topic Re: How to calculate the Motor Parameters for 6 pole pairs bldc motor in Motor Control and Smart Energy

How to calculate the Motor Parameters for 6 pole pairs bldc motor

haarism19 — Wed, 19 Dec 2018 15:34:10 GMT

Dear NXP team,

I am using MC-LVBLDC motor driver and FRDM KV11z for driving a motor, but the motor is not spinning at all. After going through the code, I observed that the motor parameters in "m1_bldc_appconfig.h" are for 2-Pole pair motors and I am using a 6 pole pair motor. Is there any documentation where it provides how to calculate those motor parameters.

Can this be the reason why my motor is not spinning because of the motor parameters? The motor I'm using is EMAX RS1106. It would be of great help if you could look into this situation

Thank you,
Haaris

Re: How to calculate the Motor Parameters for 6 pole pairs bldc motor

philip_drake — Wed, 19 Dec 2018 22:42:25 GMT

To verify the setup I duplicated your set up on my desk and was able to use the KV BLDC reference solution with Freemaster and turn the motor. See the Reference Design Guide

1) go to 3-Phase Brushless DC Motor Control Design|NXP

2) do to the software/tools tab and download the Reference Design from https://www.nxp.com/downloads/en/reference-applications/MCRSP_BLDC_V1.3.0.exe

Download Freemaster tool --> here

3) run the BLDC and Freemaster installers

4) browse to the application using the KV10 FRDM board. C:\NXP\MCRSP_BLDC_V1.3.0\build_ref_solutions\frdmkv10z\iar

5) open the project

6) change the MCU target to KV11Z128

7) change the debug interface to P&E

8) download the application to the board, you can close the debug session.

9) run the application

10) if you press SW3 the motor may spin some but it has yet to be tuned

11) open the freemaster tool and from the tool open the project file at C:\NXP\MCRSP_BLDC_V1.3.0\freemaster

12) run the connection wizard connecting to the uart that the debugger provides

13) connect to the running project

14) MCAT is the parameter tuning tool and is incorporated into the reference solution and Freemaster -->Open the Parameters Tab to update the PP count and any other parameter and the Update Target

15) you can then test the operation by going to the App Control tab and BLDC Sensorless in the project Tree in the left panel.

16) click on RUN and try to spin the motor.

I hope this helps.

Happy Motoring.

Philip Drake

Re: How to calculate the Motor Parameters for 6 pole pairs bldc motor

haarism19 — Thu, 20 Dec 2018 12:10:06 GMT

Hi Philip Drake,

Thank you very much for the guided help, I was successfully able to use FreeMaster and change the PP count to 6 in my MCAT tool.

But my Emax RS1106 motor is still not spinning. The Emax RS1106 motor documentation provides the number of magnets as "9N12P" (link) which means 12 permanent magnets on the rotor and that means 6 polar pairs. So I can't figure out what other parameters I need to change to get my motor start working. What other parameters could majorly affect my motor?

Thank you,

Haaris

Re: How to calculate the Motor Parameters for 6 pole pairs bldc motor

philip_drake — Thu, 20 Dec 2018 18:16:02 GMT

It's good to hear you were able to get to Freemaster and MCAT.

There are notes on how to do parameter measurement here https://www.nxp.com/docs/en/application-note/AN4870.pdf

Other MCAT docs are also available if you search for MCAT on the nxp.com site.

Now comes the part where I have to pass your questions off since I don't have the experience needed. pavelsustek can you help.

Good luck,

Philip

Re: How to calculate the Motor Parameters for 6 pole pairs bldc motor

Ben — Mon, 31 Dec 2018 08:11:30 GMT

Hello Haaris

I believe that it is an issue of correctly define the commutation states tables according to the truth tables that you can find in the motor mfg. documents.

As BLDC motors are easily damaged when putting high current without rotation, I usually checking them without connecting the phase lines (connecting only the supply to hall sensors and sensors feedback- in your case - 5 wires). Then you can slowly rotate the rotor manually, and debug the SW activity and phase outputs while sensors data is changed.

Hope it help...

Benny