I finished the new layout of the dual Mosfet H-bridge! With the help of EvanF I corrected many issues and after double checked everything, I can tell that this is a final version!
dual_simple_hbridge_1_2b.pdf- (214.06 KiB) Downloaded 8190 times
- dual_simple_hbridge_1_2b_bottom_single.pdf
- (28.13 KiB) Downloaded 6068 times
I increased a little more the distance between the mosfets and added status leds too! Now we can see the motor controller in action before hooking on it motors.
The diodes D1 - D8 that are marked as "D" on the PCB layout could be 1N5819 but you should do more research on alternatives as I think the correct ones to use are depending on the motor type.
The 15v Zeners are there to add a little delay on the "turn-on" time of the mosfets to match the "turn-off" time.
And finally decided to split the power sources for each bridge so one can use two different power sources, if different size motors is used. But I also did that to prevent extra current passing from the power lines, as each motor will draw from its own connector. In case you using the same power source (one car battery) for both motors, you can use a switch to turn them on, and also split the power cables like in the photo:
And to connect the power cables its preffered to use PCB cable connectors like this one:
Here is the Part list:
- dual_simple_Mosfet_hbridge_1_2b_parts.pdf
- (573.14 KiB) Downloaded 7980 times
dual_simple_Mosfet_hbridge_1_2b_parts.txt- (1.03 KiB) Downloaded 3965 times
There is a small "error" in the part list! The IRFZ44 part is actually the IRL44N model
(There is difference between "IRFZ44" and "IRLZ44N" !!!! You need the "IRLZ44N" ones!!!!!!
The ones without "N" are not able to fully turn on by the 5v logical system of the h-bridge! )
And a small guide to assemble it:
- DSMhb_1_2b_solder_guide.pdf
- (3.88 MiB) Downloaded 5309 times
And one important thing:
- Adding_Safety_Limit_Switches.pdf
- (23.39 KiB) Downloaded 3954 times
I was thinking to try to design another version of this dual h-bridge that will use two Mosfets in parallel in place of one, to be able to handle larger amp rates without much temperature rise. The current that the device passes is based, to a degree, on the Rdson value of the MOSFET (and, of course, on the load resistance and bus voltage). In addition to being dependent on the "gate drive voltage," the Rdson value will increase as the MOSFET’s junction temperature increases. So, if a MOSFET gets hot, it will pass less current because of a increasing Rdson value. Therefore, if two (or more) MOSFETs are connected in parallel, and one begins to heat up, it will eventually begin drawing less current than the cooler MOSFET of the pair, and subsequently cool down. This is assuming that all of the MOSFETs paralleled are of the same type. 100A plus H-bridge circuits can be realized with parallel MOSFETs!
More cool info on Mosfets can be found here: http://www.mcmanis.com/chuck/robotics/p ... power.html
Regards, Thanos
Germany - Frankfurt/M
New Zealand
SitemapIndex
RSS Feed