Kind Of Converter Research Articles

Выявление перспективных способов преобразования параметров электрической энергии

This paper performs an analysis of the electric power conversion methods, and also examines the development trends of DC-to-DC, AC-to-AC, AC-to-DC and DC-to-AC power converters with the use of the International Patent Classification (2023). A comparison has been made of such different kinds of converters as power converters with intermediate conversion and without intermediate conversion into AC or DC, converters using devices of a transistor and thyristor type, and specific circuit implements corresponding to the IPC classification. Perspective directions of such converters’ development have been revealed. The analysis was carried out on the basis of the US patents databases which were formed by the authors for the IPC groups H02M3, H02M5, H02M7 within 2012 to 2023. The perspective directions were revealed by constructing time series of the US patents for the analyzed power converters and their further comparison by the issued patents number and growth patterns. As a result of research, the advantage of transistor converters circuits has been proved, the perspective development directions of the electric power parameters conversion methods as well as their implementation have been described. There was found a decrease of the issued US invention patents in the considered IPC groups by 40% within 2019 to 2022.

Inverse decoupling internal model control for multilevel buck converter with constant power load

Multilevel buck converter has attracted much attention in power electronic systems for their advantages of low switching voltage stress, small filter size and easy capacity expansion. However, this kind of converter has the characteristics of multivariable, strong coupling and nonlinearity, which challenges the voltage balance of flying capacitor and the stability of output voltage. Meanwhile, a large number of electronic loads are connected to the multilevel buck converter. These loads are usually regarded as constant power loads (CPLs) with negative impedance characteristics, which seriously degrades the stability of the power system. This paper proposes an inverse decoupling internal model control strategy for a multilevel buck converter with CPL. A nonlinear mathematical model of the multilevel buck converter with CPL is built, and the reversibility of the model is analyzed based on the inverse system theory. The inverse system expression is derived, and the model is linearized and decoupled into multiple pseudo-linear subsystems, which offsets the effect of the negative impedance characteristics. By selecting filters, internal model controllers are designed for the pseudo-linear subsystems. Furthermore, the stability and robustness of the control system are explored. Compared with other control methods, experimental results show that the proposed control strategy has better dynamic regulation performance and stronger robustness against disturbances.

A Novel Multilevel DC–DC Flyback Converter-Fed H-Bridge Inverter

The objective is to produce a high-gain DC to DC flyback boost converter integrated with a multi-level converter for inverter applications. It has two stages: the first one is flyback multilevel converter, and another level comprises level controller and H-Bridge Inverter. The addition of voltage multiplier cells enhances the commercial flyback converter with multiple voltage outputs producing high voltage gain. These multiple outputs are fed to an H-bridge inverter for producing a multilevel output in an inverter. This DC-to-DC converter steps up the DC supply, but it also decreases the switches, diodes, and capacitors. This kind of converter not only reduces the switch count but also reduces the voltage stress, and total harmonic distortion. To increase the number of levels in the converter, the number of capacitors and diodes in the DC-to-DC converter without disturbing the main circuit must be increased to achieve the required output voltage. The number of power switches for the proposed topology is compared to comparable topologies in the current literature. The results of the simulation are communicated via the MATLAB/ Simulink domain, and the recommended converter’s functionality is demonstrated.

AN ENHANCED POWER DC-AC BUCK CONVERTER

ABSTRACT: This paper presents an enhanced power DC-AC buck converter.The main aim of this research paper is to ensure that the conventional H-bridge DC-AC buck converter is operated practically without delay time between the complementary power switches on the same leg.The enhanced version is realized by serially connecting sized inductor-capacitor-diode topology between the drains and the sources of the high sides of the H-bridge converters. The significant improvement in this kind of converter is that it offers short-circuit immune systems that are not obtainable in the traditional buck DC-AC converter and it triggers the complementary power switches without delay time. The power circuit is obtained by an amalgamation of two Y-closed-up topologies to form an H-bridge converter. The proposed system has a power rating of 3.25 kW, THD of 0.2717%, and pure sine waveforms of output voltage and currentof 311.00V and 10.63A under resistive loads. Under RL loads, it offers 3.25 kW, THD of 0.2807%, and pure sine waveforms of output voltage and current of 297.5V and 10.925A Keywords: DC-AC Converter, traditional, Buck, Enhanced, Power

