AMCLIB_ACIMRotFluxObsrv input parameters

[General_motor_control]

We have a three-phase induction machine (IM), of which we want to know the following motor parameters:

Rs:            stator resistance [Ohm]

Ls:             stator inductance [Henry]

Lm:           magnetizing inductance [Henry]

Rr:             rotor resistance [Ohm]

Lr:              rotor inductance [Henry]

For sensorless control of the IM, we use the AMCLIB_ACIMRotFluxObsrv and AMCLIB_ACIMSpeedMRAS. Rs and Ls are measured and verified - thus certain. However, executing the no-load and blocked-rotor test results in Lm >> Lr, Ls (magnetizing inductance greater than the product of stator- and rotor-inductance), which seems legit comparing to other papers and/or results found online. However, fltKrLsTotLeakGain from the AMCLIB_ACIMRotFluxObsrv ends up to be a negative gain in this way as the formula is:

((Lr * Ls) - Lm^2) / Lm

This seems to be faulty? Because a negative gain will not work out. What could be a possible cause?

[Celeste_Liu]

Hello @General_motor_control ,

Thanks for your post.

I believe that there is something wrong with your understanding. In the T-equivalent circuit, there is the following formula. For example, in the (PDF) On the Identifiability of Steady-State Induction Machine Models Using External Measurements

The Lm is the mutual equivalent inductance, it should be less than Ls, Lr. So the fltKrLsTotLeakGai formula in document CM7FAMCLIBUG.pdf is correct. Please check your parameter definition or test method.

Hope it can help you.

BRs,

Celeste

[General_motor_control]

Hello @Celeste_Liu 

Please find the answer of another NXP employee on my question through the following link: https://community.nxp.com/t5/Model-Based-Design-Toolbox-MBDT/AMCLIB-ACIMRotFluxObsrv-input-parameter... 

What are your thoughts on this? We were redirected to this forum.

Kind Regards,

[Celeste_Liu · Accepted solution]

Hello @General_motor_control ,

He knows more about motor control software libraries. You should trust him. I only analyzed based on the T-equivalent circuit, so my view might not cover everything. Sorry for that.

BRs,

Celeste

[Veronika_techsupport]

Hello @General_motor_control 

could you please clarify what particular NXP product you reffered to? 

Model Based Design Tools (MBDT) are supported by our MBDT experts via NXP technical community only.

Could you please submit a new community thread here: https://community.nxp.com/community/mbdt 

Our experts will gladly help you there.

[General_motor_control]

Dear Veronika,

We use an MKV58 on a custom PCB. So no specif MBDT. However, we do use the standard NXP libraries from the AMCLIB - as mentioned previously - the AMCLIB_ACIMRotFluxObsrv and AMCLIB_ACIMSpeedMRAS. 

Document: https://www.nxp.com/docs/en/user-guide/CM7FAMCLIBUG.pdf

Kind Regards,