Browsing by Author "Tsai, Jen-Chieh"

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800V Ultra-High-Voltage Start-up Mechanism for Pre-regulator in Power Factor Correction (PFC) Controller
(2011)
Chen, Chi-Lin
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Tsai, Jen-Chieh
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Chen, Yi-Ting
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Ni, Chia-Lung
;
Chen, Chun-Yen
The on-chip 800V ultra-high-voltage (UHV) start-up mechanism was introduced in this paper. Using the UHV start-up mechanism can minimize the current leakage at the AC input and remove the need of external start-up resistor and capacitor. As a result, the standby current can be decreased to improve the efficiency of AC-DC systems. Furthermore, the zero current detection (ZCD) circuit was used here to ensure the work of the pre-regulator. An inductance coil will detect the primary inductance current and reflect the voltage, which is detected by ZCD circuit to provide the energy to the pre-regulator. The test circuit fabricated in TSMC 800V UHV process can show the highly-integrated PFC controller. Experimental results demonstrate low THD of 8%, which results in high PF of 99%. Certainly, high efficiency of 95% can be ensured at the output power of 50W.
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.
ADVERSARIAL DOMAIN SEPARATION AND ADAPTATION
(2017-01-01)
Tsai, Jen-Chieh
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Chien, Jen-Tzung
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電機工程學系
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Department of Electrical and Computer Engineering
Traditional domain adaptation methods attempted to learn the shared representation for distribution matching between source domain and target domain where the individual information in both domains was not characterized. Such a solution suffers from the mixing problem of individual information with the shared features which considerably constrains the performance for domain adaptation. To relax this constraint, it is crucial to extract both shared information and individual information. This study captures both information via a new domain separation network where the shared features are extracted and purified via separate modeling of individual information in both domains. In particular, a hybrid adversarial learning is incorporated in a separation network as well as an adaptation network where the associated discriminators are jointly trained for domain separation and adaptation according to the minmax optimization over separation loss and domain discrepancy, respectively. Experiments on different tasks show the merit of using the proposed adversarial domain separation and adaptation.
Anaerobic biotransformation of fluorene and phenanthrene by sulfate-reducing bacteria and identification of biotransformation pathway
(2009-05-30)
Tsai, Jen-Chieh
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Kumar, Mathava
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Lin, Jih-Gaw
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環境工程研究所
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Institute of Environmental Engineering
In the present study, anaerobic biotransformation of fluorene and phenanthrene by sulfate-reducing bacteria (SRB) was investigated and biotransformation pathways were proposed. SRB was enriched from anaerobic swine wastewater sludge and its abundance was determined by the fluorescence in situ hybridization (FISH) technique. Batch anaerobic biotransformation studies were conducted with fluorene (5 mg L(-1)), phenanthrene (5 mg L(-1)) and a mixture of the two (10 mg L(-1)). After 21 d of incubation. 88% of fluorene and 65% of phenanthrene were biotransformed by SRB. In contrast to previous studies, a decrease in biotransformation efficiency was observed in the presence of both fluorene and phenanthrene. Throughout the study, sulfate reduction was coupled with biotransformation of fluorene and phenanthrene. However, no increase in bacterial cell density was observed in the presence of an inhibitor, i.e. molybdate. Identification of metabolites by gas chromatography-mass spectrometry (GC-MS) revealed that fluorene and phenanthrene were biotransformed through a sequence of hydration and hydrolysis reactions followed by decarboxylation with the formation of p-cresol (only in the phenanthrene system) and phenol. The metabolites identified suggest novel biotransformation pathways of fluorene and phenenthrene. (C) 2008 Elsevier B.V. All rights reserved.
