Abstract: The invention relates to A method for determining a rotational velocity of a transducerless polyphase machine that is operated in a field-oriented manner, a stator-current model space vector and a conjugate complex reference space vector being calculated using a complete machine model, and the torques-active and dummy variables being measured from these model space vectors and from the measured stator-current actual space vector, from which active and dummy variables, in each case, a system deviation is determined. These measured system deviations are weighted and finally totaled, this total system deviation being used for adjusting the model rotor angular velocity such that the total system deviation becomes zero. Thus a method for determining the rotational velocity of a transducerless polyphase machine that is operated in a field-oriented manner is possible, breakdown protection being assured.

Abstract: A method and a device are described for determining an angular velocity of the rotor of a polyphase machine operated by field orientation without a transmitter, wherein control signals, a stator current model space vector and a conjugated complex reference space vector are calculated by a signal processor containing, among other things, a complete machine model and a modulator, as a function of a flux setpoint, a torque setpoint, a d.c. voltage value, measured power converter output voltage values and system parameters, with a real stator current space vector which is measured and the calculated stator current model space vector are being multiplied by the calculated conjugated complex reference space vector, and the imaginary components of the results being compared with one another, and the system deviation determined therefrom being used to adjust the angular velocity of the rotor as a system parameter in such a way that the system deviation thus determined becomes zero.

Abstract: A method for controlling the torque of a squirrel-cage rotor asynchronous machine supplied by an inverter driven by pulse-width modulation, includes converting a desired torque value (M.sub.des) and an actual torque value (M) in accordance with ##EQU1## into a corresponding desired value (x.sub.rdes) of a rotor angular frequency and a rotor angular frequency (.omega..sub.r). The torque is controlled through a rotor frequency controller and a controller of an absolute value of a total flux in accordance with ##EQU2## In these equations: R.sub.r =rotor resistance;.sub.r =rotor flux space vector;e.sub.sy =stator frequency factor;e.sub.sx =flux correction factor;V.sub.M, v.psi.=P gains of the controllers;.tau..sub.M, .tau..sub.W =reset times of the controllers;W.sub.des =desired value of total flux; and.sub..mu. =total flux space vector.

Abstract: A method for controlling a rotating-field machine supplied from an inverter, the output voltage system of the inverter being variable with respect to amplitude, phase and frequency includes supplying amplitudes of stator flux components formed from measured stator current components and stator voltage components as actual value of a flux control loop, and changing the phase and frequency of the inverter output voltage system with a flux control as a function of a predetermined stator flux reference value by directly setting-in the switching state of the inverter and an apparatus for carrying out the method.

Abstract: Circuit for controlling reactive currents of a three-phase network, having three converters with forced commutation connected in parallel with the loads of the three-phase network, at least one energy accumulator connected to the d-c side of the converter, and a closed control loop having measuring transformers for input currents of the converter, for the load currents and for the conductor voltages of the network, means for evaluating required compensation currents and means for controlling firing pulse formers for the converters to adjust the waveform of the currents on the three-phase side, including capacitors shunted across the loads in three phases, the compensation control element being a three-phase four-quadrant control element, the energy accumulator being an additional capacitor and a resonant circuit tuned to twice the network frequency, the resonant circuit being connected in parallel to the additional capacitor, the control loop including means for controlling the mean voltage on the d-c side of