Super Twisting based step-by-step observer for a DC series motor

In this paper, a super twisting based step-by-step observer for a DC series motor is proposed. In this context, an observability analysis is performed, revealing an observability singularity at zero current. In order to overcome this problem we propose the joint use of an estimator and an observer. The entire system is validated, by means of simulations, in the context of a sensorless speed control.