Pulse width Prediction Control Technique Applied to a Half-Bridge Boost

An AC -DC converter with power factor correction (PFC) function is proposed in this paper. In the proposed converter, the boost PFC stage and the active-clamp DC-DC converter stage are merged into a single converter to reduce the overall cost and improve the power density. An active-clamp DC-DC converter stage can suppress the switch voltage stresses and provide zero-voltage-switching (ZVS) operation of the switches. The boost converter in PFC stage operates in discontinuous conduction mode (DCM) and it provides naturally high power factor. Due to the ZVS operation, the switching losses of the proposed converter are significantly reduced and the efficiency is improved. Steady-state analysis is performed. Simulation results are also provided to verify the effectiveness of the proposed converter.

In this paper, a series-capacitor-based interleaving buck power factor correction (PFC) converter is proposed, the intermediate energy storage capacitance of which is operated at discontinuous capacitor voltage mode (DCVM), and automatic power factor (PF) correction for this converter is obtained. Moreover, the voltage across the series capacitor of the proposed PFC converter is clamped at the input voltage, and thus peak voltage stress existed in the traditional DCVM buck PFC could be relieved. By effectively regulating the charge/discharge time for the series capacitor, ultrahigh step-down conversion ratio of the proposed converter is achieved, the conversion ratio of which is independent of the duty cycle and only related to the switching frequency and circuit parameters. Therefore, high PF can be obtained due to very narrow deadtime of the input current. Meanwhile, the proposed PFC converter can realize the soft turn- on of part power switch and soft turn- off of part power diodes. In addition, comparing with the traditional discontinuous inductor current mode PFC, the input current of the proposed PFC converter is continuous so that the peak value and root-mean-square value of input current can be reduced. The operational principle, performance analysis, and parameter design principle are given in this paper. The analysis results show that the PF and total harmonic distortion are also independent of the duty cycle. Finally, a 220-Vac input, 60 W/15 V output experimental prototype is built to verify the validity of the theoretical analysis.

In this paper, a new single-phase Power Factor Corrector (PFC) based on the Sheppard-Taylor topology is studied. Compared to conventional buck, boost or buck-boost PFCs, this topology allows a better current tracking at the AC side, with a relatively reduced voltage at the DC side. Consequently, the high frequency AC filters required by the buck PFCs are avoided, and the voltage stresses on the boost switches are significantly reduced. Furthermore, the control detuning phenomenon, from which suffer most of the conventional PFCs, especially at very low input voltage, is avoided. This yields major improvements in the source current waveform. Compared to the conventional Sheppard-Taylor converter, this new topology allows lower voltage stresses across the capacitors and larger output voltage range for the same operating area. The converter is integrated as a PFC at the DC-end of a single-phase diode bridge. Pulse-Width-Modulated (PWM) multi-loops control schemes are proposed and developed in order to ensure a unity power factor at the AC-source side and a regulated voltage at the DC-load side. The first one uses the simple and robust hysteretic-based controller, the second one employs a conventional PI regulator, whereas the third one is based on the model nonlinearity compensation approach. The design of the last two control methods is based on the state-space averaged model of the converter. The performance of the different control strategies is evaluated through simulation experiments carried out on a numerical version of the converter. The implemented model of the converter is obtained by using the switching function technique. The control system is tested under both rated and disturbed operating conditions. The system performance is evaluated in terms of source current Total Harmonic Distortion (THD), input power factor, DC voltage stabilization, and regulation following load variations.

Single-phase ac-dc Power Factor Correction (PFC) rectifiers have attracted considerable attention in recent years due to the adoption of increasingly stringent power quality regulations. In this paper a nonlinear model predictive controller design for a single-phase Flyback PFC rectifier is presented. After approximation of the tracking error in the receding horizon by its Taylor-series expansion to a specified order, an analytic solution to the model predictive control (MPC) is developed and a closed-loop nonlinear predictive controller is introduced. The main advantage of this digital control method is that unity power factor can be achieved over wide input voltage, load current range and on high dynamics directly depend on the processing speed of microprocessor. This method is applied to a flyback PFC rectifier, can improve the voltage control dynamics. Simulation results show that flyback PFC rectifier with NMPC provides better and more accurate performance in both steady states and transient compared to linear control methods.

