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20 pages, 3866 KiB

Open AccessArticle

Parallel Control of Converters with Energy Storage Equipment in a Microgrid

by Guopeng Zhao and Hongwei Yang

Electronics 2019, 8(10), 1110; https://doi.org/10.3390/electronics8101110 - 2 Oct 2019

Cited by 5 | Viewed by 2562

Abstract

The converter in a microgrid uses the active power and reactive power (PQ) control strategy when connected to the grid. In the case of failure of large power grid, the converters are required to be connected in parallel under the condition of island [...] Read more.

The converter in a microgrid uses the active power and reactive power (PQ) control strategy when connected to the grid. In the case of failure of large power grid, the converters are required to be connected in parallel under the condition of island to provide power to the load. In this paper, a new control method for the parallel operation of converters based on V/F control is proposed. The V/F control is used to ensure the output voltages have the same amplitude and frequency, then the converters will only produce circulating current caused by phase angle inconsistency. The phase angle self-synchronization strategy is proposed to make sure the phase angle of output voltage of all converters in the system are consistent. First, a large inductor is added to the end of the converter to ignore the line reactance, through this, the measured voltage at the terminal of the converter roughly equals to the voltage of the load, thus, every converter has the same reference of phase angle. Using the proposed phase angle self-synchronization strategy allows the output voltage of every converter to have the same phase angle, so that there is no circulating current between converters, and the power is evenly distributed among the converters. The simulation verification was carried out on the Power Simulation (PSIM) simulation platform, and the experimental verification was implemented on the hardware experimental platform. Both results demonstrate the effectiveness of the proposed strategy. This method is highly reliable and easy to implement, and the circulating current can be reduced effectively. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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15 pages, 6599 KiB

Open AccessFeature PaperArticle

DC-AC Isolated Power Converter Array. Focus on Differential Mode Conducted EMI

by Jean-Christophe CREBIER, Thanh-Hai PHUNG, Van-Sang NGUYEN, Theo LAMORELLE, Andre ANDRETA, Lyubomir KẺACHEV and Yves LEMBEYE

Electronics 2019, 8(9), 999; https://doi.org/10.3390/electronics8090999 - 6 Sep 2019

Cited by 4 | Viewed by 2865

Abstract

This paper introduces the implementation of a DC–AC step up isolated converter from associations of bidirectional Conversion Standard Cells (CSCs). The designed multi-cell converter is an array of standardized converter cells. It is described and then compared to a reference converter with respect [...] Read more.

This paper introduces the implementation of a DC–AC step up isolated converter from associations of bidirectional Conversion Standard Cells (CSCs). The designed multi-cell converter is an array of standardized converter cells. It is described and then compared to a reference converter with respect to differential mode conducted electro-magnetic interference (EMI). The paper outlines the motivation for developing a generic multi-cell approach before underlining the benefits from the point of view of conducted EMI when implementing power converter arrays (PCAs). In particular, it is shown that in PCAs, the differential mode (DM) EMI filter can advantageously utilize distributed CSCs, making it possible to use very low value AC inductors to filter the AC current ripple. Experimental results are provided to validate the analysis carried out in the paper. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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20 pages, 6774 KiB

Open AccessArticle

Research on the System and Control Strategy of an AC-DC Hybrid Single-Phase Electric Energy Router

by Guopeng Zhao, Chao Jiang and Jiaxing Liu

Electronics 2019, 8(9), 970; https://doi.org/10.3390/electronics8090970 - 30 Aug 2019

Cited by 5 | Viewed by 3520

Abstract

With the extensive development and use of new energy sources, it has become an urgent issue to solve the problem how to effectively use such energy sources. This paper designs a single-phase electric energy router (SPEER) whose main goal is to solve the [...] Read more.

