Single-phase Diode Rectifier Research Articles

Implementation of Power Factor Correction using Asynchronous Boost Converter on Single Phase Full-Bridge Diode

In various industrial applications, the use of a power supply that uses a conventional diode single-phase rectifier topology results in high harmonic values in the electricity distribution system. One of the real impacts of this harmonic value is the heating of the electric power system equipment and power losses. High rms current values due to harmonics often cause problems in protection settings in addition to efficiency problems. The percentage value between the total harmonic component and the fundamental component is called THD (Total Harmonic Distortions). Therefore, in this study an asynchronous dc-dc boost converter is connected to the output side of a single-phase diode rectifier which is capable of improving power factor and low harmonics. So that a THD value of less than 15%, PF (Power Factor) = 0.92-1 and a sinusoidal input current can be obtained. The implementation results show that the PFC (Power Factor Correction) method can work well on single-phase diode rectifiers.

Power Factor Correction Using a Series Active Filter

Abstract: Power factor correction (PFC) for single-phase diode rectifiers utilising a series active filter is demonstrated in this project at a minimal cost. When compared to the typical PFC, the suggested PFC has reduced power device ratings requirements, which results in cheaper costs and improved efficiency. It can also eliminate the requirement for a large inductor in the typical PFC, making it more compact. This study examines the proposed PFC's topology, operating principle, and application concerns. The control approach and simulation results are presented in detail. Prototypes of 1-kW are made and the experimental findings are shown to verify the theoretical analysis. Index Terms: Harmonic resonance, hybrid active filter, industrial power system.

A Multiphase AC–DC Converter With Improved Power Quality for EV Charging Station

This work presents a multiphase ac–dc converter-based electric vehicle (EV) charging station that is designed to meet IEEE-519 power-quality (PQ) standard. The proposed EV charging station draws current from the utility grid at low total harmonic distortion (THD) and high power factor (PF), without using PF corrector and active/passive filter circuits. This study evaluates an 18-phase ac–dc converter for an EV charging station, which consists of three single-phase multiwinding transformers (MWTs) and diode rectifiers. MWTs are connected to enable direct conversion of a three-phase utility supply into an 18-phase power supply that reduces the measured THD in the input line current. The ac–dc conversion stage of the proposed EV charging station is found to be reliable and operates at line-frequency, without the need for high-frequency active switches. For charging an EV in constant current (CC) and constant voltage (CV) mode, a multiphase (interleaved) dc–dc converter is used. MATLAB/Simulink environment is used to evaluate the performance of the proposed EV charging station in terms of THD and PF. The results are validated through an on-the-bench prototype hardware setup of the proposed EV charging station.

Comparative Study on Thyristor and Rectifier Circuit Based DC Motor Control with Improved Power Factor and Total Harmonic Distortion

DC motor is used in many industrial applications. Because it has versatile control characteristics. With the increasing use of power semiconductor units, the speed control of the DC motor is increasingly getting sophisticated and precise. The DC motor can control by various methods, which is as field control, armature voltage control, armature resistance control. The speed of the DC motor is controlled by controlling the armature voltage. Armature voltage is controlled using different single-phase AC/DC converter. Half converter, semi converter, full converter, and dual converter are some of the thyristor-based circuits, which are used for speed control of DC motor. But using power electronics devices causes power factor and total harmonics distortion problem. Different types of Rectifier circuit with filter capacitor is used to reduce the problem of power factor and total harmonics distortion like Conventional single-phase diode rectifier with filter capacitor, single-phase diode rectifier with LC filter, single-phase diode rectifier circuit with series input resonant filter, Single phase diode rectifier circuit with improved parallel input resonant filter. In this paper, we do a comparative analysis of controlling DC motor with improved PF and THD.

