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

Der Theorin-Satz besagt, dass jede lineare Schaltung mit zwei Anschlüssen durch eine Ersatzschaltung mit einer einzigen Spannungsquelle in Reihe mit einem Widerstand ersetzt werden kann.
Wenn keine Last vorhanden ist, entspricht die Spannung an den offenen Klemmen der Thévenin-Spannung.
Um Thévenin-Resistenz zu finden, werden alle unabhängigen Quellen ausgeschaltet. Dann ist der Widerstand, der an den Terminals zu sehen ist, der Thévenin-Widerstand.
Enthält die Schaltung abhängige Quellen, werden die unabhängigen Quellen trotzdem abgeschaltet, aber an den Klemmen wird eine bekannte Testquelle angelegt.
Aus der resultierenden Anschlussspannung bzw. dem resultierenden Anschlussstrom kann der Thévenin-Widerstand bestimmt werden.
Schließlich wird die Last an den Ersatzkreis angeschlossen. Der Strom durch die Last wird anhand der Stromteilerformel berechnet. Mit Hilfe des Ohmschen Gesetzes wird die Thévenin-Spannung über der Last bestimmt.
Eine Batterie kann als Thévenin-Ersatzschaltung dargestellt werden. Die Thévenin-Spannung ist die Leerlaufspannung der Batterie und der Widerstand ist ihr Innenwiderstand.
Wenn man die Thévenin-Parameter kennt, ist es einfach, den Strom für verschiedene Lasten zu berechnen, ohne die gesamte Schaltung erneut untersuchen zu müssen.

thevinins theorem

Thévenins Theorem spielt eine entscheidende Rolle bei der Analyse elektrischer Schaltungen und bietet eine Lösung für die Herausforderungen, die durch variable Lasten innerhalb einer Schaltung entstehen. In der Praxis begegnet man häufig Schaltungen, bei denen bestimmte Elemente fest bleiben, während andere schwanken, oft als "Last" bezeichnet. Eine typische Haushaltssteckdose dient als ein hervorragendes Beispiel für eine variable Last, da sie mit einer Vielzahl von Geräten verbunden werden kann, jedes mit seinen eigenen einzigartigen elektrischen Eigenschaften. Jedes Mal, wenn ein neues Gerät eingesteckt oder entfernt wird, erfordert die gesamte Schaltung eine neue Analyse. Thévenins Theorem bietet eine Technik, die den festen Teil der Schaltung durch einen äquivalenten Schaltkreis ersetzt und dadurch die Analyse und das Design vereinfacht. Thévenins Theorem besagt, dass eine lineare Zweipol-Schaltung durch einen äquivalenten Schaltkreis dargestellt werden kann, der aus einer Spannungsquelle in Serie mit einem Widerstand besteht. Dieser äquivalente Schaltkreis kapselt effektiv das Verhalten der ursprünglichen Schaltung aus einer externen Perspektive ein. Zwei kritische Parameter definieren diesen Thévenin-äquivalenten Schaltkreis: die Thévenin-äquivalente Spannung (VTh), die der Leerlaufspannung an den Klemmen entspricht, und der Thévenin-äquivalente Widerstand (RTh), der den Eingangs- oder äquivalenten Widerstand an den Klemmen darstellt, wenn alle unabhängigen Quellen deaktiviert sind. Um das Konzept weiter zu veranschaulichen, betrachten Sie zwei Schaltungen, die in Figure 1 und Figure 2 gezeigt werden. Diese Schaltungen gelten als äquivalent, wenn sie die gleiche Spannungs-Strom-Beziehung an ihren Klemmen teilen. Wenn die Klemmen offen gelassen werden, was zu keinem Stromfluss führt, ist die Spannung über den offenen Klemmen die Thévenin-Spannung. Wenn alle unabhängigen Quellen ausgeschaltet sind, ist der Widerstand, der über die Klemmen gesehen wird, der Thévenin-Widerstand. <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;"> Um diese Idee praktisch anzuwenden und den Thévenin-Widerstand zu bestimmen, müssen wir zwei Szenarien berücksichtigen: FALL 1: In Situationen, in denen das Netzwerk keine abhängigen Quellen enthält, werden alle unabhängigen Quellen deaktiviert und der Eingangswiderstand ermittelt, d. h. der Widerstand zwischen den Anschlüssen a und b. FALL 2: Wenn das Netzwerk abhängige Quellen umfasst, deaktivieren Sie weiterhin alle unabhängigen Quellen. Vermeiden Sie jedoch die Deaktivierung abhängiger Quellen, da diese durch Schaltkreisvariablen gesteuert werden. Es ist erwähnenswert, dass der Wert des Thévenin-Widerstands (RTh) manchmal negativ sein kann, was bedeutet, dass der Stromkreis Strom liefert, anstatt ihn zu verbrauchen. Dieses Szenario ist in Schaltkreisen mit abhängigen Quellen möglich.

Thevinins Theorem

Der Satz von Thevenin besagt, dass jede lineare Schaltung mit zwei Anschlüssen durch eine Ersatzschaltung mit einer einzigen Spannungsquelle in Reihe mit einem ...

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Thevinin's Theorem

thevenin circuit equivalents

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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