High Input Power Factor Research Articles

Design and Development of an Efficient, High Power Factor, Low-Cost, RGB LED System for Tuneable Lighting Application

Branded smart red (R) – green (G) – blue (B) light emitting diode (LED) products commercially available in developing countries are too costly to afford for most of the population, especially for household applications. Locally manufactured cheaper alternatives of such products suffer from poor power factor and reduced circuit efficiency. To address these technical issues, a smart RGB LED system is presented here which offers high input power factor, good circuit efficiency, and at the same time lower fabrication cost and user-friendly control interface. The unique features of the proposed system are the front-end AC/DC converter is a constant-voltage, multiple-output flyback converter that mitigates the need of multiple drivers and inductors. The second is that the same converter is operated in discontinuous conduction mode to achieve a high input power factor. The third is that for dimming and colour tuning, pulse width modulation (PWM) control of the MOSFET switches is accomplished by an Arduino Mega 2560 microcontroller instead of other costlier and more sophisticated options. And the fourth is that the microcontroller gets its command signal from a smartphone or computer through an HC‑05 Bluetooth module. Through laboratory testing, it is confirmed that the LED system offers close-to-unity input power factor (0.928–0.985) and high efficiency of (88.14–95.46) % for a wide range of colour and luminous intensity. A comparative study reveals that the developed system is a better option than the earlier reported prototypes of multicolour LED systems in terms of the bill of material, economy, power factor, and efficiency.

A Novel Unidirectional Three-Phase Multilevel Rectifier Composed of Star-Connected Three Single-Phase Topology Based on Five-Level Flying Capacitor DC–DC Converter

A novel unidirectional three-phase multilevel rectifier composed of star-connected three single-phase topology based on five-level flying capacitor DC-DC converter is proposed, which can be widely applied to many industrial applications, especially for the front-end of multilevel converters for AC adjustable motor drives with open-end winding connection. In addition to not requiring transformers (either line-frequency or high-frequency), compared to other high voltage rectifiers, this proposed topology features fewer active switches with lower voltage stress, a high voltage common DC bus, high input power factor and low input current harmonics. In this paper, a comprehensive analysis to the basic operating principles including the topology configuration, the steady-state modeling and phase-shifted SPWM modulation are presented. A hybrid control strategy is studied, including the input power factor control, the dc-link voltage balancing control and the flying capacitor voltage balancing control with balanced and unbalanced loads. Finally, the experimental results are presented to validate the feasibility and correctness of the proposed solution.

The current status and development of DC/AC inverter technology

The advantages, applications, and development trends of DC/AC inverter technology are compared with conventional inverter technology. The traditional DC/AC inverter technology of the low-frequency link inverter process has been gradually replaced by the high-frequency band inverter process. The replacement of the industrial frequency transformer in the low-frequency link inverter process technology with a high-frequency transformer further optimizes and improves the low-frequency link inverter process technology and significantly enhances the characteristics of the inverter. In this paper, some new inverters are highlighted. The focus is on a new high-frequency chain inverter using a unipolar SPWM control method to design different drive logic control switch tubes. A single-stage single-phase high-to-low voltage converter is widely used to interchange solar and wind turbine power supplies. They all belong to PV inverters with high reliability and a wide input voltage range. These completely solve the problems of large size, high ratio, and poor dynamic response of low-frequency transformers. Future trends in inverters at this stage are mainly characterized by high frequency, high performance, and high input power factor.

An Integrated Single-Stage Single-Switch Topology With Reduced Nonlinear Components for LED

This article presents an integrated single-stage single-switch (4S) ac–dc system for LED delivering a high input power factor (IPF) and regulated output. The proposed topology integrates a power factor correction (PFC) converter with a high-frequency dc–dc converter, driven by a modified front-end single-phase Vienna rectifier. The integration results in a single switch prototype, thus decreasing the cost and complexity of the control circuit. The use of fewer diodes in the front-end rectifier reduces the nonlinearity in the proposed topology. First-stage filter capacitors offer a better input dynamics to the PFC stage. The proposed (4S) prototype offers less component counts and minimal input current harmonics. The theoretical and mathematical analysis of the proposed topology is presented. Finally, the proposed (4S) ac–dc system analysis and simulation results have been verified with a 50 W/60 V prototype depicting an IPF of 0.997, total harmonic distortion (THD) of 3.96%, and an efficiency of 90.8%. The presented experimental results coincided with the analysis and comply with IEC61000-3-2 standards.

