Electronics

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14 pages, 2665 KiB

Open AccessArticle

Dynamic Sliding Mode Control of DC-DC Converter to Extract the Maximum Power of Photovoltaic System Using Dual Sliding Observer

by Ali Karami-Mollaee and Oscar Barambones

Electronics 2022, 11(16), 2506; https://doi.org/10.3390/electronics11162506 - 11 Aug 2022

Cited by 8 | Viewed by 1568

Abstract

This paper concerns the maximum power extraction of a photovoltaic generator system (PGS). The PGS consists of single photovoltaic (PV) cells. To improve the efficiency of a PGS, it is necessary to work within its maximum power point (MPP). In a PGS, output [...] Read more.

This paper concerns the maximum power extraction of a photovoltaic generator system (PGS). The PGS consists of single photovoltaic (PV) cells. To improve the efficiency of a PGS, it is necessary to work within its maximum power point (MPP). In a PGS, output power is dependent on solar irradiance and the operating temperature and, therefore, MPP would be varied. To address this problem, a converter should be placed after the PGS and a smooth control signal should be used to adjust its duty cycle. The other challenge of a total system, i.e., PGS and converter, is the uncertainty involved. To overcome this uncertainty, a dynamic sliding mode control (SMC) can be used to regulate the smooth duty cycle. The low-pass integrator before the system can remove the chattering in dynamic SMC. However, due to the integrator, the states of the system increase and, hence, we propose a dual sliding observer (DSO) to estimate this added state. For a reliable comparison with the conventional SMC, the same proposed DSO can be applied in both dynamic and conventional SMC. The provided comparison shows the effectiveness of dynamic SMC in chattering suppression and real implementation with respect to conventional SMC. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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23 pages, 13318 KiB

Open AccessArticle

Improving the Inertial Response of a Grid-Forming Voltage Source Converter

by Juan Dolado, Jose Luis Rodríguez Amenedo, Santiago Arnaltes and Joaquín Eloy-Garcia

Electronics 2022, 11(15), 2303; https://doi.org/10.3390/electronics11152303 - 23 Jul 2022

Cited by 7 | Viewed by 2465

Abstract

In recent years, the use of synchronous generators (SGs) has been displaced due to the increased use of renewable energy sources. These types of plants mostly use power electronic converters to connect to power grids, which, due to their mode of operation, cannot [...] Read more.

In recent years, the use of synchronous generators (SGs) has been displaced due to the increased use of renewable energy sources. These types of plants mostly use power electronic converters to connect to power grids, which, due to their mode of operation, cannot provide the same services. This paper analyzes the synchronization of Grid-Forming converters (GFM) without phase-locked loop (PLL) through the active power control loop. Stability analysis shows that when increasing the emulated moment of inertia in a voltage source converter (VSC) using grid-forming control, the system becomes oscillatory. The paper proposes a novel compensation mechanism in order to damp the system oscillation, allowing the implementation of inertia emulation. Finally, the real-time implementation is executed using a Hardware in the Loop experimental set-up. The response of VSC under grid disturbances is simulated in a real time simulator, while the proposed control system is implemented in a real-time controller platform. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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25 pages, 8823 KiB

Open AccessArticle

Detailed Power Loss Analysis of T-Type Neutral Point Clamped Converter for Reactive Power Compensation

by Marcin Zygmanowski

Electronics 2022, 11(14), 2129; https://doi.org/10.3390/electronics11142129 - 7 Jul 2022

Cited by 3 | Viewed by 2497

Abstract

The paper presents an analysis of power losses in a three-phase T-type neutral point clamped converter with insulated gate bipolar transistors. The paper’s main aim is to perform a detailed analysis of power losses in the converter operating as an active power filter. [...] Read more.

