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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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Series-connected Power Conversion System Integrating a Photovoltaic Power Conditioner with a Charge-balancing Circuit
Lee, Hyun-Jun ; Shin, Jong-Hyun ; Park, Joung-Hu ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 389~394
DOI : 10.6113/TKPE.2015.20.5.389
This paper proposes a series-connected power conversion system that integrates a photovoltaic power conditioner and a charge-balancing circuit. In conventional methods, a photovoltaic power conditioner and a cell-balancing circuit are needed for photovoltaic systems with energy storage devices, which results in a complex configuration and high cost. To overcome these problems, a series-connected DC-DC power conditioning system that integrates a photovoltaic power conditioner with a charge-balancing circuit is proposed. During the generation, the system operates as power conditioner only, whereas it operates as a cell balancing circuit during the rest time. For the analysis, the operating principle of the circuit and the controller design are done by PSIM simulation. For verification, a hardware prototype with 48-W photovoltaic modules has been implemented. Results verified that the modularized photovoltaic power conversion system with a series-connected storage successfully works with the proposed method.
Bidirectional Tapped-inductor Boost-Flyback Converter
Kim, Hyun-Woo ; Jeon, Young-Tae ; Park, Joung-Hu ; Jeon, Hee-Jong ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 395~401
DOI : 10.6113/TKPE.2015.20.5.395
This paper proposes a new bidirectional DC-DC converter with high efficiency. The proposed converter is composed of a flyback and a tapped-inductor boost converter to satisfy extreme operating conditions with low cost. The outputs are connected in series to achieve a high-voltage step-up. In the reverse direction, the proposed converter has an extreme step-down voltage. In this study, the proposed converter was employed with a 100 W hardware prototype. To design the controller, a small-signal transfer function of the proposed converter is derived. For PV power conditioning systems, a maximum power point tracking method is applied with perturb and observe method. To verify the operation of the bidirectional power flow, the current controller is applied. All of the controllers are employed with a digital signal processor.
A Novel Rotor Position Error Calculation Method using a Rotation Matrix for a Switching Frequency Signal Injected Sensorless Control in IPMSM
Kim, Sang-Il ; Kim, Rae-Young ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 402~409
DOI : 10.6113/TKPE.2015.20.5.402
This paper proposes a novel rotor position error calculation method for high-frequency signal-injected sensorless control. The rotor position error using the conventional modulation method can be only measured up to
. In addition, when the rotor position estimation error is not sufficiently small, the small angle approximation in no longer valid. To overcome these problems, this study introduces a new rotor position error calculation method using the rotating matrix. In this study, the position error measurement range of the proposed method is extended from
. The linearity between the real rotor position error and the estimated error is maintained by nearly
. These features of the proposed method improve the performance of the sensorless control. The validity of the proposed method is verified by simulations and experiments.
Comparison of Efficiency for Voltage Source and Current Source Based Converters in 5MW PMSG Wind Turbine Systems
Kang, Tahyun ; Kang, Taewon ; Chae, Beomseok ; Lee, Kihyun ; Suh, Yongsug ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 410~420
DOI : 10.6113/TKPE.2015.20.5.410
This paper provides a comparison of power converter loss and thermal description for voltage source and current source type 5 MW-class medium-voltage topologies of wind turbines. Neutral-point clamped three-level converter is adopted for a voltage source type topology, whereas a two-level converter is employed for current source type topology, considering the popularity in the industry. To match the required voltage level of 4160 V with the same switching device of IGCT as in the voltage source converter, two active switches are connected in series for the case of current source converter. Transient thermal modeling of a four-layer Foster network for heat transfer is done to better estimate the transient junction and case temperature of power semiconductors during various operating conditions in wind turbines. The loss analysis is confirmed through PLECS simulations. Comparison result shows that the VSC-based wind turbine system has higher efficiency than the CSC under the rated operating conditions.
