• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.1
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• pp.30-39
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• 2003

In SRM driving, the current rate is directly related to the rate of switching device and in cost reduction, the Parallel switching operation is the alternatives because it has the smaller current rate through current division. There ire many investigations for the parallel switching operations to equaling the current division. However it remains many problems for practical usage. The reason Is that the switching characteristics are mainly relied on the different saturation voltage of each device etc. and these factors are not altered by a circuit designer. In order to compensate this problem, a proper resistance is experimently inserted to the switching device. But this method can not be the optimal solution. Therefore this paper propose a new parallel operation of SRM which uses a parallel phase winding to remove the traditional effect of switching device such as saturation voltage according to the division of current. Also the reliable and stable driving is improved through experiments and the detailed principles.

• Proceedings of the KIEE Conference
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• 2003.04a
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• pp.66-68
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• 2003

In a motor drive, the current rating is directly related to the rating of a switching device, and the parallel switching operation for a cost reduction is the alternatives because it has the smaller current rating through current division. There are many investigations for the parallel switching operations to equaling the current division. However it remains many problems for practical usage. This paper proposes a new parallel operation which uses a parallel phase winding to remove the traditional effect of switching device such as saturation voltage according to the division of current. The proposed strategy is verified by theoretical and experimental verification.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.115-120
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• 2003

In a motor driving, the current rate is directly related to the rate of a switching device and in cost reduction, the parallel switching operation is the alternatives because it has the smaller current rate through current division. There are many investigations for the parallel switching operations to equaling the current division. However it remains many problems for practical usage. The reason is that the switching characteristics are mainly relied on the different saturation voltage of each device etc. and these factors are not altered by circuit designer. In order to compensate this problem, a proper resistance is experimently inserted to the switching device. But this method can not be the optimal solution. Therefore this paper proposes a new parallel operation which uses a parallel phase winding to remove the traditional effect of switching device such as saturation voltage according to the division of current. Also the reliable and stable driving is improved through experiments and the detailed principles.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.24-28
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• 2002

In a motor driving, the current rate is directly related to the rate of a switching device and in cost reduction, the parallel switching operation is the alternatives because it has the smaller current rate through current division. There are many investigations for the parallel switching operations to equaling the current division. However it remains many problems for practical usage. The reason is that the switching characteristics are mainly relied on the different saturation voltage of each device etc. and these factors are not altered by a circuit designer. In order to compensate this problem, a proper resistance is experimently inserted to the switching device. But this method can not be the optimal solution. Therefore this paper proposes a new parallel operation which uses a parallel phase winding to remove the traditional effect of switching device such as saturation voltage according to the division of current. Also the reliable and stable driving is improved through experiments and the detailed principles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.141-148
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• 2002

In a motor driving, the current rate is directly related to the rate of a switching device and in cost reduction, the parallel switching operation is the alternatives because it has the smaller current rate through current division. There are many investigations for the parallel switching operations to equaling the current division. However it remains many problems for practical usage. The reason is that the switching characteristics are mainly relied on the different saturation voltage of each device etc. and these factors are not altered by circuit designer. In order to compensate this problem, a proper resistance is experimently inserted to the switching device. But this method can not be the optimal solution. Therefore this paper proposes a new parallel operation which uses a parallel phase winding to remove the traditional effect of switching device such as saturation voltage according to the division of current. Also the reliable and stable driving is improved through experiments and the detailed principles.

• Journal of Power Electronics
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• v.11 no.1
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• pp.16-20
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• 2011

This paper presents a zero-voltage-switching (ZVS) boost converter using a coupled inductor. It utilizes an additional winding to the boost inductor and an auxiliary diode. The ZVS characteristic of the proposed converter reduces the switching losses of the active power switches and raises the power conversion efficiency. The principle of operation and a system analysis are presented. The theoretical analysis and performance of the proposed converter were verified with a 100W experimental prototype operating at a 107 kHz switching frequency.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.5
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• pp.502-507
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• 2004

The forward planar transformer, which had power capacity of 300 W, input voltage of 220 V, output voltage of 15 V, and switching frequency of 300 KHz, was designed and manufactured by using the planar core with large effective area and the flat copper leadframes for miniaturization and high efficiency of the switching mode power supply (SMPS). As well as, a forward converter equipped with the above mentioned planar transformer was manufactured and electromagnetic characteristics were investigated. The numerical value of turns for 1st and 2nd winding were 15 and 2 respectively The self inductance of 1st winding was 1.592 mH, very low leakage inductance of 2.7 $\mu$H, and the coupling factor of 0.928 were obtained at switching frequency of 300 KHz. The high efficiency of 88.62 % for the SMPS equipped with planar transformer was obtained at power capacity of 300 W.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.43 no.7
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• pp.1050-1060
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• 1994

This paper is a study on the computer simulation of the characteristics of the superconducting fault current limiter. Input variable parameters are apparent power, load resistance value, line resistance value and so on. Initial fault current 2 times larger than the trigger current is required to reduce the switching time of SFCL. The propagation velocity increases abruptly, the transport current is several times larger than the ciritical current. In this paper, the switching time is calculated to be 323$\mu$ sec, and the initial fault current is 19 times larger than the critical current. Because the trigger coils are bifilar winding, they have little impedance in superconducting state. After fault occurred, the limiting coil acts as a superconducting reactor and the trigger coils quench at a critical current. Without the SFCL in the circuit, fault current after the load impedence is shorted might be increased to 1100A. The fault current is, therefore, successfully limited by the superconducting limiting coil to 100A determined by the coil inductance.

• Journal of Magnetics
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• v.18 no.3
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• pp.361-364
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• 2013

Permanent magnet flux switching motor (PMFSM) is a novel double salient machine which employs PMs instead of field winding for excitation. PMFSM contains only one set of armature winding, thereby features simple control strategy, low cost power inverter and substantial high efficiency. Due to the unique double salient structure and operation principle, the generated cogging torque in PMFSM is critical and quite different compared to the traditional PM machines. This paper presents and investigates various design techniques for reducing cogging torque in PMFSM. Firstly, an analytical model is proposed to study the influence of different methods on cogging torque. Then the optimal design parameters for minimizing cogging torque are determined by the analytical model, which significantly reduces the computational efforts. At last, the cogging torque with different design approaches are simulated by FEA along with the average output electromagnetic torque, which validates the analysis above.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.379-381
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• 2008

Generally additional leakage inductance and two clamp diodes are adopted into the conventional phase shift full bridge (PSFB) converter for reducing the voltage stress of secondary rectifier diodes and extending the range of zero voltage switching (ZVS) operation. However, since additional leakage inductance carries the ac current similar to the primary one, the core and copper loss oriented from additional leakage inductance can be high enough to decrease the whole efficiency of DC/DC converter. Therefore, in this paper, a new ZVS phase shift full bridge converter with separated primary winding (SPW) is proposed. Proposed converter makes the transformer and additional leakage inductor with one ferrite core. Using this method, leakage inductance is controlled by the winding ratio of separated primary winding. Moreover, by manufacturing the both magnetic components with one core, size and core loss can be reduced and it turns out the improvement of efficiency and power density of DC/DC converter. The operational principle of proposed converter is analyzed and verified by the 1.2kW prototype.