Slide 1Equivalent SourcesA More Realistic Source ModelI-V RelationshipOpen Circuit VoltageShort Circuit Currentvoc(t) and isc(t)Slide 8Equivalent Current SourceVoltage and Current SourcesSource TransformationExample: Averaging CircuitSource TransformationsSlide 14A Single Node-Pair Circuit!Class Examples• Ideal sources vs. realistic sources• Open circuit voltage, Voc• Short circuit current, Isc• I - V relationship• Source transformationLecture 7. Realistic Sources & Source Transformation12Equivalent Sources•An ideal current source has the voltage necessary to provide its rated current.•An ideal voltage source supplies the current necessary to provide its rated voltage.•A real voltage source cannot supply arbitrarily large amounts of current.•A real current source cannot have an arbitrarily large terminal voltage.3A More Realistic Source Modelvs(t)Rs+-The CircuitA Realistic Source:Modeled by an ideal source in series with a resistori(t)+-v(t)4I-V RelationshipThe I-V relationship for this source model isv(t) = vs(t) - Rs i(t)v(t)i(t)5Open Circuit Voltage•If the current flowing from a source is zero, then it is connected to an open circuit.•The voltage at the source terminals with i(t) equal to zero is called the open circuit voltage:voc(t)6Short Circuit Current•If the voltage across the source terminals is zero, then the source is connected to a short circuit.•The current that flows when v(t) is zero is called the short circuit current:isc(t)7voc(t) and isc(t)v(t)i(t)voc(t)isc(t)8voc(t) and isc(t)•Since the open circuit voltage and the short circuit current determine where the I-V line crosses both axes, they completely define the line.•Any circuit that has the same I-V characteristics is an equivalent circuit.9Equivalent Current Sourceis(t) RsThe Circuiti(t)+-v(t)sssRtvti)()( 10Voltage and Current SourcesVs+-RsIs RssssIRV sssRVI 11Source Transformation•Equivalent sources can be used to simplify the analysis of some circuits.•A voltage source in series with a resistor is transformed into a current source in parallel with a resistor.•A current source in parallel with a resistor is transformed into a voltage source in series with a resistor.12Example: Averaging CircuitHow can source transformation make analysis of this circuit easier?+-Vout1k1k1kV1+-V2+-13Source Transformations+-Vout1k1k1kV1+-V2+-14Source Transformations+-Vout1k1kV1 /1k1kV2 /1k15A Single Node-Pair Circuit! k31k11k11k111eqRk1k121VVIeq 21031VVIRVeqeq16Class Examples•Drill Problems P3-3 and
View Full Document
Unlocking...