X-Nucleo-IHM08M1 3Sh and Nucleo-F746ZG use MotorControl Workbench 5.4.5 Over current

[KChie.1]

I use MotorControl Workbench 5.4.5 to control BLDC, but it always send error "over current". I check all setting but not have mistake in MotorControl.

The warning displayed by MotorControl Workbench is due to over current with my settings, but the Max current provided by my power supply is only 6A. And I setting my overcurrent protection 10A.

How can I solve?

I use MotorControl Workbench 5.4.5 to control my BLDC.

Control board: NUCLEO-F746ZG

Motor drive: X-NUCLEO-IHM08M1

Compilation tools: IAR EW for Arm 8.40.1

Other setting details are in this article:https://community.st.com/s/question/0D53W00000xpiEDSAY/xnucleoihm08m1-with-nucleof746zg-can-connect-mcsdk-warning-overshoot-current

[Cristiana SCARAMEL]

Hi @KChie.1​,

as reported in the X-NUCLEO-IHM08M1 user manual UM1996 the Over Current Protection (OCP) is implemented by hardware with a detection circuit.

By default the comparator threshold (Vref) is 0.3 V.

Had you modify the resistor divider value to obtain 1 V of Vref?

E.g. replace the R180 with a 14 kohm (or a value as close as possible).

 

Let me know if this info helped you.

[KChie.1]

Hi Cristiana SCARAMEL (ST Employee),

Thanks your reply,

In addition to follow the steps of Motor Profiler, I don't modify the board.

I measured the resistance value of R180 to be 3Kohm and Vref is 0.3V.

And R179 is not 33Kohm, It is 4.65Kohm.

1. Do I have to change R180 to 14Kohm to meet the expected stable operation now? or R179 change to 33Kohm?
2. Now I know OCP is implemented by hardware, but must all X-NUCLEO-IHM08M1 product have to change this?
3. If my bldc change , should R180 also change?

​regards

[Cristiana SCARAMEL · Accepted solution]

Hi @KChie.1​,

the Vref value is set by resistor divider (R179 and R180) connected to 3.3 V.

Vref = 3.3V x (R180 / (R180+R179) )

If you measure 0.3 V and R180 = 3 kohm, it means that R179 is 33 kohm (the right value).

When you measure the R179 have you remove the resistor from PCB?

Otherwise you may have a misleading measurements due to of parallel paths of 3.3 V supply voltage.

If do not want to remove the R179 you can check the serigraphy on the top that must be "333".

1. If you want an OCP of 10 A, you must have Vref = 1V. You can choose which resistor to change to obtain 1V.
2. All X-NUCLEO-IHM08M1 have the OCP set by hardware
3. If you want to change the OCP value, you must change the Vref value and so the R179 and/or R180 value. If you have different BLDC motor but you want to use the same OCP value it is not necessary change anything.

I hope I have clarified your doubts.