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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 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 Novel Control Method of Resistance Spot Welding Inverter using Dynamic Resistance Characteristics for Weld Quality Improvement
Kang, Sung-Kwan ; Jung, Jae-Hun ; Nho, Eui-Cheol ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 491~497
DOI : 10.6113/TKPE.2015.20.6.491
This study proposes a new control method for a resistance spot welding inverter to improve weld quality. The proposed method is based on the dynamic resistance characteristics of steel sheets to be welded. A point in the second peak value of the dynamic resistance occurs during one shot of the welding current flow. A constant voltage control is applied from zero to the peak point, and a constant current control is adopted from the peak point to the end of the shot. The mixed mode control of the constant voltage and current guarantees high weld quality. Experiments are conducted with a 5 kA power supply and 0.5 mm steel sheets to compare quality. Experimental results show that weld quality is improved more than 10 times that of the conventional control method.
A New PSIM Model for PV Panels Employing Datasheet-based Parameter Tuning
Park, Jun-Young ; Choi, Sung-Jin ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 498~508
DOI : 10.6113/TKPE.2015.20.6.498
In the simulation of photovoltaic (PV) power conditioning systems, PSIM is a widely accepted circuit simulation platform because of its fast speed and C-code support. PSIM provides two kinds of generic PV panel models: functional model and physical model. Whereas the functional model simulates PV in the standard test condition (STC) only, the physical model can emulate changing PV characteristics under varying temperatures and irradiation conditions and is thus more suitable for system simulation. However, the physical model requires complicated parameters from users, and thus it is prone to errors and is difficult to use. In this study, a new PSIM model for PV is presented to solve these problems. The proposed model utilizes manufacturers` datasheet values specified under STC only and excludes user-defined information from input parameters. To achieve good accuracy even in varying environmental conditions, single-diode model parameters are successively tuned to a time-varying virtual datasheet. Comparison with a conventional physical model shows that the proposed model provides more accurate simulation according to error analysis based on the EN50530 standard.
Overmodulation Characteristics of Carrier Based MVPWM for Eliminating the Leakage Currents in Three-Level Inverter
Lee, Eun-Chul ; Choi, Nam-Sup ; Ahn, Kang-Soon ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 509~516
DOI : 10.6113/TKPE.2015.20.6.509
The overmodulation characteristics of a carrier-based medium vector pulse width modulation (CBMVPWM) are examined in this study. CBMVPWM can completely eliminate leakage currents in a three-phase, three-level inverter using only the switching states with the same common mode voltage even in an overmodulation operation. The analytic equations for the magnitude of the output voltage and the switching frequency are derived for overmodulation operation, and the effect of dead time on the leakage current is demonstrated. This study presents the operating principle of CBMVPWM, basic overmodulation features, and simulations and experiments for operating verification.
Stationary Reference Frame Voltage Controller for Single Phase Grid Connected Inverter for Stand Alone Mode
Hong, Chang-Pyo ; Kim, Hag-Wone ; Cho, Kwan-Yuhl ; Lim, Byoung-Kuk ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 517~525
DOI : 10.6113/TKPE.2015.20.6.517
A grid connected inverter must be operated as the main electricity source under an isolated condition caused by the grid problem. Conventionally, the dual loop controller is used for the grid inverter, and the controller is used for control under the stand-alone mode. Generally, the PI(Proportional - Integral) controller is highly efficient under a synchronous reference frame, and stable control can be available. However, in this synchronous frame-based control, high-quality DSP is required because many sinusoidal calculations are necessary. When the PI control is conducted under a stationary frame, the controller constructions are made simple so that they work even with a low-price micro controller. However, given the characteristics of the PI controller, it should be designed with the phase of reference voltage considered. Otherwise, the phase delay of the output voltage can occur. Although the current controller also has a higher bandwidth than the voltage controller, distortion of the voltage is difficult to avoid only by the rapid response of the PI controller, as a sudden load change can occur in the nonlinear load. In this study, a new control method that solves the voltage controller bandwidth problem and rapidly copes with it even in the nonlinear load situation is proposed. The validity of the proposed method is proved by simulation and experimental results.
