ELECTRICAL MOTORS_2003uyumlu.ppt

1. ELECTRICAL MOTORS

2. ELECTRICAL MOTOR TYPES
Electric Motors
AC DC
Asynchronous Synchronous
3 Phase Brushless DC
Sinewave
Hyteresis
Step
Reluctance
Permanent Magnet
Wound Field
Universal
Single Phase

3. DC MOTOR
 Consists of rotor
and stator
 DC voltage is
applied to rotor
through carbon
brushes

4. DC MOTOR
 Resultant
magnetic
field of the
stator is
static

5. DC MOTOR

6. DC MOTORS
 DC controlled by an H-
bridge consisting of
four power switches.
They enable you to
adjust the motor
voltage and polarity
using the Pulse Width
Modulation (PWM)
technique. Thus speed
and direction of the
motor can be
controlled.

7. AC (ALTERNATING CURRENT)
MOTORS
 Lack of permanent magnets,
 magnetic induction to develop flux in the rotor
 less expensive than the PM rotor
 larger size, weight and inertia as compared to the
same rating for a PM brushless motor.
 Common type of rotor used with asynchronous
motor is squirrel cage
 No electrical connection between the stator and
the rotor

8. ASYNCHRONOUS MOTOR
 The difference between the rotor speed
and the rotating magnetic field is known
as slip
 Slip is dependent on load
100



s
r
s
N
N
N
%slip

9. 3-PHASE AC MOTORS

10. 3-PHASE AC MOTORS

11. BLDC MOTORS
 Brushless Type
• the rotor incorporates the magnets
• the stator contains the windings
• Controlling brushless motors(electronic commutation) is more
complicated than controlling brush motors(mechanical
commutation)
• Brushless motors need to know the electrical position to
perform commutation.
 There are two main commutation methods used in industry today:
• sine-wave
• six-step

12. SIX STEP COMMUTATION
 the drive and
feedback devices
can be simpler
 higher torque
ripple
 the efficiency of
torque production
is lower
Step Current flow
1 From phase A to phase B
2 From phase A to phase C
3 From phase B to phase C
4 From phase B to phase A
5 From phase C to phase A
6 From phase C to phase B

13. BLDC MOTORS

14. SINEWAVE COMMUTATION
 current in all three windings
simultaneously
 produce the smoothest and most efficient
torque possible
 extend the speed range
 increase torque output
 Allow angle advance
 IA = IT * sin(Elec Position)
IB = IT * sin(Elec Position - 120 degrees)
IC = IT * sin(Elec Position - 240 degrees)

15. BLAC MOTORS

16. SINEWAVE vs 6-STEP
COMMUTATION

17. BLDC MOTORS
 Applications
• PC fans
• Ceiling fans
• Blowers
• Washing machines
• Electrical Power Steering
• Industrial drive
• Servo drives
• Electric vehicle traction drive
• Automotive applications
• Refrigerator
• AirConditioning
• Fan

18. STEPPER MOTORS
 Commutation of current through discrete stator windings resulting
in the synchronous rotation (stepping) of the rotor
 Speed is proportional with the frequency of commutation pulses
 No real-time feedback is provided
 Low cost solution for position control
 Inherent "zero-following" error in servo systems
 Easy to interface to digital controllers
 Inherently high torque/position gain resulting in excellent holding
torque
 Limited holding torque available even when the motor is
unpowered
 Heat is generated in the stator and is easy to remove


19. STEPPER MOTORS

20. STEPPER MOTORS

21. STEPPER MOTORS

22. SPEED TORQUE CURVES
Actual
MotorMotorlard323_L15_s4
_35Arms_21V_corrected.xls
.pdf Data Sheet

23. BRUSHED DC Motors
Series-Wound DC Shunt-Wound DC

24. BRUSHED DC MOTORS -2
Compound-Wound DC

25. SPEED-TORQUE CURVES

28. DC (DIRECT CURRENT)
MOTORS
• Brush Type
• Brushless Type