TMS320F28027F: How to enable force angle startup in instaspin-foc?

Hey Sean,

So is it the same for instaspin-FOC project? 

For FOC example, there is no SPIN TAC, what is the point to connect after  uses force angle to provide initial angle estimate?

Hi Sean,

Thanks. How to know the back-EMF is enough for running FAST successfully? I think I can tuning the point for my system.

The answer is dependent on your feedback circuitry, which will determine effective number of bits (ENOB) for your ADC. Once you've realized the minimum resolution, you can determine the realistic bemf signal necessary for accurate reproduction of the flux angle

Sean

Hi Sean,

I think I could tuning the exact point based on my boards or motor, but can you please let me know the condition of enough bemf? Just check weather there is enough phase current, or any other condition?

if ((phase current > point_a)&&(condition2))...
{
//Hand off force angle
}

I'm sorry, there is no defined limit where the bemf signal is strong enough to ensure reliable sensorless control

Sean

Hi Sean,

Thanks for your reply. I think you may misunderstanding the my request, what I want to know is the general rules that could be used to decide when the force angle could be hand off to estimator instead of exact point or defined limit. This would be helpful for me to debug, can you please help on this?

Hi Sean,

May I get your further comments on this? Thanks...

Jack

My best suggestion would be to determine it experimentally with your motor. Spin the motor up to load/speed such that the output waveform looks good, and then step the load/speed back until the waveform starts to falter due to insufficient back-EMF. You should be able to find a good transition period using that method. Somewhere in the 5% load range, depending on how your board's feedback circuitry is designed, and how clean the signal is

Sean