MOSFET H-Bridge DC Motor

[erik_l]

Hi Everyone,

I am new to the forum, so I apologize in advance if I've made any mistakes in posting this question here

I am working on an electronics project for Uni and am trying to design a basic circuit that can power a DC motor in two directions. I am planning to use an H-bridge design using MOSFETs as electronic switches. I've attached a rough diagram of my proposed circuit and will be using the following components below:

MTP3055E MOSFETs
1N4004 Diodes
YG2732 DC Motor (rated 12V, 4-18Vmax)

Obviously the gate voltage of 5V would only ever be applied to Q1 and Q4 OR Q2 and Q3 to provide the opposite rotations in the motor.

Do you guys think this design will work or am I missing some crucial bits here?

Any feedback would be greatly appreciated!

**broken link removed**

 

[MikeMl]

Q1 and Q3 are acting as source followers, so to turn then on fully, you have to apply ~20V to their gates.

Usually, the top-side devices are PFETs, because they can be turned off by applying 12V to their gates, and ~0V to turn them on...

Unless Q2 and Q4 have unusually low thresholds (i.e. "logic level" gates), they require more like 8 to 10V to turn them on hard.

 

[erik_l]

Hi Mike, thanks a lot for your reply. I've just seen in the spec sheet for the MOSFET in question that the Gate Threshold Voltage is 2-4V, so I think your suggestion of using a higher value such as 10V makes good sense. Do you think I'd be able to activate Q1 and Q3 by using a 20V DC source, then use the same 20V source + appropriate resistor to activate Q2 and Q4?

 

[MikeMl]

No time tonight, but there have been lots of H-Bridge circuits and threads on these forums over the years.

 

[ronv]

Unless you just want to build the descrete design it might be better to use something like https://www.electro-tech-online.com/custompdfs/2010/10/sn754410.pdf. It should be about the same price as your descrete design but will give you "blow up" protection and flexability (like input voltage).