Method for recording an initial rotational position of a rotor
AssigneeSchaeffler Technologies AG & Co. KG
InventorsErhard Hodrus, Christian Eberle, Alexander Rösch
Life of this patent
Estimating the term…
Abstract
A method for recording an initial rotational position of an at-rest rotor of an electric motor with respect to a stator by carrying out a current response recording in which a high-frequency injection signal is introduced along a recording direction in a dq coordinate system of the electric motor.
Claims14
A method for recording an initial rotational position of an at-rest rotor of an electric motor with respect to a stator, in that a current response recording is carried out, in which a high-frequency injection signal is introduced along a recording direction in a dq coordinate system of the electric motor and at least one current variable is recorded as a recording current variable as a current response to the injection signal, wherein;
- a first current response recording along a first recording direction as a presumed d-direction is carried out in which the injection signal is overlaid with a first constant current value in the first recording direction and the recording current variable is recorded as a first current recording value;
- a second current response recording is carried out along a second recording direction opposite to the first recording direction in which the injection signal is overlaid with a second constant current value in the second recording direction and the recording current variable is recorded as a second current recording value;
- and
- after the first and second current response recordings, a possible 180° offset between the first recording direction and the actual d-direction is established as a function of a ratio of the first and second current recording values, wherein a multi-angle current variable recording is carried out during the current response recording, in which, on the one hand, a current variable along a first direction offset by a first angle relative to the recording direction is detected as a first recorded current variable and, on the other hand, a current variable along a second direction offset by a second angle relative to the recording direction is detected as a second recorded current variable and the recording current variable is calculated as a function of first and second detected current magnitudes.
An electric motor system, comprising:
- a stator including at least one winding;
- a rotor mounted for rotation with respect to the stator;
- and
- a control unit operatively coupled to the at least one winding and configured to:
- while the rotor is at rest, inject a high-frequency signal along a first recording direction that follows a presumed d-axis that is presumed to coincide with an actual d-axis of a dq reference frame that has a fixed orientation relative to the rotor;
- superimpose a first constant current value on the high-frequency signal in the first recording direction and acquire, as a first recording value, a current response produced by the at least one winding;
- inject a high-frequency signal along a second recording direction that is 180 degrees offset from the first recording direction;
- superimpose a second constant current value in the second recording direction and acquire, as a second recording value, a current response produced by the at least one winding;
- compare an amplitude of the first current recording value with an amplitude of the second current recording value;
- and
- determine whether there is a possible 180 degree offset between the presumed d-axis and the actual d-axis of the rotor based on the comparison of the amplitudes.
Dependencies are inferred from the claim text.