Multi-phase and multi-module power system with a current share bus

• US 20040217741A1
• Filed: 04/29/2003
• Published: 11/04/2004
• Est. Priority Date: 04/29/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Muratov, Vladimir Alexander, Wiktor, Stefan Wlodzimierz
• Granted Patent: US 6,850,045 B2
• Time in Patent Office: Days
• US Class Current: 323/219
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel

Abstract

A pulse width modulator (305) for driving a load in a multi-phased power system having circuitry (270) responsive to channel signals for providing an average signal by summing the channel signals at a node (221) which is coupled with a plurality of resistive elements, and having further circuitry for providing an error between said load and said reference potential, and having still further circuitry (250) for summing the channel signals, average signal, and error for providing a respective drive signal for each of the power switches, wherein the error signal and the average signal have complementary effects on a duty factor of the drive signals and the channel signal has an effect contrary to the error signal and the average signal. Further, a plurality of pulse width modulators (305) can be combined as a system (300) by connecting respective nodes (221) for providing current sharing between all phases.

Claims

1. A pulse width modulator for driving a load in a multi-phased power system, each phase having a power switch for selectively coupling a corresponding inductor to a source and said load, said multi-phased power system further including a sensor for sensing a channel current in each said phase and providing a plurality of signals each representative of a corresponding channel current, said pulse width modulator comprising:

first circuitry coupled with said sensor for receiving said channel signals and responsive thereto for providing an average signal by summing said channel signals at a node coupled with a plurality of resistive elements corresponding to the number of phases of said multi-phased power system, wherein said average signal is detectable in one of said resistive elements, each said resistive elements having substantially the same resistivity;

second circuitry coupled with said load and a reference potential and responsive thereto for providing a signal representative of an error between said load and said reference potential; and

third circuitry coupled with said sensor, said first circuitry, and said second circuitry for receiving said channel signals, said average signal, and said error signal, and responsive thereto for providing a respective drive signal for each of said power switches, wherein said error signal and said average signal have complementary effects on a duty factor of said drive signals and said channel signal has an effect contrary to said error signal and said average signal.

2. The system of claim 1, wherein an increase in one of said error signal and said average signal tends to increase the duty factor of said drive signals while an increase in said channel signal tends to decrease the duty factor.

3. The system of claim 1, wherein said first circuitry includes a phase coupled with at least one of said resistive elements for removing said one resistive element from said node responsive to an indication of a channel having substantial zero load current associated therewith.

4. The system of claim 1, wherein a plurality of said plurality of resistive elements are combined into one component.

5. A multi-phased power system for driving a load, comprising:

a pulse width modulation system having a plurality of phases, each phase including a power switch for selectively coupling a corresponding inductor between a source and said load, said pulse width modulation system further comprising;

a sensor coupled with each phase for sensing a respective channel current and providing a plurality of signals each representative of a corresponding channel current; and

first circuitry coupled with said sensor for receiving said channel current signals and responsive thereto for providing an average signal by summing said channel current signals at a node coupled with a plurality of resistive elements corresponding to the number of phases of said second pulse width modulation system, wherein said average signal is detectable in one of said resistive elements, each resistive element having substantially the same resistivity;

second circuitry coupled with said load and a reference potential and responsive thereto for providing an error signal representative of a difference between said load and said reference potential; and

third circuitry coupled with said sensor, said first circuitry, and said second circuitry for receiving said channel current signals, said average signal, and said error signal, and responsive thereto for providing a drive signal for each of said power switches, wherein said error signal and said average signal have complementary effects on a duty factor of said drive signals and said channel current signal has an effect contrary to said error signal and said average signal.

6. The system of claim 5 further including a further pulse width modulation system, wherein said respective nodes are electrically coupled.

7. A multi-phase power system comprised from a plurality of power converter channels each of which is receptive to the input voltage and the control signals and produces an output voltage and the output current by generating a switching signal depending upon said input voltage and said control signals, allowing the said channel output voltages and the output currents to be coupled together to create a common output rail that is in turn connected to the load, said system comprising:

a control circuit that produces signals for operating the said power system and each power converter channel and is receptive to at least the reference voltage, the output voltage, and the plurality of channel currents flowing though the system, comprising;

means to generate an error signal representative to the difference between the system output voltage and the reference voltage;

means to generate a plurality of the first current signals represent to the power system channel-currents;

means to generate a plurality of the second current signals effectively representative to an average of all channel-currents in the system;

means to combine the said error signal, the said first current signal, and said second current signal into a single control signal individually for each channel from said plurality of power system channels in a way that the error signal action and the second current feedback component action complement each other while the first current feedback component action opposes the action of the error signal and the second current component on a channel duty factor;

means to adjust the contribution of said error signal, said first current signal and said second current signal into said control signal;

means to generate the switching signal based on the said control signal individually for each power system channel.

