ELECTRICAL AC AND DC 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