The torque output of the angular velocity control is limited to avoid significant dynamics around zero speed and for negative speeds. Since the electric machine is operated as generator, the mechanical power is negative. The generator is operated at positive angular speed w and thus torque tau is negative. Torque limitation, however, is implemented as function of speed. The characteristic of the torque limiter is shown the figure below for tauRef = 10kNm. However, In the investigated case the reference speed wRef = 50*pi rad/s. For positive speeds greater than linear = 2% of the reference speed the torque is not limited. The range between zero angular speed and 2% of the reference speed torque is limited by the steep linear curve shown in the figure below. In the negative speed range - which shall never be reached - torque is limited linearly towards the negative reference angular velocity. In the vicinity of zero speed torque is limited by limit = 2% with respect to tauRef.

Torque limitation as function of angular velocity

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