Equivalent Grid Impedance Estimation Method Using Negative Sequence Current Injection in Three-Phase Grid-connected Inverter
Park, Chan-Sol ; Song, Seung-Ho ; Im, Ji-Hoon ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 526~533
DOI : 10.6113/TKPE.2015.20.6.526
A new algorithm is proposed for the estimation of equivalent grid impedance at the point of common coupling of a grid-tie inverter output. The estimated impedance parameter can be used for the improvement of the performance and the stability of the distributed generation system. The estimation error is inevitable in the conventional estimation method because of the axis rotation due to PLL. In the conventional estimation error, the d-q voltage and current are used for the calculation of the impedance with active and reactive current injections. Conversely, in the proposed algorithm, the negative sequence current is injected, and then the negative sequence voltage is measured for the impedance estimation. As the positive and negative sequence current controller is independent and the PLL is based on the positive sequence component only, the estimation of the equivalent impedance can be achieved with high accuracy. Simulation and experimental results are compared to validate the proposed algorithm.
Modelling Voltage Variation at DC Railway Traction Substation using Recursive Least Square Estimation
Bae, Chang-Han ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 534~539
DOI : 10.6113/TKPE.2015.20.6.534
The DC overhead line voltage of an electric railway substation swings depending on the accelerating and regenerative-braking energy of trains, and it deteriorates the energy quality of the electric facility in the DC railway substation and restricts the powering and braking performance of subway trains. Recently, an energy storage system or a regenerative inverter has been introduced into railway traction substations to diminish both the variance of the overhead line voltage and the peak power consumption. In this study, the variance of the overhead line voltage in a DC railway substation is modelled by RC parallel circuits in each feeder, and the RC parameters are estimated using the recursive least mean square (RLMS) scheme. The forgetting factor values for the RLMS are selected using simulated annealing optimization, and the modelling scheme of the overhead line voltage variation is evaluated through raw data measured in a downtown railway substation.
A Novel Islanding Detection Scheme without Non Detection Zone
Jo, Yeong-Min ; Kim, Dong-Gyun ; Cho, Sang-Yoon ; Song, Seung-Ho ; Choy, Ick ; Lee, Young-Kwoun ; Choi, Ju-Yeop ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 540~549
DOI : 10.6113/TKPE.2015.20.6.540
Unintentional islanding results in safety hazards, reliability, and many other issues. Therefore, the islanding detection of a power conditioning system of a distributed generation, such as a grid-connected photovoltaic inverter, is a key function for standard compliance. Currently, many anti-islanding schemes have been examined, but existing anti-islanding schemes have poor power quality and non-detection zone issues. Therefore, this study analyzes the non-detection zone in a more deliberate manner than the existing analysis of the non-detection zone and proposes a new anti-islanding scheme, which has negligible power quality degradation and no non-detection zone. Simulation and experimental results validate that the proposed scheme shows much better performance than other existing schemes.
A Strategy of Increasing the Wind Power Penetration Limit with VSC Type MMC-HVDC in Jeju Power System
Lee, Seungmin ; Kim, Eel-Hwan ; Kim, Ho-Min ; Chae, Sang-Heon ; Quach, Ngoc-Thinh ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 550~557
DOI : 10.6113/TKPE.2015.20.6.550
The Jeju Special Self-Governing Province is currently promoting the "Carbon-free Island by 2030" policy, which requires the use of renewable energy instead of fossil fuel so that the island will have no carbon gases generated by 2030. To implement this policy, the island plans to build a wind power plant capacity of 1.09 GW in 2020; this wind power plant is currently ongoing. However, when wind power output is greater than the power demand of the island, the stability of Jeju Island power system must be prepared for it because it can be a problem. Therefore, this study proposes a voltage source-type MMC-HVDC system linked to mainland Korea to expand the wind power penetration limits of Jeju Island under the stable operation of the Jeju Island power system. To verify the effectiveness of the proposed scheme, computer simulations using the PSCAD/EMTDC program are conducted, and the results are demonstrated. The scenarios of the computer simulation consist of two cases. First, the MMC-HVDC system is operated under variable wind power in the Jeju Island power system. Second, it is operated under the predicted Jeju Island power system in 2020.
