Name: finding voltage and impedance in circuit a
Uploaded: 2025-05-22T09:06:14.000Z
Duration: 1 min 18 s
Channel: JoVE

Le système de distribution d’énergie domestique, qui comprend les lignes de distribution et les transformateurs, peut être considéré comme le réseau source.
À l’intérieur de la maison, divers appareils électriques peuvent être représentés par des impédances de charge.
Le théorème de Thévenin simplifie ce système de distribution complexe en un circuit équivalent à Thévenin.
Trouver le circuit équivalent de Thévenin nécessite la connaissance de deux paramètres : la tension de Thévenin et l’impédance de Thévenin.
Pour comprendre le processus de leur détermination, considérons un circuit RLC simplifié connecté à une source de tension.
Pour calculer l’impédance de Thévenin, remplacez la source de tension par un court-circuit et déterminez l’impédance équivalente du circuit.
La tension de Thévenin est égale à la tension du circuit ouvert, équivalente à la chute de tension aux bornes de la branche parallèle du circuit.
Initialement, le courant circulant dans le maillage fermé du circuit est calculé. Ensuite, à l'aide de la loi d'Ohm, la chute de tension aux bornes de la branche parallèle est déterminée, ce qui donne la tension de Thévenin.
Si le circuit comporte des sources fonctionnant à des fréquences différentes, le circuit équivalent de Thévenin et les impédances du condensateur et de l’inductance doivent être déterminés séparément pour chaque fréquence.

circuits équivalents thévenin

Th&#233venin Equivalent Circuits

Le système de distribution d’électricité domestique, comprenant les lignes de distribution et les transformateurs, sert de réseau principal. Les appareils électriques d'un ménage peuvent être représentés par une impédance de charge. Pour simplifier ce système de distribution complexe, le théorème de Thévenin peut être appliqué pour créer un circuit équivalent de Thévenin. Si un circuit CA est divisé en deux parties (circuit A et circuit B), reliées par une seule paire de bornes comme indiqué sur la figure 1.

<img alt="Figure1" src="/files/ftp_upload/15113/15113_PT_Figure_1.svg" style="text-align: center; height: 140px;" />

Figure 1: Circuit divisé en deux parties

<img alt="Figure2" src="/files/ftp_upload/15113/15113_PT_Figure_2.svg" style="text-align: center; height: 150px;" />

Figure 2: Circuit A remplacé par son circuit équivalent Thévenin

Le remplacement du circuit A par son circuit équivalent Thévenin (une source de tension en série avec une impédance) ne modifie ni le courant ni la tension d'aucun élément du circuit B (illustré sur la figure 2). Les valeurs des courants et des tensions de tous les éléments du circuit B seront les mêmes, que le circuit B soit connecté au circuit A ou à son équivalent Thévenin. Deux paramètres sont nécessaires pour trouver le circuit équivalent de Thévenin : la tension de Thévenin et l'impédance de Thévenin. La figure 3 montre un circuit ouvert connecté aux bornes du circuit A pour déterminer la tension en circuit ouvert Voc, tandis que la figure 4 indique que l'impédance de Thévenin Zt  est l'impédance équivalente du circuit A*.

<img alt="Figure3" src="/files/ftp_upload/15113/15113_PT_Figure_3.svg" style="text-align: center; height: 96px;" />

Figure 3 : Circuit équivalent Thévenin avec Voc.

<img alt="Figure4" src="/files/ftp_upload/15113/15113_PT_Figure_4.svg" style="text-align: center; height: 96px;" />

Figure 4 : Circuit équivalent Thévenin montrant Zt...

Le circuit A* est formé à partir du circuit A en remplaçant toutes les sources de tension indépendantes par des courts-circuits et toutes les sources de courant indépendantes par des circuits ouverts. Généralement, l'impédance de Thévenin Zt  peut être déterminée en remplaçant à plusieurs reprises les impédances série ou parallèle par des impédances équivalentes.

Circuits équivalents Thévenin

Le système de distribution d’énergie domestique, qui comprend les lignes de distribution et les transformateurs, peut être considéré comme le réseau source.
À l’intérieur de la maison, ...

Education

Enseignement

JoVE Core

Electrical Engineering

Génie électrique

Unit 1

Unité 1

AC Circuit Analysis

Analyse des circuits CA

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

finding voltage and impedance in circuit a

The household power distribution system can be simplified with Thevenin's theorem. In this system, distribution lines and transformers form the main network. Electrical appliances can be treated as load impedance, which makes the circuit easier to analyze.

An AC circuit can be split into two parts, circuit A and circuit B, with a single pair of terminals between them. Circuit A can then be replaced by its Thevenin equivalent circuit. That equivalent has a voltage source in series with an impedance.

Replacing circuit A with its Thevenin equivalent does not change the current or voltage of any element in circuit B. The values in circuit B stay the same whether it is connected to the original circuit A or to the Thevenin equivalent. This is why the method is useful for studying connected circuits.

Two values are needed to build the Thevenin equivalent circuit. The first is the Thevenin voltage, which is found from the open-circuit voltage across the terminals of circuit A. The second is the Thevenin impedance, Zt, which is the equivalent impedance of circuit A*.

To form circuit A*, all independent voltage sources are replaced with short circuits. All independent current sources are replaced with open circuits. Then series or parallel impedances can be combined repeatedly to find Zt.

Finding Voltage and Impedance in Circuit A

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JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Finding Voltage and Impedance in Circuit A

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