Research on the Period-Doubling Bifurcation of Fractional-Order DCM Buck–Boost Converter Based on Predictor-Corrector Algorithm

DC–DC converters are widely used. They are a typical class of strongly nonlinear time-varying systems that show rich nonlinear phenomena under certain working conditions. Therefore, an in-depth study of their nonlinear phenomena, characteristics, and generation mechanism is of great practical significance for gaining a deep understanding of this kind of switching converter, revealing the essence of these nonlinear phenomena and then optimizing the design of this kind of converter. Based on the fact that most of the inductance and capacitance are fractional-order, the nonlinear dynamic characteristics of the fractional-order (FO) DCM buck–boost converter are researched in this paper. The main research work and achievements of this paper include: (1) using the predictor–corrector method of fractional calculus, which is not limited by fractional order and can directly calculate the accurate values of the inductance current and capacitor voltage of the fractional converter; the predictor–corrector model of the FO converter is established. (2) The bifurcation diagrams are obtained based on this model, and the period-doubling bifurcation and chaotic behavior of the FO buck–boost converter are analyzed. (3) The phase diagrams are obtained and verified to the point that period-doubling bifurcation occurs; then, some conclusions are drawn. The results show that under certain operating and parameters conditions, the FO buck–boost converter will appear as a bifurcation and chaotic nonlinear phenomenon. Under the condition of the same circuit parameters, the stability parameter domains of the integer-order buck–boost converter and the FO buck–boost converter are different. Compared with the integer-order converter, the parameter stability region of the FO buck–boost converter is bigger. The FO buck–boost converter is more accurate at describing the nonlinear dynamic characteristics. Furthermore, the predictor–corrector method can also be applied to other FO power converters and provides theoretical guidance for converter parameter optimization and controller design.

Selective Harmonic Elimination Technique for a 27-Level Asymmetric Multilevel Converter

In this paper, we present an implementation of selective harmonic elimination modulation technique in a 27-Level asymmetric multilevel converter. The main issue in this kind of converters is the generation of the gating patterns to obtain an optimized AC voltage waveform. State-of-the art solutions use deep mathematical analysis in the frequency domain by means of the Fourier series, but they are mainly applied for two-level or symmetric multilevel converters. On the other hand, the modulation for asymmetric multilevel converters is mainly focused on nearest level control or nearest vector control. In this work, we propose a novel modulating technique that takes advantage of the switching angles optimization for a 27-level waveform. In fact, different set of solutions are obtained and presented in order to define the modulation index as well as the value of the switching angles for the multilevel waveform. A modulation index sweep was performed for the entire operating region of the converter, where it can be observed that the number of levels decreases when the modulation index is low, which are calculated in order to minimize the total harmonic distortion (THD) of the resulting voltage waveform. In order to validate the proposal, these results for different modulation indexes values are simulated, obtaining a THD < 5% for a modulation index 0.75<M<1.0. Finally, a small scale proof-of-concept prototype is implemented in order to validate the proposal.

A New Method for Simplifying Complex DC Systems and Obtaining the Controller Droop Coefficients

DC grid has become an important application in power transmission. However, the exist works only have the method to obtain the droop coefficient in a radial topology. Also, this droop coefficient is for V-I droop control. There is no such like method to obtain the droop coefficient for the P-V droop control. This paper proposed a new method for a complex dc grid to obtain the droop coefficients. Firstly, based on the converter control strategies, the types of converter were classified. It will help to find out which kinds of converter can be participated into the dc-side voltage control. Secondly, a virtual node was defined, and the matrix of the dc grid was reshaped to fit the new added virtual node by using the proposed simplification method. An example was shown how this method worked. After that a new method of calculating the P-V droop coefficient was proposed. Finally, a simulation model was investigated to verify if the proposed method can operate in a real system. The results showed that the simplification method can ensure the mathematical relationships of the dc system. And simulations show good performances of the droop coefficient calculation method.

