View Single Post
Old 10-21-2014, 09:41 AM   #1256 (permalink)
cts_casemod
EcoModding Apprentice
 
Join Date: Nov 2012
Location: East Midlands
Posts: 180
Thanks: 13
Thanked 81 Times in 52 Posts
Quote:
Originally Posted by MPaulHolmes View Post
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?
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
  Reply With Quote
The Following 2 Users Say Thank You to cts_casemod For This Useful Post:
e*clipse (10-21-2014), MPaulHolmes (10-21-2014)