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Electrical impedance

About: Electrical impedance is a research topic. Over the lifetime, 36015 publications have been published within this topic receiving 371891 citations. The topic is also known as: electrical impedance & complex impedance.


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Patent
13 Mar 1998
TL;DR: In this article, a power conversion circuit is proposed to drive a cold cathode fluorescent lamp (CCFL) while requiring minimal number of external components, including a controller, a direct drive network responsive to control inputs from the controller and coupled to receive a power signal, and a secondary network coupled to the CCFL.
Abstract: A power conversion circuit drives a cold cathode fluorescent lamp (CCFL) while requiring minimal number of external components. The circuit includes a controller, a direct drive network responsive to control inputs from the controller and coupled to receive a power signal, and a secondary network coupled to the CCFL. The direct drive network is low Q circuit comprising a plurality of switching transistors and a primary winding of a transformer such that an impedance of the direct drive network consists essentially of an inductance of the primary winding and capacitance of the direct drive network consists essentially of parasitic capacitance reflected from the secondary winding. The Q of the direct drive network is less than about 0.5 so that a square wave voltage signal is provided across the primary winding of the transformer. However, the inductance of the transformer is sufficiently high such that the voltage across a secondary winding of the transformer is sinusoidal. The secondary network comprises the secondary winding of the transformer coupled to the CCFL through a connector to provide a sinusoidal current to the CCFL. The controller controls the current passing through the CCFL by pulse width modulating the control inputs to the direct drive network.

114 citations

Journal ArticleDOI
TL;DR: An improved design of current controller, i.e., proportional–integral controller and capacitor-current-feedback active damping, is proposed to reduce the negative effect of PLL on current control and has a strong robustness against wide-range variation of grid impedance.
Abstract: For three-phase LCL -type grid-connected converter, when it is attached to weak grid, current control interacts with phase-locked loop (PLL) via point of common coupling voltage. Consequently, PLL dynamic might deteriorate grid current control and even result in system instability. However, the conventional design method of current controller neglects the impact of PLL, and therefore, it is hard for the current controller to mitigate the negative effect of PLL. In this paper, an improved design of current controller, i.e., proportional–integral controller and capacitor-current-feedback active damping, is proposed to reduce the negative effect of PLL on current control. First, a small-signal impedance model is developed to analyze the impact of PLL on current control. Then, the effect of current controller parameters on the converter output impedance is analyzed, and a design guideline to improve the current controller parameters is presented. With the improved parameters, in precondition of satisfying system stability margin under both stiff and weak grid, the negative effect of PLL on current control can be effectively mitigated without employing additional control strategies. Furthermore, the current control has a strong robustness against wide-range variation of grid impedance. Finally, the experiment demonstrates the effectiveness of the proposed design method.

114 citations

Journal ArticleDOI
TL;DR: In this article, the problem of a circular microstrip disk excited by a probe is solved using rigorous analysis using vector Hankel transforms, from which the unknown current can be solved for.
Abstract: The problem of a circular microstrip disk excited by a probe is solved using rigorous analysis. The disk is assumed to have zero thickness, and the current on the probe is taken to be uniform. Using vector Hankel transforms the problem is formulated in terms of vector dual-integral equations, from which the unknown current can be solved for. Due to the singular nature of the current distribution arising from probe excitation, the direct application of Galerkin's basis function expansion method gives a slowly convergent result. Therefore the singular part of the current is removed since the singularity is known a priori. The unknown current to be solved for is then regular and tenable to Galerkin's method of analysis. It is shown that this analysis agrees with the single-mode approximation when the dielectric substrate layer is thin, and that it deviates from the single-mode approximation when the substrate layer is thick. Excellent agreement of both the computed real and imaginary parts of the input impedance with experimental data is noted. The radiation patterns and the current distributions on the disk are also-presented.

114 citations

Patent
07 Feb 1996
TL;DR: In this paper, an output driver circuit is disclosed that generates an accurate and predictable output impedance driver value corresponding to a programmable external impedance, which includes an external resistance device, voltage comparator device, control logic, an evaluate circuit and off-chip driver (OCD) circuit.
Abstract: An output driver circuit is disclosed that generates an accurate and predictable output impedance driver value corresponding to a programmable external impedance. The output driver circuit includes an external resistance device, voltage comparator device, control logic, an evaluate circuit and off-chip driver (OCD) circuit. Voltage from the external resistance device (VZQ) is compared with voltage created from the evaluate circuit (VEVAL) by the voltage comparator device, which indicates to the control logic whether VEVAL is greater than or less than VZQ. The control logic will adjust the evaluate circuit accordingly with a count until the two voltages are basically equal (i.e., the count is alternating between two adjacent binary count values). At which time the control logic operates the OCD with the lower of the two adjacent count values to produce a proper and predictable driving impedance.

114 citations

Patent
24 Feb 2011
TL;DR: In this paper, a substrate processing apparatus includes high frequency power supply units 17a, 17b for outputting the high-frequency power of a predetermined frequency through the phase modulation, an opposing electrode 3 supporting a substrate, and a discharge electrode which is supplied with the highfrequency power output from the high voltage power supply unit side out of the plurality of matching circuits when supplying the high power.
Abstract: PROBLEM TO BE SOLVED: To uniformize the film thickness distribution, and to suppress the reflected power in a discharge electrode SOLUTION: A substrate processing apparatus includes high frequency power supply units 17a, 17b for outputting the high frequency power of the predetermined frequency through the phase modulation, an opposing electrode 3 supporting a substrate, a discharge electrode which is supplied with the high frequency power output from the high frequency power supply units to form plasma between the opposing electrode and itself by the high frequency power, a matching box 13 which has a plurality of matching circuits 20a-20d each of which being set to different impedance, and matches the impedance on the discharge electrode side to the impedance on the high frequency power supply unit side, and a selection means 22 for selecting a matching circuit in which the impedance on the discharge electrode side fluctuated by the phase modulation is matched with the impedance on the high frequency power supply unit side out of the plurality of matching circuits when supplying the high frequency power COPYRIGHT: (C)2011,JPO&INPIT

114 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20231,514
20223,479
20211,009
20201,579
20191,924
20181,809