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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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The Korean Institute of Power Electronics
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Volume & Issues
Volume 20, Issue 6 - Dec 2015
Volume 20, Issue 5 - Oct 2015
Volume 20, Issue 4 - Aug 2015
Volume 20, Issue 3 - Jun 2015
Volume 20, Issue 2 - Apr 2015
Volume 20, Issue 1 - Feb 2015
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A Study on Current Ripple Reduction Due to Offset Error and Dead-time Effect of Single-phase Grid-connected Inverters Based on PR Controller
Seong, Ui-Seok ; Hwang, Seon-Hwan ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 201~208
DOI : 10.6113/TKPE.2015.20.3.201
The effects of dead-time and offset error, which cause output current distortion in single-phase grid-connected inverters are investigated this paper. Offset error is typically generated by measuring phase current, including the voltage unbalance of analog devices and non-ideal characteristics in current measurement paths. Dead-time inevitably occurs during generation of the gate signal for controlling power semiconductor switches. Hence, the performance of the grid-connected inverter is significantly degraded because of the current ripples. The current and voltage, including ripple components on the synchronous reference frame and stationary reference frame, are analyzed in detail. An algorithm, which has the proportional resonant controller, is also proposed to reduce current ripple components in the synchronous PI current regulator. As a result, computational complexity of the proposed algorithm is greatly simplified, and the magnitude of the current ripples is significantly decreased. The simulation and experimental results are presented to verify the usefulness of the proposed current ripple reduction algorithm.
Protective Insulation Monitoring Device in IT Earth Systems
Kim, Yong-Jung ; Kim, Hyosung ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 209~213
DOI : 10.6113/TKPE.2015.20.3.209
With the increasing popularity of renewable generation systems and the advancement of power electronics, DC distribution systems have recently received considerable research attention. DC distribution has numerous advantages, including reliability, power quality, and efficiency. Owing to these advantages, DC distribution has been applied to data centers and power quality-sensitive electronic load conditions. Because grounding electrodes in DC are much more susceptible to corrosion than in AC, the IT system defined in IEC Standard 60364 may be a good candidate for an earthing method for DC distribution systems. In addition, IEC Standard 61557 specifies the requirements for insulation monitoring devices (IMD) for protection of the IT system, which continuously monitors the insulation resistances between the power lines and the earth. This paper discusses the development and evaluation of IMD to promote the reliability of distribution systems and increase safety of humans and facilities.
Totem-pole Bridgeless Boost PFC Converter Based on GaN FETs
Jang, Paul ; Kang, Sang-Woo ; Cho, Bo-Hyung ; Kim, Jin-Han ; Seo, Han-Sol ; Park, Hyun-Soo ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 214~222
DOI : 10.6113/TKPE.2015.20.3.214
The superiority of gallium nitride FET (GaN FET) over silicon MOSFET is examined in this paper. One of the outstanding features of GaN FET is low reverse-recovery charge, which enables continuous conduction mode operation of totem-pole bridgeless boost power factor correction (PFC) circuit. Among many bridgeless topologies, totem-pole bridgeless shows high efficiency and low conducted electromagnetic interference performance, with low cost and simple control scheme. The operation principle, control scheme, and circuit implementation of the proposed topology are provided. The converter is driven in two-module interleaved topology to operate at a power level of 5.5 kW, whereas phase-shedding control is adopted for light load efficiency improvement. Negative bias circuit is used in gate drivers to avoid the shoot-through induced by high speed switching. The superiority of GaN FET is verified by constructing a 5.5 kW prototype of two-module interleaved totem-pole bridgeless boost PFC converter. The experiment results show the highest efficiency of 98.7% at 1.6 kW load and an efficiency of 97.7% at the rated load.
