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Power Electronics 2018
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Power Electronics 2018

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

Deadline for manuscript submissions: closed (15 October 2018) | Viewed by 107817

Special Issue Editor

Prof. Dr. Kyo-Beum Lee

E-Mail Website
Guest Editor
Department of Electrical and Computer Engineering, Ajou University, World cup-row 206, Yeongtong-gu, Suwon 16499, Korea
Interests: power electronics; electric machine drives; wind and solar energy systems; electric vehicle applications
Special Issues, Collections and Topics in MDPI journals

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 submissions that pass pre-check are 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.

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 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 (21 papers)

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Research

23 pages, 5131 KiB  
Article
An Ant Colony Optimized MPPT for Standalone Hybrid PV-Wind Power System with Single Cuk Converter
by Neeraj Priyadarshi, Vigna K. Ramachandaramurthy, Sanjeevikumar Padmanaban and Farooque Azam
Energies 2019, 12(1), 167; https://doi.org/10.3390/en12010167 - 04 Jan 2019
Cited by 132 | Viewed by 6752
Abstract
This research work explains the practical realization of hybrid solar wind-based standalone power system with maximum power point tracker (MPPT) to produce electrical power in rural places (residential applications). The wind inspired Ant Colony Optimization (ACO)-based MPPT algorithm is employed for the purpose [...] Read more.
This research work explains the practical realization of hybrid solar wind-based standalone power system with maximum power point tracker (MPPT) to produce electrical power in rural places (residential applications). The wind inspired Ant Colony Optimization (ACO)-based MPPT algorithm is employed for the purpose of fast and accurate tracking power from wind energy system. Fuzzy Logic Control (FLC) inverter controlling strategy is adopted in this presented work compared to classical proportional-integral (PI) control. Moreover, single Cuk converter is operated as impedance power adapter to execute MPPT functioning. Here, ACO-based MPPT has been implemented with no voltage and current extra circuit requirement compared to existing evolutionary algorithms single cuk converter is employed to improve conversion efficiency of converter by maximizing power stages. DC-link voltage can be regulated by placing Cuk converter Permanent Magnet Synchronous Generator (PMSG) linked rectifier and inverter. The proposed MPPT method is responsible for rapid battery charging and gives power dispersion of battery for hybrid PV-Wind system. ACO-based MPPT provides seven times faster convergence compared to the particle swarm optimization (PSO) algorithm for achievement of maximum power point (MPP) and tracking efficiency. Satisfactory practical results have been realized using the dSPACE (DS1104) platform that justify the superiority of proposed algorithms designed under various operating situations. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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19 pages, 5861 KiB  
Article
Suppression of Switching Crosstalk and Voltage Oscillations in a SiC MOSFET Based Half-Bridge Converter
by Haider Zaman, Xiaohua Wu, Xiancheng Zheng, Shahbaz Khan and Husan Ali
Energies 2018, 11(11), 3111; https://doi.org/10.3390/en11113111 - 10 Nov 2018
Cited by 32 | Viewed by 13051
Abstract
The silicon carbide (SiC) MOSFET is characterized by high operating voltage, temperature, switching frequency and efficiency which enables a converter to achieve high power density. However, at high switching frequency, the crosstalk phenomenon occurs when the gate voltage spike introduced by high dv/dt [...] Read more.
