Energies

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18 pages, 12113 KiB

Open AccessArticle

Practical Dead-Time Control Methodology of a Three-Phase Dual Active Bridge Converter for a DC Grid System

by Hyun-Jun Choi, Jung-Hoon Ahn, Jee-Hoon Jung and Sung-Geun Song

Energies 2023, 16(22), 7679; https://doi.org/10.3390/en16227679 - 20 Nov 2023

Viewed by 860

An effective dead-time control strategy for the three-phase dual active bridge (3P-DAB) converter of a distribution system is studied to reduce the switching losses of power switches and improve the under-light-load power conversion efficiency. Because of the advantages of a dual-active bridge converter, [...] Read more.

An effective dead-time control strategy for the three-phase dual active bridge (3P-DAB) converter of a distribution system is studied to reduce the switching losses of power switches and improve the under-light-load power conversion efficiency. Because of the advantages of a dual-active bridge converter, such as an inherent zero-voltage switching (ZVS) capability without any additional resonant tank and a seamless bi-directional power transition, this is an attractive topology for bi-directional application. The 3P-DAB converter is apt for high-power applications such as aircraft due to an interleaved structure, which can reduce conduction losses. However, the design of the dead time depends on engineering experience and empirical methods. In order to overcome the conventional practicality of the dead-time design method, the effective control of dead time is proposed based on the theoretical analysis. In this paper, the overall explanation of the 3P-DAB converter is shown with operation principles. In addition, the dead-time effect of the 3P-DAB converter is examined and the practical variable dead-time control strategy is studied. Finally, experimental results validate the proposed variable dead-time control strategy using a 25 kW prototype 3P-DAB converter. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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15 pages, 6835 KiB

Open AccessArticle

Development and Control of a Switched Capacitor Multilevel Inverter

by Safwan Mustafa, Adil Sarwar, Mohd Tariq, Shafiq Ahmad and Haitham A. Mahmoud

Energies 2023, 16(11), 4269; https://doi.org/10.3390/en16114269 - 23 May 2023

Cited by 2 | Viewed by 1295

Abstract

This article offers a novel boost inverter construction with a Nine-level quadruple voltage boosting waveform. The primary drawback of conventional MLI is the need for a high voltage DC-DC converter to increase the voltage when using renewable energy sources. Consequently, the developed method, [...] Read more.

This article offers a novel boost inverter construction with a Nine-level quadruple voltage boosting waveform. The primary drawback of conventional MLI is the need for a high voltage DC-DC converter to increase the voltage when using renewable energy sources. Consequently, the developed method, complete with a quadruple voltage boost ability, can alleviate that shortcoming by automatically increased the incoming voltage. A single DC source, two switching capacitors, and eleven switches are all that are used in the newly presented architecture. The voltage of the capacitor automatically balances. The switched capacitor MLI is distinguished by the fewer parts that are required and the substitution of a capacitor for a DC source. The switching capacitor has to be charged and discharged properly in order to produce the nine-level output voltage waveform. The SPSC unit makes these levels attainable. To achieve voltage boosting, switched capacitors are coupled in parallel and series in the conduction channel. The quality of this proposed topology has been analyzed through different parameters based on the components count, THD, and cost; the resulting efficiency reaches 97.85%. The switching order of the proposed method has been controlled by the Nearest Level Modulation Method (NLC). MATLAB and PLECS software were used to evaluate the constructed Nine-level converter. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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14 pages, 4620 KiB

Open AccessArticle

Analysis of a Single-Phase Transformerless Bidirectional PFC

by Mei Liang, Pengyu Jia and Tengfei Guo

Energies 2022, 15(22), 8329; https://doi.org/10.3390/en15228329 - 08 Nov 2022

Viewed by 1436

Abstract

This paper presents a single-phase transformerless bidirectional power factor corrector (PFC). A capacitor is inserted into a conventional full-bridge PFC by connecting the ac line terminal and a terminal of DC voltage. The functions of this inserted capacitor have two roles: to bypass [...] Read more.

