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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Transactions of the Korean Institute of Power Electronics
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Journal DOI :
The Korean Institute of Power Electronics
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Volume & Issues
Volume 21, Issue 4 - Aug 2016
Volume 21, Issue 3 - Jun 2016
Volume 21, Issue 2 - Apr 2016
Volume 21, Issue 1 - Feb 2016
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Three-Level Zeta Converter using a Coupled Inductor
Lee, Seung-Jae ; Yang, Min-Kwon ; Heo, Jun ; Choi, Woo-Young ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 191~199
DOI : 10.6113/TKPE.2016.21.3.191
Conventional two-level Zeta converters have drawbacks, such as high voltage stresses and high current ripples. To address these problems, a three-level Zeta converter that uses a couple inductor is proposed in this study. The proposed converter utilizes the three-level power switching circuit to reduce the voltage stresses and inductor current ripples. Compared with the conventional converter, the proposed converter can improve power efficiency and power density. A 500 W prototype circuit is used to verify the operation and performance of the proposed converter via experimental results.
Parallel Operation Control Method of Grid-connected Inverters with Seamless Transfer for Energy Storage System in Microgrid
Park, Sung-Youl ; Kim, Joo-Ha ; Jung, Ah-Jin ; Choi, Se-Wan ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 200~206
DOI : 10.6113/TKPE.2016.21.3.200
In the microgrid, inverters for energy storage system are generally constructed in a parallel structure because of capacity expandability, convenience of system maintenance, and reliability improvement. Parallel inverters are required to provide stable voltage to the critical load in PCC and to accurately share the current between each inverter. Furthermore, when islanding occurs, the inverters should change its operating mode from grid-connected mode to stand-alone mode. However, during clearing time and control mode change, the conventional control method has a negative impact on the critical load, that is, severe fluctuating voltage. In this study, a parallel operation control method is proposed. This method provides seamless mode transfer for the entire transition period, including clearing time and control mode change, and has accurate current sharing between each inverter. The proposed control method is validated through simulation and experiment.
An Effective Gyrator-based Transformer Modeling using PSIM
Choi, Hee-Su ; Choi, Sung-Jin ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 207~214
DOI : 10.6113/TKPE.2016.21.3.207
Magnetic circuit is a physical modeling method that is useful in designing and analyzing power transformers, especially for a priori evaluation of leakage and magnetizing inductance before actual production. In this study, a novel modeling approach that uses PSIM magnetic elements adopting gyrator and permeance-capacitances is investigated. A formula to determine the permeance-capacitors in the core and leakage path are established, and a simulation jig is devised to link the physical model and the electrical terminal characteristics with an automated parameter determination process. The derived formula is verified by measurement results of the prototype transformer samples. Given its accuracy and simplicity, this approach is suitable for analyzing and designing LLC resonant transformers whose leakage and magnetizing inductance are very critical to circuit operation.
A Novel Rotor Position Estimation Method using a Rotation Matrix for a Square-Wave Signal Injected Sensorless Control in IPMSM
Kim, Sang-Il ; Kim, Rae-Young ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 215~223
DOI : 10.6113/TKPE.2016.21.3.215
In this study, a novel rotor position sensorless estimation method of an interior permanent-magnet synchronous motor is proposed. A square-wave pulsating voltage signal is injected in the estimated synchronous reference frame. This signal is interpreted in the stationary reference frame regardless of the estimated rotor position. Thus, assuming that the position error is nearly zero is unnecessary because the variables in the estimated synchronous reference frame are not used. The rotor position can be exactly calculated from two voltage references and three sampled current feedbacks in the stationary reference frame. The proposed method is easy to implement and helps enhance the bandwidth of the current controller. The validity of the proposed method is verified by simulations and experiments.
