tapped inductor buck converter questions.

[johansen]

So it seems the tapped inductor buck converter is rarely employed.

I'm wondering if anyone knows of a different topology that could be employed to make a bi-directional buck converter to operate on a 10:1 voltage ratio without excessive losses and cost, without resorting to a synchronously rectified bi-directional transformer based topology.


The tapped inductor buck converter seems to me that the voltage across the high side switch, at turn off, will have the turns ratio of the inductor multiplied by the output voltage of the converter, added to the high side voltage stress on the switch.

This added voltage stress seems to me, to make the topology mostly useless, because with RDS_on increasing with the square of the voltage rating of the mosfet.

So suppose i make a 400v to 48v buck converter with a 2:1 inductor, at turn off the inductor has 48+1 diode drop volts on the secondary, 100+ volts on the primary. that 100 volts means the source of the high side mosfet is at least 100 volts below ground, so the gate driver has to be totally isolated.

an energy absorbing snubber then has to collect that -100 volts and dump it back into either the load or the high side.. not easy.

thoughts?

[Andy Chee]

The thread topic seems misleading.

The root question is whether it's possible to have bi-directional transfer without synchronous switches.  AFAIK, the answer is no.