Harmonic damping characteristics of single-phase full-bridge rectifier based loads

With the rapid development of power electronic technology, many linear single-phase loads in low voltage systems are replaced by those equipped with a single-phase diode rectifier. Therefore, most of single-phase loads become harmonic producers due to their nonlinear characteristics. The nonlinear loads may have different damping characteristics at harmonic frequencies, which would bring potential power quality problems. This paper studies the harmonic damping characteristics of such nonlinear loads. The harmonic damping index is defined to quantify the damping effect of nonlinear loads at harmonic frequencies by analyzing the harmonic model. Then, the harmonic damping index at different harmonic frequencies is compared through simulations and experiments. The results show that the nonlinear load has a constant damping effect at the fundamental frequency, but stronger damping at harmonic frequencies. The harmonic damping of such nonlinear loads varies with the harmonic phase angle of supply voltage, and becomes stronger with the increase of the harmonic order. It implies that this type of nonlinear loads may be beneficial to the suppression of harmonic resonance.

Direct Active and Reactive Power Control of Three-Phase Inverter for AC Motor Drives With Small DC-Link Capacitors Fed by Single-Phase Diode Rectifier

This paper proposes a power controller used for three-phase inverters with small dc-link capacitors fed by a single-phase diode rectifier. The effect of the reactive power was investigated based on a power flow analysis between a dc-link and three-phase inverter. These results enable the development of a direct active/reactive power controller in discrete time instead of adopting a classical proportional-integral (PI)-type current regulator, which directly leverages the total power flow of the system. A suitable reactive power selection method was presented to improve the overall system efficiency. The command voltage vector at each discrete time step can be simply and intuitively determined by an inverter power without requiring motor current-regulating PI gains and additional control functions. The proposed controller regulates an average motor velocity/airgap torque while simultaneously shaping a grid-side current with a high power factor and low harmonics to meet IEC61000-3-2 requirements. The proposed structure can be applied to three-phase inverters for a broad family of ac motors, such as induction and permanent magnet synchronous motors.

High Voltage Gain Impedance-Source Indirect Matrix Converter

This paper proposes a high voltage gain indirect matrix converter to eliminate the voltage degradation problems in AC drive. The proposed converter consists of modified LC-C-LC single-phase bridge rectifier combined with a three-phase Z-source inverter. The combined design of LC-C-LC filter with the single-phase diode rectifier is able to step up DC rectified voltage greater than peak AC input voltage without the requirement to active switching devices. In addition, it can also reduce the input current harmonics, improve input power factor and reduce reactive power consuming from AC supply. To further increase boost capability of the proposed converter and eliminate the voltage degradation problems, the LC-C-LC rectifier is combined with a Z-source inverter. This combination not only increase the converter’s voltage gain but also reduce the reactive power and converter’s size through using small LC-C-LC and Z-source parameters which consequently increase the system’s efficiency. A new Modified Space Vector Pulse Width Modulation (MSVPWM) method has been proposed in order to dominate the shoot-through duty ratio of Z-source inverter. This method results in reducing the level of harmonic for the output current and increasing the dynamic range of the shoot-through duration. The overall drive system has been simulated and analyzed using a hybrid simulation between OrCAD/PSpice and Matlab/Simulink environments through using SLPS integration platform.

Discontinuous Grid Current Control of Motor Drive System With Single-Phase Diode Rectifier and Small DC-Link Capacitor

In this paper, a control method for motor drive system without electrolytic capacitor is proposed. Since dc-link capacitor of this motor drive is about 1% of the conventional one, it can satisfy the grid current regulation of IEC61000-3-2 without bulky filter circuits by directly controlling the electric output power of the inverter. However, dc-link voltage of this drive fluctuates as the rectified grid voltage. It causes higher motor current, especially at the low dc-link voltage area, and severely harms the drive efficiency. To solve this problem, proposed method keeps the dc-link voltage higher than certain limit while controlling the output power. It can improve the efficiency of the drive by lowering the d-axis current at low dc-link voltage area, with satisfying the regulation with small grid current harmonics. The proposed method includes the motor current reference generation for the limited dc-link voltage and selection of the limitation value. The improved performance of the proposed method was verified by the experimental results.

