Single-stage High Power Factor Research Articles

Single-Stage Isolated Bridgeless Charger for Light Electric Vehicle With Improved Power Quality

A single-stage high power factor (HPF) improved power quality charging solution for light electric vehicles (LEVs) is presented in this work. The charger topology comprises a bridgeless isolated modified SEPIC (BIMSEPIC) HPF ac–dc converter, to accomplish various charging modes with high performance at the supply side. Unlike conventional bridgeless SEPIC topologies, the presented topology ensures zero circulating current through the antiparallel diode of the switch, utilizes a single switch structure, and requires simple gate drive circuitry. Further, the discontinuous conduction mode operation of the charger significantly simplifies the control complexities and associated cost of implementation. Additionally, the magnetic component's volume and switching losses are reduced considerably. Finally, the presented topology is designed, simulated, and implemented to verify its efficacy for the LEVs charging applications. A comprehensive analysis is carried out at various operating conditions, and the relevant test results are demonstrated for the performance verification. Moreover, a comparative analysis with existing chargers verifies the excellent performance of the presented charger topology.

A Novel Single-Switch Single-Stage LED Driver with Power Factor Correction and Current Balancing Capability

A novel single-switch single-stage high power factor LED driver is proposed by integrating a flyback converter, a buck–boost converter and a current balance circuit. Only an active switch and a corresponding control circuit are used. The LED power can be adjusted by the control scheme of pulse–width modulation (PWM). The flyback converter performs the function of power factor correction (PFC), which is operated at discontinuous-current mode (DCM) to achieve unity power factor and low total current harmonic distortion (THDi). The buck–boost converter regulates the dc-link voltage to obtain smooth dc voltage for the LED. The current–balance circuit applies the principle of ampere-second balance of capacitors to obtain equal current in each LED string. The steady-state analyses for different operation modes is provided, and the mathematical equations for designing component parameters are conducted. Finally, a 90-W prototype circuit with three LED strings was built and tested. Experimental results show that the current in each LED string is indeed consistent. High power factor and low THDi can be achieved. LED power is regulated from 100% to 25% rated power. Satisfactory performance has proved the feasibility of this circuit.

A Single-Stage High Power Factor Power Supply for Providing an LED Street-Light Lamp Featuring Soft-Switching and Bluetooth Wireless Dimming Capability

Light-emitting diode (LED) has the characteristics of environmental protection and energy saving, having become the lighting source of a new generation of street-light lamps. The traditional two-stage power supply for providing an LED street-light lamp is composed of an AC-DC converter with a power-factor-correction (PFC) function at the front stage and a DC-DC converter at the rear stage. The two-stage power supply for an LED street-light lamp has a large number of electronic components and costs, and the circuit efficiency is not high. Therefore, this paper presents a novel single-stage high power factor AC-DC power supply for providing an LED street-light lamp featuring soft-switching and Bluetooth wireless dimming capability through using smart tablets or smartphones to remote control the output power of the LED street-light lamp for achieving energy-saving benefits. The proposed AC-DC LED power supply integrates an interleaved buck converter circuit with coupled inductors and a half-bridge LLC resonant converter circuit into a single-stage power conversion circuit. Moreover, the coupled inductor of the interleaved buck converter circuit is designed to operate in the discontinuous conduction mode, which can naturally achieve PFC. In addition, the two power switches in the novel LED power supply have zero-voltage switching (ZVS) characteristics, which can reduce the switching losses of the power switches. The two output diodes have the characteristics of zero-current switching (ZCS), which can reduce the conduction losses of the power diodes. This paper developed a single-stage prototype circuit for providing an 144 W (36 V/4 A)-rated LED street-light lamp. According to the experimental results of the prototype circuit with an AC input voltage of 110 volts, the presented single-stage LED power supply offers high power factor (PF > 0.99), low input-current total harmonic distortion factor (THD < 3%), and high efficiency (>89%). In addition, this paper used the built-in Bluetooth wireless communication function of a smart tablet or smart phone to fulfill remote dimming control. By changing the duty ratio of the control signal, we could realize remote dimming control of 20% to 100% of the output LED street-light lamp power.