Biodegradation of soil-applied polycyclic aromatic hydrocarbons by sulfate-reducing bacterial consortium
(2009)
Kumar, Mathava
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Wu, Pei-Chi
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Tsai, Jen-Chieh
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Lin, Jih-Gaw
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環境工程研究所
In the present study, the potential of polycyclic aromatic hydrocarbons (PAHs) biodegradation by sulfate-reducing bacterial consortium enriched from piggery wastewater was investigated. The batch experiments of soil-applied PAH biodegradation were conducted with a mixture of PAHs, i.e., naphthalene, fluorene, phenanthrene, fluoranthene and pyrene, at a concentration of 50 mu g of each PAH per g of soil. A central composite design (CCD) was applied to determine the experimental conditions of each batch assay. The pH, biomass and ethanol concentrations were selected as independent variables and the PAH removal percentage was considered as a dependent variable. The optimal conditions for PAH biodegradation were found to be a pH between 4 and 6.5, an ethanol concentration less than 35 mg/L and a biomass concentration greater than 65 mg/L. Bench scale experiments were carried out at the optimal conditions. At the end of experiment (27 d), total PAH removals by biodegradation and volatilization were around 74% and 20%, respectively. The order of PAH removal was naphthalene, phenanthrene, fluorene, fluoranthene, and pyrene. Throughout the study, PAH biodegradation was in good correlation with sulfate reduction. Results of the kinetics study indicated a competitive inhibition between PAHs investigated.
Boundary Conduction Mode Controlled Power Factor Corrector With Line Voltage Recovery and Total Harmonic Distortion Improvement Techniques
(2014-07-01)
Su, Yi-Ping
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Ni, Chia-Lung
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Chen, Chun-Yen
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Chen, Yi-Ting
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Tsai, Jen-Chieh
The proposed line voltage recovery (LVR) and the total harmonic distortion improvement (THDI) technique improve power factor (PF) and total harmonic distortion (THD) over a wide line voltage range in boundary conduction mode controlled power factor corrector (PFC). The LVR detects the input line root-mean-square voltage to generate the digital equivalent code to the THDI for optimizing the THD by tuning the on-time value at different line voltages. In addition, the LVR and the THDI provide a feedforward path to reduce the ripple of the feedback voltage for further improving the THD. Therefore, the PFC controller can keep high PF and low THD over a wide line voltage. Experimental results demonstrate that the peak PF value is 0.998 and the minimum THD is 1.7% by the test circuit fabricated in a TSMC 800-V ultrahigh-voltage process with the universal line voltage range of 90-264 V.
Determination of optimal phenanthrene, sulfate and biomass concentrations for anaerobic biodegradation of phenanthrene by sulfate-reducing bacteria and elucidation of metabolic pathway
(2009-11-15)
Tsai, Jen-Chieh
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Kumar, Mathava
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Chang, Sue-Min
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Lin, Jih-Gaw
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環境工程研究所
Anaerobic biodegradation of phenanthrene (PHE) was investigated using an enrichment culture consists predominantly of sulfate-reducing bacteria (87 +/- 6%). Aqueous biodegradation experiments were designed using the rotatable central composite design with five levels. The designed concentrations were 2-50 mg L(-1) for PHE, 480-3360 mg L(-1) for sulfate, and 5-50 mg L(-1) for initial biomass. Experimental results indicated that the biomass concentration was the most significant variable, followed by the sulfate and PHE concentrations. The desirability functions methodology (DFM) was applied to find out the maximum specific PHE removal rate (R(s)). The maximum R(s) of 9.0 mg g(-1) VSS d(-1) within the designed ranges was obtained when the initial PHE, sulfate and biomass concentrations were 18.5, 841 and 50 mg L(-1), respectively. The R(s) observed in the present study was higher than the values reported in the previous studies. Subsequently, a confirmation study was performed under the optimal conditions. and the results matched well with the R(s) estimated using DFM. Samples collected during PHE biodegradation experiments inferred the formation of two novel metabolic intermediates, 2-methyl-5-hydroxybenzaldehyde and 1-propenyl-benzene, and subsequently degraded to p-cresol, phenol and hydrocarbons. (C) 2009 Elsevier B.V. All rights reserved.
