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Special Issue "Power Electronics 2018"

A special issue of Energies (ISSN 1996-1073).

Deadline for manuscript submissions: 15 October 2018

Special Issue Editor

Guest Editor
Prof. Dr. Kyo-Beum Lee

Department of Electrical and Computer Engineering, Ajou University, Worldcupro 206, Yeongtong-gu, Suwon 16499, Korea
Website | E-Mail
Phone: +82 31 219 2376
Interests: power electronics; electric machine drives; wind and solar energy systems; electric vehicle applications

Special Issue Information

Dear Colleagues,

Recent advances in power electronics have enabled the rapid development of applications in power systems, including renewable energy generation, high-voltage DC (HVDC) transmission, flexible AC transmission system, energy storage, electric vehicles, and microgrids. Power electronics are also the foundation for new mobile power system technologies, such as variable-frequency AC distribution for more-electric aircraft and medium-voltage DC grids for electric ships. This Special Issue focuses on the analysis, design, and implementation of power electronics systems.

Prof. Dr. Kyo-Beum Lee
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Energies is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Control of power electronics systems
  • Topology of power electronics systems
  • Adjustable speed drives
  • Power quality and utility applications
  • Reliability of power converters
  • Electric vehicle applications
  • Renewable energy applications

Published Papers (13 papers)

