Zero voltage switching supplies connected in parallel

Claim 2

A composite power supply comprising: a master ZVS power supply comprising a first ZVS switch with (a) a first switch control to turn off said first switch based on a comparison of a voltage corresponding to the load voltage or current and an output error voltage and (b) a second switch control to turn on said first switch when a voltage across said first switch is approximately zero volts; a slave ZVS power supply comprising a second ZVS switch with (c) a third switch control to turn off said second switch based on a comparison of a voltage corresponding to the load voltage or current and a reference voltage and (d) a fourth switch control to turn on said second switch when a voltage across said second switch is approximately zero volts; and means for producing a pulse-width-modulated ("PWM") signal having a duty cycle corresponding to an actual phase angle between the switching-on of said first switch and the switching-on of said second switch; an averaging or integrating circuit for receiving said PWM signal and generating an adjustment signal having a magnitude proportional to a phase difference between (i) a pre-determined phase angle between the switching of said first and second switches (ii) the actual phase angle between the switching of said first and second switches; and means for summing said first reference voltage with said adjustment signal, said summing means having an output providing said reference voltage for said slave ZVS power supply to thereby minimize said phase difference.

Claim 3

A composite power supply as set forth in claim 1 wherein said master power supply is a buck power supply and said slave power supply is a buck power supply.

Claim 4

A composite power supply as set forth in claim 2 wherein an output of said master power supply is connected to an output of said slave power supply.

Claim 5

A composite power supply as set forth in claim 2 wherein said master power supply and said slave power supply are variable frequency.

Claim 6

A composite power supply as set forth in claim 2 wherein said predetermined phase angle equals a total number of power supplies in said composite power supply divided into 360 degrees.

Claim 7

A composite power supply as set forth in claim 2 wherein said output error voltage is a difference between a voltage corresponding to the load voltage and a fixed reference voltage which difference signifies the maximum permissible deviation of the load voltage from a nominal value.

Claim 8

A composite power supply as set forth in claim 2 wherein said PWM signal means comprises a flip flop coupled to receive said first and third switch controls as inputs.

Claim 9

A composite power supply as set forth in claim 2 wherein said master power supply comprises a capacitor in parallel with an output of said master power supply and comprises an inductor in series with said output, and said first switch is in series with said inductor.

Claim 10

A composite power supply as set forth in claim 2, including a plurality of said slave power supplies wherein said pre-determined phase angle between the switching of said master power supply and the switching of a given ZVS slave power supply is selected from the set of M*360/N degrees, M=1. . . N-1, where M is an integer, N is the total number of power supplies, and no two slave ZVS power supplies have the same phase relationship with respect to the master power supply.

Claim 11

A composite power supply as set forth in claim 8 wherein said second switch control comprises a first comparator having inputs connected across said first switch and said first switch control comprises a second comparator having inputs connected to respond to said load current or load voltage, the outputs of said first and second comparators turning on said first switch when said first switch exhibits approximately zero volts and turning off said first switch when the load current or voltage exhibits a predetermined level.

Claim 12

A composite power supply as set forth in claim 10 wherein said master power supply further comprises a flip flop having input s coupled to receive outputs of said first and second comparators and having an output coupled to control said first switch.

Claim 13

A composite power supply as set forth in claim 10 wherein said third switch control comprises a third comparator having inputs connected across said second switch and said fourth switch control comprises a fourth comparator having inputs connected to respond to a load current or load voltage, the outputs of said third and fourth comparators turning on said second switch when said second switch exhibits approximately zero volts and turning off said second switch when the load current or voltage exhibits a predetermined level.

Claim 14

A composite power supply comprising: a master ZVS power supply comprising a first switch with (a) first switch control to turn off said first switch based on a comparison of a first output error voltage and a first reference voltage provided across a first capacitor which is charged by a first current source and (b) a second switch control to turn on said first switch when a voltage across said first switch is approximately zero volts; a slave ZVS power supply comprising a second switch with (c) a third switch control to turn off said second switch based on a comparison of a second output error voltage and a second reference voltage provided across a second capacitor which is charged by a second current source and (d) a fourth switch control to turn on said second switch when a voltage across said second switch is approximately zero volts; means for producing a pulse-width-modulated ("PWM") signal having a duty cycle corresponding to an actual phase angle between the switching-on of said first switch and the switching-on of said second switch; an averaging or integrating circuit for receiving said PWM signal and generating an adjustment signal having a magnitude proportional to a phase difference between (i) a pre-determined phase angle between the switching of said first and second switches and (ii) the actual phase angle between the switching of said first and second switches; and means for increasing or decreasing charging current to said second capacitor in proportion to the magnitude of said adjustment signal in order to minimize said phase difference.

Claim 15

A composite power supply comprising: a master ZVS power supply comprising a first switch with (a) first switch control to turn off said first switch based on a comparison of a first output error voltage and a first reference voltage provided across a first capacitor which is charged by a first current source and (b) a second switch control to turn on said first switch when a voltage across said first switch is approximately zero volts; a slave ZVS power supply comprising a second switch with (c) a third switch control to turn off said second switch based on a comparison of a second output error voltage and a second reference voltage provided across a second capacitor which is charged by a second current source and (d) a fourth switch control to turn on said second switch when a voltage across said second switch is approximately zero volts; means for producing a pulse-width-modulated ("PWM") signal having a duty cycle corresponding to an actual phase angle between the switching-on of said first switch and the switching-on of said second switch; an averaging or integrating circuit for receiving said PWM signal and generating an adjustment signal having a magnitude proportional to a phase difference between (i) a pre-determined phase angle between the switching of said first and second switches and (ii) the actual phase angle between the switching of said first and second switches; and means for increasing or decreasing charging current to said second capacitor in proportion to the magnitude of said adjustment signal in order to minimize said phase difference.