This paper presents a single-phase transformerless bidirectional power factor corrector (PFC). A capacitor is inserted into a conventional full-bridge PFC by connecting the ac line terminal and a terminal of DC voltage. The functions of this inserted capacitor have two roles: to bypass the common-mode leakage current from the stray capacitor; to form an LCL filter to reduce the inductor current ripple. A hybrid modulation method is employed in this PFC. The unipolar switching scheme is applied to modulate the PFC, which can achieve high efficiency. Meanwhile, an additional modulation is inserted into the blank time of low-frequency switches to decrease the changing speed of the voltage on the inserted capacitor, and to decrease the spike on the inductor current and leakage current. The performance of the PFC is experimentally verified using a 5 kW prototype. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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17 pages, 7141 KiB

Open AccessArticle

Design and Control of a Quasi-Z Source Multilevel Inverter Using a New Reaching Law-Based Sliding Mode Control

by Muhammad Awais Rafiq, Abasin Ulasyar, Waqar Uddin, Haris Sheh Zad, Abraiz Khattak and Kamran Zeb

Energies 2022, 15(21), 8002; https://doi.org/10.3390/en15218002 - 27 Oct 2022

Cited by 4 | Viewed by 1666

Abstract

The rapid growth in renewable energies has given rise to their integration into the grid system. These renewable and clean energy sources are dependent on external conditions such as wind speed, solar irradiation, and temperature. For a stable connection between these sources and [...] Read more.

The rapid growth in renewable energies has given rise to their integration into the grid system. These renewable and clean energy sources are dependent on external conditions such as wind speed, solar irradiation, and temperature. For a stable connection between these sources and power grid systems, a controller is necessary to regulate the system’s closed-loop dynamic behavior. A sliding mode control (SMC) using a new reaching law is proposed for the integration of a Modified Capacitor-Assisted Extended Boost (MCAEB) quasi-Z Source 7 level 18 switch inverter with the grid. An SMC-based controller was implemented to regulate the current flow between the inverter and the grid. SMC has the advantages of ease of implementation, robustness, and invariance to disturbance. The simulation results of SMC and the proportional integral (PI) controller are compared in terms of settling time, steady-state error, and total harmonic distortion (THD) during transient response, steady-state response and step response under different operating conditions. A hardware-in-loop (HIL)-based experimental setup of MCAEB quasi-Z source multilevel inverter was implemented using OPAL-RT. The performance of the proposed controller was further validated by implementing it on DSPACE-1202. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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18 pages, 4876 KiB

Open AccessArticle

An DPWM for Active DC-Link Type Quasi-Z-Source Inverter to Reduce Component Voltage Rating

by Duc-Tri Do, Vinh-Thanh Tran and Khai Nguyen

Energies 2022, 15(13), 4889; https://doi.org/10.3390/en15134889 - 04 Jul 2022

Cited by 2 | Viewed by 1427

Abstract

The conventional DC-link type quasi-Z-source inverter has been known as a buck–boost inverter with a low component voltage rating. This paper proposes an active DC-link type quasi-Z-source inverter by adding one active switch and one diode to the impedance-source network to enhance the [...] Read more.

The conventional DC-link type quasi-Z-source inverter has been known as a buck–boost inverter with a low component voltage rating. This paper proposes an active DC-link type quasi-Z-source inverter by adding one active switch and one diode to the impedance-source network to enhance the voltage gain of the inverter. As a result, the component voltage rating of the inverter is significantly reduced, which is demonstrated through some comparisons between the proposed topology and others. A discontinuous pulse width modulation (DPWM) scheme is proposed to control the inverter, which reduces the number of commutations compared to the traditional strategy. Under this approach, the insertion of a shoot-through state does not cause any extra commutations compared to the conventional voltage-source inverter. Details about control implementation, steady-state analysis, and design guidelines are also presented in this paper. Simulation and a laboratory prototype have been built to test the proposed inverter. Both buck and boost operations of the proposed inverter are implemented to validate the performance of the inverter. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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21 pages, 2872 KiB

Open AccessArticle

An Adaptive Hybrid Control of Grid Tied Inverter for the Reduction of Total Harmonic Distortion and Improvement of Robustness against Grid Impedance Variation

by Tila Muhammad, Adnan Umar Khan, Muhammad Tajammal Chughtai, Reyyan Ahmad Khan, Yousra Abid, Muhammad Islam and Sheroz Khan

Energies 2022, 15(13), 4724; https://doi.org/10.3390/en15134724 - 28 Jun 2022

Cited by 3 | Viewed by 1444

Abstract

Background: Grid-tied inverters play an efficient role in the integration of renewable energy resources with utility grids. Motivation: However, the interconnection between power converters and the grid has been seen to be responsible for various stability issues such as weak grid, and under [...] Read more.