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Research

Open AccessArticle DC/DC Boost Converter–Inverter as Driver for a DC Motor: Modeling and Experimental Verification
Energies 2018, 11(8), 2044; https://doi.org/10.3390/en11082044
Received: 29 June 2018 / Revised: 21 July 2018 / Accepted: 27 July 2018 / Published: 7 August 2018
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Abstract
In this paper, the modeling and the experimental verification of the “bidirectional DC/DC boost converter–DC motor” system are presented. By using circuit theory along with the model of a DC motor, the mathematical model of the system is derived. This model was experimentally
[...] Read more.
In this paper, the modeling and the experimental verification of the “bidirectional DC/DC boost converter–DC motor” system are presented. By using circuit theory along with the model of a DC motor, the mathematical model of the system is derived. This model was experimentally tested under time-varying duty cycles obtained via the system differential flatness property. The experimental verification was carried out using Matlab-Simulink and a DS1104 board in a built prototype of the system. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle Temperature Estimation of Stator Winding in Permanent Magnet Synchronous Motors Using d-Axis Current Injection
Energies 2018, 11(8), 2033; https://doi.org/10.3390/en11082033
Received: 9 July 2018 / Revised: 30 July 2018 / Accepted: 30 July 2018 / Published: 6 August 2018
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Abstract
This paper presents a stator winding temperature detection method for permanent magnet synchronous motors (PMSMs) using a motor parameter estimation method. PMSM performance is highly dependent on the motor parameters. However, the motor parameters vary with temperature. It is difficult to measure motor
[...] Read more.
This paper presents a stator winding temperature detection method for permanent magnet synchronous motors (PMSMs) using a motor parameter estimation method. PMSM performance is highly dependent on the motor parameters. However, the motor parameters vary with temperature. It is difficult to measure motor parameters using a voltage equation without additional sensors. Herein, a stator winding temperature estimation method based on a d-axis current injection method is proposed. The proposed estimation method can be used to obtain stator temperatures and to achieve reliable operation. The validity of the proposed method is verified through simulations and experimental results. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle Analysis, Design and Implementation of Droop-Controlled Parallel-Inverters Using Dynamic Phasor Model and SOGI-FLL in Microgrid Applications
Energies 2018, 11(7), 1683; https://doi.org/10.3390/en11071683
Received: 7 June 2018 / Revised: 22 June 2018 / Accepted: 26 June 2018 / Published: 27 June 2018
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Abstract
The droop control strategy is widely used in islanded microgrids to control power flows according to the load condition, with the absence of a critical communication line, interfacing distributed energy sources to provide for the active and reactive power demand of loads. In
[...] Read more.
The droop control strategy is widely used in islanded microgrids to control power flows according to the load condition, with the absence of a critical communication line, interfacing distributed energy sources to provide for the active and reactive power demand of loads. In this case, the system modeling for both steady-state and transient time is one of the key issues of a droop-controlled system for an inverter-based microgrid (MG). With the rapid development of microgrids, it is essential to identify the system stability and optimize the control parameters, taking into account the network and control dynamics caused by multiple tasks such as electric signal filtering, network synchronization, and so on. Therefore, in order to improve model accuracy and determine control coefficients, this paper analyzes and extends a dynamic phasor-based model to the droop-controlled parallel-inverters, considering network and control dynamics such as a low-pass filter, a second-order generalized integrator frequency-locked-loop (SOGI-FLL), and a system operating sequence. Moreover, discussed in this paper are both the design approaches for and the implementation of a droop-controlled parallel-inverter, which enables the system to be stable and reliable. To demonstrate the effectiveness and validity of this paper, PSIM simulation was performed and two parallel-inverters were combined as the proposed design procedure for the 4-kVA prototypes. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle SOC Estimation of Multiple Lithium-Ion Battery Cells in a Module Using a Nonlinear State Observer and Online Parameter Estimation
Energies 2018, 11(7), 1620; https://doi.org/10.3390/en11071620
Received: 2 June 2018 / Revised: 17 June 2018 / Accepted: 18 June 2018 / Published: 21 June 2018
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Abstract
In recent years, electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in electric vehicles (PEVs) have become very popular. Therefore, the use of secondary batteries exponentially increased in EV systems. Battery fuel gauges determine the amount of charge inside the battery, and how
[...] Read more.
