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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 17, Issue 6 - Dec 2012
Volume 17, Issue 5 - Oct 2012
Volume 17, Issue 4 - Aug 2012
Volume 17, Issue 3 - Jun 2012
Volume 17, Issue 2 - Apr 2012
Volume 17, Issue 1 - Feb 2012
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DC link Ripple Voltage Compensation of a Single-phase Grid-Connected PV System
Lee, Jae-Geun ; Choi, Jong-Woo ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 377~387
DOI : 10.6113/TKPE.2012.17.5.377
A single-phase grid-connected PV system is known as suitable for housing of less than 3 kW. The DC link voltage in a single-phase PV system has necessarily twice component of fundamental wave. It makes high THD in the grid current. According to the problem, power quality is lower. Many engineers have studied about this problem. The most simple method is to use low pass filter on DC link voltage control. However it is affected by DC link voltage control bandwidth. If cutoff frequency is reduced to increase the performance of low pass filter, it also lowers DC link voltage control bandwidth. Second method is using band stop filter, it works good on steady state but not good on transient state. This paper proposes the new method for removing ripple voltage to get an exact current reference. It improves the responses on steady state and transient state. The performance was verified through computer simulation using MATLAB and actual experiments.
Sampler Model of P-type Current Mode Control Utilizing Low Pass Filter
Jung, Young-Seok ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 388~392
DOI : 10.6113/TKPE.2012.17.5.388
In this paper, a sampler model for the P-type current mode control employing low pass filter is proposed. Even though the frequency response of the compensator used in a P-type current mode control employing low pass filter is similar to that of P-type compensator, the sampler model has to be obtained from the method used in PI-type current mode control. In order to show the usefulness of the proposed method, prediction results of the proposed model are compared to those from the circuit level simulator, PSIM.
A Modularized Charge Equalizer Using the Magnetizing Energy of the Multi-Winding Transformer
Lim, Chang-Soon ; Hyun, Dong-Seok ; Kim, Rae-Young ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 393~400
DOI : 10.6113/TKPE.2012.17.5.393
The modularized equalizers normally use additional components among the modules in the long series-connected lithium-ion battery string. In these approaches, the overall systems are heavy, bulky, and high-priced. Furthermore, the losses related to additional components decrease the system efficiency. To avoid these problems, a modularized equalizer, which has no additional components among the modules, is required. This paper proposes a novel control scheme using the magnetizing energy of the multi-winding transformer for the module equalization. In this scheme, the high duty cycle is applied to the module where the voltage is higher than the reference voltage and the low duty cycle is applied to the module where the voltage is lower than the reference voltage. Due to the different duty cycle, more electric charges are transferred from high voltage module to the low voltage module during the turn-off switching interval. Using the proposed control scheme, the equalizer system does not suffer from the size, cost, and loss related to the modularization. The experimental results are provided to verify the effectiveness of the proposed modularized equalizer.
Simple On-line Elimination Strategy of Dead Time and Nonlinearity in Inverter-fed IPMSM Drive Using Current Slope Information
Park, Dong-Min ; Kim, Myung-Bok ; Kim, Kyeong-Hwa ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 401~408
DOI : 10.6113/TKPE.2012.17.5.401
A simple on-line elimination strategy of the dead time and inverter nonlinearity using the current slope information is presented for a PWM inverter-fed IPMSM (Interior Permanent Magnet Synchronous Motor) drive. In a PWM inverter-fed IPMSM drive, a dead time is inserted to prevent a breakdown of switching device. This distorts the inverter output voltage, resulting in a current distortion and torque ripple. In addition to the dead time, inverter nonlinearity exists in switching devices of the PWM inverter, which is generally dependent on operating conditions such as the temperature, DC link voltage, and current. The proposed scheme is based on the fact that the d-axis current ripple is mainly caused by the dead time and inverter nonlinearity. To eliminate such an influence, the current slope information is determined. The obtained current slope information is processed by the PI controller to estimate the disturbance caused by the dead time and inverter nonlinearity. The overall system is implemented using DSP TMS320F28335 and the validity of the proposed algorithm is verified through the simulation and experiments. Without requiring any additional hardware, the proposed scheme can effectively eliminate the dead time and inverter nonlinearity even in the presence of the parameter uncertainty.
A New On-Line Dead-Time Compensator for Single-Phase PV Inverter
Vu, Trung-Kien ; Lee, Sang-Hoey ; Cha, Han-Ju ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 409~415
DOI : 10.6113/TKPE.2012.17.5.409
This paper presents a new software-based on-line dead-time compensation technique for a single-phase grid-connected photovoltaic (PV) inverter system. To prevent a short circuit in the inverter arms, a switching delay time must be inserted in the pulse width modulation (PWM) signals. This causes the dead-time effect, which degrades the system performance around zero-crossing point of the output current. To reduce the dead-time effect around the zero-crossing point of grid current, a harmonic mitigation of grid current is used as an additional part of the synchronous frame current control scheme. This additional task mitigates the harmonic components caused by the dead-time from the grid current. Simulation and experimental results are shown to verify the effectiveness of the proposed dead-time compensation method in the single-phase grid-connected inverter system.
Low Power-loss Current Measurement Technique Using Resistive Sensor and Bypass Switch
Lee, Hwa-Seok ; Thayalan, I. Daniel Thena ; Park, Joung-Hu ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 416~422
DOI : 10.6113/TKPE.2012.17.5.416
This paper proposes a low power-loss current measurement using a resistor and bypass switch. Conventional current sensing method using a resistor has a disadvantage of power loss which degrades the efficiency of the entire systems. On the other hand, proposed measurement technique operating with bypass-switch connected in parallel with sensing resistor can reduce power loss significantly the current sensor. The propose measurement works for discrete-time sampling of current sensing. Even while the analog-digital conversion does not occur at the controller, the sensing voltage across the sensor still causes ohmic conduction loss without information delivery. Hence, the bypass switch bypasses the sensing current with a small amount of power loss. In this paper, a 90[W] prototype hardware has been implemented for photovoltaic MPPT experimental verification of the proposed low power-loss current measurement technique. From the results, it can be seen that PV power observation is successfully done with the proposed method.