A Proprietary ZVS-Based Approach Delivers High Efficiencies at Light Load With Half the Components of Conventional Designs

The ac–dc power supply units providing isolated, regulated outputs operating above 100 W typically require some form of input active power factor correction (PFC) <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> . To achieve this, a popular solution is to combine a boost PFC input stage with an “LLC” converter which isolates and controls the dc output voltage. However, a new, innovative single-stage technique for delivering regulated ac–dc power with a high input power factor offers the promise of high efficiency from no-load to full-load, while halving the number of active devices (MOSFETs) when compared to the traditional approach.

Three Port Isolated AC/DC Converter with Power Factor Correction

1: : This paper proposes a converter with three ports with isolated output and higher output power and voltage levels. The converter has two input ports, connecting an AC source and the solar PV source. The third port acts as an output port to supply the desired load. The proposed topology can supply the high dc output voltage with isolation while maintaining a high input power factor. A single-stage conversion is used, which helps in reducing the switching devices and the bulky electrolytic capacitor while integrating a Solar PV. As there is no intermediate stage of conversion in the proposed converter, thus it is well suited for the standalone PV based application such as remote light electric vehicle chargers. The simulation verification of the proposed converter is obtained in the MATLAB/SIMULINK and the experimental results are obtained using control algorithm implemented using FPGA based Typhoon HIL 402. Background: To implement the proposed novel converter and study the switching operations Objective: Conventionally, a two-stage conversion is required for providing isolated DC output Methods: Verification of control method in simulation with hardware validation Results: Justified the control method and working of topology Conclusion: The desired operation of the converter is achieved

A High-Efficiency Isolated PFC AC–DC Topology With Reduced Number of Semiconductor Devices

A new three-level isolated ac–dc power factor correction (PFC) topology with a minimum number of semiconductor devices is the focus of this article. This topology provides a high input power factor (PF), soft-switching, and higher efficiency than existing isolated ac–dc converters. Furthermore, the proposed circuit has lower voltage rating requirements for the secondary side devices, which leads to a lower total cost and minimizes total converter losses. This article presents a theoretical analysis describing the complete characterization of this new topology, and experimental results on a 1-kW prototype showing high PF and efficiency throughout the operating range.

Analysis and Output Power Control of Unidirectional Secondary-Resonant Single-Active-Half-Bridge DC-DC Converter

Development of high-frequency-isolated DC-DC converters is underway for charging and discharging electric vehicle batteries. As a charger, a Single Active Bridge (SAB) converter, which is composed of a primary full-bridge converter, a high-frequency transformer, and a secondary full-bridge diode rectifier circuit, has been proposed as a unidirectional high frequency isolated DC-DC converter. In this paper, as a simple circuit configuration, a Secondary-Resonant Single-Active-Half-Bridge (SR-SAHB) converter, in which the primary and secondary circuits of the SAB converter are both half-bridge circuits, and a resonant capacitor connected in parallel to each secondary diode, is created. Due to the partial resonance on the secondary side, power transmission with unity transformer turn ratio and unity voltage conversion ratio can be realized, and a high total input power factor of the transformer can be achieved. As a result, the maximum voltage and current of the switching devices and the transformer voltage can be reduced. Moreover, soft switching in all commutations can be realized. The operation waveform is analyzed, and output power control is derived using the variable frequency control method. The effectiveness of the proposed SR-SAHB has been verified by experimental results using a 2.4 kW 20 kHz, 265 V laboratory prototype.

Power Factor Corrected by Buck-Boost Converter type Battery Charger Employing PWM Technique with Capacitor Bank

In this paper, a buck-boost type battery charger is developed for charging battery set with a lower voltage. This battery charger is configured by a rectifier circuit, an integrated boost/buck power converter and a switched capacitors circuit. A boost power converter and a buck power converter sharing a common power electronic switch are integrated to form the integrated boost/buck power converter. By controlling the common power electronic switch, the battery charger performs a hybrid constant-current/constant-voltage charging method and gets a high input power factor. Accordingly, both the power circuit and the control circuit of the developed battery charger are simplified. The switched capacitors circuit is applied to be the output of the boost converter and the input of the buck converter. The switched capacitors circuit can change its voltage according to the utility voltage so as to reduce the step-up voltage gain of the boost converter when the utility voltage is small. Hence, the power efficiency of a buck-boost type battery charger can be improved. Moreover, the step-down voltage gain of the buck power converter is reduced to increase the controllable range of the duty ratio for the common power electronic switch. A prototype is developed and tested to verify the performance of the proposed battery charger