Claim 16

A composite power supply as set forth in claim 13 wherein said master power supply is a boost power supply and said slave power supply is a boost power supply.

Claim 17

A composite power supply as set forth in claim 14 wherein said PWM signal means comprises a flip flop coupled to receive said first and third switch controls as inputs, an output of said flip flop being coupled to an input of said averaging or integrating circuit.

Claim 18

A composite power supply as set forth in claim 14 wherein an output of said master power supply is connected to an output of said slave power supply.

Claim 19

A composite power supply as set forth in claim 14 wherein said master power supply and said slave power supply are variable frequency.

Claim 20

A composite power supply as set forth in claim 14, including a plurality of said slave power supplies wherein said pre-determined phase angle between the switching of said master power supply and the switching of a given ZVS slave power supply is selected from the set of M*360/N degrees, M=1. . . N-1, where M is an integer, N is the total number of power supplies, and no two slave ZVS power supplies have the same phase relationship with respect to the master power supply.

Claim 21

The composite power supply according to claim 14 wherein said first and second output error voltages are the same and equal to a feedback error voltage which signifies the maximum permissible deviation of the load voltage from a nominal value.

Claim 22

A composite power supply, comprising: a master ZVS power supply comprising a first switch with (a) a first switch control to open or turn off said first switch based on a comparison of (i) a voltage corresponding to a first ramp signal and (ii) a first reference voltage, and (b) a second switch control to turn on said first switch when a voltage across said first switch is approximately zero volts; a slave ZVS power supply comprising a second switch with (c) a third switch control to open or turn off said second switch based on a comparison of (i) a voltage corresponding to a second ramp signal and (i) a second reference voltage and (d) a fourth switch control to turn on said second switch when a voltage across said second switch is approximately zero volts; means for producing a signal which is substantially balanced when an actual phase angle between the switching-on of said first switch and the switching-on of said second switch substantially equals a pre-determined phase angle and is unbalanced otherwise; an averaging or integrating circuit for receiving said balanced/unbalanced signal and generating an adjustment signal indicative of a phase difference between (i) said actual phase angle between the switching of said first and second switches and (ii) said pre-determined phase angle; and means for adjusting said second ramp signal or said second reference voltage in accordance with said adjustment signal in order to reduce said phase difference and substantially maintain the switching of said first and second switches at said pre-determined phase angle.

Claim 23

A composite power supply, comprising: a master ZVS power supply comprising a first switch with (a) a first switch control to open or turn off said first switch based on a comparison of (i) a voltage corresponding to a first ramp signal and (ii) a first reference voltage, and (b) a second switch control to turn on said first switch when a voltage across said first switch is approximately zero volts; a slave ZVS power supply comprising a second switch with (c) a third switch control to open or turn off said second switch based on a comparison of (i) a voltage corresponding to a second ramp signal and (i) a second reference voltage and (d) a fourth switch control to turn on said second switch when a voltage across said second switch is approximately zero volts; means for producing a signal which is substantially balanced when an actual phase angle between the switching-on of said first switch and the switching-on of said second switch substantially equals a pre-determined phase angle and is unbalanced otherwise; an averaging or integrating circuit for receiving said balanced/unbalanced signal and generating an adjustment signal indicative of a phase difference between (i) said actual phase angle between the switching of said first and second switches and (ii) said pre-determined phase angle; and means for adjusting said second ramp signal or said second reference voltage in accordance with said adjustment signal in order to reduce said phase difference and substantially maintain the switching of said first and second switches at said pre-determined phase angle.

Claim 24

The composite power supply according to claim 20 wherein the means for producing said balanced/unbalanced signal comprises a means for producing a pulse-width-modulated ("PWM") signal having a duty cycle corresponding to an actual phase angle between the switching-on of said first switch and the switching-on of said second switch.

Claim 25

The composite power supply according to claim 21, wherein said PWM signal means comprises a flip flop coupled to receive said first and third switch controls as inputs.

Claim 26

The composite power supply according to claim 21, wherein said averaging or integrating circuit generates an adjustment signal whose magnitude is proportional to said phase difference between (i) said actual phase angle between the switching of said first and second switches and (ii) said pre-determined phase angle.

Claim 27

The composite power supply according to claim 20 wherein: (a) said master and slave ZVS power supplies are buck-type power supplies; (b) said first ramp signal corresponds to a fluctuating load voltage or current and said second ramp signal corresponds to a fluctuating load voltage or current; and (c) said adjustment means comprises a summing circuit for summing said first reference voltage with said adjustment signal, said summing means having an output which provides said second reference voltage.

Claim 28

The composite power supply according to claim 24, wherein said first and second ramp signals are substantially equal.

Claim 29

The composite power supply according to claim 20, wherein: (a) said master and slave ZVS power supplies are boost-type power supplies; (b) said first and second ramp signals are provided by first and second capacitors which are charged by respective first and second current sources; and (c) said adjustment means comprises a means for increasing and decreasing the charging current to said second capacitor.

Claim 30

The composite power supply according to claim 20, wherein said first and second reference voltages are substantially equal.