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Your search keyword '"Chang, Yong-Nong"' showing total 90 results
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90 results on '"Chang, Yong-Nong"'

1. A Single-Stage Electrolytic-Capacitor-Free AC–DC LED Driver With High Power Factor and Soft Switching Characteristics

Author

Cheng, Hung-Liang, Chang, Yong-Nong, Hwang, Lain-Chyr, and Tu, Tsung-Han

Abstract

This article proposes a single-stage ac/dc converter for driving high-power light-emitting diodes. The circuit topology mainly includes two modified Ćuk converters that are interleaved operated. The front semi-stage of Ćuk converter operates like a boost converter while the second semi-stage operates like a buck converter. The boost converters are operated in discontinuous-conduction mode to play the role of power factor corrector. In the buck converters, the two energy-storage inductors are replaced by a coupled inductor. The mutual inductance current of the coupled inductor is almost constant and continuously flows to the output terminal. Therefore, the output voltage ripple can be effectively reduced without using large electrolytic capacitors. In addition, the proposed circuit does not require the use of any snubber circuit or active clamping circuit. All active switches operate at zero-voltage switching on, and all diodes operate at zero-current switching off. This article analyzes the operation modes of the circuit; derives mathematical equations; and designs component parameters. Finally, 180-W prototype circuit was built and tested. The experimental results show that the conversion efficiency at rated power operation is 96.6%; the power factor is as high as 0.996; and the total harmonic distortion of current is 7.18%. The performance is satisfactory and verifies the feasibility of the proposed circuit.

Published
2024
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14. The impact of switching strategies on power quality for integral cycle controllers

Author

Chang, Yong Nong, Heydt, Gerald Thomas, and Liu, Yazhou

Subjects
Electronics -- Research, Business, Computers, Electronics, Electronics and electrical industries
Abstract

Integral cycle controllers (ICCs) are used for load power control. ICCs are switched at an integral number of cycles to effect this control. The load current for such controllers has an impact on the distribution supply bus: the impact occurs for low frequency (subsynchronous) phenomena and high frequency (supersynchronous) phenomena. Subsynchronous impact includes flicker on the distribution bus, and supersynchronous phenomena includes supply transformer core loss. The management of these power quality issues is discussed in terms of selecting the controller switching strategy. An innovative concept of group frequencies is discussed. Index Terms--Harmonics, integral cycle controller, power electronics, power quality.

Published
2003

30. Backstepping direct thrust force control for sensorless PMLSM drive.

Author

Ting, Chen‐Sheng, Chang, Yong‐Nong, and Chen, Yen‐Yo

Abstract

This study presents an analytic designing approach for the sensorless direct thrust force control (DTFC) of permanent magnet linear synchronous motor (PMLSM). A modified stator flux estimator developed by use of an adaptive mechanism and correction factors is devoted to measuring the stator flux linkage and the mover's position. The parameters of the flux estimator are adjusted in advance through an off‐line identification process to increase the accuracy of estimation. Based on the principle of backstepping control, the reference q‐axis flux command, which is equivalent to the thrust force command, is first obtained from the Lyapunov functional analysis. Then, the reference d‐axis flux command is calculated according to the characteristics of stator flux linkage. The voltage control strategy is constructed to stabilise the global system and ensure the convergence of DTFC. Compared to the conventional direct torque/thrust control, the proposed control scheme can apply the space vector modulation to achieve a fixed switching frequency. Consequently, the phenomenon of flux and force ripples inherited from DTFC is improved. The experiment results are provided to validate the proposed control approach. Moreover, a recent work that is based on the optimal control is adopted as a comparison study. [ABSTRACT FROM AUTHOR]

Published
2019
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47. Design of Electronic Ballast for Short-Arc Xenon Lamp With Interleaved Half-Wave Rectifier.

Author

Chan, Shun-Yu, Yang, Tzu-Hung, and Chang, Yong-Nong

Subjects
HALF-wave rectifiers, ELECTRIC potential, XENON lamps, BALLASTS (Electricity), OPEN-circuit voltage, CAPACITORS
Abstract

This paper presents an interleaved half-wave rectifier circuit, which constitutes an electronic ballast with high open-voltage gain and current doubler. It is suitable for applications in short-arc xenon lamp needing high open-circuit voltage and low operating voltage. By integrating interleaved half-wave rectifier with LCC resonant circuit, the electronic ballast can provide a low arc-sustaining current dc power source with low ripple and dimmable capability along with starting current suppression feature. Finally, a 25-A 500-W short-arc xenon lamp electronic ballast is developed to possess full load efficiency as high as 91.32% along with dimming range falling between 7.6% and 100% and peak starting current being as low as 16 A. [ABSTRACT FROM AUTHOR]

Published
2016
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