A DTC-PWM Control Scheme of PMSM using an Approximated Voltage Function of Voltage Vector
Kwak, YunChang ; Lee, Dong-Hee ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 421~428
DOI : 10.6113/TKPE.2015.20.5.421
An advanced direct torque control (DTC) with pulse width modulation (PWM) method is presented in this paper. The duty ratio calculation of the selected voltage vector is based on the voltage functions of the selected voltage vector according to the sector angle. The proposed DTC uses a conventional DTC scheme with six sector divisions and switching rules. However, the winding voltages are supplied by the PWM approach. Furthermore, the duty ratio of the switching voltage vector is determined by the flux, torque error, and motor speed. The base voltage that shall determine the duty ratio can be calculated by approximate voltage functions according to the voltage angle. For the calculation of base voltages, second-order quadratic functions are used to express the output voltage of the selected voltage vector according to voltage angle. The coefficients for the second-order quadratic functions are selected by the voltage vector, which is determined by the switching rules of the DTC. In addition, the voltage functions are calculated by the coefficients and voltage angle between the voltage vector and rotor position. The switching voltages from the calculated duty ratio can supply the proper torque and flux to reduce the ripple and error. The proposed control scheme is verified through practical experimental comparisons.
Torque Ripple Reduction Algorithm of PM Synchronous Motor at High Speed Operation
Kim, Jong-Hyun ; Cho, Kwan-Yuhl ; Kim, Hag-Wone ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 429~436
DOI : 10.6113/TKPE.2015.20.5.429
Torque ripples generate mechanical vibration at low speed and acoustic noise at high speed. The back emf harmonics of a PM synchronous motor is one of the main sources of torque ripples. To reduce torque ripples resulting from back emf harmonics, dq-axis harmonic currents that reduce the torque ripples are generally compensated to the current controller. Harmonic current compensation is effective at low speed, but it is not applicable at high speed because of the limited bandwidth of the current controller. In this study, dq-axis harmonic voltage compensation that can reduce torque ripples at high speed is proposed. The dq-axis harmonic voltages are calculated from the motor speed and the dq-axis harmonic currents. The effectiveness of the proposed method in reducing torque ripple is verified by a simulation and experiments.
An Integrated Transformer-based LED Power Supply with Wide-Output-Voltage Control
Kang, Cheol-Ha ; Ju, Jong-Seong ; Kim, Eun-Soo ; Won, Jong-Seob ; Lee, Young-Soo ; Kim, Dong-Hee ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 437~447
DOI : 10.6113/TKPE.2015.20.5.437
In this paper, implementation of an integrated transformer applicable to power supply units (PSUs) for a 150-W LED with a wide range of output voltage is presented. The transformer is comprised of a PFC inductor and an LLC resonant transformer, each of which is placed and integrated on an E-I-E-type magnetic core. Integrated transformers with two different air gap topologies (i.e., the side and center gap topologies) are considered in the design phase to investigate their applicability. The design consideration on the LLC resonant converter used for the wide-output-voltage control ranges is described, and the overall performance of the proposed system is verified through realization of it onto a 150-W LED PSU board.
An Algorithm for Even Distribution of Loss, Switching Frequency, Power of Model Predictive Control Based Cascaded H-bridge Multilevel Converter
Kim, I-Gim ; Kwak, Sang-Shin ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 448~455
DOI : 10.6113/TKPE.2015.20.5.448
A model predictive control (MPC) method without individual PWM has been recently researched to simplify and improve the control flexibility of a multilevel inverter. However, the input power of each H-bridge cell and the switching frequency of switching devices are unbalanced because of the use of a restricted switching state in the MPC method. This paper proposes a control method for balancing the switching patterns and cell power supplied from each isolated dc source of a cascaded H-bridge inverter. The supplied dc power from isolated dc sources of each H-bridge cells is balanced with the proposed cell balancing method. In addition, the switching frequency of each switching device of the CHB inverter becomes equal. A simulation and experimental results are presented with nine-level and five-level three-phase CHB inverter to validate the proposed balancing method.
