Fast Output Voltage Regulation Research Articles

A Current-Mode Digital AOT 4-Phase Buck Voltage Regulator

A synthesizable digital adaptive on-time (AOT) 4-phase buck voltage regulator (VR) for digital systems is presented. A current-mode digital AOT controller with the proposed ripple-injection schemes allow a fast and stable output voltage regulation, a fixed switching frequency operation, and phase synchronization for a multiphase VR. The digital AOT controller is implemented in the area of 0.0054 mm2 using digital standard cells in an automated digital-design flow. The proposed VR achieves an 80-mV droop with a recovery time of 80 ns and greater than 85% power-conversion efficiency over a 50 mA to 1.2-A load current range.

Implementation of zero current switch turn-ON based buck-boost-buck type rectifier for low power applications

ABSTRACTA single-stage single-switch AC–DC integrated converter is proposed in this paper, as a tight DC voltage regulator with unity input power factor for the fundamental component of the input current. Proposed converter is formed by the integration of buck-boost configuration with a buck converter operated by a single switch. The buck-boost section of the proposed configuration is operated in current discontinuous conduction mode (DCM) to get unity input power factor at the supply terminals and the buck section is operated up to boundary current conduction mode (BCM). The features acquired by the converter operating in complete discontinuous conduction mode (DCM) are unity input power factor, zero-current turn-ON for the Switch, fast and good DC output voltage regulation with extensive conversion range and low voltage stress on the switch. Additionally, the intermediate capacitor voltage stress is independent of converter load variations and so the switch also is subjected to constant peak voltage stress. A comprehensive study is carried out to obtain the necessary design equations. A design model is implemented using simulation and hardware. The results confirm the performance of the proposed configuration.

Dynamic Improvement of Series–Series Compensated Wireless Power Transfer Systems Using Discrete Sliding Mode Control

This paper presents a discrete sliding mode control (DSMC) scheme for a series-series compensated wireless power transfer (WPT) system to achieve fast maximum energy efficiency (MEE) tracking and output voltage regulation. The power transmitter of the adopted WPT system comprises a dc/ac converter, which incorporates the hill-climbing-search-based phase angle control in achieving minimum input current injection from its dc source, thereby attaining minimum input power operation. The power receiver comprises a buck-boost converter that emulates an optimal load value, following the MEE point determined by the DSMC scheme. With this WPT system, no direct communication means is required between the transmitter and the receiver. Therefore, the implementation cost of this system is potentially lower and annoying communication delays, which deteriorate control performance, are absent. Both the simulation and experiment results show that this WPT system displays better dynamic regulation of the output voltage during MEE tracking when it is controlled by DSMC, as compared to that controlled by the conventional discrete proportional-integral (PI) control. Such an improvement prevents the load from sustaining undesirable overshoot/undershoot during transient states.

Implementation of a low cost, compact single stage power converter with reduced bus voltage stress

Over the recent past, many methodologies to reduce DC bus voltage stress in the single stage single switch power quality converter have been proposed in the literature. The new development resulted in increased efficiency, reduced size and compactness. In this paper, a simple and inexpensive solution with a simple control for the reduction of DC bus voltage stress is proposed. This topology is the integration of discontinuous conduction mode (DCM) boost rectifier for the input current shaping and flyback converter for fast output voltage regulation. With a single active switch, this converter is capable of drawing high quality input current waveform, fast output voltage regulation with reduced bus voltage. No additional component is required to reduce DC bus voltage stress. A design solution and a simple controller is proposed to reduce DC bus voltage stress. As a result, this converter is best suited for universal line application (90-265 V AC). Performance of the converter, design guidelines, small signal analysis, and stability analysis are carried out.

An Efficient Single-Switch Quasi-Active PFC Converter With Continuous Input Current and Low DC-Bus Voltage Stress

This paper proposes a novel single-switch quasi-active power factor correction (PFC) converter based on two flyback dc/dc modules. To achieve a high efficiency, part of the input power is directly transferred to the load by the first dc/dc module. The rest of the input power is stored in the dc-bus capacitor and reprocessed by the second dc/dc module. Together, the dc-bus capacitor and the second dc/dc module also serve as a regenerative snubber. Furthermore, a quasi-active PFC circuit is provided to improve the power factor and to ensure the continuous current mode (CCM) operation of the input inductor without the need for sophisticated feedforward sensing and control mechanism. The quasi-active PFC circuit is driven by a magnetic switch, through the tertiary winding of the transformer of the first flyback module. The input current harmonics of the proposed converter meet the IEC 61000-3-2 (Classes A, C, and D) requirements. The dc-bus capacitor voltage is always less than the input voltage regardless of the load condition and is fairly invariant to large variations of the input voltages. High power factor with CCM operation and fast output voltage regulation have been achieved through a single-loop controller. Operating principles, analysis, and experimental results are presented to verify the effectiveness of the proposed converter.

