scholarly journals High-frequency equivalent circuit of GaAs FETs for large-signal applications

1991 ◽  
Vol 39 (2) ◽  
pp. 224-229 ◽  
Author(s):  
M. Berroth ◽  
R. Bosch
2021 ◽  
Vol 11 (10) ◽  
pp. 4631
Author(s):  
Yu Chen ◽  
Xiaoqing Ji ◽  
Zhongyong Zhao

The accurate establishment of the equivalent circuit model of the synchronous machine windings’ broadband characteristics is the basis for the study of high-frequency machine problems, such as winding fault diagnosis and electromagnetic interference prediction. Therefore, this paper proposes a modeling method for synchronous machine winding based on broadband characteristics. Firstly, the single-phase high-frequency lumped parameter circuit model of synchronous machine winding is introduced, then the broadband characteristics of the port are analyzed by using the state space model, and then the equivalent circuit parameters are identified by using an optimization algorithm combined with the measured broadband impedance characteristics of port. Finally, experimental verification and comparison experiments are carried out on a 5-kW synchronous machine. The experimental results show that the proposed modeling method identifies the impedance curve of the circuit parameters with a high degree of agreement with the measured impedance curve, which indicates that the modeling method is feasible. In addition, the comparative experimental results show that, compared with the engineering exploratory calculation method, the proposed parameter identification method has stronger adaptability to the measured data and a certain robustness. Compared with the black box model, the parameters of the proposed model have a certain physical meaning, and the agreement with the actual impedance characteristic curve is higher than that of the black box model.


1990 ◽  
Vol 38 (4) ◽  
pp. 1019-1021 ◽  
Author(s):  
Tamotsu KOIZUMI ◽  
Masawa KAKEMI ◽  
Kazunori KATAYAMA ◽  
Hirohiko INADA ◽  
Kazuyoshi SUDEJI ◽  
...  

1977 ◽  
Vol 10 (4) ◽  
pp. 147-154 ◽  
Author(s):  
J. R. Tippetts

Specially designed 3-terminal elements called flow-junctions (FJs) and ‘reverse flow diverters' (RFDs) are shown to have useful amplifying properties which are often unrecognised. These are described by relating the devices to ideal network elements using an indefinite circle diagram. The FJ is useful between two transformer-like states and at the mid-point of this range its utility is described by its impedance matrix. A circuit using an RFD is shown to give a large-signal power gain which compares favourably with an equivalent circuit using a vortex device.


2021 ◽  
Vol 1 (1) ◽  
pp. 13-22
Author(s):  
Vasily S. LARIN ◽  
◽  
Daniil A. MATVEEV ◽  

To model high-frequency processes and determine the stresses on the internal insulation of transformer windings, reliable high-frequency models of power transformers are required. The accuracy of modeling high-frequency resonance processes in the windings depends on how correctly the model reproduces the natural frequencies and damping of free oscillations in the windings. To construct and verify high-frequency models of power transformers, it is necessary to have experimentally obtained data on the values of damping factors. There is a known method for determining the winding damping factors based on measurements of the voltage transfer functions at the internal points of the windings and their subsequent processing using the vector fitting technique, but its application is not always possible in practice. The article presents the results of theoretical studies performed for a simplified transformer winding equivalent circuit. It is shown that the damping factors can be estimated from the width of the resonance peaks of the frequency responses of the voltage modulus and reactive component at the midpoint of the equivalent circuit, and from the input admittance resistive component and current in the neutral of the considered resonance circuit.


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