. Copyright © 2014 John Wiley & Sons, Ltd.

Power-Quality Improvement in PFC Bridgeless SEPIC-Fed BLDC Motor Drive

Abstract This article presents a design of a power factor correction (PFC)-based brushless DC (BLDC) motor drive. The speed control of BLDC motor is achieved by controlling the DC link voltage of the voltage source inverter (VSI) feeding BLDC motor using a single voltage sensor. A front-end bridgeless single-ended primary inductance converter (SEPIC) is used for DC link voltage control and PFC operation. A bridgeless SEPIC is designed to operate in discontinuous inductor current mode (DICM) thus utilizing a simple control scheme of voltage follower. An electronic commutation of BLDC motor is used for VSI to operate in a low-frequency operation for reduced switching losses in the VSI. Moreover, a bridgeless topology offers less conduction losses due to absence of diode bridge rectifier for further increasing the efficiency. The proposed BLDC motor drive is designed to operate over a wide range of speed control with an improved power-quality at the AC mains under the recommended international power-quality standards such as IEC 61000–3-2.

An Intelligent Control Strategy for Power Factor Compensation on Distorted Low Voltage Power Systems

Due to the proliferation of harmonic producing-loads, harmonic resonance has become a major hurdle for performing power factor compensation in commercial power systems, such as office towers and shopping complexes. This paper presents an intelligent power factor compensation controller that can perform power factor correction without exciting harmonic resonance under varying demand conditions. Practical and robust control algorithms are proposed for the purpose of easy implementation in a micro-controller. In addition, the controller relies on common low cost sensing devices and does not require additional measurements. As a result, the proposed controller can be constructed as a retrofitting device to replace existing power factor correction controllers with little effort. Analysis of representative case studies is conducted to illustrate how the proposed controller performs.

Design-Oriented Analysis and Performance Evaluation of Buck PFC Front End

In universal-line ac/dc converters that require power factor correction (PFC), maintaining a high efficiency across the entire line and load ranges poses a major challenge. Typically, a boost PFC front end exhibits 1%-3% lower efficiency at 100-V line compared to that at 230-V line. It is shown in this paper that a buck PFC front end with an output voltage in the 80-V range can maintain a high efficiency across the entire line and load ranges. A thorough analysis of the buck PFC converter operation and performance along with design optimization guidelines are presented. Experimental results obtained on a 90-W notebook adapter are provided. A loss analysis based on SIMPLIS and PSPICE simulations is also included. Major factors that contribute to the improved efficiency of the buck PFC versus the boost PFC are briefly explained.

Performance Comparison of Single-Stage Three-Level Resonant AC/DC Converter Topologies

In this paper, the performance of different three-level resonant converters is studied for single-stage power factor correction operation. These converters are suitable for power ranges higher than that in the currently available single-stage converters, due to their high efficiency and reduced component stresses. All the converters presented here are characterized by their ability to regulate the output voltage as well as the dc bus voltage. This leads to lower voltage stresses, wider input voltage range, higher output power applications, and improved efficiencies compared to existing single-stage topologies. Due to the availability of more degrees of freedom in the presented converters, two types of control strategies can be used for this purpose: variable frequency asymmetrical pulsewidth modulation control and variable frequency phase-shift modulation control. Three resonant converters will be studied in this paper and their performances as well as the applicability of the aforementioned control methods for each converter are compared. A 2.3-kW, 48-V converter with input voltage range of 90-265 Vrms is used to study the performance of each case.

Transformerless three-phase on-line UPS with high performance

A transformerless three-phase on-line uninterruptible power supply (UPS) is proposed. The proposed UPS is composed of a rectifier, an inverter and a battery charger/discharger. The rectifier regulates a DC-link voltage and performs power factor correction. On the other hand, the inverter provides a regulated sinusoidal output voltage and has the current-limiting capability for an impulsive load. The battery charger/discharger reduces the number of battery and supplies the power demanded by the load in the event of the input power failure or abrupt decrease of the input voltage. Since both neutral lines of the input and output voltages are connected at the centre of the DC-link, the need for an isolation transformer is eliminated and the size, weight and cost of the system are significantly reduced. Additionally, new control algorithms of the rectifier, the charger/discharger and the inverter are proposed.

Performance Comparison of Single-Stage Three-Level Resonant AC/DC Converter Topologies

In this paper, the performance of different three-level resonant converters is studied for single-stage power factor correction operation. These converters are suitable for power ranges higher than that in the currently available single-stage converters, due to their high efficiency and reduced component stresses. All the converters presented here are characterized by their ability to regulate the output voltage as well as the dc bus voltage. This leads to lower voltage stresses, wider input voltage range, higher output power applications, and improved efficiencies compared to existing single-stage topologies. Due to the availability of more degrees of freedom in the presented converters, two types of control strategies can be used for this purpose: variable frequency asymmetrical pulsewidth modulation control and variable frequency phase-shift modulation control. Three resonant converters will be studied in this paper and their performances as well as the applicability of the aforementioned control methods for each converter are compared. A 2.3-kW, 48-V converter with input voltage range of 90-265 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> is used to study the performance of each case.

