A rotary current machine system and method for controlling an electric rotary current machine, in particular an induction machine, having a rotor, a stator and at least two phase windings is disclosed. At least one electrical signal, in particular a voltage signal, is applied to at least one phase winding, preferably all phase windings, of the rotary current machine, and the current waveform in the at least one phase winding is measured. An intermodulation signal component, induced in the rotary current machine by slotting effects and magnetic saturation effects, which is determined from the current waveform measured in the at least one phase winding, is used for controlling the rotary current machine.

A rotary current machine system and method for controlling an electric rotary current machine, in particular an induction machine, having a rotor, a stator and at least two phase windings is disclosed. At least one electrical signal, in particular a voltage signal, is applied to at least one phase winding, preferably all phase windings, of the rotary current machine, and the current waveform in the at least one phase winding is measured. An intermodulation signal component, induced in the rotary current machine by slotting effects and magnetic saturation effects, which is determined from the current waveform measured in the at least one phase winding, is used for controlling the rotary current machine.

A control unit for operating an electrical machine which includes a rotor, a stator, and power electronics. The power electronics have a plurality of switching elements, by which the phases of the stator winding are connected/connectible electrically to an electrical energy store. The control unit includes first and second processing units and is configured to determine control signals for controlling the switching elements, using the processing units. The first processing unit is configured to determine a magnitude of a setpoint voltage vector for the phases based on a setpoint rotational speed of the rotor and an actual rotational speed of the rotor. The second processing unit is connected to the first processing unit so as to be able to communicate with it, and being configured to determine the control signals as a function of the magnitude of the setpoint voltage vector and an actual angle of rotation of the rotor.

A control unit for operating an electrical machine which includes a rotor, a stator, and power electronics. The power electronics have a plurality of switching elements, by which the phases of the stator winding are connected/connectible electrically to an electrical energy store. The control unit includes first and second processing units and is configured to determine control signals for controlling the switching elements, using the processing units. The first processing unit is configured to determine a magnitude of a setpoint voltage vector for the phases based on a setpoint rotational speed of the rotor and an actual rotational speed of the rotor. The second processing unit is connected to the first processing unit so as to be able to communicate with it, and being configured to determine the control signals as a function of the magnitude of the setpoint voltage vector and an actual angle of rotation of the rotor.

A commutation error compensation method for an electric motor includes: when a rotor, that has not been corrected, in an electric motor rotates in a set direction, collecting a position signal and a three-phase current signal of the rotor, wherein the position signal of the rotor represents the rotation angle of the rotor; filtering processing on the three-phase current signal to obtain a fundamental component of the three-phase current signal, and determining a position error compensation signal of the electric motor on the basis of the fundamental component of the three-phase current signal; determining an ideal phase interval of the rotor according to the position error compensation signal and the position signal of the rotor; and determining an adjustment method for the rotor of the electric motor according to the ideal phase interval of the rotor, and commutating the rotor of the electric motor according to the adjustment method.

A commutation error compensation method for an electric motor includes: when a rotor, that has not been corrected, in an electric motor rotates in a set direction, collecting a position signal and a three-phase current signal of the rotor, wherein the position signal of the rotor represents the rotation angle of the rotor; filtering processing on the three-phase current signal to obtain a fundamental component of the three-phase current signal, and determining a position error compensation signal of the electric motor on the basis of the fundamental component of the three-phase current signal; determining an ideal phase interval of the rotor according to the position error compensation signal and the position signal of the rotor; and determining an adjustment method for the rotor of the electric motor according to the ideal phase interval of the rotor, and commutating the rotor of the electric motor according to the adjustment method.

A compressor and a control method thereof are provided. The compressor includes a motor with a rotor of a permanent magnet. According to embodiments, the method of controlling the compressor includes: applying a detection current to the motor in response to a command of starting the compressor; detecting whether there is demagnetization of the permanent magnet of the rotor according to a response of the motor to the applied detection current; resetting an operating parameter of the compressor if there is the demagnetization; and starting the compressor according to the reset operating parameters. According to embodiments of the present disclosure, when the compressor is to be started, demagnetization is detected first, and the operating parameter are set accordingly, so as to suppress or avoid performance degeneration due to the demagnetization.

A compressor and a control method thereof are provided. The compressor includes a motor with a rotor of a permanent magnet. According to embodiments, the method of controlling the compressor includes: applying a detection current to the motor in response to a command of starting the compressor; detecting whether there is demagnetization of the permanent magnet of the rotor according to a response of the motor to the applied detection current; resetting an operating parameter of the compressor if there is the demagnetization; and starting the compressor according to the reset operating parameters. According to embodiments of the present disclosure, when the compressor is to be started, demagnetization is detected first, and the operating parameter are set accordingly, so as to suppress or avoid performance degeneration due to the demagnetization.

A system and method for controlling an electric machine via an inverter comprises an speed estimator that is configured to estimate a rotor speed of an electric motor to determine whether to control the inverter to operate the electric motor in a first mode or a second mode. For example, the first mode comprises a current-frequency control mode and the second mode comprises a back electromagnetic force (BEMF) mode. An electronic data processor or controller is configured to determine a first (current) command associated with a first mode of operating the electric motor, if the estimated rotor speed is a less than a speed threshold. The electronic data processor or controller is configured to determine a second (current) command associated with a second mode of operating the electric motor if the estimated rotor speed is equal to or greater than the speed threshold.

A system and method for controlling an electric machine via an inverter comprises an speed estimator that is configured to estimate a rotor speed of an electric motor to determine whether to control the inverter to operate the electric motor in a first mode or a second mode. For example, the first mode comprises a current-frequency control mode and the second mode comprises a back electromagnetic force (BEMF) mode. An electronic data processor or controller is configured to determine a first (current) command associated with a first mode of operating the electric motor, if the estimated rotor speed is a less than a speed threshold. The electronic data processor or controller is configured to determine a second (current) command associated with a second mode of operating the electric motor if the estimated rotor speed is equal to or greater than the speed threshold.