Soft Switching Control of Power Factor Correction for Distribution System

A boost Power Factor Correction (PFC) front end converter followed by a full bridge transformer-isolated dc/dc converter is popular in offline dc power supply. In this configuration switching losses are high and overall efficiency is reduced. For solving this problem individual soft-switching techniques are required for both the converters. A dc power supply system that uses a new Zero-Voltage Switching (ZVS) strategy to get ZVS function is proposed here. A soft-switching dc power supply system with high input power factor and stable dc output voltage is presented with simple and compact configuration. The proposed circuit is not only operated at constant frequency, but all semiconductor devices are operated at soft switching without additional voltage stress. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path, and the rectifier in the proposed converter uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. An average-current-mode control is employed in proposed dc power supply system to synthesize a suitable low-harmonics sinusoidal waveform for the input current.

CRM Buck converter with high input power factor

CRM Buck converter with high input power factor

Research on digital long-life time LED driver

LEDs enjoy lifetime up to 10 years, while the lifetime of LED drivers using electrolytic capacitor as power balance component is limited to typically less than 5 years. There is a relatively large deviation between the life of the LED and the life of the power supply. Therefore, it is necessary to eliminate electrolytic capacitors from LED drivers. In this study, a novel digital LED driver without electrolytic capacitor is designed for the problem of the electrolytic capacitors in LED driver is proposed. Compared with traditional LED drivers, the designed driver in this paper not only has the advantage of high input power factor and constant output current, but also because all control functions are realized using software, which provides great flexibility for system modification. The working principle is presented in the article. Finally, the feasibility of the proposed LED driver has been successfully proved by experiment.

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.

Single-Phase to Three-Phase Electrolytic Capacitor-Less Dual Inverter-Fed IPMSM for Suppress Torque Pulsation

An electrolytic capacitor-less single-phase to three-phase power converter controls the motor and the input power factor. However, the motor power and the torque are pulsated because the input power of the inverter is irregular. This article proposes a power converter and control method to realize a high input power factor and constant motor torque using a dual inverter without an electrolytic capacitor and an open-end winding machine. The proposed system has the following features. First, the proposed control method achieves a high input power factor by controlling the single-phase ac power without affecting the motor current. Second, the proposed control method compensates the pulsation the of load voltage by using an additional inverter. The proposed circuit configuration and control method contributes to the small size and weight, and high efficiency of the motor drive system with a single-phase power supply. The effectiveness of the proposed system is verified through experiments. The proposed system suppresses torque pulsation by 95.5% compared to the conventional system, and the input power factor is 97.2% at 1.5 Nm and 2500 r/min load condition.

A Torque Control Method Based on I-MR Controller for IPMSM Drive With Small DC-Link Capacitor

In traditional motor drive system, large volume electrolytic capacitors are utilized to buffer energy and stabilize the dc-link voltage. However, these capacitors affect the reliability of the drives and narrow the conduction angle of diode-rectifier. As a result, the grid side current is distorted and the power factor is deteriorated. In order to settle these issues, small dc-link capacitors can replace the electrolytic capacitors. In this paper, a motor torque control method with dc-link voltage feed-forward compensation for an interior permanent magnet synchronous motor (IPMSM) drive system is proposed. Hence, an integration multi-resonant ( I-MR ) controller is established to regulate the motor torque to obtain high input power factor and low grid current harmonics. In addition, a voltage feed-forward compensation is used to diminish the error of motor torque control. The effectiveness of the proposed method is verified through simulation and experiments. Results indicate that the input power factor can reach about 99.4% and the grid current harmonics are considerably lower than the requirement of EN-61000-3-2 standard.