The paper presents an analysis of power losses in a three-phase T-type neutral point clamped converter with insulated gate bipolar transistors. The paper’s main aim is to perform a detailed analysis of power losses in the converter operating as an active power filter. The study is based on the use of characteristics of semiconductor devices provided by the manufacturer in the module datasheet. Thanks to the analysis, it is possible to recognise the value of power losses, which facilitates the design of the converter cooling system. Identifying how power losses are distributed between the module switching devices is also possible. Power losses are shown as functions of the output current and module temperature. The analysis results were successfully verified by measuring power losses using a laboratory model of the converter with rated currents of 10 and 20 A. The obtained results indicate relatively low power losses and a relatively even distribution of power losses between the semiconductor devices. This is a superior feature of the three-level T-type neutral point clamped converter topology. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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18 pages, 2982 KiB

Open AccessArticle

A Fault Clearance and Restoration Approach for MMC-Based MTDC Grid

by Mohammed Alharbi, Semih Isik, Faris E. Alfaris, Abdulaziz Alkuhayli and Subhashish Bhattacharya

Electronics 2022, 11(14), 2127; https://doi.org/10.3390/electronics11142127 - 7 Jul 2022

Cited by 2 | Viewed by 2155

Abstract

With the growth in continuous energy demand, high-voltage Multi-Terminal DC (MTDC) systems are technically and economically feasible to transmit bulk power and integrate additional energy sources. However, the high vulnerability of the MTDC systems to DC faults, especially pole-to-pole (P2P) faults, is technically [...] Read more.

With the growth in continuous energy demand, high-voltage Multi-Terminal DC (MTDC) systems are technically and economically feasible to transmit bulk power and integrate additional energy sources. However, the high vulnerability of the MTDC systems to DC faults, especially pole-to-pole (P2P) faults, is technically challenging. The development of DC fault ride-through techniques such as DC circuit breakers is still challenging due to their high cost and complex operation. This paper presents the DC fault clearance and isolation method for an MMC-based MTDC grid without adopting the high-cost DC circuit breakers. Besides, a restoration sequence is proposed to re-energize the DC grid upon clearing the fault. An MMC-based four-terminal DC grid is implemented in a Control-Hardware-in-Loop (CHIL) environment based on Xilinx Virtex-7 FPGAs and Real-Time Digital Simulator (RTDS). The RTDS results show that the MTDC system satisfactorily rides through DC faults and can safely recover after DC faults. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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19 pages, 11394 KiB

Open AccessArticle

Performance Assessment of Mismatch Mitigation Methodologies Using Field Data in Solar Photovoltaic Systems

by Kamran Ali Khan Niazi, Tamas Kerekes, Alberto Dolara, Yongheng Yang and Sonia Leva

Electronics 2022, 11(13), 1938; https://doi.org/10.3390/electronics11131938 - 21 Jun 2022

Cited by 3 | Viewed by 2083

Abstract

Partial shading and other non-ideal conditions cause electrical mismatches that reduce the output power generated by a photovoltaic (PV) system. It affects the overall performance and efficiency of PV systems. Therefore, a model is developed in MATLAB, which analyses the performance of the [...] Read more.

Partial shading and other non-ideal conditions cause electrical mismatches that reduce the output power generated by a photovoltaic (PV) system. It affects the overall performance and efficiency of PV systems. Therefore, a model is developed in MATLAB, which analyses the performance of the PV systems under real irradiance profiles and temperatures for various available mismatch mitigation methodologies, i.e., bypass diode, DC power optimizer, and differential power processing (DPP). More specifically, this study will help to understand the best mismatch reduction methodologies for a solar PV system under different scenarios. The results also are validated by comparing them with a similar PV system installed in SolarTech^LAB, which also operates under the same irradiance and temperature conditions under which these models are tested. This study also presents novel results, covering discussions on the reverse voltage distribution under mismatch scenarios among bypass diode, DC power optimizer, and DPP techniques. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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18 pages, 4275 KiB

Open AccessArticle

Optimal Coordinated Control Strategy of Clustered DC Microgrids under Load-Generation Uncertainties Based on GWO

by Zaid Hamid Abdulabbas Al-Tameemi, Tek Tjing Lie, Gilbert Foo and Frede Blaabjerg

Electronics 2022, 11(8), 1244; https://doi.org/10.3390/electronics11081244 - 14 Apr 2022

Cited by 4 | Viewed by 2062

Abstract

The coordination of clustered microgrids (MGs) needs to be achieved in a seamless manner to tackle generation-load mismatch among MGs. A hierarchical control strategy based on PI controllers for local and global layers has been proposed in the literature to coordinate DC MGs [...] Read more.

