• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.371-376
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• 2009

The Power Conditioning System is Power Transfer System which make array DC current to the Grid sinusoidal current. These are Low Frequency Transformer Inverter Type, High Frequency Transformer Inverter Type and Transformer-less Type. Low Frequency Transformer Type has a Excellent Isolation property, but doesn't have competitiveness in Size and Cost. Also High Frequency Transformer Type has a good Isolation property but there are many steps in Power transfer Switching. Nowadays, Transformer-less Type inverter change a transformer to DC/DC Converter which is small and cost effective. In this paper shown the DC/DC Converter Transformer-less Type multi-string inverter design and simulation. The Control Algorithm will be introduced and Simulation was accomplished.

• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.288-294
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• 2015

Recently, the module-integrated converter has shown an interest in the photovoltaic generation system. In this system, the high frequency transformer should be compact and efficient. The proposed method is based on the correlation characteristic between the copper and core loss to minimize the loss of transformer. By sizing an effective cross-sectional area and window area of core, the amount of loss is minimized. This paper presents the design and analysis of high frequency transformer by using the 3D finite element model coupled with DC-DC converter circuit for more accurate analysis by considering the nonlinear voltage and current waveforms in converter circuit. The current waveform in each winding is realized by using the ideal DC voltage source and switching component. And, the thermal analysis is performed to satisfy the electrical and thermal design criteria.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.90-94
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• 2000

A conventional power supply to drive a microwave oven has ferro-resonant transformer and high voltage capacitor(HVC). Though it is simple transformer is bulky heavy and has low-efficiency. To improve this defect a high frequency switching inverter-type power supply has been investigated an developed. in recent years. But because of it's additional circuit and devices inverter-type power supply is more expensive than conventional one. In this paper The design procedure of a novel HVC embedded high frequency transformer is proposed for down-sizing and cost reduction. Also transformer equivalent circuit model is derived by FEM analysis and parameter measurements. And the operation of proposed HVC embedded transformer is verified by simulation and experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05c
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• pp.15-17
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• 2002

Leakage inductance and temperature rise are two of the more impotent problems facing the magnetic core technology of today's high frequency transformers. Excessive leakage inductance increases the stress on the switching transistors and limits the duty-cycle, and excessive temperature rise can lead the design limitation of high frequency transformer with high current. The flat transformer technology provides a very good solution to the problems of leakage inductance and thermal management for high frequency power. The critical magnetic components and windings are optimized and packaged within a completely assembled module. The turns ratio in a flat transformer is determined as the product of the number of elements or modules times the number of primary turns. The leakage inductance increase proportionately to the number of elements, but since it is reduced as the square of the turns, the net reduction can be very significant. The flat transformer modules use cores which have no gap. This eliminates fringing fluxes and stray flux outside of the core. The secondary windings are formed of flat metal and are bonded to the inside surface of the core. The secondary winding thus surrounds the primary winding, so nearly all of the flux is captured.

• Journal of the Korean Society of Industry Convergence
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• v.5 no.3
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• pp.179-186
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• 2002

This paper proposed LC resonant current fed high frequency inverter for high frequency induction heating using leakage inductance of transformer and, its described operating principle. The analysis of circuit presented by using normalized parameter in considering leakage inductance of transformer and, discussed characteristic evaluation of inverter circuit in detail. The proposed inverter is operating ZVS to reduce turn-on and turn-off loss of switching devices so, raised an efficiency. And, the experimental apparatus was made on base characteristic evaluation of theoretical analysis to discuss possibility on high frequency source and confirmed a rightfulness theoretical analysis. A result of study, the proposed inverter is higher utilizing factor using on leakage inductance of transformer and show possibility, which is application on high frequency power system.

• Journal of Electrical Engineering and Technology
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• v.9 no.1
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• pp.154-161
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• 2014

To study and locate partial discharge(PD) and analyze the transient state of power transformer, there is a need for a high frequency model of transformer winding and calculation of its parameters. Due to the high frequency nature of partial discharge phenomenon, there is a need for an accurate model for this frequency range. To attain this goal, a Multi-Conductor Transmission Line (MTL) model is used in this paper for modeling this transformer winding. In order that the MTL model can properly simulate the transformer behavior within a frequency range it is required that its parameters be accurately calculated. In this paper, all the basic parameters of this model are calculated by the use of Finite Element Method (FEM) for a 20kV winding of a distribution transformer. The comparison of the results obtained from this model with the obtained shape of the waves by the application of PD pulse to the winding in laboratory environment shows the validity and accuracy of this model.

• Journal of Electrical Engineering and Technology
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• v.11 no.2
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• pp.383-392
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• 2016

This paper proposes the design considerations of resonant network and transformer magnetics for 500 kHz high switching frequency LLC resonant converter. The high power density can be effectively achieved by adopting high switching frequency which allows small size passive components in the converter. The design methodology of magnetizing inductance is derived for zero voltage switching (ZVS) condition, and the design methodology of the transformer and output capacitance is derived to achieve high power density at high operating frequency. Moreover, the structure of transformer is analyzed to obtain the proper inductance value for high switching operation. To verify the proposed design methodology, simulation and experimental results will be presented including temperature of passive and active components, and power conversion efficiency to evaluate dominant power loss. In addition, the validity of magnetics design will be evaluated with operating waveforms of the prototype converter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.4
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• pp.29-35
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• 2014

The purpose of high frequency transformer in the inverter is to reduce the voltage and current stresses of switch components when it operates at the large conversion ratio. But the loss of transformer is the major contributor in the efficiency of inverter. This paper presents the method of core design to minimize the loss of transformer. The total loss of transformer is minimized by adjusting the effective cross-sectional areas of core. The component ratio of losses are compared by using the finite-element analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.587-590
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• 2003

The first attention in designing a transformer for low temperature rise should be to reduce losses. Leakage inductance and temperature rise are two of the more impotent problems facing the magnetic core technology of today's high frequency transformers. Excessive leakage inductance increases the stress on the switching transistors and limits the duty-cycle, and excessive temperature rise can lead the design limitation of high frequency transformer with high current. The flat transformer technology provides a very good solution to the problems of leakage inductance and thermal management for high frequency power. The critical magnetic components and windings are optimized and packaged within a completely assembled module. The turns ratio in a flat transformer is determined as the product of the number of elements or modules times the number of primary turns. The leakage inductance increase proportionately to the number of elements, but since it is reduced as the square of the turns, the net reduction can be very significant. The flat transformer modules use cores which have no gap. This eliminates fringing fluxes and stray flux outside of the core. The secondary windings are formed of flat metal and are bonded to the inside surface of the core. The secondary winding thus surrounds the primary winding, so nearly all of the flux is captured.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.293-296
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• 2001

A conventional power supply to drive a microwave oven has ferro-resonant transformer and high voltage capacitor(HVC). Though it is simple, transformer is bulky, heavy and has low-efficiency. To improve this defect, a high frequency inverter type power supply has been investigated and developed in recent years. But, because of additional control circuit and switching device, inverter-type power supply is more expensive than conventional one. In this study, The design procedure of a novel HVC embedded high frequency transformer is proposed for down-sizing and cost reduction of Inverter-type power supply. Also, equivalent circuit mode] is derived by FEM analysis and impedance measurements. And the operation of proposed HVC embedded transformer is verified by simulations and experimental results.