A NOVEL DIRECT TORQUE CONTROL OF AN INDUCTION MOTOR DRIVE WITH A THREE-LEVEL INVERTER

This paper presents a novel Direct Torque Control algorithm to be applied in induction motor electrical drives supplied by 3-level diode clamped inverters. It presents also a very simple algorithm for avoiding capacitor voltage unbalance. Results obtained with numerical simulations show that the employment of a 3-level inverter in such a control scheme permits to obtain the same dynamical performances as those obtained with a 2-level inverter with resulting far lower torque and flux ripples as well as a lower harmonic content in the stator current. Some considerations about the consequent benefits as for EMC of this drive are also presented.