High Performance Boundary Control of Boost-Derived PFCs: Natural Switching Surface Derivation and Properties

This study presents the application of the natural switching surface (NSS) to control single-phase power factor correctors (PFCs). The proposed boundary control scheme provides tight regulation and enhanced dynamic characteristics. The analysis is performed in the normalized geometrical domain to provide valuable graphical insight and generality. Low-frequency ripple effects are included as part of the converter reference to improve its behavior in steady state and load transient operation. In addition to the complete characterization of the system, a method to obtain fixed-frequency operation is presented by employing discrete-step references. The resulting switching surface (SS) provides fast output voltage regulation and input current dynamics, and low input harmonic distortion, achieving steady state in only a few switching actions under sudden load disturbances. The enhanced qualities of the natural SS are confirmed with simulation and experimental results of a 300 WPFC.

A Single-Switch AC/DC Flyback Converter Using a CCM/DCM Quasi-Active Power Factor Correction Front-End

This paper discusses the major issues that exist in the single-stage ac/dc converters with power factor correction (PFC) and presents a novel converter based on a quasi-active PFC scheme. Two additional windings wound in the transformer of a conventional dc/dc flyback converter are used to drive and achieve continuous current mode operation of an input inductor. In addition, direct energy transfer paths are provided through the additional windings to improve the conversion efficiency and to reduce the dc bus capacitor voltage below 450 V for universal line applications. The proposed converter can be easily designed to comply with IEC 61000-3-2 Class D requirement and to achieve fast output voltage regulation. By properly tuning the converter parameters, a good tradeoff between efficiency, dc bus capacitor voltage stress, and harmonic content can be achieved. Operating principles, analysis, and experimental results of the proposed method are presented.

Dynamical analysis of a novel zero‐voltage‐switching‐PWM DC‐DC half‐bridge converter

In this work, based on the duty‐cycle‐shifted‐PWM half‐bridge converter, a zero‐voltage‐switching‐PWM (ZVS‐PWM) half‐bridge converter is proposed. Both main switches of the proposed converter achieve zero‐voltage‐switching and the converter uses constant‐frequency operation. The small‐signal mathematical model for the ZVS‐PWM half‐bridge converter is derived. Notably, it is verified that the dynamical behavior of the ZVS‐PWM half‐bridge converter is better than that of the conventional PWM half‐bridge converter from a system point of view. The accuracy of theoretical results is verified by simulation and experimental results. A classical controller is then designed to achieve fast output voltage regulation despite variations in line voltage and load resistance.

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.

Dynamic Limits of a Power-Factor Preregulator

Power-factor correction has been one of the hottest topics during the last few years and, hence, many new circuits have appeared. In general, it is assumed that preregulators based on multiplier circuits have poor dynamics and, then, a second stage is needed to improve the output voltage dynamic behavior. The other option is the use of single-stage topologies which have fast output voltage regulation although the input current waveform is not sinusoidal. This work presents an analysis of the dynamic behavior of a conventional power-factor preregulator. The objective is to find the limits of the dynamic characteristics of these circuits when the priority is to improve the output voltage regulation and not the total harmonic distortion or the power factor. A large-signal model is presented and the theoretical results are validated with a prototype.

Flexible and Low Cost Design for a Flyback AC/DC Converter With Harmonic Current Correction

This study presents a new simple flyback ac/dc converter with harmonic current correction and fast output voltage regulation. In the proposed ac/dc converter, an extra winding wound in the transformer provides two key advantages. The size of the bulk inductor used in the conventional boost-based power factor correction cell can be significantly reduced in the proposed converter. The voltage across bulk capacitor can be held under 450V by tuning the transformer winding ratio even though the converter operates in a wide range of input voltages (90 V/spl sim/265V/ac). This new converter complies with IEC 61000-3-2 under the load range of 200 W, and can achieve fast output voltage regulation.

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.

Single-stage single-switch isolated PFC regulator with unity power factor, fast transient response, and low-voltage stress

In this paper, a simple control method is presented for a single-stage single-switch isolated power-factor-correction (PFC) regulator that can simultaneously achieve unity power factor and fast output voltage regulation while keeping the voltage stress of the storage capacitor low. The converter topology comprises essentially a cascade combination of a discontinuous-mode boost converter and a continuous-mode forward converter. The proposed control utilizes variation of both duty cycle and frequency. The role of varying the duty cycle is mainly to regulate the output voltage. Changing the frequency, moreover, can achieve unity power factor as well as low-voltage stress. Basically, the switching frequency is controlled such that it has a time periodic component superposed on top of a static value. While the time periodic component removes the harmonic contents of the input current, the static value is adjusted according to the load condition so as to maintain a sufficiently low-voltage stress across the storage capacitor. The theory is first presented which shows the possibility of meeting all three requirements using a combined duty cycle and frequency control. An experimental prototype circuit is presented to verify the controller's functions.