Siemens Aktiengesellschaft

Walter Dreiseitl

Theodor Salzmann

Dieter Kollensperger

Wolf-Dieter Weigel

Thomas Schlegel

Felix Blaschke

Wilhelm Linden

Lothar Schleicher

Herbert Polster

Manfred Koch

Winfried Speth

Klaus Bohm

Karlheinz Bayer

A method and apparatus are disclosed for providing improved rotational speed determination for a rotating shaft. Two probes positioned adjacent a circular disk which rotates with the shaft scan markings on the disk and generate four out-of-phase signals in response to rotation of the shaft. A switch, controlled by logic circuitry which detects intersections of the signals, develops a composite saw-tooth-shaped signal from the four signals. A counter counts the number of crossings of the composite signal with a reference 'zero' value to develop a determination of the number of discrete angular positions traversed by the shaft during a specified time interval. A memory stores the value of the composite signal at the start of the time interval. Computation circuitry develops a rotational speed based on the counted number of positions, corrected by a factor derived from the difference between the stored value and the value of the composite signal at the end of the interval. Time control circuitry prevents the start or end of the time interval during switching and prevents switching during the start or end of the time interval.

Method and apparatus for determining rotational speed

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.

Rotating field machine drive and method

A circuit for forming an electrical quantity which is proportional to a flux component of a rotating field machine permitting an accurate measurement of the flux component during the starting up of the rotating field machine, the machine having for this purpose, two windings of which the first winding is suited for excitation and the second winding for taking off a voltage induced by the excitation, the circuit including an integrator preceded by an adder to which are fed as input variables the phase current, the time derivative of the same, the phase voltage of the rotating field machine, and the induced voltage, with a null regulator which can be switched on via an auxiliary switch after the excitation is switched on connected into the feedback path of the integrator, and a quantity proportional to the flux component taken off at the output of the integrator.

Circuit for forming an electrical quantity which is proportional to a

In controlled systems with dead time, particularly converter current controls, the reference value is fed directly to the final control element providing anticipatory control and, in addition is fed to the reference input of the controller through a dead time simulator. In accordance with a further feature, the difference between the input signal and the output signal of the dead time simulator can be added into the final control element as an additional control variable to compensate for inertia of the controlled system.

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Erlangen, Germany

Walter Dreiseitl