Direct Torque Control of Induction Motors with Stator Flux Correction Applied to the Low-floor Tramcars

The paper presents a modified direct torque control (DTC) method of an induction motor, which is applied in the main drive of the low-floor tramcars series TMK2200 manufactured by the Croatian consortium CROTRAM — Koncar d.d., TŽV Gredelj d.d. and Đuro Đakovic d.d. The modification consists in the correction of stator flux vector by means of appropriate stator current component. Simplicity of the basic DTC is maintained because the only required machine parameter is stator resistance, yet the method enables stable operation in the whole speed range (including standstill). In comparison with other DTC schemes, the proposed method is more reliable because the rotor parameters are not used and the rotor quantities are not calculated. The method has been fully verified through exploitation of vehicles, and the simulation results are compared with the experiments on the laboratory model of the drive.