Problem in stm32f103c8t6 while running motor on load condition

[svraj]

Hi friends, I am driving bldc motor using stm32f103c8t6. And i measure the rpm of the motor using the hall sensor pins.

While running motor on no load condition....

Motor runs good .

Rpm is also measured and i monitored in keil debugging session, which work fine.

While running motor on load condition....

Motor runs OK

Rpm is good but sometimes problem comes, that is in keil debugging session rpm value displays "can not evaluate".

So i connected led's in order to indicate rpm. On no load condition the led's works fine. At load condition the led's works OK but most of the times all led's blinks on and off (the time when the keil shows can not evaluate)

I don't know what happens while motor is on load condition. I then verified the micro controller's power supply using scope, which rises up to 700mV. What happens while motor is on load conditions, is any ripple making the controller to stop reading data???

[svraj]

I was expecting solution as this community is more significant for st micro controllers. Guys kindly give some ideas to get rid of this problem.

#[Power Management and Motor Control]​ #[STM32 MCUs]​ #STM32F1​ #Bldc​ 

[Ozone]

This forum is mostly populated by unaffiliated users, not ST expert staff. Unlike a fee-based helpdesk.

Getting expert opinion here is sometimes accidental.

Being more of a SW guy, I would suspect back-EMF issues from the motor.

If the motor itself is not galvanically isolated, avoiding back EMF issues in the MCU part becomes troublesome.

The debug interface is high-speed, asymmetric digital signals, relatively easy to interfere with.

[svraj]

Thanks for your response. Even I also doubted that Back EMF may be the cause of this problem. It directly impacts the power supply of the controller It will be helpful if anyone give some hunch about how to stop back emf affecting microcontrollers.

[Ozone]

If it impacts the power supply of the controller, it impacts low-energy signals and communication even more.

I'm no hardware guy, but a common method is to separate motor and high-power driver electronics from low-power control units.

Like optocouplers, or similar technology. Adding suppressor elements to your motor might help, too.

I'm a bit out of my comfort zone here, though.

[svraj]

Even though you are a SW guy, your suggestions are good. Thanks a lot I'll try with what you said.