Computer aided design of a crossing current resonant converter (XCRC)

Computer aided design of the new Crossing Current Resonant Converter (XCRC) is introduced. The XCRC enables zero voltage switching without excessive voltage and current stresses. This makes the converter operate with minimum dissipation. A systematic way of computer aided design of the XCRC is also introduced. Spreadsheet programme incorporates circuit equations for calculation of component values. These values are then used for circuit simulation which further probes into the waveforms before the hardware is actually built. Finally the circuit is built and experimental results are included.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

Least coupling paths model for non-contact EMI base on lump element approach in switch mode converter

A simplified physical model concludes a minimum of six equivalent physical coupling paths, Least Coupling Paths (LCP), using lump elements approach through non-contact EMI coupling mechanism to the terminals of LISN. Simulation shows both inductive and capacitive coupling through each path may produce substantial EMI measured by a LISN. This physical model is good for understanding, diagnosis and emission estimation.published_or_final_versio

Common-Mode Noise Cancellation in Switching-Mode Power Supplies Using an Equipotential Transformer Modeling Technique

Electromagnetic interference (EMI) is a significant challenge in the design of high-efficiency switching-mode power supplies due to the presence of common-mode (CM) noise. In many power-supply designs, a variety of noise suppression schemes must be implemented in order to meet EMI requirements. Most of these schemes create power loss that lead to efficiency and thermal issues. In this paper, a transformer construction technique is proposed that effectively reduces the CM noise current injecting across the isolated primary and secondary windings. This technique is based on the zero equipotential line theory. A transformer design with the proposed CM noise cancellation technique can achieve high conversion efficiency as well as substantial CM noise rejection.published_or_final_versio

Essential-coupling-path models for non-contact EMI in switching power converters using lumped circuit elements

This paper proposes a simple lumped circuit modeling approach for describing noncontact EMI coupling mechanisms in switching power converters. The resulting model assumes a minimum number of noise sources and contains essential coupling paths that allow easy physical interpretations. Essentially, all capacitive couplings are represented by an equivalent noise voltage source and six coupling impedances, whereas all inductive couplings are represented by an equivalent noise current source and three coupling impedances. The resulting coupled noise appears as currents flowing into the terminals of the Line-Impedance-Stabilization-Network (LISN). The equivalent voltage source can be conveniently approximated as the switching-node-to-zero voltage, which is typically a rectangular pulse of a few hundred volts. The equivalent current source can be modeled as the current flowing around a loop containing the equivalent voltage source and parasitics such as winding capacitance of the power transformer, the snubber capacitance and connection inductances. Also, the coupling impedances can be estimated by making simplifying assumptions about the geometry of the components and tracks, or by direct measurements. Simulations and experiments verify how inductive and capacitive couplings through each path may produce substantial EMI measured by the LISN. Being based on a lumped circuit approach, the proposed model is easy to apply in practice for understanding, diagnosing and approximating EMI behaviors.published_or_final_versio

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

A new converter topology is described for applications requiring very low output current ripple. The proposed converter consists of two asymmetric half-bridge converters whose output voltages overlap in a finite interval of time. This converter provides well regulated and smooth dc output without the need of an output filter. The output voltage is regulated by direct amplitude modulation. Unlike the standard interleaved converters, the proposed converter is robust to input voltage and operating duty cycle variations. Furthermore, equal current sharing is automatically achieved under all conditions, thus ensuring full utilisation of the output rectifiers for wide input and output ranges. The circuit achieves zero-voltage turnon for all primary switches and zero-current turnoff for the output rectifiers. An isolated dc-dc converter prototype with 5-V output voltage and 20-A output current has been built to verify the design. © 2007 IEEE.published_or_final_versio

Techniques for input ripple current cancellation : classification and implementation

Author name used in this publication: J. C. P. LiuAuthor name used in this publication: C. K. TseAuthor name used in this publication: M. H. Pong2000-2001 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Essential-coupling-path models for non-contact EMI in switching power converters using lumped circuit elements

Author name used in this publication: Chi K. TseAuthor name used in this publication: C. P. Liu2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

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