Hi,

If I need a solid 350VDC output from a 3-phase generator, can someone point me to the equations to use to figure out how much peak to peak voltage I must maintain on the output of the generator to achieve the DC voltage out using a 3-phase rectifier?

Thanks!

 

Hello,

When you rectify an 3 phase signal, the top voltage is the same as in a single phase.
The avarage voltage will be higher as in a single phase, beacouse the ripple is much smaller.
See also teh AAC eBook :
http://www.allaboutcircuits.com/vol_3/chpt_3/4.html

Greetings,
Bertus

 

Thanks what is the equation to determine the average DC voltage output of the 3 phase rectifier?

Hello,

When you rectify an 3 phase signal, the top voltage is the same as in a single phase.
The avarage voltage will be higher as in a single phase, beacouse the ripple is much smaller.
See also teh AAC eBook :
http://www.allaboutcircuits.com/vol_3/chpt_3/4.html

Greetings,
Bertus

 

Hello,

Here ia a page on the OPERATION OF A 3-PHASE FULLY-CONTROLLED RECTIFIER
http://services.eng.uts.edu.au/~venkat/pe_html/ch05s1/ch05s1p1.htm
There ia also a mathcad simulation available.

Greetings,
Bertus

 

Hi,

If I need a solid 350VDC output from a 3-phase generator, can someone point me to the equations to use to figure out how much peak to peak voltage I must maintain on the output of the generator to achieve the DC voltage out using a 3-phase rectifier?

Thanks!

Vdc=1.35*VL

Vdc=output voltage of the rectifier
VL=RMS value of the line voltage

 

Vdc=1.35*VL
Vdc=output voltage of the rectifier
VL=RMS value of the line voltage

That's an extremely rough approximation even at low voltages, and the accuracy is much worse at higher voltages.

A closer approximation would be:
Vdc=1.4142*(VL-VF)
where:
Vdc= output of the rectifier
VL = RMS of the line voltage
VF = Forward voltage of the rectifier(s) in series
But this still does not account for smoothing capacitors and current in the circuit.