A Single-Stage High-Power Factor Converter with Synchronized Self-Excited Technique for LED Lighting

This paper proposes a single-stage, high power-factor light-emitting diode (LED) driver with a self-excited control scheme for the power switches. The self-excited mechanism is accomplished by fetching the driving voltages from a center-tapped transformer. The frequency of the driving voltages is exactly the same as the resonant frequency of the resonant converter, thus synchronizing the resonant frequency with the switching frequency and achieving zero-voltage switching (ZVS) and zero-current switching (ZCS) of power switches. The circuit topology is mainly composed of a half-bridge LC resonant converter, along with a boost-type power-factor corrector (PFC) to fulfill the single-stage structure, meaning that the presented LED driver possesses high power-factor features and low switching loss. Finally, a 40 W prototype circuit is implemented and tested, and the experimental results exhibit a satisfactory performance.

Photovoltaic based LED Lighting with Maximum Power Point Tracking

In recent years, light emitting diode (LED) has changed the scenario of residential and commercial lighting. Day lighting applications has huge scope for power saving by use of solar photovoltaic (PV) based LED lighting with DC distribution system. In this paper, a hybrid system with combination of PV and grid power has been presented. In proposed system, PV source and grid power sourced converter (GSC) operate in parallel and both are directly connected to load. GSC is mainly used for supplying the gap between the maximum PV generation and load demand. Power converter is realised using single stage high power factor grid-source converter (GSC). Maximum power point (MPP) of PV source is tracked by incremental conductance (INC) algorithm and used as feedback to control power from utility bus to load. Proposed topology is validated using 150 VA laboratory prototype and results of experimentation are given in the paper.

Single-Stage High Power Factor Converters Requiring Low DC-Link Capacitance to Drive Power LEDs

This paper proposes two nonisolated single-stage high power factor converters requiring low dc-link capacitance for power LEDs systems. Both converters result from the integration of the power factor correction and the LEDs driver stages, and require a relatively low dc-link capacitance value. A high power factor is demonstrated to be an inherent property of the proposed topologies and no input current control is necessary. The LEDs current is regulated by a symmetrical soft-switching half-bridge converter associated with a capacitive output filter. An accurate mathematical analysis valid for the two converters is detailed, yielding the elaboration of a step-by-step design procedure. In order to verify the analyses carried out, experimental results for two 90 W, 50 kHz, and 220 V converters are also presented.

Dynamics analysis of a low-voltage stress single-stage high-power factor correction ac/dc flyback converter

In this study, by integrating a power factor correction buck-boost cell with a dc/dc flyback cell and adding an auxiliary transformer for energy-divider approach, a single-stage high-power factor correction (HPFC) ac/dc flyback converter with low-voltage stress is proposed. The proposed converter exhibits the capabilities of high-power factor and low-voltage stress across the bulk capacitor when its dc/dc cell operates in continuous conduction mode. In this study, the operating principle is presented. The small-signal model of the proposed converter is also derived herein. It shows that the proposed converter with an auxiliary transformer exhibits better dynamical behaviour than the single-stage HPFC ac/dc flyback converter without an auxiliary transformer. Moreover, a proportional-integral controller is well designed for output voltage regulation. Finally, the accuracy of theoretical analysis and performances of overall system are thereby validated by experimental results.

Single-stage high power factor step-up/step-down isolated AC/DC converter

This study presents a single-stage (S 2 ) isolated current rectifier with power factor correction, based on a full-bridge flyback converter. This converter is designed to operate with adjustable output voltage so that it can operate in two distinct operation modes, step-up or step-down, depending on the input and output voltages. The proposed converter presents some features that make it attractive for many applications, such as constant switching frequency, step-down and step-up operation, high power level capability and the absence of an auxiliary pre-loading circuit to control the inrush current. This study presents the theoretical analysis of the converter for continuous conduction mode as well as experimental results based on a 3 kW prototype.

Single-stage single-switch PFC converter for wide-input extreme step-down voltage applications

SUMMARY This paper presents a new single-stage single-switch high power factor correction AC/DC converter suitable for low-power applications (< 150 W) with a universal input voltage range (90–265 Vrms). The proposed topology integrates a buck–boost input current shaper followed by a buck and a buck–boost converter, respectively. As a result, the proposed converter can operate with larger duty cycles compared with the existing single-stage single-switch topologies, hence, making them suitable for extreme step-down voltage conversion applications. Several desirable features are gained when the three integrated converter cells operate in discontinuous conduction mode. These features include low semiconductor voltage stress, zero-current switch at turn-on, and simple control with a fast well-regulated output voltage. A detailed circuit analysis is performed to derive the design equations. The theoretical analysis and effectiveness of the proposed approach are confirmed by experimental results obtained from a 100-W/24-Vdc laboratory prototype. Copyright © 2011 John Wiley & Sons, Ltd.

