High Input Power Factor Research Articles

A Primary-Side Control Scheme for High-Power-Factor LED Driver With TRIAC Dimming Capability

This paper proposes a primary-side control scheme for low-power light-emitting diode (LED) driver with Flyback topology. With average primary-side current signal and transformer auxiliary winding voltage signal, the output current can be derived and regulated precisely by the proposed control scheme without any isolated feedback circuit. Furthermore, the proposed primary-side control scheme can be implemented with power factor correction control to achieve high input power factor, which is usually required for LED drivers. Since the triode for alternating current (TRIAC) dimming is very popular in practical application, it is preferred that the LED driver can also be compatible with TRIAC dimming. With the proposed control scheme, the input characteristic of the LED driver is resistive like an incandescent bulb. No extra dummy load is needed to provide the TRIAC holding current. Both the output current signal and TRIAC dimming signal can be obtained at the primary side, the TRIAC dimming function can be easily implemented and linear dimming characteristic can be achieved. Detailed operation principles and design considerations of the proposed control scheme are presented in the paper. The experimental results from a 15-W prototype verify the theoretical analysis.

Wireless energy transmission device with thrust for transportation

The characteristics in the linear induction motor (LIM) mode of new wireless energy transmission device are cleared analytically. The apparatus operates as two types of LIM with propulsion force or a linear transformer without thrust. One type of the LIM is a secondary current controlled wound type of LIM with primary winding on ground and the other is the LIM with reaction plate on ground. The paper shows the characteristics of the wound type of LIM in power running and has the onboard power transmission function even in the power running. The two-dimensional finite element method (FEM) is used for the analysis. As a result, it is cleared that the model designed for urban transit has high efficiency and high input power factor respectively more than 0.9 for the optimal control.

Design of Control System Used for Cells Cascaded Multilevel Converter Based on TMS320F2407

Because of its advantages, such as low input and output harmonics, high input power factor and efficiency, cells cascaded multi-level converter is widely used in the field of variable voltage and variable frequency control. Through the analysis of the multi-level converter’s structure and its PWM (Pulse Wavelength Modulation) control theory, a new structure of control system based on TMS320F2407 DSP was proposed. The control system structure and components of the central system and subsystem are given in this paper. SPWM control was achieved and multi-level PWM inverter output waveforms were produced. The results show that this type of multi-level inverter has superior performance.

Three-phase single-switch boost power factor correction converter with high input power factor

Three-phase single-switch boost power factor correction (PFC) converter features zero-current turn-on for the switch, no reverse recovery in diode, constant frequency operation, simple control and low cost and it is suitable for low-to-medium power conversions. However, the input power factor (PF) is relatively low when the duty cycle is constant in the whole line cycle. This study analyses the operation principle of the three-phase single-switch boost PFC converter, and the expressions of the input current and PF are derived, based on which, a variable duty cycle control is proposed so as to improve the PF and reduce the input current harmonics. A method of fitting the duty cycle is further proposed for simplifying the circuit implementation. Besides a higher PF and lower input current harmonics, the proposed variable duty cycle control achieves a lower output voltage ripple and a higher efficiency over the constant duty cycle control. A 3 kW prototype has been built and tested in the laboratory, and the experimental results are presented to verify the effectiveness of the proposed method.

A High-Efficiency Single-Phase AC/DC Converter With Enabling Window Control and Active Input Bridge

The conventional continuous conduction mode boost converter has been widely used for power factor correction (PFC) applications because of its high input power factor and simplicity, but it suffers from conduction loss in the input rectifier bridge and switching loss due to the high switching frequency. The efficiency decreases significantly under the low input voltage or the light-load work condition. In this paper, a novel enabling window control (EWC) method is introduced to reduce the switching loss, and an active input bridge is used to replace the traditional diode bridge for high efficiency. The proposed EWC method is easy to implement with existing PFC ICs, and only a few additional control components are needed. Moreover, electromagnetic interference noise and driving loss of the main switch can be reduced with the EWC method. Semiconductor devices with competitive price can be used to reach efficiency as high as SiC diode and Cool-MOSFETs. A self-driven circuit is also used for the active bridge. The principle and design of proposed method are presented and the validity of the proposed method is verified by experimental results obtained from a 500-W prototype.