A novel three-phase major circuit topology is proposed in this paper and its circuit design is also given. Its characteristic is that specific PFC integrated circuit is not applied in this AC-DC converter, there are less circuit components and its power factor is very high. Moreover, its operation principle and power factor correction principle are discussed and analyzed in detail. Its simulation results operating in different duties using MATLAB/SIMULINK are also given. The rationality and correctness of its circuit topology and principle are explained and verified by theory analysis and simulation results.

A comparison of fuzzy self‐tuning (FST), sliding mode control (SMC) and conventional proportional–integral (PI) control methods is performed under unbalanced grid conditions using a bridgeless power factor correction (PFC) converter. The bridgeless PFC converter operates the correction of AC line current to obtain a DC output voltage without full bridge rectifier based on these control methods. These control methods generate the duty cycles to provide higher unity power factor and lower total harmonic distortion of input current, even if AC line voltage is distorted. This study focuses on the performance analysis of FST and SMC methods adaptation to the input current for the bridgeless PFC converter and comparing with the conventional PI controller. Although the SMC method is only used in the current control loop, the FST method is used in both current and voltage control loops for eliminating harmonics of input current and regulating of output voltage. The performance of control methods is evaluated with a TMS320F2812 digital signal processor. The simulation and experimental results are compatible with the limits for harmonic current emissions, IEC 61000‐3‐2 and show that the FST and SMC are better than the conventional PI control method and FST is superior to the SMC.

In this paper, a single-stage bidirectional isolated direct-matrix-based AC-DC converter with a power factor correction is proposed. This AC-DC converter can control not only the DC output voltage or current, but also the AC grid current with a single conversion stage, which helps to achieve a higher power density with a lower complexity. A modulation scheme that can achieve a zero voltage switching (ZVS) or zero current switching (ZCS) operation in all switches is developed. Hence, the switching frequency of the converter can be increased higher, leading to the smaller passive components. The proportional-resonant (PR) controller is utilized to achieve the unity power factor and low total harmonic distortion (THD) current. The proposed topology has been verified by simulation results for a 3.3 kW system.

The purpose of this paper is to present a novel digital control boundary current mode ac-dc converter. The ac-dc converter is widely used as power factor correction. The ac-dc converter that operates in a boundary current mode has the some advantages. It has capability to achieve low current distortion. The unity power factor is theoretically obtained by the boundary current mode control. In the proposed method, nonlinear equations is solved using Newton's method to predict the zero-cross point of the inductor current.

AC/DC converters used in electric vehicles generally consist of two stages: an input power factor correction (PFC) boost AC/DC stage that converts input AC voltage to an intermediate DC voltage and reduces input current harmonics injected to the grid, and a DC/DC converter that provides high-frequency galvanic isolation. Since there is a low-frequency ripple (second harmonic of the input ac line frequency) in the output voltage of the PFC AC/DC boost converter, the voltage loop in the conventional control system typically has a very low bandwidth to avoid distorting the input current waveform. This causes the conventional PFC controller to have slow dynamics against load variations. This paper presents a new control approach that regulates the input power of the converter instead of the output voltage by using an optimal nonlinear control approach based on the Control-Lyapunov Function (CFL). In this paper, it is shown that the proposed controller is able to eliminate the low bandwidth voltage control loop in the conventional PFC controller, thus allowing the front-end AC/DC boost PFC converter to operate with faster dynamic response than with the conventional controller approach. Experimental results from a 3 kW AC/DC converter are presented in the paper to validate the proposed control method and its superior performance.

This paper proposes a digital control system, based on the Steinmetz method and instantaneous power theory, applied to the static var compensator to compensate the unbalance between the phases and the power factor of loads. The proposal incorporates an additional digital filtering system for elimination of harmonic components and for the extraction of positive-sequence voltage. The experimental results demonstrated good precision in the compensation of the unbalance and in the correction of the power factor. The experimental tests indicate reduction of the unbalance factor of 44.9% to 3.3% and correction of the fundamental power factor to the unit.

