A method to measure EMI due to electric field coupling on PCB

A new method to measure electric field coupling between PCB copper traces is presented. This method enables measurement of noise from waveforms obtainable from breadboard prototypes, which is available in an early stage in the design process. The measurement result can then be analyzed and provide information for further PCB design. This method is verified by experiments and applied to an off-line flyback converter.published_or_final_versio

A method to analysis and design for long life power converter

Engineers are always looking for more reliable or longer life power converters. Electrolytic capacitor is the critical component to be considered. Using the powerful calculation tools like Mathcad and Matlab and allowable life model, this paper aims at proposing a method to optimize the circuit design to lower the current ripple through the electrolytic capacitor in order to reach for longer capacitor life. Comparison between two modes of operation and the two converter topologies, Forward and Flyback, are made as well. This work provides a guideline to design power converters for long life application like LED driver. ©2010 IEEE.published_or_final_versionThe 25th Annual IEEE Applied Power Electronics Conference and Exposition (APEC 2010), Palm Springs, CA., 21-25 February 2010. In Proceedings of the 25th APEC, 2010, p. 1857-186

A life prediction scheme for electrolytic capacitors in power converters without current sensor

Predicting the expected life of switching power supply is essential since unexpected failure of the subsystem can produce enormous loss. Electrolytic capacitor is the weakest among various power components in a power converter. Monitoring the Equivalent Series Resistance (ESR) variation of the electrolytic capacitor, achieving by voltage and current ripple, can estimate the converter life. Currently, Hall Effect sensor or others are current sensing options but all of them add series impedance to the capacitor and deteriorate capacitor voltage waveform. A sensor-less current waveform prediction method is proposed. Popular current mode control with the switch current signal is used. Repetitive sampling on the switch current allows capacitors current waveforms prediction without any current sensor at capacitor nodes. Together with the voltage waveform acquired, the ESR value can be calculated. ©2010 IEEE.published_or_final_versionThe 25th Annual IEEE Applied Power Electronics Conference and Exposition (APEC 2010), Palm Springs, CA., 21-25 February 2010. In Proceedings of the 25th APEC, 2010, p. 973-97

Optimization methodology for efficient LLC resonant converter with power factor correction circuit

High efficiency is required in power conversion circuits. A systematic optimization procedure is presented in this paper to optimize LLC series resonant converter efficiency where the effect of LLC input voltage variation cased by power factor correction circuit is considered. A mode solver technique is proposed to handle LLC converter steady-state solutions under different input voltage conditions. Loss models are provided to calculate total component losses using the current and voltage information derived from the mode solver. A prototype 300W 12V output LLC converter is built using the optimization results. Experimental results are presented.postprintThe 6th IET International Conference on Power Electronics, Machines and Drives (PEMD 2012), University of Bristol, UK., 27-29 March 2012. In The I E T Conference Publication Series, 2012, Conference no. CP592, p. 1-

DC electrical distribution systems in bulidings

Author name used in this publication: Bryan PongVersion of RecordPublishe

Current driven synchronous rectifier with saturable current transformer and dynamic gate voltage control for LLC resonant converter

This paper proposes an improved current driven synchronous rectifier with saturable current transformer and dynamic gate voltage control feature for LLC resonant converter efficiency improvement. A model of saturable current transformer is proposed. Compared with other voltage driven and current-driven synchronous rectifier, this current driven synchronous rectifier has several outstanding characteristics. This synchronous rectifier is completely self-contained. It needs no external signal or power supply. It is also insensitive to parasitic inductance. Inherent dynamic gate voltage control reduces gate loss in the MOSFET by saturable current transformer. A 300W 400V-12V converter is built to demonstrate the advantages of the proposed current driven synchronous rectifier. High efficiency at 98% can be achieved. There is more than 4% efficiency improvement compared with schottky diode.published_or_final_versio

A constant-power battery charger with inherent soft switching and power factor correction

Author name used in this publication: Chi K. Tse2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A Constant-Power Battery Charger with Inherent Soft Switching and Power Factor Correction

A battery charging circuit, which operates as a constant power source, is proposed in this paper. By maintaining a constant output power throughout the charging process, the circuit reduces the size of thermal installation which would normally be required in the cases of constant-voltage or constant-current charging. The proposed circuit takes the form of a half-bridge converter with an additional small inductor and two extra diodes connected in parallel to two dividing capacitors. Constant power delivery is achieved by the discontinuous-voltage-mode operation of the two dividing capacitors, each of which is connected in parallel with a diode. The circuit enjoys low voltage and current stresses, and achieves soft switching with no extra components. When used off-line, the converter maintains a high input power factor and a low level of input current harmonic distortion that meets international regulations. All the above characteristics are determined only by the values of the circuit parameters, the control mechanism being noncritical. A 12 V 65 W prototype was built to demonstrate the merits of this circuit.published_or_final_versio

Practical solutions to the design of current-driven synchronous rectifier with energy recovery from current sensing

Current-driven synchronous rectifier with current sensing energy recovery has been proved to be suitable for almost all high frequency switching topologies. The synchronous rectifier can be driven on and off automatically according to the current direction. In fact it can be taken as an active diode with very low power dissipation. Some theoretical analysis and experimental results have been shown in the previous work. This paper presents an extended analysis to some practical considerations when applying this current-driven synchronous rectifier in switching converter design.published_or_final_versio

Low output ripple DC-DC converter based on an overlapping dual asymmetric half-bridge topology

Author name used in this publication: Chi K. Tse2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe