Modified Joensson-type control scheme for AC induction motors

A modified Joensson-type control scheme for an AC induction motor is presented. It is very simple, due to the voltage control, since only shaft speed measurement is required. The control scheme allows the torque and the phase current to be limited in a simple way by limiting the commanded slip frequency. Therefore, the main disadvantage of the original Joensson-type control scheme is eliminated, since the limitation of the torque and the phase current is not possible with the original scheme. Experimental results confirming the good dynamic behavior of the modified Joensson-type control scheme are also shown