Multiple bridge differential voltage static inverter

Claim 2

In an electrical inverter apparatus operative with a direct current potential source for supplying alternating current potential to a load, the combination of, a plurality of inverter power stages, each including a plurality of conduction controlled switching devices for controllAbly completing a circuit to said load, an interphase transformer operatively coupled to the output of each of said power stages, each of said interphase transformers having taps positioned to provide a plurality of predetermined unequal output voltage values corresponding to prescribed percentages of said direct current potential, and circuit means for controlling conduction of said switching devices to arithmetically combine in a sequential manner various of said voltage values of said interphase transformers to produce a pattern of voltage pulses of various magnitudes forming a predetermined voltage waveform at said load.

Claim 3

In an electrical inverter apparatus as claimed in claim 1 wherein said plurality of power stages comprises a first and second inverter bridge circuit means.

Claim 4

In an electrical inverter apparatus as claimed in claim 2 wherein said first inverter bridge circuit means comprises a full bridge circuit with said conduction controlled switching devices positioned in the legs thereof, and including an interphase output transformer having a movable tap for dividing the winding of said interphase output transformer into two sections, said movable tap being operatively connected to said first terminal of said load, said movable tap being positioned to establish a predetermined voltage magnitude across each of said sections.

Claim 5

In an electrical inverter apparatus as claimed in claim 3 wherein said second inverter bridge circuit comprises a full bridge with said conduction controlled switching devices positioned in the legs thereof, and including an interphase output transformer having a movable tap for dividing the winding of said interphase output transformer into two sections, said movable tap being operatively connected to said second terminal of said load, said movable tap being positioned to establish a predetermined voltage magnitude across each of said sections.

Claim 6

In an electrical inverter apparatus as claimed in claim 4 wherein the magnitude of the voltages established across each of said interphase output transformers equals the magnitude of the voltage supplied by said direct current potential source.

Claim 7

In an electrical inverter apparatus as claimed in claim 1 wherein said pattern of voltage pulses approximates a sinewave having both positive and negative half cycles and exhibiting little harmonic content.

Claim 8

In an electrical inverter apparatus as claimed in claim 6 including a filter means operatively connected between the outputs of said first and second inverter bridge circuit means and said load.

Claim 9

In an inverter apparatus operative with a source of direct current potential for supplying polyphase alternating current potential to a polyphase load, the combination of, multiple full bridge inverter circuit means, each including conduction control switching devices in the legs thereof, the number of full bridge inverter circuit means corresponding to the number of output phases of said inverter apparatus, each full bridge inverter circuit means including an interphase output transformer having a movable tap for dividing the winding of said interphase output transformer into two sections, said movable tap being positioned to establish a different predetermined voltage magnitude across each of said sections, said movable taps of said interphase output transformers being operatively connected to said polyphase load, and circuit means for controlling the conduction of the conduction control switching devices of the respective full bridge inverter circuits to arithmetically combine in a sequential manner various of said predetermined voltage magnitudes to produce a pattern of voltage pulses of various magnitudes to form a predetermined voltage waveform at said load.

Claim 10

In an inverter apparatus operative with a source of direct current potential for supplying polyphase alternating current potential to a polyphase load, the combination of, multiple full bridge inverter circuit means, each including conduction control switching devices in the legs thereof, the number of full bridge inverter circuit means corresponding to the number of output phases of said inverter apparatus, each full bridge inverter circuit means including an interphase output transformer having a movable tap for dividing the winding of said interphase output transformer into two sections, said movable tap being positioned to establish a different predetermined voltage magnitude across each of said sections, said movable taps of said interphase output transformers being operatively connected to said polyphase load, and circuit means for controlling the conduction of the conduction control switching devices of the respective full bridge inverter circuits to arithmetically combine in a sequential manner various of said predetermined voltage magnitudes to produce a pattern of voltage pulses of various magnitudes to form a predetermined voltage waveform at said load.

Claim 11

In an inverter apparatus as claimed in claim 7 wherein the positioning of the movable taps of the respective interphase output transformers is identical.

Claim 12

In an electrical inverter apparatus as claimed in claim 3 wherein the magnitude of the predetermined voltage developed across each of the sections of said interphase output transformers is different.

Claim 13

In an electrical inverter apparatus as claimed in claim 10 wherein the magnitudes of said predetermined voltages correspond to 15 percent of the direct current potential, 35 percent of the direct current potential, 65 percent of the direct current potential and 85 percent of the direct current potential, respectively.