US4357655A — Three-phase inverter

Claim 1

Independent Claim 233 words

A polyphase inverter, comprising: a direct current source of electrical energy; a plurality of switching means connected to said direct current source; gating means for selectively actuating said switching means for selected periods of time to produce a six-step output waveform having a predetermined fundamental frequency in each of a plurality of phases; means, operatively associated with said gating means, for varying said selected periods of time to control the percentage of selected harmonics in said six-step output waveforms; means for maintaining the amplitude of the fundamental frequency of said six-step output waveforms at a substantially constant volts/Hertz value; modulating means for varying said selected periods of time to produce notches in said six-step output waveforms, said notches being centered at predetermined locations in said six-step waveforms, said notches having predetermined width, and said polyphase inverter providing six-step output waveforms to a first phase, a second phase, and a third phase, said second phase having a phase angle of 120° relative to said first phase, said second phase having a phase angle of 240° relative to said first phase and wherein said notches in said first phase are symmetrically located about the 75°, 105°, 255°, and 285° points in the six-step output waveform thereof with the notches in the output waveforms of said second and third phases being out of phase with the notches in said first phase by 120° and 240°, respectively.

Claim 2

Dependent Claim 233 words

A polyphase inverter, comprising: a direct current source of electrical energy; a plurality of switching means connected to said direct current source; gating means for selectively actuating said switching means for selected periods of time to produce a six-step output waveform having a predetermined fundamental frequency in each of a plurality of phases; means, operatively associated with said gating means, for varying said selected periods of time to control the percentage of selected harmonics in said six-step output waveforms; means for maintaining the amplitude of the fundamental frequency of said six-step output waveforms at a substantially constant volts/Hertz value; modulating means for varying said selected periods of time to produce notches in said six-step output waveforms, said notches being centered at predetermined locations in said six-step waveforms, said notches having predetermined width, and said polyphase inverter providing six-step output waveforms to a first phase, a second phase, and a third phase, said second phase having a phase angle of 120° relative to said first phase, said second phase having a phase angle of 240° relative to said first phase and wherein said notches in said first phase are symmetrically located about the 75°, 105°, 255°, and 285° points in the six-step output waveform thereof with the notches in the output waveforms of said second and third phases being out of phase with the notches in said first phase by 120° and 240°, respectively.

Claim 3

Dependent Claim 21 words

A polyphase inverter according to claim 1 further including means for selectively varying the fundamental frequency of said six-step output waveforms.

Claim 4

Dependent Claim 93 words

A polyphase inverter according to claim 1 or 2 wherein said means for varying said selected periods of time includes: clock means for generating clock signals having a clock frequency which is a multiple of the fundamental frequency; interval timer means connected between said clock means and said gating means for providing a first signal indicative of a first selected time interval and a second signal indicative of a second selected time interval, said interval timer means including said means for maintaining the amplitude of the fundamental frequency of said six-step output waveforms.

Claim 5

Dependent Claim 37 words

A polyphase inverter according to claim 3 wherein said means for maintaining the amplitude of the fundamental frequency of said six-step output waveform includes means for controlling the duration of signals output by said interval timer means.

Claim 6

Dependent Claim 21 words

A polyphase inverter according to claim 4 wherein said selected harmonics include the fifth and seventh harmonics of said fundamental frequency.

Claim 7

Dependent Claim 212 words

A polyphase inverter for providing six-step output waveforms to a first phase, a second phase, and a third phase, said second phase having a phase angle of 120° relative to first phase, said third phase having a phase angle of 240° relative to said first phase, comprising: a direct current source of electrical energy; a plurality of switch means connected to said direct current source; gating means for selectively actuating said switching means for selected periods of time to produce six-step output waveforms having a predetermined fundamental frequency in each of said phases; clock means for generating clock signals having a clock frequency which is a multiple of the fundamental frequency; and interval timer means connected between said clock means and said gating means for generating timing signals for controlling said selective periods of time to produce a plurality of notches in said six-step output waveforms to modulate said six-step output waveforms to provide a constant volts/Hertz value and to control the percentages of selected harmonics therein, said first phase having notches symmetrically located about the 75°, 105°, 255°, and 285° points therein with the notches in the output waveforms of said second and third phases being out of phase with the notches in said first phase by 120° and 240°, respectively.

