This series field is what Thermite advocates leaving out in post #68 on this thread. I’m just wondering if anyone has tried to include it per factory original.
PM has a Medium-length thread on that several YEARS ago as explored "the ways" including use of a packaged FWB rectifer to insure its polarity was the right way when run in reverse.
There's two main tribes - compounded shunt and compensated shunt but variations within each as to how implemented.
Long story short? As a 6 HP "4Q" drive the SSDs have sensors and reserve to deliver fast and stable response to loads as don't need the help and don't need to fight it, either.
Compare the SSD regulation figures., over which relative RPM range, between internal IR sensing and use with a tachogenerator for feedback.
Note that the tacho signal, when used, goes into the same Op Amp .The rest of the drive has the merit to hold the better figure already. Tacho just enables it to "see better".