The quality of power is degrading day by day due to heavy use of non-linear loads. Power factor is a measure of effectiveness of electricity usage. AC-DC converters are modified to operate as power factor correction circuit In this paper, a novel control algorithm is developed to provide power factor correction(PFC) of air condition loads so as to optimize its operation. Novel algorithm also aims at controlling the output voltage and speed of compressor motor. Proposed design provides a simple, compact and low cost converter with low voltage stresses. This paper presents the evaluation of a constant frequency active clamped flyback converter for PFC. The work is simulated and analyzed in MATLAB.

A new single-stage high frequency-link three-phase <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LLC$</tex-math></inline-formula> ac–dc converter is proposed in this article. The proposed converter is featured by a boost full-bridge topology-based phase module with power factor correction (PFC) for the three-phase utility frequency ac to single-phase high-frequency ac conversion without a smoothed dc link, which brings the simplicity, cost-effectiveness, excellent modularity, and high efficiency into the power supply. The soft switching commutation can achieve over the wide range of load power with the assist of magnetizing current of a high frequency transformer in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LLC$</tex-math></inline-formula> topology. The load power and voltage can be regulated by pulse frequency modulation and phase-shift pulsewidth-modulation depending on the load conditions. The effectiveness of the proposed converter is investigated by simulation and experiment of a 2 kW–50 kHz preliminary prototype, thereby the single-stage frequency conversion, PFC and zero voltage soft-switching are revealed from a practical point of view.

Front end PFC (power factor correction) boost ac-dc converter is an intrinsic part of applications like telecom servers, electric vehicle (EV) charging, and microgrids. In this paper a bridgeless PFC boost rectifier with two dc/dc boost circuits topology is employed to convert universal ac input to a fixed and regulated output dc voltage. High efficiency and power density are key figure-of-merits of boost PFC ac-dc converters. In this converter the conduction losses are reduced owing to the bridgeless topology and the boost diode reverse recovery is eliminated using MOSFETs for synchronous rectification. The converter operates in continuous conduction mode (CCM), at a switching frequency of 500 kHz. At high switching frequency and at CCM, soft-switching is necessary, therefore a passive auxiliary circuit is used to achieve zero voltage switching (ZVS). In order to increase the power density, the boost and the auxiliary inductors are magnetically coupled with a very low coupling coefficient. This coupling reduces the volume of the magnetics, although there is some loss due to the additional circulating current resulting from the coupling, however this loss is not that significant. Although passive auxiliary circuit adds more components, however at 500 kHz switching frequency these passive components do not occupy significant space. The soft-switching improves the efficiency and reduces EMI noise and cooling requirements. The detailed analysis, design and simulation results using PSIM are provided to validate the theoretical claims.

The traditional AC-DC power switching supplies often use the diode rectifier, due to the presence of the large filter capacitor and the switching devices, the power factor of the circuit is usually low, and the harmonic pollution in the grid side is serious. To solve the problem, a method that cascades a PFC (power factor correction) circuit is generally used, however, this increases the circuit stages, which not only reduces the circuit efficiency, but also causes the circuit structure and the control strategy more complex. In this paper, we study a kind of LLC resonant AC-DC converter circuit with PFC function based on a double inductor structure circuit, which can realize the single-stage power conversion and improve the power transmission efficiency. The characteristics of the circuit can achieve the conventional LLC resonant conversion, which ensures the switching devices working in soft-switching mode. And the double inductor structure PFC circuit, using interleaving methods, can better overcome the harmonic distortion problem in the input current in the traditional single-stage PFC AC-DC circuit. In this paper, the theoretical analysis and simulation of the circuit topology are given out, and the experimental results verify the correctness of the theoretical analysis, it also proves that the circuit can both have a good PFC and a AC-DC transform function.

In the last decade, the amount of electronic equipment connected to the AC line has been increased; this equipment presents low values of power factor (PF) and high total harmonic distortion (THD) due to their nonlinear behavior. The personal computer (PC) is one piece of electronic equipment that has these problems, the main reason being because it was decided to develop a switching mode power supply (SMPS), for the PC, with power factor correction (PFC). In this paper, the experimental results of the SMPS prototype for PC applications, which includes a PFC feature, are presented. Analysis of the design compromises that must be kept in mind in order to develop a SMPS with PFC has been included. This analysis evaluates the compromises that must be considered when in the design of a SMPS with PFC, we try to obtain the best power factor (PF), total harmonic distortion (THD) and construction cost.