Dual Modulation Technique for High Efficiency in High Switching Buck Converters Over a Wide Load Range
(2010)
Tsai, Jen-Chieh
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Huang, Tsung-Ying
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Lai, Wang-Wei
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Chen, Ke-Horng
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電控工程研究所
The design of a compact size switching converter under high switching operation causes a drastically decreasing in power conversion efficiency. This paper presents a dual modulation technique to improve the power conversion efficiency with a little increase in output ripple. Especially, the trade-off between the output ripple and the efficiency can meet the requirement of the portable devices. Simulation results show that the converter can operate at 5 MHz with a supply voltage from 3V to 4.5V. The output voltage ripple can be kept smaller than 30mV when load current varies from 20mA to 800mA. Besides, the power efficiency is higher than 85% over a wide load current range.
Dual Modulation Technique for High Efficiency in High-Switching Buck Converters Over a Wide Load Range
(2011-07-01)
Tsai, Jen-Chieh
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Huang, Tsung-Ying
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Lai, Wang-Wei
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Chen, Ke-Horng
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電控工程研究所
A dual modulation technique to improve power conversion efficiency with minimal increase in output voltage ripple is presented. The worsening switching noise caused by parasitic resistance and inductance due to high-switching operation can also be alleviated by the proposed ac ripple detector. Furthermore, the dual modulation method can speed up the load transient response since the switching frequency can increase to 5 MHz during the transient period. At very light loads, the switching frequency is always kept higher than the acoustic frequency to avoid noisy sound. Experiment results show that the converter operates at 5 MHz using a small inductor of 1 mu H. The load transient response time is shorter than 3 mu s when load current changes from 150 to 450 mA or vice versa. Power efficiency is kept higher than 85% over a wide load current range. Specifically, light efficiency can be raised to about 45% above that of the conventional design.
High-PF and Ultra-Low-THD Power Factor Correction Controller by Sinusoidal-Wave Synthesis and Optimized THD Control
(2013)
Chang, Chih-Wei
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Ni, Chia-Lung
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Tsai, Jen-Chieh
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Chen, Yi-Ting
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Chen, Chun-Yen
the proposed sinusoidal-wave synthesis (SWS) and the optimized THD control (OTC) improve power factor (PF) and total harmonic distortion (THD) over a wide line voltage range. The SWS detects the input line root-mean-square (rms) voltage to generate the digital equivalent code to the OTC for optimizing the THD by tuning the on-time value. Besides, the SWS and the OTC provide a feedforward path to reduce the ripple of the feedback voltage for further improving the THD. Therefore, the PFC converter can keep high PF and low THD over a wide line voltage. Experimental results demonstrate the PF is higher than 0.99 and the THD is 1.7% at V-AC of 90 - 110V by the test circuit fabricated in TSMC 800V UHV process.
Modified Hysteretic Current Control (MHCC) for Improving Transient Response of Boost Converter
(2011-08-01)
Tsai, Jen-Chieh
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Chen, Chi-Lin
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Lee, Yu-Huei
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Yang, Hong-Yuan
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Hsu, Ming-Shen
This paper proposes a modulated hysteretic current control (MHCC) technique to improve the transient response of a DC-DC boost converter, which suffers from low bandwidth due to the existence of the right-half-plane (RHP) zero. The MHCC technique can automatically adjust the on-time value to rapidly increase the inductor current, as well as to shorten the transient response time. In addition, based on the characteristic of the RHP zero, the compensation poles and zero are deliberately adjusted to achieve fast transient response in case of load transient condition and adequate phase margin in steady state. Experimental results show the improvement of transient recovery time over 7.2 times in the load transient response compared with the conventional boost converter design when the load current changes from light to heavy or vice versa. The power consumption overhead is merely 1%.
