Siemens Aktiengesellschaft

Wilhelm Linden

Walter Dreiseitl

Manfred Koch

Hartmut Schorrig

Horst Gehm

Werner Gratzke

Inverter system

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

In an inverter bridge having a recovery diode bridge associated therewith with the junction points in the inverter bridge coupled to corresponding junctions of the recovery diode bridge the d.c. inputs of the inverter are connected by means of symmetrically arranged electronic switches to the two d.c. supply voltage potentials with the recovery diode bridge connected to the d.c. supply ahead of the electronic switches. Also shown are auxiliary circuits including a capacitor, inductance and resistance associated with the electronic switches which permit elimination of the protective circuit components usually associated with the inverter semiconductors and recovery diodes.

Circuit arrangement for an inverter

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Erlangen, Germany

Wilhelm Linden