DTC controlled PMSM traction drive input LC filter stabilization using model predictive control

This paper describes a new method for active damping of an input LC filter in traction drives supplied from dc catenary. Specifically, there is described the configuration of a traction drive with a surface mounted permanent magnet synchronous motor controlled by a direct torque control algorithm which is supplied via trolley-wire LC filter from a dc catenary. Because input LC filters are naturally nearly undamped and dangerous voltage oscillation can appear in the circuit, a new method for dc-link voltage stabilization is proposed. This method uses model predictive control for correction of traction drive operating point (demanded motor torque) which leads to the capacitor voltage stabilization and hence, improvement of the drive stability. The proper function of the stabilization (damping) effect of the proposed method is evaluated by a special frequency characteristic measurement which we proposed particularly for traction drives connected to a dc catenary. This paper also offers a comparison of our approach with the most frequently used damping method in traction drives. The behaviour of the DTC controlled PMSM drive has been verified by experiments on a down-scale laboratory prototype of the traction drive with rated power of 10.7 kW as well as the frequency characteristics measurement of this drive has been performed and evaluated.