Siemens Aktiengesellschaft

Thomas Schlegel

Theodor Salzmann

Walter Dreiseitl

Wolf-Dieter Weigel

Dieter Kollensperger

For forming an electric voltage signal which is proportional to a flux component of a rotating-field machine, a voltage associated with the flux component is fed to the input of an integrator, and a voltage signal proportional to the flux component is taken off of the integrator. The input of a zero-controller for suppressing the DC component of this voltage signal is connected to the output of the integrator and the output of the zero-controller is connected to a summing point at the input of the integrator. This integrator circuit can be used to determine the position of the flux of a rotating field machine, with the correct phase and amplitude, and independently of frequency, while the zero-controller remains engaged at speeds from the beginning of localization of standing rotor position up to the nominal frequency of the machine. The zero-controller has a P-controller and an I-controller whose output signals are fed to the summing point. The output signal of the integrator, weighted in proportion to the frequency of the machine, is fed to the input of the P-controller and, weighted in proportion to the square of the frequency, is fed to the input of the I-controller, the weighting factor having a maximum value of one. The circuit constitutes an AC voltage integrator having a characteristic frequency which depends on the frequency of the rotating field machine, the intercept frequency and the attenuation remaining constant. The phase error remains constant over the entire speed range of the rotating field machine.

Circuit for generating an electric signal proportional to a flux

A drive for a rotating field machine which has two AC voltage integrators of identical design for forming two electric voltage signals each of which is proportional to a flux component in the machine. Each voltage integrator includes an integrator and a zero-controller having negative feedback for suppressing the DC component of input voltages fed to a summing point of the integrator. Each integrator, is fed, as one input voltage, a voltage proportional to the phase-voltage belonging to the flux component and a voltage proportional to the corresponding stator current in a machine supply lead, for compensating the ohmic stator voltage drop. A second voltage, also depending on the phase current, is processed to compensate for the inductive stator voltage drop. To ensure optimum converter and machine utilization over an increased speed control range by reducing the phase errors of the determined flux components, each zero-controller includes a proportional controller and an integrated controller having output signals fed to the summing point. The output signal of the integrator, corrected for the ohmic stator voltage drop and the inductive stray voltage, is fed, weighted proportionally to the frequency of the machine, to the input of the proportional controller, and weighted proportionally to the square of the frequency, to the input of the integrated controller, the weighting factor having a maximum value of 1.

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Hemhofen, Germany

Thomas Schlegel