Name: load matching in thevenin circuits
Uploaded: 2024-04-11T12:48:31.000Z
Duration: 1 min 16 s
Channel: JoVE

ביישומים מעשיים, מעגל מתוכנן לספק כוח מרבי ממקור לעומס.
מעגל שווה ערך לתבנין יכול לקבוע את ההספק המרבי שמעגל ליניארי יכול לספק.
הכוח המועבר הוא תוצר של התנגדות העומס וריבוע הזרם. זה משתנה כאשר התנגדות העומס משתנה.
כדי לזהות את ערך התנגדות העומס שממקסם את הכוח, נעשה שימוש בחשבון דיפרנציאלי. פישוט משוואה זו מספק את הערך האופטימלי של עמידות בעומס.
ערך התנגדות זה מוחלף לנגזרת השנייה של כוח, וכתוצאה מכך ערך שלילי, המאשר את התנאי להספק מרבי.
ערך ההתנגדות המתקבל מאפשר חישוב ההספק המרבי. אם התנגדות העומס אינה תואמת את התנגדות התבנין, הכוח המועבר בפועל יחרוג ממקסימום זה.
על פי משפט העברת הכוח המרבית, העברת הכוח הגבוהה ביותר מתרחשת כאשר התנגדות העומס תואמת את התנגדות תבנין.
שקול סוללה של פרמטרים ידועים, מחובר עם שני נגדים של ערכים ידועים. ההתנגדות התואמת את ההתנגדות הפנימית של הסוללה מקבלת את הכוח המרבי.

העברת כוח מקסימלית

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יישומים מעשיים רבים בתוך דיסציפלינות הנדסיות, כגון טלקומוניקציה, מחייבים אופטימיזציה של אספקת החשמל לעומס מחובר. מרדף זה, לעומת זאת, כרוך בהפסדים פנימיים אינהרנטיים, שיכולים להשתוות או לעלות על הכוח המסופק לעומס. המעגל המקביל של תבנין מועיל במציאת ההספק המרבי שמעגל ליניארי יכול לספק לעומס. ההנחה היא בהקשר זה שניתן להתאים את התנגדות העומס.

על ידי החלפת המעגל כולו עם המקבילה שלו לתבנין תוך שמירה על העומס כפי שמוצג בFigure 1,

<img alt="Figure1" src="/files/ftp_upload/15055/15055_PT_Figure_1.svg" style="text-align: center; height: 140px;"> Figure 1: מעגל המשמש להעברת כוח מקסימלית   הכוח הנמסר לעומס ניתן על ידי <img alt="Equation1" src="/files/ftp_upload/15055/15055_PT_Equation_1.svg" style="text-align: center; height: 40px;">.................(1) עבור מעגל נתון, ההתנגדות והמתח המקבילים של תבנין הם קבועים. השונות של הכוח הנמסר לעומס עם התנגדות העומס היא קטנה עבור ערכים קטנים או גדולים של התנגדות עומס, אך מקסימלית עבור התנגדות עומס כלשהי בין אפס לאינסוף. ההספק המרבי מתרחש כאשר התנגדות העומס שווה להתנגדות התבנין בביטוי כ- <img alt="Equation2" src="/files/ftp_upload/15055/15055_PT_Equation_2.svg" style="text-align: center; height: 14px;">.................(2) דבר זה ידוע כמשפט העברת הכוח המקסימלי. באמצעות משוואות 1 ו-2 מתקבל הביטוי להספק המרבי המועבר והוא מבוטא כ- <img alt="Equation3" src="/files/ftp_upload/15055/15055_PT_Equation_3.svg" style="text-align: center; height: 40px;">..................(3) משוואה זו חלה רק כאשר משוואה 2 תקפה, אחרת, ההספק הנמסר לעומס נקבע באמצעות Eq. 1.</div>

ביישומים מעשיים, מעגל מתוכנן לספק כוח מרבי ממקור לעומס.
מעגל שווה ערך לתבנין יכול לקבוע את המקסימום ...