Elimination of an Electrolytic Capacitor in AC/DC Light-Emitting Diode (LED) Driver With High Input Power Factor and Constant Output Current

While LEDs enjoy relatively long lifetime up to 10 years, the lifetime of traditional LED drivers using electrolytic capacitor as storage element is limited to typically less than 5 years. In this paper, an ac/dc LED driver without electrolytic capacitor is studied. Compared with other methods to eliminate electrolytic capacitor, the proposed driver has the advantages of almost unity input power factor and constant output current for LEDs. The operation principle, detailed design procedure of the main circuit, and control strategy are presented. The feasibility of the proposed converter has been successfully verified by experiments.

Simulation Study of PFC Boost Converter Based on Predicted Average Current Control

Introduced to predict average current control PFC Boost converter structure, and analyzes its operating principle, the average current control strategies equation is given by derivation. And a model of predict average current control PFC Boost converter is gained using Matlab Simulink simulation software and SimPowerSystems toolbox. Simulation results show that the predicted average current control PFC Boost converter with control circuit is simple and reliable, high input power factor, anti-interference ability, current harmonic distortion, etc, and is forecast to average voltage control strategy for the active power factor correction provides a novel, simple and feasible control methods.

A Modified Single-Phase Quasi-Z-Source AC–AC Converter

A modified single-phase quasi-Z-source ac-ac converter is proposed in this paper. The proposed converter has the main features in that the output voltage can be bucked or boosted and be both in-phase and out-of-phase with the input voltage. The input voltage and output voltage share the same ground, the size of a converter is reduced, and it operates in a continuous current mode. A safe-commutation strategy for the modified single-phase quasi-Z-source ac-ac converter is used instead of a snubber circuit. The operating principles and a steady-state analysis are presented. A laboratory prototype, tested using a resistive load, a passive load, and a nonlinear load, was constructed that used an input voltage of 70 Vrms /60 Hz in order to verify the performance of the modified single-phase quasi-Z-source ac-ac converter. The experimental results verified that the converter has a lower input current total harmonic distortion, a higher input power factor, and a higher efficiency in comparison to a conventional single-phase Z-source ac-ac converter. In addition, the experimental results show that the use of the safe-commutation strategy is a significant improvement, as it makes it possible to avoid voltage spikes on the switches.

Cascade Three-Level AC/AC Direct Converter

This paper proposes a novel family of cascade three-level (TL) ac-ac direct converters based on ac switch cells, which transfer unsteady high ac voltage with distortion into regulated sinusoidal voltage with low total harmonic distortion (THD). The topological family includes buck TL-boost, buck-boost TL, and buck TL-boost TL modes. In order to achieve a reliable TL ac-ac conversion, a double transient voltage feedback control strategy of the output voltage and the voltage across the flying capacitor is introduced in this paper. A 500-VA 220-V ±10% 50-Hz ac/220-V 50-Hz ac prototype is presented with the experimental results to prove that the converters have four improved advantages simultaneously, including lower voltage across power switches, bidirectional power flow, low THD of output voltage, and higher input power factor.

Design and Implementation of a Photovoltaic High-Intensity-Discharge Street Lighting System

This paper presents a photovoltaic (PV) high-intensity-discharge (HID) street lighting system. A single-ended primary inductance converter (SEPIC) is studied for maximum power point tracking (MPPT) and battery charging. High conversion efficiency and high MPPT accuracy can be achieved under different atmospheric conditions. A pulse-current-charging scheme with an adaptive rest-period is also applied to avoid battery overcharging. An electronic ballast circuit is also designed to release the solar energy stored in battery for powering HID lamps. The studied PV HID street lighting system is connected to the ac-line utility with a SEPIC power factor correction converter. High input power factor can be achieved when energy is drawn from the ac-line utility to drive the HID lamp and to prevent the battery from over-discharging. The proposed PV HID street lighting system has the advantages of high power density, simple circuit, and long lifetime. The operating principle and design considerations were analyzed and discussed in detail. A laboratory prototype was implemented and tested. The experimental results were shown to verify the feasibility of the proposed scheme.

