leitmotif
Member
Want to use 3 phase motors to drive vehicle. One motor per wheel, each is independent of other except they are coupled by the road of course.
PROBLEM YOu want to turn at say 15 mph and it is a maximum turn. Speed is held constant at 15 mph. Speed differance between tires is 10%. One tire is 95% of speed and other is 105%.
May not be a problem in V/Hz mode but V/Hz is not an option because of starting difficulties. Let us assume torque boost is not an option.
So we are forced to do this in a speed feedback mode.
Vector (is it? I'm losing my term here) is not an option with two motors because VFD will not know which motor to believe.
Encoder would have to be used for speed feedback.
So in cornering if the motor with encoder is 105% VFD will keep trying to slow motors and if encodr is on motor with 95% speed VFD will try to speed both up.
Am I thinking this correctly?
CONCLUSION In this application control of two motors with one VFD just not a good idea.
Dan Bentler
PROBLEM YOu want to turn at say 15 mph and it is a maximum turn. Speed is held constant at 15 mph. Speed differance between tires is 10%. One tire is 95% of speed and other is 105%.
May not be a problem in V/Hz mode but V/Hz is not an option because of starting difficulties. Let us assume torque boost is not an option.
So we are forced to do this in a speed feedback mode.
Vector (is it? I'm losing my term here) is not an option with two motors because VFD will not know which motor to believe.
Encoder would have to be used for speed feedback.
So in cornering if the motor with encoder is 105% VFD will keep trying to slow motors and if encodr is on motor with 95% speed VFD will try to speed both up.
Am I thinking this correctly?
CONCLUSION In this application control of two motors with one VFD just not a good idea.
Dan Bentler