With the extensive development and use of new energy sources, it has become an urgent issue to solve the problem how to effectively use such energy sources. This paper designs a single-phase electric energy router (SPEER) whose main goal is to solve the problem of optimal operation of the home power system under a high penetration rate of new energy. First, a SPEER structure is presented which has an AC-DC hybrid form to meet the power requirements of all household electrical equipment. Compared with the existing structures, its structural design is more suitable for small-capacity systems, such as home power systems. Next, a reasonable, detailed, and feasible control scheme was designed for each part of the SPEER, so that it has the functions of plug and play, power routing, island detection, and synchronous grid connection, and a seamless coordination management scheme between subsystems was designed. Complete functions make it more intelligent in response to various conditions. Finally, the correctness of the designed SPEER and control strategy was verified by experiment. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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20 pages, 6018 KiB

Open AccessFeature PaperArticle

Impact of Component Dispersion in DC to DC Low-Power Low-Voltage Power Converter Array

by Jean-Christophe Crebier, Theo Lamorelle, Silvain Marache, Thanh Hai Phung, Van-Sang Nguyen, Andre Andreta, Jean Christophe Podvin and Yves Lembeye

Electronics 2019, 8(9), 917; https://doi.org/10.3390/electronics8090917 - 21 Aug 2019

Cited by 1 | Viewed by 3094

Abstract

The paper deals with arrays of numerous power conversion cells, associated in series and/or in parallel to build larger step up or step down direct current (DC)/DC isolated converters. The work focuses on the impact of the spread and distribution of the conversion [...] Read more.

The paper deals with arrays of numerous power conversion cells, associated in series and/or in parallel to build larger step up or step down direct current (DC)/DC isolated converters. The work focuses on the impact of the spread and distribution of the conversion cell characteristics on the characteristics and performance of the power converter array (PCA). Based on a characterization protocol, about 130 conversion standard cells (CSC) are characterized and classified from a statistical point of view. Three families are defined and representatives are chosen and implemented in various configurations, in open and closed loop control, to analyze the impact of their spread characteristic over the global converter, the PCA. The paper is based on an extended practical set up and protocols, all described in details. Guidelines on CSCs implementation with respect to their dispersion are provided at the end on the paper. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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18 pages, 8378 KiB

Open AccessArticle

Active Power Decoupling Design of a Single-Phase AC–DC Converter

by Mingjie Qiu, Ping Wang, Huakun Bi and Zhishuang Wang

Electronics 2019, 8(8), 841; https://doi.org/10.3390/electronics8080841 - 27 Jul 2019

Cited by 11 | Viewed by 6225

Abstract

The second-order ripple power of single-phase converter causes second-order ripple voltages on the DC bus. For eliminating second-order ripple components, passive power decoupling methods including DC bus electrolytic capacitors have some shortcomings, such as low power density and poor stability of converters. Thus, [...] Read more.

The second-order ripple power of single-phase converter causes second-order ripple voltages on the DC bus. For eliminating second-order ripple components, passive power decoupling methods including DC bus electrolytic capacitors have some shortcomings, such as low power density and poor stability of converters. Thus, an active power decoupling method based on a single-phase converter is proposed in this paper. The control method, taking single-phase voltage source pulse width modulation (PWM) rectifier (single-phase VSR) as the basic converter and adopting a buck-boost power decoupling circuit, introduces second-order ripple of DC bus voltage into a power decoupling circuit. The ripple acts as compensation of the phase deviation between the command value and the actual value of the second-order ripple current. Therefore, estimation of the second-order ripple current is more accurate, the power decoupling circuit absorbs the second-order ripple power behind the H-bridge more completely, and the DC bus voltage ripple is effectively suppressed accordingly. Finally, experimental results of the single-phase VSR are given to verify the validity of the proposed method. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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22 pages, 10928 KiB

Open AccessArticle

A Novel Dual Integrated LLC Resonant Converter Using Various Switching Patterns for a Wide Output Voltage Range Battery Charger

by Bong-Yeon Choi, Soon-Ryung Lee, Jin-Wook Kang, Won-Sang Jeong and Chung-Yuen Won

Electronics 2019, 8(7), 759; https://doi.org/10.3390/electronics8070759 - 6 Jul 2019

Cited by 4 | Viewed by 4677

Abstract

This paper proposes a novel dual integrated LLC resonant converter (DI-LRC) with a wide output voltage range using various switching patterns. The primary side of the proposed DI-LLC converter consists of two resonant tanks and six switches, while the secondary side consists of [...] Read more.

