What is the limitation of a three phase AC induction motor?
The AC motor was originally a fixed speed machine running at typically 1440 rpm on 50Hz. It runs that the frequency of the supply more or less. In the middle 1980's, the electronic drives companies (Control Techniques, Hitachi, Siemens, Asea etc) started to develop variable speed drives that made the AC motor much more versatile. The fixed speed motor could now be controlled. The technology developed into 3 typical product ranges. The open loop inverter was the cheapest to make and is good for fans and pumps etc. Open loop vector control is more expensive but the performance is much better and particularly at low RPM. The most expensive but the best product is closed loop vector which emulates the performance of the DC motor in an AC motor. Now the AC motor only limitation is speed. Special AC motors are used on CNC Machine tools at 20,000 rpm So if the motor is made right there is very little that the AC motor cannot do! Hope this hleps you
