Input Current Shaping Research Articles

Single Phase Single Stage AC/DC Converter with High Input Power Factor and Tight Output Voltage Regulation

A single stage single switch AC/DC converter is an integration of input current shaper and a DC/DC cell with a shared controller and one active switch. The converter is applicable for digital input power supply with high input power factor and tight output voltage regulation. The focus of the topology is to reduce the DC bus voltage at light load without compromising with input power factor and voltage regulation. The concept behind this topology is direct power transfer scheme. Using special configuration of DC/DC cell does reduction of DC bus voltage and DC/DC cell works on the principle of series charging and parallel discharging. The power output of this converter can go up to 200W.

A Novel Forward AC/DC Converter With Input Current Shaping and Fast Output Voltage Regulation Via Reset Winding

This work presents a novel simple forward AC/DC converter with harmonic current correction and fast output voltage regulation. In the proposed AC/DC converter, a transformer incorporating reset winding provides two main advantages. First, the bulk inductor used in the conventional boost-based power-factor-correction cell is omitted in the proposed converter, allowing significant volume and weight of magnetic material to be saved. Second, the voltage across the bulk capacitor can be held under 450 V by adjusting the transformer winding ratio, despite the converter operating in a wide range of input voltages (90/spl sim/265 V/AC). This new converter complies with IEC 61000-3-2 under a load range of 200 W and has fast output voltage regulation.

A Different Approach to Implement an Active Input Current Shaper

In recent years, several AC/DC converters have been presented in order to meet the power quality regulations, while maintaining the lowest number of components with the purpose of minimizing the cost and complexity; for this purpose the active input current shaping technique was proposed. A new active input current shaper (AICS) is presented. Differently from the traditional series AICS, the proposed scheme connects the auxiliary output of the main converter in parallel with the rectified AC mains instead of the series connection. The proposed parallel scheme demands a current with a low harmonic content where the standard specifications are fulfilled. The operation, simulation, and experimental results of the proposed scheme are presented.

Novel Concept for Mains Voltage Proportional Input Current Shaping of a VIENNA Rectifier Eliminating Controller Multipliers

This paper proposes a novel mains voltage proportional input current control concept eliminating the multiplication of the output voltage controller output and the mains ac phase voltages for the derivation of mains phase current reference values of a three-phase/level/switch pulsewidth-modulated (VIENNA) rectifier system. Furthermore, the concept features low input current ripple amplitude as, e.g., achieved for space-vector modulation, a low amplitude of the third harmonic of the current flowing into the output voltage center point, and a wide range of modulation. The practical realization of the analog control concept as well as experimental results for application with a 5-kW prototype of the pulsewidth-modulated rectifier are presented. Furthermore, a control scheme which relies only on the absolute values of the input phase currents and a modified control scheme which does not require information about the mains phase voltages are presented.

Input current wave‐shaping technique using inductor voltage sensing for high‐power‐factor flyback rectifier

AbstractIn this paper, a simple input current waveform shaping method for a rectifier with a high power factor using the induced voltage of a flyback transformer is proposed. The duty ratio of the present shaping circuit is obtained by comparison of the integration signal of the rectified induced voltage and the ramp carrier waveform with a negative slope. By means of the proposed method, the input voltage sensor, current control loop, multiplier, and inductance current sensor can be eliminated, simplifying the control circuit. In order to confirm the proposed method, a flyback rectifier circuit for 100 W is fabricated for an experimental investigation. The results confirm that the input current waveform of the rectifier becomes closer to a sinusoidal shape and harmonic components become smaller by the use of the present shaping method. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 87(10): 26–35, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10188

A Parallel-Connected Single Phase Power Factor Correction Approach With Improved Efficiency

In this paper, a new parallel-connected single phase power factor correction (PFC) topology using two flyback converters is proposed to improve the output voltage regulation with simultaneous input power factor correction and control. This approach offers lower cost and higher efficiency by parallel processing of the total power. Flyback converter-I primarily regulates output voltage with fast dynamic response and processes 55% of the power. Flyback converter-II with ac/dc PFC stage regulates input current shaping and PFC, and processes the remaining 45% of the power. This paper presents a design example and circuit analysis for 200 W power supply. A parallel-connected interleaved structure offers smaller passive components, less losses even in continuous conduction inductor current mode, and reduced volt-ampere rating of dc/dc stage converter. TI-DSP, TMS320LF2407, is used for implementation. Simulation and experimental results show the performance improvement.

Low output voltage AC/DC converter with a new scheme of synchronous rectification that complies with IEC 1000-3-2 regulations

The aim of this paper is to study the performance of an AC/DC converter with low output voltage and low input current harmonic content. In order to obtain low output voltages with a high efficiency, synchronous rectification is mandatory. When the output voltage is low, it is very difficult to use self-driven synchronous rectification and additional windings are used to properly drive the metal oxide semiconductor field effect transmitters (MOSFETs). Besides this, IEC 1000-3-2 regulations impose low input current harmonic contents for power levels higher than 75 W. In this paper, a recently proposed synchronous rectification scheme is combined with a modified input current shaper to design a 100 W, 3.3 V AC/DC converter that complies with IEC 1000-3-2 regulations. The efficiency obtained in the prototype was very high for this application (86%) and both the size increase and the cost increase were quite low in comparison with the original topology with no synchronous rectification and no IEC 1000-3-2 compliance.