This paper proposes a novel dual integrated LLC resonant converter (DI-LRC) with a wide output voltage range using various switching patterns. The primary side of the proposed DI-LLC converter consists of two resonant tanks and six switches, while the secondary side consists of a six-pulse diode rectifier. Depending on the switching pattern of the primary switch, the DI-LRC converter is performed by single full-bridge operation with a voltage gain of 1, series-connected full-bridge operation with a voltage gain of 0.5, series-connected half bridge operation with a voltage gain of 0.25, and parallel-connected full-bridge operation with a voltage gain of 2. Accordingly, the proposed DI-LRC converter has four voltage gain curves with different variations and achieves a wider output voltage range than the conventional single voltage gain curve in a given operating frequency range. In this paper, the equivalent circuits derived for each switching pattern are proposed to analyze the operating characteristics of the proposed converter according to each switching pattern, and each Q factor and voltage gain are calculated based on the analyzed equivalent circuit. The performance of the proposed converter and switching pattern is verified using the simulation and experimental results of the prototype battery charger, which is designed to be 4-kW class. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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18 pages, 9567 KiB

Open AccessArticle

Analysis and Design of a ZVT Resonant Boost Converter Using an Auxiliary Resonant Circuit

by Hee-Jun Lee and Young-Ho Kim

Electronics 2019, 8(4), 466; https://doi.org/10.3390/electronics8040466 - 25 Apr 2019

Cited by 6 | Viewed by 5186

Abstract

In this paper, a new zero voltage transition (ZVT) resonant boost converter is proposed. A typical boost converter generates switching losses at turning on and turning off, and these losses cause a reduction in the efficiency of the whole system. This proposed ZVT [...] Read more.

In this paper, a new zero voltage transition (ZVT) resonant boost converter is proposed. A typical boost converter generates switching losses at turning on and turning off, and these losses cause a reduction in the efficiency of the whole system. This proposed ZVT resonant boost converter utilizes a soft switching method, using an auxiliary circuit with a resonant inductor, capacitor, and two auxiliary switches. Therefore, it can reduce switching losses more so than the conventional hard switching converter. Also, the conduction period of the resonant inductor current is reduced by using a modified circuit. An experiment is conducted with the converter, which steps up the voltage from 200 V to 380 V and its switching frequency and output power are 30 kHz and 4 kW, respectively. It is confirmed that the experimental results and simulation results are the same and the validity of this proposed converter is verified. The conventional converter and proposed converter are analyzed by comparing the experimental results of two converters under the same conditions. It is confirmed that all switches can achieve soft switching and the proposed converter improves on the conventional converter by measuring the efficiency of two converters. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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13 pages, 6758 KiB

Open AccessArticle

Impedance-Source DC-to-AC/DC Converter

by Rajendran Sivapriyan and Devaraj Elangovan

Electronics 2019, 8(4), 438; https://doi.org/10.3390/electronics8040438 - 16 Apr 2019

Cited by 4 | Viewed by 4548

Abstract

This article presents a novel impedance-source-based direct current (DC)-to-alternating current (AC)/DC converter (Z-Source DAD Converter). The Z-Source DAD converter converts the input DC voltage into AC or DC with buck or boost in the load voltage. This Z-Source DAD conversion circuit is a [...] Read more.

