Issue with TB6612 overheating with HP 1:30 motors

RiO · April 13, 2009, 9:32am

I use baby-O-168 with two 1:30 HP motors (https://www.pololu.com/catalog/product/1093) for a line-tracer robot.

Normally it would run OK, but occasionally the robot may start jerking with one motor, while the other runs OK, and TB6612 H-Bridge would get very hot.

I had to change the motors for Maxon 13017, which are no less powerful. They operated very reliably without any glitches. Would anyone know why Orangutan B-168 and Pololu HP 1:30 did not work together well?

in response; on 4/12 Ben:

I’m sorry to hear that the 30:1 HP micro metal gearmotors didn’t work out well for you. What voltage were you running the motors at? In general, the HP versions of our micro metal gearmotors are a little beyond what we recommend for the TB6612 motor drivers on the Baby Orangutan since their stall currents at 6V exceed what the Baby Orangutan can deliver continuously. In an application like a line follower, the many minor corrections you make to motor speed as you drive can cause the motor to rapidly alternate between high and low speeds, which can put the average current draw well above the free-run current and closer to the stall current. It sounds like this was overheating the Baby Orangutan’s motor drivers and causing the thermal protection to kick in. Out of curiosity, what is the stall current of your Maxon motors at 6V?

Maxons’ Stall current is 1.2 A at 6V. Full specs here: http://web.archive.org/web/20070626092529/www.banebots.com/pc/MP-MISC/MP-13017
Actually I used 1:50 HPs, but their 6V stall current is same 1.6 A. Oh, and besides I used 7.5 -8 Volt supply (6 NiMH)
I am not sure that this is simple overheating - my robot would run in tests for 10 minutes with small interruptions with no problems. The H-Bridge chip was not even warm. But then suddenly it would refuse to run. Also, the problem would go away itself with time, but it would take definitely more than several minutes.

I just wonder, if anyone else had such issue with HP motors and TB6612?
What is the recommended driver / controller for these motors with 7.5 - 9 V power supply?

jan · April 13, 2009, 4:43pm

Hello,

We do not have a good driver we like for the HP motors, at least at higher voltages. The best option I know of is using the two H-bridges on the TB6612 in parallel. Have you tried putting a heat sink on your motor driver? If it’s close to working as it is, maybe that little bit of help will be enough.

- Jan