Hi Chris,
I wasn't exactly sure where to post this question so I figured I would post it here. Please feel free to move it to the appropriate thread if necessary.
Subject: PMSM FOC using eQEP with Quadrature Incremental Rotary Encoder on TMS320F2802.
Concern: We want to use a quadrature incremental rotary encoder for FOC control of a permanent magnet synchronous motor (PMSM). However, this motor can run continuously and we are concerned about the FOC angle being off over time (months to years) due to loss or gain of a pulse and this error accumulating over time. Would using the Index pulse eliminate this error? Or do we then need to worry about not receiving an Index pulse. I was concerned about this advisory from Texas Instruments, “If the first index event at the QEPI input occurs at any time from one system clock cycle before the corresponding QEPA/B edge to two system clock cycles after the corresponding QEPA/B edge, then the eQEP module may miss this index event.” Do you have any industry experience with this? Can you provide some insight into this? Would we have to worry about field failures over time due to this possible issue?
Question: Is an index pulse from the encoder needed for FOC control of a PMSM motor? Without the index pulse would we have to worry about the accumulative error over time due to any possible loss or gain of encoder edges? Can you provide any details on solutions?
Thank you in advance for your help with this. I look forward to hearing back from you.
Best regards,
Bill Szatkiewicz
(954) 729-5541