Input Power Factor Research Articles

A Natural Bidirectional Isolated Single-Phase AC/DC Converter With Wide Output Voltage Range for Aging Test Application in Electric Vehicle

To ensure the safety and reliability, the aging test of on-board charger (OBC) and dc/dc auxiliary power module (dc/dc-APM) in electric vehicles are indispensable. However, a wide range of battery voltage levels and fast response to power conversion between forward and backward operations are still challenging aspects of the aging test power system. In this article, an improved ac/dc converter is proposed for the aging test application in electric vehicles. The converter consists of two identical topologies, which is made up of three cascaded converters. The first stage is a single-phase ac/dc rectifier, which realizes unity input power factor and power transmission between the ac grid and dc bus. The second stage is the LLC-dc/dc transformer (LLC-DCX) which provides electrical isolation and fixed voltage transfer ratio. Besides, the natural bidirectional power flow can be achieved by the proposed solution. The third stage is a synchronous buck converter (SBC) which guarantees the high dynamic performance and wide range voltage regulation. Experiments based on an 8-kW prototype are conducted to verify the feasibility and effectiveness of the proposed converter and the related control strategies.

간단한 듀티비 제어에 의한 quasi Z-소스 교류 컨버터의 4상한 전압제어 기법

When controlling the output voltage of a quasi-Z-source AC converter, the conventional switching method can only obtain the output voltage of in-phase boost mode and out-of-phase buck boost mode. Therefore, a cascade connection method of an additional quasi-Z-source AC converter was studied to obtain the in-phase buck voltage required in the industrial field. Since this method uses two converters, the hardware is bulky and there are problems such as resonance. In this study, we propose a simple duty ratio control method that can operate in the in-phase buck mode in addition to the in-phase boost mode and the out of phase buck-boost mode without additional quasi Z source AC converter. To verify the validity of this study, PSIM simulations and experiments were performed. As a result, the proposed method can operate not only in the in-phase boost and out of phase buck-boost modes, but also in the in-phase buck mode, and the output voltage is kept constant in the transient state of a sudden load change. Finally, the input power factor and efficiency are more than 90% in most areas when operating in the in-phase mode, but relatively low in the out of phase mode.

Comparative study of control techniques for three phase PWM rectifier

This paper studies and compare the performances of different control strategies of 3-phase active rectifier under different load and frequency conditions. There are three main control approaches to be investigated such as: Voltage Oriented Control (VOC), Direct Power Control (DPC) and Model Predictive Control (MPC). The traditional method VOC has been used widely in practice. Its control principle is available to many different grid-connected converter systems such as electric drive system, renewable energy conversion system. However, the problem of optimal design of the current regulators for the different operating conditions of the system is not an easy problem. The DPC and MPC methods then help to eliminate the disadvantages of the VOC. The MPC method has been now become much interesting since it offers a general solution to a multi-goal optimization problem. In the paper, the system structures and controller parameters are briefly presented. The main evaluation factors of the active rectifier are low input current distortion (THD), a unit input power factor and stable DC output voltage. Three methods are analyzed and verified using MATLAB software and measuring experiment on a real model. The obtained results show that the VOC method achieves stable quality under different load as well as the switching frequency conditions, while the MPC method may achieve good quality with a rather high switching frequency.

A Single-Phase Hybrid Six-Leg AC–DC–AC Multilevel Converter

This article presents a single-phase hybrid six-leg ac-dc-ac multilevel converter. The configuration is composed of a three-leg neutral point clamped converter connected in series with a three-leg two-level converter. The proposed converter provides a sinusoidal input current with unitary input power factor and it feeds the load with a stable ac voltage. The system model, operation principles, and a control strategy are presented and discussed. Additionally, a space-vector puslewidth modulation technique is developed to control the dc-link capacitors, to produce optimal voltage waveforms, and to reduce the switching losses. The converter can generate 9-level and 11-level output voltages when operating with symmetrical and asymmetrical dc-link voltages. Experimental and simulation results are presented to validate the theoretical studies.

