Three-phase converter for polyphase induction motors

Claim 2

A three-phase converter for an induction motor having a first, second and third phase, comprising: a) an input transformer having a primary winding and a first and second secondary winding associated with said primary winding, wherein said first and second secondary windings have a plurality of phases; b) a first bidirectional group of power semiconductors being coupled to the plurality of phases of said first secondary winding; c) a second bidirectional group of power semiconductors being coupled to the plurality of phases of said second secondary winding; d) a third bidirectional group of power semiconductors being coupled to the plurality of phases of said first secondary winding; e) a fourth bidirectional group of power semiconductors being coupled to the plurality of phase of said second secondary winding; f) a fifth bidirectional group of power semiconductors being coupled to the plurality of phases of said first secondary winding; and g) a sixth bidirectional group of power semiconductors being coupled to the plurality of phases of said second secondary winding, wherein the first phase of the induction motor is coupled in series between said first and fourth bidirectional groups of power semiconductors, the second phase of the induction motor is coupled in series between said third and sixth bidirectional groups of power semiconductors and the third phase of the induction motor is coupled in series between said fifth and second bidirectional groups of power semiconductors, whereby the first, second and third phases of the induction motor are not connected to each other but rather form a virtual star point.

Claim 3

The three-phase conveter according to claim 1, further comprising a controller controlling the first through sixth bidirectional groups of power semiconductors, whereby said controller activates the power semiconductors in sequence with overlapping ignition pulses.

Claim 4

The three-phase converter according to claim 2, wherein the overlapping ignition pulses are achieved by maintaining the power semiconductors ready to engage and activating them before a calculated current zero crossing.

Claim 5

The three-phase converter according to claim 1, wherein the first and second secondary windings are nested into a single coil.

Claim 6

The three-phase converter according to claim 2, wherein the first and second secondary windings are nested into a single coil.

Claim 7

The three-phase converter according to claim 3, wherein the first and second windings are nested into a single coil.

Claim 8

The three-phase converter according to claim 1, further comprising: h) a first balance coil being coupled to said first bidirectional group of power semiconductors; i) a second balance coil being coupled to said second bidirectional group of a power semiconductors; j) a third balance coil being coupled to said third bidirectional group of power semiconductors; k) a fourth balance coil being coupled to said fourth bidirectional group of power semiconductors, wherein the first motor phase is coupled in series between the first and fourth balance coils; l) a fifth balance coil being coupled to said fifth bidirectional group of power semiconductors, wherein the second motor phase is coupled in series between the second and fifth balance coils; and m) a sixth balance coil being coupled to said sixth bidirectional group of power semiconductors, wherein the third motor phase is coupled in series between the third and sixth balance coils.

Claim 9

The three-phase converter according to claim 2, further comprising: h) a first balance coil being coupled to said first bidirectional group of power semiconductors; i) a second balance coil being coupled to said second bidirectional group of power semiconductors; j) a third balance coil being coupled to said third bidirectional group of power semiconductors; k) a fourth balance coil being coupled to said fourth bidirectional group of power semiconductors, wherein the first motor phase is coupled in series between the first and fourth balance coils; l) a fifth balance coil being coupled to said fifth bidirectional group of power semiconductors, wherein the second motor phase is coupled in series between the second and fifth balance coils; and m) a sixth balance coil being coupled to said sixth bidirectional group of power semiconductors, wherein the third motor phase is coupled in series between the third and sixth balance coils.

Claim 10

The three-phase converter according to claim 3, further comprising: h) a first balance coil being coupled to said first bidirectional group of power semiconductors; i) a second balance coil being coupled to said second bidirectional group of power semiconductors; j) a third balance coil being coupled to said third bidirectional group of power semiconductors; k) a fourth balance coil being coupled to said fourth bidirectional group of power semiconductors, wherein the first motor phase is coupled in series between the first and fourth balance coils; l) a fifth balance coil being coupled to said fifth bidirectional group of power semiconductors, wherein the second motor phase is coupled in series between the second and fifth balance coils; and m) a sixth balance coil being coupled to said sixth bidirectional group of power semiconductors, wherein the third motor phase is coupled in series between the third and sixth balance coils.

