Sliding Mode Observer

Farrokh Eshragi Azar

Other Parts Discussed in Thread: CONTROLSUITE

I am looking for a a detailed application note on the sliding mode observer (s) for a PMSM controller. My motor is in reality a linear motor and I would like to use a sensorless technique to control it. It will run at the equivalent of 60,000 rpms, and I would like to use a 28335 to control it. The current loop is already more or less working, but I need to close the speed loop. In doing so, I am not sure if the SMO will do its job. I certainly need to operate at a much higer ISR and PWM frequency than both the PFC and Dual Motor control kits which I have bought and which I have been able to get going with CCS V4. I would like to get a better understanding of the SMO to see if I can rely on 28335 or if I must go to a different processor.

Thank you

Farouk

over 14 years ago

0 ChrisClearman over 14 years ago

TI__Guru** 119670 points

Farrokh,

Here are several application notes, most of the sensorless deal with SMO.

http://focus.ti.com/general/docs/gencontent.tsp?contentId=67206

There is also documentation included with any of the Software downloads from here

http://focus.ti.com/general/docs/gencontent.tsp?contentId=67194#dmcs

For example, after installing controlSUITE (you can choose Custom install, High Voltage Kit if you don't want everything) the document here

C:\ti\controlSUITE\development_kits\HVMotorCtrl+PfcKit_v1.6\HVPM_Sensorless_2833x\~Docs

would talk about SMO and show how to use with F28335

There is also plenty of literature on SMO from industry, university, and google. SMO is jut one method for doing "sensorless" flux angle estimation.

0 Farrokh Eshragi Azar over 14 years ago in reply to ChrisClearman

Intellectual 780 points

Hi Chris,

Thanks for the links and the reply. I checked all the links and I have already seen the document under C:\ti\controlSUITE\development_kits\HVMotorCtrl+PfcKit_v1.6\HVPM_Sensorless_2833x\~Docs.

Neither one of these references address what I need. I would like to understand the theory behind the SMOPOS that is being used in the control suite to see if it would be a good fit with my motor. As I mentioned earlier, my motor is going to run at the equivalent of 60,000 RPMs and I can not stabilize the rotor angle that is returned by SMOPOS in order to close the speed loop reliably. When I change speed, the SMOPOS is not able to follow the angle any more and loses it. I understand there are different SMO setups that one can use as you too have suggested. But I prefer to explore what is provided in the ControlSuite where I have code for first. And it will be very helpful to understand the theory behind the algorithm before trying to figure out why it is not working properly. I don't see any apps notes that describe the theory. If you know of one, please point me in that direction.

Regards

Farouk