Method for monitoring a drive system comprising an inverter, which comprises a controller for the flux-generating current portion of a motor current space vector, an electric motor, in particular a three-phase motor, fed by the inverter, first signal electronics, an angular position sensor connected to the rotor of the electric motor, and current sensors for detecting the current flowing in a particular motor phase, wherein the measured values detected by the current sensors for detecting motor phase currents are supplied to at least the first signal electronics in the form of in particular a low-pass filtered digital data stream, wherein the first signal electronics generate, in particular by means of a means, a test signal that is periodic with a test frequency and is added to a setpoint, wherein a control deviation is the difference between the aggregate signal, generated out of the test signal and the setpoint, and an actual value, generated out of the measured values and a signal from the angular position sensor, of the flux-generating portion of the motor current space vector, in particular a motor current space vector shown in a rotor-fixed coordinate system, wherein the inverter provides the electric motor with such a voltage, in particular a voltage generated in a pulse-width-modulated manner, that the actual value is controlled towards the aggregate signal, wherein, by means of the first signal electronics, the components of the actual value of the motor current space vector are determined in a rotor-fixed coordinate system out of the detected measured values using the angular positions of the rotor of the electric motor that are detected by the angular position sensor, characterised in that the portion, present at the test frequency, of the component of the actual value of the motor current space vector in the direction of the flux-generating current portion is determined and monitored for an impermissibly large deviation from a predetermined range, wherein a fault signal is triggered, relayed and/or displayed if the permitted deviation from the predetermined range is exceeded, wherein the component determined in the direction of the torque-generating current portion is monitored for an impermissibly high level of deviation from zero, wherein the voltage provided to the electric motor by the inverter is added to a test voltage, which is configured as an AC voltage, and it is monitored whether the current driven by the test voltage has, in a first motor phase, a detected current portion that is identical in magnitude to the current portion detected in a second motor phase but with the opposite sign, and whether, in the third motor phase, it has no detected current portion, wherein it is monitored whether the curve of the motor voltage simultaneously has a voltage jump at a or each zero crossing of the motor current. wherein the measured values detected by the current sensors for detecting motor phase currents are supplied to at least the first signal electronics in the form of in particular a low-pass filtered digital data stream, wherein the first signal electronics generate, in particular by means of a means, a test signal that is periodic with a test frequency and is added to a setpoint, wherein a control deviation is the difference between the aggregate signal, generated out of the test signal and the setpoint, and an actual value, generated out of the measured values and a signal from the angular position sensor, of the flux-generating portion of the motor current space vector, in particular a motor current space vector shown in a rotor-fixed coordinate system, wherein the inverter provides the electric motor with such a voltage, in particular a voltage generated in a pulse-width-modulated manner, that the actual value is controlled towards the aggregate signal, wherein, by means of the first signal electronics, the components of the actual value of the motor current space vector are determined in a rotor-fixed coordinate system out of the detected measured values using the angular positions of the rotor of the electric motor that are detected by the angular position sensor, characterised in that the portion, present at the test frequency, of the component of the actual value of the motor current space vector in the direction of the flux-generating current portion is determined and monitored for an impermissibly large deviation from a predetermined range, wherein a fault signal is triggered, relayed and/or displayed if the permitted deviation from the predetermined range is exceeded, wherein the component determined in the direction of the torque-generating current portion is monitored for an impermissibly high level of deviation from zero, wherein the voltage provided to the electric motor by the inverter is added to a test voltage, which is configured as an AC voltage, and it is monitored whether the current driven by the test voltage has, in a first motor phase, a detected current portion that is identical in magnitude to the current portion detected in a second motor phase but with the opposite sign, and whether, in the third motor phase, it has no detected current portion, wherein it is monitored whether the curve of the motor voltage simultaneously has a voltage jump at a or each zero crossing of the motor current.