Device for operating a synchronous machine (PMSM) with a stator, which is assigned three winding phases, and a rotor, characterized in that the device is designed - to determine a setpoint value (I d,REF ) of a magnetic field-forming current in a coordinate system rotating with the rotor of the synchronous machine (PMSM), dependent on a magnetic field-forming raw setpoint current component (I d,RefAux ) of the rotor-circulating coordinate system and a magnetic field-forming current limit (I d,MAX ) of the rotor-circulating coordinate system, and to do so such that the setpoint value (I d,REF ) of the magnetic field-forming current is limited to the magnetic field-forming current limit (I d,max ), wherein the magnitude of the magnetic field-forming current limit (I d,MAX ) lies below a stability limit typical for the synchronous machine (PMSM) in the field weakening mode and - to reduce the magnitude of a torque-forming current limit (I q,MAX ) of the rotor-circulating coordinate system in the region of the limitation of the setpoint value (I d,REF ) of the magnetic field-forming current, dependent on the magnetic field-forming raw setpoint current component (I d,RefAux ) and the magnetic field-forming current limit (I d,MAX ), wherein - the device comprises a first controller (B17), which is designed to determine, dependent on a setpoint value (V d ) of a magnetic field-forming voltage of the rotor-circulating coordinate system and a setpoint value (V q ) of a torque-forming voltage of the rotor-circulating coordinate system, a magnetic field-forming intermediate raw setpoint current component (I d,IntRefAux ), dependent on which the magnetic field-forming raw setpoint current component (I d,RefAux ) is determined. - to determine a setpoint value (I d,REF ) of a magnetic field-forming current in a coordinate system rotating with the rotor of the synchronous machine (PMSM), dependent on a magnetic field-forming raw setpoint current component (I d,RefAux ) of the rotor-circulating coordinate system and a magnetic field-forming current limit (I d,MAX ) of the rotor-circulating coordinate system, and to do so such that the setpoint value (I d,REF ) of the magnetic field-forming current is limited to the magnetic field-forming current limit (I d,max ), wherein the magnitude of the magnetic field-forming current limit (I d,MAX ) lies below a stability limit typical for the synchronous machine (PMSM) in the field weakening mode and - to reduce the magnitude of a torque-forming current limit (I q,MAX ) of the rotor-circulating coordinate system in the region of the limitation of the setpoint value (I d,REF ) of the magnetic field-forming current, dependent on the magnetic field-forming raw setpoint current component (I d,RefAux ) and the magnetic field-forming current limit (I d,MAX ), wherein - the device comprises a first controller (B17), which is designed to determine, dependent on a setpoint value (V d ) of a magnetic field-forming voltage of the rotor-circulating coordinate system and a setpoint value (V q ) of a torque-forming voltage of the rotor-circulating coordinate system, a magnetic field-forming intermediate raw setpoint current component (I d,IntRefAux ), dependent on which the magnetic field-forming raw setpoint current component (I d,RefAux ) is determined. <EOS>