A novel single-stage isolated high power factor correction converter with low voltage stress: dynamics and control

The dc/dc part of a single-stage high power factor correction (HPFC) converter generally operates in continuous conduction mode to increase the output power. However, this results in a high voltage stress across the bulk capacitor of the converter at light loads. The negative magnetic feedback technique is widely applied to deal with this problem. Unfortunately, a dead band in the input current is usually caused by the negative magnetic feedback, which reduces the power factor. To overcome this drawback, a novel single-stage isolated HPFC converter with low voltage stress is proposed in this study. A high power factor is maintained even though the negative magnetic feedback technique is employed in the proposed converter. Output voltage regulation in response to variations in the line voltage and load resistance is also considered in this study. The dynamics of the proposed converter are investigated and a voltage controller is then designed. Finally, the performance of the proposed converter is experimentally verified.

Non-isolated single stage PFC rectifier for wide-input large step-down voltage applications

This paper proposes a non-isolated single-stage high power factor rectifier suitable for applications requiring low-voltage and high-current output. The proposed converter integrates two buck-boost converters with a buck converter. As a result, the proposed converter can operate over a wide range of input voltage with extended low output voltage capability, making it suitable for universal input applications. The proposed topology utilises two synchronised non-floating power switches with low current stress. Additional features are gained when the converter operates in discontinuous conduction mode (DCM). These features include low semiconductors voltage stress, zero-current switch at turn-on, and simple control with a fast well-regulated output voltage and near unity input power factor. Closed form equations of the design constraints for the proposed topology are presented. Simulation and experimental results are presented to demonstrate the feasibility of the proposed technique.

Single-stage high power factor half-bridge resonant technique for linear ultrasonic motor driving circuit

This study addresses the design and analysis of a single-stage high power factor half-bridge driver, which is composed of a half-bridge resonant inverter and a buck-boost converter, for a linear ultrasonic motor (LUSM). LUSMs have found their applications in miniaturised actuators and precision position manufacturing industries due to their merits of miniaturisation and high resolution. The triggering signals of both the active switches are generated using asymmetrical pulse-width modulation technique to achieve zero-voltage switching and zero-current switching using proper designed circuit parameters. Then, liquid chromatography resonant technique is adopted to produce 39.6 kHz sinusoidal voltage output. A laboratory-made circuit is built to test the circuit topology. Satisfying results are obtained to verify the validity of the proposed topology.

Analysis and Design for a Novel Single-Stage High Power Factor Correction Diagonal Half-Bridge Forward AC&amp;#8211;DC Converter

By means of components placement, the buck-boost and diagonal half-bridge forward converters are combined to create a novel single-stage high power factor correction (HPFC) diagonal half-bridge forward converter. When both the PFC cell and dc–dc cell operate in DCM, the proposed converter can achieve HPFC and lower voltage stress of the bulk capacitor. The circuit analysis of the proposed converter operating in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$ DCM+ DCM$</tex> mode is presented. In order to design controllers for the output voltage regulation, the ac small-signal model of the proposed converter is derived by the averaging method. Based on the derived model, the proportional integral (PI) controller and minor-loop controller are then designed. The simulation and experimental results show that the proposed converter with the minor-loop controller has faster output voltage regulation than that with the PI controller despite the variations of line voltage and load. Finally, a 100-W prototype of the proposed ac–dc converter is implemented and the theoretical result is experimentally verified.

Single-stage high power factor electronic ballast for fluorescent lamps with constant power operation

A single-stage high power factor electronic ballast is designed to operate fluorescent lamps at a constant power over a very wide input voltage range. The electronic ballast performs the constant power operation by adjusting the duty-ratio of the embedded power regulation circuit. With duty-ratio control, a preheating period for the cathode filaments can be provided before igniting the lamp. The operation of the electronic ballast is discussed by an illustrative example with experimental results.