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Soft Switching Boost Converter with a Flyback Snubber for High Power Applications
No full text[[abstract]]This paper presents a soft-switching boost converter with a flyback snubber for high power applications. The proposed converter configuration can achieve both near zero-voltage and zero-current soft-switching features, while it can reduce the current and voltage stresses of the main switch. In this paper, several passive and active snubbers associated with boost converters are first reviewed, and their limitations are then addressed. One of the boost converters with a flyback snubber is proposed and analyzed in detail to explain the discussed features. Experimental results obtained from a 5-kW boost converter have confirmed that the proposed converter configuration is attractive and feasible for high power applications.[[fileno]]2030197010005[[department]]電機工程學
Analysis and Implementation of and Improved Current-Doubler Rectifier with Coupled Inductors
No full text[[abstract]]In this paper, an improved current-doubler rectifier with coupled inductors is proposed. The proposed rectifier can extend duty ratio to reduce the peak current through the isolation transformer winding and lower output current ripple as well as voltage stress of the rectifier diodes. In this study, a 500-W prototype with a full-bridge phase-shift converter, the proposed rectifier, with input voltage of 400 V and output voltage of 12 V was built. Theoretical analysis and experimental results have verified that the proposed rectifier is attractive for high step-clown voltage and high-power applications.[[fileno]]2030197010010[[department]]電機工程學
Sequential Color LED Backlight Driving System for LCD Panels
No full text[[abstract]]In this paper, a sequential color light emitting diode (LED) backlight driving system for liquid crystal display (LCD) panels is proposed. Due to improvement on luminous efficacy, long life and wide color gamut, LED has gradually substituted for cold cathode fluorescent lamp as backlight. The proposed driving system adopts sequential color scanning scheme to improve light utilization efficiency by removing color filter. To meet display performance requirement that chromaticity variation Delta uv needs to be limited below 0.002, this paper also proposes a family of output current ripple free topologies to control the average driving current precisely, which in turn can reduce chromaticity variation. In addition, an LED bypass circuit is proposed to prevent LED arrays from open-circuit, and a driving voltage resetter is introduced to eliminate current spikes, improving backlight reliability and availability significantly. A forward-type output current ripple free converter has been built to sequentially drive color LED arrays, from which experimental measurements have verified the discussed performance and feasibility of the proposed system.[[fileno]]2030197010021[[department]]電機工程學
A Systematic Approach to Developing Single-Stage Soft Switching PWM Converters
No full text[[abstract]]A systematic approach to developing soft switching PWM converters based on the synchronous switch scheme is presented in this paper. With the approach, several families of passive and active soft switching PWM converters, such as buck-boost, Zeta, Cuk, and Sepic, can be generated from the two basic converters , buck and boost. Also, the approach is used to integrate multiple converters to form a single-stage soft switching PWM converter. It has been shown that analysis of the converters can be conveniently performed from the derived general configurations, reducing the complexity significantly. Therefore, employing the technique can not only explore more physical insights into the converters in a family but reveal more relationships among the soft switching converters over conventional approaches. Measured results from a prototype have verified the feasibility of the derived single-stage converters.[[fileno]]2030197010053[[department]]電機工程學
A Microprocessor Based Toggle-Control Lighting System
No full text[[abstract]]Analysis, design, practical consideration, and implementation of a microprocessor-based toggle-control lighting system are presented. The system is primarily configured with a power factor corrector (PFC), a square-wave voltage generator, a manually controlled toggle switch, and two relays. Toggling the toggle switch can select a different number of lamps in operation, resulting in a mutual dimming feature. A lighting system with this specific ballast gains the merits of lower system cost and more flexibilities in lighting fixture design, as compared to conventional systems.[[fileno]]2030197010084[[department]]電機工程學
具高功因、可調光之Boost 及半橋SRC 接枝電子安定器
No full text[[abstract]]在電力轉換器中，除了本體功能外，為達到降低線上諧波電流的污染及電磁波干 擾（ EMI ），傳統上串接一級功因改善電路， 使得輸入電壓與電流均為弦波且同相，雖然 達到了目的，但卻增加了系統的成本、體積及控制的複雜度。本文利用植物接枝法〔１〕， 合併開關元件，衍生出高功因〔２〕、可調光之 Boost 與半橋 SRC 接枝電子安定器。經由 電腦模擬的結果與硬體電路的驗證，證實電路理論的推導與分析是正確的，有其實用價值。 對於小功率，又需功因校正的電子安定器，更適合使用植物接枝法，合併開關元件，而不需 提高開關元件的耐壓及耐流。[[fileno]]2030197010096[[department]]電機工程學
Current Distribution Control Schemes for Parallel Connected Converter Modules Part II: Central-Limit Control
No full text[[abstract]]In the central-limit control (CLC), the multiloop controls are employed to regulate the output voltage and track the central weighted current, thus equalizing the output current of each converter module (CM). The current distribution error (CDE) between the output current of each CM is used as a criterion in judging system performance. The prediction and simulation results of this control scheme are illustrated. Furthermore, when incorporated with the maximum current limit, the proposed control method can determine the number of required converters in the active state for each load condition. As the result, the efficiency or a system can be increased significantly. A comparison between the performances of a system under master-slave control (MSC) and CLC is given.[[fileno]]2030197010099[[department]]電機工程學
Speeding up emulation based diagnosis techniques for logic cores
No full text[[abstract]]This article proposes a new approach for an FPGA-based emulation system for IC fault diagnosis that incorporates three speedup techniques: circuit partitioning, fault-injection elements (using a novel design), and a fault-injection scan chain. Experimental results in terms of hardware overhead and emulation time for ISCAS-85 benchmark circuits are compared with previous works to highlight the 33× speedup and 44% reduced overhead of this proposed system.[[fileno]]2030108010096[[department]]電機工程學
Silicon-nanocrystal resonantcavity light emitting devices for color tailoring
Get PDF[[abstract]]A silicon-nanocrsytal resonant-cavity light-emitting device (RCLED) is presented. The microcavity, made by a silicon nanocrystal layer inserted between a semitransparent Au reflector and a distributed Bragg reflector mirror, shows enhanced emission intensity by four times at resonance wavelength and 1/8 narrow emission spectrum compared to nonresonant devices. The external quantum efficiency and power conversion efficiency also increase by 3.5 times. Multiple colors, green, green-yellow, orange, and red are displayed by adjusting the cavity length of RCLED.[[fileno]]2030180010025[[department]]電機工程學
Very strong coupling in GaAs based optical microcavities
Get PDF[[abstract]]We show that when following a simple cavity design metric, a quantum well exciton-microcavity photon coupling constant can be larger than the exciton binding energy in GaAs based optical microcavities. Such a very strong coupling significantly reduces the relative electron-hole motion and makes the polaritons robust against phonon collisions. The corresponding polariton dissociation and saturation boundaries on the phase diagram are much improved, and our calculations suggest the possibility of constructing a room temperature, high power exciton-polariton laser without resorting to wide bandgap semiconductors.[[fileno]]2030192010003[[department]]電機工程學