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Ghassen
Level 2
10 replies posted 5 questions asked 25 sign-ins
Level 2

Hi !

I have a little problem , actually I am turning a BLDC motor with the TLE987X EVALB_VQFN with Code exemple "BLDC FOC SENSORLESS " at the begining everything went well and I could drive the motor and change the speed ,  but when I put a load on the motor  ( to measure efficiency of the board)  , within a cetain threshold   of load the current doesn't increase anymore and the speed of the motor decrease at the same time and can't turn the load anymore , so I wanted to know if there is any limitation of current in the code or configuration parameters ? or what is the problem that causing this?

Also in the config wizard in motor paarameters (attached screenshot) is the " Phase resistance"   should I  put the resistance between 2 phases or one phase ? (also for inductance ).

Thank you for your help .

Best regard

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5 Replies
Raj_JC
Moderator
Moderator 250 sign-ins 25 likes received 50 solutions authored
Moderator

Hi @Ghassen,

For the current ratings, you can update them in the config wizard. Goto FOC motor parameters section for these settings. Please, refer to section 5.3 of the ‘Sensorless Field Oriented Control with Embedded Power SoC’ document. Check if these current ratings are getting breached, if they are update them in the config wizard.

>> For the Phase Resistance and Inductance values, please insert their per phase values. Which will be half of the measured phase-to-phase resistance in star connection.

 

Please, let us know if you need further clarification.

Thank you

Best Regards

Raj Chaudhari

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Ghassen
Level 2
10 replies posted 5 questions asked 25 sign-ins
Level 2

Hi @Raj_JC 

Thank you for   your assistance , I already checked the ConfigWizard when I had current limitation problem and I found that I have the same config that are in  ‘Sensorless Field Oriented Control with Embedded Power SoC’ , I mean the max nominal current was 5A  and the problem that when I try to drive the motor with a certain load the current can't  exceed 1.4 and start to decrease  an the speed decreat at the same time  which is still too low campring with 5A so that's why I didn't understant what is going on ?

I can send you the video to understand what is happening exactly if there is a way .

Thank you .

Best regards.

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RupakC
Moderator
Moderator 100 sign-ins 25 solutions authored 50 replies posted
Moderator

Hello @Ghassen 

You can add your waveforms in your reply here as well.
I have a few questions in mind. While the motor is running, did you check the motor input voltage at the motor terminals ? Also, please check your DC link voltage. A fall in DC link voltage will cause a fall in motor input voltage and then the motor current will not increase as expected. Similarly, a reduced motor input voltage will also limit the motor input current.

You may share these waveforms (may be video) with us such that we can analyze your problem and find a solution for you. Also, it would be good if you could share your ConfigWizard settings with us. 

Regards

RupakC
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Ghassen
Level 2
10 replies posted 5 questions asked 25 sign-ins
Level 2

Hi @RupakC 

Thank you for your assitance , I don't have a waveform I am just seing the current value on the power generator screen  that is decreasing when I  reach a certain load threshold , i measured  the input voltage on the motor and it never changes even when the motor doesn't turn anymore when I reach this load threshold and the current is decreasing , so I really didn't what is causing this  current drop ?

This is a  google drive link for a  video of the situation that can show you the problem : https://drive.google.com/file/d/1azXxrgdUlh-GKrJzkxvUBOmiyd2BWJZ9/view?usp=sharing.

you will find also attached my configwizard settings and my motor datasheet.

 

Thank you.

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RupakC
Moderator
Moderator 100 sign-ins 25 solutions authored 50 replies posted
Moderator

Hello @Ghassen 
I tried to run our motor at our lab with the VQFN board and the sensorless FOC code and the motor runs properly without any issues.
I have a few things which I feel are necessary to check.
1. I feel that your input voltage to the motor is saturating. To confirm, can you let me know the exact magnitude (rms or maximum) of the motor input voltage such that we can back calculate the modulation index to know if the voltage is saturated. A waveform of the motor input voltage for the entire operation would be nice, but knowing the magnitude will also help us.
2. What are the values of Kp and Ki gain in the speed controller parameters.
3. What are the closed loop FOC current settings?
4. Could you apply a lighter load or apply the load slowly and check?
5. What is the current rating of your power supply? If you have a maximum current limit set in the power supply, make sure it is set to allow more than 1.5A input current.
Please let us know your observations on the above points.

Regards

RupakC
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