In recent years, electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in electric vehicles (PEVs) have become very popular. Therefore, the use of secondary batteries exponentially increased in EV systems. Battery fuel gauges determine the amount of charge inside the battery, and how much farther the vehicle can drive itself under specific operating conditions. It is very important to provide accurate state-of-charge (SOC) information of the battery module to the driver, since inaccurate fuel gauges will not be tolerated. In this paper, a model-based approach is proposed to estimate the SOCs of multiple lithium-ion (Li-ion) battery cells, connected in a module in series, by using a nonlinear state observer (NSO) and an online parameter identification algorithm. A simple method of estimating the impedance and SOC of each cell in a module is also presented in this paper, by employing a ratio vector with respect to the reference value. A battery model based on an autoregressive model with exogenous input (ARX) was used with recursive least squares (RLS) for parameter identification, in an effort to guarantee reliable estimation results under various operating conditions. The validity and feasibility of the proposed algorithm were verified by an experimental setup of six Li-ion battery cells connected in a module in series. It was found that, when compared with a simple linear state observer (LSO), an NSO can further reduce the SOC error by 1%. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle A Four-Level T-Type Neutral Point Piloted Inverter for Solar Energy Applications
Energies 2018, 11(6), 1546; https://doi.org/10.3390/en11061546
Received: 9 April 2018 / Revised: 25 May 2018 / Accepted: 28 May 2018 / Published: 13 June 2018
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Abstract
Multilevel inverters provide an output signal with low harmonic distortion and superior output voltages. This work proposes a new four-level T-type neutral point piloted (T-NPP) topology with higher efficiency and low total harmonic distortion (THD) and with the ability to withstand high voltage
[...] Read more.
Multilevel inverters provide an output signal with low harmonic distortion and superior output voltages. This work proposes a new four-level T-type neutral point piloted (T-NPP) topology with higher efficiency and low total harmonic distortion (THD) and with the ability to withstand high voltage stresses, especially for high-power applications. The proposed topology is designed in such manner that the direct current (DC)-voltage stresses split over the components with strong possibilities to increase the load current and switching frequency. However, the operation of the proposed topology is based on two essential principles. The first principle is that each upper and lower switch of each leg consists of two insulated gate bipolar transistors (IGBTs) connected in series in order to withstand high voltage stresses and make it split over the two IGBTs in each switch. The second principle is using the DC-link circuit (T1 & T2) to generate 2Vdc and 1Vdc by connecting the bidirectional switches of each leg to the DC-link’s mid-point. Furthermore, the proposed four-level T-NPP inverter outperforms other converters by the high number of output voltage level, low number of components, simple structure and higher efficiency. Finally, the proposed T-NPP topology concept was validated via simulation, experiments and theoretical analysis. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle Improvement of Transient State Response through Feedforward Compensation Method of AC/DC Power Conversion System (PCS) Based on Space Vector Pulse Width Modulation (SVPWM)
Energies 2018, 11(6), 1468; https://doi.org/10.3390/en11061468
Received: 30 April 2018 / Revised: 1 June 2018 / Accepted: 3 June 2018 / Published: 6 June 2018
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Abstract
In a DC distribution system configured by AC/DC power conversion system (PCS), the voltage control performance of the AC/DC PCS determines the stability and reliability of the DC distribution grid. The DC voltage of grid is maintained by capacitor, thus transient voltage is
[...] Read more.
In a DC distribution system configured by AC/DC power conversion system (PCS), the voltage control performance of the AC/DC PCS determines the stability and reliability of the DC distribution grid. The DC voltage of grid is maintained by capacitor, thus transient voltage is an inevitable problem when a grid is connected with a high amount of load or renewable energy. Space vector pulse width modulation (SVPWM) is well known as a stable modulation method and is used in AC/DC PCS and many types of topologies, but a solution for the transient states issue of DC link has not clearly been studied. In this paper, a feedforward compensation method based on the mathematical model of SVPWM is proposed to solve the transient state problem in a DC distribution system. The proposed method is verified by simulation and experiment. AC/DC PCS with the proposed feedforward compensation method has more robust DC voltage control characteristics. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle Design and Control of Small DC-Link Capacitor-Based Three-Level Inverter with Neutral-Point Voltage Balancing
Energies 2018, 11(6), 1435; https://doi.org/10.3390/en11061435
Received: 19 April 2018 / Revised: 23 May 2018 / Accepted: 30 May 2018 / Published: 4 June 2018
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Abstract
This paper presents a method to improve the quality of input-output currents in a three-level neutral-point clamped (NPC) inverter with small direct current-link (DC-link) capacitor systems. The inverter systems with the small DC-link capacitors have several advantages in terms of cost, volume, life-time,
[...] Read more.
This paper presents a method to improve the quality of input-output currents in a three-level neutral-point clamped (NPC) inverter with small direct current-link (DC-link) capacitor systems. The inverter systems with the small DC-link capacitors have several advantages in terms of cost, volume, life-time, and reliability when compared to inverters that use large DC-link capacitors. However, there are problems with respect to the deterioration of the input current quality and a severe ripple of neutral-point voltage (NPV), which can cause an aggravated output current. To mitigate these issues, an additional circuit is applied for the input current shaping and a compensation algorithm is applied to reduce the ripple voltage of NPV. The effectiveness of the proposed design and control method is verified with various simulation and experimental results. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle An Integrated Current-Voltage Compensator Design Method for Stable Constant Voltage and Current Source Operation of LLC Resonant Converters
