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sudip_k
Level 2
Level 2
25 sign-ins 10 replies posted 10 questions asked

Hi,

 

I am working on a bldc motor driver based on IMC102T controller and I would like to know more about reducing acoustic noise as mentioned in the reference manual. 

I have a bldc motor that has just 10 pole /12 stator slots and generates some audible noise when it's running at higher speed especially(above 700rpm). To be precise, I can't exactly identify the source of the noise. And I am just guessing if that is the PWM modulation noise coming from the motor windings.  I even tried increasing the switching freq to 22khz but still I can hear the noise. I have even turn off the overmodulation and only enabled 3 phase PWM. 

my application requires very low acoustic noise and I want to know if changing from single leg(current configuration of my board) to multi leg sensing will help in reducing noise? If so could you explain how?

additionally, if you could help me on achieving very low acoustic noise while running using the IMC102contoller  would mean a lot.

 

Thanks

 

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1 Solution
Krupashankar
Moderator
Moderator
Moderator
500 replies posted 50 likes received 25 likes received

Hi @sudip_k,

Can you please check if the Resistance, Inductance and Back-emf Constant is per phase value? As the motor parameters in MCE Wizard are per phase values.

For more details refer to How to Measure Motor Parameters 

Can you please try the following parameter setting in MCE Wizard:

  • Please enable any one of the starting method ( Open loop, Parking Or the Initial angle sensing)
  • Ques 58: Current Regulator Bandwidth 200-500 rad/sec adjust based on the application
  • Ques 60 : Flux Estimator Time Constant - 3 msec
  • Ques 88: Enable Low Noise Phase Shift Current Sensing - Enable
  • Ques 90: Phase Shift Window Size- Adjust to minimum value

Please let us know if this helps to reduce the noise.

After following the above methods please ensure if the noise is not caused by the mechanical vibration of the setup.

 

Thanks,

Krupashankar

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3 Replies
Krupashankar
Moderator
Moderator
Moderator
500 replies posted 50 likes received 25 likes received

Hi @sudip_k,

Reasons for acoustic noise in Single shunt current measurement :

  • PWM is phase shifted from the actual pattern.
  • Minimum pulse is introduced for Single shunt current measurement

These modifications in PWM pattern is different from the actual pattern results in acoustic noise.

Proper current sensing scheme and proper tuning of motor can reduce the acoustic noise

Can you please share motor datasheet, Power board schematics and MCE Wizard (.mc2 )file in a zip format this will help us to understand the issue better.

 

Thanks,

Krupashankar

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Hi @Krupashankar ,

Thank you for the reply, As for the power board, I went back and tired with EVAL-M3-CM615PN and EVAL-M3-102T (that I had earlier) to verify the noise ,both(EVAL-M3-CM615PN and my custom board) generate the same noise. I can share my custom board schematic to your email in private.  

 

Thank you

 

 

 

 

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Krupashankar
Moderator
Moderator
Moderator
500 replies posted 50 likes received 25 likes received

Hi @sudip_k,

Can you please check if the Resistance, Inductance and Back-emf Constant is per phase value? As the motor parameters in MCE Wizard are per phase values.

For more details refer to How to Measure Motor Parameters 

Can you please try the following parameter setting in MCE Wizard:

  • Please enable any one of the starting method ( Open loop, Parking Or the Initial angle sensing)
  • Ques 58: Current Regulator Bandwidth 200-500 rad/sec adjust based on the application
  • Ques 60 : Flux Estimator Time Constant - 3 msec
  • Ques 88: Enable Low Noise Phase Shift Current Sensing - Enable
  • Ques 90: Phase Shift Window Size- Adjust to minimum value

Please let us know if this helps to reduce the noise.

After following the above methods please ensure if the noise is not caused by the mechanical vibration of the setup.

 

Thanks,

Krupashankar

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