The coordination of clustered microgrids (MGs) needs to be achieved in a seamless manner to tackle generation-load mismatch among MGs. A hierarchical control strategy based on PI controllers for local and global layers has been proposed in the literature to coordinate DC MGs in a cluster. However, this control strategy may not be able to resist significant load disturbances and unexpected generated powers due to the sporadic nature of the renewable energy resources. These issues are inevitable because both layers are highly dependent on PI controllers who cannot fully overcome the abovementioned obstacles. Therefore, Grey Wolf Optimizer (GWO) is proposed to enhance the performance of the global layer by optimizing its PI controller parameters. The simulation studies were conducted using the well-established MATLAB Simulink, and the results reveal that the optimized global layer performs better than the conventional ones. It is noticed that not only accurate power-sharing and proper voltage regulation within ±1% along with fewer power losses are achieved by adopting the modified consensus algorithm for the clustered DC MGs, but also the settling time and overshoot/undershoot are reduced even with the enormous load and generation changes which indicates the effectiveness of the proposed method used in the paper. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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42 pages, 26793 KiB

Open AccessArticle

Prototyping Power Electronics Systems with Zynq-Based Boards Using Matlab/Simulink—A Complete Methodology

by Luís Caseiro, Diogo Caires and André Mendes

Electronics 2022, 11(7), 1130; https://doi.org/10.3390/electronics11071130 - 2 Apr 2022

Cited by 5 | Viewed by 5047

Abstract

Many advanced power electronics control techniques present a steep computational load, demanding advanced controllers, such as FPGAs. However, FPGA development is a daunting and time-consuming task, inaccessible to most users. This paper proposes a complete methodology for prototyping power electronics with Xilinx Zynq-based [...] Read more.

Many advanced power electronics control techniques present a steep computational load, demanding advanced controllers, such as FPGAs. However, FPGA development is a daunting and time-consuming task, inaccessible to most users. This paper proposes a complete methodology for prototyping power electronics with Xilinx Zynq-based boards using Matlab/Simulink and HDL Coder. Even though these tools are relatively well documented, and several works in the literature have used them, a methodology for developing power electronics systems with them has never been proposed. This paper aims to address that, by proposing a complete programming and design methodology for Zynq-based power electronics and discussing important drawbacks and hurdles in Simulink/HDL Coder development, as well as their possible solutions. In addition, techniques for the implementation of all required peripherals (ADCs, digital outputs, etc.), system protections, and real-time data acquisition on Zynq boards are presented. This methodology considerably reduces the development time and effort of power electronics solutions using Zynq-based boards. In addition, a demonstration Simulink model is provided with all proposed techniques and protections, for use with a readily available development board (Zedboard) and ADC modules. This should further reduce the learning curve and development effort of this type of solution, contributing to a broader access to high-performance control prototyping using Zynq-based platforms. An application example is presented to demonstrate the potential of the proposed workflow, using a Zedboard to control a multilevel UPS inverter prototype with Model Predictive Control. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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20 pages, 3056 KiB

Open AccessArticle

A Comparative Analysis of Soft Switching Techniques in Reducing the Energy Loss and Improving the Soft Switching Range in Power Converters

by Ratil H. Ashique, Zainal Salam, Md. Hasan Maruf, ASM Shihavuddin, Md. Tariqul Islam, Md. Fayzur Rahman, Panos Kotsampopoulos and Hady H. Fayek

Electronics 2022, 11(7), 1062; https://doi.org/10.3390/electronics11071062 - 28 Mar 2022

Cited by 8 | Viewed by 4053

Abstract

This paper presents a comparative analysis of the zero-voltage zero-current switching (ZVZCS) soft switching technique with zero-voltage switching (ZVS) and zero-current switching (ZCS) counterparts. The generalization of the voltage–current crossover or the energy loss factor obtained from simulation of the prototype converter shows [...] Read more.

This paper presents a comparative analysis of the zero-voltage zero-current switching (ZVZCS) soft switching technique with zero-voltage switching (ZVS) and zero-current switching (ZCS) counterparts. The generalization of the voltage–current crossover or the energy loss factor obtained from simulation of the prototype converter shows that the ZVZCS significantly reduces the losses and helps to improve the efficiency of the converter as compared to the ZVS or the ZCS. On the other hand, it is also found that the soft switching range of operation of the ZVS and the ZCS is largely affected by the maximum switch voltage and switch current, respectively. In contrast, these factors have a negligible effect on the ZVZCS operation which results in an extended range of soft switching operation. Additionally, a detailed PSPICE simulation is performed for selected ZVS, ZCS, and ZVZCS topologies from the recent literature, and the switching losses in the main switches of the converters are measured. It is observed that the energy losses in the ZVZCS mode are reduced on average by approximately 26% at turn on and 20% at turn off as compared to the ZVS and the ZCS. Furthermore, the low standard deviation in this mode confirms a stable low-loss profile which renders an extended soft switching range. An experimental test is also conducted by building the prototype converter to verify the simulation results. It is found that the switching losses are minimum while the converter is operated in the ZVZCS mode. Additionally, the efficiency drop remains consistently low as compared to the ZVS and the ZCS in the whole operating range. Accordingly, the simulation and the experimental results are both found to be consistent. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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15 pages, 2764 KiB

