Input Power Factor Correction Research Articles

A non-inverting single-switch buck-boost converter based LED driver

<span lang="EN-US">This paper focuses on a single-switch buck-boost (SSBB) converter for light emitting diode (LED) lighting applications. The proposed LED driver with power factor correction (PFC) shows enhanced performance in terms of input power factor, efficiency and reduced voltage stress across the switch. The presented LED driver is operated in discontinuous conduction mode (DCM). The input PFC is carried out using average current mode control (ACMC) and the controller is optimized using artificial bee colony (ABC) algorithm. A hardware prototype of 50W LED driver with ACMC for PFC is implemented using a programmable interface circuit (PIC) microcontroller. The experimental results are presented and the performance is compared with a conventional buck boost LED driver. The proposed SSBB LED driver achieves an input power factor of 0.96 with an efficiency of 98%.</span>

Family of single‐phase high‐frequency isolated AC–AC converters

AbstractThis work presents a family of single‐phase ac–ac converters with high‐frequency isolation based on the association of interleaved transformers and the dual active bridge (DAB) converter. From distinct configurations of the dc link in terms of half‐bridge (HB), full‐bridge (FB), and interleaved full‐bridge (IFB) arrangements, one can obtain three symmetrical and six asymmetrical structures, with distinct trade‐offs among the number of active switches, total dc‐link voltage, and effective operating frequency of the filter elements. Prominent advantages of the derived circuits include input power factor correction (PFC), a nearly sinusoidal load voltage, the operation of active switches under soft‐switching condition during part of the line period, reduced current stresses, good current sharing due to the interleaved transformers, as well as multilevel voltage waveforms on both sides of the high‐frequency transformer (HFT). Experimental results obtained from an experimental prototype of an ac–ac FB‐IFB converter are presented to validate the theoretical assumptions.

FPGA Implementation of Fixed-Point Model for a Single-Phase AC-DC Converter with Unity Power Factor

This paper presents a design of digital control based on a fixed-point model for an application of a single phase AC-DC boost Converter with a high power factor and low current distortion. The system uses a simple closed-loop control with a slow voltage loop (outer loop) to stabilize the output DC bus voltage at the required level and a fast current loop (inner loop) to achieve input power factor correction. The digital control uses a fixed-point structure that improves the control accuracy without increasing the number of arithmetic operations and does not require specific running conditions. The behavior of the system is fully verified by using a digital simulation under Matlab/Simulink environment and experimentally with an implementation in real-time using Xilinx ISE 14.7 software, hardware description language VHDL, Xilinx FPGA ML605 board, and EVAL-AD7656 evaluation board for high-speed analog-to-digital conversion. The obtained results show a good agreement between experiments and simulations for steady-state and transient-responses.

Single-Phase Isolated AC–AC Symmetrical Full-Bridge Converter

This work proposes an ac–ac converter based on interleaved transformers associated with the dual active bridge (DAB) converter. The resulting symmetrical full-bridge converter (SFBC) can achieve high efficiency over a wide range of the output power and bidirectional power flow, as well as high power density owing to the possible integration of magnetics. The voltage waveforms on the high-frequency transformer (HFT) present five levels, resulting in filter elements with reduced dimensions. A detailed mathematical analysis of the SFBC comprising the operating stages, modulation technique, and soft-switching range is derived. An experimental prototype rated at 1 kW is implemented to validate the theoretical assumptions, thus demonstrating that the SFBC is capable of providing input power factor correction (PFC) and a load voltage waveform with low harmonic content.