The silicon carbide (SiC) MOSFET is characterized by high operating voltage, temperature, switching frequency and efficiency which enables a converter to achieve high power density. However, at high switching frequency, the crosstalk phenomenon occurs when the gate voltage spike introduced by high dv/dt and voltage ringing forces false turn-on of SiC MOSFET which causes a crow-bar current thereby increasing switching losses. In order to increase the immunity against the crosstalk phenomenon in a half-bridge configuration, this paper presents a gate driver for SiC MOSFET capable of generating the negative turn-off voltage without using a negative power supply. In addition, the effect of parasitic inductances on the switching response is analyzed and an RC snubber is designed using high-frequency based circuit reduction technique to dampen the switching ringing. The performance of the proposed gate driver and the designed RC snubber is validated using simulation and experiment at the 1 MHz switching frequency. The results show that the proposed gate driver with RC snubber eliminates crosstalk by maintaining any spurious gate spike below the gate threshold voltage. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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16 pages, 8504 KiB  
Article
DC-link Ripple Reduction in a DPWM-Based Two-Level VSI
by Anatolii Tcai, Ibrahim Mohd Alsofyani, In-Yong Seo and Kyo-Beum Lee
Energies 2018, 11(11), 3008; https://doi.org/10.3390/en11113008 - 01 Nov 2018
Cited by 6 | Viewed by 4169
Abstract
This paper proposes a new method to reduce the ripple current of the DC-link capacitor in a two-level voltage source inverter (VSI), with a discontinuous pulse-width modulation (DPWM). In real applications, a capacitor block is very bulky, due to the parallel connection of [...] Read more.
This paper proposes a new method to reduce the ripple current of the DC-link capacitor in a two-level voltage source inverter (VSI), with a discontinuous pulse-width modulation (DPWM). In real applications, a capacitor block is very bulky, due to the parallel connection of several capacitors that share the value of the ripple current. Hence, it contributes significantly to the volume and weight of the whole system. Conventional DPWM is used to minimize the amount of switching for the power transistors, therefore, reducing stress and power loss. This leads to increased efficiency and reliability of the system. Nevertheless, the reduction of the DC link ripple current is still not optimal. Therefore, the proposed method introduces a PWM phase-shift technique to provide further reduction of the DC-link ripple current in a DPWM-based VSI. The efficacy of the proposed method is confirmed by simulation and experimental results. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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18 pages, 4747 KiB  
Article
Fixed Frequency Sliding Mode Control of Power Converters for Improved Dynamic Response in DC Micro-Grids
by Abdul Rehman Yasin, Muhammad Ashraf and Aamer Iqbal Bhatti
Energies 2018, 11(10), 2799; https://doi.org/10.3390/en11102799 - 17 Oct 2018
Cited by 21 | Viewed by 3632
Abstract
The rapid decrease in conventional energy resources and their harmful impact on the environment has brought the attention of the researchers towards the use of renewable energy technologies. The renewable energy systems are connected to Direct Current (DC) micro-grids via power electronic converters [...] Read more.
The rapid decrease in conventional energy resources and their harmful impact on the environment has brought the attention of the researchers towards the use of renewable energy technologies. The renewable energy systems are connected to Direct Current (DC) micro-grids via power electronic converters where the load conditions are unknown and network parameters are uncertain. These conditions call for the use of robust control techniques such as Sliding Mode Control (SMC) in order to regulate the grid voltage. However, SMC has a drawback of operating the power converter at variable switching frequency which results in degrading the power quality. This paper introduces a fixed frequency sliding mode controller that does not suffer from this predicament. A novel double integral type switching manifold is proposed to achieve voltage regulation of a DC micro-grid, in the presence of unknown load demands and un-modeled dynamics of the network. Rigorous mathematical analysis is carried out for the stability of the closed loop system and the technique is experimentally validated on position of a DC micro-grid using a specially designed test rig. For benchmarking purposes, a conventional Proportional Integral (PI) controller is also implemented. An improvement of 2.5% in rise time, 6.7% in settling time and reduction of voltage dip by 31.7% during load transaction is achieved as compared to the PI controller. The experiment confirms the hypothesis that fixed frequency SMC shows better performance than its counterpart in the phase of introduced disturbances. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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18 pages, 2913 KiB  
