Method and apparatus for setting holding current of motor

Abstract

The invention relates to a method for operating an at least three-phase electronically commutated electric machine (2) comprising a stator winding (3) with a plurality of phase lines (4) and a rotor (5), wherein the machine (2) is operated with block commutation by applying control potentials (V1, V2) generated in a pulse-width-modulated manner to phase terminals (7) for energizing the phase lines (4), the method comprising the step (S5) of detecting at least one measurement potential (M1, M2) occurring after applying a measurement pulse to one of the phase terminals (7); when the machine (2) is at standstill, maintaining the rotor (5) with respect to a load torque by means of a holding position control (S6), a control variable of the holding position control depending on or corresponding to the at least one measurement potential (M1, M2), and the holding position control designating the control potentials (V1, V2) of the block commutation as controlled variables.

Claims

1. A method for operating an at least three-phase electronically commutated electric machine (2) having a rotor (5) and a stator winding (3) having a plurality of phase lines (4), wherein, The method of operating the motor (2) by means of block commutation by applying control potentials (V1, V2) generated in a pulse width modulation manner to the phase terminals (7) for energizing the phase line (4) includes: - Step (S5) to detect at least one measurement potential (M1, M2) that appears after a measurement pulse is applied to one of the phase terminals (7); - When the motor (2) stops, the step (S6) involves holding the rotor (5) against the load torque by means of a holding position control, wherein the control variable of the holding position control depends on or corresponds to the at least one measured potential (M1, M2), and the holding position control designates the control potential (V1, V2) of the block commutation as the controlled variable. Specifically, two measurement potentials (M1, M2) are detected based on the application of two opposite measurement pulses, and a measurement potential difference (R) is determined from the two measurement potentials (M1, M2). The hold position control receives the measurement potential difference (R) as the control variable. In order to stop the motor (2), the stator winding (3) is energized, causing the rotor (5) to stop in a stopping region (S) in a manner that resists the load torque. The stopping region (S) is located within an electrical position angle that has a predetermined safe distance to the maximum value of the measured potential difference (R). After stopping in the stop region (S), the control voltage, which is the difference between the applied control potentials (V1, V2), is continuously or gradually reduced in numerical value, causing the rotor to move in the direction of the applied load torque. It is determined whether the maximum or minimum value of the at least one measured potential (M1, M2) has been exceeded based on a curve of the electrical position angle during rotor movement. After determining that the maximum or minimum value of the measured potential has been exceeded, the holding position control is initiated.

2. The method of claim 1, wherein, The measurement pulse is formed as part of the pulse width modulation generation of the control potentials (V1, V2), or superimposed on the pulse width modulation generation of the control potentials (V1, V2).

3. The method of claim 1, wherein, In terms of time, within the pulse width modulation period, the two measurement potentials (M1, M2) are detected based on the application of two inverse measurement pulses.

4. The method according to claim 1, wherein, In order to stop the motor (2), the stator winding (3) is energized in an uncontrolled operation, so that the rotor (5) stops in the stop region (S) in a manner that resists the load torque.

5. The method according to claim 1, wherein, The stop region (S) is within a position angle range of 0° and + / -40°, wherein the electrical position angle of 0° corresponds to the alignment of the rotor poles with the energized stator teeth.

6. The method according to claim 5, wherein, The stop region (S) is located within a position angle range between 0° and + / -20°.

7. The method according to claim 1, wherein, The holding position control is configured such that the rotor of the motor (2) is adjusted to a holding position, which corresponds to a deviation angle between 60° and 85°.

8. The method according to claim 7, wherein, The holding position corresponds to a deviation angle between 70° and 80°.

9. The method according to claim 1, wherein, If the electrical position angle is determined to be numerically exceeded by the limit angle based on the measured potentials (M1, M2), or if the previously exceeded maximum / minimum value of the measured potential is exceeded again when the electrical position angle is numerically decreased, then the holding position control is terminated.

10. The method according to claim 1, wherein, When the position control is active, the existing reversing mode is maintained.

11. An apparatus for operating a motor (2) with at least three-phase electronic commutation, said motor comprising a rotor (5) and a stator winding (3) having a plurality of phase lines (4), wherein, The motor (2) is operated by block commutation by applying a control potential generated in a pulse-width modulation manner to the phase terminal (7) for energizing the phase line (4), wherein the device is configured to perform the method as described in any one of claims 1 to 10, and the device is configured to: - Detect at least one measurement potential that appears after a measurement pulse is applied to one of the phase terminals (7); - When the motor (2) stops, the rotor (5) is held in a manner against load torque by means of a holding position control, the control variable of the holding position control depending on or corresponding to the at least one measured potential, and the holding position control designates the control potential of the block commutation as the controlled variable.

12. The apparatus according to claim 11, wherein, The device is a control unit (9).

13. A motor (2) having at least three-phase electronic commutation and a system of the apparatus according to claim 11 or 12, the motor comprising a rotor (5) and a stator winding (3) having a plurality of phase lines (4).

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