Browsing by Author "Chen, Wei-Dar"

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A battery charge controller realized by a flyback converter with digital primary side regulation for mobile phones
(2014-08-01)
Chao, Paul C. -P.
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Chen, Wei-Dar
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Wu, Ruo-Hua
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電機工程學系
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Department of Electrical and Computer Engineering
A flyback converter with digital control designed and implemented for a lithium battery charging system is proposed in this study. As opposed to the requirement of both voltage and current feedbacks for a conventional flyback converter, this study proposes a converter structure that needs only one voltage feedback to stabilize converter output for implementing the designed battery charging techniques. This single feedback of voltage is made possible by so-called "primary side regulation (PSR)", which in hardware senses the output voltage using an auxiliary winding in the isolating transformer of the flyback converter that is operated in DC-DC discontinuous current mode. The adoption of PSR also enables the elimination of the opto-coupler that is often used in conventional converters for feedback signals. Another essential part of the converter is the proposition of a new a duty control method which regulate successfully the output current by only one feedback voltage signal. The proposed battery charging design consists of three consecutive modes, trickle current (TC), CC and CV. At TC and CC, a duty control method is adopted, which is able to regulate the output current by sensing only the output voltage. Both simulation and experimental results show a 7 % error deviated from targeted output current. As for CV, a proportional-integral controller is designed and implemented to regulate the output voltage. The overall experimental results show a favorable performance of the proposed charging method with proposed PSR-flyback converter.
A fast battery charging algorithm for an intelligent PV system with capability of on-line temperature compensation
(2013-09-01)
Chao, Paul C. -P.
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Chen, Wei-Dar
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Cheng, Chun-Wei
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影像與生醫光電研究所
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電機工程學系
This study presents a battery fast-charging mechanism for an intelligent generic photovoltaic (PV) system and also a pulse-charging method for the on-line temperature compensation. The fuzzy logic control (FLC) is adopted for fast maximum power point tracking (MPPT) of the PV system. Along with proposed battery charging algorithms, the controller presented in this study is named a fuzzy battery-managing controller (FBMC). The fast battery charging by this controller does not only prolong battery lifetime by restoring the maximum battery state of charge (SOC) in the shortest time but also with the temperature compensation. The designed charging algorithm consists of three different stages, namely constant current (CC), pulse charging and trickle charging. In the CC mode, the current at maximum power of the PV array is used for fast charging. The pulse charging mode is next adopted to contain temperature rise while maintaining relatively fast charging speed. To prevent battery damage by charging as battery capacity is close to its full status, 100 % SOC, the float charging mode is finally activated by further decreasing charging currents. Simulations are conducted via Powersim to validate the FBMC performance and the PV system model. The FBMC is next implemented by a DSP module (TMS320F2812) in order to adjust the switching duty cycle during operations of the buck converter. Finally, experimental results were compared with a general constant current and/or voltage method. The results show favorable performance of the propose charging method.
A Miniaturized Electromagnetic Generator With Planar Coils and Its Energy Harvest Circuit
(2009-10-01)
Liao, Lun-De
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Chao, Paul C. -P.
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Chen, Jian-Ting
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Chen, Wei-Dar
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Hsu, Wei-Hsuan
This study presents design, analysis and experiment of a miniaturized rotary generator in size of 10 10 2 mm and its compact energy harvest circuit chip. The designed generator consists of patterned planar copper coils and a multipolar hard magnet ring made of NdFeB. To perform modeling, a harmonic-like magnetic field model along the circumferential path of each magnetic pole is assumed with the assistance from measured peak magnetic flux densities. This is followed by the application of Faraday's law to predict generated electromotive forces (EMFs) in terms of the relative rotational speed between the magnet ring and coils. The genetic algorithm (GA) is next applied to optimize the critical dimensions of the miniaturized generator. The theoretical model of this power microgenerator is evaluated and compared with experimental results, and it is found that the analytical simulation shows a good agreement with the experimental results. The optimized generator offers 4.5 V and 7.23m W in root mean square (rms) at 10 000 r/min. With microgenerator successfully fabricated, a novel energy harvest circuit employing Dickson charge pump is designed and fabricated via the 0.35-um process offered by National Chip Implementation Center (CIC) of Taiwan. This charge pump circuit owns the merit of almost-zero thresholds of employed metal-oxide-semiconductor (MOS) transistors, enabling the conversion of low-power alternating current (ac) signals by the microgenerator to direct current (dc) ones.
