Converter parameters

[thinker]

For the full wave three phase bridge thyristor converter there is a well known relationship between the RMS value of AC line current and a DC current: I(L)=0.815xI(d). Please advise what is the relationship between the above parameters for the IGBT-based PWM three phase bridge converter?

 

[electricuwe]

Basicly you can derive this from the fact that the converter itself can not store power. If you do not take efficiencny into account:

Sqrt3*U*I(L)* cosphi = Ud * Id

with U beeing the lini-to-line input voltage

With proper control and modulation you can choose any Ud above Sqrt2*U and the displacement power factor cosphi as you like

 

[thinker]

Thanks, electricuwe. If we assume the unity power factor (which is typical for PWM converter) and DC voltage equal to AC voltage amplitude, we get exactly the same relationship: I(L)=sgrt2/sqrt3 x Id = 0.815 x Id.