• Clean Technology
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• v.21 no.1
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• pp.45-52
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• 2015

We have introduced switching poles in the conventional electrolysis for the removal of ammonia in aquaculture wastewater to prevent the fouling on the electrode surface by the deposition of insoluble metallic compounds. We have also tried to locate the optimal period of switching poles considering the effect of the current loss during switching poles on the free chlorine generation. First, we have observed the decrease of free chlorine generation with the decrease of the period of switching poles due to the expected current loss, and this would lead to the decrease of ammonia removal efficiency. Meanwhile, the measurement of calcium and magnesium concentration in wastewater vs. the period of switching poles have demonstrated that a properly low level of fouling on the electrode surface could be retained with a period of switching poles of less than 60 sec by the decomposition of metallic compounds during switching poles. In a summary, we have optimized the period of switching poles to gain a high level of free chlorine generation and a high level of fouling prevention on the electrode at the same time.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.971-976
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• 2011

This paper proposes a test system for a valve and poles building blocks used for large scale inverters such as STATCOM, SSSC, UPFC and VSC HVDC. Power semiconductors in the valve are normally connected in series to withstand switching voltage much larger than the voltage rating of a single power semiconductor. Therefore, there is a need to verify if the dynamic voltage sharing during switching in a valve is satisfactory. In this paper, we propose a test system that provides the necessary test condition: voltage and current in the valve using resonant circuits. A test scheme for a single phase inverter consisting two poles is also proposed. The performance of the inverter pole has to be verified at the factory test, before the system is installed at the site to secure the reliability of the system. The proposed scheme makes it possible to confirm if the pole can withstand voltage and current switching condition and handle loss.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.12
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• pp.664-669
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• 2002

In this paper the method to determine tire optimal switching instants in order to reduce the transient surges during switching not relevant to the neutral treatment of shunt reactors is presented. This method consists of the following two steps. First, the instants of the voltage peaks between the contacts of each poles and the voltage magnitude as well as the moments of the current zero crosses were found out analytically. Next, the instants of the contact touches or separations were determined in consideration of the rate of decrease of dielectric strength or a circuit breaker and the variation of the its operating time. The results obtained from the EMTP(Electromagnetic Transient Program) analysis studies show that the making instants are established at the peak voltage of each three poles for any conditions of a neutral point and the possible upper limited values of inrush currents due to the variation of the mechanical operating time can be estimated.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.151-154
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• 1999

This paper presents a driving method of 3-phase 4-poles SRM(switched reluctance motor) drived by switching angle control. In this study, the switching angle is determined from approximated analysis and computer simulation by using MATLAB for high efficiency according to the speed and torque required by load, and then microcontroller controls the switching angle of asymmetrical inverter in SRM driver. Also, we experiment the maximum forque driving and maximum power driving by controlling switching angle available to electric vehicle.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.725-728
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• 2000

This paper presents the switching angle and voltage for maximizing torque of 4-phase 6-poles SRM. The switching angle and voltages was determined through the approximated analysis and computer simulation by using SIMULINK according to the speed and torque required by load but we used new analytic equation from maximum torque characteristic And then one-chp micro-controller controls the switching angle and voltage of an asymmetrical inverter in the SRM driver. Also we expects that this method reduce micro-controller load and realize approximated real time control

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.74-76
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• 2005

The SRG(Switched Reluctance Generator) consists of simple stator and rotor. The advantage of SRG is very endurance and low cost. Because of SRG have no magnetic, So we should obtain current of magnetic to stator. But in this step SRG have disadvantage. Disadvantage of SRG is more torque ripple, vibration and noise than other machines. This paper shows the simulation of SRG with 3phases, 6 stator poles and 4 rotor poles. We intpret the characteristics of SRG's constant voltage and torque ripple according to change switching angle.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.7
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• pp.706-717
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• 1991

In order to remove the assumption of full state availability which is one of the major difficulties with the practical realization of variable structure control systems,a new switching function with a dynamic structure is proposed. And the control performances of the output feedback variable structure control systems with the dynamic switching function are evaluated through simulation studies. The proposed dynamic switching function is driven by small number of measured output and input variables while conventional static switching function requires full state information. Therefore, the proposition of the dynamic swiching function makes practical implementation of output feedback variable structure control scheme possible for the systems with unmeasurable state variables, high order systems and large scale systems that the conventional variable structure control schemes with static switching function cannot be applied. In the variable structure control systems with the dynamic switching function, desired control performance can be guaranteed by proper choice of design parameters such as poles of switching function dynamic equation and switching control gains even though small number of measured output and input variables are provided as shown in simulation resuls.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.92-97
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• 2014

The SRM is a doubly salient, singly excited machine. The torque is developed by the tendency for the magnetic circuit to adopt a configuration of minimum reluctance, i.e. for the rotor to move into in line with the stator poles and to maximize the inductance of the coils excited. It is common practice to combine them into groups of poles which are excited simultaneously; for example, 8/6 SRM (8 stator poles and 6 rotor poles) for 4 phases, 6/4, 12/8 SRM for 3 phases, 4/2, 6/3 SRM for 2 phases. Small number of phases in two-phase SRMs allows more cost savings with regards to the switching devices in the converter. The stator back irons of two phase 6/3 SRM and C-core 4/3 SRM does not experience any flux reversal as the flux is in the same direction whether phase A or B is excited. In this study, the similarities, the differences, and structural characteristics between the two SRMs was studied, The magnetic analysis also has been carried out by the finite element method analysis (FEM).

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.70-73
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• 2002

High frequency digital LSI circuits are usually composed of many sub-circuits coupled with interconnects. They sometimes causes serious problems of the fault switching by time-delays, crosstalks, reflections of signals and so on. Therefore, it is very important to develop a user-friendly simulator for solving these problems. Although a moment matching method is widely used as the reduction technique of interconnects, it may happen to arise erroneous results for evaluating the poles far from the origin. In this paper, we show an asymptotic method in the complex frequency-domain, where we calculate the exact poles and residues giving large effect to the transient responses. Then, the interconnects are replaced by the asymptotic equivalent circuits using the poles and residues. Thus, we can develop a users-friendly simulator using the equivalent circuits.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.3
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• pp.269-274
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• 2013

Fault-tolerant capability, wide speed range and overload capability are required in electric motors used in electric vehicles. In this paper, based on the analysis of the all poles wound and alternate poles wound flux-switching permanent-magnet machines, an optimization method is studied to reduce torque ripple. The method takes account of both flux-leakage and cogging torque. The simulation result shows that the method can reduce the torque ripple effectively. This study lays the foundation for the further application of FSPM in electric vehicles.