Victor, And your point is? A shunt motor control can achieve the speed torque range of an AC motor, although I would think the AC system is more efficient in this respect. I have designed brush DC, Sep-ex, compound wound, AC induction, BLDC systems, so I am familiar with the speed torque curves of all systems. My only point is the shunt system can perform similar to the AC system (although at lower RPM to a well designed AC motor that does not have a commutator). As Lee has pointed out before, the operation of each motor is similar although commutation of the DC system is mechanical while the AC motor is electronic (the inverter controls V/F). I'll admit I am a fan of AC systems, but the shunt motor is comparible in performance if designed properly. If I where to choose between the two I would definately take the AC system. Rod
Victor Tikhonov wrote: > Lee Hart wrote: > >>Rod Hower wrote: >> >>>> Motor rpm is limited by available Voltage. >>> >>>That applies to DC motors. Less common AC induction motors RPM is >>>dictated by the frequency generated by the inverter. >>> >>> >>>You can also do this with DC motors, it's called field weakening. >> >>Or, a series motor with a light load. No-load, they will run so fast >>that they can self-destruct! > > > Apply 100V to a DC motor with no load, it will do x RPM. > Apply 200V to it, and it will do 2x RPM. > > Apply any voltage to AC motor, and unless frequency is >0 > it will not run, load or no load. > > That is the difference. > > >>To be strictly correct, motor rpm is indirectly limited by voltage for >>all motors -- AC or DC. > > > More strictly - voltage limited from the high RPM side. > > Victor > > >>-- >>Lee A. Hart Ring the bells that still can ring >>814 8th Ave. N. Forget your perfect offering >>Sartell, MN 56377 USA There is a crack in everything >>leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen > > >
