Browsing by Author "Kang, Yu-Chai"

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120% Harvesting Energy Improvement by Maximum Power Extracting Control for High Sustainability Magnetic Power Monitoring and Harvesting System
(2015-04-01)
Huang, Tzu-Chi
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Du, Ming-Jhe
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Kang, Yu-Chai
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Peng, Ruei-Hong
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Chen, Ke-Horng
The magnetic energy harvesting (MEH) circuit and the power monitoring system are proposed in this paper to enlarge the system sustainability on wireless sensing or the monitoring system. The proposed MEH circuit harvests magnetic power on power wires through a power sensing current transformer (CT) and charges power monitoring system. The MEH circuit includes the direct ac-dc rectifier and the maximum power extracting (MPE) control circuit. The direct ac-dc rectifier can directly rectify ac input to the dc output current. The proposed MPE control fits the characteristic of magnetic energy source compared to the conventional resistor emulation maximum power point tracking method. Owing to continuous tracking the maximum power of the CT, 120% harvesting power improvement can be achieved under the same CT\'s sensing current. Peak efficiency of 82% can be achieved under the sensing current of 8 A. The test chip is fabricated in 0.25 mu m CMOS process with an active area of 0.98 mm(2).
92% High Efficiency and Low Current Mismatch Interleaving Power Factor Correction Controller With Variable Sampling Slope and Automatic Loading Detection Techniques
(2013-11-01)
Su, Yi-Ping
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Chen, Chun-Yen
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Ni, Chia-Lung
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Kang, Yu-Chai
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Chen, Yi-Ting
This paper proposes the dual nondeadtime variable sampling slope technique to carry out precise phase sensing and suppress phase error in interleaving power factor correction (PFC) controller over a whole ac switching cycle for low current mismatch. Furthermore, the proposed automatic loading detection (ALD) technique can keep efficiency higher than 92% over a wide load range due to accurately controlling the ON/OFF of dual phases. The test circuit fabricated in the TSMC 0.5-mu m 800-V UHV process shows that the highly integrated interleaving PFC can deliver a high power of 180 W and a high efficiency of 95% at an output power of 180 W.
A Battery-Free 217 nW Static Control Power Buck Converter for Wireless RF Energy Harvesting With alpha-Calibrated Dynamic On/Off Time and Adaptive Phase Lead Control
(2012-04-01)
Huang, Tzu-Chi
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Hsieh, Chun-Yu
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Yang, Yao-Yi
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Lee, Yu-Huei
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Kang, Yu-Chai
Abattery-free nano-power buck converter with a proposed dynamic on/off time (DOOT) control can achieve high conversion efficiency over a wide load range. The DOOT control can predict the on/off time at different input voltages without a power consuming zero current detection (ZCD) circuit, as well as suppress static power in idle periods. To adapt to the fluctuations in a harvesting system, the proposed alpha-calibration scheme guarantees accurate ZCD over process, voltage variation, and temperature (PVT) in the DOOT to improve power conversion efficiency. Furthermore, the adaptive phase lead (APL) mechanism can improve inherent propagation delay attributable to low-power and non-ideal comparator, thus improving load regulation by a maximum of 30 mV. The test chip was implemented in 0.25-mu m CMOS process with a die area of 0.39 mm(2). Experimental results showed 95% peak efficiency, low static power of 217 nW and good load regulation of 0.1 mV/mA, which are suitable for RF energy harvesting applications.
A Direct AC-DC and DC-DC Cross-Source Energy Harvesting Circuit with Analog Iterating-Based MPPT Technique with 72.5% Conversion Efficiency and 94.6% Tracking Efficiency
(2016-08)
Chen, Shin-Hao
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Huang, Tzu-Chi
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Ng, Shao Siang
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Lin, Kuei-Liang
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Du, Ming-Jhe
The proposed cross-source energy (CSE) harvesting system accepts universal energy sources, including the ac and dc sources. The buck-boost conversion of CSE automatically converts ac or dc input into dc output without being limited by the type of universal energy source. The CSE technique simultaneously supplies the regulated output for the system loading and the battery charging output. A test chip fabricated in the VIS Bipolar, CMOS, and DMOS (BCD) process can optimally derive harvest energy with 72.5% power efficiency when one solar input source is used. A backup converter is designed to complement the CSE technique to guarantee the regulation of output voltage. The proposed analog iterating-based (AIB) maximum power point tracking (MPPT) technique achieves 94.6% tracking efficiency without complex data calculation and storage, which are better results compared with those of previous research.
Non-invasion Power Monitoring with 120% Harvesting Energy Improvement by Maximum Power Extracting Control for High Sustainability Power Meter System
(2012)
Huang, Tzu-Chi
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Du, Ming-Jhe
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Yang, Yao-Yi
;
Lee, Yu-Huei
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Kang, Yu-Chai
Magnetic energy harvesting (MEH) circuit for system sustainability and power monitoring system with a novel dual-wire current transformer (DWCT) are proposed in this paper. MEH circuit simultaneously senses and harvests the magnetic energy. DWCT has the benefits of non-invasion measurement (NIM) and is easy to use. The designed direct AC-DC rectifier with maximum power extracting (MPE) control fits the characteristic of magnetic energy source. Thus, 120% harvesting power improvement can be achieved under the same sensing current.
Quasiresonant Control With a Dynamic Frequency Selector and Constant Current Startup Technique for 92% Peak Efficiency and 85% Light-Load Efficiency Flyback Converter
(2014-09-01)
Kang, Yu-Chai
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Chiu, Chao-Chang
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Lin, Moris
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Yeh, Chih-Pu
;
Lin, Jinq-Min
The proposed quasiresonant control scheme can be widely used in a dc-dc flyback converter because it can achieve high efficiency with minimized external components. The proposed dynamic frequency selector improves conversion efficiency especially at light loads to meet the requirement of green power since the converter automatically switches to the discontinuous conduction mode for reducing the switching frequency and the switching power loss. Furthermore, low quiescent current can be guaranteed by the constant current startup circuit to further reduce power loss after the startup procedure. The test chip fabricated in VIS 0.5 mu m 500 V UHV process occupies an active silicon area of 3.6 mm(2). The peak efficiency can achieve 92% at load of 80 W and 85% efficiency at light load of 5W.