Fig. 9 shows the disturbance reaction of the position control loop. An especially critical situation for drives with encoder- less control is a load step during standstill. Fig. 9 shows the reaction of the drive on a load step from zero to rated load. The drive reacts in the same way as a servo drive with posi- tion encoder and controls the position deviation to zero. The control behaviour is comparable to a field oriented control with resolver feedback.