Design and experimental results of an input-current-shaper based electronic ballast

This paper presents some design issues and experimental results regarding the use of the input current shaper (ICS) technique to implement high power factor electronic ballasts. The ICS is placed between main rectifier and bulk capacitor to increase the conduction angle of the main rectifier diodes up to a minimum value to obtain low current harmonics injected to the mains. Two possibilities to implement ICS-based ballast are considered in this paper: the forward-based ICS and the flyback-based ICS. Experimental results obtained from two 40-W fluorescent lamp ballasts are also presented.

Single current sensor control for single-phase active power factor correction

This paper presents the realization of a boost-type active power factor corrector (APFC) using a single current sensor to sense the inductor current for input current shaping and output voltage regulation. Neither input voltage nor output voltage sensing is needed. The sensed inductor current is used for two main functions. The first one is for comparing with a sawtooth signal in order to shape the input current waveform. The second one is for determining the input and output voltages by processing the rate of change of the inductor current when the main switch is in on and off states, respectively. Compared with conventional APFCs, the proposed technique has several advantages. First, no dissipative voltage divider is required. Second, electrical isolation between the power conversion stage and the control stage can be achieved inherently. Finally, no complicated or sophisticated digital sampling and numerical computations are needed. The applicability and accuracy of the proposed technique have been studied experimentally. Steady-state behavior and large-signal response under output load disturbance are also investigated.

Voltage and current stress reduction in single-stage power factor correction AC/DC converters with bulk capacitor voltage feedback

Single-stage power factor correction (PFC) AC/DC converters integrate a boost-derived input current shaper (ICS) with a flyback or forward DC/DC converter in one single stage. The ICS can be operated in either discontinuous current mode (DCM) or continuous current mode (CCM), while the flyback or forward DC/DC converter is operated in CCM. Almost all single-stage PFC AC/DC converters suffer from high bulk capacitor voltage stress and extra switch current stress. The bulk capacitor voltage feedback with a coupled winding structure is widely used to reduce both the voltage and current stresses in practical single-stage PFC AC/DC converters. This paper presents a detailed analysis of the bulk capacitor voltage feedback, including the relationship between bulk capacitor voltage, input current harmonics, voltage feedback ratio, and load condition. The maximum bulk capacitor voltage appears when the DC/DC converter operates at the boundary between CCM and DCM. This paper also reveals that only the voltage feedback ratio determines the input current harmonics under DCM ICS and CCM DC/DC operation. The theoretical prediction of the bulk capacitor voltage as well as the predicted input harmonic contents is verified experimentally on a 60 W AC/DC converter with universal-line input.

New active input current shapers to allow AC-to-DC converters with asymmetrically driven transformers to comply with the IEC-1000-3-2

Four new topologies of active input current shapers (AICSs) for converters with symmetrically driven transformers (such as half-bridge, full-bridge and push-pull) have been proposed. This paper analyzes the extension of the use of these new AICSs topologies to converters with asymmetrically driven transformers. Using some of these topologies, the size of AICS inductors can be reduced and even integrated in a single magnetic core. As in the case of other converters with AICS circuit, the new topologies allow line current harmonics to be reduced and thereby to comply with the IEC 1000-3-2 specifications, whilst maintaining all the features of standard DC-to-DC converters (e.g., fast transient response). Finally, the proposed topologies have been experimentally tested.

Low-power flyback converter with synchronous rectification for a system with AC power distribution

IEC 1000-3-2 regulations impose a reduced harmonic content on any converter with an input power higher than 75 W. However, if the power architecture of the system is based on small on-board converters, and the total power is higher than 75 W, IEC regulations must be fulfilled although each individual converter need not comply with the regulations. In this paper, one of the different possible solutions is presented. Each on-board converter has an active input current shaper (AICS) in order to reduce the input current harmonic content of each converter and, hence, to comply with IEC 1000-3-2 regulations. Moreover, two different types of AICSs were compared: the conventional one and a new type of AICS based on a full-wave rectifier.

A new AC/DC converter topology with high power factor

A new single-stage, isolated AC/DC converter topology is presented and analysed. The converter is derived by removing the input current shaper inductor from between the diode bridge and the DC/DC converter and integrating its function into the series connection of the isolation transformer leakage inductance and the secondary side charge pump capacitor. A half-bridge is used as the DC/DC converter in order to utilise zero voltage switching (ZVS) and to provide symmetrical excitation for the isolation transformer. It is shown that when charge transfer characteristics of the capacitor charge pump are combined with an appropriate conduction angle, an acceptable power factor can be obtained. A 100W AC/DC converter with 12V DC output was designed and built on the basis of the proposed topology. The prototype converter had an efficiency of 83%, a power factor of 94% and a low-frequency output voltage ripple of 6%.