Low Switching Frequency Operation Control of Line Voltage Cascade Triple Converter

With the increasing power level of wind power generation system, the traditional topology of power converters can no longer meets the demand of high-power wind power generation systems due to the limitation of device performance. The line voltage cascade type multiple PWM converter (LVC-VSC) is a kind of converter that uses the traditional two-level and six-switch voltage source converter as the basic component unit, and each unit is combined with the line voltage cascade method. This type of converter is suitable for medium-voltage and high-power applications such as wind power generation and metallurgical drives because of its easy modularization, strong scalability and low number of isolated power supplies required. However, for medium-voltage and high-power applications, the switching frequency of power devices in the converter is low, usually limited to a few hundred hertz. The traditional modulation method of line voltage cascade converter has a large number of redundant states, and simply reducing the carrier ratio will cause serious degradation of control performance and system instability. To address this problem, this paper proposes a modulation strategy and a corresponding control method for low switching frequency. The modulation strategy is based on the vector relationship of finite switching states, and the optimal switching sequence is selected according to the modulation system by removing redundant states, thus ensuring the application of different modulation sequences under different modulation depths and ensuring the current quality on the basis of the minimum switching frequency, which effectively solves the control problems at low switching frequency. The experimental results show the correctness and effectiveness of the proposed modulation strategy and control method.

A Complete Control System for a High Voltage Converter in an Electrostatic Precipitator

Nowadays, the emission of pollutant particles is a global problem in terms of limiting pollution in industries, as well as greenhouse gases emissions. There are different ways to filter undesired particles, such as carbon air filters, chemical washing, and so on. One of the most popular techniques is the use of electrostatic precipitators: The operation mode is based in attracting particles using electrostatic forces. In order to do that, it is necessary to use a high-voltage converter, with a relative complex control. This article deals with the design of a complete platform to control not only these kind of converters, but also those converters based on the full-bridge power topology.

Digital-to-time converter for test equipment implemented using FPGA DSP blocks

This paper presents a novel digital-to-time converter (DTC) implemented using digital signal processing (DSP) blocks built in field-programmable gate array (FPGA) devices. The converter was implemented in a low-cost Xilinx Spartan-6 FPGA chip manufactured in the 45 nm CMOS process and can be applied in any other programmable logic device that contains DSP blocks. The designed DTC time interval jitter is below 2.8 ps. This is the lowest time interval jitter so far reported in such kind of circuits implemented in a programable device. The obtained resolution of up to 8.6 ps is about twice as good as that achieved in a single carry-chain-based delay-line. Furthermore, the designed circuit saves FPGA general-purpose logic (programmable logic blocks). This kind of converter can be especially useful as a part of test instrumentations as well as time-domain signal processing systems implemented in the latest generation of programmable logic devices.

Power electronic transformers: A review

The medium frequency transformer is a key component for the design of input–output isolated converter design when the isolation and/or voltage matching is needed. These kinds of converters are used in different applications such as battery based energy storage systems, the high voltage DC conversion, grid interfaces of renewable energy sources, etc. Design at the high frequency significantly decreases the size and improves the efficiency of the power transformer. With the recent advancements of soft magnetic core materials and switching devices, the high frequency transformers become more interesting not only as a part of power converters but also as a replacement of conventional line frequency transformers. In this detailed review study, studies on the design of the power transformers used in power electronic converters are examined and their application areas, operating frequency values, core material types are investigated and classified. In addition, the design methodology is proposed with Finite Element Analysis (FEA) software and a power electronic transformer is designed with the different core materials.

A Universal Wideband Device-Level Parallel Simulation Method and Conducted EMI Analysis for More Electric Aircraft Microgrid

