Adaptive harmonic distortion control for parallel connected inverters

Claim 2

A control for a DC/AC converter system having first and second DC/AC converters that produce converter outputs and means for combining the converter outputs to produce an AC output waveform having a fundamental component and a harmonic component, comprising: means for isolating the harmonic component in the AC output waveform and detecting the magnitude thereof; and means responsive to the isolating means for developing first and second pulse-width modulated (PWM) control waveforms for controlling the first and second DC/AC converters, respectively, including means for phase delaying the second PWM control waveform relative to the first PWM control waveform to in turn regulate the magnitude of the harmonic component.

Claim 3

The control of claim 1, wherein the developing means further includes means for adjusting pulse widths of selected pulses in one of the PWM control waveforms in dependence upon the magnitude of the harmonic component.

Claim 4

The control of claim 1, wherein the developing means further includes means for adjusting pulse widths of selected pulses in both of the PWM control waveforms in dependence upon the magnitude of the harmonic component.

Claim 5

The control of claim 1, wherein the isolating means further includes means for sensing a magnitude of a DC component in one of the converter outputs and wherein the developing means is further responsive to the sensing means.

Claim 6

The control of claim 1, wherein the isolating means further includes means for sensing a magnitude of DC components in both of the converter outputs and wherein the developing means is further responsive to the sensing means.

Claim 7

The control of claim 1, wherein the developing means is further responsive to a magnitude of the fundamental components of the AC output waveform.

Claim 8

A DC/AC converter system, comprising: first and second DC/AC converters that produce converter outputs; an interphase transformer that combines the converter outputs to produce an AC output waveform having a fundamental component and harmonics thereof; and a digital signal processor having means for isolating harmonics in the AC output waveform and detecting the magnitudes thereof and means responsive to the detecting means for developing first and second pulse-width modulated (PWM) control waveforms for controlling the first and second DC/AC converters, respectively, wherein the second PWM control waveform is phase delayed relative to the first PWM control waveform by a phase delay dependent upon magnitudes of harmonics in the AC output waveform and wherein widths of pulses in the PWM control waveforms are controlled in dependence upon magnitudes of harmonics in the AC output waveform.

Claim 9

A DC/AC converter system, comprising: first and second DC/AC converters that produce converter outputs; an interphase transformer that combines the converter outputs to produce an AC output waveform having a fundamental component and harmonics thereof; and a digital signal processor having means for isolating harmonics in the AC output waveform and detecting the magnitudes thereof and means responsive to the detecting means for developing first and second pulse-width modulated (PWM) control waveforms for controlling the first and second DC/AC converters, respectively, wherein the second PWM control waveform is phase delayed relative to the first PWM control waveform by a phase delay dependent upon magnitudes of harmonics in the AC output waveform and wherein widths of pulses in the PWM control waveforms are controlled in dependence upon magnitudes of harmonics in the AC output waveform.

Claim 10

The DC/AC converter system of claim 7, wherein the widths of pulses in the PWM control waveforms are further controlled in accordance with a magnitude of the fundamental component of the AC output waveform.

Claim 11

The DC/AC converter system of claim 7, further including means for sensing magnitudes of DC components in the converter outputs and wherein the widths of pulses in the PWM control waveforms are further controlled in accordance with the magnitudes of the DC components.

Claim 12

A DC/AC converter system, comprising: first and second DC/AC converters each of which produces a plurality of phase outputs; an interphase transformer that combines corresponding phase outputs of the first and second DC/AC converters to produce a plurality of AC output waveforms wherein each output waveform includes a fundamental component and harmonics of the fundamental component; and a digital signal processor having means for isolating harmonics in the AC output waveforms and detecting the magnitudes of the harmonics and means responsive to the detecting means and the phase outputs of the DC/AC converters for developing first and second sets of pulse-width modulated (PWM) control waveforms for controlling the first and second DC/AC converters, respectively, wherein the second PWM control waveform is phase delayed relative to the first PWM control waveform by a phase delay dependent upon magnitudes of harmonics in the AC output waveforms and wherein widths of pulses in the PWM control waveforms are controlled in dependence upon magnitudes of harmonics in the AC output waveforms.

Claim 13

A DC/AC converter system, comprising: first and second DC/AC converters each of which produces a plurality of phase outputs; an interphase transformer that combines corresponding phase outputs of the first and second DC/AC converters to produce a plurality of AC output waveforms wherein each output waveform includes a fundamental component and harmonics of the fundamental component; and a digital signal processor having means for isolating harmonics in the AC output waveforms and detecting the magnitudes of the harmonics and means responsive to the detecting means and the phase outputs of the DC/AC converters for developing first and second sets of pulse-width modulated (PWM) control waveforms for controlling the first and second DC/AC converters, respectively, wherein the second PWM control waveform is phase delayed relative to the first PWM control waveform by a phase delay dependent upon magnitudes of harmonics in the AC output waveforms and wherein widths of pulses in the PWM control waveforms are controlled in dependence upon magnitudes of harmonics in the AC output waveforms.

Claim 14

The DC/AC converter system of claim 10, wherein the widths of pulses in the PWM control waveforms are further controlled in accordance with a magnitude of the fundamental component of each AC output waveform.

Claim 15

The DC/AC converter system of claim 11, further including means for sensing magnitudes of DC components in the converter outputs and wherein the widths of pulses in the PWM control waveforms are further controlled in accordance with the magnitudes of the DC components.