Variable frequency drives
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Variable frequency drives

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Variable frequency drives Variable frequency drives Presentation Transcript

  • VARIABLE FREQUENCY DRIVES
  • 1. Whatis VFD?2. Purpose Of VFD3. VFD System4. Drive Operation5. Operating Modes6. AC Induction motor7. components8. Advantages9. Function & Features10. Applications.
  • Variable Frequency DrivesThis technology has several different names suchas :• Variable speed drives.• Adjustable speed drives.• Adjustable frequency drives.• Frequency converter.
  • • pump and fan applications.• control and regulation.• Speeding up or slowing down a machine or process.• Protection from overload currents• Safe Acceleration
  • A variable frequency drives used in a drivesystem consisting of the following three mainsub-systems:• AC Motor.• Controller.• Operator Interface.
  • • In variable-speed applications, a dc motor may be operating in one or more modes: – Motoring. – regenerative braking. – dynamic braking. – Plugging. – four quadrants.
  • MOTORING
  • Three-phase motoroperation
  • • Torque is produced as the induction motor generates flux in its rotating field.• This flux must remain constant to produce full-load torque.
  • The speed of the rotating electric field withinthe induction motor.Synchronous Speed = 120 x frequency no. of motor poles
  • • All VFD’s need a power section that converts AC power into DC power.• This is called the converter bridge.• Sometimes the front end of the VFD, the converter is commonly a three-phase, full wave- diode bridge.• The DC bus is the true link between the converter and inverter sections of the drive
  • • Vacuum tubes.• Thyristors (SCR’s).• Transistors.
  • ms. Pulse-width-modulated voltage and current waveform
  • • Control of process temperature and pressure.• Maintenance costs can be lower.• Save energy.• Limit the torque
  • • Set-up Parameters• The Control Method• Acceleration or Accel-Ramp Rate• Automatic Restart• Stopping Method• Automatic Signals
  • • Water Supply Pump Application• Conveyor Application• Exhaust Fan Application• Compressor Application
  • • Significant energy savings• Easy setup & programming• Better design• Competitive edge