AC-DC Power Supply Research Articles

Design and Reliability Evaluation of 5-V output AC-DC Power Supply Module for Electronic Home Appliances

Design and Reliability Evaluation of 5-V output AC-DC Power Supply Module for Electronic Home Appliances

Shunt active power filter-based approach for arc fault detection

In this paper, we present a novel method based on a single-phase active power filter (APF) for series arc faults detection in an AC electrical installation. The APF's reference current is used as the starting point for our method tested on a large variety of loads: resistors, vacuum cleaner, rotary drill, dimmer and AC-DC power supplies. Firstly, the proposed method is validated at the simulation level using the Matlab software and then experimentally using the Hardware-In-the-Loop (HIL) approach with an FPGA Altera Stratix III prototyping board. The results obtained in this work show that series arc faults can be successfully detected with an APF, only by updating its digital control with the arc fault detection functionality, instead of designing from the very beginning an arc-fault detection specific device.

Modeling, Simulation and Design of an AC-DC Power Supply

This paper presents a very simple simulation technique that is able to predict the behavior of a regulated AC-DC power supply. The proposed technique can be easily implemented in an open-source platform for numerical computation. Besides, it allows the simulation of any component, unlike commercial simulation software that has a limit number of components. The information given by the simulation technique is of paramount importance for the selection of the electronic components that compose the power supply. To show the applicability of the proposed technique an experimental prototype was designed, and used for validation purposes. Additionally, a short description about the major capacitor technologies used in power electronics is also presented.

Disrupted bandcount doubling in an AC-DC boost PFC circuit modeled by a time varying map

Power factor correction converters are used in many applications as AC-DC power supplies aiming at maintaining a near unity power factor. Systems of this type are known to exhibit nonlinear phenomena such as sub-harmonic oscillations and chaotic regimes that cannot be described by traditional averaged models. In this paper, we derive a time varying discretetime map modeling the behavior of a power factor correction AC-DC boost converter. This map is derived in closed-form and is able to faithfully reproduce the system behavior under realistic conditions. In the chaotic regime the map exhibits a sequence of bifurcation similar to a bandcount doubling cascade on the low frequency. However, the observed scenario appears in some sense incomplete, with some gaps in the bifurcation diagram, whose appearance to our knowledge has never been reported before. We show that these gaps are caused by high frequency oscillations.

A Novel Control Scheme for Power Factor Improvement in Modified Bridgeless Boost Converter

In Green Energy technologies like wind energy conversion systems and Domestic applications like SMPS and UPS systems, the input voltage amplitude and input frequency are time varying in nature. Fast-Escalating and extremely challenging high efficiency requirements for AC-DC power supplies for notebooks, desktop computers are to minimize the power losses (Conduction losses). In the conventional rectifiers power losses are more and power factor is poor resulting in loss of efficiency. Normally, the bridgeless topologies, also referred to as dual boost power factor correction (PFC) rectifiers, may reduce the conduction losses by reducing the number of semi-conductor components in the line current path. Power supply units have to make the load compatible with the source. The presence of non-linear load results in poor power factor operation and produces harmonic components in the line. So PFC techniques are necessary to meet harmonic regulations and standards such as IEC 61000-3-2 and IEEE 519. A modified bridgeless topology may be used for such applications. A novel switching controller is developed that regulates the input resistance to a desired value. Hence input power factor is unity and also the total harmonic distortion is controlled to a tolerable limit. In the proposed model, the modified bridgeless boost converter is activated in to a pure resistance mode. Finally the performance of the modified bridgeless boost converter is compared with the existing basic bridgeless boost converter.

Suppression of Line Frequency Instabilities in PFC AC-DC Power Supplies by Feedback Notch Filtering the Pre-Regulator Output Voltage

Due to nonlinear effects, Power Factor Correction (PFC) ac-dc converters working in Continuous Conduction Mode (CCM) can exhibit nonlinear phenomena such as subharmonic oscillations and chaotic regimes at the line frequency. These undesirable behaviors increase the Total Harmonic Distortion (THD) and shift the dc input line current to non null values. This results in a malfunctioning of the system or even damages caused by the increase of the temperature which can jeopardize enormously the performances and shorten the lifetime of the system. In order to avoid these problems, subharmonic line frequency instabilities must be suppressed. In this paper, a selective notch filter based controller is combined with the output voltage compensator to suppress these instabilities and to stabilize a two-stage PFC ac-dc converter. A frequency domain analysis is used to explain the control mechanism of directing subharmonic and chaotic oscillations into stable periodic motion. A detailed study of the effect of this selective filter on the dynamical behavior of the system is presented. A simple harmonic model is used to obtain the control stability domain. This control technique is simple and allows widening the stability domain and improving the performances of the system being its experimental implementation possible using standard devices such as OAs and passive elements. The correctness of the proposed technique is verified with numerical simulations and experimental measurements.

