Achieve Power Factor Correction Research Articles

Analysis, Design and Implementation of an Interleaved Single-Stage AC/DC ZVS Converters

An interleaved single-stage AC/DC converter with a boost converter and an asymmetrical half-bridge topology is presented to achieve power factor correction, zero voltage switching (ZVS) and load voltage regulation. Asymmetric pulse-width modulation (PWM) is adopted to achieve ZVS turn-on for all of the switches and to increase circuit efficiency. Two ZVS half-bridge converters with interleaved PWM are connected in parallel to reduce the ripple current at input and output sides, to control the output voltage at a desired value and to achieve load current sharing. A center-tapped rectifier is adopted at the secondary side of the transformers to achieve full-wave rectification. The boost converter is operated in discontinuous conduction mode (DCM) to automatically draw a sinusoidal line current from an AC source with a high power factor and a low current distortion. Finally, a 240W converter with the proposed topology has been implemented to verify the performance and feasibility of the proposed converter.

Techniques to obtain single-stage power supplies with power factor correction (PFC)

In order to comply with the standards, the input current of the switch mode power supplies (SMPS) must be almost sinusoidal, i.e. the SMPS must achieve power factor correction. This requirement is normally reached with the use of an additional input converter, typically a boost, resulting in a two-stage SMPS with the inherent drawbacks: high cost and the necessity of high efficiency in each stageto obtain a reasonable global efficiency. This article introduces two simple techniques together with the control strategies that can be used to obtain single-stage SMPS, that allow the control of the output voltage and the sinusoidal input current wave shaping, without any additional stage. Another objective of this article is to investigate and to evaluate the performance of each topology that emerged from the chosen technique. Considering high-power applications, experimental results of two single-stage full-bridge topologies are also presented, in order to verify the concepts introduced in the article.

Single-Stage AC/DC Boost–Forward Converter With High Power Factor and Regulated Bus and Output Voltages

Unlike existing single-stage AC/DC converters with uncontrolled intermediate bus voltage, a new single-stage AC/DC converter achieving power factor correction (PFC), intermediate bus voltage output regulation, and output voltage regulation is proposed. The single-power-stage circuit is formed by integrating a boost PFC converter with a two-switch-clamped forward converter. The current stress of the main power switches is reduced due to separated conduction period of the two source currents flowing through the power switch. A dual-loop peak-current-mode controller is proposed to achieve PFC and ensure independent bus voltage and output voltage regulations. Experimental results on a 24-V/100-W hardware prototype are given to confirm the theoretical analysis and performance of the proposed converter. The converter has conversion efficiency ranging from 86% to 92% at full-load condition.

ON CONTROL OF INTERMEDIATE CAPACITOR VOLTAGE IN SINGLE-STAGE AC/DC PFC CONVERTER

To reduce the intermediate storage capacitor voltage stress in single-stage power-factor-corrected (S2PFC) converters due to the change of load, some effective approaches such as variable frequency control and negative bus voltage feedback have been proposed. However, this intermediate capacitor voltage still varies largely against the change of line voltage. This paper proposes a S2PFC converter which is constructed in a way such that the amount of energy to and from the intermediate storage capacitor can be varied when the line voltage is changed, hence narrowed the range of intermediate capacitor voltage fluctuation. This is achieved by an auxiliary bidirectional switch, which operates at zero-voltage-switching (ZVS) condition. A dual-loop voltage mode control is proposed for the converter to achieve power factor correction, output voltage regulation, and intermediate capacitor voltage control simultaneously. Simulation and experimental results show that the proposed approach is effective.

A Single-Stage AC/DC Converter With High Power Factor, Regulated Bus Voltage, and Output Voltage

Unlike existing single-stage AC/DC converters with uncontrolled intermediate bus voltage, a new single-stage AC/DC converter achieving power factor correction (PFC), intermediate bus voltage output regulation, and output voltage regulation is proposed. The converter is formed by integrating a boost PFC converter with a two-switch clamped flyback converter into a single power stage circuit. The current stress of the main power switch is reduced due to separated conduction period of the two source currents flowing through the power switch. A dual-loop current mode controller is proposed to achieve PFC, and ensure independent bus voltage and output voltage regulations. Experimental results on a 24-V/100-W hardware prototype are given to confirm the theoretical analysis and performance of the proposed converter.