A Multi-Touch Interface Circuit for a Large-Sized Capacitive Touch Panel
(2010)
Ruan, Juan-Yao
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Chao, Paul C. -P.
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Chen, Wei-Dar
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
This study presents a multi-touch sensing circuit for large-sized (more than 12 inches) capacitive touch panel. A new AC sensing technique is developed to enable the touch sensing in a large-sized capacitive touch panel. This novel designs of multi-touch sensing circuit lies in the operation principles through a 4X4 ITO film sensor array, a low-disturbance array circuit, a capacitance to voltage converter circuit and the proposed design procedure of chip parameters by circuit simulation. Furthermore, the sequence control for the array is generated by an FPGA module to accomplish the operation of the whole circuit. Some of objectives are to reduce environmental disturbance of the panel and to distinguish multi-touching locations from the panel. The corresponding output voltages of multi-touch sensing circuit are output in proportional to location touched by a human finger. Finally, the whole circuit is implemented by using TSMC 0.35 mu m 2P4M process. The circuit output voltages are used to distinguish touch locations by a proposed algorithm.
A New Compensation Method for Emission Degradation in an AMOLED Display Via an External Algorithm, New Pixel Circuit, and Models of Prior Measurements
(2014-03-01)
Lee, Kuei-Yu
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Hsu, Yen-Ping
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Chao, Paul C. -P.
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Chen, Wei-Dar
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電機工程學系
A new external algorithm with sensing circuit are proposed to compensate AMOLED display degradation. The compensation is enabled by first evaluating degradation level of OLEDs based on the OLED anode voltages detected by a newly-designed sensing subcircuit. According to sensed voltages, the external algorithm selects appropriate built-in models to compensate OLED degradation with the aim to achieve expected OLED emitted luminance. The models are established based on prior measurements to prescribe the relations between luminance and current and luminance and voltage of each OLED. In this way of compensation, the proposed method is able to incorporate negative effects of OLED degradation aggravation while increasing driving current to compensate the original decay in OLED luminance. Moreover, another algorithm along with the 4T0.5C pixel circuit as presented in prior studies are adopted to compensate process variation in among pixels for improving the emission uniformity of an AMOLED panel. Experiments are conducted by combining the external algorithm with sensing circuit and the pixel circuit to validate the performances of compensating and alleviating OLED degradation.
A Novel 3D Optical Proximity Sensor Panel and its Readout Circuit
(2010)
Lin, Tzu-Yang
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Chao, Paul C. -P.
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Chen, Wei-Dar
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Tsai, Che-Hung
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電子工程學系及電子研究所
This study presents a novel 3D optical proximity sensor (3D OPS) array panel. The panel is capable of detecting the objectives centimeters away from the panel surface. This device is composed of light-emitting diodes and home-made polymer photo-detectors (PPDs). The novel design of the circuit is the operation principle through active pixel circuit, sampling circuit, amplifier circuit and the decision of proposed chip parameters is determined by circuit simulation. The circuit is regarded low power and low cost as the design principle. The control sequence of the aforementioned circuit module is generated by an FPGA board to realize the operation of the whole circuit. The readout circuit is able to remove background current, and to detect the corresponding output voltage of photocurrent that is received by the PPD via reflections of the measured object. A human machine interface is built by LABVIEW to create 3D vision tracing of sensed object, validating the effectiveness of the 3D OPS.
Design and realization of a high resolution (640 x 480) SWIR image acquisition system
(2014-08-01)
Chen, Jian-Ruei
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Chao, Paul C. -P.
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Tsai, Che-Hung
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Chen, Wei-Dar
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電機工程學系
A new image acquisition system module for extracting signals of high-resolution short wave infrared (SWIR) from a focal plane array (FPA) is presented in this study. The short wave infrared (SWIR-with wavelength about 900-1,700 nm) images have been proven its unique values in many applications such as military, semiconductor inspection and aviation security. The designs for the SWIR data acquisition system module consists of digitization and acquisition of FPA signals, design of synchronous dynamic random access memory controller and real-time image signal transformation and display. Three major steps involved towards a successful SWIR module-(1) Selection of hardware ICs according to specification for the FPA; (2) Design of a timing generator for the image acquisition system to control FPA and other ICs by Verilog HDL programming; (3) Integrate the individual modules on a PCB. The SWIR image output signals are successfully generated in the format of National Television System Committee (NSTC), which can be displayed on a common NTSC monitor, flat panel displays with an AV input terminal or a CRT display in a favorable speed of frame rate at 30 per second.
