ECEN 215, Principles of Electrical EngineeringDr. Mina RahimianLecture# 5 Date: 9/9/13B) when a voltage source exists in the circuit, there are two possibilities: case1: If the voltage source is connected between a node and the reference node, the voltage of that node voltage is known and equals the voltage of the source.case 2: If the voltage source is connected between two non-reference nodes, combine the two nodes to form a super node. Apply KCL at the super node. The difference between the two voltages equals the voltage of the source (constraint equation).A supernode should enclose the voltage source and any other elements in parallel with it.Mesh Current Method (Mesh Analysis)A mesh is a loop which does not contain any other loops.For mesh analysis, we take the mesh currents as the circuit variables. Mesh current is a ficticious quantity and is not necessarily the branch current.A) For a circuit without any current sources, take these steps:1. Identify the meshes and assign a current to each mesh.2. Apply KVL around each mesh. Use Ohm's law to express all voltages in terms of the mesh currents.3. Solve the KVL equations to find the mesh currents.B) when a current source exists in the circuit, there are two possibilities: case1: If the current source exists only in one mesh, set the mesh current equal to the current of the source. case 2: If the current source is shared by two meshes, create a super mesh by mentally removing the source and the elements connected in series with it. Then express the voltages around the super mesh in terms of the original mesh currents. Add a constraint equation which relates the currents of the combined meshes to the current of the source.Which method is preferred? In this example, using mesh analysis, there are 5 unknown currents.Using nodal analysis, there are only 2 unknown voltages.Source TransformationSource transformation is a simplification technique. It allows a voltage source in series with a resistor to be replaced by a current source in parallel with the same resistor, or vice
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