CRM Buck converter with high input power factor

CRM Buck converter with high input power factor

Single‐stage pulse frequency controlled AC–AC resonant converter for different material vessel induction cooking applications

SummaryThis paper presents a single‐stage AC–AC resonant converter configuration for different material vessel induction cooking. The proposed configuration features input power factor correction, boost operation, and integrated bridge inverter configuration for multiple loads. In this topology the inverter legs are operated at two different frequencies to power induction cooking loads of steel and aluminum vessels. The induction cooking loads are operated at frequencies closer to their respective resonant frequencies. The load powers are independently controlled by pulse frequency modulation (PFM) technique. The proposed topology eliminates the use of electromechanical switches. The proposed single‐stage AC–AC resonant converter configuration has been tested with two different vessels of steel and aluminum. The simulation and experimental results of the proposed configuration are in good agreement. This topology offers the advantages of low component count, high efficiency, and suitability for different material induction cooking.

Design and Implementation of a Solar Panel Inverter as STATCOM Compensator

A power system suffers from different losses, which can cause tragic consequences. Reactive power presence in the power system increases system losses delivered power quality and distorts the voltage. As a result, many researches are concerned with reactive power compensation. Moreover, reactive power should not be transmitted through a transmission line to a longer distance. Thus, Flexible AC Transmission Systems (FACTS) devices such as static synchronous compensator (STATCOM), static volt-ampere compensator (SVC), and unified power flow controller (UPFC) are utilized to overcome these issues. The necessity of balancing resistive power generation and absorption throughout a power system becomes a big concern in the electrical systems for reactive power compensation. Static synchronous compensator STATCOM is a shunt device used for the generation or absorption of reactive power as desired. STATCOM provides smooth and fast compensation and power factor correction. In this thesis, a solar Static synchronous compensator takes the DC input from the solar panel and inverted utilizing an H-bridge inverter. This topology is used for reactive power compensation and power factor correction at the load side. The simulation was done using MATLAB Simulink simulation tools. The system model was built using a single solar array for DC input and controlled using perturbation and observe method to maximize its power output. The STATCOM model was built using for high power MOSFETs to perform H- bridge inverter. The STATCOM was controlled using a hysteresis band current control using a PI controller to inject the current into the system. A hardware prototype of STATCOM was built and controlled using an Arduino microcontroller. The simulation results have demonstrated the STATCOM model of reactive power compensation and correcting the power factor under different loads of conditions. It also highlighted the proportional relation between reactive power presence and the increased cost of electricity bills. The proposed smart meter of STATCOM gives accurate reading and measurement. Overall, the simulated results showed a satisfactory level of compensation of reactive power and power factor correction. The system contained three significant parts; solar array, H- bridge inverter, and the PI controller. The smart meter circuit was capable of displaying readings regarding input solar voltage, current, and power factor on the LCD screen.

Battery Charger with Bidirectional Power Transmission

The gradual reduction in price of electric batteries contributes to their wider use in autonomous and centralized power supply systems as a backup source of electricity and increase the share of electric vehicles. In the paper the conditions for increasing the efficiency of electric vehicle batteries, in particular in the framework of the concept of V2G (Vehicle to Grid) as a drive for the organization of autonomous power supply systems are analyzed. It is shown that this is possible only with the simple integration of batteries into the system, flexibility, and a wide range of modes that have to be provided by unified charge-discharge devices. Such charging devices have to have such features: a wide range of input and output voltage parameters; correction of the input power factor; the ability to take the maximum power from renewable energy sources; high energy efficiency. A review of possible topologies for a charger with bidirectional power transmission and a bridge converter with soft switching of transistors at zero voltage, which has a high efficiency, galvanic isolation and the ability to correct the shape of the current. The modes of operation of the converter are analyzed and conditions of soft switching is obtained. It is shown that soft switching is valid for current that is not less than minimal one. Efficiency of the converter with soft commutation is compared with a similar converter with rigid commutation of transistors. It is shown that static losses in converter with soft commutation it higher than in the rigid one. So, the proposed converter should be used if the increase in static losses is compensated by the lack of dynamic losses. Additional feature of the converter is that the regulation of the output voltage of the converter with soft switching is carried out according to the law of frequency-pulse modulation with a constant pause duration, where the pause duration is determined by the period of resonant processes of the converter. The model of the converter in Matlab Simulink is built and it is shown that the efficiency of the proposed converter topology is 10-15% higher, which together with the possibility of sinusoidal current with THD ≈ 20% and two-way transmission energy indicates the feasibility of its use as a charger for electric vehicles under the concept of V2G. However, it should be noted that the use of LCL filter creates a phase shift between voltage and current and degrades the THD value. To improve the shape, it is possible to use specialized laws of modulation [or to use modular converters, which allow to obtain a continuous current shape and reduce the volume of the filter.

