• Title/Summary/Keyword: operating frequency

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DUAL DUTY CYCLE CONTROLLED SOFT-SWITCHING HIGH FREQUENCY INVERTER USING AUXILIARY REVERSE BLOCKING SWITCHED RESONANT CAPACITOR

  • Bishwajit, Saha;Suh, Ki-Young;Lee, Hyun-Woo;Mutsuo, Nakaoka
    • Proceedings of the KIEE Conference
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    • 2006.10d
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    • pp.129-131
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    • 2006
  • This paper presents a new ZVS-PWM high frequency inverter. The ZVS operation is achieved in the whole load range by using a simple auxiliary reverse blocking switch in parallel with series resonant capacitor. The operating principle and the operating characteristics of the new high frequency circuit treated here are illustrated and evaluated on the basis of simulation results. It was examined that the complete soft switching operation can be achieved even for low power setting ranges by introducing the high frequency dual duty cycle control scheme. In the proposed high frequency inverter treated here, the dual mode pulse modulation control strategy of the asymmetrical PWM in the higher power setting ranges and the lower power setting ones, the output power of this high frequency inverter could introduce in order to extend soft switching operation ranges. Dual duty cycle is used to provide a wide range of output power regulation that is important in many high frequency inverter applications. It is more suitable for induction heating applications the operation and control principle of the proposed high frequency inverter are described and verified through simulated results.

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Zero Voltage Switching Boost H-Bridge AC Power Converter for Induction Heating Cooker

  • Kwon, Soon-Kurl;Saha, Bishwajit
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.21 no.4
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    • pp.19-27
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    • 2007
  • This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost H-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switch mode equivalent circuits and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft-switching(ZVS) operation ranges, and the power dissipation as compared with those of the conventional type high frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation(PWM) and pulse density modulation(PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

Pulse Density Modulated Zero Voltage Soft-Switching High-Frequency Inverter with Single Switch for Xenon Gas Dielectric Barrier Discharge Lamp Dimming

  • Sugimura, Hisayuki;Suh, Ki-Young;Lee, Hyun-Woo;Nakaoka, Mutsuo
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2006.05a
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    • pp.391-394
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    • 2006
  • This paper presents soft switching zero voltage switching high frequency inverter for rare gas fluorescent lamp using dielectric-barrier discharge phenomenon. The simple high-frequency inverter can completely achieve stable zero voltage soft switching (ZVS) commutation for wide its output power regulation ranges and load variations under its constant high frequency pulse density modulation (PDM) scheme. Its transient and steady state operating principle is originally described and discussed for a constant high-frequency PDM control strategy under a stable ZVS operation commutation, together with its output effective power regulation characteristics-based on the high frequency PDM strategy. The experimental operating performances of this high frequency Inverter are illustrated as compared with computer simulation results and experimental ones. Its light dimming characteristics due to power regulation scheme are evaluated and discussed on the basis of simulation and experimental results. The feasible effectiveness of this high frequency inverter appliance implemented here is proven from the practical point of view.

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High-Frequency Zero Current Soft Switching Inverter with Pulse Density Modulation for Induction Heated Roller

  • Kang, Shin-Chul;Mun, Sang-Pil
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.22 no.7
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    • pp.49-57
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    • 2008
  • This paper presents a voltage source type half-bridge series resonant high frequency (HF) inverter for induction heated fixing roller in copy machines. This high-frequency inverter works under zero current soft switching (ZCS) commutation and has wide power regulation range due to employing a pulse density modulation (PDM) scheme. Transient and steady state operating modes of the inverter are presented in this paper together with its PDM-based power regulation system. Experimental operating performances of the developed HF-ZCS inverter as well as power losses and actual efficiency are discussed and compared with computer simulation results.

Study of Stirling Cryocooler Performance with Different Operating Frequency (작동주파수에 따른 스터링 극저온 냉동기의 특성에 관한 연구)

  • 박성제;홍용주;고득용;김효봉;오군섭;김종학
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2001.02a
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    • pp.159-162
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    • 2001
  • A Stirling cryocooler is relatively compact, reliable, commercially available, and uses helium as a working fluid. The FPFD stirling cryocooler consists of two compressor pistons driven by linear motors which makes pressure waves and a pneumatically driven displacer piston with regenerator. It is the most suitable design for a mechanical cryocooler utilized in night vision environment. In order to get optimum operating frequency, natural frequency of piston and displacer, optimum phase angle between piston and displacer, cooling capacity, performance tests of the Stirling cryocooler by the frequency characteristics were performed.

