How to drive Delta-connected motor with Sample project?

[菜緒西井]

Hello.

I use MC9S12ZVML128 PMSM Sensorless.

I try to use my own motor, and to modify the parameters in MCAT.

My motor is made with Delta connection, 

but the sample project is made for Y connection.

Then, I have some questions.

• Can I drive my motor with the sample project?
• Is it possible to input my motor parameters to MCAT without changing them?

　　(motor parameters=Rs,Ld,Lq etc.)

• Is there anything to pay attention when I drive my motor?

Best regards,

Nao

[pachamatej · Accepted solution]

Hello,

yes, you can drive a delta-connected motor using the same SW. All you need to do is to provide correct motor parameters relative to its terminals. I would recommend to measure the electric parameters as if it would be a start-connected motor. Please use https://www.nxp.com/docs/en/application-note/AN4680.pdf accordingly.

The main concern is the voltage - the terminal-to-terminal voltage is different for star and delta connections, which needs to be set correctly (since the SW works with the star connection). Please see the AN4680 terminology.

The performance should be nearly the same, however the theory says that some harmonics are "locked" in the delta loop, creating some additional losses. I would suggest to investigate the power losses using a power analyzer (while the mechanical load is measured or known). Further details can be found e.g. at IEEE Xplore digital library.

Regards

Matej

[nobuyuki_mihara]

Hello Matej,

I have an question about driving the delta connection motor drive.

I think that switching pattern is different delta connection and Y connection.
Do you not need to consider switching patterns?

Best Regards,

Nobuyuki Mihara

[pachamatej]

Hello,

Actually, this would be more academic question, but in general, the FOC is usually realized in D-Q frame (which acts as if a motor would be DC-motor). The Clarke and Park transform is used to go from this D-Q reference frame to three-phase A-B-C system and back to D-Q (for feedback signals). That means, if there would be any difference between the star and the delta connection, such transform would make it the same.

The only difference I see is the position of the rotor in reaction to a certain voltage vector. But again, considering a rotor position sensor and its linkage to the D-Q reference frame position, applying a D-axis voltage vector would make the rotor to align with the magnetic flux in both connection. If you would have these two motors next to each other, one star- and the other delta-connected, it might move the rotor to a different angle / real rotor position. But in terms of internal FOC "D-Q" frame and the rotor position seen by a sensor interface, it would be the same - the algorithm "sees" it the same.

Put in a simple words: there is no significant difference between star- or delta-connected motor field-oriented control.

What might be different is the flux and its harmonic components, but since you are probably investigating the motor already connected in the delta-connection, you would project these parameters again into D-Q frame. Mention the motor parameters, Rs, Ld and Lq (synchronous resistance and inductances) have to be measured in the configuration which will be used for the final application (parameters measured in star-connection cannot be used in delta-connected control and vice versa).

What IS definitely different is the voltage amplitude applied to the motor terminals to meet the nominal/maximal phase voltage, but as far as you probably have your motor designed for certain voltage, this would be no issue. 

I hope it helps,

Best regards,

Matej

[菜緒西井]

Hello, Matej.

Thank you for your reply.

It's helpful for me.

If there is something I can't understand, I will ask again.
I appreciate your continuous support.

Best regards,

Nao.