This article presents a novel impedance-source-based direct current (DC)-to-alternating current (AC)/DC converter (Z-Source DAD Converter). The Z-Source DAD converter converts the input DC voltage into AC or DC with buck or boost in the load voltage. This Z-Source DAD conversion circuit is a single-stage power conversion system. This converter circuit converts the input DC voltage into variable-magnitude output DC voltage or converts the DC voltage into a variable-magnitude output AC voltage. The higher voltage magnitude in boost mode can be controlled by controlling the shoot-through (ST) state timing of the converter. MATLAB-Simulink simulation and microcontroller-based hardware circuit results are presented to demonstrate power conversion with the buck and boost features of the Z-Source DAD converter for both types of output voltages. The simulation and experimental results show that the Z-Source DAD converter converts the given DC supply into AC or DC with buck or boost in the output load voltage. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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28 pages, 8642 KiB

Open AccessArticle

Scalable Single-Phase Multi-Functional Inverter for Integration of Rooftop Solar-PV to Low-Voltage Ideal and Weak Utility Grid

by Venkata Subrahmanya Raghavendra Varaprasad Oruganti, Venkata Sesha Samba Siva Sarma Dhanikonda and Marcelo Godoy Simões

Electronics 2019, 8(3), 302; https://doi.org/10.3390/electronics8030302 - 7 Mar 2019

Cited by 6 | Viewed by 4399

Abstract

Integration of rooftop solar-PV (RTSPV) systems and extensive use of nonlinear loads in the low-voltage distribution system (LVDS) leads to poor power quality (PQ). Therefore, it is necessary to address the issues leading to poor PQ at the point of common coupling of [...] Read more.

Integration of rooftop solar-PV (RTSPV) systems and extensive use of nonlinear loads in the low-voltage distribution system (LVDS) leads to poor power quality (PQ). Therefore, it is necessary to address the issues leading to poor PQ at the point of common coupling of the LVDS. In this article, a multi-band hysteresis current control (MB-HCC) for the multi-functional inverter (MFI) is proposed which improves the efficiency of the MFI and also enhances the PQ of the LVDS. The MB-HCC uses simple switching logic and outperforms in its multi-functional tasks such as active power injection and power conditioning. MB-HCC offers better efficiency over variable double-band HCC (VDB-HCC) as it operates at a lower switching frequency. The performance of the proposed system is simulated by using MATLAB/Simulink and validated by OPAL-RT based real-time simulation studies. During the variation of solar irradiation, the proposed MFI has an average efficiency of 98.5% under the ideal grid and 97.34% under the distorted grid. Moreover, the percentage of Total Harmonic Distortion under ideal and distorted grid conditions is brought down to below 5%, and also, reactive power compensation maintains unity power factor operation complying with the IEEE-519-2014 and 1547 standards. These results substantiate the hypothesis of scalability of the single-phase MB-HCC-based MFI for an LVDS contributing to economy and ecology. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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Graphical abstract

9 pages, 1503 KiB

Open AccessArticle

Sufficient Condition-Based Stability Analysis of a Power Converter Applied Switching Transient Waveform Modification Using Kharitonov’s Theorem

by Tongkai Cui, Qishuang Ma and Ping Xu

Electronics 2019, 8(2), 245; https://doi.org/10.3390/electronics8020245 - 21 Feb 2019

Viewed by 2879

Abstract

The rapid switching action of power metal-oxide-semiconductor field-effect transistor (MOSFET) causes high-level electromagnetic interference (EMI) in power converters. The switching transient waveform modification method realized by closed-loop gate drive has been recognized as an effective high-frequency EMI reduction approach. However, feedback control of [...] Read more.

The rapid switching action of power metal-oxide-semiconductor field-effect transistor (MOSFET) causes high-level electromagnetic interference (EMI) in power converters. The switching transient waveform modification method realized by closed-loop gate drive has been recognized as an effective high-frequency EMI reduction approach. However, feedback control of power MOSFET in the saturation region would introduce stability problems. This paper presents a sufficient condition-based stability analysis of all the operating points during turn-off using Kharitonov’s theorem. Firstly, a small-signal MOSFET model during turn-off was used to derive the closed-loop system transfer function. The nonlinear capacitances and the rest constant parameters of the small-signal model were determined based on the device characteristics and the expected outcome of the drain-source voltage. Then we split the turn-off switching transient into several subintervals, during which the system characteristic equation became an interval polynomial due to the nonlinear capacitances. Finally, Kharitonov’s theorem was applied in each subinterval to evaluate the stability, thereby achieving the overall system stability analysis during turn-off. Experiments were conducted to investigate the system’s stability and the results confirmed the validity of the proposed analysis. This work presents an implementable design guideline for the applied switching transient waveform modification of power converters via closed-loop gate drive. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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18 pages, 7750 KiB