Nano-bubble flotation technology with coagulation process for the cost-effective treatment of chemical mechanical polishing wastewater
(2007-12-01)
Tsai, Jen-Chieh
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Kumar, Mathava
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Chen, Shen-Yi
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Lin, Jih-Gaw
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環境工程研究所
The feasibility of nano-bubble flotation technology (NBFT) with coagulation/flocculation process for the enhanced treatment of chemical mechanical polishing (CMP) wastewater was investigated through laboratory and pilot-scale experiments. As a precursor, the effective combination of activator/collector was identified using a laboratory-scale flotation reactor. The results showed that polyaluminum chloride (PAC)/sodium oleate (NaOl) was the best combination of activator/collector, respectively and its application in the NBFT with coagulation process increased the wastewater clarification efficiency by 40% as compared with traditional coagulation/flocculation process. More than 95% turbidity, total solids and total silica removal efficiencies were observed in the pilot-scale flotation experiments. From the results, it was found that NBFT with coagulation process could be performed effectively at an optimum PAC concentration of 50-60 mg/L (as Al), NaOl concentration of 5-10 mg/L with a recycle ratio of 10-20% and I h hydraulic retention time HRT. The cost and performance assessment reflected that CMP wastewater could be treated efficiently at a minimum cost using the present approach. (c) 2007 Elsevier B.V. All rights reserved.
Perturbation On-time (POT) Control and Inhibit Time Control (ITC) in Suppression of THD of Power Factor Correction (PFC) Design
(2011)
Tsai, Jen-Chieh
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Chen, Chi-Lin
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Chen, Yi-Ting
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Ni, Chia-Lung
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Chen, Chun-Yen
The paper presented the perturbation on-time (POT) control technique to suppress the total harmonic distortion (THD) to improve the performance of the power factor correction (PFC) in the AC-DC converter. Simultaneously, it can improve the efficiency through the proposed inhibit time control (ITC) mechanism at low AC input voltage. The test circuit fabricated in TSMC 800V UHV process can show the highly-integrated PFC controller. Experimental results demonstrate low THD of 8%, which results in high PF of 99%. Besides, high efficiency of 95% can be ensured at the output power of 90W.
Perturbation On-Time (POT) Technique in Power Factor Correction (PFC) Controller for Low Total Harmonic Distortion and High Power Factor
(2013-01-01)
Tsai, Jen-Chieh
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Chen, Chi-Lin
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Chen, Yi-Ting
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Ni, Chia-Lung
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Chen, Chun-Yen
The proposed perturbation on-time technique suppresses total harmonic distortion (THD) and, thus, improves the power factor in the power factor correction (PFC) controller. Besides, the adaptive control of the minimum off time by the proposed inhibit time control can improve efficiency even at low ac input voltage. Therefore, highly integrated PFC converter fabricated in the TSMC 800-V ultrahigh voltage process can achieve low THD of 6%, high PF of 99%, and high efficiency of 95% at the output power of 90 W.
Triple Loop Modulation (TLM) for High Reliability and Efficiency in a Power Factor Correction (PFC) System
(2013-07-01)
Tsai, Jen-Chieh
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Ni, Chia-Lung
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Chen, Chi-Lin
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Chen, Yi-Ting
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Chen, Chun-Yen
The proposed triple loop modulation (TLM) can ensure reliability of the power factor correction (PFC) system due to the improvement of transient response. In conventional design, low bandwidth of less than 20Hz that rejects ac source of 60/120 Hz coupling deteriorates system reliability in case of output load variation. Contrarily, the proposed TLM can automatically adjust bandwidth to rapidly increase or decrease inductor current to shorten transient response time. Besides, in the steady state, system stability can be guaranteed by low-frequency compensation pole without being affected by the TLM. The test circuit fabricated in a VIS 500 V UHV laterally diffused metal-oxide-semiconductor transistor process demonstrates that the highly integrated PFC controller with the proposed TLM has high power factor of 99%, high efficiency of 95%, and high power driving capability of about 90 W. The improvement in transient response is twofold faster than in conventional PFC design with output load variation from 90 to 20W and vice versa.