Claim 11

The three-phase converter according to claim 4, further comprising: h) a first balance coil being coupled to said firs bidirectional group of power semiconductors; i) a second balance coil being coupled to said second bidirectional group of power semiconductors; j) a third balance coil being coupled to said third bidirectional group of power semiconductors; k) a fourth balance coil being coupled to said fourth bidirectional group of power semiconductors, wherein the first motor phase is coupled in series between the first and fourth balance coils; l) a fifth balance coil being coupled to said fifth bidirectional group of power semiconductors, wherein the second motor phase is coupled in series between the second and fifth balance coils; and m) a sixth balance coil being coupled to said sixth bidirectional group of power semiconductors, wherein the third motor phase is coupled in series between the third and sixth balance coils.

Claim 12

The three-phase converter according to claim 7, wherein the first through sixth balance coils have two branches.

Claim 13

The three-phase converter according to claim 8, wherein the first through sixth balance coils have three branches.

Claim 14

The three-phase converter according to claim 8, wherein the first through sixth balance coils have three branches.

Claim 15

A three-phase conveter for an induction motor having a first, second and third phase, comprising: a) an input transformer having a primary winding and a first, second, third and fourth secondary winding associated with said primary winding, wherein said first, second, third and fourth secondary windings each have a plurality of phases; b) a first, second and third bidirectional group of power semiconductors being coupled to the plurality of phases of said first secondary winding; c) a fourth, fifth and sixth bidirectional group of power semiconductors being coupled to the plurality of phases of said second secondary winding; d) a seventh, eight and ninth bidirectional group of power semiconductors being coupled to the plurality of phases of said third secondary winding; e) a tenth, eleventh and twelfth bidirectional group of power semiconductors being coupled to the plurality of phases of said fourth secondary winding; f) a first balance coupled being coupled in series between said first and fourth bidirectional groups of power semiconductors and having a center tap; g) a second balance coil being coupled in series between said second and fifth bidirectional group of power semiconductors and having a center tap; h) a third balance coil being coupled in series between said third and sixth bidirectional groups of power semiconductors and having a center tap; i) a fourth balance coil being coupled in series between said seventh and tenth bidirectional group of power semiconductors and having a center tap, wherein the first phase of the induction motor is coupled in series between the center taps of said first and fourth balance coils; j) a fifth balance coil being coupled in series between said eights and eleventh bidirectional groups of power semiconductors and having a center tap, wherein the second phase of the induction motor is coupled in series between the center taps of said second and fifth balance coils; and k) a sixth balance coil being coupled in series between said ninth and twelfth bidirectional groups of power semiconductors and having a center tap, wherein the third phase of the induction motor is coupled in series between the center taps of said third and sixth balance coils; whereby the first, second and third phases of the induction motor are not connected but rather form a virtual star point.

Claim 16

A three-phase conveter for an induction motor having a first, second and third phase, comprising: a) an input transformer having a primary winding and a first, second, third and fourth secondary winding associated with said primary winding, wherein said first, second, third and fourth secondary windings each have a plurality of phases; b) a first, second and third bidirectional group of power semiconductors being coupled to the plurality of phases of said first secondary winding; c) a fourth, fifth and sixth bidirectional group of power semiconductors being coupled to the plurality of phases of said second secondary winding; d) a seventh, eight and ninth bidirectional group of power semiconductors being coupled to the plurality of phases of said third secondary winding; e) a tenth, eleventh and twelfth bidirectional group of power semiconductors being coupled to the plurality of phases of said fourth secondary winding; f) a first balance coupled being coupled in series between said first and fourth bidirectional groups of power semiconductors and having a center tap; g) a second balance coil being coupled in series between said second and fifth bidirectional group of power semiconductors and having a center tap; h) a third balance coil being coupled in series between said third and sixth bidirectional groups of power semiconductors and having a center tap; i) a fourth balance coil being coupled in series between said seventh and tenth bidirectional group of power semiconductors and having a center tap, wherein the first phase of the induction motor is coupled in series between the center taps of said first and fourth balance coils; j) a fifth balance coil being coupled in series between said eights and eleventh bidirectional groups of power semiconductors and having a center tap, wherein the second phase of the induction motor is coupled in series between the center taps of said second and fifth balance coils; and k) a sixth balance coil being coupled in series between said ninth and twelfth bidirectional groups of power semiconductors and having a center tap, wherein the third phase of the induction motor is coupled in series between the center taps of said third and sixth balance coils; whereby the first, second and third phases of the induction motor are not connected but rather form a virtual star point.