Non‐isolated high step‐up/step‐down quadratic converter for light‐emitting diode driving

SummaryThis work presents an alternating current–direct current (AC–DC) single‐switch quadratic single‐ended primary inductance converter (SEPIC) for applications involving light‐emitting diodes (LEDs). The proposed topology is basically composed of two cascaded SEPIC stages, where the first one provides input power factor correction (PFC) and the second one allows obtaining power control (PC) for dimming purposes. It is also capable of providing high step‐up or step‐down without requiring the use of extreme duty ratios. A detailed qualitative analysis is derived, from which it is possible to obtain a consistent design procedure. Experimental results from a laboratory prototype are thoroughly discussed aiming at validating the theoretical assumptions.

An Active Power Factor Corrected Power Supply fed Induction Motor Drive by Controlling the Leakage Inductance for Transformer with Soft Switching Strategy

Nowadays the use of electronic equipment finds a progressive development in the modern world. Hence it becomes a mandate to check whether the harmonic content of line current of any electronic device which is connected to the ac supply meets the appropriate standards. This demand is satisfied by implementing the Power Factor Correction (PFC) circuit in order to make the input current to be in sinusoidal in nature and in-phase with the input voltage. Numerous solutions are available to make the line current almost sinusoidal. This paper describes an isolated power factor corrected power supply that utilizes the leakage inductance of the isolation transformer to provide boost inductor functionality. The bulk capacitor is in the isolated part of the power supply allowing for controlled startup without dedicated surge limiting components. A control method based on switch timing and input/output voltage measurements is developed to jointly achieve voltage regulation and input power factor control.

Research on digital long-life time LED driver

LEDs enjoy lifetime up to 10 years, while the lifetime of LED drivers using electrolytic capacitor as power balance component is limited to typically less than 5 years. There is a relatively large deviation between the life of the LED and the life of the power supply. Therefore, it is necessary to eliminate electrolytic capacitors from LED drivers. In this study, a novel digital LED driver without electrolytic capacitor is designed for the problem of the electrolytic capacitors in LED driver is proposed. Compared with traditional LED drivers, the designed driver in this paper not only has the advantage of high input power factor and constant output current, but also because all control functions are realized using software, which provides great flexibility for system modification. The working principle is presented in the article. Finally, the feasibility of the proposed LED driver has been successfully proved by experiment.

A 12-pulse rectifier with passive harmonic reduction based on UIPT in more electric aircrafts

PurposeThe purpose of this paper is to provide a T autotransformer based 12-pulse rectifier with passive harmonic reduction in more electric aircraft applications. The T autotransformer uses only two main windings which result in volume, space, size, weight and cost savings. Also, the proposed unconventional inter-phase transformer (UIPT) with a lower kVA rating (about 2.6% of the load power) compared to the conventional inter-phase transformer results in a more harmonic reduction.Design/methodology/approachTo increase rating and reduce the cost and complexity of a multi-pulse rectifier, it is well known that the pulse number must be increased. In some practical cases, a 12-pulse rectifier (12PR) is suggested as a good solution considering its simple structure and low weight. But the 12PR cannot technically meet the standards of harmonic distortion requirements for some industrial applications, and therefore, they must be used with output filters. In this paper, a 12PR is suggested, which consists of a T autotransformer 12PR and a passive harmonic reduction (PHR) based on the UIPT at direct current (DC) link.FindingsTo show the advantage of this new combination over other solutions, simulation results are used, and then, a prototype is implemented to evaluate and verify the simulation results. The simulation and experimental test results show that the input current total harmonic distortion (THD) of the suggested 12PR with a PHR based on UIPT is less than 5%, which meets the IEEE 519 requirements. Also, it is shown that in comparison with other solutions, it is cost effective, and at the same time, its power factor is near unity, and its rating is 29.92% of the load rating. Therefore, it is obvious that the proposed rectifier is a practical solution for more electric aircrafts.Originality/valueThe contributions of this paper are summarized as follows. The suggested design uses a retrofit T autotransformer, which meets all technical constraints, and in comparison, with other options, has less rating, weight, volume and cost. In the suggested rectifier, a PHR based on UIPT at its dc link of 12PR is used, which has good technical capabilities and lower ratings. In the PHR based on UIPT, an IPT is used, which has an additional secondary winding and four diodes. This solution leads to a reduction in input current THD and conduction losses of diodes. In full load conditions, the input line current THD and power factor are 4% and 0.99, respectively. The THD is less than 5%, which satisfies IEEE-519 and DO-160G requirements.