Background: Grid-tied inverters play an efficient role in the integration of renewable energy resources with utility grids. Motivation: However, the interconnection between power converters and the grid has been seen to be responsible for various stability issues such as weak grid, and under weak grid conditions the injection of power to the grid becomes a challenging task due to continuously varying grid impedance affecting the stability margins as a result. Additionally, the grid impedance-related issues boost the voltage harmonics which further devalue its performance. These voltage harmonics propagate through the Phase-Locked Loop (PLL) circuit to the control unit of the inverter which in turn amplifies the low order harmonics of the inverter. Method: The aim of this research is to introduce a novel strategy that decreases the effect of grid impedance-variations on the performance and stability of an inverter. Hence, an adaptive hybrid mode control technique consisting of two parts is proposed in this research. The current regulator part is implemented in a synchronous reference frame for its gain and time parameters to improve the performance, stability, and response time. The adaptive harmonic compensators are implemented in a stationary reference frame for harmonic compensation purposes. This adaptive nature of harmonic compensator can effectively work in the case of frequency variation where the fixed value based harmonic compensator fails. Results: The adaptive harmonic compensators improve the performance by reducing total harmonic distortion (THD), reduce computation and improve stability when the grid has distorted voltage, variation in grid impedance and frequency. Impact and utility: Our results show that the system becomes less sensitive to grid impedance variations which makes the proposed technique very relevant to the stability performance applications. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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18 pages, 28986 KiB

Open AccessArticle

Power Ripple Control Method for Modular Multilevel Converter under Grid Imbalances

by Mohammed Alharbi, Semih Isik, Abdulaziz Alkuhayli and Subhashish Bhattacharya

Energies 2022, 15(10), 3535; https://doi.org/10.3390/en15103535 - 12 May 2022

Cited by 6 | Viewed by 1742

Abstract

Modular multilevel converters (MMCs) are primarily adopted for high-voltage applications, and are highly desired to be operated even under fault conditions. Researchers focused on improving current controllers to reduce the adverse effects of faults. Vector control in the DQ reference domain is generally [...] Read more.

Modular multilevel converters (MMCs) are primarily adopted for high-voltage applications, and are highly desired to be operated even under fault conditions. Researchers focused on improving current controllers to reduce the adverse effects of faults. Vector control in the DQ reference domain is generally adopted to control the MMC applications. Under unstable grid conditions, it is challenging to control double-line frequency oscillations in the DQ reference frame. Therefore, active power fluctuations are observed in the active power due to the uncontrolled AC component’s double line frequency component. This paper proposes removing the active power’s double-line frequency under unbalanced grid conditions during DQ transformation. Feedforward and feedback control methods are proposed to eliminate ripple in active power under fault conditions. An extraction method for AC components is also proposed for the power ripple control to eliminate the phase error occurring with the conventional high-pass filters. The system’s stability with the proposed controller is tested and compared with a traditional MMC controller using the Nyquist stability criterion. A real-time digital simulator (RTDS) and Xilinx Virtex 7-based FPGA were used to verify the proposed control methods under single-line-to-ground (SLG) faults. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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23 pages, 37412 KiB

Open AccessArticle

Adoption Pathways for DC Power Distribution in Buildings

by Vagelis Vossos, Daniel L. Gerber, Melanie Gaillet-Tournier, Bruce Nordman, Richard Brown, Willy Bernal Heredia, Omkar Ghatpande, Avijit Saha, Gabe Arnold and Stephen M. Frank

Energies 2022, 15(3), 786; https://doi.org/10.3390/en15030786 - 21 Jan 2022

Cited by 18 | Viewed by 2915

Abstract

Driven by the proliferation of DC energy sources and DC end-use devices (e.g., photovoltaics, battery storage, solid-state lighting, and consumer electronics), DC power distribution in buildings has recently emerged as a path to improved efficiency, resilience, and cost savings in the transitioning building [...] Read more.