Design, implementation and experimental testing of a hybrid power supply of remote measuring station in the Surveillance, Alert & Warning System (SAWS)

The paper presents the design, implementation and experimental testing of a hybrid power supply of telecommunication and measuring equipment incorporated in remote measuring stations, which are an integral part of the global Surveillance, Alert & Warning System (SAWS) in the Republic of Serbia. In these systems, it is very important to provide autonomy of permanent, reliable and quality power supply. In this case, the power supply system is in effect based on the use of solar energy i.e., photovoltaic (PV), in combination with the mains power supply 230V, 50Hz. Solar power is the primary source of power during the day, while in night conditions the secondary power supply is a distribution power grid (more precisely, the distribution power which is used for supplying the night street lighting). This hybrid power system is realized with two controlled chargers (MPPT solar and mains with input power factor correction), battery bank 12V/110Ah with the corresponding system for its monitoring and secondary DC/DC power converters for supplying telecommunication and measuring electronic modules. The key implementation and experimental results obtained during the realization of a SAWS remote measuring station on the river Ub (municipality of Ub), will be presented in the paper.

GaN-Based High-Power-Density AC–DC–AC Converter for Single-Phase Transformerless Online Uninterruptible Power Supply

This article introduces a new transformerless ac-dc-ac converter topology suitable for a high-power-density high-frequency single-phase online uninterruptible power supply (UPS) with a common neutral between the input and output ac ports. The proposed converter comprises an input power factor correction rectification (ac-dc) stage which is followed by an inversion (dc-ac) stage. The rectification stage operates in boost mode during the input positive half line cycle and buck-boost mode during the input negative half line cycle, while the inversion stage operates in buck and buck-boost modes in the output positive and negative half line cycles, respectively. The rectification stage utilizes boundary conduction mode control enabling soft-switching and allowing high-frequency operation. The inversion stage is operated in continuous conduction mode, wherein a digital controller regulates the output voltage of the converter across both resistive and reactive loads. The proposed online UPS utilizes a single (nonsplit) dc-bus between the rectification and inversion stages, resulting in a 50% reduction in dc-bus capacitance requirement compared to conventional split-bus online UPS topologies. Additionally, two battery interface solutions are also investigated which provide a trade-off between passive volume and additional switch-count. To verify the performance and control of the proposed online UPS, a GaN-based electrolytic-free 1-kVA prototype online UPS is designed, built, and tested. The prototype ac-dc-ac converter achieves a peak efficiency of 95.2% and maintains a high efficiency of above 92.3% across the full output power range. The electrolytic-free prototype ac-dc-ac converter for the online UPS achieves a power density of 26.4 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .

Single‐stage pulse frequency controlled AC–AC resonant converter for different material vessel induction cooking applications

SummaryThis paper presents a single‐stage AC–AC resonant converter configuration for different material vessel induction cooking. The proposed configuration features input power factor correction, boost operation, and integrated bridge inverter configuration for multiple loads. In this topology the inverter legs are operated at two different frequencies to power induction cooking loads of steel and aluminum vessels. The induction cooking loads are operated at frequencies closer to their respective resonant frequencies. The load powers are independently controlled by pulse frequency modulation (PFM) technique. The proposed topology eliminates the use of electromechanical switches. The proposed single‐stage AC–AC resonant converter configuration has been tested with two different vessels of steel and aluminum. The simulation and experimental results of the proposed configuration are in good agreement. This topology offers the advantages of low component count, high efficiency, and suitability for different material induction cooking.

Non‐isolated high step‐up/step‐down quadratic converter for light‐emitting diode driving

SummaryThis work presents an alternating current–direct current (AC–DC) single‐switch quadratic single‐ended primary inductance converter (SEPIC) for applications involving light‐emitting diodes (LEDs). The proposed topology is basically composed of two cascaded SEPIC stages, where the first one provides input power factor correction (PFC) and the second one allows obtaining power control (PC) for dimming purposes. It is also capable of providing high step‐up or step‐down without requiring the use of extreme duty ratios. A detailed qualitative analysis is derived, from which it is possible to obtain a consistent design procedure. Experimental results from a laboratory prototype are thoroughly discussed aiming at validating the theoretical assumptions.