Open AccessArticle

A Nonisolated Three-Port DC–DC Converter with Continuous Input and Output Currents Based on Cuk Topology for PV/Fuel Cell Applications

by Balaji Chandrasekar, Chellammal Nallaperumal and Subranshu Sekhar Dash

Electronics 2019, 8(2), 214; https://doi.org/10.3390/electronics8020214 - 15 Feb 2019

Cited by 21 | Viewed by 5796

Abstract

A nonisolated three-port DC–DC converter based on Cuk topology (NI-TPC) to handle the renewable sources (RS) is proposed in this paper. This converter includes two unidirectional input ports accommodating both a fuel cell (FC) and photovoltaic (PV) cell; and one output port with [...] Read more.

A nonisolated three-port DC–DC converter based on Cuk topology (NI-TPC) to handle the renewable sources (RS) is proposed in this paper. This converter includes two unidirectional input ports accommodating both a fuel cell (FC) and photovoltaic (PV) cell; and one output port with DC load. Due to the inductors at all the ports, it claims the advantage of continuous input and output currents. Additionally, it uses less number of switches, diodes and inductors compared with conventional ‘n-1’ separate Cuk converters. Synthesis procedure for a generalized n-port DC–DC structure is explained. The derivation law based on conventional Cuk converter, operating principle, design calculation, and analysis are presented in detail, and then the analysis is validated through simulation and a 100W prototype, verifying the performance of the proposed NI-TPC converter. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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17 pages, 3012 KiB

Open AccessFeature PaperArticle

Small-Signal Stability Analysis of Multi-Terminal DC Grids

by Amr Ahmed A. Radwan

Electronics 2019, 8(2), 130; https://doi.org/10.3390/electronics8020130 - 26 Jan 2019

Cited by 4 | Viewed by 3918

Abstract

This paper presents a detailed small-signal analysis and an improved dc power sharing scheme for a six terminal dc grid. The multi-terminal DC (MTDC) system is composed of (1) two voltage-source converters (VSCs) entities operating as rectification stations; (2) two VSCs operating as [...] Read more.

This paper presents a detailed small-signal analysis and an improved dc power sharing scheme for a six terminal dc grid. The multi-terminal DC (MTDC) system is composed of (1) two voltage-source converters (VSCs) entities operating as rectification stations; (2) two VSCs operating as inverting stations; (3) two dc/dc conversion stations; and (4) an interconnected dc networking infrastructure. The small-signal state-space sub-models of the individual entities are developed and integrated to formulate the state-space model of the entire system. Using the modal analysis, it is shown that the most critical modes are associated with the power sharing droop coefficients of the rectification stations, which are constrained by the steady-state operational requirements. Therefore, a second degree-of-freedom compensation scheme is proposed to improve the dynamic response of the MTDC system without influencing the steady-state operation. Time domain simulation results are presented to validate the analysis and show the effectiveness of the proposed techniques. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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21 pages, 4742 KiB

Open AccessArticle

A 10 kW ZVS Integrated Boost Dual Three-Phase Bridge DC–DC Resonant Converter for a Linear Generator-Based Wave-Energy System: Design and Simulation

by Nagendrappa Harischandrappa and Ashoka K. S. Bhat

Electronics 2019, 8(1), 115; https://doi.org/10.3390/electronics8010115 - 21 Jan 2019

Cited by 4 | Viewed by 5605

Abstract

The design and performance analysis of a 10 kW three-phase DC–DC LCL-type resonant converter having a built-in boost function were carried out. This high-power converter is proposed for its application in grid-interfacing a linear generator (LG)-based wave-energy system. Fixed-frequency control is used, and [...] Read more.

