A low-cost three-level converter for low-power electrical drives with induction motor applied to direct torque control

This paper presents the realization of a low-cost low-power 3-level inverter for electrical drives with induction machines controlled by a new DTC algorithm. The adopted DTC scheme employs a suitably devised voltage balancing algorithm which maintains constant the voltages across the DC link capacitors. In particular, a prototype of a 3-level inverter, both in its signal and power stages, has been built and experimentally verified in a DTC drive with an induction motor. This work shows the detailed description of the new DTC control algorithm for a 3-level inverter and of the voltage balancing algorithm. Moreover the main stages of the inverter itself and the corresponding circuit schemes are described. The experimental results show the practical feasibility of the proposed high performance drive solution.