Mumbai University > Electronics Engineering > Sem7 > Power Electronics 2

Marks: 5M

1. The average output voltages for single phase full converter,

2. $V_{01} = ( 2V_mcos(α)) / π$ and 3-phase full converter,

3. $V_{03} = (3V_{ml} cosα) / π$

4. The derivation of the above average output voltages has been obtained on the assumption that current transfers from the outgoing SCRs to the incoming SCRs instantaneously.

1. This means that when incoming SCRs T1 and T2 are fired in a single phase full converter, Fig 1 , outgoing SCRs T3 and T4 get turned off due to the application of reverse voltage and the current shifts to SCRs T1 and T2 instantaneously. This is possible only if the voltage source has no internal impedance.

2. The source impedance is taken as purely inductive. It causes the outgoing and incoming SCRs to conduct together. During the commutation period, the output voltage is equal to the average value of the conducting phase voltages.

3. The effect of source inductance is

   • To lower the mean output voltage
   • To distort the output voltage and current waveforms
   • To modify the performance parameters of the converter