Quote:
Originally Posted by MPaulHolmes
cts_casemod, "the motor is magnetically saturated while turning slowly." I'm using IdRef = IqRef, so very little throttle has a very small field, and very small quadrature component, which I am hoping won't lead to saturation. what control scheme does your controller use with respect to throttle commands? does throttle command speed?
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My last controller used a method derived from the V/Hz topology to achieve closed loop torque control.
The amplitude was set according to the rotor frequency and the slip was changed to produce torque, so even tough I wasn't commanding full torque there was "full voltage" (as per V/Hz law) across the stator, generating losses if the motor was not fully loaded.
The new design is a hybrid. It can calculate the current slip and adjust both amplitude and stator frequency to achieve a given flux/torque, so it provides better control and higher efficiency.
I also added a speed ramp, such that in the event of a encoder fault, the maximum acceleration can be limited. The ramp is controlled by a few things:
Maximum allowable acceleration/deceleration rate;
Maximum current reached (this is different for Regen/Acc.)
Battery voltage below limit or BMS LVC warning
Battery voltage too high or BMS HVC warning