Driven by the proliferation of DC energy sources and DC end-use devices (e.g., photovoltaics, battery storage, solid-state lighting, and consumer electronics), DC power distribution in buildings has recently emerged as a path to improved efficiency, resilience, and cost savings in the transitioning building sector. Despite these important benefits, there are several technological and market barriers impeding the development of DC distribution, which have kept this technology at the demonstration phase. This paper identifies specific end-use cases for which DC distribution in buildings is viable today. We evaluate their technology and market readiness, as well as their efficiency, cost, and resiliency benefits while addressing implementation barriers. The paper starts with a technology review, followed by a comprehensive market assessment, in which we analyze DC distribution field deployments and their end-use characteristics. We also conduct a survey of DC power and building professionals through on-site visits and phone interviews and summarize lessons learned and recommendations. In addition, the paper includes a novel efficiency analysis, in which we quantify energy savings from DC distribution for different end-use categories. Based on our findings, we present specific adoption pathways for DC in buildings that can be implemented today, and for each pathway we identify challenges and offer recommendations for the research and building community. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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20 pages, 17197 KiB

Open AccessArticle

A Transformerless AC-AC Converter with Improved Power Quality Employed to Step-Down Power Frequency at Output

by Naveed Ashraf, Ghulam Abbas, Nasim Ullah, Ahmad Aziz Al-Ahmadi, Abdul Rehman Yasin, Ahmed Bilal Awan and Mohsin Jamil

Energies 2022, 15(2), 667; https://doi.org/10.3390/en15020667 - 17 Jan 2022

Cited by 6 | Viewed by 2820

Abstract

Variable voltage and frequency are required to govern the torque-speed characteristics of many industrial drive systems. Traditionally, this is achieved with a power converting system implemented with multistage converters. This technology is based on rectifying AC power into DC and then DC into [...] Read more.

Variable voltage and frequency are required to govern the torque-speed characteristics of many industrial drive systems. Traditionally, this is achieved with a power converting system implemented with multistage converters. This technology is based on rectifying AC power into DC and then DC into AC with an inverter circuit. The power quality concerns of both conversion stages are tackled by selecting high switching frequency PWM control and harmonics mitigation filters. Also, using a bulky DC-link capacitor is one of the big sources of low system reliability, so this approach increases the conversion losses, circuit, and control complications. The frequency step-down conversion is very attractive with direct AC-AC converters as it has a simple control and circuit structure, but these converters face poor power quality challenges once the output frequency is decreased with respect to an input. In these converters, the total harmonic distortion (THD) of the output voltage becomes very poor once the output frequency is reduced. The problem of high THD of the output is addressed in the power converting circuits implemented with line frequency multi-winding transformers. The required number of output winding and switching devices (diodes and thyristors) increases once the value of the output frequency is decreased. This will increase the overall volume, cost, and losses. The use of a bulky and costly line frequency transformer may be eliminated if AC voltage controllers have non-inverted and inverted voltage buck capabilities, such existing topologies either have complex control schemes or require a large number of operating devices. Therefore, in this research article, a new transformerless frequency step-down converter employing fewer devices is proposed. This approach is realized with a high-frequency controlled rectifier for the required voltage stabilization and a low-frequency inverter bridge for frequency control. Its validation is supported by the results attained from Simulink and practical-based prototypes. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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17 pages, 24807 KiB

Open AccessArticle

Optimized Modulation Method for Common-Mode Voltage Reduction in H7 Inverter

by Belete Belayneh Negesse, Chang-Hwan Park, Seung-Hwan Lee, Seon-Woong Hwang and Jang-Mok Kim

Energies 2021, 14(19), 6409; https://doi.org/10.3390/en14196409 - 07 Oct 2021

Cited by 1 | Viewed by 1486

Abstract

The three-phase H7 inverter topology installs an additional power semiconductor switch to the positive or negative node of the DC-link for reducing the common-mode voltage (CMV) by disconnecting the inverter from the DC source during the zero-voltage vectors. The conventional CMV reduction method [...] Read more.