Single-Phase Grid-Connected Motor Drive System With DC-Link Shunt Compensator and Small DC-Link Capacitor

The single-phase diode rectifier system with small dc-link capacitor shows wide diode conduction time and it improves the grid current harmonics. By shaping the output power, the system meets the grid current harmonics regulation without any power factor corrector or grid filter inductor. However, the system has torque ripple and suffers efficiency degradation due to the insufficient dc-link voltage. To solve this problem, this paper proposes the dc-link shunt compensator (DSC) for small dc-link capacitor systems. DSC is located on dc-node in parallel and operates as voltage source, improving the system performances. This circuit helps the grid current-shaping control during grid-connection time, and reduces the flux-weakening current by supplying the energy to the motor during grid-disconnection time. This paper presents a power control method and the design guideline of DSC. The feasibility of DSC is verified by simulation and experimental results.

スイッチング素子を用いない単相高力率ダイオード整流器

Single-phase diode rectifiers offer simple topology, low high-frequency noise, high reliability, and high environmental durability. However, diode rectifiers produce undesirable lower order harmonics in the input current. To overcome the problem, the authors present a single-phase power factor correction diode rectifier without active switching devices. To illustrate the validity of the rectifier, experimental results obtained from a 1.5kW, 200V system are shown.

MODIFICATIONS OF DIODE RECTIFIER CIRCUITS FOR CONTINUOUS INSULATION MEASUREMENT IN LIVE AC IT NETWORKS

Purpose. In the paper there are described few systems of insulation resistance continuous measurement using an imposed DC test signal delivered by diode rectifiers. Drawbacks of this technique are pointed out and ways of these shortcomings removal are proposed. Methodology. An improved version of measuring circuit based on a single-phase diode rectifier is presented. Application of logometric measuring devices is suggested. Results. A new insulation resistance continuous measuring system is insensitive to network voltages variation and asymmetry. Modified circuit enables also implementation of a simple device for alarming the monitored network’s insulation deterioration and/or earth-fault protection. Originality. Formulas describing performance of diode rectifiers under asymmetrical supply have not been available so far. Both innovations (i.e. single-phase diode rectifier and logometric meter) have not been applied widely for implementation of continuous insulation monitoring in live AC IT networks. Practical value. Use of both innovations will allow to eliminate unrequired dependence of measurement results on variable network voltages as well as their possible asymmetry. Exploitation of diode rectifier circuits for earth fault location is also possible. References 6, figures 9.

Analytical frequency modeling of a diode rectifier: formulation for SQP solving versus formulation for Newton-Raphson solving

Purpose Static converters generate current harmonics in grids. Numerous studies on analytical frequency models of converters are often required to carry out their harmonic modeling in the context of sizing by optimization. Some formulations are proposed to solve such models. Each formulation has its own advantages and drawbacks. The paper mainly focuses on two formulations: the first to be solved by Sequential Quadratic Programming (SQP) and the second to be solved by Newton-Raphson (NR). In this way, the paper presents the performances of each formulation and compares the results of both formulations for the modeling of a single-phase diode rectifier. Design/methodology/approach The paper aims to compare SQP formulation and NR formulation, and to propose the ways to improve their convergence. In the modeling, by using an explicit formulation of the state variables combined to a numerical method, equations are defined to reduce, as far as possible, the number of unknowns. Findings The difficulty is to find the good operating mode of the static converter. So, outside the equations and the constraints, the paper proposes to use the eigenvalues of the state space matrixes to initialize the duration of every configuration and to consider the operating symmetries of the static converter that allow to reduce the research area and also the variables calculated. Research limitations/implications The number of the conducting phase per half period is a priori, as the operating mode. Originality/value The modeling is based on the use of linear components, ideal switches and the static converter operates in steady-state. The main difficulties are to formulate the equations representing the non-controlled switching of semiconductors, and to solve them.

