Abstract: A method for determining a saturation characteristic of a synchronous reluctance machine includes applying with a pulse inverter a voltage sequence to a stator of the synchronous reluctance machine, wherein the voltage sequence introduces stator fluxes and is applied such that torques acting on a rotor of the synchronous reluctance machine cancel each other out during the application of the voltage sequence. Electrical currents resulting from the stator fluxes are measured and the saturation characteristic is determined based on the stator fluxes and the measured electrical currents.

Abstract: A monitoring device for a reluctance machine includes a vector rotator for rotating a space phasor of the reluctance machine that depends on a voltage in a coordinate system that rotates with a negative fundamental frequency, a low-pass filter filtering the rotated space phasor and producing an output signal, and a signal evaluation device evaluating the output signal. A DC value of the produced output signal in the rotating coordinate system is monitored, and an error in operating the reluctance machine is identified when the DC value is above a predefined threshold value.

Abstract: In a method for operating an electric machine a first test signal is fed into the electric machine and a first response signal of the electric machine is measured. A first state variable for a rotor of a synchronous reluctance motor of the electric machine is determined as a function of the first response signal, and a second state variable for the rotor of the synchronous reluctance motor is determined. The first state variable and the second state variable are evaluated together.

Abstract: In a method for operating an electric machine a first test signal is fed into the electric machine and a first response signal of the electric machine is measured. A first state variable for a rotor of a synchronous reluctance motor of the electric machine is determined as a function of the first response signal, and a second state variable for the rotor of the synchronous reluctance motor is determined. The first state variable and the second state variable are evaluated together.

Abstract: A monitoring device for a reluctance machine includes a vector rotator for rotating a space phasor of the reluctance machine that depends on a voltage in a coordinate system that rotates with a negative fundamental frequency, a low-pass filter filtering the rotated space phasor and producing an output signal, and a signal evaluation device evaluating the output signal. A DC value of the produced output signal in the rotating coordinate system is monitored, and an error in operating the reluctance machine is identified when the DC value is above a predefined threshold value.

Abstract: A method for determining a rotor frequency and/or a rotor angle of a rotor of a reluctance machine, in particular without an amortisseur, is disclosed. The reluctance machine has a stator with a stator winding and the rotor has a magnetically anisotropic rotor core. The method includes applying a temporal sequence of voltage pulses to the stator winding, determining a sequential pulse response of a current flowing in the stator winding, the current being generated as a result of the voltage pulses and a flux being generated from the voltage pulses as a result of the magnetically anisotropic rotor core, and determining the rotor frequency and/or the rotor angle based on the measured sequential pulse response of the electric current by using an evaluating device.

Abstract: A method operates a multilevel converter for power factor correction of a polyphase mains voltage. Each phase of the polyphase main has an associated phase module with a plurality of sub modules which are connected in series and each have an electrical energy store. Each sub module can be connected to the phase of the mains voltage or disconnected there from by an electronic switch. A circuit breaker is provided for disconnecting the converter from the mains voltage. The converter has a regulation system by which the voltages of the phase modules are balanced when the circuit breaker is open.

Abstract: A method for determining a rotor frequency and/or a rotor angle of a rotor of a reluctance machine, in particular without an amortisseur, is disclosed. The reluctance machine has a stator with a stator winding and the rotor has a magnetically anisotropic rotor core. The method includes applying a temporal sequence of voltage pulses to the stator winding, determining a sequential pulse response of a current flowing in the stator winding, the current being generated as a result of the voltage pulses and a flux being generated from the voltage pulses as a result of the magnetically anisotropic rotor core, and determining the rotor frequency and/or the rotor angle based on the measured sequential pulse response of the electric current by using an evaluating device.

Abstract: A method operates a multilevel converter for power factor correction of a polyphase mains voltage. Each phase of the polyphase main has an associated phase module with a plurality of sub modules which are connected in series and each have an electrical energy store. Each sub module can be connected to the phase of the mains voltage or disconnected there from by an electronic switch. A circuit breaker is provided for disconnecting the converter from the mains voltage. The converter has a regulation system by which the voltages of the phase modules are balanced when the circuit breaker is open.

Abstract: In a method for field-oriented operation to zero speed of an encoder-less asynchronous machine, wherein the associated field-oriented regulation device has a monitor with a machine model and rotation-speed adaptation, a model flux and a model current are calculated from a calculated actuating voltage and an adapted rotation speed, from which, in conjunction with a determined machine current, a complex difference is calculated. Also calculated is a model slip rotation speed as a function of the model flux and the model current, which is then scaled. The adapted rotation speed is then superimposed, and the sum is used as the rotation speed actual value which supplied to a rotation-speed regulator. An asynchronous machine without an encoder can therefore be operated to zero speed on a field-oriented basis.

Abstract: In a method for field-oriented operation to zero speed of an encoder-less asynchronous machine, wherein the associated field-oriented regulation device has a monitor with a machine model and rotation-speed adaptation, a model flux and a model current are calculated from a calculated actuating voltage and an adapted rotation speed, from which, in conjunction with a determined machine current, a complex difference is calculated. Also calculated is a model slip rotation speed as a function of the model flux and the model current, which is then scaled. The adapted rotation speed is then superimposed, and the sum is used as the rotation speed actual value which supplied to a rotation-speed regulator. An asynchronous machine without an encoder can therefore be operated to zero speed on a field-oriented basis.

Abstract: A method and apparatus for connecting a converter to an asynchronous machine whose rotor is rotating with respect to the stator before and/or during the connection at some unknown rotation speed is disclosed. According to the present invention, a current is forced to flow, a rotor flux model vector and a stator current model vector are calculated as a function of a stator voltage and of an estimated rotation speed value. An error (e) is determined as a function of these calculated values and of a determined actual stator current vector, and the estimated rotation speed value is changed in such a manner that the determined error turns to zero. A method and apparatus are thus obtained for connecting a converter to an asynchronous machine, with the estimated rotation speed value converging in a very short time, starting from an initial value, to the actual mechanical rotation speed.