Energy recovery circuit for inverters

Claim 2

In an inverter in combination, a positive bus, a negative bus, an AC bus, load circuit means, first switch means for controlling the flow of current between said positive bus and said load circuit means through said AC bus, second switch means for controlling the flow of current between said negative bus and said load circuit means through said AC bus, a commutating transformer having first and second windings on a magnetic core, means for connecting said first and second switch means between said positive and negative busses through respective windings of said commutating transformer, first and second capacitance means, means for connecting said capacitance means in series between said positive and negative busses, means for connecting the junction of said capacitance means to said switch means, means for alternately and severally energizing said first and second switch means, a discharge inductor comprising a winding on another magnetic core, means for connecting the charged one of said capacitance means in closed circuit relationship with one of the windings of said commutating transformer and means for connecting the uncharged one of said capacitance means in closed circuit, current conducting relationship with the other of the windings of said commutating transformer and said discharge inductor.

Claim 3

In an inverter, in combination, a positive bus, a negative bus, an AC bus, load circuit means, first switch means for controlling the flow of current between said positive bus and said load circuit means through said AC bus, second switch means for controlling the flow of current between said negative bus and said load circuit means through said AC bus, first and second capacitance means, means for connecting said capacitance means in series between said positive and negative busses, means for connecting the junction of said capacitance means to said switch means, a commutating transformer having first and second windings on a magnetic core, means for connecting said first and second switch means between said positive and negative busses through respective windings of said commutating transformer, means for alternately and severally energizing said first and second switch means, a discharge inductor comprising a winding on another magnetic core, a first discharge loop for conducting discharge current through said first winding and through said first switch means when said first capacitance means discharges. A first charging loop for conducting charging current through said second winding said discharge inductor and said second capacitance means when said first capacitance means discharges, a second discharge loop for conducting discharge current through said second winding and through said second switch means when said second capacitance means discharges, a second charging loop for conducting charging current through said first winding, said discharge inductor and said first capacitance means when said second capacitance means discharges, said commutating transformer serving to transfer energy between said charging and discharge loops.

Claim 4

In an inverter, in combination, a positive bus, a negative bus, an AC bus, load circuit means, first switch means for controlling the flow of current between said positive bus and said load circuit means through said AC bus, second switch means for controlling the flow of current between said negative bus and said load circuit means through said AC bus, first and second capacitance means, means for connecting said capacitance means in series between said positive and negative busses, means for connecting the junction of said capacitance means to said switch means, a commutating transformer having first and second windings on a magnetic core, means for connecting said first and second switch means between said positive and negative busses through respective windings of said commutating transformer, means for alternately and severally energizing said first and second switch means, a discharge inductor comprising a winding on another magnetic core, a first discharge loop for conducting discharge current through said first winding and through said first switch means when said first capacitance means discharges. A first charging loop for conducting charging current through said second winding said discharge inductor and said second capacitance means when said first capacitance means discharges, a second discharge loop for conducting discharge current through said second winding and through said second switch means when said second capacitance means discharges, a second charging loop for conducting charging current through said first winding, said discharge inductor and said first capacitance means when said second capacitance means discharges, said commutating transformer serving to transfer energy between said charging and discharge loops.

Claim 5

In an inverter, in combination, a positive buS, a negative bus, a neutral bus electrically between said positive and negative busses, first and second switch means each having power circuit means and control circuit means, a commutating transformer having first and second windings on one magnetic core, means for connecting said first and second switch means between said positive and negative busses through respective windings of said commutating transformer, load circuit means, means for connecting said load circuit means between said neutral bus and the power circuit means of said switch means, first and second commutating capacitance means, means for connecting said commutating capacitance means in series between said positive and negative busses, means for connecting the junction between said capacitance means to the power circuit means of said switch means, means for alternately and severally energizing the control circuit means of said first and second switch means, a discharge inductor comprising a winding on another magnetic core, said discharge inductor serving as means for transferring energy from the discharging one of said capacitance means to the charging one of said capacitance means, means for connecting said discharge inductor in closed circuit relationship with the charging one of said capacitance means through the conducting one of said switch means, unidirectional conducting means, means for connecting said unidirectional conducting means in series with said discharge inductor.