EFFECT OF THE RIPPLE CURRENT ON POWER FACTOR OF CRM BOOST APFC

Boost Active Power Factor Corrector operating in a Borderline or Critical Conduction Mode is reexamined. Approximate analytical expressions of the inductor RMS current as well as estimation of Power Factor of the APFC are obtained. Based on the proposed theory, the paper suggests simple design criteria for the line filter.

Limits in boost power factor corrector operating in border-line mode

The single-phase boost power factor correctors may operate in the so called border-line mode, which is distinguished by variable switching frequency. If some constraints are imposed on variability of this frequency some limits to output voltage and power of the circuit appear at once. The paper shows the origin of them and presents formulas and graphs helpful in a proper choice of circuit parameters in order to keep the switching frequency within a predefined range, also under the changes of input line voltage and of the load resistance.

Single-stage SVS PWM full-bridge converter

A new soft-switched ac-dc single-stage pulse width modulation (PWM) full-bridge converter is proposed. The converter operates with zero-voltage switching (ZVS), fixed switching frequency, and with a continuous input current that is sinusoidal and in phase with the input voltage. This is in contrast with other ac-dc single-stage PWM full-bridge converters that are either resonant converters operating with variable switching frequency control and high conduction losses, converters whose switches cannot operate with ZVS, or converters that cannot perform power factor correction (PFC) unless the input current is discontinuous. All converter switches operate with soft-switching due to a simple auxiliary circuit that is used for only a small fraction of the switching cycle. The operation of the converter is explained and analyzed, guidelines for the design of the converter are given, and its feasibility is shown with results obtained from an experimental prototype.

불연속 전류모드로 동작하는 Interleaved 승압형 역률보상 컨버터의 입력전류 리플개선

본 논문에서는 SMPS의 교류 입력측 역률을 개선시킬 수 있는 전치 레귤레이터로서 interleaved 승압형 컨버터를 관하여 연구하였다. Interleaved 승압형 역률보상 컨버터(IBPFC)는 입력전류를 두 개의 스위칭 소자에 의하여 50%씩 나누어져 흐르게 함으로써, 내부 전류제어 루프 없이 전압제어 루프만으로 제어계를 구성하여 입력전류 리플을 줄일 수 있다. 즉, IBPFC를 구성하는 각각의 부스트 컨버터 cell을 불연속 전류모드로 동작시키더라도 전체적인 입력전류의 파형은 연속이 되어 입력전류 리플이 감소하게 된다. 불연속 전류모드로 동작하는 IBPFC를 해석하기 위하여 스위칭 상태에 따라서 6개의 모드로 구분하여 상태방정식을 구하였다. 또한, 각 상태방정식을 상태공간 평균화법을 이용하여 모델링하고, 미소변동분을 고려한 소신호 해석을 통하여 제어전달함수를 구할 수 있다. 또한, 제어전달함수를 이용하여 단일 전압제어 루프를 가지는 제어계를 설계하였으며, 이러한 해석 및 설계를 바탕으로 실험을 통하여 IBPFC의 역률개선 및 리플저감을 확인하였다.

Bi-directional single-phase half-bridge rectifier for power quality compensation

A single-phase half-bridge rectifier with a capacitor clamped scheme is proposed. Four power switches and one flying capacitor are employed in the proposed rectifier. Bipolar and unipolar PWM control schemes are used to perform power factor correction and achieve low total harmonic distortion of line current. A neutral point voltage balance compensator, hysteresis current controller and DC link voltage regulator are used to balance neutral point voltage, to track line current command, and to maintain the constant DC bus voltage. The proposed control scheme and the circuit configuration can also perform a shunt active power filter operation to eliminate the harmonic currents and compensate the reactive power generated from the nonlinear load. Analytical and experimental results are presented to illustrate the validity and effectiveness of the proposed control scheme.

Output voltage and power limits in boost power factor corrector operating in discontinuous inductor current mode

In this paper, there is shown the existence of limits to output voltage and power in a boost power factor correcting circuit operating in discontinuous inductor current mode. Like in the continuous case, the limits result from input current distortions that appear when the output power and voltage are not chosen properly for given circuit elements. There are presented graphs and numerical data which allow determining the proper values of circuit parameters and elements to ensure the proper operation of the whole circuit.

