• Journal of Electrical Engineering and Technology
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• v.2 no.1
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• pp.89-97
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• 2007

This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed half-bridge high frequency PWM inverter with a high frequency planar transformer link in addition to input DC busline side power semiconductor switching devices for PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC buslines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, a high switching frequency IGBTs can be actually selected in the frequency range of 60 kHz under the principle of soft switching. The performance evaluations of the experimental setup are illustrated practically. The effectiveness of this new converter topology is proved for such low voltage and large current DC-DC power supplies as DC bus feeding from a practical point of view.

• Proceedings of the KSR Conference
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• 2008.06a
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• pp.499-504
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• 2008

DC substation of urban transit supplies a suitable DC power on electricity vehicles by being supplied from KEPCO. DC substation is verified electrical safety of system through pre-operation inspection on electrical installations to be supplied power from KEPCO. However, because test items and method for DC traction system are unprepared on pre-operation inspection, the general safety and performance verification of DC traction system are very insufficient. Therefore this paper analyze the overseas test examples such as factory equipment tests, factory combined tests and railway tests for the safety and performance verification of DC traction system and present a suitable test items and test standard in domestic.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.6
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• pp.569-575
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• 2003

This paper present a new fully-automated PC-based instrumental system that could quickly measure and analyze the efficiency of switching power supplies for the entire operating range. In the proposed system, we applied an Indirect method for high-voltage low-current measurements and a direct method for low-voltage high-current measurements, in order to obtain a high accuracy with minimum equipment requirement. Compared to the conventional methods, the newly proposed system offers more accurate and much faster real-time assessment of the efficiency with minimum measurement error. The performance and accuracy of the proposed system are verified using a 50 W switching power supply intended for telecommunication applications.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.3
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• pp.233-239
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• 2014

This paper proposes that each converter supplies the power using the proposed droop control for the parallel operation of the converters. The proposed method is easy to increase the power as parallel system in DC distribution. By improving conventional droop-control method used in AC grid newly, a droop controller is designed to apply droop control in DC grid. And the control method of the proposed droop controller is explained particularly. In this paper, by applying the proposed control method to DC distribution system, propriety is verified through the simulation and the experiment.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.281-283
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• 2006

This paper presents two new circuit topologies of DC bus lineside active edge resonant snubber assisted soft-switching PWM full-bridge DC-DC converter acceptable for either utility AC 200V-rms or AC 400V-rms input voltage source. All the active power switches in the full-bridge arms and DC busline can achieve ZCS turn-on and ZVS turn-off commutations and the total turn-off switching power losses of all active switches can be reduced for high-frequency switching action. The effectiveness of these new DC-DC converters topologies is proved for low voltage and large current high efficiency DC-DC power supplies as TIG arc welding machine from a practical point of view.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1389-1399
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• 2013

A discrete controller is designed for low power dc-dc switched mode power supplies. The approach is based on time domain and the control loop continuously and concurrently tunes the compensator parameters to meet the converter specifications. A digital state feedback control combined with the load estimator provides a complete compensation, which further improves the dynamic performance of the closed loop system. Simulation of digitally controlled Buck converter is performed with MATLAB/Simulink. Experimental results are given to demonstrate the effectiveness of the controller using LabVIEW with a data acquisition card (model DAQ Pad - 6009).

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.747-751
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• 2004

In recent years power supplies for telecommunication equipment is required smaller size and higher efficiency, and low noise operation. There exists a series resonant converter in which the switching loss is reduced in order to realize a high efficiency converter. However, if a constant voltage regulation is required. The switching frequency varies widely. In this paper we study the details of resonant DC-DC converter in which the realize a high efficiency converter.

• Journal of Power Electronics
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• v.4 no.1
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• pp.56-63
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• 2004

A new driving circuit for the SPSS (Single-Pulse Soft-Switching) PFC converter is proposed. The switching device of a SPSS converter switches once in every half cycle of an AC commercial power source. Therefore, it can be solved many problems caused by the high frequency operation. The proposed SPSS converter achieves the soft-switching operation and the EMI noise can be reduced. The resonant capacitor voltage supplies to the resonant inductor even if the input AC voltage is the vicinity of zero cross voltage. Then, the power factor and input current waveform can be improved without delay time. A new driving circuit achieves the operation of SPSS converter by one switching drive circuit. The proposed converter can be satisfied the IEC standard sufficiently

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.5
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• pp.351-357
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• 2004

In this paper, we present an analytical method that provides fast and efficient evaluation of the conversion efficiency for switching power supplies. In the proposed method, the conduction losses are evaluated by calculating the effective values of the ideal current waveform first and incorporating them into an exact equivalent circuit model of the switching power supply that includes all the parasitic resistances of the circuit components. While the winding losses and core losses are accurately accounted for the magnetic components, the skin and proximity effects are assumed to be negligible in order to simplify the analysis. The validity and accuracy of the proposed method are verified with experiments on a prototype active-clamped forward converter with synchronous rectification. An excellent correlation between the experiments and theories are obtained for the input voltages of 36-75 V with 4-6 MOSFETs employed for the synchronous rectification.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.676-681
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• 2005

The regenerative braked cars are being introduced in DC electric railway for energy saving. There has been a recent tendency for DC traction substation with regenerative inverter to increase in number. This is strongly related to the desire for effective utilization of electric power regenerated by DC electric cars and to the aim ensuring stable operation of regenerative braking system. The regenerative inverters DC power feed back from a generative car into AC power at a substation and supplies it to distribution lines. This paper suggest the result of characteristic analysis and capacity simulation. economical analysis in the regenerative inverter system.