Methods of Analysis
90 likes | 374 Views
Methods of Analysis. Circuits 1 Fall 2005 Harding University Jonathan White. Outline. Nodal Analysis Define a symbol for all unknown node voltages. Write KCL at each node where variables occur Using Ohm’s Law, solve resulting equations. Mesh Currents Set up the currents Use KVL
Methods of Analysis
E N D
Presentation Transcript
Methods of Analysis Circuits 1 Fall 2005 Harding University Jonathan White
Outline • Nodal Analysis • Define a symbol for all unknown node voltages. • Write KCL at each node where variables occur • Using Ohm’s Law, solve resulting equations. • Mesh Currents • Set up the currents • Use KVL • Methods to solve linear equations • Substitution • Determinants • Calculator • Method from Numerical Methods
Nodal Analysis • Steps: • Define a voltage at every node in the circuit • Note: Some may be known, such as the source and ground • Write KCL at the nodes where the unknown voltages exist • Now, plug into these KCL equations with the unknown voltages, remembering how Ohm’s Law works. In this case, I = (VH – VL)/R, because we are writing voltages for nodes, not just resistors. Since current flows from a higher potential to a lower potential, the voltage over a resistor that is connected to 2 nodes is just VH – VL • Other current and voltage sources must be factored in to either the KCL equations or the unknown voltages. They sometimes actually make the equations easier. • Solve for the unknown voltages.
Nodal Analysis Example 1 Find all voltages and currents.
Nodal Analysis Example 2 Find Vo + Vo -
Mesh Currents • Steps: • Label each unknown current in each mesh, going clockwise. • A mesh is a loop which does not contain any other loops within it. • Also, write down the polarities of the currents as they go through each resistor. • Write KVL equations for each mesh. In this case, use V=I*R. When resistors are in both meshes, I=(I1-I2). • Use Ohm’s Law to express the voltages in terms of the mesh currents. • Again, you may need extra equations if there are other current/voltage sources. • Solve for the unknown currents.
Mesh Current Example - 1 Calculate the mesh currents.
Mesh Current Example - 2 Find the current through the 1 ohm R
Methods of Solving Sets of Equations • Calculator • rref function • solve function • Linear Algebra • Substitution • Graphing • Euclid’s Method