Single-Power-Conversion Series-Resonant AC-DC Converter with High Efficiency
Jeong, Seo-Gwang ; Cha, Woo-Jun ; Lee, Sung-Ho ; Kwon, Bong-Hwan ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 224~230
DOI : 10.6113/TKPE.2016.21.3.224
In this study, a single-power-conversion series-resonant ac-dc converter with high efficiency and high power factor is proposed. The proposed ac-dc converter consists of single-ended primary-inductor converter with an active-clamp circuit and a voltage doubler with series-resonant circuit. The active-clamp circuit clamps the surge voltage and provides zero-voltage switching of the main switch. The series-resonant circuit consists of leakage inductance
of the transformer and resonant capacitors
. This circuit also provides zero-current switching of output diodes
. Thus, the switching loss of switches and reverse-recovery loss of output diodes are considerably reduced. The proposed ac-dc converter also achieves high power factor using the proposed control algorithm without the addition of a power factor correction circuit and a dc-link electrolytic capacitor. A detailed theoretical analysis and the experimental results for a 1kW prototype are discussed.
DC-Voltage Regulation for Solar-Variable Speed Hybrid System
Niyitegeka, Gedeon ; Lee, Kyungkyu ; Choi, Jaeho ; Song, Yujin ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 231~237
DOI : 10.6113/TKPE.2016.21.3.231
Recently, the interest in DC systems to achieve more efficient connection with renewable energy sources, energy storage systems, and DC loads has been growing extensively. DC systems are more advantageous than AC systems because of their low conversion losses. However, the DC-link voltage is variable during operation because of different random effects. This study focuses on DC voltage stabilization applied in stand-alone DC microgrids by means of voltage ranges, power management, and coordination scheme. The quality and stability of the entire system are improved by keeping the voltage within acceptable limits. In terms of optimized control, the maximum power should be tracked from renewable resources during different operating modes of the system. The ESS and VSDG cover the power shortage after all available renewable energy is consumed. Keeping the state of charge of the ESS within the allowed bands is the key role of the control system. Load shedding or power generation curtailment should automatically occur if the maximum tolerable voltage variation is exceeded. PSIM-based simulation results are presented to evaluate the performance of the proposed control measures.
Automatic Command Mode Transition Strategy of Direct Power Control for PMSG MV Offshore Wind Turbines
Kwon, Gookmin ; Suh, Yongsug ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 238~248
DOI : 10.6113/TKPE.2016.21.3.238
In this study, an automatic command mode transition strategy of direct power control (DPC) is proposed for permanent magnet synchronous generators (PMSGs) medium-voltage (MV) offshore wind turbines (WTs). Benchmarking against the control methods are performed based on a three-level neutral-point-clamped (NPC) back-to-back type voltage source converter (VSC). The ramping rate criterion of complex power is utilized to select the switching vector in DPC for a three-level NPC converter. With a grid command and an MPPT mode transition strategy, the proposed control method automatically controls the generated output power to satisfy a grid requirement from the hierarchical wind farm controller. The automatic command mode transition strategy of DPC is confirmed through PLECS simulations based on Matlab. The simulation result of the automatic mode transition strategy shows that the proposed control method of VOC and DPC achieves a much shorter transient time of generated output power than the conventional control methods of MPPT and VOC under a step response. The proposed control method helps provide a good dynamic performance for PMSGs MV offshore WTs, thereby generating high quality output power.
Study on Speed Ripple Reduction Algorithm in Sensorless Controlled IPMSM
Lee, Song-Cheol ; Jung, Young-Seok ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 249~253
DOI : 10.6113/TKPE.2016.21.3.249
In this study, a harmonic-pulsation-compensator (HPC) is presented to reduce a periodic speed ripple in IPMSM. A proportional-integral compensator in HPC is proposed instead of the existing integral compensator to reduce the speed ripple more rapidly. A formula to calculate a rotation angle is also proposed, making compensation optimal in sensored and sensorless controls. The validity of the proposed algorithm is verified by experiments.