Article
Intelligence-Based Battery Management and Economic Analysis of an Optimized Dual-Vanadium Redox Battery (VRB) for a Wind-PV Hybrid System
by Hina Fathima A, Kaliannan Palanisamy, Sanjeevikumar Padmanaban and Umashankar Subramaniam
Energies 2018, 11(10), 2785; https://doi.org/10.3390/en11102785 - 17 Oct 2018
Cited by 12 | Viewed by 3640
Abstract
This paper proposes an intelligent battery management system (BMS) implementing two large Vanadium Redox Battery (VRB) flow batteries in a master-slave mode to provide grid-level energy storage for a wind-solar hybrid power system. The proposed BMS is formulated to effectively meet a predetermined [...] Read more.
This paper proposes an intelligent battery management system (BMS) implementing two large Vanadium Redox Battery (VRB) flow batteries in a master-slave mode to provide grid-level energy storage for a wind-solar hybrid power system. The proposed BMS is formulated to effectively meet a predetermined power dispatch formulated based on forecasted wind and solar data while incorporating features like peak shaving and ramp rate limiting. It is compared to a single battery module operated system to showcase the advantages of the proposed intelligent dual battery module in terms of appreciable reduction in battery size and costs while exhibiting improved lifecycle performance. The battery size is optimized based on heuristic optimization algorithms and modelled in Matlab/Simulink environment. An intelligent fuzzy-based BMS is used to control the dual VRB model to ensure optimized power sharing between batteries. The simulations were carried out and an in-depth economic analysis conducted to analyze the costs and other financial metrics of the hybrid project. Results proved the advantages of the dual battery with the proposed BMS and fortify that the introduction of time-based tariffs and other incentives will further make investments in VRB highly attractive for renewable applications. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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15 pages, 1866 KiB  
Article
Robust Tracking Controller for a DC/DC Buck-Boost Converter–Inverter–DC Motor System
by Eduardo Hernández-Márquez, Carlos Alejandro Avila-Rea, José Rafael García-Sánchez, Ramón Silva-Ortigoza, Gilberto Silva-Ortigoza, Hind Taud and Mariana Marcelino-Aranda
Energies 2018, 11(10), 2500; https://doi.org/10.3390/en11102500 - 20 Sep 2018
Cited by 22 | Viewed by 3802
Abstract
This paper has two aims. The first is to develop a robust hierarchical tracking controller for the DC/DC Buck-Boost–inverter–DC motor system. This controller considers a high level control for the inverter–DC motor subsystems and a low level control for the DC/DC Buck-Boost converter [...] Read more.
This paper has two aims. The first is to develop a robust hierarchical tracking controller for the DC/DC Buck-Boost–inverter–DC motor system. This controller considers a high level control for the inverter–DC motor subsystems and a low level control for the DC/DC Buck-Boost converter subsystem. Such controls solve the tracking task associated with the angular velocity of the motor shaft and the output voltage of the converter, respectively, via the differential flatness approach. The second aim is to present a comparison of the robust hierarchical controller to a passive controller. This, with the purpose of showing that performance achieved with the hierarchical controller proposed in this paper, is better than the one achieved with the passive controller. Both controllers are experimentally implemented on a prototype of the DC/DC Buck-Boost–inverter–DC motor system by using Matlab-Simulink along with the DS1104 board from dSPACE. According to experimental results, the proposal in the present paper achieves a better performance than the passive controller. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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14 pages, 3182 KiB  
Article
A Simplified Minimum DC-Link Voltage Control Strategy for Shunt Active Power Filters
by Yu Wang, Yuewu Wang, Si-Zhe Chen, Guidong Zhang and Yun Zhang
Energies 2018, 11(9), 2407; https://doi.org/10.3390/en11092407 - 12 Sep 2018