Open AccessFeature PaperArticle

An Overall Analysis of the Static Characteristics of the Single Active Bridge Converter

by Alberto Rodriguez, Javier Sebastian, Diego G. Lamar, Marta M. Hernando, Iban Ayarzaguena, Igor Larrazabal, David Ortega, Jose M. Bermejo and Francisco Vazquez

Electronics 2022, 11(4), 601; https://doi.org/10.3390/electronics11040601 - 15 Feb 2022

Cited by 6 | Viewed by 2661

Abstract

The dual active bridge (DAB) converter has been extensively analyzed and used in recent years for applications where bidirectional power flow is required. The unidirectional version of the DAB, which replaces the active output bridge with a diode bridge, has been called the [...] Read more.

The dual active bridge (DAB) converter has been extensively analyzed and used in recent years for applications where bidirectional power flow is required. The unidirectional version of the DAB, which replaces the active output bridge with a diode bridge, has been called the single active bridge (SAB). The static behavior of the SAB differs markedly from similar DC/DC converters and can provide interesting advantages in certain applications. This paper presents a thorough study of the static behavior of the single active bridge (SAB) converter in different conduction modes. This study focuses on the description of the conduction modes, marking the main differences compared to similar DC/DC converters. Moreover, the SAB can be designed to operate in conduction mode for a given power level with different performance. A design guide is proposed, and the performance of different designs are compared, quantifying current stresses in the semiconductors. Finally, the main contribution of this paper is the identification of the similarities and differences between the SAB and the buck, forward, and phase-shifted full-bridge converters. It should be noted that the position of the inductor, either before or after the output rectifier bridge, modifies the voltage withstood by the output diodes and depends on the conduction mode, the voltage conversion ratio of the converter, and consequently, its main operation and performance. Moreover, the operation of the SAB is similar to a current source in all conduction modes, and it is not usual in similar converters. This peculiar behavior can be useful in certain applications. The theoretical study, the different designs, and the predicted operation of the SAB in different conduction modes have been validated using simulation and experimental results. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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15 pages, 51430 KiB

Open AccessCommunication

Analytical Expression for Line Voltage THD of Three-Phase Staircase Modulated Multilevel Inverters

by Eli Barbie, Dmitry Baimel and Alon Kuperman

Electronics 2022, 11(3), 364; https://doi.org/10.3390/electronics11030364 - 25 Jan 2022

Cited by 1 | Viewed by 2091

Abstract

In this article, a simple closed-form analytical expression for the line-voltage total harmonic distortion (LTHD) of three-phase staircase-modulated (SCM) multilevel inverters (MLI) is proposed. The revealed expression is valid for any conventional MLI topology with arbitrary number and parity of voltage levels. The [...] Read more.

In this article, a simple closed-form analytical expression for the line-voltage total harmonic distortion (LTHD) of three-phase staircase-modulated (SCM) multilevel inverters (MLI) is proposed. The revealed expression is valid for any conventional MLI topology with arbitrary number and parity of voltage levels. The proposed formulation is presented as an analytic function of the number of voltage levels (N) and the phase switching angles (PSA); thus, it is suited to MLIs of equal voltage source supply and of any topology. This function may be employed for accurate LTHD calculation and optimization. The results are verified against LTHD calculations and optimizations, obtained numerically from previous works. Both processor in loop (PIL)- and controller + hardware in loop (C-HIL)-based real-time experimental validations are included as well. A downloadable file containing the Maple and MATLAB functions of the proposed expression are also provided. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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12 pages, 1679 KiB

Open AccessFeature PaperArticle

The Impact of Overlap Period on the Stability of Current-Controlled Alternate Arm Converter Based on dq Frame Impedance Analysis

by Shan Jiang, Felipe Arraño-Vargas, Zhiwei Shen and Georgios Konstantinou

Electronics 2022, 11(3), 301; https://doi.org/10.3390/electronics11030301 - 19 Jan 2022

Cited by 1 | Viewed by 1935

Abstract

As a variant modular converter configuration, the alternate arm converter (AAC) is well-suited for high-voltage power transmission and large-scale integration of renewables. In contrast to conventional multilevel converters, the director switches in the arms of AAC lead to the introduction of an overlap [...] Read more.

