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EE 2315. Lecture 04 - Wye/Delta & Delta/Wye Conversions and Node Voltage Analysis. Wye/Delta Conversion (1/2). Wye. Delta. Wye/Delta Conversion (2/2). Delta/Wye Conversion. Effects of D -Y & Y- D Conversions. D -Y Conversion eliminates a loop but adds a node.
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EE 2315 Lecture 04 - Wye/Delta & Delta/Wye Conversions and Node Voltage Analysis
Wye/Delta Conversion (1/2) Wye Delta
Effects of D-Y & Y-D Conversions • D-Y Conversion eliminates a loop but adds a node. • Y-D Conversion eliminates a node but adds a loop.
Y-D Conversion Example Find Rab Several Methods: We choose to eliminate node c, then simplify.
Introduction to Node Voltage Method • More direct than branch equations • Fewer equations to solve • Choose one node as reference • Express all variables in terms of node voltages • Solution is set of node voltages w.r.t. chosen reference node • Solution completely defines the circuit
Node Voltage Example 1 (1/4) Apply KCL at Node 1: Use Ohm’s Law:
Node Voltage Example 1 (2/4) Apply KCL at Node 2: Use Ohm’s Law:
Node Voltage Example 1 (3/4) KCL for Node 1: KCL for Node 2:
Node Voltage Example 2 (1/2) KCL for Node 1: KCL for Node 2:
Node Voltage Example 2 (2/2) Substitute: into KCL equations Node 1: Node 2:
Node Voltage Example 2a (1/2) Substituting for ix:
Node Voltage Example 3 (1/2) KCL for Node 1: KCL for Node 2:
Node Voltage Example 3 (2/2) Substitute: into KCL equations Node 1: Node 2:
Node Voltage Example 3a (1/2) After Substitution:
Node Voltage Example 3a (2/2) Substitute and solve:
Node Voltage Example 4 (1/3) No KCL equation possible at node 1 or at node 2. KCL can be applied at the supernode.
Node Voltage Example 4 (2/3) KCL @ Supernode: Other relationships: and
Node Voltage Example 4a (2/2) Substitute and solve:
Alternative to Supernode (1/2) KCL @ Node 1: KCL @ Node 2:
Alternative to Supernode (2/2) Use Ix to get same info as Supernode: