Ray-Lee Lin

Bio: Ray-Lee Lin is an academic researcher from National Cheng Kung University. The author has contributed to research in topics: Ballast & Inductor. The author has an hindex of 26, co-authored 121 publications receiving 2281 citations. Previous affiliations of Ray-Lee Lin include Tatung University & Chungshan Institute of Science and Technology.

A classification and evaluation of paralleling methods for power supply modules

Abstract: There is a fairly large number of methods for paralleling power converters. This paper classifies and examines these paralleling schemes, focusing on the active current-sharing approaches. Based on this classification, some new paralleling schemes can be achieved. Emphasis is placed on discussion and assessment of merits and limitations of these schemes. Finally, the prominent features of the dominant paralleling schemes are verified by simulation of a two-paralleled buck converter system.

Study and Implementation of a Current-Fed Full-Bridge Boost DC–DC Converter With Zero-Current Switching for High-Voltage Applications

Abstract: This paper presents a comprehensive study of a current-fed full-bridge boost dc-dc converter with zero-current switching (ZCS), based on the constant on-time control for high-voltage applications. The current-fed full-bridge boost converter can achieve ZCS by utilizing the leakage inductance and parasitic capacitance as the resonant tank. In order to achieve ZCS under a wide load range and with various input voltages, the turn-on time of the boost converter is kept constant, and the output voltage is regulated via frequency modulation. The steady-state analysis and the ZCS operation conditions under various load and input-voltage conditions are discussed. Finally, a laboratory prototype converter with a 22-27-V input voltage and 1-kV/1-kW output is implemented to verify the performance. The experimental results show that the converter can achieve high output voltage gains, and the highest efficiency of the converter is 92% at full-load condition with an input voltage of 27 V.

Simplified flux-linkage model for switched-reluctance motors

Abstract: A simplified and fast-built flux-linkage analytical model for the switched-reluctance motor is proposed, which utilises the Fourier series in expression of the current-dependent arc-tangent function. Presently, there are many conventional methods requiring numerous flux-linkage-current-position data; however, this is not economical for modelling. In the proposed model, the position dependency of the flux linkage is represented by a limited number of Fourier series terms, and the variation of the flux linkage with phase current is expressed by means of an arc-tangent function. The proposed model can be built with only five data points, which are simply obtained through finite-element analysis, for easy implementation and high computational efficiency. The accuracy of the model is verified via comparison with laboratory measurements of the machine steady-state voltage and current waveforms as well as several characteristic curves. The proposed model is shown to have a good degree of the accuracy.

An innovative technique for packaging power electronic building blocks using metal posts interconnected parallel plate structures

Abstract: Power electronics building blocks (PEBBs) are envisioned as integrated power modules consisting of power semiconductor devices, power integrated circuits, sensors, and protection circuits for a wide range of power electronics applications, such as inverters for motor drives and converters for power processing equipment. At the Center for Power Electronics Systems, we developed a topology for a basic building block-a two-switch two-diode half-bridge converter in totem-pole configuration with built-in gate-driver and protection circuitry, fiber-optic receiver/transmitter interface, and soft-switching capability. Based on the topology, a series of prototype modules, with 600 V, 3.3 kW rating, were fabricated using an innovative packaging technique developed for the program-metal posts interconnected parallel plate structure (MPIPPS). This new packaging technique uses direct attachment of bulk copper, not wire-bonding of fine aluminum wires, for interconnecting power devices. Electrical performance data of the packaged devices show that an air-cooled 15 kW inverter, operating from 400 V dc bus with 20 kHz switching frequency can be constructed by integrating three prototype modules, which is almost double what could be achieved with commercially packaged devices of the same rating.

Inductor-less piezoelectric transformer electronic ballast for linear fluorescent lamp

Abstract: This paper presents a cost-effective piezoelectric transformer based ballast circuit that is designed to drive a linear fluorescent lamp without dependence on any magnetic devices. This innovative circuit uses a radial vibration mode piezoelectric transformer or Transoner(R) to replace the inductor and the capacitors of the resonant tank portion in conventional electronic ballast circuits in order to effectively reduce the component number and cost. By fully utilizing the characteristics of the radial vibration mode piezoelectric transformer, the switches of the ballast circuit can work in a ZVS (zero-voltage switching) condition thus significantly reducing the turn-on switching losses when compared to a hard-switching topology. In addition, the inherent input capacitance of the radial vibration mode piezoelectric transformer enhances circuit operation by serving as a turn-off snubber for the half-bridge switches. This decreases turn-off voltage spiking thus reducing the turn-off losses for the half-bridge switches of the proposed circuit. Through these innovative circuit techniques, the proposed circuit provided 32-watts of power at commendable efficiency of around 90% when utilizing a standard 110-volt 60-Hz line as the power source and a 4-foot 40-watt linear fluorescent lamp as a load.

Light-emitting diodes

Abstract: Light-Emitting Diodes. (Monographs in Electrical and Electronic Engineering.) By A. A. Bergh and P. J. Dean. Pp. viii+591. (Clarendon: Oxford; Oxford University: London, 1976.) £22.

DC Microgrids—Part II: A Review of Power Architectures, Applications, and Standardization Issues

Abstract: DC microgrids (MGs) have been gaining a continually increasing interest over the past couple of years both in academia and industry. The advantages of dc distribution when compared to its ac counterpart are well known. The most important ones include higher reliability and efficiency, simpler control and natural interface with renewable energy sources, and electronic loads and energy storage systems. With rapid emergence of these components in modern power systems, the importance of dc in today's society is gradually being brought to a whole new level. A broad class of traditional dc distribution applications, such as traction, telecom, vehicular, and distributed power systems can be classified under dc MG framework and ongoing development, and expansion of the field is largely influenced by concepts used over there. This paper aims first to shed light on the practical design aspects of dc MG technology concerning typical power hardware topologies and their suitability for different emerging smart grid applications. Then, an overview of the state of the art in dc MG protection and grounding is provided. Owing to the fact that there is no zero-current crossing, an arc that appears upon breaking dc current cannot be extinguished naturally, making the protection of dc MGs a challenging problem. In relation with this, a comprehensive overview of protection schemes, which discusses both design of practical protective devices and their integration into overall protection systems, is provided. Closely coupled with protection, conflicting grounding objectives, e.g., minimization of stray current and common-mode voltage, are explained and several practical solutions are presented. Also, standardization efforts for dc systems are addressed. Finally, concluding remarks and important future research directions are pointed out.

Decentralized Control for Parallel Operation of Distributed Generation Inverters Using Resistive Output Impedance

Abstract: In this paper, a novel wireless load-sharing controller for islanding parallel inverters in an ac-distributed system is proposed This paper explores the resistive output impedance of the parallel-connected inverters in an island microgrid The control loops are devised and analyzed, taking into account the special nature of a low-voltage microgrid, in which the line impedance is mainly resistive and the distance between the inverters makes the control intercommunication between them difficult In contrast with the conventional droop-control method, the proposed controller uses resistive output impedance, and as a result, a different control law is obtained The controller is implemented by using a digital signal processor board, which only uses local measurements of the unit, thus increasing the modularity, reliability, and flexibility of the distributed system Experimental results are provided from two 6-kVA inverters connected in parallel, showing the features of the proposed wireless control

Decentralized control for parallel operation of distributed generation inverters using resistive output impedance

Abstract: In this paper, a novel wireless load-sharing controller for islanding parallel inverters in an ac distributed system is proposed. The paper explorers the resistive output impedance of the parallel-connected inverters in an island microgrid