The design and performance analysis of a 10 kW three-phase DC–DC LCL-type resonant converter having a built-in boost function were carried out. This high-power converter is proposed for its application in grid-interfacing a linear generator (LG)-based wave-energy system. Fixed-frequency control is used, and the converter was designed to operate with a lagging power factor. It is shown that all switches turn on with zero-voltage switching (ZVS) for wide input voltage and load variations. This results in reduced switching losses and stresses, which is very important in large-power applications. The performance of the converter was studied through PSIM simulation software. Theoretical and simulation results are presented for comparison. Power-loss break-down analysis of the designed converter was carried out and the summary of results is presented. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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14 pages, 6848 KiB

Open AccessArticle

A Hybrid Current Mode Controller with Fast Response Characteristics for Super Capacitor Applications

by Seung-Min Oh, Jae-hak Ko, Hag-Wone Kim and Kwan-Yuhl Cho

Electronics 2019, 8(1), 112; https://doi.org/10.3390/electronics8010112 - 19 Jan 2019

Cited by 4 | Viewed by 5957

Abstract

A wide-bandwidth current-controller is required for the fast charging and discharging of applications containing super capacitors. To accomplish this, peak current mode is generally used due to the speed of its response characteristics. On the other hand, peak current mode control must be [...] Read more.

A wide-bandwidth current-controller is required for the fast charging and discharging of applications containing super capacitors. To accomplish this, peak current mode is generally used due to the speed of its response characteristics. On the other hand, peak current mode control must be provided with a slope compensation function to restrain sub-harmonic oscillations. However, if the controlled output voltage is varied, the slope must be changed accordingly. Nonetheless, it is not easy to change the slope for every change in output voltage. Another solution involves the slope being set at the maximum value, which results in a slow response. Therefore, in this paper, a hybrid mode controller was proposed that uses a peak current and a newly-specified valley current. Using the proposed hybrid mode control, sub-harmonic oscillation did not occur for duty cycles larger than 0.5 and response times were fast. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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14 pages, 1567 KiB

Open AccessFeature PaperArticle

Step-Down Partial Power DC-DC Converters for Two-Stage Photovoltaic String Inverters

by Jaime Wladimir Zapata, Samir Kouro, Gonzalo Carrasco and Thierry A. Meynard

Electronics 2019, 8(1), 87; https://doi.org/10.3390/electronics8010087 - 12 Jan 2019

Cited by 21 | Viewed by 6435

Abstract

Photovoltaic (PV) systems composed by two energy conversion stages are attractive from an operation point of view. This is because the maximum power point tracking (MPPT) range is extended, due to the voltage decoupling between the PV system and the dc-link. Nevertheless, the [...] Read more.

Photovoltaic (PV) systems composed by two energy conversion stages are attractive from an operation point of view. This is because the maximum power point tracking (MPPT) range is extended, due to the voltage decoupling between the PV system and the dc-link. Nevertheless, the additional dc-dc conversion stage increases the volume, cost and power converter losses. Therefore, central inverters based on a single-stage converter, have been a mainstream solution to interface large-scale PV arrays composed of several strings connected in parallel made by the series connections of PV modules. The concept of partial power converters (PPC), previously reported as a voltage step-up stage, has not addressed in depth for all types of PV applications. In this work, a PPC performing voltage step-down operation is proposed and analyzed. This concept is interesting from the industry point of view, since with the new isolation standards of PV modules are reaching 1500 V, increasing both the size of the string and dc-link voltage for single-stage inverters. Since grid connection remains typically at 690 V, larger strings impose more demanding operation for single-stage central inverters (required to operate at lower modulation indexes and demand higher blocking voltage devices), making the proposed step-down PPC an attractive solution. Theoretical analysis and an experimental test-bench was built in order to validate the PPC concept, the control performance and the improvement of the conversion efficiency. The experimental results corroborate the benefits of using a PPC, in terms of increasing the system efficiency by reducing the processed power of the converter, while not affecting the system performance. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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16 pages, 2374 KiB

Open AccessArticle

Model-Based Latency Compensation for Network Controlled Modular Multilevel Converters

by Tomás P. Corrêa, Francisco J. Rodríguez and Emilio J. Bueno

Electronics 2019, 8(1), 22; https://doi.org/10.3390/electronics8010022 - 24 Dec 2018

Cited by 3 | Viewed by 3048

Abstract

The use of an internal digital communication network enhances the scalability, implementation and maintenance of Modular Multilevel Converters (MMC). However, it also introduces delays that limit the sampling frequency and the controller dynamic performance. In this paper, we propose a model-based predictor to [...] Read more.

