• 전력전자학회논문지
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• 제23권3호
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• pp.225-230
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• 2018

This paper proposes a parametric design of an LLC resonant inverter used for a microwave oven. To improve the harmonic performance of the microwave oven, a current controller with a variable PI gain is proposed. Due to the recent strengthening of harmonics regulations, inverter control technology for microwave ovens is now required to satisfy harmonic performance. In an LLC resonant inverter, the voltage gain varies remarkably depending on the magnetron voltage, output power, and input voltage. To satisfy harmonic performance, a controller that can maintain operation in the zero-voltage switching (ZVS) region and control changes in voltage gain is required. The modified design of the LLC resonant inverter ensures ZVS operation even when the magnetron is heated. Application of the variable current controller improves harmonic control according to the instantaneous gain curve change. The validity of the proposed power control with a variable current controller is verified by experiments with a 1200 W microwave oven.

• 한국소음진동공학회논문집
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• 제21권8호
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• pp.741-751
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• 2011

Vibrations caused by automobile engine are absorbed mostly by a passive-type engine mount. However, user specifications for automobile vibrations require more stringent conditions and higher standard. Hence, active-type engine mounts have been developed to cope with such specifications. In this study, the active vibration absorber which can be attached to the sub-frame of automobile is used for the suppression of vibrations caused by engine. The active vibration absorbing system consists of sensor, actuator and controller where a control algorithm is implemented using DSP. The vibration caused by engine reveals harmonic disturbances varying with engine revolution. Therefore, the control algorithm should be able to cope with harmonic disturbances. In this study, the modified higher harmonic control technique which can selectively suppress harmonic disturbance is considered. Experimental results on automobile show that the proposed active vibration absorbing system is effective in suppressing vibrations caused by engine.

• Journal of international Conference on Electrical Machines and Systems
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• 제3권2호
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• pp.155-161
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• 2014

Industrial Static Var Generator (SVG) is typically applied at or near the load center to mitigate voltage fluctuation, flicker, phase unbalance, non-sine distortion or other load-related disturbance. Special attention is paid to the influence of grid voltage quality on SVG current, the non-sine distortion and unbalance of grid voltage causes not only the AC current distortion and unbalance but also the DC voltage fluctuation. In order to let the inverter voltage contain the fundamental negative sequence and harmonic component corresponding to the grid voltage, a new dual-loop control scheme is proposed to suppress the influence in this paper. The harmonic and negative sequence voltage decomposition algorithm and DC voltage control are also introduced. All these analyses can guide the practical applications. The simulation results verify the feasibility and effectiveness of the present control strategy and analyses.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2001년도 종합학술발표회 논문집 Vol.11 No.1
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• pp.222-226
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• 2001

In this paper, 2.4GHz RF Module using Even Harmonic Mixer(EHM) was designed and fabricated for Direct conversion(DC) system. By minimizing performance degradation of DC system with DC offset and LO radiation, the capability of minimization and one chip solution in wireless system was proposed. The designed EHM using anti-parallel diode pair represented 9dB conversion loss and about -60dBm 2LO leakage radiation in RF port, and output reflection and reverse transmission characteristic of low noise amplifier was improved. So superior DC offset suppression characteristic is expected. RF Module which consists of EHM, LNA, RF amplifier, Frequency synthesizer and Duplexer was designed and fabricated.

• 한국ITS학회 논문지
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• 제8권5호
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• pp.98-104
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• 2009

본 논문에서는 Push-Push 구조와 고임피던스 인버터를 이용하여 개선된 VCO를 설계 및 제작하였다. 두 개의 고조파 발진기를 Push-Push 구조로 결합시킴으로써 기본주파수 억압특성을 개선하였으며, 고조파 출력을 향상시켰다. 이에 따른 위상잡음 증가는 고임피던스 인버터를 이용하여 공진기와 병렬선로 사이의 결합특성 개선을 통하여 억제하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1250-1252
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• 2003

This Paper presents Sigma-Delta Modulation(SDM) schemes to generate switching waveform for a high-power factor boost-type rectifier. The SDM scheme can be implemented by simple digital algorithm unlike conventional PWM schemes with several hardware, and has the characteristics of spectrum-spreading and noise-shaping effects, which are profitable in harmonic reduction of input current in the boost-type rectifier. The comparison results of their spectrum performances shows that the 1st-order SDM has better harmonic suppression effect than conventional PWM scheme and Dithered SDM scheme.