Education

JoVE Core

Electrical Engineering

הנדסה חשמלית

Unit 1

יחידה 1

DC Circuit Analysis

ניתוח מעגלי DC

KEY TERMS AND CONCEPTS

מונחי מפתח ומושגים

Maximum Power Transfer

load matching in thevenin circuits

Load matching in Thevenin circuits helps a source deliver the most power to a connected load. This matters in engineering fields such as telecommunications, where power delivery must be optimized. Even then, internal losses can be significant and may equal or exceed the power sent to the load.

The Thevenin equivalent circuit is a useful way to study this situation. It replaces the full linear circuit with a simpler source and resistance while keeping the load in place. In this setup, the load resistance is assumed to be adjustable, so the power delivered to it can be tested across different values.

For a fixed circuit, the Thevenin equivalent voltage and resistance do not change. The load power changes only a little when the load resistance is very small or very large. It reaches a maximum at one value between zero and infinity.

The maximum power occurs when the load resistance equals the Thevenin resistance. This condition is called the maximum power transfer theorem. Using the load-power equation and this matching rule, the maximum transferred power can be found. If the matching condition is not met, the load power is determined from the general power equation instead.

Load Matching in Thevenin Circuits

nodal analysis

Using Node Voltages in Circuit Analysis

Nodal analysis uses node voltages to simplify circuit analysis. In this method, the voltage at each node becomes the main variable. Once those voltages are known, they can be used to find other values, such as the current through specific circuit parts. The process begins by choosing a reference node, also called a datum node. This node is selected for convenience and assigned a voltage of zero. The other nodes, called non-reference nodes, are then measured relative to that point. In the...

nodal analysis with voltage sources

Supernode Equations in Nodal Analysis

Nodal analysis uses node voltages and Kirchhoff’s laws to solve circuits with voltage sources. It is a systematic method for breaking a complex circuit into smaller parts that are easier to analyze. In this example, the circuit includes four resistors and two voltage sources. One voltage source is connected between a non-reference node and the reference node. In that case, the non-reference node voltage can be written directly as the source voltage. This removes one unknown and makes the...

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mesh analysis with current sources

Current Sources in Mesh Circuit Analysis

Current sources make mesh circuit analysis easier because they can reduce the number of equations needed. This applies to both independent and dependent current sources. The method depends on where the current source is placed in the circuit. When a current source appears in only one mesh, the setup is simple. Assign mesh currents as usual, but leave out the mesh that contains the current source from the equation process. Then apply Kirchhoff's voltage law, or KVL, to the remaining mesh to get...

source transformation

Circuit Source Equivalents

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Circuit Linearity and Resistor Behavior

Circuit linearity describes how a circuit responds when its input changes. A linear circuit has an output that is directly proportional to its input. This behavior follows two rules: homogeneity and additivity. Homogeneity means that if the input, or excitation, is multiplied by a constant factor, the response is multiplied by the same factor. For example, if the current is increased by a constant k, the voltage also increases by k times. Additivity means that the response to a sum of inputs...

superposition theorem

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

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...

norton's theorem

Norton Equivalent Circuit in DC Analysis

Norton equivalent circuit in DC analysis shows how a linear two-terminal circuit can be replaced by a simpler network. The replacement uses a current source, called I_N, in parallel with a resistor, called R_N. I_N is the short-circuit current through the terminals, and R_N is the input or equivalent resistance seen at the terminals when the independent sources are turned off. To find Norton's resistance, all independent sources in the circuit are set to zero. The resistance measured at the...

maximum power transfer

Load matching in Thevenin circuits helps a source deliver the most power to a connected load. This matters in engineering fields such as telecommunications, where power delivery must be optimized. Even then, internal losses can be significant and may equal or exceed the power sent to the load. The Thevenin equivalent circuit is a useful way to study this situation. It replaces the full linear circuit with a simpler source and resistance while keeping the load in place. In this setup, the load...

design example: strain gauge bridge or wheatstone bridge

design-example-strain-gauge-bridge-or-wheatstone-bridge

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key terms and concepts

Learn how Thevenin equivalent circuits predict maximum power transfer when load resistance matches Thevenin resistance in linear circuits.

Load Matching in Thevenin Circuits | 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

Load Matching in Thevenin Circuits

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