MCSPTR2A5775E: MPC5775E Development Kit

[Gayan_Niroshana]

Hello,

I hope someone will be able to help me here.

I'm using MCSPTR2A5775E: MPC5775E Development Kit with PMSM motor to test motor control algorithms specially with Field Weakening. 

https://www.nxp.com/design/development-boards/automotive-motor-control-solutions/mpc5xxx-solutions-/...

Initially I'm Observing the implementation of FOC motor controlling with field weakening using the original example code provided for the kit by NXP with the help of MCAT Tool and Free-master debugging tool.

Provided example code -  https://www.nxp.com/downloads/en/board-support-packages/MCSPTR2A5775E_SW.exe  

MCAT Tool - https://www.nxp.com/design/software/development-software/motor-control-application-tuning-mcat-tool:...

In the provided GUI, Field Weakening can be turned ON or OFF by selecting ON/OFF command. But in Speed FOC Control Mode there isn't any noticeable difference in D axis current and voltage waveforms for both cases (Field Weakening ON/OFF); output D-axis voltage of D-axis current PI controller takes a negative value for both cases. 

Only noticeable difference is the maximum speed setting limit. (2475rpm with field weakening OFF & Around 4000rpm with field weakening ON).

Is there another method to monitor when Field Weakening is exactly on or off, like observing some variables rather than the provided Filed Weakening ON/OFF command in the GUI.

Thanks and Regards,

Gayan.

[Lukas2]

To test Field Weakening (FW), you must select option “ON”. Basically, you could do it anytime you want.  FW algorithm itself has automatically activated above speed 4300 rpm. It is the point where the maximum DC bus voltage is reached. At this stage, to weaken the magnetic field of permanent magnets, the d-axis current becomes negative, and your speed can be further increased.

[Lukas2]

Captured variables describes the FW function operation. Please check if you see the same behaviour.

[Gayan_Niroshana]

Hello @Lukas2 ,

Thank you very much for your response. Yes I could observe similar behaviour from Id waveform later on. At the beginning I was kind of miss led by the speed limit around 2000rpm set by the program for the operation without field weakening. And I couldn't find the base speed of the motor mentioned anywhere (Which is 4500rpm).

Then I was able to reach around 4600rpm with FW on. Beyond this speed the Id waveform get unstable and motor stops. Is this the maximum rpm we can obtain using the default program ?

Best Regards,

Gayan.

[michalvidlak]

Dear Gayan,

the maximum achievable speed of the attached PMSM with the default settings and applied FW is around 4600 rpm, as you mentioned. The base speed is lying around 4300 rpm. What you have seen as a d-axis current instability is just a phase current limitation. The speed can be further increased by enlarging the phase current limit. However, it is not recommended due to possible permanent magnets demagnetization and inverter damage.

Kind regards,

Michal.

[Gayan_Niroshana]

Thank you very much @michalvidlak .

With best regards,

Gayan.

[petervlna]

Hello,

I was talking to kit owner. It is not so simple with motor mounted on kit.

He will prepare some measurements and answer here.

Best regards,

Peter

[Gayan_Niroshana]

Hello,

Do you have any updates on this topic?

Hope someone who works with the kit would be able to provide more information as mentioned.

Best Regards,

Gayan. 

[petervlna]

Hello,

Not so far.

I have notified him once again.

Best regards,

Peter

[Gayan_Niroshana]

Ok, looking forward for a reply.

Thanks & Regards,

Gayan.

[petervlna]

Hello,

I have notified him once again.

He told me he is working on it but has not finished it atm.

Maybe due to workload before year end.

Best regards,

Peter

[Gayan_Niroshana]

Hello @petervlna ,

Ok, thanks for the update.

Best regards,

Gayan.

[Gayan_Niroshana]

Thank you.

Best regards,

Gayan.

[Gayan_Niroshana]

In the provided GUI, Field Weakening can be turned ON or OFF by selecting ON/OFF command. But in Speed FOC Control Mode there isn't any noticeable difference in D axis current and voltage waveforms for both cases (Field Weakening ON/OFF); output D-axis voltage of D-axis current PI controller takes a negative value for both cases. 

Also, D axis current (which is an important parameter for field weakening) doesn't show any noticeable difference.