Claim 17

The three-phase converter according to claim 14, further comprising a controller controlling the first through twelfth bidirectional groups of power semiconductors, whereby said controller activates the power semiconductors in sequence with overlapping ignition pulses.

Claim 18

The three-phase converter according to claim 15, wherein the overlapping ignition pulses are achieved by maintaining the power semiconductors ready to engage and activating them before a calculated current zero crossing.

Claim 19

The three-phase converter according to claim 14, wherein the first through fourth secondary windings are nested into a single coil.

Claim 20

The three-phase converter according to claim 15, wherein the first through fourth secondary windings are nested into a single coil.

Claim 21

The three-phase conveter according to claim 16, wherein the first through fourth secondary windings are nested into a single coil.

Claim 22

A three-phase converter for an induction motor having a first, second and third phase, comprising: a) an input transformer having a primary windings and a first, second, third, fourth, fifth and sixth secondary winding associated with said said primary winding, wherein said first through sixth secondary windings each have a plurality of phases; b) a first, second and third bidirectional group of power semiconductors being coupled to the plurality of phases of said first secondary winding; c) a fourth, fifth and sixth bidirectional group of power semiconductors being coupled to the plurality of phase of said second secondary winding; d) a seventh, either and ninth bidirectional group of power semiconductors being coupled to the plurality of phases of said third secondary winding; e) a tenth, eleventh and twelfth bidirectional group of power semiconductors being coupled to the plurality of phases of said fourth secondary winding; f) a thirteenth, fourteenth and fifteenth bidirectional group of power semiconductors being coupled to the plurality of of phases of said firth secondary winding; g) a sixteenth, seventeenth and eighteenth bidirectional group of power semiconductors being coupled to the plurality of phases of said sixth secondary winding; h) a first balance coil having a center tap, a first branch coupled to said first bidirectional group of power semiconductors, a second branch coupled to said fourth bidirectional group of power semiconductors and a third branch coupled to said seventh bidirectional group of power semiconductors; i) a second balance coil having a center tap, a first branch coupled to said second bidirectional group of power semiconductors, a second branch coupled to said fifth bidirectional group of power semiconductors and a third branch coupled to said eight bidirectional group of power semiconductors; j) a third balance coil having a center tap, a first branch coupled to said third bidirectional group of power semiconductors, a second branch coupled to said sixth bidirectional group of power semiconductors and a third branch coupled to said ninth bidirectional group of power semiconductors; k) a fourth balance coil having a center tap, a first branch coupled to said tenth bidirectional group of power semiconductors, a second branch coupled to said thirteenth bidirectional group of power semiconductors and a third branch coupled to said sixteenth bidirectional group of power semiconductors, wherein the first phase of the induction motor is coupled in series between the center taps of said first and fourth balance coils; l) a fifth balance coil having a center tap, a firs branch coupled to said eleventh bidirectional group of power semiconductors, a second branch coupled to said fourteenth bidirectional group of power semiconductors and a third branch coupled to said seventeenth bidirectional group of power semiconductors, wherein the second phase of the induction motor is coupled in series between the center tap of said second and fifth balance coils; and m) a sixth balance coil having a center tap, a first branch coupled to said twelfth bidirectional group of power semiconductors, sa second branch coupled to said fifteenth bidirectional group- of power semiconductors and a third branch coupled to said eighteenth bidirectional group of power semiconductors, wherein the third phase of the induction motor is coupled in series between said third and sixth balance coils, and the first, second and third phase of the induction motor are not a connected to each other but rather form a virtual star point.

