Control of rotor flux in AC tram drive during sudden braking operation

The paper focuses on the behavior of the rotor flux indirect control system for an inverter fed AC tram drive. The control strategy used in this drive is based on the original state stimulator concept and has been applied in several modernized trams and in a trolley-bus in Poland. In these vehicles some oscillations of the modulus of the rotor flux vector during sudden braking operation were observed. The phenomenon of oscillations was tested in laboratory stand with adequate physical model of real tram drive as well as in a computer simulation model. These research allowed to explain the nature of the oscillations and to find some way to improve the control quality.