Abstract: A converter system, in particular for supplying electrical drives with direct current or DC voltage, or with alternating current or AC voltage, at a specifically matched frequency or for dynamic power factor correction. The converter system has at least one converter which has power semiconductors which can be switched on and/or off. It is possible to influence the current flow through the power semiconductors by adjusting the times at which the power semiconductors are switched on and off. It is also possible to influence the desired overall voltage or the desired overall current at the output of the converter by suitably controlling the times at which the individual power semiconductors of the converter are switched on and off.

Abstract: 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.

Abstract: 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.