The three-phase H7 inverter topology installs an additional power semiconductor switch to the positive or negative node of the DC-link for reducing the common-mode voltage (CMV) by disconnecting the inverter from the DC source during the zero-voltage vectors. The conventional CMV reduction method for the three-phase H7 inverter uses modified discontinuous pulse width modulation (MDPWM) and generates a switching signal for the additional switch using logical operations. However, the conventional method is unable to eliminate the CMV for the entire dwell time of the zero-voltage vectors. It only has the effect of reducing the CMV in a limited area of the space vector where the

V_{7}

zero voltage vector is applied. Therefore, this paper proposes an optimized modulation method that can reduce the CMV during the entire dwell time of zero-voltage vectors. The proposed method moves the switching patterns by adding an offset voltage to guarantee that only one kind of zero-voltage vector,

V_{7}

, is applied in the system. It then turns off the seventh switch only during the zero-voltage vector to disconnect the inverter from the DC source. As a result, the CMV and the leakage current are attenuated for the entire dwell time of the zero-voltage vector. Simulation and experimental results confirm the validity of the proposed method. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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21 pages, 4704 KiB

Open AccessArticle

Implementation of a Resonant Converter with Topology Morphing to Achieve Bidirectional Power Flow

by Bor-Ren Lin

Energies 2021, 14(16), 5186; https://doi.org/10.3390/en14165186 - 22 Aug 2021

Cited by 3 | Viewed by 1469

Abstract

A DC converter with the benefits of reverse power capability, less switching loss and wide voltage operation is presented and implemented for wide input voltage applications such as fuel cell energy, photovoltaic (PV) system and DC wind power. Two full bridge resonant circuits [...] Read more.

A DC converter with the benefits of reverse power capability, less switching loss and wide voltage operation is presented and implemented for wide input voltage applications such as fuel cell energy, photovoltaic (PV) system and DC wind power. Two full bridge resonant circuits are used in the presented converter to achieve bidirectional power flow capability and reduce switching losses on active devices. To overcome the wide input DC voltage variation problem for fuel cell energy and PV solar panel, the topology morphing between the half bridge circuit and full bridge circuit is adopted on the primary side to obtain low (or high) voltage gain under a high (or low) input voltage condition. Therefore, the stable DC voltage is controlled at the load side by using the variable switching frequency modulation. The studied hybrid CLLC converter is tested by a 1 kW prototype and the performance is verified and confirmed by experiments. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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20 pages, 30146 KiB

Open AccessArticle

Control Strategy Based on Arm-Level Control for Output and Circulating Current of MMC in Stationary Reference Frame

by Waqar Uddin, Tiago D. C. Busarello, Kamran Zeb, Muhammad Adil Khan, Anil Kumar Yedluri and Hee-Je Kim

Energies 2021, 14(14), 4160; https://doi.org/10.3390/en14144160 - 09 Jul 2021

Cited by 7 | Viewed by 2206

Abstract

This paper proposed a control method for output and circulating currents of modular multilevel converter (MMC). The output and circulating current are controlled with the help of arm currents, which contain DC, fundamental frequency, and double frequency components. The arm current is transformed [...] Read more.

This paper proposed a control method for output and circulating currents of modular multilevel converter (MMC). The output and circulating current are controlled with the help of arm currents, which contain DC, fundamental frequency, and double frequency components. The arm current is transformed into a stationary reference frame (SRF) to isolate the DC and AC components. The AC component is controlled with a conventional proportional resonant (PR) controller, while the DC component is controlled by a proportional controller. The effective control of the upper arm and lower arm ultimately controls the output current so that it delivers the required power to the grid and circulating current in such a way that the second harmonic component is completely vanished leaving behind only the DC component. Comparative results of leg-level control based on PR controller are included in the paper to show the effectiveness of the proposed control scheme. A three-phase, five-level MMC is developed in MATLAB/Simulink to verify the effectiveness of the proposed control method. Full article

(This article belongs to the Special Issue Design and Investigation of Power Electronics Converters and Its Control)

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