Energies 2018, 11(6), 1325; https://doi.org/10.3390/en11061325
Received: 27 April 2018 / Revised: 18 May 2018 / Accepted: 21 May 2018 / Published: 23 May 2018
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Abstract
This paper proposes a method to charge a lithium ion battery with an integrated compensator. Unlike the conventional charging method which uses separate voltage/current compensators based on a constant voltage-constant current charge profile, the proposed method uses a single compensator. The conventional method
[...] Read more.
This paper proposes a method to charge a lithium ion battery with an integrated compensator. Unlike the conventional charging method which uses separate voltage/current compensators based on a constant voltage-constant current charge profile, the proposed method uses a single compensator. The conventional method requires a complicated design process such as separate plant modeling for compensator design and the compensator tuning process in the frequency domain. Moreover, it has the disadvantage of a transient state between the mode change. However, the proposed method simplifies the complicated process and eliminates the transient response. The proposed compensator is applied to the LLC resonant converter and is designed to provide smooth and reliable performance during the entire charging process. In this paper, for the compensator design, the frequency domain models of the LLC resonant converter at the constant voltage and constant current charging mode are derived including the impedance model of the battery pack. Additionally, the worst condition of the compensator design during the entire charging process is considered. To demonstrate the effectiveness of the proposed method, the theoretical design procedure is presented in this paper, and it is verified through experimental results using a 300 W LLC converter and battery pack. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessFeature PaperArticle Improving Line Current Distortion in Single-Phase Vienna Rectifiers Using Model-Based Predictive Control
Energies 2018, 11(5), 1237; https://doi.org/10.3390/en11051237
Received: 21 April 2018 / Revised: 10 May 2018 / Accepted: 10 May 2018 / Published: 12 May 2018
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Abstract
Conventional single-phase Vienna rectifiers employ proportional-integral (PI) controllers which are appropriate for controlling DC components, to regulate their line currents. However, in the regions close to the line current’s zero-crossing point, the dynamics of PI controllers are too slow to respond to the
[...] Read more.
Conventional single-phase Vienna rectifiers employ proportional-integral (PI) controllers which are appropriate for controlling DC components, to regulate their line currents. However, in the regions close to the line current’s zero-crossing point, the dynamics of PI controllers are too slow to respond to the reference current, which has an AC component. Hence, the power factor (PF) of the device is degenerated, and total harmonic distortion (THD) increases. A controller with a fast dynamic response is thus required to solve this problem. In this paper, we investigate the use of a model-based predictive controller (MPC), which has a faster dynamic response than a PI controller, to improve the line current quality of a single-phase Vienna rectifier. With this method, the average current in both the continuous current mode (CCM) and the discontinuous current mode (DCM) of operation are controlled using a mode detection method. Moreover, we calculate the optimized duty cycle for the single-phase Vienna rectifier, by predicting the next current state. We verify the operation of the proposed algorithm using a PSIM simulation, and a practical experiment conducted with a 1-kW-rated single-phase Vienna rectifier prototype. With the proposed method, the quality of the line current near the zero-crossing point is improved, and the PF is controlled to unity. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle A Robust Current Controller for Uncertain Permanent Magnet Synchronous Motors with a Performance Recovery Property for Electric Power Steering Applications
Energies 2018, 11(5), 1224; https://doi.org/10.3390/en11051224
Received: 23 March 2018 / Revised: 3 May 2018 / Accepted: 7 May 2018 / Published: 10 May 2018
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Abstract
This paper presents a robust current tracking controller for permanent magnet synchronous motors (PMSMs) with a performance recovery property for electric power steering (EPS) applications. The contributions of this work are twofold. First, a disturbance observer (DOB) is designed to compensate the disturbances
[...] Read more.
This paper presents a robust current tracking controller for permanent magnet synchronous motors (PMSMs) with a performance recovery property for electric power steering (EPS) applications. The contributions of this work are twofold. First, a disturbance observer (DOB) is designed to compensate the disturbances arising from the model–plant mismatches while reducing the closed-loop sensitivity. Second, a current controller is designed to improve the current tracking performance in the frequency domain by assigning the performance recovery property to the closed-loop system. The closed-loop performance is verified through simulations and experiments using a 500 W PMSM connected to an EPS system. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle Implementation of a Smart Power Conditioning System for Energy Storage System with a Novel Seamless Transfer Strategy
