• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1604-1613
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• 2018

The paper presents the equivalent circuit of an induction machine (IM) model which includes fundamental stray load and iron losses. The corresponding equivalent resistances are introduced and modeled as variable with respect to the stator frequency and flux. Their computation does not require any tests apart from those imposed by international standards, nor does it involve IM constructional details. In addition, by the convenient positioning of these resistances within the proposed equivalent circuit, the order of the conventional IM model is preserved, thus restraining the inevitable increase of the computational complexity. In this way, a compromise is achieved between the complexity of the analyzed phenomena on the one hand and the model's practicability on the other. The proposed model has been experimentally verified using four IMs of different efficiency class and rotor cage material, all rated 1.5 kW. Besides enabling a quantitative insight into the impact of the stray load and iron losses on the operation of mains-supplied and vector-controlled IMs, the proposed model offers an opportunity to develop advanced vector control algorithms since vector control is based on the fundamental harmonic component of IM variables.

• Proceedings of the KIEE Conference
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• 1979.08a
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• pp.138-141
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• 1979

The purpose of this paper is to develop an efficient model for the analysis of a John's Chopper Circuit. In the John's Chopper Circuit analysis, the open branches are removed from the associated graph to formulate the modified incidence matrix. An algorithm for the generation of a modified proper tree and fundamental cut set matrix from a network graph is developed, which utilizes much less computer storage space and computation time compared to the classical methods.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1119-1122
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• 1992

This paper deals with a novel method of modeling and analyzing multilevel pulse width modulation(PWM) inverter/rectifier, which leads to extraction of equivalent circuit in fundamental frequency domain. By the technique, we can draw out the corresponding linear time invariant circuit even thuogh the actual circuit is switched. A static VAR compensator using five-level inverter is modeled and simulated for the verification of the modeling.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.6
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• pp.90-95
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• 1997

In designing a resonant circuit of the inverter which puts induction heating with high frequency to the load, an inductance L of the circuit, the coupling coefficient of a transformer transfering the output power to load, and the coupling coefficient of load circuit heating with coil affect to the output power of a resonant circuit, the circuit Q and the frequency. Those characteristics of the circuit are analyzed through Thevenan's equivalent circuit of the coupling coefficient type which is derived from the T-type equivalent circuit of a transformer. On this equivalent circuit, the impedance of a transformer referred to its primary side is not only proportional the square of turn ratio, nZ, but also the square of coupling coefficient, K2 This paper proposed a more accurate fundamental method to design a resonant circuit of the inverter by using the Thevenan's equivalent circuit.

• 전기의세계
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• v.22 no.3
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• pp.25-34
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• 1973

In this paper, the characteristics of a single phase induction motor which is considered the space harmonic flux by the double revolving field theory is analysed. As the rotor resistance for the fundamental flux is separated from the resistance for the rotor bar and end-ring, and the rotor leakage reactnace is separated from the skew leakage reactance and the other, so the circuit constants for the space harmonic flux is expressed by the circuit constants for the fundamentals. As the ratio of the circuit constants for the magnetizing reactance is used, the generalized equivalent circuit is made up. the characteristic equation which is able to analysis the subdivided characteristics by the above circuit is induced. The ratio of the circuit constants and the skew angle being changed, the variations of the torque-speed characteristics for the fundamentals and harmonics is examined by this equation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.6
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• pp.321-329
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• 2002

A protection scheme for series active compensator is presented and analyzed in this paper. The proposed series active compensator operated as a high impedance K($\Omega$) to the fundamentals when short-circuit faults occur in the power distribution system, and two control strategies are proposed in this paper The first is the method by detecting the fundamental source current through the p-q theory, the second is the method by detecting the fundamental component of load current in Synchronous Reference Frame(SRF). When the short-circuit faults occur in the power distribution system, the proposed scheme can protect the series active compensator without additional protection circuits. The validity of the Proposed Protection scheme was investigated through experimental results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.652-655
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• 2004

In gear-train design, power-flow analysis is a very important process. The method for power-flow analysis apply the power balance equation and torque balance equation to each fundamental circuit. Then, the equation are solved simultaneously to determine the power-flow in planetary gear train. In this paper we perform power-flow analysis of a 6-speed automatic transmission. With this results are used to represent block diagram. In addition, the efficiencies of epicyclic inversion of the 6-speed automatic transmission is obtained.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.543-547
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• 2001

A protection scheme for Unified Power Quality Conditioner (UPQC) is presented and analyzed in this paper. The proposed UPQC has the series active power filter operated as a high impedance k($\Omega$) to the fundamentals when short-circuit faults occur in the power distribution system, and three control strategies are proposed in this paper. The first is the method by detecting the fundamental source current through the p-q theory, the second is the method by detecting the fundamental component of load current in Synchronous Reference Frame(SRF) and the third is the method by detecting the input voltage. When the short-circuit fault occur in the power distribution system, the proposed scheme protects the UPQC without additional protection circuits. The validity of proposed protection scheme is investigated through simulation results.

• 전기의세계
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• v.21 no.1
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• pp.7-12
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• 1972

General steady state equivalent circuits are derived for the family of single phase motor having two windings with non-quadrature. First, the fundamental voltage equations of motor are derived by Faraday-Krichhoff's low in the fiew of the flux distribution in the modified motor with Kron primitive machine. Those equations are arranged in to f-b equations by transformation matrix. To using the above equations for circuit; 1) The concept of current-source was much help to sove the realtions between matrix impedance equation and circuit analysis 2) The simplification of the circuit to the mutual impedance matrix elements is easy to considerations of motor characteristics in the case of inserted external auxiliary winding impedance. Finally, this equivalent circuit showing as a single phase induction motor with quadrature winding is described by each conditions.

• The Transactions of the Korean Institute of Power Electronics
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• v.28 no.1
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• pp.76-81
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• 2023

A new test circuit for an MMC-based valve HVDC power converter is proposed. The proposed scheme satisfies the required clauses from IEC-62501. The valve test current contains second harmonic component and DC offset as well as a fundamental component that is quite similar to the real operating arm current of MMC based HVDC power system. The structure of the proposed test circuit is simple compared to conventional test circuits. Furthermore, the power supply voltage rating of the proposed test circuit is reduced dramatically around 20% of the conventional scheme with the same current rating. The validity of the proposed test circuit is verified through simulation and experimental results.