Three-phase buck/boost-type high-power-factor switching converter

The harmonic pollution caused by ac-to-dc converters has been of great concern. To overcome this problem, several power-factor-correction (PFC) converters have been developed and applied in recent years. However, several power converter systems, such as the motor drive system, with a wide V/F control range, uninterruptible power supply system and dc power supply system with universal input voltage range, require an ac-to-dc converter or an off-line converter (preregulator) with a wide output-voltage control range in order to be highly efficient. However, the most conventional PFC converters employ a voltage-fed or current-fed type topology and they have a lower or upper limitation of the output-voltage control range. Thus, they do not realize sufficiently high-system efficiency. On the other hand, a buck/boost converter has a wide control range of the output voltage and acts in PFC operation under an appropriate control technique. Thus, study of the possibility of using the buck/boost ac-to-dc converter with PFC and a wide output-voltage control range is important to the realization of harmonic-free and efficient power conversion systems. In this paper, the author proposes a three-phase bridge-type ac-to-dc converter system with a high input power factor and a wide output-voltage control range. The controller of the proposed system includes the following two new techniques. One is the pulse integral value modulation that compensates modulation errors in conventional pulse-width-modulation caused by dc current ripples or fluctuations of the current pulse amplitude. The other is a switching pulse pattern generator, using the idea of equivalent pulse current source for the bridge as a way to simplify the pulse pattern generation process. This paper describes the proposed converter system, the control and modulation principles, and experimental results that show the reliability and usefulness of the proposed buck/boost converter system. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (2): 41–55, 1997

Three‐phase buck/boost‐type high‐power‐factor switching converter

The harmonic pollution caused by ac-to-dc converters has been of great concern. To overcome this problem, several power-factor-correction (PFC) converters have been developed and applied in recent years. However, several power converter systems, such as the motor drive system, with a wide V/F control range, uninterruptible power supply system and dc power supply system with universal input voltage range, require an ac-to-dc converter or an off-line converter (preregulator) with a wide output-voltage control range in order to be highly efficient. However, the most conventional PFC converters employ a voltage-fed or current-fed type topology and they have a lower or upper limitation of the output-voltage control range. Thus, they do not realize sufficiently high-system efficiency. On the other hand, a buck/boost converter has a wide control range of the output voltage and acts in PFC operation under an appropriate control technique. Thus, study of the possibility of using the buck/boost ac-to-dc converter with PFC and a wide output-voltage control range is important to the realization of harmonic-free and efficient power conversion systems. In this paper, the author proposes a three-phase bridge-type ac-to-dc converter system with a high input power factor and a wide output-voltage control range. The controller of the proposed system includes the following two new techniques. One is the pulse integral value modulation that compensates modulation errors in conventional pulse-width-modulation caused by dc current ripples or fluctuations of the current pulse amplitude. The other is a switching pulse pattern generator, using the idea of equivalent pulse current source for the bridge as a way to simplify the pulse pattern generation process. This paper describes the proposed converter system, the control and modulation principles, and experimental results that show the reliability and usefulness of the proposed buck/boost converter system. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (2): 41–55, 1997

Three-Phase Buck/Boost-type High-Power-Factor Switching Converter.

The harmonic pollution caused by ac-to-dc converters has been our great concern. To overcome the problem, several Power-Factor-Correction (PFC) converters have been developed and applied in practice in recent years.However, several power converter systems, such as motor drive system with a wide V/F control range, uninterruptible power supply system, and dc power supply system with an universal input voltage range, require an ac-to-dc converter or an off-line converter (pre-regurator) with a wide output-voltage control range to obtain high efficiency. But the most conventional PFC converters employ a Voltage-Fed or Current-Fed type topology and they have lower or upper limitation of the output-voltage control range. Thus, they do not realize sufficiently high system efficiency.On the other hand, a Buck/Boost converter has a wide control range of the output voltage and acts PFC operation under an appropriate control technique. Thus, the study of a possibility about the Buck/Boost ac-to-dc converter with PFC and a wide output-voltage control range is important to realize harmonic-free and efficient power conversion systems.In this paper, the author proposes a three-phase bridge-type ac-to-dc converter system with a high input power factor and a wide output-voltage control range. The controller of the proposed system includes following two new techniques. One is the “Pulse-Space-Modulation” to compensate modulation errors in conventional Pulse-Width-Modulation caused by dc current ripples or fluctuations of the current pulse amplitude. The other is a switching pulse pattern generator, using the idea of equivalent pulse current source for the bridge, to simplify the pulse pattern generation process.In the following, the paper describes the proposed converter system, the control and modulation principles, and experimental results that show the reliability and usefulness of the proposed Buck/Boost converter system. Finally, the paper concludes the contents of this paper.