Novel Family of Single-Stage Three-Level AC Choppers

The capacitor-clamped base cell is presented. Based on the base cell, a novel family of single-stage three-level (TL) ac choppers is proposed. The converters can directly transfer unsteady high ac voltage with distortion into regulated sinusoidal voltage with low THD. The circuit configuration is constituted of a TL converter, and input and output filters. The topological family includes buck, boost, buck-boost, Cuk, Sepic, and Zeta modes. In order to achieve a reliable TL ac-ac conversion, a double transient voltage feedback control strategy of output voltage and the voltage across the clamp capacitor is introduced in this paper. A prototype of a 500 VA 220 V ± 10% 50 Hz ac/180-240 V 50 Hz ac converter is presented with the experimental results to prove that the converters have four improved advantages simultaneously, including the lower voltage stress of power switches, the bidirectional power flow, the low total harmonic distortion of output voltage, and the higher input power factor.

Two-Stage Isolated Switch-Mode Power Supply With High Efficiency and High Input Power Factor

This paper presents the conception and analysis of a switch-mode power supply (SMPS) with desirable characteristics of high-frequency isolation, high input power factor, low harmonic distortion, and high efficiency. Nearly unity input power factor can be obtained by using an interleaved boost converter associated with a nondissipative snubber, as high efficiency of the ac–dc front-end stage results. Additionally, a soft-switching full-bridge topology performs the dc–dc conversion, providing isolation to the SMPS by using a high-frequency transformer. By cascading both stages, the aforementioned characteristics are achieved. Theoretical background on each one of the converters is presented, and experimental results obtained from a laboratory prototype are presented and discussed in order to validate the proposal. In addition, the evaluation tests demonstrate the operation with nearly unity power factor, high efficiency, and good dynamic response over a wide load range.

A Novel Passive Offline LED Driver With Long Lifetime

This paper describes a patent-pending passive offline light-emitting diode (LED) driver that has no controlled semiconductor switches, electrolytic capacitors, auxiliary power supply, and control board. It can provide a fairly smooth current from the ac mains to drive LED strings. The new circuit has the advantages of high input power factor, high energy efficiency and luminous efficacy, long lifetime, stable luminous output, and high robustness against extreme weather conditions. In addition, over 90% of the driver material is recyclable, leading to reduction of electronic waste. It is particularly suitable public LED lighting systems, such as road lighting systems. Experimental results based on a 50-W system are included in the paper to confirm the validity of the proposal. Due to the circuit simplicity, an energy efficiency exceeding 93.6% has been achieved.

Single-Phase AC–AC Converter Based on Quasi-Z-Source Topology

This paper deals with a new family of single-phase ac-ac converters called single-phase quasi-Z-source ac-ac converters. The proposed converter inherits all the advantages of the traditional single-phase Z-source ac-ac converter, which can realize buck-boost, reversing, or maintaining the phase angle. In addition, the proposed converter has the unique features that the input voltage and output voltage share the same ground and the operation is in the continuous current mode. The operating principles of the proposed converter are described, and a circuit analysis is provided. In order to verify the performance of the proposed converter, a laboratory prototype was constructed with a voltage of 84 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rms</sub> /60 Hz. The simulation and experimental results verified that the converter has a lower input current total harmonic distortion and higher input power factor in comparison with the conventional single-phase Z-source ac-ac converter.

Principle of designing slope compensation in PFC Boost converter

Due to wide input fluctuation with line frequency of 50 Hz, power-factor-correction (PFC) Boost converters tend to exhibit fast-scale instability over time domain. The traditional remedy is to impose slope compensation so as to weaken or eliminate this instability. A theoretical principle on the implementation of slope compensation signal is still lacking. Empirical design will induce over compensation frequently, resulting in a large decrease of power factor. In order to tackle this issue, by constructing the discrete-time iterative map of the PFC Boost converter from the viewpoint of bifurcation control theory of nonlinear systems, consequently, the criterion of critical stability for the PFC circuit can be established. Based on this stability criterion, appropriate design of slope compensation can be achieved. Our work indicates that 3 main circuit parameters (i.e. switching cycle, output reference voltage and inductor) determine the effective amplitude design of the slope compensation signal. The results, validated by a large quantity of analytical and numerical studies, show that appropriate slope compensation can be effective in weakening (or controlling) fast-scale bifurcation while maintaining a rather high input power factor.

