Utility current feedback filter with pulse-width modulated power converter

Claim 2

A power flow control apparatus coupled between an AC source of electrical energy and a DC source of electrical energy, said power flow control apparatus comprising: a power electronic converter coupled to the DC source and including a plurality of switches; a pulse-width modulation system coupled to the power electronic converter to control said plurality of switches to supply a power flow in accordance with a power flow control waveform responsive to a current reference signal; a passive filter coupled between said power electronic converter and said AC source; for individual phases of the AC source a current feedback sensor positioned at a feedback node between said passive filter and said AC source to supply a feedback signal, a feedback circuit coupled to receive said feedback signal, said feedback circuit processing said feedback signal to supply a processed feedback signal, and a summing circuit coupled to receive said processed feedback signal and the current reference signal, which is applied to said pulse-width modulation system, to produce a summed signal that controls said power electronic converter.

Claim 3

The apparatus of claim 1, wherein said pulse-width modulation system comprises: a gain circuit coupled to receive said summed signal; and a comparator circuit coupled to receive the output of the gain circuit, said comparator also having an input receiving a triangle wave, to produce a comparison output that is supplied to said power electronic converter.

Claim 4

The apparatus of claim 1 wherein said feedback circuit processes said feedback signal with a derivative gain (K d ), so that the feedback circuit processes the feedback signal in accordance with the relation K d S, where S comprises a Laplacian operator.

Claim 5

The apparatus of claim 1 wherein said feedback circuit further processes said feedback signal with a proportional gain (K f ), so that the feedback circuit processes the feedback signal in accordance with the relation K f +K d S, where S comprises a Laplacian operator and K d comprises a derivative gain multiplier.

Claim 6

The apparatus of claim 1, wherein said passive filter comprises, for each phase: a filter inductor coupled in series between said power electronic converter and said AC source.

Claim 7

The apparatus of claim 5 wherein said passive filter further comprises, for each phase: a filter resistor coupled in series with a filter capacitor between a node defined between said power electronic converter and said filter inductor, and a common node.

Claim 8

A power flow control apparatus comprising: a power electronic converter including a plurality of switches; a current reference generator that generates a current reference signal; a pulse-width modulation system responsive to said current reference signal for controlling said power electronic converter to supply an alternating current flow therethrough; a utility current feedback filter for controlling said power electronic converter to reduce the harmonic currents experienced during power conversion in said power electronic converter, said utility current feedback filter including a passive filter coupled between said power electronic converter and said AC source; for individual phases of the AC source a current feedback sensor positioned at a feedback node between said passive filter and said AC source to supply a feedback signal, a feedback circuit coupled to receive said feedback signal, said feedback circuit processing said feedback signal in accordance with the relation, K f +K d S, to supply a processed feedback signal, wherein (K f ) comprises a proportional gain, K d comprises a derivative gain, and S comprises a Laplacian operator, and a summing circuit coupled to receive said processed feedback signal and the current reference signal, to generate a summed signal which is applied to said pulse-width modulation system and said converter in order to control said converter.

Claim 9

A power flow control apparatus comprising: a power electronic converter including a plurality of switches; a current reference generator that generates a current reference signal; a pulse-width modulation system responsive to said current reference signal for controlling said power electronic converter to supply an alternating current flow therethrough; a utility current feedback filter for controlling said power electronic converter to reduce the harmonic currents experienced during power conversion in said power electronic converter, said utility current feedback filter including a passive filter coupled between said power electronic converter and said AC source; for individual phases of the AC source a current feedback sensor positioned at a feedback node between said passive filter and said AC source to supply a feedback signal, a feedback circuit coupled to receive said feedback signal, said feedback circuit processing said feedback signal in accordance with the relation, K f +K d S, to supply a processed feedback signal, wherein (K f ) comprises a proportional gain, K d comprises a derivative gain, and S comprises a Laplacian operator, and a summing circuit coupled to receive said processed feedback signal and the current reference signal, to generate a summed signal which is applied to said pulse-width modulation system and said converter in order to control said converter.