Claim 8

Dependent Claim 212 words

A polyphase inverter for providing six-step output waveforms to a first phase, a second phase, and a third phase, said second phase having a phase angle of 120° relative to first phase, said third phase having a phase angle of 240° relative to said first phase, comprising: a direct current source of electrical energy; a plurality of switch means connected to said direct current source; gating means for selectively actuating said switching means for selected periods of time to produce six-step output waveforms having a predetermined fundamental frequency in each of said phases; clock means for generating clock signals having a clock frequency which is a multiple of the fundamental frequency; and interval timer means connected between said clock means and said gating means for generating timing signals for controlling said selective periods of time to produce a plurality of notches in said six-step output waveforms to modulate said six-step output waveforms to provide a constant volts/Hertz value and to control the percentages of selected harmonics therein, said first phase having notches symmetrically located about the 75°, 105°, 255°, and 285° points therein with the notches in the output waveforms of said second and third phases being out of phase with the notches in said first phase by 120° and 240°, respectively.

Claim 9

Independent Claim 112 words

A method for converting direct current into polyphase alternating current, comprising the steps of: connecting a plurality of switching means to a direct current source of electrical energy; selectively actuating said switching means for selected periods of time with a gating means output to produce output waveforms having a fundamental frequency in each of a plurality of phases; varying said selected periods of time to control the percentage of selected harmonics in said output waveform in each phase; and maintaining the amplitude of the fundamental frequency in the output waveform at a substantially constant volts/Hertz value in each phase by varying the width of pulses generated upon actuation of said switching means.

Claim 10

Independent Claim 112 words

A method for converting direct current into polyphase alternating current, comprising the steps of: connecting a plurality of switching means to a direct current source of electrical energy; selectively actuating said switching means for selected periods of time with a gating means output to produce output waveforms having a fundamental frequency in each of a plurality of phases; varying said selected periods of time to control the percentage of selected harmonics in said output waveform in each phase; and maintaining the amplitude of the fundamental frequency in the output waveform at a substantially constant volts/Hertz value in each phase by varying the width of pulses generated upon actuation of said switching means.

Claim 11

Dependent Claim 13 words

A method according to claim 7 wherein said output waveforms are six-step waveforms.

Claim 12

Dependent Claim 23 words

A method according to claim 8 further including the step of selectively varying the fundamental frequency of said output waveform in each phase.

Claim 13

Dependent Claim 114 words

A method according to claim 7 or 9 further including the steps of: generating clock signals having a clock frequency which is a multiple of the fundamental frequency; counting said clock signals; actuating a first interval timing means with the rising edges of said clock signals to generate a first timing signal indicative of a first selected time interval; actuating a second interval timing means with the falling edges of said signal to generate a second timing signal indicative of a second selected time interval; and controlling the output of said gating means with the outputs of said ring counter and said first and second interval timing means for selectively actuating said switching means.

Claim 14

Dependent Claim 25 words

A method according to claim 10 wherein said maintaining step includes controlling the duration of signals output by said first and second interval timer means.

Claim 15

Dependent Claim 20 words

A method according to claim 11 wherein said selected harmonics are the fifth and seventh harmonics in said output waveform.

Claim 16

Independent Claim 152 words

A method for converting direct current into three-phase alternating current, comprising the steps of: generating six-step waveforms having a predetermined fundamental frequency in a first phase, a second phase and a third phase, the waveform of said second phase having a phase angle of 120° relative to the waveform of said first phase, the waveform of said third phase having a phase angle of 240° relative to the waveform of said first phase; modulating the six-step waveforms to produce notches therein, the notches in the first phase being symmetrically located about the 75°, 105°, 255° and 285° in the output waveform thereof, the notches in the second and third phases having phase angles of 120° and 240°, respectively, with the notches in the first phase; and controlling the notch angles to vary the fundamental frequency while maintaining a substantially constant ratio of voltage to fundamental frequency in the output of each phase.

Claim 17

Independent Claim 152 words

A method for converting direct current into three-phase alternating current, comprising the steps of: generating six-step waveforms having a predetermined fundamental frequency in a first phase, a second phase and a third phase, the waveform of said second phase having a phase angle of 120° relative to the waveform of said first phase, the waveform of said third phase having a phase angle of 240° relative to the waveform of said first phase; modulating the six-step waveforms to produce notches therein, the notches in the first phase being symmetrically located about the 75°, 105°, 255° and 285° in the output waveform thereof, the notches in the second and third phases having phase angles of 120° and 240°, respectively, with the notches in the first phase; and controlling the notch angles to vary the fundamental frequency while maintaining a substantially constant ratio of voltage to fundamental frequency in the output of each phase.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1985-11-01	1986-05-03	1986-11-02	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1989-11-01	1990-05-03	1990-11-02	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1993-11-01	1994-05-03	1994-11-02	$7700.00	Window Closed / Lapsed

Three-phase inverter

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