Claim 6

In an inverter, in combination, a positive buS, a negative bus, a neutral bus electrically between said positive and negative busses, first and second switch means each having power circuit means and control circuit means, a commutating transformer having first and second windings on one magnetic core, means for connecting said first and second switch means between said positive and negative busses through respective windings of said commutating transformer, load circuit means, means for connecting said load circuit means between said neutral bus and the power circuit means of said switch means, first and second commutating capacitance means, means for connecting said commutating capacitance means in series between said positive and negative busses, means for connecting the junction between said capacitance means to the power circuit means of said switch means, means for alternately and severally energizing the control circuit means of said first and second switch means, a discharge inductor comprising a winding on another magnetic core, said discharge inductor serving as means for transferring energy from the discharging one of said capacitance means to the charging one of said capacitance means, means for connecting said discharge inductor in closed circuit relationship with the charging one of said capacitance means through the conducting one of said switch means, unidirectional conducting means, means for connecting said unidirectional conducting means in series with said discharge inductor.

Claim 7

In an inverter, in combination, a positive bus, a negative bus, a neutral bus electrically between said positive and negative busses, first and second switch means each having power circuit means and control circuit means, load circuit means, a commutating transformer having first and second windings on a first magnetic core, means for connecting said first winding and the power circuit means of said first switch means in series between one end of said load circuit means and said positive bus, means for connecting said second winding and the power circuit means of said second switch means in series between said one end of said load circuit means and said negative bus, means for connecting said load circuit means to said neutral bus, first and second commutating capacitance means, means for connecting said first and second commutating capacitance means in series between said positive bus and said negative bus, means for connecting the junction of said capacitance means to said switch means, means for alternately and severally energizing the control circuit means of said first and second switch means, a discharge inductor comprising a winding on a second magnetic core, means for connecting said discharge inductor across the power circuit means of said first and second switch means, unidirectional conducting means and means for connecting said unidirectional conducting means in series with said discharge inductor.

Claim 8

In an inverter, in combination, a positive bus, a negative bus, a neutral bus electrically between said positive and negative busses, first and second switch means each having power circuit means and control circuit means, load circuit means, a commutating transformer having first and second windings on a first magnetic core, means for connecting said first winding and the power circuit means of said first switch means in series between one end of said load circuit means and said positive bus, means for connecting said second winding and the power circuit means of said second switch means in series between said one end of said load circuit means and said negative bus, means for connecting said load circuit means to said neutral bus, first and second commutating capacitance means, means for connecting said first and second commutating capacitance means in series between said positive bus and said negative bus, means for connecting the junction of said capacitance means to said switch means, means for alternately and severally energizing the control circuit means of said first and second switch means, a discharge inductor comprising a winding on a second magnetic core, means for connecting said discharge inductor across the power circuit means of said first and second switch means, unidirectional conducting means and means for connecting said unidirectional conducting means in series with said discharge inductor.

Claim 9

In an inverter, in combination, a positive bus, a negative bus, a plurality of single phase inverters, means for connecting each of said single phase inverters to said positive and negative busses; each of said single phase inverters including first and second wingings on a magnetic core, means for connecting said first and second switch means a commutating transformer having first and second switch means between said positive and negative busses through said first and second windings, means for alternately and severally energizing said first an second switch means, first and second capacitance means, means for connecting said capacitance means in series between said positive and negative busses, means for connecting the junction of said capacitance means to said switch means, a discharge inductor for transferring energy from the discharging one of said capacitance means to the charging one of said capacitance means, said discharge inductor comprising a winding on another magnetic core, means for connecting one end of said discharge inductor to the junction between said first switch mean and said first winding, meanS for connecting the other end of said discharge inductor to the junction between said second switch means and said second winding, unidirectional conducting means, means for connecting said unidirectional conducting means in series with said discharge inductor; polyphase load means having a plurality of polyphase terminal means, means for connecting each of said polyphase terminal means to the first and second switch means of a respective single phase inverter.

Claim 10

In an inverter, in combination, a positive bus, a negative bus, a plurality of single phase inverters, means for connecting each of said single phase inverters to said positive and negative busses; each of said single phase inverters including first and second wingings on a magnetic core, means for connecting said first and second switch means a commutating transformer having first and second switch means between said positive and negative busses through said first and second windings, means for alternately and severally energizing said first an second switch means, first and second capacitance means, means for connecting said capacitance means in series between said positive and negative busses, means for connecting the junction of said capacitance means to said switch means, a discharge inductor for transferring energy from the discharging one of said capacitance means to the charging one of said capacitance means, said discharge inductor comprising a winding on another magnetic core, means for connecting one end of said discharge inductor to the junction between said first switch mean and said first winding, meanS for connecting the other end of said discharge inductor to the junction between said second switch means and said second winding, unidirectional conducting means, means for connecting said unidirectional conducting means in series with said discharge inductor; polyphase load means having a plurality of polyphase terminal means, means for connecting each of said polyphase terminal means to the first and second switch means of a respective single phase inverter.