Integrated Zeta–Flyback Electronic Ballast to Supply High-Intensity Discharge Lamps

This paper proposes a metal halide lamp electronic ballast based on the integration of zeta and flyback converters, which are used to achieve power factor correction and lamp current stabilization, respectively. The proposed integrated converter allows to reduce the number of ballast components without increasing the current stress in the shared switch. Thus, the lamp is supplied with a low-frequency square waveform that avoids the acoustic resonance phenomenon. The proposed topology has been implemented and validated by experimental results.

Single-phase unidirectional AC∕DC converter with high power factor

A novel single-phase unidirectional power flow rectifier is proposed to achieve power factor correction and DC bus voltage regulation. Four active switches, two power diodes and two DC side capacitors are used in the proposed circuit topology to generate a three-level PWM voltage waveform on the ac terminal of the proposed rectifier. Compared with neutral-point-clamped and capacitor-clamped topologies, no clamping diode or flying capacitor is used in the proposed rectifier. The reference line current is derived from the DC tank voltage controller and a sinewave generator in phase with mains voltage. The carrier-based current controller is used in the inner loop to track the line current command. A neutral-point voltage compensator is adopted in the control scheme such that the capacitor voltages on the DC side are balanced. The effectiveness of the proposed control algorithm is verified by the computer simulations and experimental results.

Single-phase switching-mode rectifier with capacitor-clamped topology

A single-phase switching-mode rectifier with capacitor-clamped topology is presented to achieve power factor correction, eliminate current harmonic, draw a sinusoidal line current from the AC source and maintain the DC-link voltage constant. The proposed switching-mode rectifier has the capability of bidirectional power flow. Six active switches and one clamping capacitor are used in the rectifier to achieve the three-level pulse-width-modulated operation. A carrier-based current controller is adopted in the inner loop to track the reference line current. To regulate the DC bus voltage constant, a voltage controller based on a proportional–integral scheme is used in the outer loop. A voltage self-balancing technique is adopted in the control scheme to balance the capacitor voltages. Based on the proposed control scheme, a three-level pulse-width-modulated waveform is generated on the AC terminal of the rectifier. The proposed control algorithm illustrates its validity and effectiveness through computer simulation and experimental results.

REDUCTION OF CURRENT AND VOLTAGE STRESSES IN SINGLE-STAGE AC/DC POWER FACTOR CORRECTION CONVERTERS WITH REDUCED REPEATED POWER PROCESSING AND INHERENT INPUT CURRENT CONTROL

In this paper, a new family of single-stage AC/DC power factor correction converters (S2PFCC), which possesses reduced voltage stress across the storage capacitor and no extra current stress on the power switch, is proposed. The converters are realized by reduced repeated power processing concept in which part of the input power is transferred to the load directly after the first power process. This results in lower storage capacitor voltage than that of previously developed S2PFCCs but maintaining high power factor. In addition, the inherent input current control allows the load current to reduce the input line current automatically when the load becomes light, preventing excessive amount of energy being stored in the storage capacitor. Although the proposed converters employed two power switches, a simple single-loop controller for the proposed S2PFCC to achieve power factor correction (PFC) and tight output regulation is also proposed. Experimental results are reported to verify the operation and concept of the new S2PFCC.

Single-phase half-bridge rectifier with power factor correction

A single-phase half-bridge switching mode rectifier is presented to draw a sinusoidal line current, to achieve power factor correction and to maintain the DC-link voltage constant. Four active switches are used in the proposed rectifier to generate a unipolar pulse width modulation (PWM) voltage waveform on the AC terminal voltage. There is no clamping diode in the proposed rectifier (as compared with the neutral point clamped (NPC) converter) so as to achieve three-level PWM operation. Two control loops are used in the proposed control scheme. In the outer control loop, a proportional integral voltage controller is used to regulate the DC-link voltage. A phase lock loop circuit is adopted to generate a sinusoidal waveform in phase with mains voltage to achieve power factor correction. In the inner control loop, a carrier-based current controller is used to track the line current command. To compensate the neutral point voltage due to the load variation, a neutral point voltage compensator is used in the control scheme. Three voltage levels are generated on the AC terminal of the adopted rectifier. Computer simulations and experimental results are presented to verify the effectiveness of the proposed control algorithm.