High Power Density Laboratory Prototype of Single-Phase Solid-State Transformer

Ever since the rise in infiltration of renewable sources into the modern electric grids, the concept of solid-state transformer (SST) has garnered special attention to dynamically control and regulate the power flow while preserving the quality of supply. Though SSTs are capable of catering to a myriad of service demands by customers, their complex multistage architecture, large device count, complexity in control, increased device losses and relatively higher cost remain major bottlenecks for their widespread market penetration. This paper is intended to address the major impediments mentioned above by proposing a simple three-stage, modular architecture for SST with a minimal switch count, high power density and input power factor correction for low power applications. Each stage of SST is equipped with independent, simple and robust controllers contributing to high degree of modularity. A 1 kVA laboratory prototype is built for supplying power to sensitive electric equipment and the results presented in support of the proposed architecture. The developed prototype is shown to have unity power factor at the input, less than 10 percent of the weight and more than thrice the power density relative to the conventional transformer of similar rating.

Analysis of Converters for Single Phase LED Driver with Input Power Factor Correction

Most of the loads in household are inductive in nature and hence have low power factor. When, the power factor is low the current flowing through the system components will be higher. It results in heating and shortens the life of the system. Hence, power factor improvement is necessary. This paper proposes the comparison of bridgeless Single-ended primary-inductance converter (SEPIC) and bridgeless Landsman converter with the input power factor correction for LED drive application. The gating signal for switches in the converters are generated using PWM generator. Bridgeless configuration is used to reduce the conduction loss in the negative half cycle which improves the efficiency of about 1 to 2% for the entire power supply. In this configuration number of conducting diodes is reduced. This proposed work is designed and simulated using MATLAB / Simulink software. The simulated results from the two converters were analyzed for the input power factor correction.

Efficient two-stage offline driver for extra-high-current COB LED applications

This work proposes a reliable and efficient two-stage driver solution for extra-high-current (EHC) chip-on-board (COB) light-emitting diode (LED) applications. An ac–dc boost converter operating in continuous conduction mode is employed to provide input power factor correction and regulated dc-link voltage. Considering that EHC COB LEDs often operate at higher current levels than those employed in conventional high-powered lighting applications, a dc–dc extended gain interleaved buck converter (EGIBC) is employed so that power control is achieved. The average state-space modeling of the EGIBC is derived, while a digital control system is also implemented for this purpose. A 500-W prototype of the proposed two-stage topology is implemented, which does not require electrolytic capacitors. The obtained results clearly demonstrate that the proposed driver complies with international power quality and flicker standards. Thus, it can be consolidated as a viable choice for practical applications involving outdoor floodlighting where high luminous flux is mandatory.

An Integrated Electrified Powertrain Topology With SRG and SRM for Plug-In Hybrid Electrical Vehicle

With the advantages of less carbon dioxide emissions and high fuel efficiency, plug-in hybrid electrical vehicle (PHEV) is an attractive means of transportation. This article presents an electrified powertrain for PHEV containing switched reluctance generator (SRG), switched reluctance motor (SRM), and integrated power converters, which could achieve various driving and flexible on-board charging functions. The operation states of SRG and SRM with the integrated topology is analyzed. Five driving modes for PHEV are implemented and can be smoothly switched by controlling the front-end converter according to the load conditions. For the PHEV charging mode, a single-phase ac–dc rectifier is constituted by the windings and power converter of SRG with the capability of input power factor correction. The traction and auxiliary batteries chargers are formed by the windings and power converter of SRM. Three charging modes also are achieved and no complex control strategies are required to avoid the rotation of rotors. The three-phase 12/8 poles SRG and SRM experimental platform are built. The experiments are carried out to verify the effectiveness of proposed integrated powertrain and the corresponding control schemes.