An Adaptive Maximum Power Point Tracking Scheme Based on a Variable Scaling Factor for Photovoltaic Systems
Lee, Kui-Jun ; Kim, Rae-Young ; Hyun, Dong-Seok ; Lim, Chun-Ho ; Kim, Woo-Chull ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 423~430
DOI : 10.6113/TKPE.2012.17.5.423
An adaptive maximum power point tracking (MPPT) scheme employing a variable scaling factor is presented. A MPPT control loop was constructed analytically and the magnitude variation in the MPPT loop gain according to the operating point of the PV array was identified due to the nonlinear characteristics of the PV array output. To make the crossover frequency of the MPPT loop gain consistent, the variable scaling factor was determined using an approximate curve-fitted polynomial equation about linear expression of the error. Therefore, a desirable dynamic response and the stability of the MPPT scheme were maintained across the entire MPPT voltage range. The simulation and experimental results obtained from a 3 KW rated prototype demonstrated the effectiveness of the proposed MPPT scheme.
A Design of Power Circuit and LCL Filter for Switching Mode PV Simulator
Lee, Sung-Min ; Yu, Tae-Sik ; Kim, Hyo-Sung ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 431~437
DOI : 10.6113/TKPE.2012.17.5.431
PV simulators are essential equipment for testing power conditioning systems (PCS) which are one of an important part in PV generator systems, for testing before shipment. High dynamic PV simulator is required since MPPT(Maximum Power Point Tracking) test procedure has been established by EN50530 regulation recently. Most high quality PV simulator prevailed in the market is linear type which however has low efficiency. This paper proposes design guide lines for the power stage and LCL type filter cooperating with a switching mode PV simulator that shows high efficiency and very low power consumption. Proposed theory is verified by experiment.
Improved Transient Response of Distributed Energy Resources Inverters to PQ Control using Decoupling
Choi, Chul-Hoon ; Choi, Jong-Woo ; Lee, Chang-Hee ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 438~444
DOI : 10.6113/TKPE.2012.17.5.438
This paper deals with the active and reactive power control of Grid connected system. It was shown that active power and reactive power can be dependently controlled with two individually adaptable parameters. The two parameters are power angle and voltage magnitude. Transient state will occur with active or reactive power reference value variation. This paper presents a new control strategy for active and reactive power control of less interaction and improved transient response. The paper details the control technique by the mathematical and electrical network analysis of the methodology. The performance was verified through computer simulation using MATLAB Simulink and experiment.
The Metal Detection using Primary Current in Contact-less Power Supply
Kim, Yu-Seok ; Yu, Joo-Hee ; Kim, Choon-Sam ; Sung, Won-Ki ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 445~452
DOI : 10.6113/TKPE.2012.17.5.445
The impurity detection method applied to existing discriminated the normality(R, L, C) and impurity(Metal) load using mutual RFID/ID method in the contactless power supply in which the primary side and the secondary side are completely separation by using the contactless transformer. However, this kind of system is caused the high cost of the system and complexity of control. Therefore, in this paper was proposed the contact-less power transfer using the primary current that determine normality or impurity load by compare the primary current Amplitude to reference quantity value and design the 3[W] contact-less power transfer and conduct an experiment for demonstrate the validity.
Designing Impedance Network at Quasi Z-Source Inverters by Considering ESR in the Capacitor
Yang, Jong-Ho ; Chun, Tae-Won ; Lee, Hong-Hee ; Kim, Heung-Geun ; Nho, Eui-Cheol ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 453~460
DOI : 10.6113/TKPE.2012.17.5.453
This paper proposes the method to design the parameters of an impedance network at three-phase QZSI(quasi Z-source inverter) by considering an equivalent series resistance (ESR) in the capacitor. The equations of both two capacitor voltages and two inductor currents are derived at three operating modes of the QZSI. The capacitor voltage ripples caused by the ESR in the capacitor at the transition state of operating modes are calculated. Based on the ripples of both the capacitor voltages and inductor currents, the optimal values of capacitor and inductor are designed. The simulation studies using PSIM and experimental results with DSP are carried out to verify the performance of design method.
Design of LLC Resonant Converter having Enhanced Load Range for Communication Power
So, Byong-Chul ; Seo, Ki-Bong ; Lee, Dong-Hoo ; Jung, Ho-Chul ; Hwang, Soon-Sang ; Kim, Hag-Wone ; Cho, Kwan-Yuhl ; Lim, Byung-Kuk ;
The Transactions of the Korean Institute of Power Electronics, volume 17, issue 5, 2012, Pages 461~469
DOI : 10.6113/TKPE.2012.17.5.461
This paper deals with LLC resonant converter for communication power supply. Generally, the load range of communication power is very wide. However, voltage conversion ratio of LLC converter is highly dependent of load condition. So, it is not easy to design of robust power supply along with the wide load condition. Especially, it is not possible to meet the required low voltage conversion ratio for low output voltage with high input voltage under the light load condition. To solve this problem, in this paper, a new duty control interlinked with operational frequency has been proposed. To prove the usefulness of the proposed control method, the simulation and experiments were carried out. The simulation and experimental results show the usefulness of the proposed control method.