TMS320F28069M: Improve QEP calibration

Robin Maubert

Hi TI team,

We are putting in place the sensored FOC capability, I am now using the following code for encoder initialization :

	// If we are forcing alignment, using the Rs Recalculation, align the eQEP angle with the rotor angle
	CTRL_Obj *obj = (CTRL_Obj *)mc_ctrlHandle;
	if (EST_getState(obj->estHandle) == EST_State_Rs)
	{
		ENC_setZeroOffset(mc_encHandle, (uint32_t)(qep_GetMaximumPositionCounter() - qep_GetPositionCounter()));
	}

how can we improve this step please ?

Thanks

over 6 years ago

0 Whitney Dewey over 6 years ago

TI__Guru 54445 points

What kind of improvement are you looking for? Is it not working as expected? Can you elaborate?

Whitney

0 Robin Maubert over 6 years ago in reply to Whitney Dewey

Intellectual 845 points

Hello,

I've been told that it is a temporary solution, how can we improve for long term ? Are we sure that setting a such 0 angle will always be working as expected ? Because we observe some cases where the motor does not start correctly just because of a bad angle setting.

Best

0 Whitney Dewey over 6 years ago in reply to Robin Maubert

TI__Guru 54445 points

I'm not sure what you're referring to when you say it's a temporary solution. Do you have any more context?

Is there a high load on the motor? Can you try increasing USER_MOTOR_RES_EST_CURRENT?

Thanks,

Whitney

0 Robin Maubert over 6 years ago in reply to Whitney Dewey

Intellectual 845 points

Hello,

I just wanted to know it there is a cleaner way to initialize the encoder 0 position than using the RsOffline feature with a high current to maintain the rotor and use the FOC sensorless angle before switching to sensored mode ?

Best

0 Whitney Dewey over 6 years ago in reply to Robin Maubert

TI__Guru 54445 points

No, this is the only method we have in our solutions. The only other thing I can think of is lab21 which demonstrates initial position detection, but the technique can only be used for certain salient PM motors.

Whitney

0 Robin Maubert over 6 years ago in reply to Whitney Dewey

Intellectual 845 points

Ok thanks for the note.

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TMS320F28069M: Improve QEP calibration