Poly-phase ac/dc active power converter
AssigneeAmetek, Inc.
InventorWilliam J. Kazlauskas
Life of this patent
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Abstract
A three-phase AC/DC active power converter provides an H-bridge that is controlled by a DSP (digital signal processing) controller that places the H-bridge in a voltage-boost mode of operation when voltage of a DC-link capacitor maintained by the H-bridge is near than the voltage input from a three-phase power source. The voltage difference between the boosted DC-link voltage and the three-phase power source voltage provides a voltage potential thereby giving the control loops a possible gain value. The gain value provides loop stability to thereby prevent an inrush of electrical current into the power converter upon startup. The converter also allows harmonic distortion to be modified through wave shaping of the normally pure sinus conduction signal.
Claims20
A poly-phase AC/DC active power converter to convert AC power from a poly-phase variable frequency power source into DC power, comprising:
- an H-bridge converter maintaining a capacitor at its output, said converter adapted to receive each of the phases of AC power source at its input through respective line reactors inline therewith;
- and
- a controller coupled to said H-bridge converter to control said converter in accordance with a control structure, wherein upon the initial powering of said H-bridge, said controller enters a voltage boost mode, such that said line reactors are charged and discharged into said capacitor to raise its voltage above that of said power source, to generate a gain value used by said control structure to control the current consumed from the power source, so as to maintain a constant output voltage during the start up of a normal AC/DC conversion mode, so as to reduce an inrush of current during the conversion of AC power into DC power.
A method of controlling an H-bridge to convert AC power from a poly-phase power source into DC power comprising:
- providing an H-bridge power converter maintaining a DC-link capacitor at its output;
- providing a controller to control said H-bridge in accordance with a control structure;
- coupling the input of said H-bridge to the power source;
- operating said H-bridge in a boost mode, so as to charge said DC-link capacitor to a voltage above the voltage of the power source to generate a gain value;
- executing said control structure with said gain value to control the current consumed by said converter to maintain a constant output voltage;
- and
- operating said H-bridge in a normal mode, so as to convert AC power from the power source into DC power.
A method of controlling an AC/DC power converter to convert AC power from a 3-phase power source into DC power comprising:
- providing an H-bridge having a DC output bus, which maintains a DC-link capacitor;
- providing a controller to control said H-bridge in accordance with a control structure;
- representing at least 2 of the 3 phase voltages output from the power source as vectors in two-phase rotary coordinates;
- calculating a conduction angle of the power consumed from the 3-phase power source from said vectors using an arc-tangent function;
- and
- controlling said H-bridge to adjust the phase angle of the current consumed from the power source to match the phase angle of the voltage provided by the power source at said DC output bus, to provide unity power factor.
Dependencies are inferred from the claim text.