High Efficiency LED Driving System using Y type Current Balancing Transformer
Kim, Jin-Gu ; Yoo, Jin-Wan ; Park, Chong-Yeon ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 223~231
DOI : 10.6113/TKPE.2015.20.3.223
LEDs have been widely used in lighting displays, automobiles, and airplanes owing to their excellent light output characteristics and long lifespan. Though LEDs are manufactured under the same process, variations in impurity concentrations cause electrical deviation among LEDs. The resulting electrical deviation can not only reduce the life time of the LED but also cause non-uniform luminance of LEDs connected in parallel. LED driving circuit is required to solve these problems. In this paper, we propose a LED driving system using Y-type current balancing transformer to maximize the efficiency of the system by removing output stage Schottky diodes. Experimental results are presented to verify the performance of proposed LED driving system that is applied to 80 W LED modules.
Sensorless Control of BLDC Motor using d-q Synchronously Rotating Reference Frame Concept
Moon, Jong-Joo ; Heo, Hong-Jun ; Kim, Jang-Mok ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 232~238
DOI : 10.6113/TKPE.2015.20.3.232
A sensorless control algorithm of brushless DC (BLDC) motors with a model current based on 120 degree conduction mode is proposed in this paper. The rotor speed and position can be estimated using the current model of BLDC motor, which is a modified version of the conventional current model of permanent magnet synchronous motor. The rotor speed and position can be obtained using the difference of the actual current and the model current. The position error caused by the parameter errors of the model current is compensated using a PI controller and the feedback loop of the real current. The validity of the proposed sensorless control algorithm is verified through simulation.
A Novel Control Algorithm of a Three-phase PWM Inverter with LC Filter
Kim, Kwang-Seob ; Hyun, Dong-Seok ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 239~246
DOI : 10.6113/TKPE.2015.20.3.239
A novel control method of a three-phase PWM inverter with LC filter is proposed. The transfer function of LC filter is the same as that of second-order low pass filter(LPF), which has a zero damping ratio. A simple method of implementing second-order LPF with damping ratio is to add a resistor in an LC circuit. However, in a real power system, adopting damping resistors is impractical because it results in losses proportional to the square of the current flowing through the resistors. Instead of inserting resistors, the proposed control strategy utilizes the measured capacitor voltages to control the oscillation of LC circuit. The overall transfer function of the proposed method is the same as a second-order LPF, and its damping ratio is controllable via control variables. The current controller can have overshoots caused by LC filter. Improved current controller is implemented by an equivalent second-order of LC filter. A 7.5 kVA PWM converter and a PWM inverter with a 5.5 kW induction motor are set up to verify the proposed control algorithm. Test waveforms are also presented to verify the proposed LC filter control algorithm.
Analysis of Anti-Islanding Schemes using Frequency Drift in Distributed Generation System
Jo, Yeong-Min ; Cho, Sang-Yoon ; Song, Seung-Ho ; Choy, Ick ; Choi, Ju-Yeop ; Lee, Young-Kwoun ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 247~254
DOI : 10.6113/TKPE.2015.20.3.247
Unintentional islanding results in safety hazards, power quality degradation, and many other issues. Thus, islanding detection of grid-connected distributed generation system is a key function for standards compliance. Many anti-islanding schemes are currently being studied; however, existing anti-islanding schemes used in inverters have power quality degradation and non-detection zone issues. Therefore, this paper analyzes existing anti-islanding schemes by using frequency drift in accordance with both islanding detection performance and power quality. This paper also proposes a new anti-islanding scheme by using frequency drift. Both simulation and experimental results show that the proposed scheme has negligible power quality degradation and no non-detection zones compared with other existing schemes.
Analysis of Interleaving Effect for Toroidal Type Transformer Windings
Shin, Kyoung-Gu ; Kang, Byeong-Geuk ; Chung, Se-Kyo ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 255~261
DOI : 10.6113/TKPE.2015.20.3.255
An analysis of the interleaving effect for the secondary winding distribution of a toroidal transformer is presented in this paper. The equations to calculate the leakage inductance of the toroidal transformer are derived using MMF diagrams for the different secondary winding distributions. The simulation and experimental results are provided to show the validity of the theoretical calculation.