A topology survey of single-stage power factor corrector with a boost type input-current-shaper

A topological review of the single stage power factor corrected (PFC) rectifiers is presented in this paper. Most reported single-stage PFC rectifiers cascade a boost-type converter with a forward or a flyback DC-DC converter so that input current shaping, isolation, and fast output voltage regulation are performed in one single stage. The cost and performance of single-stage PFC converters depend greatly on how its input current shaper (ICS) and the DC-DC converter are integrated together. For the cascade connected single-stage PFC rectifiers, the energy storage capacitor is found in either series or parallel path of energy flow. The second group appears to represent the main stream. Therefore, the focus of this paper is on the second group. It is found that many of these topologies can be implemented by combining a two-terminal or three-terminal boost ICS cell with DC-DC converter along with an energy storage capacitor in between. A general rule is observed that translates a three-terminal ICS cell to a two-terminal ICS cell using an additional winding from the transformer and vice verse. According to the translation rule, many of the reported single-stage PFC topologies can be viewed as electrically equivalent to one another. Several new PFC converters were derived from some existing topologies using the translation rule.

Input current shaper based on the series connection of a voltage source and a loss-free resistor

A new input current shaper is proposed in this paper. The operating principle is based on the connection of a voltage source and a loss-free resistor (LFR) between the input rectifier and the bulk capacitor in a conventional switching mode power supply with no power-factor correction. Both the voltage source and the LFR are obtained as an additional output from the converter's transformer. This additional output is a forward-type one with one extra inductor. With the final topology, a good tradeoff between capacitor voltage, recycling energy, and harmonic content can be established in order to comply with IEC 1000-3-2 specifications.

Improved active input current shapers for converters with symmetrically driven transformer

This paper deals with the analysis of new implementations of the recently proposed active input current shaper (AICS). Using these implementations, the size of the AICS inductors used in AC-to-DC converters based on "symmetrically driven" DC-to-DC topologies (e.g., half bridge, push-pull, or full bridge) can be reduced and even integrated in only one magnetic core. As in the case of other converters with the AICS, the new implementations allow us to reduce the line current harmonics in order to comply with the IEC 1000-3-2 specifications, maintaining all the features of the standard DC-to-DC converters (e.g., fast transient response). Finally, the four proposed implementations of the AICS have been experimentally tested.

Resonant converter for high-power-factor rectification

Cascade connection of a boost and a resonant converter using a common device pair produces a new topology that combines the input current shaping capabilities of the boost circuit and the soft-switching operation of the resonant converter. The circuit is suitable for high-power-factor rectification. Results are presented from a 100 W prototype.

Design optimization of single-stage single-switch input-current shapers

Design considerations for a single-stage single-switch input-current shaper (S/sup 4/ICS) which combines the boost-like front end with a continuous-conduction-mode DC/DC output stage are provided. A complete design-oriented mathematical model is derived for both discontinuous and continuous conduction modes of operation of the boost inductor. The design procedure is illustrated with the example of a 5-V/20-A universal line-voltage range S/sup 4/ICS forward converter.

A novel single-phase ZCS-PWM high-power-factor boost rectifier

This paper presents a novel single-phase high-power-factor (HPF) pulsewidth-modulated (PWM) boost rectifier featuring soft commutation of the active switches at zero current (ZC). It incorporates the most desirable properties of conventional PWM and soft-switching resonant techniques. The input current shaping is achieved with average current mode control and continuous inductor current mode. This new PWM power converter provides ZC turn on and turn off of the active switches, and it is suitable for high-power applications employing insulated gate bipolar transistors (IGBTs). The principle of operation, the theoretical analysis, a design example and experimental results from a laboratory prototype rated at 1600 W with 400 VDC output voltage are presented. The measured efficiency and the power factor were 96.2% and 0.99%, respectively, with an input current total harmonic distortion (THD) equal to 3.94%, for an input voltage with THD equal to 3.8%, at rated load.

A new high-power-factor three-phase AC-DC converter: analysis, design, and experimentation

This paper proposes a new high-power factor three-phase AC-DC power converter, which is composed of a line interphase transformer (LIT) and two three-phase diode rectifiers, followed by a pulsewidth modulation (PWM) DC-DC boost power converter. The active switch of the boost converter is gated at a constant frequency such that the AC input current is discontinuous. This procedure provides an input current shaping without the third, fifth and seventh harmonics. The currents that flow through the LIT and boost inductors have such a high-switching frequency that ferrite cores with a small size can be utilized. In addition, the output voltage is regulated by PWM to compensate for line voltage variations and load change. Theoretical analysis, design procedure and example, along with experimental results taken from a 6 kW laboratory prototype are given.