The use of an internal digital communication network enhances the scalability, implementation and maintenance of Modular Multilevel Converters (MMC). However, it also introduces delays that limit the sampling frequency and the controller dynamic performance. In this paper, we propose a model-based predictor to compensate for the loop delay and overcome these limitations. Two benefits of this approach are possible: either designers can increase the sampling rate and control performance or employ a slower communication protocol/technology. In this paper, we present the mathematical description of the model-based predictor, assess the parameter sensitivity, and show matching simulation and experimental results that validate it. As constraints introduced by the use of digital communications are overcome, the results achieved encourage engineers to adopt a network into the design of Modular Multilevel Converters. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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17 pages, 2937 KiB

Open AccessArticle

AC Mains Synchronization Loop for Precalculated- Based PFC Converters Using the Output Voltage Measure

by Alberto Sanchez, Marina Yushkova, Angel De Castro, M. Sofía Martínez-García and Javier Garrido

Electronics 2019, 8(1), 4; https://doi.org/10.3390/electronics8010004 - 21 Dec 2018

Cited by 1 | Viewed by 3246

Abstract

Common implementations of power factor correction include sensors for the input and output voltages and the input current. Many alternatives have been considered to reduce the number of sensors, especially the current sensor. One strategy is to precalculate the duty cycles that must [...] Read more.

Common implementations of power factor correction include sensors for the input and output voltages and the input current. Many alternatives have been considered to reduce the number of sensors, especially the current sensor. One strategy is to precalculate the duty cycles that must be applied to every ac main, so the system only needs to synchronize them with the input voltage, and include a simple output voltage loop. The main problem with this approach is the sensibility to any synchronization error, because the input current is not measured, so its evolution is not continuously corrected. This paper shows how the synchronization error alters the current and the power factor, and it proposes several methods to detect and correct this error. All methods use the output voltage ADC, which is already used to control the output voltage, so the cost of the system is not increased. This technique can also be applied to any current sensorless PFC converter, because they are usually affected by leading or lagging currents, so the synchronization can be modified to reduce these effects. Results show that the implementation of this synchronization loop keeps a high-power factor under a wide synchronization error range, while the added logic is not significant. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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14 pages, 4790 KiB

Open AccessArticle

Soft Switching DC Converter for Medium Voltage Applications

by Bor-Ren Lin

Electronics 2018, 7(12), 449; https://doi.org/10.3390/electronics7120449 - 18 Dec 2018

Cited by 3 | Viewed by 3391

Abstract

A dc-dc converter with asymmetric pulse-width modulation is presented for medium voltage applications, such as three-phase ac-dc converters, dc microgrid systems, or dc traction systems. To overcome high voltage stress on primary side and high current rating on secondary side, three dc-dc circuits [...] Read more.

A dc-dc converter with asymmetric pulse-width modulation is presented for medium voltage applications, such as three-phase ac-dc converters, dc microgrid systems, or dc traction systems. To overcome high voltage stress on primary side and high current rating on secondary side, three dc-dc circuits with primary-series secondary-parallel structure are employed in the proposed converter. Current doubler rectifiers are used on the secondary side to achieve low ripple current on output side. Asymmetric pulse-width modulation is adopted to realize soft switching operation for power switches for wide load current operation and achieve high circuit efficiency. Current balancing cells with magnetic component are used on the primary side to achieve current balance in each circuit cell. The voltage balance capacitors are also adopted on primary side to realize voltage balance of input split capacitors. Finally, the circuit performance is confirmed and verified from the experiments with a 1.44 kW prototype. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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16 pages, 3123 KiB

Open AccessArticle

Parameter Identification of DC-DC Converters under Steady-State and Transient Conditions Based on White-Box Models

by Jordi-Roger Riba, Manuel Moreno-Eguilaz, Santiago Bogarra and Antoni Garcia

Electronics 2018, 7(12), 393; https://doi.org/10.3390/electronics7120393 - 5 Dec 2018

Cited by 17 | Viewed by 5656

Abstract

This paper proposes a white-box approach for identifying the parameters of DC-DC buck and boost switch mode power converters. It is based on discretizing the differential equations that describe the dynamic behavior of the converters. From the discretized equations and experimental data, the [...] Read more.