Energies 2018, 11(5), 1108; https://doi.org/10.3390/en11051108
Received: 23 March 2018 / Revised: 18 April 2018 / Accepted: 26 April 2018 / Published: 1 May 2018
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Abstract
Implementation of a smart power conditioning system with a novel seamless transfer method for an energy storage system (ESS) was proposed in this paper. The power conditioning system is to control the power quality or protect the grid system. Therefore, it requires various
[...] Read more.
Implementation of a smart power conditioning system with a novel seamless transfer method for an energy storage system (ESS) was proposed in this paper. The power conditioning system is to control the power quality or protect the grid system. Therefore, it requires various functions. One of the these functions, the uninterruptible power supply (UPS) function, was applied to proposed power conditioning system. In order for the grid-interactive power conditioning system to continuously supply power to the load, two operation modes are required depending on the grid state. One is the grid connected (GC) mode and the other is the stand-alone (SA) mode. Under normal grid condition, the power conditioning system is operated in GC mode and controls the current. On the other hand, under abnormal grid conditions such as grid outage, the power conditioning system operates in SA mode and supplies power to the load. Unintentional sudden changes in operating mode cause unwanted phenomena (e.g., voltage/current spike, inrush current) which can make system degradation or failure. To improve this situation, the seamless transfer function became necessary. In this paper, by adding seamless function to power conditioning system, it is possible to supply power to the load stably regardless of grid state. In addition, it is possible to prevent secondary accident and to operate stably even if non-detection zone condition occurs by using an active frequency method. The proposed control algorithm was verified through field experiments. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessArticle An Enhanced Control Scheme Based on New Adaptive Filters for Cascaded NPC/H-Bridge System
Energies 2018, 11(5), 1034; https://doi.org/10.3390/en11051034
Received: 31 March 2018 / Revised: 18 April 2018 / Accepted: 20 April 2018 / Published: 24 April 2018
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Abstract
This paper studies the voltage fluctuation of dc-link generated in a 13-level cascaded neutral point clamped (NPC)/h-bridge (CNHB) with single-phase active front end (AFE) at the input side of each cell. The voltage fluctuation may deteriorate the power factor (PF) and current harmonics
[...] Read more.
This paper studies the voltage fluctuation of dc-link generated in a 13-level cascaded neutral point clamped (NPC)/h-bridge (CNHB) with single-phase active front end (AFE) at the input side of each cell. The voltage fluctuation may deteriorate the power factor (PF) and current harmonics in the system. In this paper, new adaptive filters are proposed to overcome the problem. The center frequency of the proposed filters can be automatically varied, which allows to eliminate the specific harmonics in the dc-link well rather than the conventional one. Therefore, it can reduce the fluctuation of dc-link and maintain high PF and low current harmonic distortion without additional circuits externally or the current harmonics injection technique. As a result, capacitance for the dc-link can be optimally designed, and even cost and volume of the system can be reduced. This paper analyzes reasons of increasing voltage fluctuation theoretically and the conventional filter and proposed two types of adaptive filters are compared. In addition, the optimal design method of the dc-link capacitor necessarily used in NPC/h-bridge is presented. To verify the principle and feasibility of the proposed control method, a simulation and experiment are implemented with the CNHB system. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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Open AccessFeature PaperArticle A DAB Converter with Common-Point-Connected Winding Transformers Suitable for a Single-Phase 5-Level SST System
Energies 2018, 11(4), 928; https://doi.org/10.3390/en11040928
Received: 21 March 2018 / Revised: 10 April 2018 / Accepted: 11 April 2018 / Published: 13 April 2018
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Abstract
One of the main disadvantages of the multi-level solid-state transformer (SST) system is the voltage imbalance on the output of the rectifier modules. This voltage imbalance can be caused by parameter mismatch of the active and passive components, different loads, and the floating
[...] Read more.
One of the main disadvantages of the multi-level solid-state transformer (SST) system is the voltage imbalance on the output of the rectifier modules. This voltage imbalance can be caused by parameter mismatch of the active and passive components, different loads, and the floating structure of the high voltage DC-links. Some studies have been done to solve this voltage imbalance problem. A common way to avoid this imbalance is to balance the voltage of DC-links at the AC/DC conversion stage and balance the power between the modules at the DC/DC conversion stage. Most of these methods require a complex balancing controller or additional circuits. This paper proposes a novel dual active bridge (DAB) converter specialized in power balancing in a single-phase 5-level SST system. The proposed DAB converter does not require any additional balancing controllers or techniques for power balancing. The performance of the proposed DAB converter was verified by simulation and experiments using a 3 kW 5-level SST prototype system. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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