Ke problem configuration wizard

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berdeso
Level 1
Level 1
10 sign-ins 5 sign-ins First reply posted

Hello 

We used an EVAL-M1-101TF + EVAL-M1-05F804R configuration and we get a motor 1 VoltScl value out of range on the configuration wizard.

The DC bus sensing voltage low resistance is 13.3 Kohm and  DC bus sensing voltage high resistance is 510Kohm. at 10000RPM the BEFM should be arround 0.9v divided by 13.3/(13.3+510) give us 22mv wich is a low value. is it the problem ? 

In attachment you wil find the error , our measurement BEFM and mc2 file

 

Great regards,

Bernard

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1 Solution
psb
Moderator
Moderator
Moderator
250 sign-ins 25 solutions authored 100 replies posted

Based on the MCE Wizard motor parameters entered, the internal calculated value VoltScl is out of range. The eval boards with their given BOM are not compatible with the motor selected. The Ke value of the motor needs to be higher. Request you to share the motor datasheet to verify in case any changes can be made in the configuration. 

For changes in the hardware, increasing the low side dc sense resistor or decreasing the high side dc sense resistor will solve the problem of VoltScl out of range. 

Thanks,
Sai

Best Regards,
Sai

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7 Replies
psb
Moderator
Moderator
Moderator
250 sign-ins 25 solutions authored 100 replies posted

Hello @berdeso , 

    Can you please let me know how you've measured the back emf constant Ke. 
    From the file "befm.png" , is the waveform the line to line back emf waveform ? (having the pk value of around 0.47V rms line to  line and synchronous freq 93.63 Hz) 

    Error in the back emf constant, rated parameters, etc will cause error in the calculation of internal parameters like Rs, Lo, VoltScl, etc.  

 BEFM should be arround 0.9v divided by 13.3/(13.3+510) give us 22mv wich is a low value. is it the problem ?  - The Back EMF constant value must be entered as the V ln-rms/krpm, which is measured at the motor input terminals. 13.3k and 510k ohms are the scaling values for the DC bus voltage measurement.

Thanks,
Sai

Best Regards,
Sai
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berdeso
Level 1
Level 1
10 sign-ins 5 sign-ins First reply posted

Hello Sai,

I calculed Ke from question 7 : Epk/sqrt(6)/RPM*1000 * =  0.5/2.45/(120/14*93)*1000 = 0.25

Regards,

Bernard

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psb
Moderator
Moderator
Moderator
250 sign-ins 25 solutions authored 100 replies posted

The DC bus sense voltage divider needs to be adjusted accordingly to accommodate different DC bus voltage ranges. 

Best Regards,
Sai
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berdeso
Level 1
Level 1
10 sign-ins 5 sign-ins First reply posted

If I understand well , my motor is not compatible with EVAL-M1-101TF + EVAL-M1-05F804R configuration ?

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psb
Moderator
Moderator
Moderator
250 sign-ins 25 solutions authored 100 replies posted

Based on the MCE Wizard motor parameters entered, the internal calculated value VoltScl is out of range. The eval boards with their given BOM are not compatible with the motor selected. The Ke value of the motor needs to be higher. Request you to share the motor datasheet to verify in case any changes can be made in the configuration. 

For changes in the hardware, increasing the low side dc sense resistor or decreasing the high side dc sense resistor will solve the problem of VoltScl out of range. 

Thanks,
Sai

Best Regards,
Sai
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berdeso
Level 1
Level 1
10 sign-ins 5 sign-ins First reply posted

Hello,

I intend  to make my own power card.

So as  an example I have studied  your power card (EVAL-M1-05F804R) and I'm surprised   because there is no BEFM returned (VREF , UREF , WREF) , there is only one single shunt returned to the controler card ( EVAL-M1-101TF). How does it works ?

 

Regards ,

Bernard

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psb
Moderator
Moderator
Moderator
250 sign-ins 25 solutions authored 100 replies posted

Hello @berdeso , 

    For feedback, it is only the currents and the speed which are used in the control loop, not the voltages. Back emf is estimated or back-calculated from the estimated or sensed speeds and the other motor parameters. 

   Kindly refer to the initial portions of the iMotion Software Reference Manual to know about the block diagram of closed loop control and the required feedbacks. 

  Also, request you to create a new thread and  feel free to post your further queries and requirements on selecting the control card and also the power board. I'll be most happy to assist you with that. 

Thanks and Regards,
Sai

Best Regards,
Sai
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