New Design of a Permanent Magnet Linear Synchronous Motor for Seamless Movement of Multiple Passive Carriers
Lee, Ki-Chang ; Kim, Min-Tae ; Song, Eui-Ho ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 456~463
DOI : 10.6113/TKPE.2015.20.5.456
Nowadays, small quantity batch production, which is so-called a flexible manufacturing system, is a major trend in the modern factory automation industry. The demands for new transportation system are increased gradually, with which multiple passive carriers carrying materials and semi-products are precisely and individually controlled along a single closed rail. Thus, a new type of permanent magnet linear synchronous motor (PMLSM), which consists of state coils on a single rail and PM movers as many as carriers, is proposed in this paper. The rail can be segmented as modules with pairs of coils and a current amplifier, which makes the transportation system simple; therefore, the rail can be easily extended and repaired. A design method of the new PMLSM with a single carrier is proposed, which can be thought as a new version of PMLSM, a coil-segmented coreless PMLSM (CS-CLPMLSM). Experimental setup for it is made, and propulsion results show that with the help of a new effective coil selection and switching algorithms, the conventional current-based vector control is sufficient to fulfill the position and velocity control of the new PMLSM. The proposed PMLSM is expected to fulfill seamless servo-control of multiple carriers also in process line, such as a new generation of flat panel display manufacturing line.
A Non-Isolated 3-Level High Step-Up Boost Converter With Output Voltage Balancing
Yun, Song-Hyun ; Kang, Hyemin ; Cha, Honnyong ; Kim, Heung-Geun ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 464~470
DOI : 10.6113/TKPE.2015.20.5.464
In this paper, a non-isolated three-level high step-up boost converter with output voltage balancing is proposed. By adding one extra inductor to the conventional three-level boost converter, the proposed converter is derived. Compared with the traditional boost converter and the three-level boost converter, the proposed converter can obtain very high voltage conversion ratio, and the voltage and current stress of switching devices and diodes are reduced. A 2.7 kW prototype converter is built and tested to verify performances of the proposed converter.
Islanding Detection Technique using Wavelet Energy in Grid-Connected PV System
Park, Hae-Chan ; Kim, Il-Song ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 471~478
DOI : 10.6113/TKPE.2015.20.5.471
The new islanding detection method using wavelet energy is proposed in this paper. The proposed method is based on the autocorrelation of the wavelet energies, which is obtained from the high-frequency components of the grid voltage. It has the enhanced detection capabilities in the UV/OV/UF/OF region, which the conventional passive methods cannot obtain. The mathematical theories on the wavelet are presented, and the performance effectiveness is proved by the experimental results.
Research on the Analysis and Improvement of the Performance of the Phase-Shifted Full-Bridge Converter for Electric Vehicle Battery Charger Applications
Lee, Il-Oun ;
The Transactions of the Korean Institute of Power Electronics, volume 20, issue 5, 2015, Pages 479~490
DOI : 10.6113/TKPE.2015.20.5.479
The conventional phase-shifted full-bridge (PSFB) converter with an LC filter has been widely used for high-power applications of over 1.0 kW. However, the PSFB converter cannot obtain optimal power conversion efficiency during the battery charging in electric vehicle (EV) on-board battery charger applications because of its unique drawbacks, such as a large circulating current and very high voltage stress in the rectifier diodes. As a result, the converters with a capacitive filter, such as LLC resonant converters, replace the PSFB converter in the EV chargers. This study analyzes the problems of the PSFB converter for EV on-board charger applications in detail. Moreover, the newest converters based on the conventional PSFB converter are reviewed. On the basis of the reviews, new PSFB converter topologies are proposed for EV charger applications. The new topologies are formed by connecting the rectifier stage in the PSFB converter with the output of an LLC resonant converter in series. Many problems of the conventional PSFB converter for EV charger applications can be solved and the performance can be more improved because of this structure; this idea is confirmed by an experiment consisting of prototype battery chargers under the output voltage range of 250-450 Vdc at 3.3 kW.