Abstract: For establishing the field direction without mechanical pickup upon startup of a rotating field machine, e.g., in permanent excitation, a high-frequency component (iz*) is impressed on the stator current or on the stator voltage. Thereby high-frequency voltage components (or current components) are coupled into the stator windings, the envelope curves of which are correlated to the position of the field axis of rotor axis. Preferably the components of a model vector (FM) which also contain high-frequency components are calculated by a flux computer (60). The high frequency components isolated in a filter (61) are correlated in a means value former (62) to the components of the direction vector (fx). Thereby a field-oriented operation of a synchronous machine is possible.

Abstract: A system for forming address signals which address respective converter switches in a frequency converter. The frequency converter is of the type wherein a DC voltage is provided for supplying electrical energy to phase outputs thereof in response to the states of the converter switches. In accordance with the invention, the phase output voltages, phase output currents, and predetermined desired phase currents are treated as space vectors from which are generated control difference space vectors. In one embodiment, a trigger pulse is generated externally and may be suppressed when the control difference vector has a value which is below a preselected tolerance limit. In a further embodiment, the trigger pulse is generated internally and is suppressed if the tolerance limit is exceeded. Upon the occurrence of each trigger pulse, a voltage space vector is addressed having a direction which is opposite to the control difference space vector.

Abstract: A system for forming addressing signals for addressing respective converter switches of a frequency converter; the frequency converter being of the type which is provided with DC input terminals for receiving electrical energy which is conducted to phase output terminals when the converter switches are operated in response to the addressing signals. Each of the combinations of converter switches is associated with a discrete space vector, and a load voltage vector is determined. In operation, two of the discrete space vectors which are adjacent to the voltage space vector are addressed for respective dwell times which correspond to the components of the voltage space vector as impressed upon the adjacent discrete space vectors. Either prior to or after the addressing of the adjacent discrete space vectors within a switching cycle, a short circuit state is addressed. In one embodiment, the order in which the adjacent discrete space vectors are addressed is reversed for each subsequent switching cycle.