• Journal of Power Electronics
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• v.19 no.6
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• pp.1477-1485
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• 2019

This paper proposes an effective model predictive current control (MPCC) that involves using 10 virtual voltage vectors to reduce the current harmonics and common-mode voltage (CMV) for a two-level five-phase voltage source inverter (VSI). In the proposed scheme, 10 virtual voltage vectors are included to reduce the CMV and low-order current harmonics. These virtual voltage vectors are employed as the input control set for the MPCC. Among the 10 virtual voltage vectors, two are applied throughout the whole sampling period to reduce current ripples. The two selected virtual voltage vectors are based on location information of the reference voltage vector, and their duration times are calculated using a simple algorithm. This significantly reduces the computational burden. Simulation and experimental results are provided to verify the effectiveness of the proposed scheme.

• Journal of Korean Vacuum Science & Technology
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• v.6 no.2
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• pp.55-57
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• 2002

Metal-vapor-vacuum-arc ion source is an ideal source for both high current metal ion implanter and high current plasma thin-film deposition systems. It uses the direct evaporation of metal from surface of cathode by vacuum arc to produce a very high flux of ion plasmas. The MEVVA ion source, the high-current metal-ion implanter and high-current magnetic-field-filtered plasma thin-film deposition systems developed in Beijing Normal University are introduced in this paper.

• Journal of Power Electronics
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• v.17 no.1
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• pp.172-180
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• 2017

The repetitive control (RC) strategy is widely used in AC power systems because of its high performance in tracking period signal and suppressing steady-state error. However, the dynamic response of RC is determined by the fundamental period delay $T_0$ existing in the internal model. In the current study, a ($nk{\pm}i$)-order harmonic RC structure is proposed to improve dynamic performance. The proposed structure has less data memory and can improve the tracking speed by n/2 times. $T_0$ proves the effectiveness of the ($nk{\pm}i$)-order RC strategy. The simulation and experiments of ($6k{\pm}1$)-order and ($4k{\pm}1$)-order RC strategy used in the voltage source inverter is conducted in this study to control the harmonic current source, which shows the validity and advantages of the proposed structure.

• Journal of the Korean Society of Safety
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• v.21 no.6 s.78
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• pp.26-32
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• 2006

The paper considers the electrical shock risk of the human body due to underwater leakage current in electric field. The characteristics of electric shock in fresh water due to the leakage of submerged electric facility in the bathtub in public baths were conducted. The exposed live electrode is modeled as a point source of electric current source. It is assumed that divergent monopole field exists in the vicinity of the current source, regardless of the presence of return electrode and insulating boundary. The electric potentials in the steel bathtub, Diesen and Mole and Flux3D program one are measured according to the distance from leakage source. The results show that the increased shock risk and safe distance are estimated by the bathtub of limited width and the voltage calculated on the basis of a divergent monopole field concept is compared with the measured value.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.6
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• pp.280-288
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• 2000

Recently, there has been growing interest in utilizing cogeneration(COGN) systems with a high-energy efficiency due to the increasing energy consumption and the lacking of energy resource. But an insertion of COGN system to existing power distribution system can cause several problems such as voltage variations, harmonics, protective coordination, increasing fault current etc, because of reverse power of COGN, especially in protective coordination. A study on a proper coordination with existing one is being required. The existing power distribution system is operated with radial type by one source and protection system is composed based on unidirectional power source. But an Insertion of COGN system to power distribution system change existing unidirectional power source system to bidirectional power source. Therefore, investigation to cover whole field of power distribution system must be accomplished such as changing of protection devices rating by increasing fault current, reevaluation of protective coordination. In this paper, simulation using PSCAD/EMTDC was accomplished to analyze effect of COGIN on distribution fault current. Also, the existing protection system of 22.9[kV] power distribution system and customers protection system to protect of COGIN was analyzed and the study on protective coordination between of two protection system accomplished.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.255-257
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• 1994

