Patent ID: 7751211

Claim:
An instantaneous voltage-drop compensation circuit comprising: a first voltage detector which detects three-phase voltages to be input to a power converter and outputs three-phase voltage signals, the converter converting three-phase alternating current to direct current, based on control pulse signals; a first three-phase to two-phase converter which converts the detected three-phase voltage signals to two-phase voltage signals; a first current detector which detects three-phase currents to be input to the power converter and outputs three-phase current signals; a second three-phase to two-phase converter which converts the detected three-phase current signals to two-phase current signals; a first subtracter which generates a first deviation signal from input current command signals and the two-phase current signals; an input current controller which generates input current control signals based on the first deviation signal; a first adder which adds the two-phase voltage signals to the input current control signals; a first two-phase to three-phase converter which converts input current control signals, to which the two-phase voltage signals have been added, to three-phase control signals; a control pulse signal generator which generates the control pulse signals for the power converter based on the three-phase control signals and outputs the control pulse signals to the power converter; a positive-phase negative-phase separator which separates the converted two-phase voltage signals into positive-phase components and negative-phase components; a second two-phase to three-phase converter which converts the separated negative-phase components of the two-phase voltage signals to negative-phase components of the three-phase voltage signals; a zero-phase voltage extractor which extracts a zero-phase voltage signal from the detected three-phase voltage signals; and a second adder which adds the negative-phase components of the three-phase voltage signals and the zero-phase voltage signal to the three-phase control signals, wherein the first adder adds the separated positive-phase components of the two-phase voltage signals to the input current control signals, and the control pulse signal generator generates the control pulse signals based on three-phase control signals resulted from the sum of the negative-phase components of the three-phase voltage signals and the zero-phase voltage signal.