Name: thevenin circuit equivalents
Uploaded: 2024-04-11T12:48:31.000Z
Duration: 1 min 15 s
Channel: JoVE

Le théorème de Thevenin stipule que tout circuit linéaire à deux bornes peut être remplacé par un circuit équivalent avec une seule source de tension en série avec une résistance.
En l’absence de charge, la tension aux bornes ouvertes sera la tension de Thévenin.
Pour trouver la résistance de Thévenin, toutes les sources indépendantes sont désactivées. Ensuite, la résistance observée aux bornes est la résistance de Thévenin.
Si le circuit contient des sources dépendantes, les sources indépendantes sont toujours désactivées, mais une source de test connue est appliquée aux bornes.
À partir de la tension ou du courant aux bornes résultant, la résistance de Thévenin peut être déterminée.
Enfin, la charge est connectée au circuit équivalent. Le courant traversant la charge est calculé à l’aide de la formule du diviseur de courant. À l'aide de la loi d'Ohm, la tension de Thévenin aux bornes de la charge est déterminée.
Une batterie peut être représentée comme le circuit équivalent de Thévenin. La tension de Thévenin est la tension en circuit ouvert de la batterie et la résistance est sa résistance interne.
Connaissant les paramètres de Thévenin, il est facile de calculer le courant pour diverses charges sans réexaminer l’ensemble du circuit.

théorème de thévinin

Le théorème de Thévenin joue un rôle central dans l'analyse des circuits électriques, offrant une solution aux défis posés par les charges variables dans un circuit. Dans les applications pratiques, il est courant de rencontrer des circuits dans lesquels certains éléments restent fixes tandis que d'autres fluctuent, souvent appelés « charge ». Une prise électrique domestique typique constitue un excellent exemple de charge variable, car elle peut être connectée à une variété d’appareils, chacun ayant ses propres caractéristiques électriques. Chaque fois qu’un nouvel appareil est branché ou retiré, l’ensemble du circuit nécessite une nouvelle analyse. Le théorème de Thévenin propose une technique qui remplace la partie fixe du circuit par un circuit équivalent, simplifiant ainsi l'analyse et la conception. Le théorème de Thévenin stipule qu'un circuit linéaire à deux bornes peut être représenté par un circuit équivalent constitué d'une source de tension en série avec une résistance. Ce circuit équivalent résume efficacement le comportement du circuit d’origine d’un point de vue externe. Deux paramètres critiques définissent ce circuit équivalent de Thévenin : la tension équivalente de Thévenin (VTh), qui correspond à la tension en circuit ouvert aux bornes, et la résistance équivalente de Thévenin (RTh), qui représente la résistance d'entrée ou équivalente aux bornes lorsque tous les sources indépendantes sont désactivées. Pour illustrer davantage le concept, considérons deux circuits illustrés aux figures 1 et 2. Ces circuits sont considérés comme équivalents lorsqu'ils partagent la même relation tension-courant à leurs bornes. Lorsque les bornes sont laissées en circuit ouvert, ce qui entraîne aucun flux de courant, la tension aux bornes ouvertes sera la tension de Thévenin. Lorsque toutes les sources indépendantes sont éteintes. Alors la résistance vue aux bornes est la résistance Thévenin. <img alt="Figure1" src="/files/ftp_upload/15053/15053_PT_Figure_1.svg" style="text-align: center; height: 128px;"> Figure 1 <img alt="Equation1" src="/files/ftp_upload/15053/15053_PT_Equation_1.svg" style="text-align: center; height: 14px;"> <img alt="Figure2" src="/files/ftp_upload/15053/15053_PT_Figure_2.svg" style="text-align: center; height: 128px;"> Figure 2 <img alt="Equation2" src="/files/ftp_upload/15053/15053_PT_Equation_2.svg" style="text-align: center; height: 14px;"> Pour appliquer pratiquement cette idée et déterminer la résistance de Thévenin, il faut considérer deux scénarios: CAS 1 : Dans les situations où le réseau ne contient aucune source dépendante, toutes les sources indépendantes sont désactivées et la résistance d'entrée est vérifiée, qui est la résistance vue entre les bornes a et b. CAS 2 : Lorsque le réseau intègre des sources dépendantes, continuez à désactiver toutes les sources indépendantes. Cependant, évitez de désactiver les sources dépendantes car elles sont contrôlées par des variables du circuit. Il est à noter que la valeur de la résistance Thévenin (RTh) peut parfois être négative, signifiant que le circuit fournit de l'énergie plutôt que de la consommer. Ce scénario est réalisable dans les circuits à sources dépendantes.

Théorème de Thévinin

Le théorème de Thevenin stipule que tout circuit linéaire à deux bornes peut être remplacé par un circuit équivalent avec une seule source de tension en série avec un ...

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DC Circuit Analysis

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Thevinin's Theorem

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Thevenin circuit equivalents simplify linear two-terminal circuits by replacing the fixed part of a network with one equivalent source and one resistor. This method is useful when a circuit has a fixed section and a load that can change. A household electrical outlet is a familiar example, because different appliances can be plugged in or removed. Each change in load can require a new circuit analysis, so an equivalent circuit makes the work easier.

Thevenin's theorem states that a linear two-terminal circuit can be represented by a voltage source in series with a resistor. From the outside, this equivalent circuit has the same behavior as the original network. Two circuits are considered equivalent when they have the same voltage-current relationship at their terminals. The Thevenin equivalent voltage, VTh, is the open-circuit voltage at the terminals, and the Thevenin equivalent resistance, RTh, is the input resistance seen at the terminals when the independent sources are turned off.

To find the Thevenin resistance, the method depends on the kind of sources in the network. If the circuit has no dependent sources, all independent sources are deactivated and the resistance between terminals a and b is found. If the network includes dependent sources, the independent sources are still turned off, but the dependent sources stay active because they are controlled by circuit variables. In some cases, RTh can be negative. That means the circuit is supplying power instead of consuming it, which can happen in circuits with dependent sources.

Thevenin Circuit Equivalents

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Thevenin circuit equivalents simplify linear two-terminal circuits by replacing the fixed part of a network with one equivalent source and one resistor. This method is useful when a circuit has a fixed section and a load that can change. A household electrical outlet is a familiar example, because different appliances can be plugged in or removed. Each change in load can require a new circuit analysis, so an equivalent circuit makes the work easier. Thevenin's theorem states that a linear...

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key terms and concepts

Learn how Thevenin’s theorem replaces a linear two-terminal circuit with a voltage source and resistor, and how to find VTh and RTh in circuit analysis.

Thevenin Circuit Equivalents | JoVE K12

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

Thevenin Circuit Equivalents

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