Resolver sin and cos signal not perfect circuit from etpu output

[Harry0001]

I get the resolver feedback sin and cos signal and process them as the following imag,however it is not a perfect circuit.I get the sin and cos from the etpu module and its resolver output.Who can tell me how to adjust some parmeter to let it perfect circuit.Thanks!  

[Yongbing_Nan · Accepted solution]

Hi, 

This is an observation error, which is caused by the unequal ratio of the X axis and the Y axis. The radius of the unit circle in the figure below is equal. it's a perfect circle.

[Harry0001]

Thanks!Exactly!

[petervlna]

Hello,

For first look output from resolver seems like and ellipse then circle, but on the image there is evident difference in the axes diameters. The on eon X is not equal to one on Y axis.

There should be symmetric grid on both axis.

Another reason for experiencing such behavior is different gain of end stages for professing of signals of resolver.

Best regards,

Peter

[Harry0001]

Could you tell me the specify gain parameters which can be used to adjust the circuit shape?

[petervlna]

Hello,

Could you please specify which device and which eTPU library are you referring to?

Best regards,

Peter

[Harry0001]

MPC5777C
ETPU version 1.2
resolver_etpu version 1.75