Node Voltage Method

1
Node Voltage Method

• Select a reference node
• Label to all the non reference nodes
• Identify any super nodes
• Write the constraint equations for each super
  node
• Write Kirchoffs current law equations at each
  node and super node

2
Selecting a reference node

• Look for a node that connects a large number of
  elements
• Look for a node with a large number of voltage
  sources or control voltages connected to it

3
Labeling nodes

• Assign a number or letter to each node
• The node voltage for each node is then designated
  with the assigned number or letter used as a
  subscript

4
Identifying Super nodes

• Two or more nodes connected together by voltages
  sources form a super node
• If one of the nodes of a super node is the
  reference node then the voltages at all the other
  nodes of that super node are given by the
  algebraic sum of the voltage sources connecting
  them to the reference node.

5
Writing constraint equations

• If one node of a super node is the reference node
  then the voltage at the other node is given by
  the value of the connecting voltage source
• For all other nodes in a super node the
  difference between the two node voltages is the
  value of the connecting voltage source

6
KCL for node equations

• The current leaving a node through a resistor is
  given as the voltage at that node minus the
  voltage at the other node divided by the
  resistance connecting the two nodes
• Sum all the currents leaving each non reference
  node
• Sum all currents leaving all the nodes of a non
  reference super node, ignoring the currents
  through the voltage sources between nodes of the
  super node