Method and device for determining the rotor position of an electric motor with several motor strings

The method as recited in one of the preceding claims,

• wherein the electromotor (10) is supplied with current using pulse width modulation, the switch-on time points (te) for supplying current to the motor phase windings (101, 201, 301) of the electromotor (10) are defined by a pulse-width-modulation basic timing signal (42), and the determination of the at least one first polarity value (111, 211, 311) is synchronized on the basis of the pulse-width-modulation basic timing signal (42).

The method as recited in one of the preceding claims,

• wherein the at least one phase voltage (107, 207, 307) and/or the star-point voltage (25, 26) is simulated.

The method as recited in one of the preceding claims,

• wherein it is determined if the first motor phase winding (101, 201, 301) is not supplied with current, and the at least one first or second polarity value (111, 211, 311) is read out if the first motor phase winding (101, 201, 301) is not supplied with current.

A detection module for determining the rotor position of an electromotor (10) having a plurality of motor phase windings (101, 201, 301), in particular, a brushless DC motor, which has detection means for determining the polarity of at least one phase winding voltage (107, 207, 307) induced in at least one first motor phase winding (101, 201, 301), as at least one first polarity value (111, 211, 311), through comparison to a reference value, in particular, to a real or simulated star-point voltage (25, 26) applied at a star point of the motor phase winding (101, 201, 301),

• wherein the detection means for determining the at least one first polarity value (111, 211, 311) can be synchronized to a switch-on-time point (te) for supplying current to the at least one first or second motor phase winding (101, 201, 301), and the detection means are configured such that they can determine the at least one first polarity value (111, 211, 311) after a preestablished delay (twa), which follows the at least one switch-on time point (te).