This document discusses different types of electric motors. It describes the basic components of a DC motor including the rotor, stator, and air gap. It then discusses advantages of series and permanent magnet DC motors. Permanent magnet DC motors have higher efficiency and power density. Synchronous motors require supplemental mechanisms to start but provide precise speed control. Induction motors are the most common type due to their simple and rugged design, and can operate at constant speed from no load to full load. However, variable speed control requires a variable frequency drive.

2. Motor construction
• Rotor
• Stator
• Air gap
• Windings

3. Parts of DC Motor

7. Series Motor
Advantages of DC series
motors:
• Huge starting torque
• Simple Construction
• Designing is easy
• Maintenance is easy
• Cost effective

8. Permanent Magnet DC Motor
• Higher efficiency since no electrical energy is used or losses
incurred for developing or maintaining the motor’s magnetic
field.
• Higher torque and power density.
• Linear torque speed charcteristics. that are more predictable.
• Better dynamic performance due to higher magnetic flux
density in air gap.
• Simplified construction and essentially maintenance-free.
• More compact size.
http://www.ohioelectricmotors.com/permanent-magnet-dc-motors-649#ixzz2sttph8bA

9. Advantages
simple torque and speed control without
sophisticated electronics

10. General Torque Equation
Translational (linear) motion:
dt
d
JT


Rotational motion:
dt
dv
MF 
F : Force (Nm)
M : Mass (Kg )
v : velocity (m/s)
T : Torque (Nm)
J : Moment of Inertia (Kgm2 )
 : angular velocity ( rad/s )

12. Synchronous Machines

15. • Above a certain size, synchronous motors are
not self-starting motors. This property is due
to the inertia of the rotor; it cannot instantly
follow the rotation of the magnetic field of the
stator.

16. • synchronous motor produces no inherent
average torque at standstill, it cannot
accelerate to synchronous speed without
some supplemental mechanism.

17. Applications
• Synchronous motors are especially useful in applications
requiring precise speed and/or position control.
• Speed is independent of the load over the operating range
of the motor.
• Speed and position may be accurately controlled using
open loop controls, e.g. stepper motors.
• Low-power applications include positioning machines,
where high precision is required, and robot actuators.
• They will hold their position when a DC current is applied to
both the stator and the rotor windings.
• Increased efficiency in low-speed applications (e.g. ball
mills).

18. Induction Motor
• Asynchronous motor
• AC electric motor

19. Introduction
• Three-phase induction motors are the most
common and frequently encountered
machines in industry

20. Induction Motor
• The electric current in the rotor needed to
produce torque is induced by electromagnetic
induction from the magnetic field of the stator
winding.
• Does not require mechanical commutation

21. – simple design, rugged, low-price, easy maintenance
– wide range of power ratings: fractional horsepower to
10 MW
– run essentially as constant speed from no-load to full
load
– Its speed depends on the frequency of the power
source
• not easy to have variable speed control
• requires a variable-frequency power-electronic drive for
optimal speed control