This paper proposes a white-box approach for identifying the parameters of DC-DC buck and boost switch mode power converters. It is based on discretizing the differential equations that describe the dynamic behavior of the converters. From the discretized equations and experimental data, the parameters of the converters are identified, thus obtaining both the values of the passive components and the transfer function coefficients of the controller. To this end, steady state and transient experimental signals are analyzed, including the input and output voltages and the inductor and output currents. To determine the accuracy of the proposed method, once the parameters are identified, a simulation with the identified parameters of the converter is run and compared with experimental signals. Such results show the accuracy and feasibility of the approach proposed in this work, which can be extended to other converters and electrical and electronic devices. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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16 pages, 3553 KiB

Open AccessArticle

A Comparative Study of Different Optimization Methods for Resonance Half-Bridge Converter

by Navid Salehi, Herminio Martinez-Garcia and Guillermo Velasco-Quesada

Electronics 2018, 7(12), 368; https://doi.org/10.3390/electronics7120368 - 2 Dec 2018

Cited by 5 | Viewed by 4459

Abstract

The LLC resonance half-bridge converter is one of the most popular DC-DC converters and could easily inspire researchers to design a high-efficiency and high-power-density converter. LLC resonance converters have diverse operation modes based on switching frequency and load that cause designing and optimizing [...] Read more.

The LLC resonance half-bridge converter is one of the most popular DC-DC converters and could easily inspire researchers to design a high-efficiency and high-power-density converter. LLC resonance converters have diverse operation modes based on switching frequency and load that cause designing and optimizing procedure to vary in different modes. In this paper, different operation modes of the LLC half-bridge converter that investigate different optimization procedures are introduced. The results of applying some usual optimization methods implies that for each operation mode some specific methods are more appropriate to achieve high efficiency. To verify the results of each optimization, numerous simulations are done by Pspice and MATLAB and the efficiencies are calculated to compare them. Finally, to verify the result of optimization, the experimental results of a laboratory prototype are provided. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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18 pages, 2092 KiB

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Solid State Transformers Topologies, Controllers, and Applications: State-of-the-Art Literature Review

by Ahmed Abu-Siada, Jad Budiri and Ahmed F. Abdou

Electronics 2018, 7(11), 298; https://doi.org/10.3390/electronics7110298 - 5 Nov 2018

Cited by 53 | Viewed by 11482

Abstract

With the global trend to produce clean electrical energy, the penetration of renewable energy sources in existing electricity infrastructure is expected to increase significantly within the next few years. The solid state transformer (SST) is expected to play an essential role in future [...] Read more.

With the global trend to produce clean electrical energy, the penetration of renewable energy sources in existing electricity infrastructure is expected to increase significantly within the next few years. The solid state transformer (SST) is expected to play an essential role in future smart grid topologies. Unlike traditional magnetic transformer, SST is flexible enough to be of modular construction, enabling bi-directional power flow and can be employed for AC and DC grids. Moreover, SSTs can control the voltage level and modulate both active and reactive power at the point of common coupling without the need to external flexible AC transmission system device as per the current practice in conventional electricity grids. The rapid advancement in power semiconductors switching speed and power handling capacity will soon allow for the commercialisation of grid-rated SSTs. This paper is aimed at introducing a state-of-the-art review for SST proposed topologies, controllers, and applications. Additionally, strengths, weaknesses, opportunities, and threats (SWOT) analysis along with a brief review of market drivers for prospective commercialisation are elaborated. Full article

(This article belongs to the Special Issue Advanced Power Conversion Technologies)

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