Implementation and Problem Analysis of Phase Shifted dc-dc Full Bridge Converter with GaN HEMT
Joo, Dong-Myoung ; Kim, Dong-Sik ; Lee, Byoung-Kuk ; Kim, Jong-Soo ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 558~565
DOI : 10.6113/TKPE.2015.20.6.558
Gallium nitride high-electron mobility transistor (GaN HEMT) is the strongest candidate for replacing Si MOSFET. Comparing the figure of merit (FOM) of GaN with the state-of-the-art super junction Si MOSFET, the FOM is much better because of the wide band gap characteristics and the heterojunction structure. Although GaN HEMT has many benefits for the power conversion system, the performance of the power conversion system with the GaN HEMT is sensitive because of its low threshold voltage (
) and even lower parasitic capacitance. This study examines the characteristics of a phase-shifted full-bridge dc-dc converter with cascode GaN HEMT. The problem of unoptimized dead time is analyzed on the basis of the output capacitance of GaN HEMT. In addition, the printed circuit board (PCB) layout consideration is analyzed to reduce the negative effects of parasitic inductance. A comparison of the experimental results is provided to validate the dead time and PCB layout analysis for a phase-shifted full-bridge dc-dc converter with cascode GaN HEMT.
The Design and Applications of LCC Resonant Converter
Ahn, Suk-Ho ; Jang, Sung-Roc ; Ryoo, Hong-Je ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 566~572
DOI : 10.6113/TKPE.2015.20.6.566
This study introduces an LCC resonant converter operating on a continuous conduction mode. The LCC resonant converter has the advantage of improving system efficiency, especially under the rated load condition, because it can reduce conduction loss by improving the resonance current shape and switching loss by increasing the lossless snubber capacitance. The proposed LCC resonant converter is applied to various applications, including a 60 kW EV fast charger, a 24 kJ/s high-voltage capacitor charger, and a 20 kV, 20 kW high-precision DC power supply. Experimental results prove that the proposed LCC resonant converter topology can be effectively used as a converter topology for these applications.
Control Algorithm of Thyristor Dual Converter Power System for Railway Power Substations
Han, Sung-Woo ; Lee, Chang-Hee ; Kim, Young-Woo ; Moon, Dong-Ok ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 573~579
DOI : 10.6113/TKPE.2015.20.6.573
A control algorithm of thyristor dual converter power system is proposed in this study for a railway power substation. The thyristor dual converter can use regenerative power without an additional system using control algorithm. An autonomous voltage and mode change method is also proposed to provide uninterrupted power to the railway. A 10 kW reduced model of the thyristor dual converter power system is built and tested to verify the validity of the proposed control algorithm.
A Verification of a Sensorless BLDC Motor Drive System to Control 4-axis Fins for a Guided Artillery Munition by HILS
Lee, Tae-Hyung ; Kim, Sang-Hoon ; Cho, Chang-Yeon ; Pak, Chang-Ho ; Kim, Jae-Ho ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 6, 2015, Pages 580~586
DOI : 10.6113/TKPE.2015.20.6.580
A brushless DC (BLDC) motor control system for four-axis driving fins to control the flight attitude of a guided artillery munition is developed in this study. This system adopts a simple sensorless control scheme without a Hall sensor. A 12-step driving sensorless BLDC motor scheme is used to improve the output torque. This system has many restrictive problems that hinder the verification of a real system. For example, this has cost and environmental limitations. Therefore, this study develops HILS to verify a four-axis driving fin control system and verifies the position control system hardware by HILS operation.