Abstract: A method for starting a sensorless single-phase electric motor. The electric motor includes a permanent magnetic motor rotor, an electromagnetic motor stator having a stator coil, a power electronics which energizes the stator coil, a current sensor which measures a current flowing in the stator coil, and a control electronics which controls the power electronics. The control electronics is connected with the current sensor. The method includes energizing the stator coil with an alternating drive voltage, monitoring a drive current which is generated in the stator coil by the alternating drive voltage, and commutating the alternating drive voltage whenever the drive current reaches a predefined positive current threshold value or a predefined negative current threshold value.

Abstract: A method for driving a single-phase electric motor includes switching drive electronics to a first on-state during a first on-time interval of a pulse width modulation period, switching the drive electronics to a second on-state during a second on-time interval of the pulse width modulation period, switching the drive electronics to an off-state between the first and second on-time intervals, and measuring the phase current with a current sensor. The first and the second on-time interval of one pulse width modulation period are provided with different interval lengths if a defined effective duty cycle is lower than a first duty cycle threshold value so that one of the first and the second on-time interval has an interval length which is equal to or larger than a defined minimum on-time interval length. The phase current is measured during the first and/or second on-time interval with the defined minimum on-time interval length.

Abstract: A method for starting a sensorless single-phase electric motor. The electric motor includes a permanent magnetic motor rotor, an electromagnetic motor stator having a stator coil, a power electronics which energizes the stator coil, a current sensor which measures a current flowing in the stator coil, and a control electronics which controls the power electronics. The control electronics is connected with the current sensor. The method includes energizing the stator coil with an alternating drive voltage, monitoring a drive current which is generated in the stator coil by the alternating drive voltage, and commutating the alternating drive voltage whenever the drive current reaches a predefined positive current threshold value or a predefined negative current threshold value.