Direct torque control with switching frequency limitation for three-level inverter-fed induction motors

A direct torque control algorithm with limited switching frequency for three-level inverter-fed induction motors is presented. With basic direct torque control, the switching frequency is variable and depends largely on induction motor parameters and flux and torque controllers hysteresis bands. To limit the maximum switching frequency, an algorithm for the verification of power switches commutation possibility and for the selection of voltage space vector is proposed. This algorithm is verified by simulation results.