A method for detecting an indication of a possible blockage of a three-phase stepper motor by analyzing the motor current supply, comprising the following method steps: - impressing an operating current according to a current supply variant for the operation of the three-phase stepper motor into the one or more motor windings thereof which are either in star connection or in delta connection with virtual star point or without virtual star point by means of one switch half-bridge circuit per motor winding terminal, wherein the switch half-bridge circuit connects the motor winding terminal alternately to one of two supply voltage terminals of the motor winding, - commutating the motor windings by means of pulse width modulation of a sinusoidal or trapezoidal waveform of the operating current course, - wherein the current supply variant is modified such that shortly before a zero crossing of the current, i.e. with a residual current still remaining, at a motor winding terminal the latter is switched to high impedance for a specific period of time, but at least until the end of the time interval mentioned below, - detecting the voltage at a motor winding terminal switched to high impedance at least for the high-impedance time period and comparing said voltage to a threshold that is near the magnitude of the voltage at the one or the other of the two supply voltage terminals depending on the polarity of the voltage, - detecting the time period from when the motor winding terminal is switched to high impedance until the residual current is reduced to zero, by detecting the time interval for which the voltage at the motor winding terminal switched to high impedance crosses the threshold value, - comparing the length of the intervals for a plurality of motor winding terminals each switched to high impedance, and - detecting a possible blockage based on the comparisons of the lengths of the intervals by detecting alternating variations of the lengths of the time intervals by more than a predeterminable difference as an indication for a possible blockage. - impressing an operating current according to a current supply variant for the operation of the three-phase stepper motor into the one or more motor windings thereof which are either in star connection or in delta connection with virtual star point or without virtual star point by means of one switch half-bridge circuit per motor winding terminal, wherein the switch half-bridge circuit connects the motor winding terminal alternately to one of two supply voltage terminals of the motor winding, - commutating the motor windings by means of pulse width modulation of a sinusoidal or trapezoidal waveform of the operating current course, - wherein the current supply variant is modified such that shortly before a zero crossing of the current, i.e. with a residual current still remaining, at a motor winding terminal the latter is switched to high impedance for a specific period of time, but at least until the end of the time interval mentioned below, - detecting the voltage at a motor winding terminal switched to high impedance at least for the high-impedance time period and comparing said voltage to a threshold that is near the magnitude of the voltage at the one or the other of the two supply voltage terminals depending on the polarity of the voltage, - detecting the time period from when the motor winding terminal is switched to high impedance until the residual current is reduced to zero, by detecting the time interval for which the voltage at the motor winding terminal switched to high impedance crosses the threshold value, - comparing the length of the intervals for a plurality of motor winding terminals each switched to high impedance, and - detecting a possible blockage based on the comparisons of the lengths of the intervals by detecting alternating variations of the lengths of the time intervals by more than a predeterminable difference as an indication for a possible blockage.