lecture 6: equivalent circuits, max power transfer, superposition nilsson & riedel 4.10-4.13...
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Lecture 6: Equivalent Circuits, Max Power Transfer, SuperpositionNilsson & Riedel 4.10-4.13
ENG17 (Sec. 1): Circuits I
Summer 1 2014
July 1, 2014
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Overview
• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power
Transfer• Superposition
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Thevenin Equivalent Circuit
• Independent voltage source in series with resistor
• Provides simplified equivalence to more complex circuit
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Finding Thevenin Equivalent
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Example
Find equivalent w.r.t. a-b. Then, find I.
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Overview
• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power
Transfer• Superposition
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Norton Equivalent Circuit
• Independent current source in parallel with resistor• Provides simplified equivalence to more complex circuit• Relates to Thevenin Equivalent (source transformation)
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Finding Norton Equivalent
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Overview
• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power
Transfer• Superposition
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With Dependent Source
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Alternate Method
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ExampleFind RN and IN
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Overview
• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power
Transfer• Superposition
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Power Transfer
• Two issues:– Efficiency of Power Transfer– Amount of Power Transfer
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Maximum Power Transfer
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Example
• Find value of RL that results in maximum power transfer.
• Use Thevenin Equivalent circuit.
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Example
Find the value of RL for maximum power transfer. Find the maximum power.
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Overview
• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power
Transfer• Superposition
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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
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In practice
• May not help so much right now…
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w/Dependent Sources
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Example
Use superposition to find vo.
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Overview
• Thevenin Equivalent• Norton Equivalent• Special Cases• Maximum Power
Transfer• Superposition