Current Sensing Methods for Standby Power Control of Digital-Controlled DC/DC Converter

Yen-Shin Lai,Zih-Jie Su,Chia-An Yeh,Fumikazu Takahashi,Masahiro Hamaogi 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

The main theme of this paper is to study the current sensing methods for standby power reduction control of digital-controlled DC/DC converter. These methods include using transformer of full-bridge converter, coupling inductor and ORing MOSFET. The most suitable sensing method was verified with a digital-controlled 500W class DC/DC converter (input/output voltage: 400V/12V). Experimental results derived from digital-controlled DC/DC converter using the TI DSP (TMS320F2812) as the control platform show that current sensed by voltage across ORing MOSFET method provides superb solution. This method offers linear relationship between output voltage of sensing circuit and load current while not causing response delay under standby conditions and thereby truly reflecting accurate standby conditions.

Effect of Sampling Frequency of A/D Converter on Controller Stability and Bandwidth of Digital-Controlled Power Converter

Ye-Then Chang,Yen-Shin Lai 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

Due to the merits of flexibility, reduction of analog components and no aging issue of external components, digital-controlled power converter becomes very promising. It is required to derive the discrete model of power converter for digital-power control. The effect of sampling frequency of A/D converter on the digital-controlled power converter is also very essential to the performance. The objective of this paper is to present a discrete-time model of power converter for digital-controlled applications and to investigate the effect of sampling frequency of A/D converter stability and bandwidth of digital controller. It will be shown as the sampling frequency increases, the controller bandwidth can be increased to speed up the transient while reducing the phase margin. The results shown in this paper will provide a quantitative reference for digital controller design. Experimental results will be presented for confirmation.

Successful Enrichment of Rarely Found Candidatus Anammoxoglobus propionicus from Leachate Sludge

( Shu Chuan Hsu ),( Yen Chun Lai ),( Ping Heng Hsieh ),( Pun Jen Cheng ),( Suen Shin Wong ),( Chun Hsiung Hung ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.7

Bacteria that mediate the anaerobic oxidation of ammonium (anammox) have been detected in natural ecosystems, as well as various wastewater treatment systems. In this study, sludge from a particular landfill leachate anaerobic treatment system was selected as the incubation seed for anammox microorganism enrichment owing to its possible anammox activity. Transmission electron microscopy observation, denaturing gradient gel electrophoresis analysis, and cloning/sequencing techniques were applied to identify the diversity of anammox microorganisms throughout the incubation. During the early stage of operation, the diversity of anammox microorganisms was similar to the original complex microbes in the seed sludge. However, as incubation time increased, the anammox microorganism diversity within the system that was originally dominated by Candidatus (Ca.) Brocadia sp. was replaced by Ca. Anammoxoglobus propionicus. The domination of Ca. Anammoxoglobus propionicus produced a stable removal of ammonia (70 mg-N/l) and nitrite (90 mg-N/l), and the total nitrogen removal efficiency was maintained at nearly 95%. The fluorescence in situ hybridization results showed that Ca. Anammoxoglobus propionicus was successfully enriched from 1.8 ± 0.6% initially to 65 ± 5% after 481 days of operation. Therefore, the present results demonstrated the feasibility of enriching Ca. Anammoxoglobus propionicus from leachate sludge, even though the original cell count was extremely low. Application of this seldom found anammox organism could offer an alternative to current ammonia-nitrogen treatment.

Delay of Surgery for Spinal Metastasis due to the COVID-19 Outbreak Affected Patient Outcomes

Chia-Jung Hsieh,Chun-Yu Wu,Yen-Heng Lin,Yu-Cheng Huang,Wen-Chi Yang,Tom Wei-Wu Chen,Wei-Li Ma,Wei-Hsin Lin,Feng-Ming Hsu,Furen Xiao,Shih-Hung Yang,Dar-Ming Lai,Chang-Mu Chen,Shin-Yi Chao,Fon-Yih Tsuan 대한척추신경외과학회 2023 Neurospine Vol.20 No.4

Objective: The present study is to analyze the effects of the coronavirus disease 2019 (COVID 2019) outbreak and the subsequent lockdown on the outcomes of spinal metastasis patients. Methods: The study was a retrospective analysis of data from a prospective cohort study. All patients underwent surgical intervention for spinal metastases between January 2019 and December 2021 and had at least 3 months of postoperative follow-up. The primary outcome was overall mortality during the 4 different stages (pre-COVID-19 era, COVID-19 pandemic except in Taiwan, national lockdown, lifting of the lockdown). The secondary outcomes were the oncological severity scores, medical/surgical accessibility, and patient functional outcome during the 4 periods as well as survival/mortality. Results: A total of 233 patients were included. The overall mortality rate was 41.20%. During the Taiwan lockdown, more patients received palliative surgery than other surgical methods, and no total en bloc spondylectomy was performed. The time from surgeon visit to operation was approximately doubled after the COVID-19 outbreak in Taiwan (75.97, 86.63, 168.79, and 166.91 hours in the 4 periods, respectively). The estimated survival probability was highest after the national lockdown was lifted and lowest during the lockdown. In the multivariate analysis, increased risk of mortality was observed with delay of surgery, with emergency surgery having a higher risk with delays above 33 hours, urgent surgery (below 59 and above 111 hours), and elective surgery (above 332 hours). Conclusion: The COVID-19 pandemic and related policies have altered daily clinical practice and negatively impacted the survival of patients with spinal metastases.

Arm Exoskeleton Rehabilitation Robot with Assistive System for Patient after Stroke

Guan De Lee,Wei-Wen Wang,Kai-Wen Lee,Sheng-Yen Lin,Li-Chen Fu,Jin-Shin Lai,Wen-Shiang Chen,Jer-Junn Luh 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

Exercise dosage is proven to be an important factor in the physical treatment. Robot assistive approach can improve the rehabilitation quality and evaluate patient’s recovery quantitatively. This paper presents kinematic structure, assistive control system, and integrated F/T sensor for an upper limb rehabilitation robot. By using the human arm dynamic, there are three rehabilitation modes presented in this paper: active mode, assistive mode, and passive mode. In assistive mode, we have two strategies to implement it. One is to amplify interactive torque, and the other is to apply assist-as-needed concept. The goal of this mode is to assist patients to finish motion tasks. The rehabilitation robot under investigation has 7 degree of freedom (DOF) actuated by DC motors, which are programmed to drive the robot arm in the 3D space. To validate our control design, some realistic experiments are conducted and its satisfactory performance is demonstrated. This work is approved clinical testing by the Department of Health, Executive Yuan, R.O.C. So far, we are demonstrating the effect of our controller.

Current Ripple Reduction Technique of DC/DC Converter

Ye-Then Chang,Chia-An Yeh,Masahiro Hamaogi,Fumikazu Takahashi,Yen-Shin Lai 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

This paper presents a novel method to reduce the current ripple caused by the variation of inductor for a DC/DC converter. The presented method is to increase the switching frequency to keep constant current ripple when the inductance changes. Therefore, no extra component is required. The problem will be described first and the related method is presented. An experimental DC/DC converter is implemented which is with input voltage of 12 V, output voltage of 1.5 V, output current of 10 A, and switching frequency of 200-250 ㎑. Finally, experimental results derived from the designed digital-controlled DC/DC converter are included for confirmation.