STSPIN32F0A BLDC Sudden motor stops

[Cristian Dobre]

Posted on March 10, 2018 at 13:49

Hello,

I am in the process of developing a custom sensored BLDC driver board using STSPIN32F0A IC. The motor used to develop this board is very small and uses less than 10W of power. For now, the lab power supply is set to 2A current limit and a voltage of 7.4V to simulate a 2 cell LiPo battery. 

When accelerating the motor very fast, the voltage drops and this trips the undervoltage protection of the chip thus stopping the motor and the LDO regulator. This isn't a board issue since it also occurs on the STEVAL-SPIN3202 board. 

This situation may occur in real applications where the LiPo battery is undersized or it has a low charge. Since the gate driver voltage is the culprit here, can it be supplied externally to the VREG12 pin from another source? 

Does the IC support different power supplies for the motor and gate driver sections when using a 2S battery? I can only find a reference to connecting it to VM but this doesn't help since the current surge occurs on VM. I can't find a clear answer in the absolute maximum ratings section of the datasheet. 

Have a great day!

[T J · Accepted solution]

Posted on March 11, 2018 at 13:44

http://www.st.com/content/ccc/resource/technical/document/datasheet/group3/3d/88/0f/d1/3f/0c/49/80/DM00406030/files/DM00406030.pdf/jcr:content/translations/en.DM00406030.pdf

 

page 9,  VM  45V maximum before it blows up...

since the drive fets are off chip,

the VM trace can be adjusted slightly between the STspin32F0 Pin VM and the MotorFets VM. <- spikes from here

here I have added spike suppression and 100uF capacity to the STspin VM pin.

[Cristian Dobre]

Posted on March 14, 2018 at 11:24

Thanks for your reply, I'll try it out using the devboard. 

[T J]

Posted on April 03, 2018 at 00:19

did it work ?

[Cristian Dobre]

Posted on April 03, 2018 at 05:33

Yes, it did.