26-02-2013, 11:22 AM
An Application of Power Electronics
An Application.ppt (Size: 5.12 MB / Downloads: 209)
What is Power Electronics ?
A field of Electrical Engineering that deals with the application of power semiconductor devices for the control and conversion of electric power
Power Electronic Systems
Typically used in systems requiring efficient control and conversion of electric energy:
Domestic and Commercial Applications
Industrial Applications
Telecommunications
Transportation
Generation, Transmission and Distribution of electrical energy
Overview of AC and DC drives
DC drives: Electrical drives that use DC motors as the prime mover
Regular maintenance, heavy, expensive, speed limit
Easy control, decouple control of torque and flux
AC drives: Electrical drives that use AC motors as the prime mover
Less maintenance, light, less expensive, high speed
Coupling between torque and flux – variable spatial angle between rotor and stator flux
After vector control drives were introduced (1980s)
AC motors used in high performance applications – elevators, tractions, servos
AC motors favorable than DC motors – however control is complex hence expensive
Cost of microprocessor/semiconductors decreasing –predicted 30 years ago AC motors would take over DC motors
Modeling and Control of Electrical Drives
Va is the average voltage over one period of the waveform
- sampled data system
Delays depending on when the control signal changes – normally taken as half of sampling period