Lecture 6: Thevenin and Norton Equivalents, Maximum Power Transfer, & Superposition Nilsson & Riedel ENG17 (Sec. 2): Circuits I Spring April 17, 2014

Overview Thevenin Equivalent Norton Equivalent Special Cases Maximum Power Transfer Superposition 2

Thevenin Equivalent Circuit 3 Independent voltage source in series with resistor Provides simplified equivalence to more complex circuit

Finding Thevenin Equivalent 4

Overview Thevenin Equivalent Norton Equivalent Special Cases Maximum Power Transfer Superposition 5

Norton Equivalent Circuit 6 Independent current source in parallel with resistor Provides simplified equivalence to more complex circuit Relates to Thevenin Equivalent (source transformation)

Finding Norton Equivalent 7

Overview Thevenin Equivalent Norton Equivalent Special Cases Maximum Power Transfer Superposition 8

With Dependent Source 9

Alternate Method 10

Overview Thevenin Equivalent Norton Equivalent Special Cases Maximum Power Transfer Superposition 11

Power Transfer Two issues: –Efficiency of Power Transfer –Amount of Power Transfer 12

Maximum Power Transfer 13

Example 14 Find value of R L that results in maximum power transfer. Use Thevenin Equivalent circuit.

Overview Thevenin Equivalent Norton Equivalent Special Cases Maximum Power Transfer Superposition 15

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 1 st source, find response from 2 nd source –Deactivate 2 nd source, find response from 1 st source –Add these responses 16

In practice May not help so much right now… 17

w/Dependent Sources 18

Overview Thevenin Equivalent Norton Equivalent Special Cases Maximum Power Transfer Superposition 19