Project

Development of Energy Saver for Induction Motors

Induction motors at light load run at low power factor and low efficiency. But  if  the  stator  supply  voltage  is  reduced  at  light  load  condition,  both the  efficiency  and  power  factor  can  be  improved  owing  to  reduction  in magnetizing  current  and  core  loss.  The  proposed  energy  saver  is  a thyristorized  phase  control  working  in  feed  back  mode.  The  motor  has a  unique  characteristic  of  slip-efficiency  as  well  as  slip-power  factor, which  do  not  vary  with  supply  voltage.  Therefore,  a  method  of  stator voltage  control  based  on  operating  power  factor  angle  has  been developed  which  will  make  the  motor  run  at  a  slip  that  corresponds  to maximum  efficiency  irrespective  of  the  load  condition.  The  change  in load  will  be  sensed  as  change  in  power  factor  and  the  supply  voltage will  be  varied  by  controlling  the  thyristor  firing  angle. A  three  phase chopper  control  of  the  induction  motor  using  a  different  algorithm  of minimizing  the  input  current  is  also  in  progress.