The validation of electromagnetic compatibility for the microgrid of a more electric aircraft (MEA) is an essential test item before delivery for a trial flight, and it has always been urgently expected to be involved during the design stage. This article presents a universal method for wideband modeling and simulation of the MEA microgrid system in the time domain, regardless of the fact that motors are driven by which kind of converter, e.g., modular multilevel converter (MMC), 3-L neutral-point clamped (NPC), or 2-L pulsewidth modulation (PWM) converters. The insulated gate bipolar transistor and diodes are modeled with the physics-based dynamic model to emulate not only precise system-level performance of the system, but also to get an insight into the high-frequency oscillation between junction capacitance of the semiconductor modules and the parasitic parameters and high-frequency branch of other components, such as the permanent magnet synchronous motor (PMSM), transformer, and generator. To alleviate the attendant computational challenge, which could be extremely time-consuming (if no nonconvergence problem is encountered) when solved on traditional simulation platform, circuit partition based on transmission line decoupling, Norton equivalent parameter extraction, and TLM-link decoupling of submodules from the MMC bridge arms are utilized. The simulation program is executed on GPU to achieve massively parallel and accelerated solution. The accuracy and efficiency of the GPU-based parallel algorithm are validated by the comparison with the experimentally verified model in ANSYS Simplorer.

The design of isolated multiphase interleaved converter for battery charging of military applications

In this paper, an isolated four-phase interleaved boost converter (I4PIBC) is presented for battery charging of military applications that overcomes the problem of high input current and output voltage ripples. Also, these kinds of converters are used in order to decrease the input current through each element. However, the current will be equal in all inductors. Moreover, the switching frequency is high to minimize the components. This converter is controlled by the proportional–integral–controller with high frequency. The input and output are isolated using high-frequency switch mode power supply transformer. And there will be also experimental comparison on our next study. The simulation results will be presented for closed-loop I4PIBC using MATLAB/Simulink Program.

A Simple Space Vector Modulation of High-Frequency AC Linked Three-Phase-to-Single-Phase/DC Converter

High frequency (HF) ac linked converter functions well to interface between buses with different voltage types. Using a three-phase-to-single-phase matrix converter, a single-phase cyclo converter, and a HF transformer, we can compose a HF ac linked converter to interface between three-phase ac grids and single-phase ac or dc distributed generations (DGs). In this paper, a novel space vector modulation (SVM) method is proposed for such kind of converter. The proposed SVM method converts the mains three-phase ac voltage to a HF ac voltage at the primary side of transformer, and then unfolds the HF ac voltage to a single-phase ac or dc voltage at the secondary side of transformer. Without need to compute separate switching signals for the primary and secondary converters and then coordinate their operations elaborately, the proposed SVM method can be easily implemented by incorporating the HF chopping into the SVM of traditional indirect matrix converter. Therefore, no complicated duty cycle computation or elaborate switching states combination is required. Simulation and hardware-in-loop implementation demonstrate the validity of the proposed method.

Chaos versus EMI: Methodologies and Practice

This paper gives a review on the methodologies of using the continuous power spectrum feature of chaos to suppress electromagnetic interference (EMI), which have been extensively studied in the past 15 years, and their practical applications in power electronic converters of various topologies and powers, which have been widely employed in various electrical and electronic devices in our daily lives and thus form the main sources of EMI. This paper not only points out that chaotic modulation is effective and feasible in improving the electromagnetic compatibility (EMC) of various types of power electronic converters, but also gives the circuit design methodologies for different kinds of converters, especially the design methods of modules and chips. It can serve as a guide for engineering applications.

Real-Time Validation of a Sliding Mode Controller for Closed-Loop Operation of Reduced Switch Count Multilevel Inverters

The prominence of reduced switch count multilevel inverters is rising owing their merits of decreased number of switches and modular structures. There are topologies that use more than one source; however, utilization of all the sources at all levels is seldom. These topologies will diminish the energy efficiency of the conversion system as all the sources will not deliver the power except at the highest level in the output voltage. These kinds of converters can hamper the penetration of renewable energy into the existing energy mix, as the energy capacity of the renewable source is undermined. In this connection, this paper explores a three-phase multilevel inverter that can extract the power from all the sources at all the levels through series/parallel switchings. Besides, this paper develops a sliding mode based nonlinear controller for closed-loop operation of the multilevel inverter, which is not addressed sufficiently in the literature. The performance of the developed variable gain nonlinear controller is validated against the PI controller for delivering desired powers under different operating conditions/disturbances using simulations and in real-time environment.

