• Journal of Electrical Engineering and information Science
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• v.3 no.3
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• pp.366-372
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• 1998

A high efficiency interleaved active clamp forward converter with self driven synchronous rectifiers for a modular power processor is presented. To simplify the gate drive circuits, N-P MOSFETs coupled active clamp method is used. An efficiency about 90% for the load range of 50-100% is achieved. The details of design for the power stage and current mode control circuit are provided, and also some experimental results are given.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.582-584
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• 1996

A new single stage AC/DC converter with a high power factor is proposed. The proposed converter gives good power factor correction, low current harmonic distortions, and tight output regulations. This converter also has an high efficiency by employing Active-clamp method and synchronous rectifiers. To verify performances of the proposed converter, 90W-converter is designed. This prototype meets the IEC555-2 requirements satisfactorily with nearly unity power factor.

• Journal of Electrical Engineering and information Science
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• v.2 no.3
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• pp.123-131
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• 1997

Design of single stage AC/DC converter with high power factor for low power level applications is proposed. The proposed converter gives the good power factor correction, low line current harmonic distortions, and tight output voltage regulations. This converter also has a high efficiency by employing an active clamp method and synchronous rectifiers. To verify the performances of the proposed converter, a 90W-converter has been designed. The modelling of this proposed converter is power formed using an averaging technique and based on this model a detailed analysis is carried out. This prototype meets the IEC555-2 requirements satisfactorily with nearly unity power factor and high efficiency.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.1
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• pp.70-75
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• 2014

TMR(triple modular redundant) digital excitation system with simulator is developed for tuning optimal control parameters during commissioning test and coping with system faults rapidly. A new system which mocks up virtual generator, turbine, grid can simulate as if excitation system is connected to a real generator system by setting four switches. The maintenance crew using the simulator is able to test perfectly the phase controller rectifiers, field breaker, sequence relays as well as TMR controller of the excitation system. Commissioning and performance results about the excitation system with simulator is discussed. The trial product was installed and operated at a 500MW thermal power plant after the commissioning test.

• Journal of Power Electronics
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• v.15 no.1
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• pp.190-201
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• 2015

This paper uses the switching function approach to present a simple state model of the Vienna-type rectifier. The approach introduces the relationship between the DC-link neutral point voltage and the AC side phase currents. A novel direct power control (DPC) strategy, which is based on the sliding mode control (SMC) for Vienna I rectifiers, is developed using the proposed power model in the stationary ${\alpha}-{\beta}$ reference frames. The SMC-based DPC methodology directly regulates instantaneous active and reactive powers without transforming to a synchronous rotating coordinate reference frame or a tracking phase angle of grid voltage. Moreover, the required rectifier control voltages are directly calculated by utilizing the non-linear SMC scheme. Theoretically, active and reactive power flows are controlled without ripple or cross coupling. Furthermore, the fixed-switching frequency is obtained by employing the simplified space vector modulation (SVM). SVM solves the complicated designing problem of the AC harmonic filter. The simplified SVM is based on the simplification of the space vector diagram of a three-level converter into that of a two-level converter. The dwelling time calculation and switching sequence selection are easily implemented like those in the conventional two-level rectifier. Replacing the current control loops with power control loops simplifies the system design and enhances the transient performance. The simulation models in MATLAB/Simulink and the digital signal processor-controlled 1.5 kW Vienna-type rectifier are used to verify the fast responses and robustness of the proposed control scheme.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.2
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• pp.131-137
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• 2013

In this paper, the phase-shift full-bridge DC/DC converter with fixed-phase operation inverter is proposed. The proposed circuit consists of two full-bridge inverters which are connected in parallel. While one full-bridge inverter operates as the fixed-phase, it regulates the output voltage by adjusting the phase of the other inverter. During the normal operation period, the proposed circuit makes the less amount of conduction loss of the primary switches and secondary synchronous rectifiers, as well as the less amount of the current ripple of the output inductor, than the conventional phase-shift full-bridge DC/DC converter does. Also, it achieves high efficiency by reducing the snubber loss of the secondary synchronous rectifier. To sum up, the present inquiry analyzes the theoretical characteristics of the proposed circuit, and shows the experimental results from a prototype for 450W power supply.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.16-21
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• 2005

In paper, propose new partial resonance ZCS PWM controlled High frequency insulating Full-bridge DC/DC converter not using exciting current of high frequency transformer. It is compared with the existing principles in characteristics. It also realizes a widely stabilized ZVS operating using new ON-OFF control method at synchronized power rectification MOSFET of high frequency insulating transformer secondary. Besides, it is brought over 97[%] measurement efficiency by proposed DC-DC converts. It is proved effectiveness of new methods using DC UPS PWM rectifier as switching power supply.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.2
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• pp.64-72
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• 2001

In this paper, forward Zero Voltage Switching Multi Resonant Converter(ZVS MRC) for non-contact charging energy transmission is reposed. The forward ZVS MRC is effective in adsorbing parasitic element as well as minimizing the switching loss. That can accommodate very high frequency. So forward ZVC MRC is applied to non-contact charging energy transmission. Used converter has saperatable transformer and synchronous rectifiers. Coupling coefficient(k), leakage inductance, coupling inductance and resonant frequency are observed for the air gap. By using the observed value, this circuit is designed and implemented. This proposed circuit is simulated by the PSPICE and experimented. The voltage stress of a main switch and the output power of the converter are measured. This paper show that is compatible for non-contact charging energy transmission.