Design and implementation of a linear quadratic regulator controlled active power conditioner for effective source utilisation and voltage regulation in low‐power wind energy conversion systems

Power electronic converters play a major role in wind energy conversion systems (WECS). A typical variable speed WECS includes wind turbine, permanent magnet synchronous generator (PMSG) and power conditioners. In this study, a three-phase modular boost converter supplied from a PMSG and controlled using a linear quadratic regulator (LQR) is proposed for battery charging applications. Each phase of PMSG is connected to a single phase diode rectifier and a DC–DC boost converter. All boost converters have a common output capacitor and load. The proportional–integral-based voltage controller provides voltage regulation on the DC side. A fixed frequency LQR-based current controller applied for the individual phases provides a better three-phase source utilisation. The instantaneous pq theory is adopted for the reference current calculation. Extensive simulation studies based on the models developed using MATLAB/SIMULINK reveal that the proposed system performs satisfactorily for step variations in wind speed and load. The performance of the low power prototype developed and controlled using a dSPACE 1104 digital signal processor shows good output voltage regulation and better source utilisation for wide variations in load.

Direct Power Control of a Three-Phase Inverter for Grid Input Current Shaping of a Single-Phase Diode Rectifier With a Small DC-Link Capacitor

This paper describes motor drive system fed by a single-phase diode rectifier without power factor correction (PFC) circuit or the input filter. The system considered in this paper consists of a single-phase diode rectifier, a three-phase inverter, and a small dc-link capacitor. Since dc-link capacitance of the proposed system is few microfarads, the shape of the grid input current is directly affected by electrical output power of the inverter. Using this aspect, two goals of the drive system, controlling torque of the motor and suppressing the grid input current harmonics, can be simultaneously achieved by controlling the output power of the inverter. The proposed method includes the motor current reference generation and the direct output power regulation by modifying the output voltage reference. With the proposed method, the harmonic components of the grid input current can be reduced under the limits of the regulation IEC61000-3-2, lower than those in the conventional method. Also, the cost and size of the inverter system can be significantly reduced by removing electrolytic dc-link capacitor and input filter from the system. The performance of the proposed shaping method was validated by the experimental results using the motor drive system with a 5μF film capacitor at dc link.

HARMONIC MITIGATION FOR POWER QUALITY IMPROVEMENT

In every industries non-linear load such as single-phase diode rectifier, converters, inverters, low voltage power supplies, SMPS, personal computers etc are exists. In every three-phase system the lowest and significant order of harmonic will be 5 th harmonic after the fundamental. This harmonics incurs losses in the form of heat dissipation and also contribute to eddy currents and core losses. This extra heat have significant impact in reducing the operating life of electrical instrument especially transformer insulation. This paper provides information on harmonic mitigation techniques for power quality improvement.

High Power Factor Hybrid Rectifier

This paper presents the analysis of a new single-phase hybrid rectifier with high power factor (PF) and low harmonic distortion current. The proposed rectifier structure is composed of an ordinary single-phase diode rectifier with parallel connection of a switched converter. It is outlined that the switched converter is capable of shaping the input line current waveform, assuring high PF and low total harmonic distortion (THD). The power rating of the switched converter is less than 50% of the total output power; assuring reliability in the proposed hybrid rectifier. A pulse width modulation (PWM) control strategy was developed, imposing quasi-sinusoidal line input current waveform and limiting the switched converter power contribution. It was found that the line input current harmonic spectrum is in accordance with the harmonic limits imposed by IEC61000-3-4. The principle of operation, the mathematical analysis, and simulated results are also presented in the paper. http://dx.doi.org/10.4314/njt.v33i4.2

High-Power-Factor Single-Phase Diode Rectifier Driven by Repetitively Controlled IPM Motor