The V/F slip frequency constant control methods are used for driving induction motor with load commutated current source inverter, that is. constant V/F and slip frequency driving is used to load commutate the inverter below the critical frequency, while constant voltage and variable frequency and slip frequency driving are used in above the critical region. In order to applicate the load commutated current source inverter to the general use, speed control range of induction noter is selected to two times at rated frequency. Therefore, economical application is possible because of the maximum reduction of the condenser of the inverter output port. The use of the proposed force commutated circuit improves the false operation of force commutated circuit and inverter commutation failure which are produced by the influence of the lower-order harmonics of the conventional load commutated current source inverter at starting.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.196-199
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• 2001

This paper deals with current harmonics and unbalanced source voltages compensation using combined filter system. Filter system consists of a series active filter and parallel passive filters. Passive filters were a traditional method to compensate current harmonics, so those were installed in power system widely. The active filter can be a substitution to improve filtering characteristics and complement drawbacks of the passive filter. The combined system of the active power filter and passive filter can has a better compensation performances and economical goods. The series type active power filter injects compensation voltage into power system by transformers. It's compensation principle is able to applicate for voltage compensation. A new control algorithm for series active filter to compensate current harmonics and unbalanced source voltages is proposed. In the proposed algorithm, a compensation voltage for harmonic reduction is calculated directly by instantaneous reactive power theory, and a compensation voltage for unbalanced source voltage is calculated in based on a synchronous reference frame. By experiments, we show validity of proposed compensation method.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.1
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• pp.70-77
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• 2005

A new converter to transfer energy from a low-voltage AC current source to a battery is proposed. It is focused to find operational modes of the converter. The low-voltage AC current source is an equivalent of the piezoelectric generator, which converts the mechanical energy to the electric energy. The converter consists of a full-bridge MOSFET rectifier and a MOSFET boost converter in order to make the converter small and efficient. The operational principle and modes of the converter are investigated with the consideration of effects of the parasitic capacitances of MOSFETs and diode. The results are proved with simulation studies using PSIM and Pspice.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.2
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• pp.162-172
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• 1991

In proportion to the capacity enlargement of the induction motor system controlled by current source inverter, the capacitance of the commutating capacitor is enlarged and then the spike value of output voltage is increased at the moment of charge and discharge. Moreover, the output currnet includes a number of harmonic components. Such voltage spike and harmonics generate the torque ripple and lead to bad effects on the performance of the induction motor. In this study, all the harmonics excluding 17th and 19th harmonics were mostly elimunated by adopting 18-phase Triple High Frequency Current Source Inverter(HFCSI), and the spike component of output voltage was reduced by adding the Voltage Clamping Circuit(VCC). As a result, the torque ripple and the commutation loss were reduced and the performance of the system was improved. Experiments for speed control were carried out in the tripple current source inverter system for induction motor drive. Overall system was controlled by ONE CHIP MICROCOMPUTER(INTEL 8751). Control circuits were simplified and good experimental results in the constant V/F control were obtained due to the flexibility of the microcomputer.

• Journal of Power Electronics
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• v.2 no.4
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• pp.288-296
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• 2002

In this paper, a high frequency transformer - assisted auxiliary active resonant commutated snubber (HFTA-ARCS) for voltage source soft switching pulse width modulated power conversion circuits is presented. A three phase voltage source type soft switching inverter incorporating HFTA-ARCS circuits in its three bridge legs can reduce current rating of auxiliary active power switches and has sensorless simplified control scheme which any specified boost current management is not required for soft switching. Its operation principle and digital control scheme are described and a practical design method of circuit parameters on this HFTA-ARCS circuit is also introduced on the basis of computer simulation. Moreover, this space voltage vector modulated soft switching inverter system with DSP-based digital control scheme Is discussed and its effectiveness is proved on the basis of performance evaluations. The operating performances of this inverter system are also compared with those of conventional three-phase hard switching inverter under practical conditions of specified parameters.