0
\$\begingroup\$

I'm fairly new and still learning so please forgive me if this isn't the most technically correct wording or diagram.

I built a circuit to work with Arduino using PWM and a simple MOSFET. My motor is 7.4 amp stall current and about 1-2 amps running. It's running off a 12.4v Lipo pack.

However, I now need to support braking. I don't need to support reverse and so many of the drivers out there are h-bridges, and I gather I only need a half h-bridge.

On paper, a half h-bridge appears to be just two MOSFET transistors. I can control speed with PWM on one, or set it to low and short the motor with the 2nd MOSFET for braking.

However, my circuit doesn't work, and I'm not sure why. I read some things and I'm thinking maybe it's related to voltage difference on the gate. In my old circuit, the MOSFET was used on the negative line for the motor, but that won't work with a half h-bridge.

enter image description here

\$\endgroup\$
  • \$\begingroup\$ Your thinking seems quite reasonable to me. Hint: Please have a look at the types of your mosfets. You have used 2 P-channel types, which only turn on with a negative gate-source voltage. \$\endgroup\$ – Stefan Wyss May 3 '18 at 4:52
  • \$\begingroup\$ Did you ever get this circuit figured out? I too am looking for a circuit using the same fqp30n06l MOSFETs. I also need braking as you explained and have no need for reverse so half bridge sounds like the reasonable solution. I do have a FQP27P06 P transistor I could use too but it is not logic level like the FQP30n06L. \$\endgroup\$ – mScientist Sep 26 '18 at 20:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.