This presentation is about the basic concepts of Electrical Drives System, what it is and how it is working etc

2. Electrical Drives
(AC & DC)
[with Applications of Power Electronics]
Presented By: Fareed Ahmed Shaikh (16EL-42)
Quaid-e-Awam University of Engineering, Science and Technology
Nawabshah, Sindh, Pakistan

3. Contents
• Why we need drives?
• Introduction
• ELECTRIC DRIVES
• Components in Electric Drives
• Classification
Energy/Cost Savings
DC DRIVES V/S AC DRIVES
Conclusion

4. Introduction
In some countries nearly 65% of the total
electric energy produced is consumed by
electric motors.

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

6. Why do we need drives?
• The first question that pinch our mind is why we
need Drives?
• Are the Motors not sufficient and Reliable?
• If they are then why drives?

7. Why do we need drives?
• The answer to the question is: We need the control
over machines and that is not gained by a simple
construction

8. Background
• Nowadays, modern power electronics and drives are used in
electrical as well as mechanical industry.
• The power converter or power modulator circuits are used
with electrical motor drives, providing either DC or AC
outputs, and working from either a DC (battery) supply or
from the conventional AC supply.

9. Electrical Drive?
• An electrical drive can be defined as an electromechanical
device for converting electrical energy into mechanical energy
to impart motion to different machines and mechanisms for
various kinds of process control.

10. Cont’
• An electrical drive is an industrial system which performs the
conversion of electrical energy into mechanical energy or vice
versa for running and controlling various processes.
• An electrical drive is defined as a form of machine equipment
designed to convert electrical energy into mechanical energy
and provide electrical control of the processes.
• The system employed for motion control is called an electrical
drive.

11. Drives are systems employed for motion control
Require prime movers
Drives that employ electric motors as
prime movers are known as Electrical Drives

13. Cont’
• FEASIBLE CONTROL CHARACTERISTICS
• AVAILABLE IN WIDE RANGE OF SPEED TORQUE AND POWER
• HIGHER EFFICIENCY
• LOWER NOISE
• CLEANER OPERATION
• LOW MAINTENANCE REQUIREMENTS
• ELECTRIC ENERGY IS EASY TO TRANSPORT

14. TYPES OF ELECTRICAL
DRIVES
• GROUP DRIVE
• INDIVIDUAL DRIVE
• MULTIMOTOR DRIVE

15. GROUP DRIVE
• DRIVE CONSISTS OF ONLY ONE ELECTRIC MOTOR
WHICH DRIVES SEVERAL MACHINES
• ADVANTAGE
• RATING OF AN ELECTRICAL DRIVE CAN BE
SMALLER
• DISADVANTAGE
• IF ELECTRIC MOTOR IS SUBJECTED TO ANY FAULT
ALL THE EQUIPMENTS BECOME IDLE

16. INDIVIDUAL DRIVE
• IF A SINGLE MOTOR IS USED TO DRIVE A SINGLE
MACHINE AND ALL THE MECHANISMS BELONGING
TO THE SAME MACHINE.
• DISADVANTAGE
• DUE TO POWER LOSS ,THE EFFICIENCY OF SUCH
DRIVE IS ALSO POOR

17. MULTIMOTOR DRIVE
• A SEPARATE MOTOR IS PROVIDED FOR DRIVING THE
SEPARATE MECHANISM
• ADVANTAGES
INCREASE THE OVERALL PRODUCTIVITY

18. FACTORS AFFECTING THE
SELECTION OF DRIVE
• LIMIT OF SPEED RANGE
• EFFICIENCY
• BRAKING
• STARTING REQUIREMENTS
• POWER FACTOR
• LOAD FACTOR
• AVAILABILITY OF SUPPLY
• ECONOMICAL ASPECTS

19. SELECTION OF MOTOR BASED ON
LOAD VARIATION
• CONTINOUS LOAD
• CONTINOUS VARIABLE LOAD
• PULSATING LOAD
• IMPACT LOADS
• SHORT TIME INTERMITTENT LOAD
• SHORT TIME LOAD

20. CLASSES OF DUTY AND SELECTION OF
RATING OF MOTOR
• ONCE CYCLE OF VARIATION OF LOAD IS DUTY
• CONTINOUS DUTY
• CONTINOUS DUTY,VARIABLE LOAD
• SHORT TIME DUTY
• INTERMITTENT PERIODIC DUTY
• INTERMITTENT PERIODIC DUTY WITH STARTING
• INTERMITTENT PERIODIC DUTY WITH STARTING AND
BRAKING

21. 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

22. DC DRIVES V/S AC
DRIVES

23. COMPARISON BETWEEN AC AND
DC DRIVE

24. Advantages:
• Ac motors are less expensive as compared to dc motors.
• Ac motors require low maintenance as compared to dc motors.
• Cost is too low as compared to another system of the drive.
• The system is more simple and clean.
• The control is very easy and smooth.
• Flexible in the layout.
• Facility for remote control.
• Transmission of power from one place to other can be done
with the help of cables instead of long shafts, etc.
• Its maintenance cost is quite low.
• It can be started at any time without delay.

25. Disadvantages
• Power converters for ac drives are complex.
• Power converters for ac drives generates harmonics in the
supply system & load circuit.

26. APPLICATIONS OF ELECTRICAL DRIVES
• Electric drives are used in boats,
• Traction systems,
• lifts, cranes, electric car, etc.
• They have flexible control characteristics. The steady state
and dynamic
• characteristics of electric drives can be shaped to satisfy the
load requirements.
• They are available in wide range of torque, speed, and
power.
• They can be started instantly and can immediately be fully
loaded.
• They can operate in all the four quadrants of the speed-
torque plane.
• They are adaptable to almost any operating conditions such
as explosive and radioactive environments.

27. Conclusion
In Pakistan, 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 equipment.
Even though we are with same frequency for particular
applications keeping economy in point of view