• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.96-98
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• 2008

This paper present in-wheel BLDC motor using parallel winding. The voltage of proposed motor is higher than Y-connection three phase BLDC motor in order to separated connection. When the stator resistance and inductance are stable, maximum phase current and maximum torque is increased by high injected voltage. The proposed motor is verified from experimental result of the 2[kW] in-wheel motor on electric vehicle drive.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.9
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• pp.1536-1545
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• 2008

In this paper, we research a new method for efficiency improvement of a single-phase Induction motor by minimization of the stator loss. To make this, we perform winding design which is based on balanced and quasi-balanced operation condition. It gives efficiency improvement greatly but poor starting torque simultaneously. To obtain the best efficiency improvement maintaining the maximum and starting torque, the optimal winding specification and rotor dimension is determined with variation of secondary resistance, running capacitor and turn ratio. Finally, this paper gives the comparison between the simulation results and experimental results.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.452-454
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• 1999

In this paper, sample coils for stator form-wound winding of traction motor were made for the accelerative thermal degradation composed of heat, vibration, moisture and overvoltage. In progress of test periods, diagnosis tests such as insulation resistance, dielectric loss and partial discharge were investigated. Reliability and expected life were evaluated on the insulation system for 200 class traction motor considering various environmental stress.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.1
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• pp.93-101
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• 2002

In this study, the stator form-winding sample coils based on silicone resin and polyimide were made for fault prediction and reliability estimation on the C-Class(200$\^{C}$ ) insulation system of traction motors. The complex accelerative degradation was periodically performed during 10 cycles, which was composed of thermal stress, fast rising surge voltage, vibration, water immersion and overvoltage applying. After aging of 10 cycles, the condition diagnosis test such as insulation resistance '||'&'||' polarization index, capacitance '||'&'||' dielectric loss and partial discharge properties were investigated in the temperature range of 20 ∼ 160$\^{C}$. Relationship among condition diagnosis tests was analyzed to find a dominative degradation factor and an insulation state at end-life point.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2118-2122
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• 2005

This test was performed to assess the corelation of insulation deterioration condition with breakdown voltage of the stator winding of 3.3kV class induction motors which have been in service for 10 years after being installed in 1993. The insulation diagnostic tests include resistance, polarization index(P.I), dissipation factor$({\Delta}tan{\delta})$, maximum partial discharges (Qmax) and AC breakdown test. we evaluated the corelation of insulation diagnostic test with AC breakdown test for stator wilding of high voltage induction motor.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.1
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• pp.52-56
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• 2011

The ongoing Superconducting Fault Current Limiter(SFCL) development mainly has focused on the application of commercializaton and power system through combining with normal-conducting device, moving away from current-limiting method, which is solely dependant on the existing superconductor. Compared to the structural development above, on the other hand, the research on applying superconducting current-limiting element to SFCL, the heart of SFCL, still has a lot left to do, apart form traditional resistive type SFCL. In this study, we looked into the current limiting characteristic of SFCL using core and coil. YBCO coated conductor with stainless steel stabilizer layer was verified by the excellent of current-limiting element of the resistive type SFCL that has a high Jc and index as well as being superior in mechanical property. Also, we study temperature characteristics and resistance characteristics, max voltage, response time and current-limiting ability that can be an indicator as current-limiting element while applying to superconducting current-limiting element caused by variation of winding direction, winding ratio of SFCL using core and coil.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.12-14
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• 2004

We investigated current limiting characteristics of the flux-lock type high-Tc superconcting fault current limiter(HTSC-FCL) according to fault angles. The Flux-lock type HTSC-FCL consists of primary and the secondary copper coils that are wound in parallel each other through the iron core and YBCO thin flim. In this paper, the current limiting characteristics of the flux-lock type HTSC-FCL according to fault angles in case of the subtractive and additive polarity windings were compared and analyzed. From the results, the flux-lock type HTSC-FCL could limit more quickly fault current as the fault angles increased irrespective of the fault angles. On the other hand, the initial power burden of HTSC element after a fault happened increased as the fault angles increased. In addition, it was confirmed that the resistance of flux-lock type HTSC-FCL in case of subtractive polarity winding was more increased than that of additive polarity winding and that the peak current of fault current in case of subtractive polarity winding was larger than that of the additive polarity winding case.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.358-363
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• 2010

This paper proposes a step-by-step method of determining the parameters of equivalent circuit which is considered the no load losses for the single phase induction motor which has the starting winding. This method is comprised of three steps, and the stator resistance which is measured by the method of voltage drop is treated as constant and the stator and the rotor leakage reactances are assumed to be the same in every step. The test results of no load and locked rotor test are used in the 1st and 2nd step, and the ratings of name plate of the motor are needed in the 3rd step. In the 1st step, the traditional equivalent circuit parameters are directly calculated by no load and locked rotor conditions. In the next step, five nonlinear simultaneous equations for five unknown parameters can be set up by no load and locked rotor equivalent circuits. These equations are solved by using the initial parameters obtained by the 1st step parameters. In the final step, three nonlinear simultaneous equations for rotor winding resistance, leakage reactance and no load losses component resistance can be set up by equivalent circuit under the rated operation. Three parameters are solved by using the 2nd step parameters. Thus, equivalent circuit parameters are gradually refined step by step. The validity of the proposed method is evaluated by comparing the computed values obtained by the equivalent circuit parameters with the experimental values of the load test.

• Progress in Superconductivity and Cryogenics
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• v.20 no.4
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• pp.26-30
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• 2018

The turn-to-turn contact resistance of 2G high temperature superconducting (HTS) coils with metal insulation (MI) is closely related to the stability of the coils, current charging rate and delay time [1]. MI coils were fabricated using five kinds of metal tapes such as aluminum (Al) tape, brass tape, stainless steel (SS) tape, copper (Cu)-plated tape and one-sided Cu-plated SS tape. The turn-to-turn contact surface resistances of co-winding model coils using Al tape, brass tape, and SS tape were 342.6, 343.6 and $724.8{\mu}{\Omega}{\cdot}cm^2$, respectively. The turn-to-turn contact resistance of the model coil using the one-sided Cu-plated SS tape was $ 248.8{\mu}{\Omega}{\cdot}cm^2$, which was lower than that of Al and brass tape. Al or brass tape can be used to reduce contact resistance and improve the stability of the coil. Considering strength, SS tape is recommended. For strength and low contact resistance, SS tape with copper plating on one side can be used.

• Transactions on Electrical and Electronic Materials
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• v.9 no.6
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• pp.255-259
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• 2008

The magnetic field application effect on resistance of a high-$T_c$ superconducting (HTSC) element comprising a flux-lock type superconducting fault current limiter (SFCL) was investigated. The YBCO thin film, which was etched into a meander line using a lithography, was used as a current limiting element of the flux-lock type SFCL. To increase the magnetic field applied into HTSC element, the capacitor was connected in series with a solenoid-type magnetic field coil installed in the third winding of the flux-lock type SFCL. There was no magnetic field application effect on the resistance of HTSC element despite the application of larger magnetic field into the HTSC element when a fault happened. The resistance of HTSC element, on the contrary, started to decrease at the point of four periods from a fault instant although the amplitude of the applied magnetic field increased.