Power converter apparatus and method employing plural branches

Claim 2

A converter wherein DC is converted to AC in response to a gradually changing control source comprising N series connected taps at N DC voltages having different absolute values, where N is an integer greater than one, N branch circuits, branch circuit k being connected to tap k, where k is selectively one through N, branch circuit k including variable response means responsive to the control source so that branch circuit k is conducting to the exclusion of all other branch circuits in response to the control source amplitude being in a predetermined range, the variable response means of branch circuit k while conducting having an output with a gradually changing envelope between the voltage at tap k and the voltage at a tap adjacent tap k in response to the gradual changes of the source so that each branch while conducting dissipates the same amount of energy, and means for combining the outputs from the N branches.

Claim 3

2 . A converter wherein DC is converted to AC in response to a gradually changing control source having first and second opposite polarity amplitude variations about an average value, comprising N series connected taps at N DC voltages having different absolute values, where N is an integer greater than one, N branch circuits, branch circuit k being connected to tap k, where k is selectively one through N, branch circuit k including variable response means responsive to the control source so that branch circuit k is conducting to the exclusion of all other branch circuits in response to the control source amplitude being in a predetermined range, the variable response means of branch circuit k while conducting having an output with a gradually changing envelope between the voltage at tap k and the voltage at a tap adjacent tap k in response to the gradual changes of the source, branch circuit g including an emitter collector path of a transistor having a control electrode coupled to the control source, one electrode of the path of branch circuit g being connected to tap g, where g is selectively every integer from one to N, another of the electrodes of the path of branch circuit g being connected to the output of branch circuit g via diode means for preventing output current from another branch circuit from flowing to branch circuit g when the amplitude of the control source is above the range for branch circuit h to conduct, where h is selectively every integer from 1 to (N-1), a transformer having a winding with a center tap connected to be responsive to current flowing in each branch, and switch means for connecting opposite first and second terminals of the winding to a reference potential at mutually exclusive times so current flows between the first terminal and the branch circuits during the first polarity variation and current flows between the second half and the branch circuits during the second polarity variation, the transformer having an output winding responsive to the current flowing through the first and second terminals of the winding.

Claim 4

2 . A converter wherein DC is converted to AC in response to a gradually changing control source having first and second opposite polarity amplitude variations about an average value, comprising N series connected taps at N DC voltages having different absolute values, where N is an integer greater than one, N branch circuits, branch circuit k being connected to tap k, where k is selectively one through N, branch circuit k including variable response means responsive to the control source so that branch circuit k is conducting to the exclusion of all other branch circuits in response to the control source amplitude being in a predetermined range, the variable response means of branch circuit k while conducting having an output with a gradually changing envelope between the voltage at tap k and the voltage at a tap adjacent tap k in response to the gradual changes of the source, branch circuit g including an emitter collector path of a transistor having a control electrode coupled to the control source, one electrode of the path of branch circuit g being connected to tap g, where g is selectively every integer from one to N, another of the electrodes of the path of branch circuit g being connected to the output of branch circuit g via diode means for preventing output current from another branch circuit from flowing to branch circuit g when the amplitude of the control source is above the range for branch circuit h to conduct, where h is selectively every integer from 1 to (N-1), a transformer having a winding with a center tap connected to be responsive to current flowing in each branch, and switch means for connecting opposite first and second terminals of the winding to a reference potential at mutually exclusive times so current flows between the first terminal and the branch circuits during the first polarity variation and current flows between the second half and the branch circuits during the second polarity variation, the transformer having an output winding responsive to the current flowing through the first and second terminals of the winding.

