21 March 2017

Type E Chopper ( Class E Chopper )

  • The type E chopper is a four quadrant chopper. The type E chopper is parallel combination of two typeC chopper
  • The combination of chopper CH1, chopper CH2, diode D1 and diode D2 makes one type C chopper and other is made from chopper CH3, chopper CH4, diode D3 and diode D4.

Working

First quadrant

  • When chopper CH1 and chopper CH2 are switched on, the load current flows through (+)Vdc – A – CH1 – LOAD – G – CH2 – K – Vdc( – ). 
  • The output voltage and current both are positive therefore it is called as first quadrant operation.

Fourth quadrant

  • When chopper CH1 and chopper CH2 are switched off, the stored energy of inductor dissipates through F – LOAD – G – H – D3 – D –(+)Vdc – Vdc( – ) – D4  – F. 
  • The output voltage is negative but output current is positive during this period therefore it is called as fourth quadrant chopper operation.

Third quadrant

  • When chopper CH3 and chopper CH4 are switched on, the load current flows through (+)Vdc – C – CH3 – G – LOAD – F – E – CH4 – Vdc( – ). 
  • The output voltage and current both are negative therefore it is called as third quadrant operation.

Second quadrant

  • When chopper CH3 and chopper CH4 are switched off, the stored energy of inductor dissipates through G – LOAD – F –D1 – (+)Vdc – Vdc( – ) – L – D2 – H – G. 
  • The output voltage is positive but output current negative during that period therefore it is called as second quadrant operation.
  •  The DC supply is short circuited if chopper CH1 and CH4 or chopper CH2 and CH3 is simultaneously switched on. 
  • When the chopper works in first and third quadrant, the output voltage is always less than the input voltage resulting it is step down chopper
  • Similarly when the chopper works in second and fourth quadrant, the output voltage is always greater than the input voltage resulting it is step up chopper