Approximation of transient torque response of a traction drive controlled by Indirect Stator-Quantities Control (ISC)

The dynamic control of four-quadrant line-side converter supplying the inverter-fed induction machines operating in single-phase 16.7-Hz railway applications is a major concern. Because of the low grid frequency the time-variant control margin is especially limited. To reduce the demand on the converter control in case of load changes, the DC-load current is predicted by a parameter-dependent fourth-order time-delay element. This paper gives a short introduction to the test bench used for railway grid-interaction analysis. Furthermore the stator-flux-based indirect Stator-Quantities Control (ISC) of induction machines as well as the derivation of the dynamic torque response and the resulting DC-load current are described. The excellent operation of the approximation is verified by simulation adjusted to measurement results.