lecture 6: thevenin and norton equivalents, maximum power transfer, & superposition nilsson...

1

Lecture 6:Thevenin and Norton Equivalents,Maximum Power Transfer, &SuperpositionNilsson & Riedel 4.10-4.13

ENG17 (Sec. 2): Circuits I

Spring 2014

April 17, 2014

2

Overview

• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power

Transfer• Superposition

3

Thevenin Equivalent Circuit

• Independent voltage source in series with resistor• Provides simplified equivalence to more complex circuit

4

Finding Thevenin Equivalent

5

Overview

• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power

Transfer• Superposition

6

Norton Equivalent Circuit

• Independent current source in parallel with resistor• Provides simplified equivalence to more complex circuit• Relates to Thevenin Equivalent (source transformation)

7

Finding Norton Equivalent

8

Overview

• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power

Transfer• Superposition

9

With Dependent Source

10

Alternate Method

11

Overview

• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power

Transfer• Superposition

12

Power Transfer

• Two issues:– Efficiency of Power Transfer– Amount of Power Transfer

13

Maximum Power Transfer

14

Example

• Find value of RL that results in maximum power transfer.

• Use Thevenin Equivalent circuit.

15

Overview

• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power

Transfer• Superposition

16

Superposition

• Applies to linear system• Defined: when linear system is excited by >1

independent energy sources, the total response is the sum of individual responses.

• Clarified– Deactivate 1st source, find response from 2nd

source– Deactivate 2nd source, find response from 1st

source– Add these responses

17

In practice

• May not help so much right now…

18

w/Dependent Sources

19

Overview

• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power

Transfer• Superposition