L6235 commutation scheme

[gspoerl9]

Posted on January 31, 2017 at 10:34

We got a problem with a specific motor:

With the standard connection one direction of rotation has a significant lower torque and also at 2 specific hall sensor states the current to the coil is switched off !

Changing the connection of the motor coils and Hall sensors ( OUT1-> coil2, OUT2->coil3, OUT3-> coil1 and the hall connections the same) cures the problem.

What is the reason for that ?

There is no hint in the data sheet, no hint in an application note. Also when i tried to get in contact with ST i failed. 

ST seems to have the philosophy 'our products, your problem' To get in contact with a FAE is impossible whether trying via distributors or even with a desperate call to ST headquarter here in Germany.

I regret very much to use a Product from ST because if there is an (even serious) problem one ist left alone!

Worst support ever !

#l6235

[Enrico Poli]

Posted on February 01, 2017 at 14:32

I'm sorry for your bad experience with our customer support.

For sure this is not the message we want to give to our customer.

Going back to your issue. 

Could you share the datasheet of the motor and some waveform about the anomalous behavior you obtain with the other configuration? (OUT1-coil1, OUT2-coil2, OUT3-coil3 and the same for the hall sensors, I guess).

[gspoerl9]

Posted on February 01, 2017 at 16:31

Hello Enrico,

very nice to get in contact with a real person at ST.

We are using an EC13 Motor from Maxon (430155). We also tried out different other motors from Maxon, they are all working.

Connecting the EC13 motor in the normal scheme (OUT1-coil1, OUT2-coil2, OUT3-coil3 ) one direction of rotation is working as expected, the other direction the current to the coil is switched off always at the Hall state H1 =L H2=L H3=H. This will stop the motor at slow speed.

Changing the connection of the motor to OUT1-coil2, OUT2-coil3, OUT3-coil1 and the hall sensors accordingly will cure the problem.

Changing the connection to OUT1-coil3, OUT2-coil1, OUT3-coil2 the problem returns but the motor will stop with at the hall state H1=L, H2=H, H3=L.

Looking at the hall signals with an oscilloscope during motion shows a pattern as expected just added with some noise.

We got the problem with the eval board L6235N and also with our own board with the L6235PD.

I bought also an eval board of the L6229 and this IC works without problems!!!!

Can you explain the behavior of the L6235 ? Why is the current to the coil switched off without showing anything on the DIAG Pin ?

Best regards

Georg Spörl

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Von: Enrico Poli

Gesendet: Mittwoch, 1. Februar 2017 14:33

An: Spoerl Georg

Betreff: Re: - Re: L6235 commutation scheme

STMicroelectronics Community <https://community.st.com/?et=watches.email.thread>

Re: L6235 commutation scheme

reply from Enrico Poli<https://community.st.com/people/Poli.Enrico?et=watches.email.thread> in Power Management and Motor Control - View the full discussion<https://community.st.com/message/145175-re-l6235-commutation-scheme?commentID=145175&et=watches.email.thread#comment-145175>

________________ Attachments : image002.jpg : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006Hyg8&d=%2Fa%2F0X0000000bEQ%2FW8O4Mc04fyXxUr.zVaywQMmFscPwPPUcJfWQTAzWQ5A&asPdf=false_EC13.pdf : https://st--c.eu10.content.force.com/sfc/dist/version/download/?oid=00Db0000000YtG6&ids=0680X000006Hyxh&d=%2Fa%2F0X0000000bES%2FQ3Pi4MnJzP0QP_IYMsvNSHr1TZRDbszFnE6JRzARRfU&asPdf=false