Method for operating a drive system, and drive system

A method for operating a drive system, wherein the drive system has:

• a three-phase motor, having:
• a shaft,
• a first three-phase stator winding which is to be connected to a three-phase AC voltage grid,
• a second three-phase stator winding which is to be connected to the three-phase AC voltage grid in such a way that a second stator rotating field rotating in opposition results with respect to a first stator rotating field which is generated by the first stator winding, and
• a rotor winding system which is mechanically coupled in a rotationally fixed manner to the shaft, and
• at least one inverter which is mechanically coupled in a rotationally fixed manner to the shaft and which is electrically coupled to the rotor winding system, wherein the at least one inverter is configured to generate actuation signals for the rotor winding system, the method comprising the steps of:
• generating the actuating signals such that a first rotor rotating field and a second rotor rotating field rotating in opposition to the first rotor rotating field are generated, wherein
• the generating of the actuation signals for the rotor winding system solely depend on signals detected on the rotor side, wherein
• the signals detected on the rotor side comprise rotor voltages of the rotor winding system,
• the rotor voltages of the rotor winding system are measured in a zero-current state of the rotor winding system, wherein values of an instantaneous grid voltage amplitude, an instantaneous grid frequency, an instantaneous rotor rotation speed, and/or an instantaneous rotor position angle are ascertained based on a time profile of the rotor voltages.

A drive system, comprising:

• a three-phase motor, comprising:
• a shaft,
• a first three-phase stator winding which is to be connected to a three-phase AC voltage grid,
• a second three-phase stator winding which is to be connected to the three-phase AC voltage grid in such a way that a second stator rotating field rotating in opposition results with respect to a first stator rotating field which is generated by the first stator winding, and
• a rotor winding system which is mechanically coupled in a rotationally fixed manner to the shaft, and
• at least one inverter which is mechanically coupled in a rotationally fixed manner to the shaft and which is electrically coupled to the rotor winding system, wherein the at least one inverter is configured to generate actuation signals for the rotor winding system such that a first rotor rotating field and a second rotor rotating field rotating in opposition to the first rotor rotating field are generated,
• wherein the at least one inverter is configured to generate the actuation signals for the rotor winding system solely depending on signals detected on the rotor side,
• wherein the signals detected on the rotor side comprise phase current signals of the rotor winding system,
• wherein the phase current signals detected on the rotor side are divided by calculation into first components, which belong to the first rotor rotating field, and into second components, which belong to the second rotor rotating field, and
• wherein the phase current signals which are associated with the first rotor rotating field and with the second rotor rotating field by means of the division by calculation are divided by calculation into symmetrical components with co-rotating and counter-rotating components given an asymmetrical time profile of the three-phase AC voltage grid.