Claim 10

The apparatus of claim 7, wherein said pulse-width modulation system comprises: a gain circuit coupled to receive said summed signal; and a comparator circuit coupled to receive the output of the gain circuit, said comparator also having an input receiving a triangle wave, to produce a comparison output that is supplied to said power electronic converter.

Claim 11

The apparatus of claim 7, wherein said passive filter comprises, for each phase: a filter inductor coupled in series between said power electronic converter and said AC source.

Claim 12

The apparatus of claim 9 wherein said passive filter further comprises, for each phase: a filter resistor coupled in series with a filter capacitor between a node defined between said power electronic converter and said filter inductor, and a common node.

Claim 15

The method of claim 11, wherein said step b) includes processing said feedback signal with a derivative gain (K d ), so that said feedback processing circuit operates according to the relation K d S, where S comprises a Laplacian operator.

Claim 16

The method of claim 11, wherein said step b) processes said feedback signal with a proportional gain (K f ), so that said feedback processing circuit operates according to the relation K f .

Claim 17

The method of claim 11, wherein said step b) includes processing said feedback signal with a derivative gain (K d ) and a proportional gain (K f ), so that said feedback processing circuit operates according to the relation K f +K d S, wherein S comprises a Laplacian operator.

Claim 18

The method of claim 11, where said step c) includes the substeps of: ci) summing said processed feedback signal with a current reference signal in a summing circuit to produce a summed signal; and cii) applying said summed signal to a comparator which also receives an input of a triangle wave; ciii) comparing said summed signal to the triangle wave to produce a comparison output that is supplied to said power electronic converter.

Claim 21

A utility current feedback filter for use in a power flow control having an AC source of electrical energy and a DC source of electrical energy with a power converter coupled to the DC source, said filter comprising: a passive filter coupled between said power electronic converter and said AC source; for individual phases of the AC source a current feedback sensor positioned at a feedback node between said passive filter and said AC source to supply a feedback signal, a feedback circuit coupled to receive said feedback signal, said feedback circuit processing said feedback signal to supply a processed feedback signal, and a summing circuit coupled to receive said processed feedback signal and the current reference signal to produce a summed signal that controls said power electronic converter.

Claim 22

A utility current feedback filter for use in a power flow control having an AC source of electrical energy and a DC source of electrical energy with a power converter coupled to the DC source, said filter comprising: a passive filter coupled between said power electronic converter and said AC source; for individual phases of the AC source a current feedback sensor positioned at a feedback node between said passive filter and said AC source to supply a feedback signal, a feedback circuit coupled to receive said feedback signal, said feedback circuit processing said feedback signal to supply a processed feedback signal, and a summing circuit coupled to receive said processed feedback signal and the current reference signal to produce a summed signal that controls said power electronic converter.

Claim 23

The filter of claim 17 wherein said pulse-width modulation system comprises: a gain circuit coupled to receive said summed signal; and a comparator circuit coupled to receive the output of the gain circuit, said comparator also having an input receiving a triangle wave, to produce a comparison output that is supplied to said power electronic converter.

Claim 24

The filter of claim 17 wherein said feedback circuit processes said feedback signal with a derivative gain K d , so that the feedback circuit processes the feedback signal in accordance with the relation K d S, where S comprises a Laplacian operator.

Claim 25

The filter of claim 17 wherein said feedback circuit further processes said feedback signal with a proportional gain (K f ), so that the feedback circuit processes the feedback signal in accordance with the relation K f +K d S, where S comprises a Laplacian operator and K d comprises a derivative gain multiplier.

Claim 26

The filter of claim 17 wherein said passive filter comprises, for each phase: a filter inductor coupled in series between said power electronic converter and said AC source.

Claim 27

The filter of claim 21 wherein said passive filter further comprises, for each phase: a filter resistor coupled in series with a filter capacitor between a node defined between said power electronic converter and said filter inductor, and a common node.