3 Phase System - Input Power and Input Current calculation

Thread Starter

mishra87

Joined Jan 17, 2016
1,037
Hi All,
Sorry for asking silly question.
I want to calculate the input power and input current for forward converter.
Specification :
Output Power : 80W
Efficiency : 80% Assuming.
Line Voltage : 230Vrms (assuming single phase line voltage 230Vrms)
 

Papabravo

Joined Feb 24, 2006
21,225
Hi All,
Sorry for asking silly question.
I want to calculate the input power and input current for forward converter.
Specification :
Output Power : 80W
Efficiency : 80% Assuming.
Line Voltage : 230Vrms (assuming single phase line voltage 230Vrms)
The first order approximation would be output power divided by efficiency.

\( P_{IN}\;=\;P_{OUT}/\text{Eff}\;=\;80\text{ watts}/0.8\;=\;100\text{ watts} \)

Does that make sense?
 

Thread Starter

mishra87

Joined Jan 17, 2016
1,037
The first order approximation would be output power divided by efficiency.

\( P_{IN}\;=\;P_{OUT}/\text{Eff}\;=\;80\text{ watts}/0.8\;=\;100\text{ watts} \)

Does that make sense?
Hey...Thanks for reply !
yes, this makes sense.

Now lets say L1 = 230Vrms
L1-L2 = 230*1.73 = 398V
L1-L3 = 398V
L2-L3 =398V
In this case how to calculate the input current ?
 

Papabravo

Joined Feb 24, 2006
21,225
Hey...Thanks for reply !
yes, this makes sense.

Now lets say L1 = 230Vrms
L1-L2 = 230*1.73 = 398V
L1-L3 = 398V
L2-L3 =398V
In this case how to calculate the input current ?
I'm not that familiar with 3 phase calculations but there should be an RMS current, that when multiplied by 230 Vrms gives a power of 100 watts. Could it be approximately 0.435 Amperes(rms)? Probably not, but you need to run that down.
 
Last edited:

Thread Starter

mishra87

Joined Jan 17, 2016
1,037
I'm not that familiar with 3 phase calculations but there should be an RMS current, that when multiplied by 230 Vrms gives a power of 100 watts. Could it be approximately 0.435 Amperes(rms)? Probably not, but you need to run that down.
Thanks for your participation !
Looking forward some expert to jump in to the thread who has experience in 3 phase system.
Thanks !
 

Ian0

Joined Aug 7, 2020
9,817
IF you have a standard 6-pulse rectifier, then you will get a bus voltage of 565V DC, with ripple at 300Hz.
If the input power is 100W then there will be 33W supplied by each phase, so each phase current is 33W/230V = 0.143A at best but the power factor may not be too good.
 

Thread Starter

mishra87

Joined Jan 17, 2016
1,037
IF you have a standard 6-pulse rectifier, then you will get a bus voltage of 565V DC, with ripple at 300Hz.
If the input power is 100W then there will be 33W supplied by each phase, so each phase current is 33W/230V = 0.143A at best but the power factor may not be too good.
Hey Ian0,
Thanks you so much for joining the discussion !
Yes I have 6 diode for rectification.
1703577675128.png
 
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