As a variant modular converter configuration, the alternate arm converter (AAC) is well-suited for high-voltage power transmission and large-scale integration of renewables. In contrast to conventional multilevel converters, the director switches in the arms of AAC lead to the introduction of an overlap period, during which circuiting current can flow through the two arms in the same phase. Thus, fixed or variable overlap period control can be implemented in AAC systems so as to dynamically balance stored arm energy. However, the control of overlap period is linked to instability issues that might impede the safe operation of AAC systems, which are yet to be reported. In this paper, the stability of an AAC system is demonstrated based on measured grid and converter impedance, in conjunction with impedance-based stability criterion in the

d q

frame. The interaction between harmonic sources at AC and DC sides of the AAC system is analyzed to determine resonant frequencies in the AC current when any potential resonance is identified in the

d q

frame. Novel results with respect to the impact of overlap period on the system stability are obtained by depicting and comparing the Eigenloci in the polar plot, which are validated by real-time simulations. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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19 pages, 5979 KiB

Open AccessArticle

A High-Gain Multiphase Interleaved Differential Capacitor Clamped Boost Converter

by Dogga Raveendhra, Poojitha Rajana, Kalamchety Srinivasa Ravi Kumar, Praveen Jugge, Ramesh Devarapalli, Eugen Rusu and Hady H. Fayek

Electronics 2022, 11(2), 264; https://doi.org/10.3390/electronics11020264 - 14 Jan 2022

Cited by 5 | Viewed by 2557

Abstract

A step-up for a non-isolated interleaved differential capacitor clamped boost (IDCCB) DC–DC converter is proposed in this manuscript. Because of its ability to produce high voltage gains, it is used in high-power applications. This converter’s modelling and control design are applicable to any [...] Read more.

A step-up for a non-isolated interleaved differential capacitor clamped boost (IDCCB) DC–DC converter is proposed in this manuscript. Because of its ability to produce high voltage gains, it is used in high-power applications. This converter’s modelling and control design are applicable to any number of phases. A six-phase interleaved differential capacitor clamped boost prototype is tested in this work, with an input voltage of 60 V, an output voltage of 360 V, and a nominal output power of 2.2 kW. The components of the converter are placed and controlled in such a way that the output voltage is the sum of the two capacitor voltages and the input voltage, which is two times higher than the supply voltage when compared to a conventional interleaved differential dual-boost converter. This converter reduces the stress on the capacitor with reference to the conventional interleaved differential boost converter for the same conversion gain. This prototype is considered and the developed approach is applied, after which the experimental results are obtained. This converter has potential for application in areas such as renewable energy conversion and electric vehicles. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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19 pages, 4861 KiB

Open AccessArticle

Smooth-Transition Simple Digital PWM Modulator for Four-Switch Buck-Boost Converters

by Miguel Fernandez, Alberto Rodriguez, Miguel Rodríguez, Aitor Vazquez, Pablo Fernandez and Manuel Arias

Electronics 2022, 11(1), 100; https://doi.org/10.3390/electronics11010100 - 29 Dec 2021

Cited by 6 | Viewed by 3110

Abstract

This paper proposes a simple, hardware-efficient digital pulse width modulator for a 4SBB that enables operation in Buck, Boost, and Buck+Boost modes, achieving smooth transitions between the different modes. The proposed modulator is simulated using Simulink and experimentally demonstrated using a 500 W [...] Read more.

This paper proposes a simple, hardware-efficient digital pulse width modulator for a 4SBB that enables operation in Buck, Boost, and Buck+Boost modes, achieving smooth transitions between the different modes. The proposed modulator is simulated using Simulink and experimentally demonstrated using a 500 W 4SBB converter with 24 V input voltage and 12–36 V output voltage range. Full article

(This article belongs to the Special Issue Power Converter Design, Control and Applications)

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