Control for direct-alternating current converter - compares actual and desired values of three varying signals

摘要

A device for producing a control signal comprises a source with at least three bipolar variable input signals. A valve setting device responds to a first set of two or more of the input signals which produces an output signal, from the first set, having the largest positive value. A second valve setter responds to this input signal and a second set of at least another of the input signals and derives a resultant error signal representing the largest negative value of the signals from a group of signals constituted by a selected signal of the second set and by the largest positive signal of the first set. A device connected to the second setting device produces a control signal responding to variations in the error signal.