• Journal of Power Electronics
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• 제19권5호
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• pp.1289-1302
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• 2019

In this paper, an optimal allocation method of a hybrid active power filter in an active distribution network is designed based on the differential evolution algorithm to resolve the harmonic generation problem when a distributed generation system is connected to the grid. A distributed generation system model in the calculation of power flow is established. An improved back/forward sweep algorithm and a decoupling algorithm are proposed for fundamental power flow and harmonic power flow. On this basis, a multi-objective optimization allocation model of the location and capacity of a hybrid filter in an active distribution network is built, and an optimal allocation scheme of the hybrid active power filter based on the differential evolution algorithm is proposed. To verify the effect of the harmonic suppression of the designed scheme, simulation analysis in an IEEE-33 nodes model and an experimental analysis on a test platform of a microgrid are adopted.

• 한국전자파학회논문지
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• 제8권2호
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• pp.107-115
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• 1997

본 논문에서는 23 GHz 국간(Point-to-point) 통신용 Push-Push발진기를 Split Ring 공진기(Split Ring Resonator)를 사용하여 설계, 제작하였다. Split Ring 공진기(SRR)는 둥가회로를 이용한 이론적인 해석 및 MPIE(Mixed Potential Integral Equation)수칙해석 툴을 이용 해석하였다. 이 해석된 결과를 사용하여 전송 모드로 마이크로 스트립 라인과 결합된 SRR를 분석하였다. 제작된 발진기은 23 GHz에서 출력 전력은 4dBm, 기본 주파수 및 3차 고조파 억제는 - 20 dBc, - 34 dBc의 특성과 발진주파수에서 1 MHz offset에서 -109 d dEc/Hz의 SSB위상잡음 및 1.4%의 변환 효율을 나타내었다. 이 실험결과는 이론 및 시뮬레이션 결과와 일치함을 알 수 있다.

• 한국전자파학회논문지
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• 제15권6호
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• pp.560-566
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• 2004

본 논문은 6 ㎓의 주파수를 2체배 하여 12 ㎓의 신호원을 얻는 광대역 능동 주파수 2체배기를 PHEMT를 사용하여 제작하였다. 설계된 주파수 체배기는 핀치오프 영역의 바이어스점을 가지며, 동작주파수 영역에서 무조건 안정인 특성을 갖도록 하기 위하여 입력매칭단과 바이어스 라인 사이에 직렬 RC회로를 제안하였다. 측정 결과0 ㏈m의 입력전력에 대하여 12 KHz 1,7 ㏈m의 2차 고조파 출력을 얻었고, 6 ㎓에서 -27.5 dBc의 기본주파수 억압과 -18 ㏈c의 3차 고조파 억압특성을 보였으며, 1.8 ㎓의 3 ㏈ 대역폭을 나타내었다.

• Journal of electromagnetic engineering and science
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• 제11권3호
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• pp.143-151
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• 2011

This paper presents a survey of recent wireless power transfer systems. The issue of wireless power transfer is to achieve a highly efficient system with small positioning errors of the facilities setting. Several theories have been presented to obtain precise system design. This paper presents a summary of design theory for short range power transfer systems and detailed formulations based on a circuit model and an array of infinitesimal dipoles. In addition to these theories, this paper introduces a coil array scheme for improving the efficiency for off axis coils. In the microwave range, tightly coupled resonators provide a highly efficient power transfer system. This paper present san-overlay resonator array consisting of half wavelength microstrip line resonators on the substrate with electromagnetically coupled parasitic elements placed above the bottom resonators. The tight couplings between the waveguide and the load resonator give strong power transmission and achieve a highly efficient system, and enables a contact-less power transfer railroad. Its basic theory and a demonstration of a toy vehicle operating with this system are presented. In the last topic of this paper, harmonic suppression from the rectenna is discussed with respect to acircular microstrip antenna with slits and stubs.