Triple Loop Modulation (TLM) for High Reliability and Efficiency in Power Factor Correction (PFC) System
(2012)
Tsai, Jen-Chieh
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Ni, Chia-Lung
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Chen, Chun-Yen
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Chen, Yi-Ting
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Chen, Chi-Lin
Reliability of the Power Factor Correction (PFC) system was improved by fast transient response using the proposed triple loop modulation (TLM). Low bandwidth of less than 20 Hz that rejects AC source of 60/120 Hz coupling deteriorated system reliability in case of output load variation. The proposed TLM can automatically adjust bandwidth to rapidly increase or decrease inductor current in order to shorten transient response time. In steady state, system stability can be guaranteed by low-frequency compensation pole without being affected by TLM. The test circuit fabricated in VIS 500 V UHV LDMOS process demonstrated the performance of the highly-integrated PFC controller with the proposed TLM. Experimental results showed that the PFC system with TLM has high PF of 99%, high efficiency of 95%, and high power driving capability of about 90 W. The improvement in transient response is twofold faster than conventional PFC design with output load variation from 90W to 45 W and vice versa.
Variable Sampling Slope (VSS) and No-Deadtime Ramp Generator (NDRG) Techniques for Closed-Loop Interleaving Power Factor Correction (PFC) Design with Suppression of Current Mismatch
(2012)
Chen, Chun-Yen
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Peng, Ruei Hong
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Tsai, Jen-Chieh
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Kang, Yu-Chi
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Ni, Chia-Lung
the proposed interleaving power factor correction (PFC) can effectively reduce the size of the AC-DC converter for portable electronics. Fully integrated variable sampling slope (VSS) technique can provide precise phase regulation under variable line voltage. Besides, the no-deadtime ramp generator (NDRG) records the previous status to modify the sequent on-time value to achieve current sharing for suppressing the total harmonic distortion (THD) and restraining the input current ripple, EMI filter, and the size of input inductor. Therefore, more power can be provided by the proposed interleaving PFC than that of single-phase PFC. Simultaneously, the drawback of the peak current twice than the average current in the Boundary control mode (BCM) can be greatly reduced. The test circuit fabricated in the TSMC 0.5 mu m 800V UHV process shows the highly integrated interleaving PFC can deliver high power of 180W with improved phase regulation precision.
Versatility of fluorene metabolite (phenol) in fluorene biodegradation by a sulfate reducing culture
(2011-06-01)
Kumar, Mathava
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Liao, Wei-Chih
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Tsai, Jen-Chieh
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Lin, Jih-Gaw
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環境工程研究所
Biodegradability of fluorene and the versatility of fluorene metabolite (i.e. phenol) in fluorene biodegradation by a sulfate-reducing enrichment culture were investigated. Batch experiments (with 5 mg l(-1) fluorene) were designed via the central composite design to examine the effects of sulfate (5-35 mM) and biomass (5-50 mg l(-1)) concentrations (variables) on fluorene degradation (response). The experimental results revealed that fluorene removal was more influenced by the biomass concentration than the sulfate concentration. The optimal sulfate and biomass concentrations for fluorene biodegradation (90% removal) were found to be 14.4 mM and 37.8 mg l(-1), respectively. Under the optimal conditions, a set of biodegradation experiments were repeated to evaluate both the biodegradability of fluorene metabolite and the potential effect of phenol accumulation on fluorene degradation. The outcomes indicated a slow phenol degradation rate, i.e. 0.02 mg l(-1) d(-1). Moreover, a small reduction in the fluorene biodegradation efficiency was observed in the presence and accumulation of phenol. However, this sulfate reducing culture is a valuable resource for the simultaneous degradation of fluorene and phenol. (C) 2011 Elsevier Ltd. All rights reserved.