Cited by 13 | Viewed by 5142
Abstract
The active power filter (APF) is a popular electrical device to eliminate harmonics in power systems. The rational design and effective control of DC-link capacitor voltage are important for implementing APF functions. In this study, the influences from the DC-link voltage on the [...] Read more.
The active power filter (APF) is a popular electrical device to eliminate harmonics in power systems. The rational design and effective control of DC-link capacitor voltage are important for implementing APF functions. In this study, the influences from the DC-link voltage on the APF compensating current characteristic and compensation performance are analyzed, and the reason to maintain DC-link voltage at a minimum value is investigated. On this basis, a simplified minimum DC-link voltage control strategy for APF is proposed. Compared with the existing DC-link voltage control strategies, the minimum DC-link voltage value in proposed strategy is only determined by the grid voltage and modulation ratio, reducing the calculation burden and the implementation difficulty in application, avoiding the interference from external parameters on the compensation effect. Additionally, the reference DC-link voltage varies at different values according to the grid voltage and modulation ratio. A shunt APF prototype is established and the experimental results verify the correctness and effectiveness of the analysis and proposed strategy. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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13 pages, 4879 KiB  
Article
DC Offset Error Compensation Algorithm for PR Current Control of a Single-Phase Grid-Tied Inverter
by Jae Suk Lee and Seon-Hwan Hwang
Energies 2018, 11(9), 2308; https://doi.org/10.3390/en11092308 - 02 Sep 2018
Cited by 8 | Viewed by 5962
Abstract
In a single-phase grid-tied inverter, the direct current (DC) offset error included in the measured grid side phase current has various causes, such as a non-ideal current sensor, unbalanced power supply of an operational amplifier, and nonlinear features of analog components in interface [...] Read more.
In a single-phase grid-tied inverter, the direct current (DC) offset error included in the measured grid side phase current has various causes, such as a non-ideal current sensor, unbalanced power supply of an operational amplifier, and nonlinear features of analog components in interface circuits, etc. If the DC offset error is included in the measured current, it causes the secondary harmonic of fundamental frequency and the DC component in grid phase current which result in degradation of inverter performance. In this paper, a theoretical detection method of the secondary harmonic of the fundamental frequency and a DC component in grid phase current for a proportional-resonant (PR) current control system is introduced. Based on the detection method, an algorithm for compensating DC offset error is also presented for single-phase grid-tied inverters. Simulation results and experimental verification of the DC offset error compensation algorithm are shown in this paper. Full article
(This article belongs to the Special Issue Power Electronics 2018)
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15 pages, 2936 KiB  
Article
DC/DC Boost Converter–Inverter as Driver for a DC Motor: Modeling and Experimental Verification
by Víctor Hugo García-Rodríguez, Ramón Silva-Ortigoza, Eduardo Hernández-Márquez, José Rafael García-Sánchez and Hind Taud
Energies 2018, 11(8), 2044; https://doi.org/10.3390/en11082044 - 07 Aug 2018
Cited by 22 | Viewed by 5758
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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14 pages, 4420 KiB  
Article
Temperature Estimation of Stator Winding in Permanent Magnet Synchronous Motors Using d-Axis Current Injection
by Bum-Su Jun, Joon Sung Park, Jun-Hyuk Choi, Ki-Doek Lee and Chung-Yuen Won
Energies 2018, 11(8), 2033; https://doi.org/10.3390/en11082033 - 06 Aug 2018
Cited by 17 | Viewed by 4893
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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19 pages, 17994 KiB  
Article
Analysis, Design and Implementation of Droop-Controlled Parallel-Inverters Using Dynamic Phasor Model and SOGI-FLL in Microgrid Applications
by Bum-Jun Kim, Ho-Jung Kum, Jung-Min Park and Chung-Yuen Won
Energies 2018, 11(7), 1683; https://doi.org/10.3390/en11071683 - 27 Jun 2018
