Transcript Basic Electrical Circuits & Machines (EE-107)

Basic Electrical Circuits &
Machines (EE-107)
Course Teacher
Shaheena Noor
Assistant Professor
Computer Engineering Department
Sir Syed University of Engineering & Technology.
Basic Nodal and Mesh analysis
In this chapter, we introduce two
different ways to view electric
circuits.
Basic Nodal and Mesh Analysis
• Nodal Analysis:
– It is based on KCL.
• Mesh Analysis:
– It is based on KVL.
• Both methods allow to construct equations for
a wide variety of circuits.
Nodal Analysis
Method:
• Use when (normally) multiple sources are
present.
• Convert voltage sources into current sources.
• Identify all the nodes and choose a reference
node.
• All the nodes (except reference node) are then
numbered and their corresponding voltages
are designated. V1, V2, . . .
Nodal Analysis
Steps:
1. We will assume V1 > V2 > V3... > 0.
2. Draw an arrow beside each passive component (resistor)
showing the direction that current flows through it
(made on the assumption made in step 1. For example)
V1
V2
10 Ohm
3. The arrow is drawn from V1
towards V2, because current
always flow from the higher voltage node to the lower
voltage node.
4. Label each arrow with the current it represents,
expressed in term of node voltages.
V1
V2
5. Write KCL at each node10and
Ohm solve the equations
Nodal Analysis
Drill Problem 4.1 (Page 71)
• For the circuit given below, compute the
voltage across each current source.
V1
2A
15 Ohm V2
7 Ohm
5 Ohm
3 Ohm
4A
Nodal Analysis
(Drill Problem 4.2) Page 74
• For the circuit given below, compute the
voltage across each current source.
2 Ohm
1 Ohm
3A
4 Ohm
3 Ohm
5 Ohm
Reference Node
7A
Mesh Analysis
• Mesh analysis requires that all the sources in a
circuit be voltage source.
• The next step is to draw closed loops in the
circuit, each loop representing a path around
which KVL will be written.
• The direction of each loop is arbitrary.
• It may be either clockwise or counter
clockwise.
Mesh Analysis
• It is convenient to think of each loop as
representing a current that flows around the
loop and we designate each by an appropriate
symbol I1, I2 and so on.
• These loop currents are the unknowns in the
set of simultaneous equations that results
when KVL is written around each loop.
• Thus the number of unknown (loop currents)
is the same as the number of equations.
Mesh Analysis
Drill Problem 4.5 (page 80)
• Determine i1 and i2 in the circuit shown
below.
14 Ohm
10 Ohm
5 Ohm
6V
i1
i2
5 Ohm
5V
Mesh Analysis
Drill Problem 4.6 (page 80)
• Determine i1 and i2 in the circuit given below:
5 Ohm
4 Ohm
10V
i2
9 Ohm
i1
3V
10 Ohm
1 Ohm
7 Ohm