Single-stage Power Factor Correction Converter Research Articles

Integrated Boost and Dual-Switch Forward Converters as Soft-Switching Single-Stage PFC Converter

Integrated Boost and Dual-Switch Forward Converters as Soft-Switching Single-Stage PFC Converter

Voltage-Mode Variable-Frequency Controlled LLC Resonant Power Factor Correction Converter and Its Accurate Numerical Calculation Analysis

LLC resonant converter is a good candidate for single-stage ac–dc converter, which can realize both functions of power factor correction (PFC) and output voltage regulation, and contribute to the improvement of conversion efficiency and power density. However, voltage mode (VM) controlled single-stage half-bridge LLC PFC converter has the disadvantages of large dead-zone of input current and hard-switching operation, since there is no current control. Besides, the voltage ripple of input filter brings asymmetrical operation of the converter between the positive and the negative half-switching cycle. In order to solve these problems, this article presents a modified numerical calculation method, which can realize accurate characterization of the asymmetrical behavior of resonant current and voltage. Based on that, the switching frequency of LLC resonant converter for unity power factor (PF) is derived. A method of fitting the switching frequency is proposed to simplify the circuit implementation. A 250-W/48-V prototype has been built to verify the analysis results. Experimental results show that the proposed voltage-mode variable-frequency (VM-VF) controlled LLC resonant PFC converter can achieve high efficiency of up to 94.08% and power factor of 0.95 over the input voltage range of 180–260 VAC.

Efficient Soft Switching Single-Stage PFC for Low-Power Applications

Single-stage (SS) power factor correction (PFC) converters are applied as the power supply for low-power devices. Usually, the flyback converter is merged with the PFC stage to eliminate the reset winding required for the transformer. This article merges a new resonant forward converter with the buck-boost PFC stage. Thus, reset winding of the forward converter is eliminated while soft switching is achieved. Due to the low flux of the forward transformer core, transformer volume is reduced. Also, for the same volume of the transformer, transformer losses can be reduced in comparison to the flyback converter. The proposed converter is analyzed, and design considerations are discussed. A prototype converter is implemented. According to the experimental results, high efficiency and low total harmonic distortion (THD) are achieved.

An off-line single-switch VLC transmitter for low data rate applications

This work details a single-stage flyback power factor correction (PFC) converter operating in discontinuous conduction mode (DCM) for visible light communication (VLC). The role of the converter is to regulate the average output current via the duty cycle value for lighting purposes and to modulate digital data by means of the first switching harmonic of the output current. Both features can be achieved simultaneously by modulating the PWM signal fed to the single switch of the flyback converter. In order to allow for the transmission of VLC data, the converter output low-pass filter has been replaced by a 3rd order band-stop (notch) filter and an additional feedforward loop was introduced. This strategy maintains the simplicity of the original topology while granting it the functionality of transmitting VLC data with a reduced component count. Experimental results taken from a 14-W prototype supplied from a 127-V 60-Hz grid were carried out in order to verify the modulation scheme and the feasibility of the VLC transmitter, which was able to transfer data with a bit rate of 15 kb/s over a distance of 2 m with a global efficiency of 93.3% while keeping a good input power factor.

High performance single stage power factor correction circuit

Here, a new single stage single switch soft switching PFC (power factor correction) converter is presented and analysed. The proposed converter combines buck AC-DC converter and forward DC-DC converter and applies an auxiliary circuit to eliminate input current dead angle. Furthermore, soft switching is attained and switching losses are eliminated resulting in high efficiency. Another merit of the proposed converter is the partial direct transmission of input power to the output that helps to improve efficiency. Experimental results are presented which justify the above mentioned points and show less than 5% THD in the nominal load. Comparison with other similar single stage PFC converters is performed and shows the proposed converter provides the lowest THD while high efficiency is attained.