The Application of Intelligent AC-DC Integrated Power Supply System in 500kV Switching Station

The paper proposed an application of intelligent AC-DC integrated power supply system in 500kV switching station. Firstly, this paper introduced current situation of AC-DC power supply system which is for home use and provided main components of this intelligent power supply system and its functions. And then, all cautions in operation and maintenance process is explained. Lastly, this paper summarized problems exposed in the system after running half year in 500kV switching station and put forward some aspects needed to be improved.

On the Limit of the Output Capacitor Reduction in Power-Factor Correctors by Distorting the Line Input Current

Active power-factor correctors (PFCs) are needed to design ac-dc power supplies with universal input voltage range and sinusoidal input current. The classical method to control PFCs consists in two feedback loops and an analog multiplier. Hence, the input current is sinusoidal and it is in-phase with the input voltage. However, a bulk capacitor is needed to balance the input and the output power. Due to its high capacitance, an electrolytic capacitor is traditionally used as a bulk capacitor in PFCs. As a consequence, the lifetime of the ac-dc power supply is limited by the electrolytic capacitor's, which becomes insufficient to some applications (e.g., high-brightness LEDs). This paper proposes a reduction of the output voltage ripple (which allows reduction of the output capacitance) by distorting the input current, but maintaining the harmonic continent compatible with EN 61000-3-2 regulations. The limits of this output capacitor reductions are deduced. Also, a control strategy based on a low-cost microcontroller is developed to put the proposed study into practice. Finally, the theoretical results are validated in a 500-W prototype.

Correction Technology and Development on Active Power Factor

Correction Technology on active power factor is now widely used in AC-DC power supply circuit to eliminate harmonic of power system, to improve the power factor. Firstly the method of power factor correction technology is set out. Secondly, the basic principle of active power factor correction technology is analyzed, then the control method for active power factor correction technology is given. Finally the development trend of active power factor correction technology is analyzed.

A universal‐input high‐power‐factor power supply without electrolytic capacitor for multiple lighting LED lamps

SUMMARYThe AC–DC power supply for LED lighting application requires a long lifetime while maintaining high‐efficiency, high power factor and low cost. However, a typical design uses electrolytic capacitor as storage capacitor, which is not only bulky but also with short life span, thus hampering performance improvement of the entire LED lighting system. In this article, a SEPIC‐derived power factor correction topology is proposed as the first stage for driving multiple lighting LED lamps. Along with a relatively large voltage ripple allowable in a two‐stage design, the proposal of LED lamp driver is able to eliminate the electrolytic capacitor while maintaining high power factor and high efficiency. To further increase the efficiency of LED driver, we introduced and used the twin‐bus buck converter as the second‐stage current regulator with Pulse Width Modulation (PWM) dimming function. The basic operating principle and the deign consideration are discussed in detail. A 50‐W prototype has been built and tested to verify the proposal. Copyright © 2011 John Wiley & Sons, Ltd.

Analysis and Design Optimization of Magnetic-Feedback Control Using Amplitude Modulation

In offline AC-DC and high-voltage DC-DC power supplies, galvanic isolation between the input and output is often implemented with optocoupler feedback. However, several disadvantages exist when implementing optocoupler feedback, such as a variable loop gain due to optocoupler tolerance and sensitivity to temperature, as well as a relatively high cost. An alternative to optocoupler feedback is to use magnetic feedback, which can be designed to have insensitivity to component tolerance, and good temperature stability. Although magnetic feedback has been in use for many years, a detailed analysis and clear design procedure has not been presented in the literature. This paper presents a thorough analysis of a magnetic-feedback implementation, and provides a comprehensive design procedure that is verified on a 7-V/15-W experimental prototype.

Fully Soft-Switched Three-Stage AC–DC Converter

The paper presents a fully soft-switched three-stage ac-dc power supply for server applications. In this three-stage architecture, the front-end boost power factor correction (PFC) is followed by a dc-dc boost converter that serves as a preregulator to the isolated dc-dc output stage. Through magnetic integration, soft switching of all semiconductor switches in the PFC boost converter and the dc-dc boost preregulator is achieved in addition to a reduced number of magnetic components. Generally, the output dc-dc stage can be implemented with any isolated topology. In this development, a zero voltage switching half-bridge dc-dc converter is employed for the third stage. The performance of the proposed three-stage approach was evaluated on a 700-W/12-V, universal-line-range ac-dc prototype.

