Effect of Duration on Encoder Alignment

[JAM_1999]

 

Hello!

We are currently using the STSPIN32G4 microcontroller for our project, which incorporates a quadrature encoder.

In the start-up parameters, there are three key settings: Duration, Alignment Electrical Angle of Id, and Final Current Ramp value. We have determined the encoder alignment angle using the current waveform procedure.

Could you explain how altering the default values of Duration and Final Current Ramp will affect the system? Specifically, we are interested in understanding how these changes might impact the displacement of the rotor shaft during the encoder alignment process, and whether setting a shorter duration could be disadvantageous.

[GTOMA]

Posting the answer here for future reference:

 

Could you explain how altering the default values of Duration and Final Current Ramp will affect the system?

The duration is the time (t) and final current ramp is the current at t.
Prior to alignment, the rotor position is unknown.
A and B signals can only give a relative change in angle/speed and not absolute values. So, we will need some alignment (either manual or automated)

The automated method used to align the rotor is to set a Iq ramp for a fixed duration t. The alignment is considered complete once the Z signal interrupt is received by the controller.

 

Specifically, we are interested in understanding how these changes might impact the displacement of the rotor shaft during the encoder alignment process, and whether setting a shorter duration could be disadvantageous.

It depends on the load torque applied to the motor shaft during startup. If the motor is loaded, you’d want to have a larger Final Current value, so the shaft rotates enough to complete the encoder alignment. The duration parameter (t) can be steeper based on the rate of change of torque that is realistic for the shaft load-coupler.

[Rajeswari]

How to get encoder alignment angle using current waveform. can you let me know