Claim 5

An uninterrupted AC power supply powered oy an AC source subject to being interrupted comprising an AC to DC converter including means for maintaining a substantially constant DC power supply voltage while the AC power source is interrupted for up to several cycles, a DC to AC converter powered by the substantially constant DC power supply voltage of the AC to DC converter, said DC to AC converter including: a gradually changing control source, N series connected taps at N DC voltages having different absolute values, where N is an integer greater than one, N branch circuits, branch circuit k being connected to tap k, where k is selectively one through N, branch circuit k including variable response means responsive to the control source so that branch circuit k is conducting to the exclusion of all other branch circuits in response to the control source amplitude being in a predetermined range, the variable response means of branch circuit k while conducting having an output with a gradually changing envelope between the voltage at tap k and the voltage at a tap adjacent tap k in response to the gradual changes of the source, and means for combining the outputs from the N branches. through N, branch circuit k including variable response means responsive to the control source so that branch circuit k is conducting to the exclusion of all other branch circuits in response to the control source amplitude being in a predetermined range, the variable response means of branch circuit k while conducting having an output with a gradually-changing envelope between the voltage at tap k and the voltage at a tap adjacent tap k in response to the gradual changes of the source, and means for combining the outputs from the N branches.

Claim 6

An uninterrupted AC power supply powered oy an AC source subject to being interrupted comprising an AC to DC converter including means for maintaining a substantially constant DC power supply voltage while the AC power source is interrupted for up to several cycles, a DC to AC converter powered by the substantially constant DC power supply voltage of the AC to DC converter, said DC to AC converter including: a gradually changing control source, N series connected taps at N DC voltages having different absolute values, where N is an integer greater than one, N branch circuits, branch circuit k being connected to tap k, where k is selectively one through N, branch circuit k including variable response means responsive to the control source so that branch circuit k is conducting to the exclusion of all other branch circuits in response to the control source amplitude being in a predetermined range, the variable response means of branch circuit k while conducting having an output with a gradually changing envelope between the voltage at tap k and the voltage at a tap adjacent tap k in response to the gradual changes of the source, and means for combining the outputs from the N branches. through N, branch circuit k including variable response means responsive to the control source so that branch circuit k is conducting to the exclusion of all other branch circuits in response to the control source amplitude being in a predetermined range, the variable response means of branch circuit k while conducting having an output with a gradually-changing envelope between the voltage at tap k and the voltage at a tap adjacent tap k in response to the gradual changes of the source, and means for combining the outputs from the N branches.

Claim 7

The power supply of claim 1, 2 or 3 wherein the voltage and current applied to each branch circuit and the conducting time of each branch circuit are such that the energy dissipated in each branch circuit is approximately the same.

Claim 8

The converter of claim 1, 2 or 3 wherein the control source is a sinusoid, the phase angle, 6, when branch k changes from a conducting to a non-conducting state, and the phase angle θ k-1 when branch k begins to conduct being such that sinθ k cos k-1 (sin2θ k +sin2 θk-1 ) is the same for each branch.

Claim 9

The power supply of claim 3 wherein branch circuit g includes an emitter collector path of a transistor having a control electrode coupled to the control source, one electrode of the path of branch circuit g being connected to tap g, where g is selectively every integer from one to N, another of the electrodes of the path of branch circuit g being connected to the output of branch circuit g via diode means for preventing output current from another branch circuit from flowing to branch circuit & when the amplitude of the control source is above the range for branch h to conduct, where h is selectively every integer from 1 to (N-1).

Claim 10

7 . The power supply of claim 6 wherein the control source has first and second opposite polarity variations about an average value, and further including a transformer having a winding with a center tap connected to be responsive to current flowing in each branch, and switch means for connecting opposite first and second terminals of the winding to a reference potential at mutually exclusive times so current flows between the first terminal and the branch circuits during the first polarity variations and current flows between the second terminal and the branch circuits during the second polarity variation, the transformer having an output winding responsive to the current flowing in the first and second terminals of the winding.

Claim 13

The method of claim 8 wherein the predetermined waveform is sinusoidal.

Claim 14

10 . The method of claim 9 wherein the phase angle, θ k when branch k changes from a conducting to a non-conducting state, and the phase angle θ k-1 when branch k begins to conduct is such that sinθ k cosθ k-1 sin2θ k +sin2θ k-1 ) is the same for each branch.