H-bridge using only n-channel mosfets

stube40 · Aug 26, 2010

I have created an H-bridge PC with 4x floating gate drivers and 4x IGBTs (see attached schematic showing half of h-bridge).

It works very nicely but I would like to replace the IGBTs with n-channel MOSFETs. However, all the H-bridge designs I've seen use n-channels on the low side and p-channels on the high side.

Since my design uses independant galvanically isolated DC-DC converters which effectively provide each of the 4x gate drivers with their own floating supply, is it possible that I can just do a simple straight swap between of the IGBTs with N-channel mosfets?

Militoy · Aug 26, 2010

I don’t see any problem using N-channel FETs instead of your IGBTs – virtually all of our SMPS bridges and half-bridges use N-FETs both top and bottom. I did notice that you have made no provision for a separate turn-off path to dump gate capacitance – so I assume your gate resistors are fairly low in value, and you’re taking other measures to prevent cross-conduction. We also typically put around 10K from gate to source, to prevent the gate from floating, when not being actively held off.

H-bridge using only n-channel mosfets

stube40

Attached Files:

igbt_-_1-2_h-bridge_1635.jpg

Militoy

N Channel Mosfets

P-channel N-channel MOSFETS

H-Bridge

h bridge

H-bridge with 4 N-ch FETs

N channel Mosfet

n-channel mosfet

Driving high inductance Solenoid using H-Bridge