Negative impedance converter

About: Negative impedance converter is a research topic. Over the lifetime, 5801 publications have been published within this topic receiving 87636 citations.

Passive underwater acoustic damping using shunted piezoelectric coatings

Abstract: In this technical note, the acoustic echo cancellations by a piezoelectric layer, coated to a rigid acoustic surface and shunted with various combinations of resistor, capacitor and inductor in series, have been investigated. A one-dimensional electro-acoustic model, enabling us to calculate the acoustic echo reduction for different shunting circuits, is established for the electrically shunted piezoelectric layer. It will be seen that shunting the piezoelectric layer with a resistor and an inductor can achieve good echo reduction only in a very narrow frequency bandwidth. In order to achieve broadband echo reduction, an inductor, a resistor and a capacitor in series shall be used. The formulae for calculating the inductance, resistance and capacitance of the shunting circuit have been derived. Numerical simulations show that the capacitance of the optimal shunting circuit can be negative for most commercial piezoelectric materials, although the inductance can be designed to be positive by adjusting the acoustic impedance of the piezoelectric materials. Realization of a capacitive circuit with negative capacitance has been proposed.

Multiple-phase DC-DC converter topology

Abstract: A multiple-phase DC—DC converter adds at least one additional phase to an N-phase DC—DC converter to improve the converter's response to changes in load. In one embodiment, an additional phase operates at a switching frequency greater than that of the N phases, to generate a current which is added to the N phase currents to improve the converter's response to changes in load. In another embodiment, an additional phase is configured to improve the converter's response to a load release. Here, the additional phase is kept off during load increase and steady-state conditions. However, when a load release occurs, the additional phase is turned on and acts to extract current from the converter's output terminal while the N phase currents slowly fall, to reduce the magnitude of output voltage overshoot that occurs on load release.

Per-Sequence Vector-Switching Matrix Converter Modules for Voltage Regulation

Abstract: This paper proposes a novel dynamic voltage restorer (DVR) topology based on reduced-order matrix converter modules. The topology utilizes two modules for selective and independent sequence voltage synthesis. As a result, the DVR proposed herein can compensate for balanced as well as unbalanced voltage sags/swells. Each module is realized using a vector-switching matrix converter. The entire topology is energy storage free, and each module is pulsewidth modulated using simple dc duty ratios. This paper provides details on the DVR modeling, equivalent circuit, and feedback controller design. Thorough computer simulations and experimental prototyping are used to validate the approach.

Small-signal analysis and design of weighted voltage-mode control for a multiple-output forward converter

Abstract: The small-signal model for a multiple-output forward power converter with weighted voltage control is derived. The effects of the weighting factors on the small-signal behavior are investigated. In addition, the small-signal characteristics of weighted voltage control are compared with the characteristics of a multiple-output power converter with coupled output-filter inductors. Finally, the effects of weighted voltage control on the small-signal characteristics of the converter with coupled inductors are examined. Based on the analysis, the design procedure for loop compensation is presented. The small-signal model and the design procedure are verified on an experimental two-output forward power converter. >