This paper proposes a new power factor correction method using an inverter-driven interior permanent magnet (IPM) motor. The proposed system realizes the high power factor of a single-phase diode rectifier by using a three-phase pulsewidth modulation inverter and an IPM motor. The proposed converter consists of a single-phase diode rectifier, a small film capacitor at the dc link (14 μF and 0.33 J/kVA), a three-phase voltage-source inverter, and an IPM motor. In the proposed system, the inverter has the following two functions: 1) It regulates the velocity of the IPM motor, and 2) it controls the source-side-current waveform. In order to obtain a unity-power-factor operation at the source side, we propose and implement a new control method that regulates the inverter output power. The proposed control method is that the inverter regulates <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> - <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis current synchronous with input voltage. An inverter-output-power controller is positioned between a speed controller and a <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">q</i> -axis current controller. The inverter output power is regulated by a proportional-integral and repetitive controller. The maximum power factor obtained by the proposed method is 98.7% at the rated-load conditions. The superior performance of the proposed system is demonstrated by experimental results.

Novel schemes used for estimation of power system harmonics and their elimination in a three-phase distribution system

Estimation of power system harmonics and their elimination is an interdisciplinary area of interest for many researchers. This paper presents Variable Step Size Least Mean Square (VSS-LMS) approach for harmonics estimation and Shunt Active Power Filter (SAPF) with two-level Hysteresis Current Control (HCC) technique for their elimination in a three-phase distribution system. In the estimation process, the weight is updated using VSS-LMS algorithm. Harmonics components are estimated from the updated weights. In order to mitigate harmonics produced by the nonlinear load connected in a three-phase distribution system, SAPF with two-level HCC is proposed. A three-phase insulated gate bipolar transistor (IGBT) based current controlled voltage source inverter (CC VSI) with a dc bus capacitor is used as an active power filter. The first step is to calculate SAPF reference currents from the sensed nonlinear load currents by applying the synchronous detection method and then the reference currents are fed to the proposed controller for generation of switching signals. The nonlinear load consists of one three-phase and one single-phase diode rectifier feeding R–L load, so that the effectiveness of the two-level HCC scheme to compensate for unbalanced nonlinear load can be tested. Various simulation results are presented to verify the good behavior of the SAPF with proposed two levels HCC.

Single-phase high power factor hybrid rectifier suitable for high-power applications

The study presents the development and the experimental analysis of a new single-phase hybrid rectifier with high power factor (HPF) and low harmonic distortion of current (THDI), suitable for high-power application. The proposed structure is composed by an ordinary single-phase diode rectifier with parallel connection of a switched converter. It is demonstrated that the switched converter is capable of composing the input line current waveform assuring HPF and low THDI, however, the power rating of the switched converter is lesser than 50% of the total output power, assuring robustness and reliability for the proposed hybrid rectifier. A prototype rated at 10 kW was developed and analysed in the laboratory, using low-cost analogue control technique. A pulse-width modulation (PWM) control strategy was implemented imposing quasi-sinusoidal input line current waveform and limiting the switched converter power contribution. It was found that the input line current harmonic spectrum is in accordance with the harmonic limits imposed by IEC61000-3-4. The principle of operation, the mathematical analysis and experimental results from a 10 kW prototype are also presented in this paper.

Average Current Control of a Series-Type Single-Phase PFC With Hybrid Modulation

This letter proposes a hybrid modulation scheme for the average current control (ACC) of the series-type single-phase power factor correction (PFC). The series PFC is a newly developed harmonic correction method for single-phase diode rectifier. It is composed of a hybrid full-bridge inverter and is in cascade between the dc terminal of the diode rectifier and the dc load. When the conventional ACC is applied, due to the large duty-ratio variation at the low-frequency transition points, the line current waveforms exhibit large distortion at the low-frequency switching points. A hybrid scheme, which combines the leading-edge and the trailing-edge modulation, is developed to overcome this problem. The reference signal selection and control logic design are discussed and implemented. Experimental results show that the proposed hybrid approach is able to reduce the harmonic distortion in the line current significantly, as compared with the conventional ACC control.