Single stage AC–DC converter for wireless power transfer operating within wide voltage control range

In the field of e-mobility and automated guided vehicles, studies on a wireless power transfer (WPT) charging system have been conducted recently owing to its convenience, reliability, and positive environmental impact due to the elimination of cords. In this paper, a wireless power transfer charging system using a single-stage AC–DC converter is proposed that can be reduced in size and weight to ensure convenience. The proposed single-stage AC–DC converter can control a wide output voltage (36–54 VDC) within the coupling ranges due to the variable link voltage applied to a WPT resonant circuit through phase-shifted modulation at a fixed switching frequency. In addition, the input power factor (PF) and the total harmonic distortion (THDi) can be improved through the use of the proposed converter. A 1-kW prototype with a 50-mm air gap was fabricated and its effectiveness was validated based on analysis and experimental results.

Low voltage high current modular DC power supply for solid state RF amplifiers

A low voltage, high current, modular 50 V, 700 A dc power supply has been developed to bias 35 number of 500 W, 505.8 MHz solid state RF amplifiers. This power supply incorporates 7 number of 50 V, 100 A ac-dc power modules, operating in parallel to share the load current. This power supply has two unique attributes namely modular hot swappability and active redundancy. Hot swappable feature incorporated in power modules enables isolation of faulty power modules and facilitates their online replacement without affecting the operation of RF amplifiers and remaining power modules. Active redundancy increases reliability of the power supply significantly. Both these features reduce the down time and increase the availability of the overall system significantly. This paper presents comparison of system reliability of this modular dc power supply with other modular dc power supplies of same output voltage and current rating and having different number of power modules. Suitable mathematical expressions for system reliability of these modular dc power supplies have been evaluated. This power supply also has a digital controller for monitoring the status of 35 number of RF amplifiers and 7 number of power modules as well as controls load current sharing among the power modules. This power supply achieves current THD ≤ 6.2%, input power factor ≥ 0.98, output voltage stability ≤ 0.4% and peak to peak output ripple ≤ 0.2% with overall system reliability and availability approaching near 100%.

Research on Control Strategy of Grid-side Converter of Permanent Magnet Direct-drive Wind Turbine

In order to make the permanent magnet direct-drive wind turbines stable and grid-connected operation, a double closed-loop control strategy based on grid voltage-oriented vector and current decoupling is proposed. First, the topology of the grid-side converter of the wind turbine is determined, then the mathematical model of the control strategy is derived, and the parameters of the PI regulator are calculated. Finally, the control strategy is verified by the simulation results. Through the analysis of the experimental results, it is found that the control strategy can achieve the functions of stabilizing the DC bus voltage of the fan and controlling the input power factor, ensuring the stable operation of the fan.

Analysis and Design of Interleaved DCM Buck–Boost Derived Three-Phase PFC Converter for MEA

In more-electric aircraft (MEA), the synchronous generators are connected directly to the turbo engine to develop a constant-voltage variable-frequency (CVVF) ac supply bus. In addition, the MEA has adopted a high-voltage dc bus in its power system to cater to the various categories of load used by aircraft. Therefore, this change in power paradigm has created a requirement for ac-dc power factor correction (PFC) converters to convert CVVF ac to constant dc with high power quality in a reliable manner. In this article, a three-phase interleaved buck-boost-derived PFC converter is operated in discontinuous current conduction mode to realize the inherent unity power factor (UPF) operation for MEA wide range of supply frequency. The benefits of the proposed converter are higher power density, efficiency, and reliability. The advantages of the proposed converter are demonstrated by performing an analytical comparison with the single-cell three-phase buck-boost derived PFC converter and presented the relevant results. The experimental results from a 2.0-kW laboratory concept-proof hardware prototype have been provided to confirm the proposed converter UPF operation for a wide range of supply frequencies. A low input power factor of 0.9996 and a minimum current THD of 2.52% are recorded from the developed prototype.

