Method for determining rotor position of electric motor, elevator and electrical converter unit

An elevator comprising

• an elevator car,
• an elevator motor configured to move the elevator car,
• an electrical converter unit for operating the elevator motor,
• at least one elevator brake, and
• a control unit configured at least to cause the elevator, preferably the electrical converter unit thereof, to:
• supply a first excitation signal, such as a first excitation voltage or current signal, to the elevator motor,
• determine a first response signal, such as a first response current or voltage, respectively, generated in the elevator motor in response to the first excitation signal;
• wherein the elevator is further configured to
• determine, based on the first response signal, an electrical angle of a direct axis of the electric motor with respect to a stationary reference frame, such as related to a stator of the electric motor,
• supply a second excitation signal, such as a second excitation voltage or current signal, to the electric motor, wherein the second excitation signal is based on the determined electrical angle,
• determine a second response signal, such as a second response current or voltage, respectively, generated in the electric motor in response to the second excitation signal, and
• determine the rotor position based on the second response current.

An electrical converter unit configured to

• supply a first excitation signal, such as a first excitation voltage or current signal, to the elevator motor,
• determine a first response signal, such as a first response current or voltage, respectively, generated in the elevator motor in response to the first excitation signal;
• wherein the electrical converter unit is further configured to
• determine, based on the first response signal, an electrical angle of a direct axis of the electric motor with respect to a stationary reference frame, such as related to a stator of the electric motor,
• supply a second excitation signal, such as a second excitation voltage or current signal, to the electric motor, wherein the second excitation signal is based on the determined electrical angle,
• determine a second response signal, such as a second response current or voltage, respectively, generated in the electric motor in response to the second excitation signal, and
• determine the rotor position based on the second response signal.