A modified torque control approach for load sharing application using V/F induction motor drives

The volt-per-Hertz (V/F) drives of induction motors (IMs) are widely used in industrial applications because these drives are simple and cost effective. V/F drives operation is based on speed command and unable to toque control. In industrial applications the IMs are coupled to feed heavy loads. Coupling the IMs in addition to economic advantage leads to reduction of energy consumption. When the load becomes heavier the number of IMs that feed the load will be increased and vice versa. However with coupled IMs, the load is not shared properly and some of the IMs may be overloaded. For a proportional load sharing using of the torque control drives seems to be necessary, but these drives are complicated and expensive. This paper describes a torque control approach for coupled IMs V/F drives which is accurate and inexpensive and also uses minimum number of motor parameters.