Browsing by Author "Yu, Ming-Hung"

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A new multi-mode multi-input-multi-output (MIMO) converter in an efficient low-voltage energy harvesting system for a gas sensor
(2018-11-01)
Yu, Ming-Hung
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Chao, Paul C. -P.
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電子工程學系及電子研究所
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電控工程研究所
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Department of Electronics Engineering and Institute of Electronics
This paper presents a new multi-mode multi-input-multi-output (MIMO) converter with a battery for operating an energy harvesting (EH) system for gas sensors. In this EH system, the MIMO converter has a single DC-DC structure with multiple inputs and outputs. The converter is designed and tuned to harvest ambient light energy from a photovoltaic module, and it then provides regulated power at biases of 3.3 and 5V to charge the battery and/or to drive a gas sensor. The battery serves as a load to be charged by the MIMO or as a power source when the ambient light energy is insufficient to drive the gas sensor. For regulating the DC-DC converter, maximum power point tracking is implemented for each power path from inputs and outputs. The proposed MIMO converter has the least number of switches among existing converters. Experimental results reveal that the MIMO converter exhibits a high efficiency of 89.73% for a large power throughput of 0.9W for a gas sensor.
A new prediction model on the luminance of OLEDs subjected to different reverse biases for alleviating degradation in AMOLED displays
(2015-12-01)
Yu, Ming-Hung
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Tran, Trong-Hieu
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Hsu, Yen-Ping
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Chao, Paul C. -P.
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Lee, Kuei-Yu
A new prediction model for estimating luminance degradation of an OLED subjected to varied combinations of forward and reverse biases is proposed. To this end, the known increase in the voltage of OLEDs under long-time operation versus degraded emitted luminance is first-time ever considered to identify the degradation exponent as logarithm functions of elapsed time. With the identified degradation versus time, the degraded OLED luminance can be well predicted even subjected to varied combinations of forward and reverse biases. The established model is particularly useful for achieving required lifetime of modern AMOLED displays. Based on the model in terms of equations, the OLED parameters including forward, reverse bias stresses, and initial luminance can be applied to the model to accurately estimate the luminance variation during long-time operation. The estimation error between model predictions and experimental measurements is less than 1.6 %.
A New Single Inductor Bipolar Multiple Output (SIBMO) Boost Converter using Pulse Frequency Modulation (PFM) Control for OLED Drivers and Optical Transducers
(2015)
Chang, Chun-Kai
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Su, Chung-Hsin
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Kao, Yung-Hua
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Yu, Ming-Hung
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Sauter, Thilo
This study proposes a single-inductor bipolar multiple-output (SIBMO) boost converter utilizing pulse frequency (PFM) control for organic light-emitting diode (OLED) drivers and optical transducers. The purpose of the converter designed herein is to provide multiple voltage sources with opposite polarities to meet the requirements of various applications such as OLEDs or optical transducers. The bipolar voltage sources are essential for offering alternating driving voltages to extend the lifetime of OLEDs. The converter boosts the input of 2.8 V to two positive and two negative outputs, i.e., +12 V, +6 V, -12 V, and -6 V. Different from the commonly-used pulse width modulation (PWM), the constant on-time (COT) approach is adopted herein with a dynamic charging algorithm to automatically adjust the operating frequency, thus profiting from less circuit complexity, improvement of cross regulation, and high transfer efficiency in unbalanced load cases. The total maximum output power is 320 mW, as the switching frequency varies from 650 kHz to 0 Hz, and the maximum efficiency reaches 83.1% by simulation. The converter was fabricated by TSMC 0.25 mu m 1P3M high voltage CMOS technology for verification.
Efficiency Enhancement of PEDOT:PSS/Si Hybrid Solar Cells by Using Nanostructured Radial Junction and Antireflective Surface
(2013-08-14)
Chen, Jheng-Yuan
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Con, Celal
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Yu, Ming-Hung
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Cui, Bo
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Sun, Kien Wen
We demonstrate the implementation of a hybrid solar cell that comprises a surface nanostructured n-type Si and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate). The Si surface before deposition of the organic layer was nanostructured by using CsCl self-assembled nanoparticles as a hard mask and dry etching to form radial junction architectures and enhance light diffusion and absorption. Apart from the textured Si surface, processing parameters such as from metal-electrode shadow ratio, spin-coating rate, and surfactant addition were properly adjusted to improve overall cell performance. Our hybrid solar cells achieve the best performance under optimized cell parameters with a power conversion efficiency of 8.84% and short-circuit current density of 30.5 mA/cm(2). This combined technique provides a simple, scalable, and cost-effective process for fabricating hybrid solar cells.
Enhanced Performance of Organic Thin Film Solar Cells Using Electrodes with Nanoimprinted Light-Diffraction and Light-Diffusion Structures
(2014-05-14)
Chen, Jheng-Yuan
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Yu, Ming-Hung
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Chang, Chih-Yu
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Chao, Yi-Hsiang
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Sun, Kien Wen
An ITO substrate with periodic surface nanostructures was used to induce strong diffusion and diffraction of incident light. The nanostructures were fabricated using nanoimprint lithography on photoresist followed by coating of the ITO layer and organic materials with uniform morphology. The nanostructures embedded into the ITO layer were found to increase absorption in poly(3-hexylthiophene) : [6,6]-phenyl-C61-butyric acid methyl ester solar devices. The short-circuit current of the nanostructured organic solar cells improved from 7.07 to 10.76 mA/cm(2). This improvement was due to the increased effective optical path of absorbed light resulting from the trapping and scattering by the nanostructures.
Highly efficient poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)/Si hybrid solar cells with imprinted nanopyramid structures
(2013-09-23)
Chen, Jheng-Yuan
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Yu, Ming-Hung
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Chang, Shun-Fa
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Sun, Kien Wen
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應用化學系
High-efficiency hybrid solar cells based on nanostructured silicon and poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate), which were fabricated via a simple nanoimprint fabrication process, demonstrated an excellent power conversion efficiency of 10.86%. The complex and costly high-temperature photolithography and masking steps were replaced by techniques that are low-cost and capable of mass production. The nanopyramid structures fabricated on the silicon surface provided an antireflective effect and have a radial junction architecture that enhanced the light absorption and carrier collection efficiency. The short-circuit current density (J(sc)) of the hybrid solar cell with nanopyramid structures was greatly improved from 24.5 mA/cm(2) to 32.5 mA/cm(2) compared with that of a flat surface device. The highest solar cell efficiency was achieved on a 525 mu m-thick 2.3 Omega cm n-type Czochralski process (CZ) Si substrate with a designated area of 4 cm(2). (C) 2013 AIP Publishing LLC.
SINGLE-INPUT MULTI-OUTPUT CONVERTER WITH BACKUP BATTERY FOR ENERGY HARVESTING SYSTEM OF THE GAS SENSOR
(2017-01-01)
Yu, Ming-Hung
;
Chao, Paul C. -P.
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電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
This paper presents a single-input multi-output converter with backup battery for energy harvesting system of the gas sensor. Energy harvesting techniques used to catch energy from ambient light through photovoltaic (PV) modules as the main power source and regulate two outputs- 3.3V and 15V for different loads by a dc-dc converter. The backup battery is connected to input and output side of this system as a source and a load, when the PV energy more than the power of load, surplus energy charged in the rechargeable battery, when the ambient energy small than power of load, converter will storage power from PV cells, then charge power from battery and feed energy to the load. Finally, a multi-output converter for energy harvesting system is implemented to verify the precision of control strategy, light input and heavy input condition proposed in this paper.