Fault compensating multi-step wave inverter

Claim 2

An multi-step, alternating current power supply having a failed-operation redundancy safety system comprising: a. an inverter for converting DC voltage to AC voltage, said inverter comprising: i. a multiple pair of inverter bridges, with each bridge having at least one pair of unidirectional conducting semiconductor switches, wherein an equal number of said switches are in circuit connection with a first DC power rail and the remaining equal number of said switches are in circuit connection with a second DC power rail; ii. triggering means to properly sequence the firing of each switch to-provide at least one output waveform from each inverter bridge, wherein each waveform is phase shifted; iii. a first transformer and a second transformer in circuit connection with each pair of inverter bridges, said first and second transformer each having a primary and a secondary winding, said primary windings being in circuit connection with the output of each associated pair of said inverting bridges, said primary winding of said first transformer being in wye-connection, and said primary winding of said second transformer being in delta-connection; and iv. said secondary windings being magnetically coupled with associated said primary windings, said secondary windings connected in a series-add connection, whereby a phase shift between each inverter bridge is such that said AC voltage waveform consists of at least 24 steps per cycle; wherein the compensation of said multi-step AC power supply during a fault condition comprises: b. sensing means to detect a short circuit within said semiconductor switches; c. identifying means to identify a short-circuited switch in a faulted inverter bridge; d. disabling means to disable the switches within said faulted inverter bridge complementary to said short-circuited switch; e. enabling means to enable the switches within said faulted inverter in circuit connection with the same DC power rail as said short-circuited switch; f. adjusting means to adjust the firing sequence of the remaining semiconductors not in circuit connection with said faulted inverter bridge wherein said phase shift between each active inverter bridge increases; whereby said AC voltage waveform consists of at least 18 steps per cycle.

Claim 3

An improved multi-step, alternating current power supply having a failed-operation redundancy safety system comprising: a. an electrical generator electrically connected to rectifying means for producing a DC voltage; b. regulating means to regulate said DC voltage at alternative voltage levels by controlling the output of said generator; and c. an inverter for converting said DC voltage to an AC voltage, said inverter comprising: i. a multiple pair of inverter bridges, with each bridge having at least one pair of unidirectional conducting semiconductor switches, wherein an equal number of said switches are in circuit connection with a first DC power rail and the remaining equal number of said switches are in circuit connection with a second DC power rail; ii. triggering means to properly sequence the firing of each switch to provide at least one output waveform from each inverter bridge, wherein each waveform is phase shifted; iii. a first transformer and a second transformer having primary windings in circuit connection with the output of each associated pair of said inverting bridges, said primary windings of said first transformer being in wye-connection, and said primary windings of said second transformer being in delta-connection; and iv. an individual secondary winding magnetically coupled with each of said primary windings, said secondary windings connected in a series-add connection, whereby a phase shift between each inverter bridge is such that said AC voltage waveform consists of at least 24 steps per cycle; wherein the improvement for compensating said multi-step AC power supply during a fault condition comprises: d. sensing means to detect a short circuit within said semiconductor switches; e. identifying means to identify a shortcircuited switch in a faulted inverter bridge; f. disabling means to disable the switches within said faulted inverter bridge complementary to said short-circuited switch; g. enabling means to enable the switches within said faulted inverter in circuit connection with the same DC power rail as said short-circuited switch; h. adjusting means to adjust the firing sequence of the remaining semiconductors not in circuit connection with said faulted inverter bridge wherein said phase shift between each active inverter bridge increases; whereby said AC voltage waveform consists of at least 18 steps per cycle.

Claim 4

An improved multi-step, alternating current power supply having a failed-operation redundancy safety system comprising: a. an electrical generator electrically connected to rectifying means for producing a DC voltage; b. regulating means to regulate said DC voltage at alternative voltage levels by controlling the output of said generator; and c. an inverter for converting said DC voltage to an AC voltage, said inverter comprising: i. a multiple pair of inverter bridges, with each bridge having at least one pair of unidirectional conducting semiconductor switches, wherein an equal number of said switches are in circuit connection with a first DC power rail and the remaining equal number of said switches are in circuit connection with a second DC power rail; ii. triggering means to properly sequence the firing of each switch to provide at least one output waveform from each inverter bridge, wherein each waveform is phase shifted; iii. a first transformer and a second transformer having primary windings in circuit connection with the output of each associated pair of said inverting bridges, said primary windings of said first transformer being in wye-connection, and said primary windings of said second transformer being in delta-connection; and iv. an individual secondary winding magnetically coupled with each of said primary windings, said secondary windings connected in a series-add connection, whereby a phase shift between each inverter bridge is such that said AC voltage waveform consists of at least 24 steps per cycle; wherein the improvement for compensating said multi-step AC power supply during a fault condition comprises: d. sensing means to detect a short circuit within said semiconductor switches; e. identifying means to identify a shortcircuited switch in a faulted inverter bridge; f. disabling means to disable the switches within said faulted inverter bridge complementary to said short-circuited switch; g. enabling means to enable the switches within said faulted inverter in circuit connection with the same DC power rail as said short-circuited switch; h. adjusting means to adjust the firing sequence of the remaining semiconductors not in circuit connection with said faulted inverter bridge wherein said phase shift between each active inverter bridge increases; whereby said AC voltage waveform consists of at least 18 steps per cycle.

Claim 5

The improved multi-step AC power supply of claim 2 wherein the sensing means is an optical coupler in circuit connection with each of said semiconductor switches.

Claim 6

The improved multi-step AC power supply of claim 2 wherein the identifying means, disabling means, enabling means and adjusting means are a function of an EPROM firing and logic control circuit.

Claim 7

The method of claim 2 wherein said inverter comprises 3 pair of inverter bridges and said AC voltage waveform comprises 36 steps per cycle.

Claim 8

The method of claim 5 wherein said phase shift between said inverter bridges increases from 10° to 12°.

Claim 9

The method of claim 2 wherein said inverter comprises 2 pair of inverter bridges and said AC voltage waveform comprises 24 steps per cycle.

Claim 10

The method of claim 7 wherein said phase shift between said inverter bridges increases from 15° to 20°.

Claim 13

The method of claim 9 wherein said inverter comprises 3 pair of inverter bridges.

Claim 14

The method of claim 10 wherein said phase shift between said inverter bridges increases from 10° to 12°.

Claim 15

The method of claim 9 wherein said inverter comprises 2 pair of inverter bridges.

Claim 16

The method of claim 12 wherein said phase shift between said inverter bridges increases from 15° to 20°.

Claim 17

The method of claim 9 further comprising regulating the field voltage of said generator wherein said DC voltage increases.