Development of Quench Detection System for W7-X

The Quench Detection System of W7-X will consist of nearly 400 Quench Detection Units (QDU) for the fast and reliable supervision of the 70 superconducting coils and the 120 superconducting bus bar sections. There will be five control racks with about 80 QDU, a data acquisition unit, an ac–dc power supply with integrated dc UPS unit in each of the racks and a PC based data management system as an overlay structure. Each QDU will have a special analogue input circuit realised as a programmable half bridge front end with different polarity-sensing and limiting functions for suppressing high dynamic voltages. Special filter design is included for noise-suppression and over voltage protection. A reconfigurable control/arithmetic unit offers possibilities of future expansions (e.g. all digital evaluation). The QDU acquires and checks the differential voltages of the superconductors permanently. In case of a quench it triggers the fast discharge of the coils and the storage of the voltage signals on the memory unit. The quench signals are in the mV range and have to be clearly identified within a noisy and a high-voltage background within a few milliseconds. Each QDU transfers the stored signal dates via a high-speed RS485 serial interface with 20 kV optical isolation barrier to an industrial type data acquisition unit. A second optically isolated RS485-network enables interconnection of each QDU in the control rack (Compound-Mode of QDU). The QDU are designed with an internal failsafe, programmable self-test and redundancy feature, broken wire check of the quench detection cables and connectors inside and outside of the cryostat of W7-X. All QDU will be fed via an UPS supported 24 V dc bus through a high voltage isolated dc–dc transformer on each unit. The design of the Quench Detection System allows operation under high voltage levels of up to 8 kV and under magnetic stray field levels up to 30 mT. The front end is very well isolated and the outputs of the QDU are strictly separated by optical isolating transformers. The differential inputs are equipped with 500 V short-time over voltage protection. The paper gives an overview of the design of the first prototype.

Hold-up time extension Circuit with integrated magnetics

A circuit that substantially extends the hold-up time of ac-dc power supplies is introduced. By using integrated magnetics, the power density of this hold-up time extension circuit is maximized. The performance of the proposed approach was evaluated on a universal line range 1-kW power supply.

High efficiency fuel cell based uninterruptible power supply for digital equipment

Eliminating the ac–dc converter (such as a computer's power supply), in a dc system when using a fuel cell based uninterruptible power supply (UPS), serves several primary functions. Firstly, it eliminates the need for a dc–ac inverter, and secondly, it eliminates a usually highly inefficient component—the power supply. Multiple conversions result in multiple inefficiencies. By replacing the computer's ac power supply with a high efficiency dc power supply capable of operating directly from a fuel cell – and thereby eliminating the inverter – the overall efficiency of the UPS can be increased by 50% or more. This is essential considering that the primary function of a fuel cell based UPS is long-term operation of the system, and poor efficiency equates to higher fuel consumption. Furthermore, inefficient systems have greater power demands, and therefore a larger fuel cell stack is needed to power them. At the present cost of fuel cell systems, this is a considerable problem. The easiest way to accomplish a direct dc UPS is to replace the computer's ac–dc power supply with a dc–dc power supply.

A Novel EMI Filter Design Method for Switching Power Supplies

This work introduces an improved and simplified method to design electromagnetic interference (EMI) filters for both dc-dc and ac-dc switching power supplies. This method uses the practical approach of measuring the power supply noise spectrum and using the data to calculate the maximum possible magnitude and minimum possible magnitude of the differential mode and common mode noise impedances. The noise impedance magnitude information aids the design of the EMI filter. Phase information for the noise impedance is not required. In addition, information about the topology and control method of the power supply is not needed. This method solves the limitations of existing EMI filter design methods, which are either too complicated to use, or are based on ideal cases that neglect the noise impedance. The analysis and experimental results show that this method can guarantee that the required attenuation can be achieved, especially at low frequencies.

Series-resonant single-phase AC-DC power supply with control of reactive power

It is shown that the resolution of the high-frequency input current of the series-resonant converter leads to the possibility of accurately controlling the waveform of the source current. In combination with the accurate positioning of the high-frequency current pulses, it is possible to influence the exchange of power with the source by introducing active filtering. A power factor equal to one would lead to optimal operation. However, the zero crossing of the AC source voltage, introduces the need to store energy. Bulky low-frequency storage elements increase the specific volume and weight of the converter, while the exchange of energy with storage elements decreases the overall efficiency. The energy stored in the resonant circuit is fundamentally too low to solve this problem. The stored energy in the output capacitor necessary to decrease the high-frequency ripple voltage is available for these purposes. To meet the optimal conditions for the power factor at the source, a bipolar flow of energy is required.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>