Claim 23

A three-phase converter for an induction motor having a first, second and third phase, comprising: a) an input transformer having a primary windings and a first, second, third, fourth, fifth and sixth secondary winding associated with said said primary winding, wherein said first through sixth secondary windings each have a plurality of phases; b) a first, second and third bidirectional group of power semiconductors being coupled to the plurality of phases of said first secondary winding; c) a fourth, fifth and sixth bidirectional group of power semiconductors being coupled to the plurality of phase of said second secondary winding; d) a seventh, either and ninth bidirectional group of power semiconductors being coupled to the plurality of phases of said third secondary winding; e) a tenth, eleventh and twelfth bidirectional group of power semiconductors being coupled to the plurality of phases of said fourth secondary winding; f) a thirteenth, fourteenth and fifteenth bidirectional group of power semiconductors being coupled to the plurality of of phases of said firth secondary winding; g) a sixteenth, seventeenth and eighteenth bidirectional group of power semiconductors being coupled to the plurality of phases of said sixth secondary winding; h) a first balance coil having a center tap, a first branch coupled to said first bidirectional group of power semiconductors, a second branch coupled to said fourth bidirectional group of power semiconductors and a third branch coupled to said seventh bidirectional group of power semiconductors; i) a second balance coil having a center tap, a first branch coupled to said second bidirectional group of power semiconductors, a second branch coupled to said fifth bidirectional group of power semiconductors and a third branch coupled to said eight bidirectional group of power semiconductors; j) a third balance coil having a center tap, a first branch coupled to said third bidirectional group of power semiconductors, a second branch coupled to said sixth bidirectional group of power semiconductors and a third branch coupled to said ninth bidirectional group of power semiconductors; k) a fourth balance coil having a center tap, a first branch coupled to said tenth bidirectional group of power semiconductors, a second branch coupled to said thirteenth bidirectional group of power semiconductors and a third branch coupled to said sixteenth bidirectional group of power semiconductors, wherein the first phase of the induction motor is coupled in series between the center taps of said first and fourth balance coils; l) a fifth balance coil having a center tap, a firs branch coupled to said eleventh bidirectional group of power semiconductors, a second branch coupled to said fourteenth bidirectional group of power semiconductors and a third branch coupled to said seventeenth bidirectional group of power semiconductors, wherein the second phase of the induction motor is coupled in series between the center tap of said second and fifth balance coils; and m) a sixth balance coil having a center tap, a first branch coupled to said twelfth bidirectional group of power semiconductors, sa second branch coupled to said fifteenth bidirectional group- of power semiconductors and a third branch coupled to said eighteenth bidirectional group of power semiconductors, wherein the third phase of the induction motor is coupled in series between said third and sixth balance coils, and the first, second and third phase of the induction motor are not a connected to each other but rather form a virtual star point.

Claim 24

The three-phase converter according to claim 20, further comprising a controller controlling the first through eighteenth bidirectional groups of power semiconductors, whereby said controller activates the power semiconductors in sequence with overlapping ignition pulses.

Claim 25

The three-phase converter according to claim 21, wherein the overlapping ignition pulses are achieved by maintaining the power semiconductors ready to engage and activating them before a calculated current zero crossing.

Claim 26

The three-phase converter according to claim 20, wherein the first through sixth secondary windings are nested into a single coil.

Claim 27

The three-phase converter according to claim 21, wherein the first through sixth secondary windings are nested into a single coil.

Claim 28

The three-phase conveter according to claim 22, wherein the first through sixth secondary windings are nested into a single coil.