Design and Realization of High Resolution (640x480) SWIR Image Acquisition System
(2013-01-01)
Chao, Paul C. -P.
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Chen, Jian-Ruei
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Tsai, Che-Hung
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Chen, Wei-Dar
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影像與生醫光電研究所
Maximum power tracking of a generic photovoltaic system via a fuzzy controller and a two-stage DC-DC converter
(2012-09-01)
Chao, Paul C. -P.
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Chen, Wei-Dar
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Chang, Chih-Kuo
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影像與生醫光電研究所
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電機工程學系
This study presents a new two-stage DC-DC converter for maximum power point tracking (MPPT) and a voltage boost of a generic photovoltaic (PV) system. An intelligent MPPT of PV system based on fuzzy logic control (FLC) is presented to adaptively design the proposed fuzzy controlled MPPT controller (FC-MPPTC) while a voltage boost controller (VBC) is used to fix the output voltage to a voltage level that is higher than the required operating voltage to the back-end grid impedance. Modeling and simulation on the PV system and the DC-DC converter circuit are achieved by state-space and the software Powersim. The PV string considered has the rated power around 600 VA under varied partial shadings. The FC-MPPTC and VBC are designed and realized by a DSP module (TMS320F2812) to adjust the duty cycle in the two-stage DC-DC converter. A special FLC algorithm is forged to render an MPPT faster and more accurate than conventional MPPT technique, perturb and observe (P&O). The simulations are intended to validate the performance of the proposed FC-MPPTC. Experiments are conducted and results show that MPPT can be achieved in a fast pace and the efficiency reaches over 90 %, even up to 96 %. It is also found that the optimized tracking speed of the proposed FC-MPPTC is in fact more stable and faster than the general P&O method with the boost voltage capable of offering a stable DC output.
Optimal design and fabrication of ITO/organic photonic crystals in polymer light-emitting diodes using a focused ion beam
(2010-05-01)
Tsai, Che-Hung
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Liao, Lun-De
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Luo, Yi-Shiun
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Chao, Paul C. -P.
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Chen, En-Chen
This study aims to achieve high directionality and large extraction of light emission from polymer light-emitting diodes via optimizing photonic crystals (PCs). The optimization is achieved through the optical modeling using a 3D finite-difference time-domain (FDTD) method and the intelligent numerical optimization technique, genetic algorithm (GA). In results, the PC period, depth and filling factor can be found. The FDTD method has been proven very effective for modeling complex multilayer PLED devices in which the electron-transporting layer is only a few tens of nanometers away from a metallic layer. On the other hand, GA is a powerful tool to cope with a complicated optimization problem with multiple variables to optimize. The optimized PCs are later fabricated by focused ion beams (FIB) for the PLED. With desired PCs, an increase of the extraction efficiency in excess of 46% is achieved experimentally and the 3D FDTD calculation explains this result faithfully. (C) 2009 Elsevier B.V. All rights reserved.
Optimizing angular placements of the LEDs in a LCD backlight module for maximizing optical efficiency
(2013-09-01)
Chao, Paul C. -P.
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Tsai, Che-Hung
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Li, Jiun-De
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Chen, Wei-Dar
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影像與生醫光電研究所
This study aims to optimize angular placements of the LEDs with novel cone-shaped caps for achieving high optical efficiency in an ultra-thin, directly-lit RGB LED backlight unit (BLU) for large-sized LCD-TVs. This novel lens cap is used as a diffuser with the purpose to gain higher efficiency and provide satisfactory uniformity over a display panel. To this aim, the outer surface of the novel lens is coated with aluminum for mirroring effects to reflect most of the LED emitted light horizontally and then reflect the light at the BLU boundaries, finally to the output plane. Since the emitted white light from LEDs result from color-mixing of three individual RGB chips in a LED package, the addition of the LED cap however deteriorates the aforementioned expected color mixing. The optimal design on angular placements of LEDs presented in this study for satisfactory color-mixing and emission uniformity is achieved by necessary optics simulations via TracePro, followed by utilizing an intelligent numerical optimization technique, genetic algorithm (GA). The design parameters for GA optimization are different combinations of LED placement angles in a backlight module. Favorable color balance is shown achievable in terms of high low color difference resulted. Finally, experiments are conducted, which successfully validate the expected performance of color balance and emission uniformity for a novel cone-shaped LED lens with optimized angular placements in a large-area backlight module.