An adaptive sliding mode controller for buck converter in continuous conduction mode

Author name used in this publication: Chi K. TseAuthor name used in this publication: Martin K. H. CheungRefereed conference paper2003-2004 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

A fixed-frequency pulsewidth modulation based quasi-sliding-mode controller for buck converters

Author name used in this publication: Chi K. TseAuthor name used in this publication: Martin K. H. Cheung2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A pulse-width-modulation based sliding mode controller for buck converters

Author name used in this publication: Martin K. H. CheungAuthor name used in this publication: Chi K. TseRefereed conference paper2003-2004 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

On the practical design of a sliding mode voltage controlled buck converter

Author name used in this publication: Martin K. H. CheungAuthor name used in this publication: Chi K. Tse2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Adaptive feedforward and feedback control schemes for sliding mode controlled power converters

Author name used in this publication: Chi K. TseAuthor name used in this publication: Martin K. H. Cheung2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Physical activity assessment by accelerometry in people with heart failure

Background: International guidelines for physical activity recommend at least 150 min per week of moderate-to-vigorous physical activity (MVPA) for adults, including those with cardiac disease. There is yet to be consensus on the most appropriate way to categorise raw accelerometer data into behaviourally relevant metrics such as intensity, especially in chronic disease populations. Therefore the aim of this study was to estimate acceleration values corresponding to inactivity and MVPA during daily living activities of patients with heart failure (HF), via calibration with oxygen consumption (VO2) and to compare these values to previously published, commonly applied PA intensity thresholds which are based on healthy adults. Methods: Twenty-two adults with HF (mean age 71 ± 14 years) undertook a range of daily living activities (including laying down, sitting, standing and walking) whilst measuring PA via wrist- and hip-worn accelerometers and VO2 via indirect calorimetry. Raw accelerometer output was used to compute PA in units of milligravity (mg). Energy expenditure across each of the activities was converted into measured METs (VO2/resting metabolic rate) and standard METs (VO2/3.5 ml/kg/min). PA energy costs were also compared with predicted METs in the compendium of physical activities. Location specific activity intensity thresholds were established via multilevel mixed effects linear regression and receiver operator characteristic curve analysis. A leave-one-out method was used to cross-validate the thresholds. Results: Accelerometer values corresponding with intensity thresholds for inactivity ( 50% lower than previously published intensity thresholds for both wrists and waist accelerometers (inactivity: 16.7 to 18.6 mg versus 45.8 mg; MVPA: 43.1 to 49.0 mg versus 93.2 to 100 mg). Measured METs were higher than both standard METs (34-35%) and predicted METs (45-105%) across all standing and walking activities. Conclusion: HF specific accelerometer intensity thresholds for inactivity and MVPA are lower than previously published thresholds based on healthy adults, due to lower resting metabolic rate and greater energy expenditure during daily living activities for HF patients. Trial registration: Clinical trials.gov NCT03659877, retrospectively registered on September 6th 2018.This article is freely available via Open Access. Click on the Publisher URL to access it via the publisher's site.This study was undertaken as part of a PhD, which was funded by a University of Exeter Postgraduate Studentship Grant. The funders were not involved in design of the study, data collection, analysis, and interpretation of data, and in writing the manuscript.published version, accepted versio

Experimental investigation of a sliding mode controlled buck converter

This paper details an experimental evaluation of a sliding mode controlled buck converter. Different tests are performed to study the behavior of the SMVC converter under different operating conditions and design parameters. Careful attention is given to associate the observed experimental phenomenon with the theoretical principles. © 2004IEEE.link_to_subscribed_fulltex

Adaptive feedforward and feedback control schemes for sliding mode controlled power converters

A major disadvantage of applying sliding mode control to dc/dc converters is that the steady-state switching frequency is affected by line and load variations. This is undesirable as it complicates the design of the input and output filters. To reduce switching frequency deviation in the events of line and load variations, an adaptive feedforward control scheme that varies the hysteresis band according to the change of line input voltage and an adaptive feedback control scheme that varies the control parameter (i.e., sliding coefficient) according to the change of the output load are proposed. This paper presents a thorough investigation into the problem and the effectiveness of the proposed solutions. In addition, methods of implementing the proposed adaptive control strategies are discussed. Experimental results confirm that the adaptive control schemes are capable of reducing the switching frequency variations caused by both line and load variations. © 2006 IEEE.link_to_subscribed_fulltex