• Title/Summary/Keyword: Wide load range efficiency

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A Buck Converter with PLL-based PWM/PFM Integrated Control (PLL 기반 PWM/PFM 통합 제어 방식의 벅 컨버터)

  • Heo, Jung;Jeong, Hang-Geun
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.49 no.8
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    • pp.35-40
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    • 2012
  • In DC-DC converters, a PWM/PFM dual mode control method is commonly used to maintain a high efficiency over a wide range of load variation. Since the control mode is selected according to the load condition, the chip area is increased due to additional circuit for mode control and the optimum efficiency cannot be achieved around the mode transition point. To solve such problems, a new integrated control method is proposed in this paper, in which a PLL is used in the current mode PWM control circuit instead of an oscillator. The proposed integrated control method is verified through a design of a buck converter using PSIM simulation. Simulation of the complete buck converter circuit by Cadence Spectre showed a maximum efficiency of 94.7% at a load current of 250mA and an efficiency of 85.4% at a load current of 10mA under the light load condition.

Gateway Channel Hopping to Improve Transmission Efficiency in Long-range IoT Networks

  • Kim, Dae-Young;Kim, Seokhoon
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.13 no.3
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    • pp.1599-1610
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    • 2019
  • Intelligent services have expanded as Internet of Things (IoT) technology has evolved and new requirements emerge to accommodate various services. One new requirement is transmitting data over long distances with low-power. Researchers have developed low power wide area (LPWA) network technology to satisfy the requirement; this can improve IoT network infrastructure and increase the range of services. However, network coverage expansion causes several problems. The traffic load is concentrated at a specific gateway, which causes network congestion and leads to decreased transmission efficiency. Therefore, the approach proposed in this paper attempts to recognize and then avoid congestion through gateway channel hopping. The LPWA network employs multiple channels, so wireless channel hopping is available in a gateway. Devices that are not delay sensitive wait for the gateway to reappear on their wireless channel; delay sensitive devices change the wireless channel along the hopping gateway. Thus, the traffic load and congestion in each wireless channel can be reduced improving transmission efficiency. The proposed approach's performance is evaluated by computer simulation and verified in terms of transmission efficiency.

A High Efficiency Power Conversion Circuit with Wide ZVS Range for Sustaining Power Module of Large Size PDP (넓은 영전압 스위칭 범위를 갖는 대화면 PDP용 유지 전원단을 위한 고효율 전력 변환 회로)

  • Park, K.H.;Lee, W.J.;Youn, M.J.;Moon, G.W.
    • Proceedings of the KIPE Conference
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    • 2005.07a
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    • pp.279-282
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    • 2005
  • Recently, due to the launching of digital broadcasting service, a demand of PDP TV with large screen size is sharply rising. PDP power module is mainly divided into power factor correction (PFC) stage and sustaining power stage. Especially, sustaining power module has pulsating load characteristics. So, the hard switching at light load condition causes low efficiency and thermal problem. Therefore, a new power conversion circuit for sustaining power module of 60' PDP is proposed whose ZVS is obtained by additional ZVS tank. This paper presents properties of the proposed converter through mode analysis, numerical analysis. And a 900w prototype for sustaining power module of 60' PDP is produced to verify the analytic results. As an experimental results, ZVS is achieved from full load to 10% load variation and more than 92% of high efficiency is obtained at 10% load condition.

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Simple High Efficiency Full-Bridge DC-DC Converter using a Series Resonant Capacitor

  • Jeong, Gang-Youl;Kwon, Su-Han;Park, Geun-Yong
    • Journal of Electrical Engineering and Technology
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    • v.11 no.1
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    • pp.100-108
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    • 2016
  • This paper presents a simple high efficiency full-bridge DC-DC converter using a series resonant capacitor. The proposed converter achieves the zero voltage switching of the primary switches under a wide range of load conditions and reduces the high circulating current in the freewheeling mode using the leakage resonant inductance and the series resonant capacitor. Thus, the proposed converter overcomes the drawbacks of the conventional full-bridge DC-DC converter and improves its overall system efficiency. Its structure is simplified by using the leakage inductance of the transformer as the resonant inductance and omitting the DC output filter inductance. Also it can operate over a wide range of input voltages. In this paper, the operational principle, analysis and design example are described in detail. Finally, the experimental results from a 650W (24V/27A) prototype are demonstrated to confirm the operation, validity and features of the proposed converter.

Phase Locked Loop based Pulse Density Modulation Scheme for the Power Control of Induction Heating Applications

  • Nagarajan, Booma;Sathi, Rama Reddy
    • Journal of Power Electronics
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    • v.15 no.1
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    • pp.65-77
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    • 2015
  • Resonant converters are well suited for induction heating (IH) applications due to their advantages such as efficiency and power density. The control systems of these appliances should provide smooth and wide power control with fewer losses. In this paper, a simple phase locked loop (PLL) based variable duty cycle (VDC) pulse density modulation (PDM) power control scheme for use in class-D inverters for IH loads is proposed. This VDC PDM control method provides a wide power control range. This control scheme also achieves stable and efficient Zero-Voltage-Switching (ZVS) operation over a wide load range. Analysis and modeling of an IH load is done to perform a time domain simulation. The design and output power analysis of a class-D inverter are done for both the conventional pulse width modulation (PWM) and the proposed PLL based VDC PDM methods. The control principles of the proposed method are described in detail. The validity of the proposed control scheme is verified through MATLAB simulations. The PLL loop maintains operation closer to the resonant frequency irrespective of variations in the load parameters. The proposed control scheme provides a linear output power variation to simplify the control logic. A prototype of the class-D inverter system is implemented to validate the simulation results.