Circuit theory of power factor correction in switching converters

AbstractThis paper discusses the circuit theory aspects of power factor correction in switching converter circuits. The discussion begins with an examination of the requirement of power factor correction in dc/dc converters. Using the concept of zero‐order converter circuits, sufficient conditions for a dc/dc converter circuit to provide power factor correction are derived. The duality principle is applied to generate new converter circuits that can achieve power factor correction. The practical application of power factor correction is considered in conjunction with the requirement of tight output voltage regulation. Detailed study of the circuit configuration that can simultaneously provide power factor correction and output regulation is given. Based on a general three‐port model, the voltage regulator with power factor correction capability is studied in terms of the power flow between the input port, output port and energy storage port. A detailed consideration of the power flow among the three ports leads to the derivation of all possible minimal configurations that can achieve power factor correction and voltage regulation. The efficiencies of these minimal configurations are studied theoretically, leading to the concept of ‘reduced redundant power processing’ which provides important clue to efficiency improvement. Another issue addressed in this paper is the synthesis of practical circuits that can provide power factor correction and output regulation. In particular, four practical minimal configurations that achieve reduced redundant power processing are considered. A systematic synthesis procedure is derived for creating converter circuits that achieve power factor correction and output voltage regulation. The control issue is also investigated in depth, pinpointing the basic requirement on the number of control parameters needed and its relationship with the operating mode. Copyright © 2003 John Wiley & Sons, Ltd.

A family of PFC voltage regulator configurations with reduced redundant power processing

This paper discusses a systematic method for deriving basic converter configurations that achieve power factor correction (PFC) and voltage regulation. The discussion begins with a general three-port representation of power supplies that provide PFC and voltage regulation. Based on this representation and a power flow consideration, a systematic procedure is derived to generate all possible minimal configurations. Among these configurations, only a few have been known previously and used in practice. It is found that the efficiency of PFC voltage regulators can be improved by reducing the amount of redundant power to be processed by the constituent converters. A systematic circuit synthesis procedure is proposed for creating PFC voltage regulators with reduced redundant power processing. Experimental measurements verify the improved efficiency.

Simplified control method for single-phase multilevel active rectifier with current harmonic filtering characteristics

The active power filter is an important way to reduce reactive power and harmonic currents from nonlinear loads. A simple control strategy is presented which employs an active rectifier, based on neutral point clamped topology, to work simultaneously as an active power filter to decrease current harmonics. The system power factor is also compensated in the proposed control algorithm. The active rectifier forces the mains current to be sinusoidal and in phase with the mains voltage. A voltage source rectifier, with carrierless hysteresis PWM current control, is used in the inner loop control. A simple PI DC-link voltage controller is adopted in the outer loop control. The control strategy of the adopted active rectifier is based on a look-up table to reduce the cost and required hardware. The proposed scheme can achieve power factor correction, without complicated calculations for harmonic elimination and without a dedicated active power filter. A diode rectifier-fed capacitive load as the nonlinear load is taken on the AC mains to demonstrate the effectiveness of the proposed active rectifier for reactive power and harmonic compensation.

Theoretical study of switching power converters with power factor correction and output regulation

This paper discusses a systematic method for deriving basic converter configurations that achieve power factor correction (PFC) and voltage regulation. The discussion begins with a general three-port representation of power supplies that provide PFC and voltage regulation. Based on this representation and a power flow consideration, a systematic procedure is derived to generate all possible minimal configurations. It is found that two basic converters are, in general, required for implementing any of the possible configurations. Among these configurations only a few have been known previously and been used in practice. The various possible configurations are compared in terms of their theoretical efficiency and control requirements of the basic constituent converters.

Start-up inrush current elimination control of new push-pull quantum series resonant rectifier

A combined buck and boost push-pull quantum series resonant rectifier (PPQSRR) is newly proposed to achieve power factor correction without start-up inrush current. With the proposed control method and circuitry, a high power factor and wide range of output voltage without an inrush current can be obtained.