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

在实际应用中，电路的设计旨在将最大功率从电源传输到负载。
戴维南等效电路可以确定线性电路能够提供的最大功率。
输出功率是负载电阻与电流平方的乘积。随着负载电阻的变化，输出功率也随之改变。
为了确定使功率最大化的负载电阻值，需使用微分学。简化该方程可得到最优的负载电阻值。
将该电阻值代入功率的二阶导数，得到一个负值，从而验证了最大功率的条件。
获得的电阻值可用于计算最大功率。如果负载电阻与戴维南电阻不匹配，则实际输出的功率将偏离该最大值。
根据最大功率传输定理，当负载电阻与戴维南电阻相等时，功率传输达到最大。
考虑一个参数已知的电池，其与两个阻值已知的电阻相连。当外接电阻等于电池内阻时，该电阻获得最大功率。

最大功率传输

工程学科（例如电信）中的许多实际应用都需要对连接负载的电力传输进行优化。然而，这种优化可能会带来固有的内部损耗，这些损耗可能会等于或超过所提供的负载功率。戴维南等效电路能够有助于确定线性电路向负载所提供的最大功率。在本文中假设负载电阻是可以调节的。 通过用戴维南等效电路来替换整个电路，同时保留其负载，如图1所示， <img alt="Figure1" src="/files/ftp_upload/15055/15055_PT_Figure_1.svg" style="text-align: center; height: 140px;"> 图1：用最大功率传输的电路  由下列公式计算出传递到负载的功率： <img alt="Equation1" src="/files/ftp_upload/15055/15055_PT_Equation_1.svg" style="text-align: center; height: 40px;">.................(1) 对于给定的电路，戴维南等效电阻值和电压值是固定的。对于较小或较大的负载电阻值，则传递到负载的功率会随着负载电阻值的变化较小，但对于零和无穷大之间的某些负载电阻，其变化是最大的。当负载电阻等于戴维南电阻时便会出现最大功率，并将其表示为： <img alt="Equation2" src="/files/ftp_upload/15055/15055_PT_Equation_2.svg" style="text-align: center; height: 14px;">.................(2) 这被称为最大功率传输定理。使用方程1和方程2能够推导出最大传输功率的表达式，并将其表示为： <img alt="Equation3" src="/files/ftp_upload/15055/15055_PT_Equation_3.svg" style="text-align: center; height: 40px;">..................(3) 该等式仅在等式2有效时适用，否则，传递至负载的功率由等式1来进行确定。

在实际应用中，电路的设计旨在将最大功率从电源传输至负载。  
戴维南等效电路可用于确定最大……

Education

教育

JoVE Core

Electrical Engineering

电气工程

Unit 1

第一单元

DC Circuit Analysis

直流电路分析

KEY TERMS AND CONCEPTS

关键术语与概念

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

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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...

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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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