Design and development of single phase AC–DC discontinuous conduction mode modified bridgeless positive output Luo converter for power quality improvement

Power factor corrected AC–DC converter topologies have been of research interest for DC power supplies. The main goal of this work is to improve power quality at the supply side and maintain constant DC voltage at the output side by designing a Modified Bridge Less Positive Output Luo (MBLPOL) power factor correction (PFC) converter. Discontinuous conduction mode is also possible for input PFC with a small filter at the source side. In order to regulate the DC load voltage for various loads and supply voltage conditions, a feedback control circuit with a single voltage sensor is proposed for the PFC converter. A prototype of 100 W, 48 V, AC–DC MBLPOL converter is designed and tested. Proper design of controller for the converter guarantees the excellent performance and the same is validated with the help of simulation and hardware results. The proposed MBLPOL converter is tested for DC load voltage regulation for various load power and supply voltage variations. The experimental study shows supply current total harmonic distortion of 1.24% at rated load while maintaining unity power factor.

Power Factor Correction of Three-Phase PWM AC Chopper Fed Induction Motor Drive System Using HBCC Technique

In this paper, a new control strategy for an induction motor (IM) drive system fed from three-phase pulse width modulation (PWM) ac chopper is proposed. The main objective of the proposed control scheme is to achieve input power factor correction (PFC) of the IM drive system under different operating conditions. PFC is achieved by continuously forcing the actual three-phase supply currents with the corresponding reference currents, which are generated in phase with the supply voltages, using hysteresis band current control (HBCC) technique. The proposed control strategy has two loops: the inner loop and outer loop. The output of the outer loop is the magnitude of the supply reference current resulting from either speed controller or startup controller, whereas the output of the inner loop is PWM signals of the ac chopper. The proposed ac chopper features a smaller number of active semiconductor switches, four IGBTs, with only two PWM gate signals. As a result, the proposed system is simple, reliable, highly efficient, and cost effective. Mathematical analysis of the drive system is presented. Components of the input LC filter are designed using frequency response. The IM drive system is modeled using MATLAB/SIMULINK, and a laboratory prototype was built and tested. The simulation and experimental results confirm the validity and robustness of the proposed control strategy.

Speed-Sensorless DTC of a Matrix Converter Fed Induction Motor Using an Adaptive Flux Observer

ABSTRACT This paper aims at combining some of the best features of an available induction motor (IM) drive system while introducing a simplified adaptive flux estimation algorithm for sensorless operation. The use of a matrix converter (MC) is proposed to achieve improved source side power quality and input power factor correction of an IM drive. Direct torque control (DTC) of an IM is realized through appropriate switching of the MC and the control strategy is implemented with speed-sensorless operation by using a relatively simplified adaptive flux observer. DTC through speed and flux estimation is realized in the stationary reference frame. Primarily, three objectives are achieved, viz. speed regulation while directly controlling the motor torque (and flux), improved source side power quality owing to the use of MC, and substantially simplified sensorless estimation strategy. Additionally, economic benefits are also achieved owing to negligible energy storage requirements of the drive and sensorless operation.

Single-Phase LED Drivers With Minimal Power Processing, Constant Output Current, Input Power Factor Correction, and Without Electrolytic Capacitor

High-power light-emitting diodes (LEDs) having properties of high luminous efficacy and long life span are becoming a major light source for general illumination. To fully utilize the advantages of LED in lighting applications, the offline power supply that drives the LED should possess the following features: high efficiency, long life span, high input power factor, and (COC). In this paper, high efficiency is achieved by using a minimal power processing (MPP) configuration. Near perfect power factor correction (PFC) is achieved by a simple dual-output disc-ontinuous-conduction-mode (DCM) pulse-width-modulated (PWM) front-end converter. One output of the front-end converter is connected to the LED load using a control switch. The other output is connected directly to a dc storage capacitor cascaded with a downstream DCM PWM converter driving the same LED load to achieve COC driving. The power flow is controlled to achieve the required MPP that can also reduce the storage capacitance by balancing only the ac input ripple power and the dc output power without power recycling. Thus, the design requires no electrolytic capacitor, hence extending the system life span. The achievement of input PFC, MPP, and COC requires design tradeoff among design freedom, ease of control and component count. LED drivers having all these properties are developed, designed, and tested.

