content Introduction: ELECTRIC DRIVES - A DEFINITION Block diagram of Electrical drive: Components in electric drives DC drives classification in various types Single-Phase Half-Wave-Converter Drives: Three-phase drives Ac motor drives Introduction: AC Motor Drives Stator Voltage Control: Rotor Voltage Control: Frequency Control: DC DRIVES Vs AC DRIVES Conclusion: Thank u......

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4. Introduction:
 In some countries nearly 65% of the total
electric energy produced is consumead by
electric motors.
 DC motors play a significant role in
modern industrial drives.
 DC motors can provide a high starting
torque.

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

6. Block diagram of Electrical drive:
• Small
• Efficient
• Flexible

7. Components in electric
drives
Motors
• DC motors - permanent magnet – wound field
• AC motors – induction, synchronous , brushless DC
 Power sources
• DC – batteries, fuel cell, photovoltaic - unregulated
• AC – Single- three- phase utility, wind generator -
unregulated

8. • DC drives can be classified, in general, into three
types:
 1. Single-phase drives
 2. Three-phase drives
 single-phase drives may be subdivided into:
 Single-phase half-wave-converter drives.
 Single-phase full-converter drives.
 Single-phase dual-converter drives.

9. Single-Phase Half-Wave-Converter Drives:
The applications of this drive are limited to the 0.5 kW
power level.

10. Single-Phase Full-Wave-Converter Drives
 It is a two-quadrant drive, and is limited to
applications up to 15 kW.

11. • Three-phase drives may also be subdivided
into:
-Three-phase half-wave-converter drives.
– Three-phase full-converter drives.

12.  A three phase half wave converter drive operates in
first quardant and is limited to applications upto
40kw.
 A three-phase full-wave-converter drive is a two-
quadrant drive without any field reversal, and is
limited to applications up to 1500 kW.

13. Introduction: 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
applications

14. • The speed and torque of induction motors can be
controlled by
– Stator voltage control
– Rotor voltage control
– Frequency control

15. 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.

16. Rotor Voltage Control:
• The typical torque-speed characteristics for variations
in rotor resistance

17. 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.

18. Energy/Cost Savings
 System efficiency can be increased from 15% to 27% by
introducing variable-speed drive operation in place of constant-
speed operation.
 For a large pump variable-speed drive, payback period ~ 3-5
years whereas operating life is ~ 20 years

19. DC DRIVES Vs AC DRIVES
Advantages:
 Ac motors are less expensive as compared to dc
motors.
 Ac motors require low maintenance as
compared to dc motors.
Disadvantages:
 Power converters for ac drives are complex.
 Power converters for ac drives generates
harmonics in the supply system & load circuit

20. Conclusion:
 In India, we are using three phase,50hz ac supply as an input.
There so many applications that require higher frequency and
phases for better operations of industrial equipments. Even
though we are with same frequency for particular applications
keeping economy in point of view.