Hybrid DC-DC Converter For Power Efficiency Improvement Operating Over a Wide Load Power (넓은 부하전력에서 동작하는 전력 효율 향상을 위한 하이브리드 DC-DC 컨버터)

  • Woo, Ki-Chan;Mok, Jin-Won;Kim, Tae-Woo;Hwang, Seon-Kwang;Yang, Byung-Do
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.9
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    • pp.1763-1770
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    • 2016
  • This paper proposed hybrid converter to operate over a wide output load power. The switched-capacitor converter has a high efficiency at low load power and a low efficiency at high load power. On the contrary, the buck converter has a high efficiency at high load power and a low efficiency at low load power. The proposed hybrid converter has combination of the switched-capacitor converter and the buck converter. The switched-capacitor operates at low load power and buck converter operates at high load power, so that the hybrid converter is improved power efficiency at wide output load power. The hybrid converter was implemented with a $0.18{\mu}m$ CMOS process. The hybrid converter has a range of the load power between $50{\mu}W$and 100mW. The maximum power efficiencies are 93% and 77% at the buck converter and the switched-capacitor converter, respectively.

A Hybrid DC/DC Converter for EV OBCs Using Full-bridge and Resonant Converters with a Single Transformer

  • Hassan, Najam ul;Kim, Yoon-Jae;Han, Byung-Moon;Lee, Jun-Young
    • Journal of Power Electronics
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    • v.17 no.1
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    • pp.11-19
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    • 2017
  • This paper proposes a dc/dc converter for electric vehicle onboard chargers using a secondary resonant tank. To attain soft switching characteristics, such as zero voltage switching, magnetizing inductance has been used at the primary side of the transformer. The leakage inductance of the transformer is used as a resonant inductor on the secondary side to avoid the use of a separate inductor as resonance. The proposed converter is applicable for a wide load range. A 6.6KW prototype has been implemented for a wide range of load variations (250V, 330V, 360V, and 413V). A maximum efficiency of 97.4% is achieved at 413V.

A High Efficiency Power Conversion Circuit with Wide ZVS Range for Large Screen PDP Sustaining Power Module (넓은 영전압 스위칭 범위를 갖는 대화면 PDP용 유지전원단을 위한 고효율 전력 변환회로)

  • Park Kyung-Hwa;Moon Gun-Woo
    • The Transactions of the Korean Institute of Power Electronics
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    • v.10 no.6
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    • pp.578-586
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    • 2005
  • Recently, due to the launch of digital broadcasting service, the demand of Flat Panel Display (FPD) is sharply rising. Among them, the PDP is expected to be one of the most promising digital displays of next generation because of its large screen size, high resolution, thinness and board field of view. Meanwhile, the PDP uses ADS (Address Display-period Separation) scheme which divide one subfield into address and sustaining period to express the grey scale of images. Since the output of sustaining power module Is mostly used for sustaining period, the load of the sustaining power module can be considered as a pulsating load. Due to this particular load condition, if the wide ZVS range of the power switches is not guaranteed, the hard switching causes large amount of switching loss and serious thermal problem in power module. In this paper, a high efficiency power conversion circuit for 60' PDP sustaining power module which achieves wide ZVS range with the help of additional ZVS tank is proposed. According to the various gating methods, the different operations of the proposed converter are presented. And, to confirm the properties of the proposed converter, an experimental prototype of 900W power converter is constructed md tested. As a result, more than $92\%$ of high efficiency is obtained at $10\%$ load condition, and the ZVS operation is achieved from full load to $10\%$ load condition.

A high efficiency 200W Adaptor with new voltage-current driven synchronous rectfier (전압전류 혼합 구동방식의 동기정류기를 이용한 200W급 고효율 AC Adaptor에 관한 연구)

  • Won, Ki-Sik;Lee, Darl-Woo;Ahn, Tae-Young;Kim, Sung-Cheol;Jang, Chan-Gyu;Kim, Young-Joo
    • Proceedings of the KIEE Conference
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    • 2005.10c
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    • pp.182-185
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    • 2005
  • This paper presents a new voltage current driven method for the synchronous rectifier (SR) in a flyback topology. The proposed synchronous rectfier of voltage-current driven can operate at wide load range with high efficiency. The gate voltage of FET in the synchronous rectifier is easily controlled by resistor ratio. regardless of line and load fluctuation. The 200W (l2V/17A) prototype is built and achiveved efficiency as high as 90% at 4A, 93.2% at 7A and full load.

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Feasibility Study of Tapped Inductor Filter Assisted Soft-Switching PWM DC-DC Power Converter

  • Moisseev S.;Sato S;Hamada S;Wakaoka M
    • Proceedings of the KIPE Conference
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    • 2003.07a
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    • pp.231-234
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    • 2003
  • This paper presents a novel high frequency transformer linked full-bridge type soft-switching phase-shift PWM control scheme DC-DC power converter, which can be used as power conditioner fur small-scale fuel cell power generation system. Using full-bridge soft-switching DC-DC converter topology makes possible to use low voltage high performance MOSFETs to achieve high efficiency of the power conditioner. A tapped inductor filter is implemented in the proposed soft-switching converter topology to achieve soft-switching PWM constant high frequency operation for a wide load variation range. to minimize circulating and idling currents without using additional resonant circuit and auxiliary power switching devices. The practical effectiveness of the proposed soft-switching DC-DC converter is verified in laboratory level experiment with 1 kW 100kHz breadboard setup using power MOSFETs. Actual efficiency of 94-96$\%$ is obtained for the wide load range

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