Studies of a novel AC-DC converter with three-phase power factor correction (PFC)

This paper proposes a three-phase power factor correction (PFC) for a three-phase induction motor (IM) drive under normal and abnormal supply voltage conditions. A new technique of PFC based on a positive sequence components method is introduced. The PFC circuit uses a SEPIC converter with a single switch, which needs only one control signal. The PFC control method with the proposed technique provides nearly sinusoidal supply currents maintaining a high power factor under different supply voltage conditions. Furthermore, the PFC method maintains DC bus voltage at the desired value. The regulated DC voltage feeds a four-switch inverter of the three-phase IM drive system. Mathematical analysis of the equivalent circuits based on operation modes of the SEPIC converter is introduced. The performance of the proposed technique is evaluated under ideal and non-ideal supply voltage conditions. The results are analyzed in terms of reduction in the THD of supply currents and improvement of power factor. System validation performed in simulation and experiment has shown the effectiveness of the proposed system under different supply voltage conditions.

Present day standards and applications require power electronic ac- dc converters that can operate over a wide range of load variations with approximately unity power factor, controlled dc bus voltage, low input current distortion, and a simple controller. Power factor correction (PFC) techniques can be a practical solution to unidirectional rectifiers since they reduce the number of devices, and improve the efficiency and power system quality as well. This paper presents a new topology of a modular three-phase AC-DC converter. The presented PFC converter can produce a controlled dc output voltage, near-unity power factor, and high efficiency. By operating in the continuous conduction mode (CCM) with an active approach which is one class of high-quality three-phase rectification, the required features are achieved. The performance of the topological structure of the presented converter is discussed and investigated under various modes of operation to identifies their merits and limitations. Extensive simulation is carried out using PSIM software to validate the explained function.

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.

The buck-boost power factor corrected (PFC) converter has the wide range of the dc output voltage. A new non-isolated three-phase hard-switching buck-boost PFC converter and a new non-isolated three-phase soft-switching buck-boost PFC converter are proposed. Their structures are very compact and the low cost is achieved by removing the three-phase transformer. They are operated in the discontinuous current mode (DCM) and controlled by a new control method to achieve the high power factor. The new control method based on the PWM technique is presented in this paper.

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.

In more electric aircraft (MEA), three-phase power factor correction (PFC) rectifiers of several kilowatts are required. In this paper, a three-phase buck–boost derived PFC converter with three switches and with input inductors connected in delta configuration for use in MEA is presented. The proposed converter is operated in a discontinuous conduction mode to achieve PFC at ac input. This avoids the inner current control loop which further eliminates the current sensors. It requires only one output voltage sensor unlike five sensors in conventional PFC converter for its control implementation. This makes the system cost effective, more reliable, and robust. A simple voltage control loop is used to generate the gate signals. The steady state operation of the converter and detailed design calculations are presented. For each power component, the analytical expressions for calculating the average and rms current ratings are derived to facilitate the converter design. The small-signal model of the converter is presented to aid the controller design. The experimental results from a 2 kW laboratory prototype are presented to confirm the operation of the proposed converter. An input power factor of 0.999, an input current total harmonic distortion of as low as 2.76%, and a high conversion efficiency of 96% are achieved from the prototype.

The pulse width prediction control technique has been widely used in AC-DC converters with power factor correction in boost topology, where satisfactory results have been reported without the need to use classic control laws. However, this technique has not been explored for other types of ACDC converters with power factor correction. In this work, the use of this technique is proposed in an AC-DC converter with power factor correction in a half-bridge boost topology. This topology presents high efficiency because it uses the least number of semiconductors compared to other topologies. In this technique the duty cycle is predicted by processing the average values of state and input variables of the converter in half bridge boost topology, using only four multiplications and five additions, which implies less complexity in its implementation. For its validation simulations were performed using MATLAB R simulink, where it was possible to observe values of power factor and THD comparable with other control methods such as non-linear carrier control, and conventional analog control, both reported in the literature.

A novel three-phase full-bridge power factor corrector is presented in this paper. The corrector operates in discontinuous conduction mode (DCM), the peak of input current follows the input voltage automatically. It can achieve zero-voltage-switching (ZVS) for the leading-leg switches and zero-current-switching (ZCS) for the lagging-leg switches without adding any auxiliary device. Due to the adoption of high frequency transformer, the electrical isolation between input and output sides and output voltage regulation could be achieved. The corrector is very suitable for charging systems. It can reduce the voltage stress of the switches of the DC/DC converters used in the later stage as well as achieve a high power factor (PF) in the input side. Some introduction and analysis about the corrector has been given. Finally, the analysis on this corrector has been verified through simulation and experiment.

In this paper, a modified SEPIC converter is presented to function as a power factor corrector (PFC). The modified SEPIC-type PFC not only can achieve unity power factor but reduce dc-link voltage to release component stresses. Therefore, it is suitable for high line-voltage applications. A soft-switching cell composed of an active switch and an inductor-capacitor resonant circuit is embedded into the PFC to obtain zero-voltage switching (ZVS) feature. As a result, the efficiency of the converter is improved significantly. Operation principles are discussed in detail and conceptual key waveforms are also shown in this paper. A prototype is designed, analyzed and implemented. The simulation results and practical measurements have verified the feasibility of the proposed modified soft-switching SEPIC converter.

Hızlı DA şarj için elektrikli araç şarj istasyonu, araç dışında AA-DA dönüşümü gerçekleştirir. Son yıllarda, üç fazlı AA-DA güç faktörü düzelten (GFD) dönüştürücüler hızlı şarj cihazı ile birlikte ele alınmaktadır. Bu dönüştürücüler, tek yönlü ve çift yönlü güç akışı yapısı kullanılarak geliştirilmiştir. Bu çalışmada, çift yönlü güç akışı sağlayan üç fazlı AA-DA GFD dönüştürücü topolojileri performans açısından değerlendirilmiştir. Amaç, elektrikli araç hızlı şarjı için en yeni üç fazlı çift yönlü çok seviyeli AA-DA GFD dönüştürücü teknolojisini sunmaktır. Bu makale, elektrikli araçlar için hızlı şarj altyapısıyla ilgilenen araştırmacılar için kapsamlı ve pratik bir inceleme sunmaktadır.

The operating principle of the novel three-phase parallel power factor correction is presented. The corresponding hysteresis current control strategy is adopted. The merits can be verified by the simulation results. Compared with the normal PFC, the novel three-phase parallel power factor correction is easy to control and only 20% of the energy flows through the full-controlled devices.

This paper presents a systematic and comprehensive approach for differential mode (DM) electromagnetic interference (EMI) filter design in a three-phase boost-type power factor correction (PFC) rectifier. Since the DM EMI filter forms a significant portion of the overall filter as well as converter volume, the reduction of DM filter component size is kept as a major objective in the filter design process in order to improve the power density. In addition to the objectives of volume optimization and conducted emission attenuation requirement to comply with the EMI standard, the filter design process also ensures a near-unity power factor operation with the optimal set of EMI filter parameters. To accomplish this, the paper analyzes the effect of EMI filter component selection on the overall lower order (1-100 kHz) frequency response, which is important for evaluating the dynamic response and stability. The results from the proposed design approach are validated through simulation, the DM Bode plot, and frequency response of the input current with and without EMI filter. As a proof-of-concept verification, the proposed EMI filter is implemented in a 4-kW three-phase boost-PFC prototype, which demonstrates minimal phase displacement (<;5°) of the input current.

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.