• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.81-86
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• 2011

In this paper, fractal microstrip patch antenna in a semicircle, by designing a multi-resonant antenna was improved by bandwidth issues, including the IEEE 802.11 wireless LAN and IEEE802.16e-band mobile WiMax specification both of which can contain non-directional antenna design and measured characteristics of the antenna for multi-resonant resonant frequency, impedance matching, radiation pattern, brilliantly polarity and multiple independent frequencies that can be controlled to meet the three semicircular wireless communications by inserting fractal patch antenna was designed.

• Journal of Power Electronics
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• v.7 no.3
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• pp.246-256
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• 2007

In this paper, a novel type auxiliary active edge resonant snubber assisted zero current soft switching pulse modulation Single-Ended Push Pull (SEPP) series load resonant inverter using IGBT power modules is proposed for cost effective consumer high-frequency induction heating (IH) appliances. Its operating principle in steady state is described by using each switching mode's equivalent operating circuits. The new multi resonant high-frequency inverter with series load resonance and edge resonance can regulate its high frequency output power under a condition of a constant frequency zero current soft switching (ZCS) commutation principle on the basis of the asymmetrical pulse width modulation (PWM) control scheme. Brand-new consumer IH products using the proposed ZCS-PWM series load resonant SEPP high-frequency inverter using IGBTs is evaluated and discussed as compared with conventional high-frequency inverters on the basis of experimental results. In order to extend ZCS operation ranges under a low power setting PWM as well as to improve efficiency, the high frequency pulse density modulation (PDM) strategy is demonstrated for high frequency multi-resonant inverters. Its practical effectiveness is substantially proved from an application point of view.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.151-152
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• 2011

This paper describes a cross-regulation characteristics of a multi-output LLC resonant converter widely used in consumer electronics. The output characteristics of the multi-output LLC converter is derived from the assumption that the current and voltage to flow through the resonant network is sinusoidal and the duty loss is investigated. The simulation results are provided to verify the theoretic results.

• Journal of Electrical Engineering and Technology
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• v.13 no.1
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• pp.333-344
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• 2018

This proposed paper aims for the high efficiency contactless power transfer in household dc power distribution. A 300 W five-level diode clamped multi-level converter with 300 Vdc input dc link bus is employed for the power transferring task and the output voltage range is controlled at 48 Vdc. The inner and outer solenoid coils are used for inductive power transfer (IPT) transformer with the 200 kHz switching frequency for designed power density. Therefore, to achieve the converter efficiency above 95%, the LLC series resonant with fundamental harmonic analysis (FHA) and the calculated switching angles are used as an optimized tool for designing the system resonant tank. The validations of this approached topology are illustrated in both MATLAB/Simulink simulation and implementation.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.360-363
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• 2002

In the resonant converters which can provide high efficiency and high power density, the resonant voltage stress is about $4\~5$ times the input voltage. It needs the power switch with high ratings. This is a reason why the conduction loss is increased. In this paper, it proposes the alternately zero voltage switched forward, flyback multi resonant converter topology for reducing the voltage stress using alternately zero voltage switching technique. And the proposed AT forward MRC Is experimentally considered about the loop gain with HP4194A network analyzer

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.3
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• pp.177-187
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• 2009

This paper describes the gain characteristics of Multi-output LLC series resonant converter by using the new analytical method. Specially, using the Math-CAD simulated result, this paper analyzes an influence from the secondary leakage inductance of transformer. The theoretical results are verified through an experimental prototype of the 430W 3-output LLC resonant converter for 46inch PDP power module.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.4
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• pp.71-78
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• 2005

This paper proposes a novel multi-level energy recovery sustaining driver for AC PDP(Plasma Display Panel), which solves the problems of the conventional multi-level sustaining driver. While the conventional circuit improves the voltage md current stress of the switching elements in Weber circuit not only there are parasitic resonant currents between resonant inductors and parasitic capacitance and hard switching, but also the changing period between 0 and sustain voltage is too long. Comparing the proposed circuit with the conventional circuit, the number of components are reduced and the parasitic resonant currents in resonant inductors are eliminated Moreover the hard switching problem is solved by using CIM(Current Injection Method) and the operating frequency will be high as much as possible by removing Vs/2 sustain period. And the circuit operations of the proposed circuit are analyzed for each mode and the validity is verified by the simulations using PSpice program.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1322-1333
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• 2014

To track the sinusoidal current under stationary frame and suppress the effects of low-order grid harmonics, the multi-resonant quasi-proportional plus resonant (PR) controller has been extensively used for digitally controlled LCL-type pulse-width modulation (PWM) converters with capacitor-current-feedback active damping. However, designing the controller is difficult because of its high order and large number of parameters. Moreover, the computation and PWM delays of the digitally controlled system significantly affect damping performance. In this study, the delay effect is analyzed by using the Nyquist diagrams and the system stability constraint condition can be obtained based on the Nyquist stability criterion. Moreover, impact analysis of the control parameters on the current loop performance, that is, steady-state error and stability margin, identifies that different control parameters play different decisive roles in current loop performance. Based on the analysis, a simplified controller design method based on the system specifications is proposed. Following the method, two design examples are given, and the experimental results verify the practicability and feasibility of the proposed design method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.535-540
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• 2004

In this paper, We proposed a rectangular slot antenna with CPW feeder. Slot antennas fed by CPW are attractive due to the simple fabrication simplicity and ease of integration with active devices. This antenna consists of two parts, inner patch and outer patch to realize wide-band antenna by multi-frequency. Also, We fabricated a proposed rectangular slot antenna, confirm characteristics of multi-frequency by tuning antenna parameters, inner antenna's location and size. The experimental results show that each resonant frequency of a fabricated antenna is measured at almost 1, 9GHz, 2.8GHz, 3, 5GHz, 4, 9GHz. In radiation patterns each resonant frequency, radiation pattern 4-th resonant frequency is the same ad that of TM11 in patch antenna. Therefore, the experimental and theoretical results shows that a proposal rectangular slot antenna have triple resonant frequencies.

• Journal of Power Electronics
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• v.7 no.2
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• pp.124-131
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• 2007

In this paper, a novel type of auxiliary switched capacitor assisted edge resonant soft switching PWM resonant DC-DC converter with two simple auxiliary commutation lossless inductor snubbers is presented. The operation principle of this converter is described using the switching mode equivalent circuits. This newly developed multi resonant DC-DC converter can regulate its DC output AC power under a principle of constant frequency edge-resonant soft switching commutation by an asymmetrical PWM duty cycle control scheme. The high frequency power regulation and actual power characteristics of the proposed soft switching PWM resonant DC-DC converter are evaluated and discussed. The operating performances of the newly proposed soft switching inverter are represented based on simulation results from an applications point of view.