This document discusses electrical drives using AC and DC motors. It defines electrical drives as using around 50% of electrical energy for electric motors in industries and applications. The key components of electrical drives are the motor, power source, and control methods. For AC motor drives, the document discusses induction motors and synchronous motors. It also summarizes methods for controlling speed and torque of induction motors including stator voltage control, rotor voltage control, and frequency control. The document concludes that variable speed drives can improve energy efficiency compared to constant speed drives.

1. ELECTRICAL AC & DC DRIVES
BY
B . JAYASREE,
B . TECH EEE, 2nd YEAR

2. CONTENT
1. INTRODUCTION
2. ELECTRICAL DRIVES- DEFINITION
3. COMPONENTS IN ELECTRICAL DRIVES
4. INTRODUCTIONS: AC MOTOR DRIVES
5. STATOR VOLTAGE CONTROL
6. ROTOR VOLTAGE CONTROL
7. FREQUENCE CONTROL
8. ENERGY / COST SAVINGS
9. DC DRIVES Vs DRIVES
10. CONCLUSION
11. THANK YOU

3. INTRODUCTION
countries 65%
of the electric
energy is
consumed by
electric motors
1
DC motors play
a significant
role in modern
industrial
drives
2
DC motor can
provide a high
starting torque
3

4. ELECTRICAL DRIVES- DEFINITION
About 50% of electrical energy
produced is used in electric drives
today . Electric drives may run at
constant speed or at constant speed or
at variable speed.

5. COMPONENTS IN ELETRICAL DRIVES
1
MOTOR
2
DC
motors-
permane
nt magnet
–wound
field
3
AC
motors-
Induction,
synchron
ous,
brushless
4
POWER
SOURCE
5
DC –
batteries ,
fuel cell,
photovolt
aic
6
AC- single
-three-
phase
utility ,
wind
generator

6. THREE PHASE DRIVES
Three phase drives may
also be subdivided
into:

7. *A three phase half wave converter drive
operates in first quadrant and is limited to
applications up to 40KV
*A three phase full wave converter drive is
a two quadrant drive without any field
reversal , and is limited to applications up
to 1500KW

8. INTRODUCTIONS: AC MOTOR DRIVES
There are
two types
of ac
drives:
-Induction
motor drives
-Synchronous
motor drives
AC drives are
replacing dc
drives and
are used in
many
industrial
and
domestic
application

9. The speed and torque of induction motors can be
controlled by
Stator voltage control1
Rotor voltage control2
Frequency control3

10. STATOR VOLTAGE CONTROL:
The stator voltage can be varied by three
phase
*ac voltage controllers,
*pulse width modulation(PWM) inverters
They are used mainly in low power
applications, such as fans , blowers, and
centrifugal pumps , where the starting torque
is low.

11. FREQUENCY CONTROL
The torque and speed of induction motors
can be controlled by changing the supply
frequency.
At low frequency , the reactances decrease
and the motor current may be too high.
This type of frequency control is not normally
used.

12. ENERGY/COST SAVINGS
*System efficiency can be increase from
15% to 27% by introducing variable-speed
drives operation in place of constant speed
operation.
*For a lager pump variable-speed drive ,
payback periods – 3.5 years whereas
operating life is -20 years

13. DC DRIVES Vs AC DRIVES
Advantage
AC motors are less
expensive as
compared to dc
motors.
AC motors require
low maintenances
as compared to dc
motors.
Power
converters for
ac drives are
complex.
Power
converters for
ac drives
generates
harmonics in
the supply
system & load
circuit.
Disadvantage

14. CONCLUSION:
In India , We are using three phase ,
50Hz ac supply as an input . There
are so many that requires higher
frequency and phases for better
operation of industrial equipments .
Even though we are with same
frequency for particular applications
keeping economy in point of view.

15. THANK YOU