DC link and rectifier model, Active current as function of voltage?

  • #1
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Hi, I'm trying to form an expression for a rectifier supplying a DC link with current, without actually rectifying a 3-phase input. Usage of the model is really only concerned with the RMS values and the active power drawn from the AC supply.

The DC link is just a capacitor so that:
dVDC/dt = (iDC - iL)/C

Based on what I've experienced with actual DC links, I chose the drawn rectifier current, iDC, to be a design constant multiplied with a function of DC voltage squared:
iDC = k*(Vpeak - VDC)2

Now, I wonder if this model can be used, i.e is there a design constant that will fit an actual rectifier?

Obviously, there is a certain relationship between Active Power/Active Current and the voltage drop on the DC link, I am just not sure if the square model here fits reality? Any comments to this is highly appreciated.

Regards, Arne Ranvik
 

Answers and Replies

  • #2
43
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The model should approximate a basic 3-phase passive rectifier, half-wave I think, so that a fully loaded (rated power draw) rectifier so that the measured DC-voltage will show something like VDC = 1.35*VRMS, compared to the unloaded case where VDC = √2*VRMS
 

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