Analysis on Electric Shock Current in DC Electricity
Lee, Jin-Sung ; Kim, Hyosung ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 254~259
DOI : 10.6113/TKPE.2016.21.3.254
Recently, DC distribution systems have become a hot issue because of the increase in digital loads and DC generation systems according to the expansion of renewable energy technologies. To obtain the practical usage of DC electricity, safety should be guaranteed. The main concerns for safety are twofold: one side is human protection against electric shocks, and the other is facility protection from short faults. "Effects of current on human beings and livestock" (IEC 60479) defines a human body impedance model in electric shock conditions that consists of resistive components and capacitive components. Although the human body impedance model properly works in AC electricity, it does not well match with the electric shock behavior in DC electricity. In this study, the contradiction of the human body impedance model defined by IEC 60479 in case of DC electricity is shown through experiments for the human body. From the analysis of experimental results, a novel unified human body impedance model in electric shock conditions is proposed. This model consists of resistive components, capacitive components, and an inductance component. The proposed human impedance model matches well for AC and DC electricity environments in simulation and experiment.
New Control Method for the Current Ripple Reduction of 3-phase Interleaved Bidirectional DC-DC Converter
Jung, Jae-Hun ; Kim, Jihyun ; Nho, Eui-Cheol ; Kim, Heung-Geun ; Chun, Tae-Won ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 260~266
DOI : 10.6113/TKPE.2016.21.3.260
A new method for the current ripple reduction of a three-phase interleaved bidirectional DC-DC converter is proposed. The converter used in this study operates in discontinuous mode to minimize the switching losses. All the switches are turned on at ZVS and ZCS conditions, and turned off at ZVS condition. The charging and discharging power of the battery is controlled by varying the switching frequency while maintaining the discontinuous mode operation. A 3 kW 20 kHz power converter is designed and implemented. Simulation and experimental results show the validity of the proposed method. The proposed control method can be used to reduce the battery ripple current significantly.
Development of 50kW High Efficiency Fast Charger with Wide Charging Voltage Range
Park, Jun-Sung ; Kim, Min-Jae ; Jeong, Heon-Soo ; Kim, Joo-Ha ; Choi, Se-Wan ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 267~274
DOI : 10.6113/TKPE.2016.21.3.267
In this study, a fast charger for electric vehicle with wide charging voltage range is proposed. To achieve high efficiency, three-level topologies are employed for the AC-DC and DC-DC converters. Given that the output range of the DC-DC converter in fast chargers is quite wide, the circulating current of conventional three-level converter will increase under low voltage condition. The proposed hybrid switching method mitigates this issue. When a coupled inductor is used on the output side, the circulating current is further reduced, and the switches
achieve turning-off under the ZCS condition. Experimental results from a 50 kW prototype are provided to validate the proposed charger, and a rated efficiency of 95.9% is obtained.
Bidirectional Magnetic Wireless Communication System under Inductive Power Transfer capable of Amplitude-Shift Keying(ASK) Modulation Control
Choi, Byeung-Guk ; Lee, Eun-Soo ; Rim, Chun-Taek ;
The Transactions of the Korean Institute of Power Electronics, volume 21, issue 3, 2016, Pages 275~281
DOI : 10.6113/TKPE.2016.21.3.275
A novel bidirectional magnetic wireless communication system is proposed in this study. This system provides the communication capability between the source and load sides by high-frequency signal while wireless power is transferred. Contrary to the conventional wireless communication systems using complex IC circuit and active components, the proposed system is simply composed of passive components. It is practical and beneficial for environmental robustness, cost effectiveness, and simple implementation. The detailed static analysis of the proposed system for power and communication lines is established. The proposed system is experimentally verified, and results show that a 0.1 voltage gain for communication line is obtained while a 2.0 voltage gain for the power line is achieved. The proposed system is adequate for practical applications as it allows the inductive power transfer system to wirelessly and easily communicate between the source and load sides.