A Commercial Low Cost, Highly Efficient UC3842 based High Brightness LED (HBLED) Lamp

The conventional lighting sources like incandescent and fluorescent lamps are replaced by High Brightness Light Emitting Diodes (HB-LEDs). In this paper, a HBLED driver using a Single Ended Primary Inductor Converter (SEPIC) with input Power Factor Correction (PFC) is presented. PFC is accomplished using a commercial inexpensive Peak Current Mode Controller (PCMC) IC UC3842 is newly combined with SEPIC converter. Extensive simulation results are carried out and a laboratory prototype to power 18W LED array from AC mains is implemented and the results are presented in detail.

A High-Frequency Isolated Online Uninterruptible Power Supply (UPS) System with Small Battery Bank for Low Power Applications

Uninterruptible power supplies (UPSs) are widely used to deliver reliable and high quality power to critical loads under all grid conditions. This paper proposes a high-frequency isolated online UPS system for low power applications. The proposed UPS consists of a single-stage AC-DC converter, boost DC-DC converter, and an inverter. The single-stage AC-DC converter provides galvanic isolation, input power factor correction, and continuous conduction of both input and output current. The low battery bank voltage is stepped up to high dc-link voltage by employing a high voltage gain boost converter, thus allows the reduction of battery bank to only 24 V parallel connected batteries. Operating batteries in parallel improves the battery performance and resolves the issues related to conventional battery banks that arrange the batteries in series combination. The inverter provides regulated output voltage to the load. A new cascaded slide mode (SM) and proportional-resonant (PR) control for the inverter has been proposed, which regulates the output voltage for both linear and non-linear loads. The controller shows excellent performance during load transients and step changes. Besides, the controller for boost converter and AC-DC converter is presented. Operating principle and experimental results of 1 kVA laboratory setup have been presented for the validation of proposed system.

Analysis and Design of a Series–Parallel Uninterruptible Power Supply with an Improved Control Strategy for Seamless Transition

In this paper, a high-performance control structure is designed, implemented, and applied to a three-phase series–parallel uninterruptible power supply (UPS). This kind of UPS system provides input power factor correction, output voltage conditioning, and high efficiency. The control strategy proposed in this paper is based on voltage control of the parallel converter and current control of the series converter. It is shown that this strategy improves the system operation, specifically resulting in a smoother and more seamless transition between UPS operating modes. The controller in the proposed strategy is based on combination of two control methods with different characteristics and is therefore called a hybrid structure. To enhance the steady-state performance of the UPS and reach fast error convergence, a repetitive controller is used. In addition, to reach a fast transient response required for control of output voltage, a fast deadbeat is used. The stability of this hybrid controller is discussed, and the design procedure for a typical converter is given. For validation and verification of the theoretical analysis, both experimental and simulation results are shown.

A Double-Loop Primary-Side Control Structure for HB-LED Power Regulation

This paper presents a study of high-brightness LED (HB-LED) strings under power drive control, in which the LED's input power is controlled rather than its current. In the conventional constant current drive technique, any changes in the LED string's forward voltage results in output light variations due to a strong dependence between the LED output light to its input power. Under constant power drive control, the LED string's forward voltage variations due to ambient temperature changes and aging are compensated. To evaluate the power drive control method, an inner–outer-loop control structure is developed by utilizing an ac–dc flyback converter. To this end, a primary-side LED power estimator and controller are proposed to achieve simultaneous output power regulation and input power factor correction. An expression is obtained for the LED power in terms of its input current and ambient temperature that can provide qualitative and quantitative behavior in constant-current and constant-power drive regimes. Experimental results using a Cree CR22-32L LED string are presented and compared with the constant current drive technique for temperature variations in the range 25–80 $^\circ$ C. For the aforementioned temperature range and using similar hardware, the proposed controller results in an 8% reduction of the LED output light when compared to a 13% reduction using the constant current drive technique.