Induction Machines

1
Induction Machines

• EE 341 Energy Conversion
• Ali Keyhani
• Induction Machines
• lecture 1

2
Induction Machine
a
a
a
b
c
c
b
c
b
Fig. 1
3
Induction Machine
4

• Stator Winding

winding is located on the stator. (stator winding)
winding is located on the rotor. (rotor winding)

• Torque is produced from interactions of the two
  rotating flux waves.

5
The Rotating Stator Flux Wave
The flux variation of coil a-a when it is
energized can be written as
time changing flux produced by
6
(No Transcript)
7
D
P
x
0
D
2
P
For coils b - b and c - c
s
s
s
s
8
Total flux wave in the air gap of the machine.
9
The frequency of induced current in the rotor
winding.
A) Rotor at stand still
Is rotating in the air gap at the electrical
speed of
The equivalent mechanical speed of the rotating
10
This equation for mechanical speed is called the
synchronous speed
is mechanical speed of rotating
rotates
at
w.r.t stator
This
will induce voltage in short circuited rotor
winding.
Note (When the rotor is stationary)
11
Suppose the rotor is rotating at
The speed of
(Flux wave) produced by rotor w.r.t rotor
structure is
12
The electrical speed of rotor rotating flux wave
is
13
The Torque Production
of the stator rotates at
with respect to ?????
of the rotor rotates at
with respect to the rotor
structure.
of the rotor structure rotates at
(mechanical
speed) with respect to the stator.
14
Motor Action
and
are rotating in the same direction.
stator
Air gap
rotor
15
w.r.t stator structure
w.r.t rotor structure
motor action.
are rotating in the same direction.
and
16
Calculation of Slip
17
Note
rad/sec
rad/sec
but in rpm, we have
is the synchronous speed in rpm
is the rotor speed in rpm
(r.p.m.)