Analysis, design and performance evaluation of an LED driver with unity power factor and constant-current primary sensing regulation

This work focuses on an isolated offline driver to power LED lamps, realized with a high-power-factor quasi-resonant (Hi-PF QR) flyback converter with peak current mode control and employing constant-current primary-sensing regulation (CC-PSR). The converter is controlled with a recently introduced control technique that enables this kind of converter to ideally draw a sinusoidal current from the input source and, at the same time, to accurately regulate the dc output current using only quantities available on the primary side. The resulting absence of an optocoupler or other means crossing the isolation barrier to close a feedback loop not only reduces size and cost of the driver but also brings greater safety and reliability. The analysis addresses those factors inherent in the control method that affect the shape of the input current that have not been covered in the existing literature. The aim is to set up some design guidelines to minimize the Total Harmonic Distortion (THD) of the input current. The experimental work shows that using this technique enables the design of an LED driver for wide range mains (90 to 264 Vac) that achieves output current regulation better than ±2%, power factor close to unity and THD of the input current <10% over the input voltage range and over a 2:1 range of the output voltage.

Finite-Set Model Predictive Control of an Asymmetric Cascaded H-bridge photovoltaic inverter

This paper presents a Finite-Set Model Predictive Control (FS-MPC) method adapted for an Asymmetric and Cascaded H-bridge Photovoltaic inverter (ACHB). This advanced control approach is designed to: Ensure an independent Maximum Power Point Tracking (MPPT), Synthesize at the inverter output a sinusoidal multistep PWM waveform, and provide an output current with unity power factor and low harmonic distortion. ACHB seems to be a perfect candidate for Photovoltaic systems. However, the control of such kind of converters is quite a challenging task. On the other hand, FS-MPC has achieved great popularity due to the ease with which the constraints, nonlinearities, and switching actions can be included in the controller formulation.Classical approach to tune the FS-MPC parameters is not fruitful for an ACHB. In this concern, we propose, new and dynamic, parameters for the FS-MPC algorithm. This approach is evaluated under different operating conditions including robustness tests.Results provide that the proposed FS-MPC method features a great flexibility and control potential.

Switched Polytopic Controller Applied on a Positive Reconfigurable Power Electronic Converter

The reconfigurable power electronic converters (RPECs) are a new generation of systems, which modify their physical configuration in terms of a desired input or output operation characteristic. This kind of converters is very attractive in terms of versatility, compactness, and robustness. They have been proposed in areas such as illumination, transport electrification (TE), eenewable energy (RE), smart grids and the internet of things (IoT). However, the resulting converters operate in switched variable operation-regions, rather than over single operation points. As a result, there is a complexity increment on the modeling and control stage such that traditional techniques are no longer valid. In order to overcome these challenges, this paper proposes a kind of switched polytopic controller (SPC) suitable to stabilize an RPEC. Modeling, control, numerical and practical results are reported. To this end, a 400 W positive synchronous bi-directional buck/boost converter is used as a testbed. It is also shown, that the proposed converter and robust controller accomplish a compact, modular and reliable design during different working configuration, operation points and load changes.

Black-Box Calibration for ADCs With Hard Nonlinear Errors Using a Novel INL-Based Additive Code: A Pipeline ADC Case Study

This paper presents a digital nonlinearity calibration technique for ADCs with strong input–output discontinuities between adjacent codes, such as pipeline, algorithmic, and SAR ADCs with redundancy. In this kind of converter, the ADC transfer function often involves multivalued regions, where conventional integral-nonlinearity (INL)-based calibration methods tend to miscalibrate, negatively affecting the ADC’s performance. As a solution to this problem, this paper proposes a novel INL-based calibration which incorporates information from the ADC’s internal signals to provide a robust estimation of static nonlinear errors for multivalued ADCs. The method is fully generalizable and can be applied to any existing design as long as there is access to internal digital signals. In pipeline or subranging ADCs, this implies access to partial subcodes before digital correction; for algorithmic or SAR ADCs, conversion bit/bits per cycle are used. As a proof-of-concept demonstrator, the experimental results for a 1.2 V 23 mW 130 nm-CMOS pipeline ADC with a SINAD of 58.4 dBc (in nominal conditions without calibration) is considered. In a stressed situation with 0.95 V of supply, the ADC has SINAD values of 47.8 dBc and 56.1 dBc, respectively, before and after calibration (total power consumption, including the calibration logic, being 15.4 mW).