DTC of reconfigured three level inverter fed IM drives following a leg failure

Abstract

Purpose

The purpose of this paper is to deal the adaptation of a direct torque control (DTC) strategy, originally dedicated to three level three leg inverter fed induction motor (IM) drives, following a leg failure that required the reconfiguration of the inverter from three to two legs.

Design/methodology/approach

In case of troubles with one leg of a three level inverter, it is interesting in some applications to keep operating using the two remaining legs. So, after the detection and isolation of the faulty leg, the drive connection should be rearranged with the connection of the motor phase, previously linked to the faulty leg, to the mid point of the DC-bus voltage, leading to a three level two leg inverter topology (also called bridge B8-inverter).

Findings

It has been found that the IM drive exhibits better performances under the proposed DTC strategy dedicated to the reconfigured inverter than those yielded by the DTC of the IM drive under healthy operation of the inverter. It has been noticed that the only drawback affecting the reconfigured inverter fed IM drive is the speed range limitation.

Research limitations/implications

This work should be extended by an experimental validation of the proposed DTC strategies.

Originality/value

The power factor of the reconfigured three level inverter fed IM drive is higher than the one yielded by the three level three leg inverter fed one. This represents a crucial cost benefit.

Citation

Gallah, T., Bouzidi, B. and Masmoudi, A. (2016), "DTC of reconfigured three level inverter fed IM drives following a leg failure", COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, Vol. 35 No. 2, pp. 764-781. https://doi.org/10.1108/COMPEL-12-2015-0451