Cited by 4 | Viewed by 4749
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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14 pages, 2013 KiB  
Article
SOC Estimation of Multiple Lithium-Ion Battery Cells in a Module Using a Nonlinear State Observer and Online Parameter Estimation
by Ngoc-Tham Tran, Abdul Basit Khan, Thanh-Tung Nguyen, Dae-Wook Kim and Woojin Choi
Energies 2018, 11(7), 1620; https://doi.org/10.3390/en11071620 - 21 Jun 2018
Cited by 13 | Viewed by 3575
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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14 pages, 3853 KiB  
Article
A Four-Level T-Type Neutral Point Piloted Inverter for Solar Energy Applications
by Saddam Shueai Alnamer, Saad Mekhilef and Hazlie Bin Mokhlis
Energies 2018, 11(6), 1546; https://doi.org/10.3390/en11061546 - 13 Jun 2018
Cited by 5 | Viewed by 4246
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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16 pages, 7666 KiB  
Article
Improvement of Transient State Response through Feedforward Compensation Method of AC/DC Power Conversion System (PCS) Based on Space Vector Pulse Width Modulation (SVPWM)
by Seok-Jin Hong, Seung-Wook Hyun, Kyung-Min Kang, Jung-Hyo Lee and Chung-Yuen Won
Energies 2018, 11(6), 1468; https://doi.org/10.3390/en11061468 - 06 Jun 2018
Cited by 5 | Viewed by 3853
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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18 pages, 5915 KiB  
Article
Design and Control of Small DC-Link Capacitor-Based Three-Level Inverter with Neutral-Point Voltage Balancing
by Hyo-Chul In, Seok-Min Kim and Kyo-Beum Lee
Energies 2018, 11(6), 1435; https://doi.org/10.3390/en11061435 - 04 Jun 2018
Cited by 15 | Viewed by 4909
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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18 pages, 7141 KiB  
Article
An Integrated Current-Voltage Compensator Design Method for Stable Constant Voltage and Current Source Operation of LLC Resonant Converters
by Yeong-Jun Choi, Hwa-Rang Cha, Sang-Min Jung and Rae-Young Kim
Energies 2018, 11(6), 1325; https://doi.org/10.3390/en11061325 - 23 May 2018
Cited by 4 | Viewed by 3766
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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22 pages, 13406 KiB  
Article
Improving Line Current Distortion in Single-Phase Vienna Rectifiers Using Model-Based Predictive Control
by Yong-Dae Kwon, Jin-Hyuk Park and Kyo-Beum Lee
Energies 2018, 11(5), 1237; https://doi.org/10.3390/en11051237 - 12 May 2018
Cited by 18 | Viewed by 6407
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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17 pages, 2357 KiB  
Article
A Robust Current Controller for Uncertain Permanent Magnet Synchronous Motors with a Performance Recovery Property for Electric Power Steering Applications
by Yonghun Kim, Hyung-Tae Seo, Seok-Kyoon Kim and Kyung-Soo Kim
Energies 2018, 11(5), 1224; https://doi.org/10.3390/en11051224 - 10 May 2018
Cited by 11 | Viewed by 5216
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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17 pages, 1872 KiB  
Article
Implementation of a Smart Power Conditioning System for Energy Storage System with a Novel Seamless Transfer Strategy
by Ki-Ryong Kim, Chang-Yeol Oh, Tae-Jin Kim, Jong-Pil Lee and Hee-Je Kim
Energies 2018, 11(5), 1108; https://doi.org/10.3390/en11051108 - 01 May 2018
Cited by 4 | Viewed by 2866
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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25 pages, 8782 KiB  
Article
An Enhanced Control Scheme Based on New Adaptive Filters for Cascaded NPC/H-Bridge System
by Jin-Wook Kang, Hoon Lee, Seung-Wook Hyun, Jintae Kim and Chung-Yuen Won
Energies 2018, 11(5), 1034; https://doi.org/10.3390/en11051034 - 24 Apr 2018
Cited by 4 | Viewed by 4146
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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16 pages, 8828 KiB  
Article
A DAB Converter with Common-Point-Connected Winding Transformers Suitable for a Single-Phase 5-Level SST System
by Hyeok-Jin Yun, Ho-Sung Kim, Myoungho Kim, Ju-Won Baek and Hee-Je Kim
Energies 2018, 11(4), 928; https://doi.org/10.3390/en11040928 - 13 Apr 2018
Cited by 4 | Viewed by 5692
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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