Single-Phase LED Driver With Reduced Power Processing and Power Decoupling

Reduced power processing is a new trend to improve the conversion efficiency of light-emitting diode (LED) driver systems. Based on the concept, a new LED driver architecture is proposed in this article, which requires fewer power semiconductors compared with prior works, leading to the potential of lower cost and higher efficiency. A new ac/dc LED driver topology is derived accordingly based on the architecture to achieve the constant output current and unity power factor with significant energy storage reduction of the 100-/120-Hz energy buffer. Through a split and shared inductor, the required magnetic energy storage in the derived topology is the same as the conventional single-stage power factor correction converter, indicating high power density. Experimental evaluation verifies the performance in terms of improved power quality and conversion efficiency.

Experimental Verification of Single-Stage Power Factor Correction Converter with Improved Light-Load Efficiency

Single-stage single-switch ac/dc converters with power factor correction will have higher power losses under a light-load condition, as compared to that of two-stage approach, due to sharing of a common power transistor such that the power factor correction (PFC) stage cannot be switched OFF separately to save power losses. This paper addresses the problem by using a buck topology for the PFC stage of single-stage single-switch converters as it can completely turned OFF. This converter topology is capable of working in both buck mode and buck-boost mode depending on the rectified voltage at input side and power at load side. A simple and effective topology incorporating PFC for low power applications is simulated in Matlab/Simulink environment. Hardware implementation of the converter was and performance was verified with various practical light loads. It also satisfies the harmonic compliance of source current in accordance to the IEEE519:1992 recommendations. The control is very simple and gives good performance.

Boost-Type Single-Stage Step-Down Resonant Power Factor Correction Converter

Conventional boost power factor correction (PFC) converter is only suitable for two-stage power conversion system due to its high output voltage. Inherent step-up characteristic limits its applications in single-stage low voltage output. In this article, a boost-type single-stage step-down resonant PFC converter, which combines a boost PFC converter and a resonant switched capacitor network by using one active switch, is proposed and analyzed. Similar to conventional boost PFC converter, the proposed converter can achieve unity power factor and low input current ripple in universal-input applications. Moreover, the proposed converter can achieve step-down voltage conversion. Furthermore, high-efficiency is realized due to single-stage power conversion. The proposed converter is studied in terms of operation principle, voltage gain, power factor analysis, and key circuit parameters design. Finally, a 70-W prototype with 96.05% peak efficiency is built to verify the theoretical analysis results.

An Isolated PFC Zeta-forward Single-stage Single-switch for LED Driver Without Electrolytic Capacitor

The high-brightness light-emitting diodes (LEDs) require an AC/DC converter with power factor correction (PFC). The large output electrolytic capacitor, which is used to minimize the low frequency LED current ripple, degrades the operating lifetime of the LED driver. In order to increase the lifetime of an AC–DC LED driver, the electrolytic capacitor should be eliminated without significantly increasing the output current ripple. In this article, an isolated single-stage single-switch AC/DC high power factor LED driver without electrolytic capacitor is proposed in which a zeta power factor (PF) corrector is integrated with a forward converter. The detailed theoretical analysis and design procedure of the proposed single-stage PFC converter is presented. The experimental results of a 110 Vrms, 21 W prototype verify the theoretical analysis. The input PF is 0.99 in the proposed converter that complies with lighting equipment standards such as IEC-1000-3-2 for class C equipment.

Emulation of Loss Free Resistor for Single-Stage Three-Phase PFC Converter in Electric Vehicle Charging Application

In this article, the modular three-phase ac-dc converter using single-phase isolated Ćuk rectifier modules for charging of electric vehicles is discussed. The converters are designed and analyzed for the continuous conduction mode (CCM). This article is based on a new concept of adaptive sliding-mode-based loss-free resistor (ASLFR). ASLFR is a control scheme, which allows dual aim of power factor correction along with tight voltage regulation; hence, the adopted topology serves as a fitting single-stage solution for balanced three-phase systems. Complete theory is developed for the application, and the effectiveness of the scheme is well-established. Various studies to confirm the robustness of the system to any load and line variation are carried out. Moreover, a qualitative analysis is also made to show the expediency of the proposed ASLFR. Simulation as well as experimental studies are claimed theoretically.

