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

O teorema de Thevenin afirma que qualquer circuito linear de dois terminais pode ser substituído por um circuito equivalente com uma única fonte de tensão em série com um resistor.
Na ausência de carga, a tensão nos terminais abertos será a tensão de Thévenin.
Para encontrar resistência a Thévenin, todas as fontes independentes são desligadas. Então, a resistência vista através dos terminais é a resistência de Thévenin.
Se o circuito contiver fontes dependentes, as fontes independentes ainda serão desligadas, mas uma fonte de teste conhecida será aplicada nos terminais.
A partir da tensão ou corrente terminal resultante, a resistência de Thévenin pode ser determinada.
Finalmente, a carga é conectada ao circuito equivalente. A corrente através da carga é calculada usando a fórmula do divisor de corrente. Usando a Lei de Ohm, a tensão de Thévenin através da carga é determinada.
Uma bateria pode ser representada como o circuito equivalente de Thévenin. A tensão de Thévenin é a tensão de circuito aberto da bateria e a resistência é sua resistência interna.
Conhecendo os parâmetros de Thévenin, é fácil calcular a corrente para várias cargas sem reexaminar todo o circuito.

teorema de thévenin

O teorema de Thévenin desempenha um papel fundamental na análise de circuitos elétricos, oferecendo uma solução para os desafios colocados por cargas variáveis ​​dentro de um circuito. Em aplicações práticas, é comum encontrar circuitos onde certos elementos permanecem fixos enquanto outros flutuam, muitas vezes chamados de “carga”. Uma tomada elétrica doméstica típica serve como um excelente exemplo de carga variável, pois pode ser conectada a uma variedade de aparelhos, cada um com suas características elétricas exclusivas. Cada vez que um novo aparelho é conectado ou removido, todo o circuito requer uma nova análise. O teorema de Thévenin fornece uma técnica que substitui a parte fixa do circuito por um circuito equivalente, simplificando assim a análise e o projeto.

O teorema de Thévenin afirma que um circuito linear de dois terminais pode ser representado por um circuito equivalente constituído por uma fonte de tensão em série com um resistor. Este circuito equivalente encapsula efetivamente o comportamento do circuito original de uma perspectiva externa. Dois parâmetros críticos definem este circuito equivalente de Thévenin: a tensão equivalente de Thévenin (VTh), que corresponde à tensão de circuito aberto nos terminais, e a resistência equivalente de Thévenin (RTh), que representa a entrada ou resistência equivalente nos terminais quando todas as fontes independentes são desativadas.

Para ilustrar o conceito de forma mais detalhada, considere dois circuitos mostrados na Figura 1 e na Figura 2. Esses circuitos são considerados equivalentes quando compartilham a mesma relação tensão-corrente em seus terminais. Quando os terminais são deixados em circuito aberto, resultando em ausência de fluxo de corrente, a tensão nos terminais abertos será a tensão de Thévenin. Quando todas as fontes independentes são desativadas, a resistência vista nos terminais é a resistência de 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;" />

Para aplicar essa ideia na prática e determinar a resistência de Thévenin, devemos considerar dois cenários:

CASO 1: Nas situações em que a rede não contém fontes dependentes, todas as fontes independentes são desativadas e é verificada a resistência de entrada, que é a resistência observada entre os terminais a e b.

CASO 2: Quando a rede incorpora fontes dependentes, continuar desativando todas as fontes independentes. No entanto, evite desativar fontes dependentes, pois elas são controladas por variáveis ​​de circuito.

É importante notar que o valor da resistência de Thévenin (RTh) às vezes pode ser negativo, significando que o circuito está fornecendo energia em vez de consumi-la. Este cenário é viável em circuitos com fontes dependentes.

Teorema de Thévenin

O teorema de Thevenin afirma que qualquer circuito linear de dois terminais pode ser substituído por um circuito equivalente com uma única fonte de tensão em série com um ...

Education

JoVE Core

Electrical Engineering

Engenharia Elétrica

Unit 1

Unidade 1

DC Circuit Analysis

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KEY TERMS AND CONCEPTS

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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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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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