Method for the operation of a three-phase motor which is fed by two fig. 11, the two galvanically separated, electrically about 30 deg offset has three-phase stator windings

摘要

It is intended to specify a method for operation of a three-phase motor (3) which is supplied by two current intermediate-circuit converters (1, 2) and has two DC-isolated, three-phase stator windings (31, 32) which are offset through 30 DEG electrical and through which block-form currents having a current flow duration of 120 DEG flow during I-converter operation. According to the invention, direct converter operation is intended at low rotation speeds instead of I-converter operation, during which direct converter operation the two partial converters (1, 2) carry intermediate circuit currents (id1, id2) which are composed of sinusoidal sections. One of the intermediate circuit currents has a sinusoidal section profile which rises from sin (0 DEG ) to sin (30 DEG ) in a first interval of 30 DEG , while the other intermediate circuit current has a sinusoidal section profile which falls from sin (150 DEG ) to sin (180 DEG ). The sinusoidal section functions for the profile of the two intermediate circuit currents (id1, id2) are interchanged in the intervals which follow this and each have a duration of 30 DEG . The time period during which the valves are turned on within each period of the machine current is the same during direct converter operation as during I-converter operation, so that a smooth transition between the two operating modes is possible. IMAGE