Input switched closed-loop single phase SEPIC controlled rectifier with improved performances

DC power supply has become the driving source for some essential modern applications. Thereby, DC power conditioning has become a significant issue for engineers. Typically used rectifiers associated with a bridge structure is nonlinear in nature. Thereby, the current at input side of the rectifier contains harmonics, which also flow through the power line. The presence of harmonics causes several interruptions and reduce power quality. In this regard, a new close loop SEPIC controlled rectifier is proposed in this paper. The conventional scheme is arranged with a rectifier connected to a DC-DC converter, which is an open loop system. Consequently, such system cannot regulate voltage at load varying condition. The proposed SEPIC controlled rectifier can regulate voltage under load varying condition for a wide range. Additionally, the performance in terms of total harmonic distortion (THD) of input current and power factor at AC side are also within satisfactory range for the closed loop configuration. The controlled rectifier has four operating phases associated with switching states and input voltage polarity. The close loop configuration also incorporates a current and a voltage loop at the feedback path. The comparative studies have been performed among the proposed closed loop construction, the open-loop structure as well as the conventional construction. The effectiveness of the proposed controlled rectifier is verified in terms of THD and input power factor considering the results obtained from simulation.

An indirect modulation strategy of matrix converters for unbalanced input supply with reduced commutation losses

ABSTRACT This article is focussed on developing a novel hybrid modulation technique for matrix converter. The concept of singular value decomposition (SVD) is utilised to synthesise the intermediate fictitious DC link voltage whereas generalised scalar pulse width modulation (GSPWM) is utilised to generate the target output voltage. SVD provides the required flexibility in selecting the switch states to improve the input power factor. In contrast, GSPWM helps in reducing the switching losses significantly by clamping the output voltage in synchronisation with the peak of the output currents. This proposed phenomenon reduces the switchings at high current which in turn, reduces the losses and improves the efficiency of the converter. The feedforward compensation used at the input side of the converter helps in achieving the balanced output currents for unbalanced input conditions. The simulation and experimental results with loss analysis render validation of the proposed technique.

High Power Density Laboratory Prototype of Single-Phase Solid-State Transformer

Ever since the rise in infiltration of renewable sources into the modern electric grids, the concept of solid-state transformer (SST) has garnered special attention to dynamically control and regulate the power flow while preserving the quality of supply. Though SSTs are capable of catering to a myriad of service demands by customers, their complex multistage architecture, large device count, complexity in control, increased device losses and relatively higher cost remain major bottlenecks for their widespread market penetration. This paper is intended to address the major impediments mentioned above by proposing a simple three-stage, modular architecture for SST with a minimal switch count, high power density and input power factor correction for low power applications. Each stage of SST is equipped with independent, simple and robust controllers contributing to high degree of modularity. A 1 kVA laboratory prototype is built for supplying power to sensitive electric equipment and the results presented in support of the proposed architecture. The developed prototype is shown to have unity power factor at the input, less than 10 percent of the weight and more than thrice the power density relative to the conventional transformer of similar rating.

Torque Ripple Reduction of PMSM With Small Capacitor Drive Systems Based on Combined Control Method

Small capacitor motor drive systems have received increased attention due to higher reliability and longer lifespan. However, small capacitor motor drive systems suffer from poor dynamic performance and larger torque ripple. In this paper, a combined control method is presents to improve the performance of small capacitor motor drive systems. On the one hand, this combined control strategy adopts injected harmonic current to reduce the fluctuation voltage on the DC-link, which provide better conditions for high-performance operation of permanent magnet synchronous motor. To satisfy the harmonic standard of IEC61000-3-2, the guideline of injected harmonic current is deduced according to motor power and the input power factor. On the other hand, an improved repetitive control in parallel with PI control is applied into motor control to effectively suppress motor torque ripple under the condition of the periodic pulsation voltage on the DC-link. In addition, this control method has good dynamic motor performance. Experiments are conducted, and the results verify the feasibility and effectiveness of the combined control strategy.