A step-down nesting-type ac–ac converter combined with voltage equalizers and switched-capacitor simple converters

In this paper, we present an inductor-less direct ac–ac converter with improved nesting-type topology. Unlike existing direct ac–ac converters, the proposed ac–ac converter combines a voltage equalizer and a switched-capacitor (SC) simple converter. Owing to the nesting conversion using two techniques, the proposed converter can provide a stepped-down voltage with small number of circuit components and high input power factor. To evaluate the performance of the proposed ac–ac converter, we compared the proposed ac–ac converter with existing inductor-less ac–ac converters, namely, flying capacitor type converter, symmetrical type converter, and traditional nesting-type converter, by theoretical analysis and simulation program with integrated circuit emphasis (SPICE) simulations. The SPICE simulations demonstrate that the proposed ac–ac converter outperforms existing inductor-less ac–ac​ converters in the point of circuit size and input power factor, although the power efficiency of the proposed ac–ac converter is inferior to that of the symmetrical type converter. In the case of 1/4× voltage gain, the proposed ac–ac converter achieves about 82% power efficiency and 0.58 input power factor when the output power is 200 W.

Design and Development of Modified BL Luo Converter for PQ Improvement in EV Charger

The existing chargers for electric vehicles (EVs) use rugged nonlinear diode bridge rectifier to avail dc voltage at the input of dc–dc converter, and introduce serious power quality issues in the input ac current. These issues set the formidable need to improve the power quality (PQ) performance of existing battery chargers by eliminating the input bridge. This is achieved in this work, by the addition of an improved PQ based bridgeless (BL) Luo converter. This power factor correction (PFC) converter is the combination of two Luo converters, which operate independently in the respective half cycles, with common input inductor. The converter provides low cost and high power density based EV charging solution as fewer number of components conduct over single switching cycle due to elimination of input diode bridge in the conventional PFC converter. The charger input current is made to follow the source voltage, exactly in phase and high input power factor is achieved. Moreover, the source current total harmonic distortion is reduced below 5% as per the IEC 61000-3-2 standard under steady state and during sudden variations at load and line side.

Modeling, Design, Analysis, and Control of a Nonisolated Universal On-Board Battery Charger for Electric Transportation

On-board chargers (OBCs) in electric transportation resolve the anxiety for frequent charging of the battery packs. This paper presents a single-phase nonisolated OBC for electric transportation using a two-switch topology. The main advantage of this OBC is that it can perform high input power quality over a wide output voltage conversion range. The presented two-switch converter is able to operate with an output voltage above and below the peak of input voltages. The analysis and various operating modes of converter and design considerations to achieve the wide output voltages are discussed in this paper. Moreover, small-signal analysis of the converter in various modes to aid for the design of the controller is also presented. A two-mode control scheme with average current-mode (ACM) control structure using PI controllers is shown in this paper with a feature of automatic mode selection. As a proof of concept, the experimental results from a 1-kW laboratory prototype with an output voltage range of 150–450 V are presented. A high input power factor of 0.99 and an efficiency of 96% have been achieved from the prototype.

Modelling of three phase SVPWM AC-AC converter using unity power factor control

This paper introduces the modelling of a novel three phase AC-AC converter with indirect use of a capacitor as DC voltage link. The proposed converter has high efficiency because it uses Space Vector PWM (SVPWM) technique at both rectificier and inverter stages to operate the pulse width modulation in IGBT switches. The novel converter is equipped with a power factor control to shape the rectifier input current waveform to be sinusoidal and to be in phase with the input voltage. To keep the DC voltage stable, the converter utilizes PI controllers. Simulations are conducted for output voltage from 120 to 300 Volts with output frequency ranging from 30 Hz to 60 Hz. The simulation results show that the converter is able to maintain stable the DC voltage and current. Furthermore, the model demonstrates the benefits of proposed converter in terms of acquiring high input power factor and sinusoidal current waveform at the output side of the inverter.

Resonant Bridgeless AC/DC Rectifier With High Switching Frequency and Inherent PFC Capability

Boost-based converters are used in a variety of non-isolated step-up applications, such as power factor correctors, because of their simplicity. The power density of these converters can be increased in higher switching frequencies, which reduces the size of the magnetic elements. This increases the switching losses, but that can be solved by soft-switching techniques. This paper proposes a resonant bridgeless power factor correction converter that provides soft switching for all of the semiconductors. The proposed structure can provide zero voltage switching for the switches and zero current switching for the diodes. In the proposed structure, the input current is inherently sinusoidal with low total harmonic distortion, even with small inductances. Therefore, a high input power factor is achieved without requiring a current control loop in the circuit. This reduces the complexity of the control circuit. An experimental prototype has been constructed to investigate the validity of the claims. Experimental results show near-unity power factor, as well as $\text{2}\%$ efficiency improvement at full load when compared to a conventional interleaved boost converter with the same components.