Current sharing power supplies with redundant operation

Claim 2

A redundant mode power supply comprising: a power stage having an error signal as input and producing as output a voltage proportional to said error signal; a variable resistance element connected between said power stage output and a power supply output, said variable resistance element having a lower resistance for high currents passing through said variable resistance element and a higher resistance for a minimum current passing through said variable resistance element; an error amplifier producing said error signal in proportion to a gain constant multiplied by the difference between a reference voltage and said power supply output voltage, said error amplifier having a gain constant with a value of A.sub.fzr ≦I.sub.min R.sub.d /|Voa-Vout| where A fzr is said error amplifier gain constant, R d is a resistance of said variable resistance element resistance at a maximum output current, |Voa-Vout| is a absolute value of a difference between said power stare output voltage and said power supply output at said minimum load current, I min is said minimum load current.

Claim 3

The power supply of claim 1 wherein said variable resistance element is a semiconductor device.

Claim 4

The power supply of claim 2 wherein said semiconductor device is a diode.

Claim 5

The power supply of claim 1 wherein said variable resistance element is a material having a negative temperature coefficient.

Claim 6

A plurality 2 to n of redundant mode power supplies connected in a parallel configuration and having a common power supply output, each power supply j comprising: a power stage having an error signal as input and producing as output a voltage proportional to said error signal; a variable resistance element connected between said power stage output and said power supply output, said variable resistance element having a lower resistance for high currents passing through said variable resistance element and a higher resistance for low currents passing through said variable resistance element; an error amplifier producing said error signal in proportion to a gain constant multiplied by the difference between a reference voltage and said power supply output voltage, said gain constant having a value of A.sub.fzr ≦Imin Rd/|Vo(j)-Vo| where A fzr is said error amplifier gain constant, R d is a resistance of said variable resistance element resistance at a maximum output current, |Vo(j)-Vo(mean)| is an absolute value of a difference between said power stage output voltage of said power supply j and a power supply output voltage at said minimum load current, and I min is said minimum load current.

Claim 7

A plurality 2 to n of redundant mode power supplies connected in a parallel configuration and having a common power supply output, each power supply j comprising: a power stage having an error signal as input and producing as output a voltage proportional to said error signal; a variable resistance element connected between said power stage output and said power supply output, said variable resistance element having a lower resistance for high currents passing through said variable resistance element and a higher resistance for low currents passing through said variable resistance element; an error amplifier producing said error signal in proportion to a gain constant multiplied by the difference between a reference voltage and said power supply output voltage, said gain constant having a value of A.sub.fzr ≦Imin Rd/|Vo(j)-Vo| where A fzr is said error amplifier gain constant, R d is a resistance of said variable resistance element resistance at a maximum output current, |Vo(j)-Vo(mean)| is an absolute value of a difference between said power stage output voltage of said power supply j and a power supply output voltage at said minimum load current, and I min is said minimum load current.

Claim 8

The power supply of claim 5 wherein said variable resistance element is a semiconductor device.

Claim 9

The power supply of claim 6 wherein said semiconductor device is a diode.

Claim 10

The power supply of claim 5 wherein said variable resistance element is a material having a negative temperature coefficient.

Claim 11

A redundant mode power supply having a single output voltage and comprising: a plurality n of power stages having an error signal as input and producing as output a voltage proportional to said error signal, each of said power stages having a gain P i where n is larger than two, and i is an index having a value from 2 to n; a plurality n of variable resistance elements connected between each of said power stage output and said single output voltage, said variable resistance elements having a lower resistance for high currents passing through said variable resistance element and a higher resistance for low currents passing through said variable resistance element; a plurality n of error amplifiers each having a reference voltage, said error amplifiers producing n said error signals in proportion to a gain constant K i multiplied by a difference between said reference voltage and said power supply output voltages, each of said error amplifiers individually providing said error signal to each of said power stages; said output stage gain constants P i and said error amplifier gain constant K i are chosen such that Zo.sub.i ≦P.sub.i K.sub.i |Vo.sub.i -Vout|/Imin where Zo i is an output impedance of each of n said power stages operating at a minimum power stage output current added to a resistance of each of i said variable resistance elements operating at a minimum power stage output current, |Vo i -Vout| is an absolute value of a difference between said power stage n output voltage and said output voltage at said minimum power stage output current, and Imin is a minimum load current, equal to a sum of each of n said minimum power stage output currents.

Claim 12

A redundant mode power supply having a single output voltage and comprising: a plurality n of power stages having an error signal as input and producing as output a voltage proportional to said error signal, each of said power stages having a gain P i where n is larger than two, and i is an index having a value from 2 to n; a plurality n of variable resistance elements connected between each of said power stage output and said single output voltage, said variable resistance elements having a lower resistance for high currents passing through said variable resistance element and a higher resistance for low currents passing through said variable resistance element; a plurality n of error amplifiers each having a reference voltage, said error amplifiers producing n said error signals in proportion to a gain constant K i multiplied by a difference between said reference voltage and said power supply output voltages, each of said error amplifiers individually providing said error signal to each of said power stages; said output stage gain constants P i and said error amplifier gain constant K i are chosen such that Zo.sub.i ≦P.sub.i K.sub.i |Vo.sub.i -Vout|/Imin where Zo i is an output impedance of each of n said power stages operating at a minimum power stage output current added to a resistance of each of i said variable resistance elements operating at a minimum power stage output current, |Vo i -Vout| is an absolute value of a difference between said power stage n output voltage and said output voltage at said minimum power stage output current, and Imin is a minimum load current, equal to a sum of each of n said minimum power stage output currents.

Claim 13

The power supply of claim 9 wherein said variable resistance element is a semiconductor device.

Claim 14

The power supply of claim 10 wherein said semiconductor device is a diode.

Claim 15

The power supply of claim 9 wherein said variable resistance element is a material having a negative temperature coefficient.