Adaptive on Time Controlled Double-Line- Frequency Ripple Suppressor With Fast Dynamic Response and High Efficiency

Due to the input power and output power do not match in real time, single-stage power factor correction converters have large double-line-frequency ripple at the output voltage. The double-line-frequency ripple voltage will cause some electronic devices to work abnormally, and limit the control loop bandwidth of power factor correction converter. In order to reduce the output double-line-frequency ripple voltage, a single-stage Flyback power factor correction converter with Buck ripple suppressor is used in this paper, the Buck ripple suppressor can generate same magnitude but 180° phase shifted voltage as Flyback power factor correction converter output voltage ripple. Adaptive on-time control is adopted in the Buck ripple suppressor benefiting with its wider bandwidth and fast dynamic response. The switching frequency range and stability of Buck ripple suppressor under constant on-time control and adaptive on-time control are discussed. By establishing the input-output audio susceptibility model, the output double-line-frequency ripple suppression performance is analyzed. Buck ripple suppressor using adaptive on-time control can suppress double-line-frequency ripple voltage effectively with the fast dynamic response and high efficiency. Simulation and experimental results are given to verify the theoretical analysis.

Feed‐forward control scheme to improve light‐load power factor for single‐stage flyback PFC converters

In this Letter, the author proposes a new feed-forward controller for single-stage flyback power factor correction (PFC) converters. By compensating the phase-lead effect caused by input capacitor current, the proposed feed-forward control duty improves the displacement factor as well as the distortion factor, and so the flyback PFC converter has high power quality. By means of the synchronous rectification circuit, the flyback PFC converter can operate in reverse when the negative current is required. To confirm the theoretical analysis and validity of the proposed control scheme, the author demonstrated the proposed control algorithm with 80 W flyback PFC converter prototype.

A duty cycle generation scheme for the three‐phase single‐stage full‐bridge PFC in balanced‐grid

In this Letter, the duty cycle generation scheme is presented and implemented, which can improve the input performances of the three-phase single-stage full-bridge power factor correction (PFC) converter. The analysis and discussion is aiming at the operation of the PFC converter in balanced grid condition. On the basis of the instantaneous expression of the three-phase input current, the ideal duty cycle of each phase is obtained. To achieve a good PF for each phase, a simplified duty cycle generation scheme is presented and implemented in the three-phase PFC converter. The simulating and experimental results based on a 500 W prototype show that after adoption of the presented duty cycle generation scheme, a higher PF has been achieved for each phase of the three-phase PFC converter.

Z-Source Resonant Converter With Power Factor Correction for Wireless Power Transfer Applications

In this paper, the Z-source converter is introduced to power factor correction (PFC) applications. The concept is demonstrated through a wireless power transfer (WPT) system for electric vehicle battery charging, namely Z-source resonant converter (ZSRC). Due to the Z-source network (ZSN), the ZSRC inherently performs PFC and regulate the system output voltage simultaneously, without adding extra semiconductor devices and control circuitry to the conventional WPT system such as conventional PFC converters do. In other words, the ZSN can be categorized as a family of the single-stage PFC converters. In addition, the ZSN is suitable for high-power applications since it is immune to shoot-through states, which increases reliability and adds a boost feature to the system. The ZSRC-based WPT system operating principle is described and analyzed in this paper. Simulations and experimental results based on a 1-kW prototype with 20-cm air gap between the system primary and secondary sides are presented to validate the analysis and demonstrate the effectiveness of the ZSN in the PFC of the WPT system.

