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| DIC - Current fed double inductor push-pull and other current fed topologies |
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| Miyuki:
Buck stage will be needed not only as soft start but also to regulate overload and shut down as input inductors have relative high stored energy I must do some layout and at least simulate it from layout expected values, but now it looks like nice simple converter for my purposes with relative low loses at semiconductors |
| T3sl4co1l:
Note that the transistors explode if they both turn off at the same time. A current fed inverter is in its off state when that current is held at 0V (both switches on)! This is obviously in conflict with the voltage source shown, so be careful. TVSs to absorb the inductor energy in shutdown (fault), or a current source (usually a buck stage), are needed. (To use a single buck, use one inductor to supply current to the CT of the transformer. A TVS or snubber may still be needed to deal with transformer leakage, but this is considerably less than the main series inductance, no big deal.) Tim |
| jbb:
Well, my precharge idea didn’t work out nicely. (It involved a secondary pair of switching FETs with series resistors but dissipated way too much power.) I still think it’s a shame to add a whole buck stage - for high current too! - to precharge the output. Are you planning to use a precharge resistor for the input capacitor? Maybe one 24V inrush limiter can be used to precharge both input and output cap? (Also there should be a fuse somewhere in the battery circuit.) Thinking about shutdown, we see that we need to absorb all the inductor energy, but not very often. So an overvoltage snubber circuit (2 diodes, capacitor, substantial TVS) may be sufficient. |
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