Claim 11

In an inverter, in combination, a positive bus, a negativ bus, a neutral bus electrically between said positive and negative busses, first and second switch means, a commutating transformer having first and second coupled windings on a magnetic core, means for connecting said first switch means to said positive bus through said first winding, means for connecting said second switch means to said negative bus through said second winding, means for connecting said first and second switch means, load circuit means, means for connecting said load circuit means between said neutral bus and first and second switch means, means for alternately and severally energizing said switch means, first and second capacitance means, means for connecting said capacitance means in series between said positive and negative busses, means for connecting the junction of said capacitance means to said switch means, a discharge inductor, said discharge inductor comprising a winding on another magnetic core, means for connecting one end of said discharge inductor to the junction between said first switch means and said first winding, means for connecting the other end of said discharge inductor to the junction between said second switch means and said second winding, unidirectional conducting means, and means for connecting said unidirectional conducting means in series with said discharge inductor.

Claim 12

In an inverter, in combination, a positive bus, a negativ bus, a neutral bus electrically between said positive and negative busses, first and second switch means, a commutating transformer having first and second coupled windings on a magnetic core, means for connecting said first switch means to said positive bus through said first winding, means for connecting said second switch means to said negative bus through said second winding, means for connecting said first and second switch means, load circuit means, means for connecting said load circuit means between said neutral bus and first and second switch means, means for alternately and severally energizing said switch means, first and second capacitance means, means for connecting said capacitance means in series between said positive and negative busses, means for connecting the junction of said capacitance means to said switch means, a discharge inductor, said discharge inductor comprising a winding on another magnetic core, means for connecting one end of said discharge inductor to the junction between said first switch means and said first winding, means for connecting the other end of said discharge inductor to the junction between said second switch means and said second winding, unidirectional conducting means, and means for connecting said unidirectional conducting means in series with said discharge inductor.

Claim 13

In an inverter, in combination a positive bus, a negative bus, a neutral bus electrically between said positive and negative busses, first and second switch means, a commutating transformer having a center-tapped winding on a magnetic core, means for connecting said center-tapped winding between said positive and negative busses through said first and second switch means, load circuit means, means for connecting said load circuit means between said neutral bus and the center-tap of said commutating transformer, first and second commutating capacitance means, means for connecting said first capacitance means between said positive bus and center tap of said commutating transformer, means for connecting said second capacitance means between said negative bus and the center-tap of said commutating transformer, means for alternately and severally energizing said first and second switch means, first and second discharge inductors, each of said discharge inductors comprising a winding on a respective magnetic core, means for connecting said first discharge inductor between said positive bus and the junction between said first switch means and said commutating transformer, means for connecting said second discharge inductor between said negative bus and the junction between said second switch means and said commutating transformer, unidirectional conducting means and means for connecting said unidirectional conducting means in series with said discharge inductors.

Claim 14

In an inverter, in combination a positive bus, a negative bus, a neutral bus electrically between said positive and negative busses, first and second switch means, a commutating transformer having a center-tapped winding on a magnetic core, means for connecting said center-tapped winding between said positive and negative busses through said first and second switch means, load circuit means, means for connecting said load circuit means between said neutral bus and the center-tap of said commutating transformer, first and second commutating capacitance means, means for connecting said first capacitance means between said positive bus and center tap of said commutating transformer, means for connecting said second capacitance means between said negative bus and the center-tap of said commutating transformer, means for alternately and severally energizing said first and second switch means, first and second discharge inductors, each of said discharge inductors comprising a winding on a respective magnetic core, means for connecting said first discharge inductor between said positive bus and the junction between said first switch means and said commutating transformer, means for connecting said second discharge inductor between said negative bus and the junction between said second switch means and said commutating transformer, unidirectional conducting means and means for connecting said unidirectional conducting means in series with said discharge inductors.