These are the ranges of the value Irms under most conditions of winding
and capacitor and wiring leakage inductance and series resistance as
developed by theory. For a design point I would suggest using Irms =
2Idc. Steve is correct.
Tomm
Steve Thompson wrote:
>KD7QAE wrote:
>
>
>>For the major types of filters the secondary RMS current is related to
>>the DC load current as:
>>
>>Inductor input: 0.7
>>FWCT capacitor input: 1.0 to 1.2
>>FWB capacitor input: 1.6 to 1.8
>>
>>Data from O.H. Schrade: "Analysis of Rectifier Operation"
>>
>>
>I agree these are the ranges of figures that 'drop out' most often - but
>I'd caution against automatically assuming that they cover every
>instance. In the last case, if you have 1.9 instead of an assumed 1.7,
>there's 25% more heat.
>
>In the absence of using PSU Designer or somesuch to predict values,
>0.7xIdc for choke input and 1.7xIdc for capacitor input are also useful
>estimates of the rms ripple current in the smoothing caps.
>
>Steve
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