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5 replies posted 5 sign-ins First reply posted
I’ve got a serious problem with a IMC101 implementation.

We’ve been using a IMC101 in one of our products for a while now, and it’s been working ok for the most part.
However, our customer has been unhappy with its stall behavior and jerky start-up, so we’ve decided to switch from flux sensing to using hall sensors.

Everything had been going well with just switching the sensor configuration and angle calculation methods in the wizard.
We were really happy with its performance until we tested it in the opposite direction.

When running with speed in the positives (we’d been testing with negative speeds), after loading the motor down and releasing, the speed would suddenly and rapidly increase, well beyond the limit of what should be possible.
The config is set for a maximum speed of 300RPM, but I would guess the motor would reach over 1000RPM before having to manually shut it down.
Once the behavior happened, starting the motor from idle would result in the same crazy acceleration to excessive speeds, seemingly ignoring the target speed, direction, and ramp speed.
Only cycling the power to the unit would fix the problem, at least until the next time the motor was loaded down again while running in the positive direction.

I don’t understand how this is possible. Are there not protections in place to prevent this kind of speed runaway? I’m now worried that this sort of thing could happen to our units in the field.

The wizard and designer software we’re running are version, and the firmware was originally V1.03.01 but I’ve since upgraded to V1.03.03 with no improvement.

I’ve attached the config and wizard files, as well as the only graph I was able to get before our development unit fried. It shows the motor rapidly accelerating to what appears to be 1100RPM when starting from idle to a set target of -55RPM, before being stopped.
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