H-BRIDGE schematics

[reviser]

I'm developing an h-bridge to control the speed and direction of rotation of a DC motor.
The motor I need to control is 24V 10A.
I've created a schematic for the the h-brigde but I'd like to hear some opinions about the overall schematic and/or the specific components I've selected.
Any suggestion is welcome.

[Bertho]

Don't use 1N4007 diodes. They are not designed for use in these type of circuits. You need a few high-speed/fast-recovery diodes. Otherwise you'll start to push the output voltage back into the lower voltage supply (and that really sucks if you are switching a few hundred volts at the output). I'm also not sure you need that much capacitance on the Vb trampoline.

[Kremmen]

The bootstrap diode should indeed be a fast low leakage type, which 1N4007 is not. The main reason to have a low leak diode is to preserve the charge of the bootstrap cap for the high side switch, in case there is a prolonged continuous on-time. For the gate discharge diodes you may want to consider something more appropriate as well. 1N4148 would be a jelly bean that should work OK.

Note that for motor control you don't need to switch both sides of the bridge, one side can be on constantly while the other is modulated. Independent control of all the switches allows you to additionally control the circulating current in the motor, for braking purposes.

Also, you may want to consider measuring and controlling the motor armature current. A 10 amp motor would take considerable current under stalling conditions. The traditional way is to measure the bridge voltage from the low side common leg and control modulation as needed.

Recommended reading: IR app note 987 at http://www.irf.com/technical-info/appnotes/an-978.pdf