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A Study on the Control of Characteristic in the Analog Active Element for System Stabilization (시스템 안정화를 위한 아날로그 능동 소자의 특성 제어에 관한 연구)

  • Lee, Geun Ho;Bang, Jun Ho;Kim, Dong Yong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.6B
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    • pp.114-114
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    • 2000
  • In this paper, a current comparative frequency automatic tuning circuit for the CMOS bandpass filter are designed with the new architecture. And also, when the designed circuit is compared the typical tuning circuit, it has very simple architecture that is composed of the current comparator and charge pump and operated in 2V power supply. The proposed tuning circuit automatically compensate the difference between the operating current of the integrator and the reference current which is specified. Using CMOS 0.25um parameter, a CMOS bandpass active filter with center frequency(f0= 100MHz) is designed, and according to the transister size the variation of the center frequency is simulated. As the HSPIC simulation results, the tuning operating of the proposed current comparative frequency automatic tuning circuit is verified.

A 37.5kV A Class Power Supply for Diagnostic X -ray by High-Frequency Resonant Inverter Type (37.5kVA급 고주파 공진형 인버터식 진단 X선 전원장치)

  • 김학성;유동욱;임근희;완충연
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.12
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    • pp.113-121
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    • 1996
  • This paper presents a 37.5kVA (125kVp, 300mA) high frequency inverter type power supply for diagonostic X-ray generator with two HFHV (high-frequency high-voltage) isolating transformers. The output regulations, X-ray tuve voltage and tube current, are obtained by two high frequency inverters with the each other feedback PI controller and operating time switch for selecting shooting time and synchronizing two inverters. The operating modes and design consideration of the proposed power supply are given. Issues in the design of two HFHV isolating transformersfors high volage genrating and filament heating are discussed. Experimental results are presented to verify the performance of the designed power supply for varying load conditions. The proposed apparatus has several advnatages, e.g., the fast rising time of tube voltae, accuracy and reduced component size etc.

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A study on the Control of Characteristic in the Analog Active Element for System Stabilization (시스템 안정화를 위한 아날로그 능동 소자의 특성 제어에 관한 연구)

  • 이근호;방준호;김동용
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.6B
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    • pp.1114-1119
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    • 2000
  • In this paper, a current comparative frequency automatic tuning circuit for the CMOS bandpass filter are designed with the new architecture. And also, when the designed circuit is compared the typical tuning circuit, it has very simple architecture that is composed of the current comparator and charge pump and operated in 2V power supply. The proposed tuning circuit automatically compensate the difference between the operating current of the integrator and the reference current which is specified. Using CMOS 0.25um parameter, a CMOS bandpass active filter with center frequency(fo=100MHz) is designed, and according to the transister size the variation of the center frequency is simulated. As the HSPICE simulation results, the tuning operating of the proposed current comparative frequency automatic tuning circuit is verified.

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An Analysis of Nursing Work of Operating Room Nurses (수술실 간호사의 간호업무 분석)

  • Kwon, Sung-Bok;Park, Young-Sook;Kim, Dong-Oak;Yi, Yeo-Jin;Lee, Eun-Hee;Cho, Kyung-Sook
    • Journal of Korean Academy of Nursing Administration
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    • v.14 no.1
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    • pp.72-84
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    • 2008
  • Purpose: The purpose of this study was to identify nurses' duties and tasks for job analysis of the nurses in the operating room. Methods: This study was descriptive investigation research using the 3-point likert scale questionnaires and the level of importance, difficulty and the frequency of each duty and task were analyzed. Data were collected by 422 OR nurses from 57 hospitals. Results: Job of OR nurses included 13 duties and 105 tasks. The 13 duties were 'management of operative patient' 'assistive work for operation' 'supportive work for operation' 'infection control in OR' 'management of equipments and instruments for operation' 'administrating medicine for operation' 'supplies management for operation' 'safety management for operation' 'environmental management for operating room' 'administrative work for operation' 'education for operating room personnel' 'development of operation procedure books' and 'elf development of OR personnel' Conclusion: This study identified duties and tasks performed by OR nurses. Based on these results, the importance, frequency, and difficulty in this study will provide research evidence for developing training programs for OR nurses.

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Study on the frequency of self-excited pulse jet

  • Wang, Jian;Li, Jiangyun;Guan, Kai;Ma, Tianyou
    • International Journal of Fluid Machinery and Systems
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    • v.6 no.4
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    • pp.206-212
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    • 2013
  • Self-excited pulse jet is a specific nozzle with a closed chamber which can change a continuous jet into a pulse one. Energy of the pulse jet can be output not only unevenly but also with multifrequency. With the peak pressure of pulse jet, the hitting power would be 2~2.5 times higher than that of continuous jet. In order to reveal the correlation between the self-excited pulse frequency and nozzle diameter ratio, nozzle spacing and operating pressure, the model of 3D unsteady cavitation model has been used. We found that with the same nozzle structure parameters and the different operating pressure, the self-excited frequency and the width of peak crest are different, but the wave profiles are similar. With FFT, we also found that the less bandwidth of amplitude in low frequency range will lead to the wider wave crest of outlet velocity in its time domain, and the larger force of the strike will be gained. By studying the St of self-excite nozzle, not only the frequency of a certain nozzle can be predicted, but also a nozzle structure with a certain frequency can be designed.