AC-DC Converter using the PFC Inductor and LLC Resonant Transformer with an Integrated Magnetic Core
Noh, Young-Jae ; Kang, Cheol-Ha ; Saran, Meas ; Kim, Eun-Soo ; Won, Jong-Seob ; Kim, Dong-Hee ; Lee, Young-Soo ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 262~272
DOI : 10.6113/TKPE.2015.20.3.262
An integrated two-in-one transformer applicable to PSUs for a 120 W LED TV is proposed. This transformer comprises a PFC inductor and an LLC transformer placed and integrated on an E-I-E type magnetic core. Performance is evaluated by observing the coupling coefficients of the proposed two-in-one transformer under various air gap topologies. Among the topologies studied, an integrated transformer with centered air gap shows stable operational characteristics with a minimized mutual coupling (interference). Furthermore, applicability of the proposed integrated transformer to PSUs for a 120 W LED TV is studied from the viewpoint of integrating different magnetic components into one core, resulting to low weight, low cost, and high power density.
Optimal Zero Vector Selecting Method to Reduce Switching Loss on Model Predictive Control of VSI
Park, Jun-Cheol ; Park, Chan-Bae ; Baek, Jei-Hoon ; Kwak, Sang-Shin ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 273~279
DOI : 10.6113/TKPE.2015.20.3.273
A zero vector selection method to reduce switching losses for model predictive control (MPC) of voltage source inverter is proposed. A conventional MPC of voltage source inverter has not been proposed, and a method to select the redundancy of the zero vector is required for this study. In this paper, the redundancy of the zero vectors is selected with generating a zero sequence voltage to reduce switching losses. The zero vector of 2-level inverter is determined by determining sign of the zero sequence voltage. In the proposed method, the quality of the current is retained and switching loss can be reduced compared with the conventional method. This result was verified by P-sim simulation and experiments.
High-Efficiency Full-Bridge DC-DC Converter with Current-Doubler Rectifier with Asymmetric Pulse-Width Modulation
Yang, Min-Kwon ; Choi, Woo-Young ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 280~289
DOI : 10.6113/TKPE.2015.20.3.280
A high-efficiency full-bridge DC-DC converter with a current-doubler rectifier and an asymmetric pulse-width modulation is proposed. Through the asymmetric pulse-width modulation, the proposed converter achieves zero-voltage switching of power switches without the circulating currents. The proposed converter reduces the output current ripple through the current-doubler rectifier. A control strategy is suggested for the proposed converter to charge battery banks. A constant current and constant voltage charging is performed. The proposed converter achieved a higher efficiency compared with the conventional full-bridge DC-DC converter with a phase-shift modulation. The performance of the proposed converter is evaluated by the experimental results for a 1.0 kW prototype circuit.
Reactive Power Compensator for Pulsed Power Electric Network of International Thermonuclear Experimental Reactor
Jo, Hyunsik ; Jo, Jongmin ; Cha, Hanju ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 3, 2015, Pages 290~295
DOI : 10.6113/TKPE.2015.20.3.290
Analysis and verification of reactive power compensator (RPC) for ITER pulsed power electric network (PPEN) are described in this paper. The RPC system is rated for a nominal power of 250 Mvar necessary to comply with the allowable reactive power limit value from the grid 200 Mvar. This system is currently under construction and is based on static var compensation technology with a thyristor-controlled reactor and a harmonic filter. The RPC minimizes reactive power from grid using prediction of reactive power consumption of AC-DC converters. The feasibility of the reactive power compensation was verified by assembling a real controller and implementing ITER PPEN in the real time digital simulator for the hardware-in-loop facility. When maximum reactive power is reached, grid voltage is stabilized and maximum reactive power decreased from 120 Mvar to 40 Mvar via the reactive power prediction method.