Single-Stage Boost-Buck PFC Converter with Soft-Switching Operation and Ripple-Free Output Current

In this paper, a single-stage boost-buck power-factor-correction (PFC) converter with soft-switching operation and ripple-free output current is proposed. In order to obtain high power factor, a boost PFC cell is operated in discontinuous conduction mode (DCM) with a fixed switching frequency according to the load condition. For the ripple-free output current, a buck inductor is replaced with a coupled inductor and an auxiliary capacitor. The boost PFC cell and the buck converter share a main switch and a self-driven synchronous rectifier (SR). By turning the SR off after a short delay, the main switch is turned on under zero-voltage-switching (ZVS) condition. Since the conduction loss on the SR is reduced and there is no switching loss on the main switch, the power-conversion efficiency is improved. The maximum efficiency of the proposed converter 93.37% is measured at 130vac. To verify the performance of the proposed converter, theoretical analyses, design procedures, and experimental results from a 80V and 100W prototype are presented.

Study on the Single-Stage Forward-Flyback PFC Converter With QR Control

The single-stage forward-flyback power factor correction converter with quasi-resonant (QR) control is studied in this paper. This converter merges flyback converter and forward converter through a common transformer. Only the flyback subconverter works when the input voltage is lower than the reflected output voltage while both the flyback subconverter and the forward subconverter operate to share the output power in the rest region. The dead zones which exist in the ac input current of traditional forward converter are eliminated and high power factor can be achieved. Two different QR control schemes have been studied. Detailed analysis, optimal design considerations, and comparison for these two QR control modes are provided. Finally, two 120 W experimental prototypes for LED driver were built up to verify the theoretical analysis.

English

English

English

The PMBLDCM is used to drive a compressor load of an air conditioner through a three-phase VSI fed from a controlled DC link voltage. A buck half-bridge DC-DC converter is used as a single-stage Power Factor Correction (PFC) converter for feeding a Voltage Source Inverter (VSI) based Permanent Magnet Brushless DC Motor (PMBLDCM) drive. The front end of this PFC converter is a Diode Bridge Rectifier (DBR) fed from single-phase AC mains. The speed of the compressor is controlled to achieve energy conservation using a concept of the voltage control at DC link proportional to the desired speed of the PMBLDCM. Therefore the VSI is operated only as an electronic commutator of the PMBLDCM. The stator current of the PMBLDCM during step change of reference speed is controlled by a rate limiter for the reference voltage at DC link. The proposed PMBLDCM drive with voltage control based PFC converter is designed, modeled and its performance is simulated in Mat lab- Simulink environment for an air conditioner compressor driven through a 1.5 kW, 1500 rpm PMBLDC motor. The evaluation results of the proposed speed control scheme are presented to demonstrate an improved efficiency of the proposed drive system with PFC feature in wide range of the speed and an input AC voltage.

A Fully Integrated Three-Level Isolated Single-Stage PFC Converter

For low-cost isolated ac/dc power converters adopting high-voltage dc-link, research efforts focus on single-stage multilevel topologies. This paper proposes a new single-stage three-level isolated ac/dc PFC converter for high dc-link voltage low-power applications, achieved through an effective integration of ac/dc and dc/dc stages, where all of the switches are shared between two operations. With the proposed converter and switching scheme, input current shaping and output voltage regulation can be achieved simultaneously without introducing additional switches or switching actions. In addition, the middle two switches are turned on under zero current in discontinuous conduction mode operation, and the upper and bottom switches are turned on under zero voltage. Due to the flexible dc-link voltage structure, high power factor can be achieved at high line voltage. A 500 W/48 V prototype is designed to serve as the proof of concept, which exhibits 90.8% peak efficiency at low input line voltage.

Dead Angle Reduction of Single-Stage PFC Using Controllable Coupled Inductors

This paper presents a new structure of single-stage flyback power factor correction (PFC) converter with a controllable coupled negative magnetic feedback (NMF) winding. NMF winding is used to reduce the bulk capacitor voltage at high line voltages and light loads. However, it would cause line current distortion at zero crossing condition. In the proposed circuit, a series winding is used with NMF inductor to eliminate the NMF inductor at low line voltages. As a result, the dead angle of the input current, near zero voltage crossing, is eliminated and the power factor is increased. The presented experimental results of the proposed PFC converter confirm the integrity of the new idea and the theoretical analysis.