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

تنص نظرية Thevenin على أنه يمكن استبدال أي دائرة خطية ثنائية الطرفين بدائرة مكافئة بمصدر جهد واحد في سلسلة مع مقضوم.
في حالة عدم وجود حمل ، سيكون الجهد عبر المحطات المفتوحة هو جهد Thévenin.
للعثور على مقاومة Thévenin ، يتم إيقاف تشغيل جميع المصادر المستقلة. ثم المقاومة التي تظهر عبر المحطات هي مقاومة Thévenin.
إذا كانت الدائرة تحتوي على مصادر تابعة ، فلا تزال المصادر المستقلة متوقفة عن العمل ، ولكن يتم تطبيق مصدر اختبار معروف في المطاريف.
من الجهد الطرفي الناتج أو التيار ، يمكن تحديد مقاومة Thévenin.
أخيرا ، يتم توصيل الحمل بالدائرة المكافئة. يتم حساب التيار عبر الحمل باستخدام صيغة المقسم الحالية. باستخدام قانون أوم ، يتم تحديد جهد Thévenin عبر الحمل.
يمكن تمثيل البطارية على أنها الدائرة المكافئة ل Thévenin. جهد Thévenin هو جهد الدائرة المفتوحة للبطارية والمقاومة هي مقاومتها الداخلية.
بمعرفة معلمات Thévenin ، من السهل حساب التيار للأحمال المختلفة دون إعادة فحص الدائرة بأكملها.

نظرية ثيفينين

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تلعب نظرية ثيفين دورًا محوريًا في تحليل الدوائر الكهربائية، حيث تقدم حلاً للتحديات التي تفرضها الأحمال المتغيرة داخل الدائرة. في التطبيقات العملية، من الشائع أن تواجه دوائر حيث تظل بعض العناصر ثابتة بينما تتقلب عناصر أخرى، وغالبًا ما يشار إليها باسم "الحمل". يعد مأخذ التيار الكهربائي المنزلي النموذجي بمثابة مثال رئيسي على الحمل المتغير، حيث يمكن توصيله بمجموعة متنوعة من الأجهزة، ولكل منها خصائصها الكهربائية الفريدة. في كل مرة يتم فيها توصيل جهاز جديد أو إزالته، تتطلب الدائرة بأكملها تحليلًا جديدًا. توفر نظرية ثيفين تقنية تستبدل الجزء الثابت من الدائرة بدائرة مكافئة، وبالتالي تبسيط التحليل والتصميم. تنص نظرية ثيفين على أنه يمكن تمثيل الدائرة الخطية ذات الطرفين بدائرة مكافئة تتكون من مصدر جهد موصول على التوالي مع مقاومة. تقوم هذه الدائرة المكافئة بتغليف سلوك الدائرة الأصلية بشكل فعال من منظور خارجي. تحدد معلمتان حاسمتان هذه الدائرة المكافئة لـ Thévenin: الجهد المكافئ لـ Thévenin (VTh)، والذي يتوافق مع جهد الدائرة المفتوحة عند الأطراف، والمقاومة المكافئة لـ Thévenin (RTh)، والتي تمثل المدخلات أو المقاومة المكافئة في المحطات الطرفية عندما تكون جميعها تم تعطيل المصادر المستقلة. لتوضيح المفهوم بشكل أكبر، فكر في دائرتين موضحتين في الشكل 1 والشكل 2. تعتبر هذه الدوائر متكافئة عندما تشترك في نفس العلاقة بين الجهد والتيار عند أطرافها. عندما تُترك الأطراف مفتوحة، مما يؤدي إلى عدم تدفق التيار، فإن الجهد عبر الأطراف المفتوحة سيكون جهد ثيفينين. عندما يتم إيقاف تشغيل جميع المصادر المستقلة. ثم المقاومة التي تظهر عبر المحطات هي مقاومة ثيفينين. <img alt="Figure1" src="/files/ftp_upload/15053/15053_PT_Figure_1.svg" style="text-align: center; height: 128px;"> الشكل 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;"> الشكل 2 <img alt="Equation2" src="/files/ftp_upload/15053/15053_PT_Equation_2.svg" style="text-align: center; height: 14px;">
لتطبيق هذه الفكرة عمليا وتحديد مقاومة ثيفينين، لا بد من النظر في سيناريوهين: الحالة 1: في الحالات التي لا تحتوي فيها الشبكة على مصادر تابعة، يتم إلغاء تنشيط جميع المصادر المستقلة ويتم التأكد من مقاومة الإدخال، وهي المقاومة المرئية بين الطرفين a وb
الحالة 2: عندما تتضمن الشبكة مصادر تابعة، استمر في إلغاء تنشيط كافة المصادر المستقلة. ومع ذلك، امتنع عن إلغاء تنشيط المصادر التابعة حيث يتم التحكم فيها بواسطة متغيرات الدائرة
تجدر الإشارة إلى أن قيمة مقاومة ثيفينين (RTh) يمكن أن تكون في بعض الأحيان سالبة، مما يدل على أن الدائرة تزود الطاقة بدلاً من استهلاكها. هذا السيناريو ممكن في الدوائر ذات المصادر التابعة.
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تنص نظرية Thevenin على أنه يمكن استبدال أي دائرة خطية ثنائية الطرفين بدائرة مكافئة بمصدر جهد واحد في سلسلة مع ...

Education

JoVE Core

Electrical Engineering

الهندسة الكهربائية

Unit 1

الوحدة الأولى

DC Circuit Analysis

تحليل دوائر التيار المستمر

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

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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Current Sources in Mesh Circuit Analysis

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Circuit Source Equivalents

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Circuit Linearity and Resistor Behavior

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Analyzing Circuits with Superposition

Superposition is a circuit analysis method for linear circuits with more than one independent source. It lets you find the voltage across or current through an element by adding the separate effects of each source acting alone. To use superposition, keep one independent source active and turn off the others. A voltage source is replaced by a short circuit, and a current source is replaced by an open circuit. Then calculate the output from the single active source. Repeat the process for each...

thevinin's theorem

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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Norton Equivalent Circuit in DC Analysis

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Load Matching in Thevenin Circuits

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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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