Input Current Harmonics in a Regenerative Multicell Inverter With Single-Phase PWM Rectifiers

Harmonics are a very important issue in the design and operation of medium-voltage inverter drives, due to restrictions imposed by regulations. This paper studies the harmonics generated by a three-phase multicell cascade inverter, with single-phase pulsewidth modulation rectifiers at the input side of each cell; thus, the entire topology is able to regenerate power to the net. This paper identifies accurately the harmonic generation process in the dc-link voltage, the input current of each cell, and, therefore, at the input side of the inverter. Moreover, this paper proposes a method to reduce and, in some cases, eliminate the input current harmonics, reaching a very high input power factor for any operation condition. Simulation and experimental results are provided to validate the theoretical analysis.

Proposal of a Soft-Switching Single-Phase Three-Level Rectifier

This paper is concerned with the study of a single-phase boost-type three-level rectifier. The converter is supposed to present high input power factor, low current harmonics, low total harmonic distortion, and simple control scheme. In order to minimize switching losses, a passive nondissipative snubber is associated with the aforementioned converter. The theoretical analysis, design procedure, and analytical results regarding a 1.2-kW prototype are presented to validate the proposal.

Input Current Harmonics in a Regenerative Multicell Inverter With Single-Phase PWM Rectifiers

Harmonics are a very important issue in the design and operation of medium-voltage inverter drives, due to restrictions imposed by regulations. This paper studies the harmonics generated by a three-phase multicell cascade inverter, with single-phase pulsewidth modulation rectifiers at the input side of each cell; thus, the entire topology is able to regenerate power to the net. This paper identifies accurately the harmonic generation process in the dc-link voltage, the input current of each cell, and, therefore, at the input side of the inverter. Moreover, this paper proposes a method to reduce and, in some cases, eliminate the input current harmonics, reaching a very high input power factor for any operation condition. Simulation and experimental results are provided to validate the theoretical analysis.

A Novel Soft-Switching Single-Phase AC&amp;#x2013;DC&amp;#x2013;AC Converter Using New ZVS&amp;#x2013;PWM Strategy

This paper proposes a novel soft-switching single- phase ac-dc-ac converter to give high input power factor and low current distortion on the rectifier side and provide clean and stable ac voltage on the inverter side. The proposed converter uses a new zero voltage switching (ZVS) strategy to get ZVS function. Besides operating at constant frequency, all semiconductor devices operate 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 is 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 the rectifier side of proposed converter to detect the transition time and synthesize a suitable low harmonics sinusoidal waveform for the input current. The sinusoidal pulsewidth modulation (SPWM) control strategy is employed in the inverter of proposed converter to achieve good dynamic regulation. A design example of 1000 W soft-switching single-phase ac-dc-ac converter is examined to assess the converter performance.

A Novel Single-Switch Single-Stage Electronic Ballast With High Input Power Factor

This paper proposes high-power-factor electronic ballast for fluorescent lamps. The converter offers a high input power factor and a high-frequency supply to the lamp using a single switch. Besides the simple circuit configuration, the excellent performances of high power factor for ac input side and low lamp crest factor for lamp are included in this paper. The conventional electronic ballast circuit has larger conduction losses because its power flow path of power factor correction (PFC) circuit always includes two diode losses from the front-end bridge rectifier and one power switch loss. The PFC power flow path of the proposed circuit has three semiconductor conduction drops when the active switch is on and two semiconductor conduction drops when the active switch is off. Therefore, it can provide lower conduction loss than the conventional one. The design equations are derived from the analyzed results based on fundamental approximation, and then an easy-to-use design tool is provided accordingly under considerations of filament heating and ignition. A prototype circuit that operates at 40-kHz switching frequency and 110-V line voltage for one 40-W fluorescent lamp is built and tested to verify the analytical predictions