8. A multi-phase power system as of claim 7 wherein the contribution of said error signal, said first current signal and said second current signal into said control signal allows the double-pole response of the output LC-filter to be substantially suppressed.

9. A multi-phase power system as of claim 8 wherein the first current component is dominating over the second current component such that

{V_contrl=V_err−

(K+X)*i₁+K*(i₁+i₂+i₃ . . . +i_N)/N, where K>

0;

X>

0}.

10. A multi-phase power system as of claim 7 wherein means to generate a plurality of the second current signals effectively representative to an average of all channel-currents in a system is further comprises:

a current share bus that sums into a single node all the first current signals;

a plurality of resistors, one for each channel, that terminates the current share bus;

means to generate a plurality of second current signals from a current branched into at least one of the said resistors.

11. A multi-phase power system as of claim 10 having a current share bus connected to current-share terminal electrically accessible to other members of the multi-module multi-phase power system.

12. A multi-phase power system as of claim 10 wherein individual phases have equal load capability and all resistors connected to the current share bus are of the same value.

13. A multi-phase power system as of claim 10 wherein individual phases have different load capability and values of the resistors connected to the current share is inversely proportional to the current capability of the individual channel.

14. A multi-module power system as of claim 7 further comprised of other multi-phase power systems having the current-share bus terminals all connected together.

15. A multi-module power system as of claim 14 wherein individual modules have equal load capacity and the same impedance of the current-share bus terminals.

16. A multi-module power system as of claim 14 wherein individual modules have different load capability and the impedance of the current-share bus terminals is inversely proportional to the current capability of the individual module.

17. A multi-module power system as of claim 14 wherein individual modules have different load capability having additional means to adjust individual module current share-bus terminal impedance to achieve proper loading of said modules.

18. A multi-phase power system comprised from a plurality of power converter channels each of which is receptive to the input voltage and the control signals and produces an output voltage and the output current by generating a switching signal depending upon said input voltage and said control signals, allowing the channel output voltages and the output currents to be coupled together to create a common output rail that is in turn connected to the load, the system comprising:

a control circuit that produces signals required to operated the said power system and each power converter channel and is receptive to at least the reference voltage the output voltage, and the plurality of channel currents flowing through the system, comprising;

means to generate a plurality of the first current signals representative to the power system channel-currents;

means to generate a plurality of the second current signals effectively representative to a difference between a single channel-current and an average of all channel-currents in the system;

means to combine the said error signal, the said first current signal, and said second current signal into a single control signal individually for each channel form said plurality of power system channels in a way that the first current feedback component action and the second current signal action complement each other and oppose the error signal action on a channel duty factor;

means to adjust the contribution of said error signal, said first current signal and said second current signal into said control signal;

means to generate the switching signal based on the said control signal individually for each power system channel.

19. A multi-phase power system as of claim 18 wherein the contribution of said error signal, said first current signal and said second current signal into said control signal allows the double-pole response of the output LC-filter to be substantially suppressed.

20. A multi-phase power system as of claim 19 wherein the first current component has a non zero contribution into resulting phase control signal;

{V_contrl=Verr−

Xi₁−

K{[(N−

1)/N]*i₁+(i₂+i₃+ . . . +i_N)/N}, where K>

0;

X>

0}.

21. A multi-phase power system as of claim 18 wherein means to generate a current signal effectively representative to an average of all channel-currents in a system is further comprises:

a current share bus that sums into a single node all the first current signals;

a plurality of the resistors, one for each channel, that terminates the current share bus;

means to generate an error signal representative to the difference between the system output voltage and the reference voltage;

means to generate a plurality of signals representative of an average of all channel-currents in the system from a current branched into at least one of the said resistors.

22. A multi-phase power system as of claim 21, wherein a plurality of said plurality of resistive elements are combined into one component.

23. A multi-phase power system as of claim 21 having a current share bus connected to current-share terminal electrically accessible to other members of the multi-module multi-phase power system.

24. A multi-phase power system as of claim 21 wherein individual phases have equal load capacity and all resistors connected to the current share bus are of the same value.

25. A multi-phase power system as of claim 21 wherein individual phases have different load capability and values of the resistors connected to the current share is inversely proportional to the current capability of the individual channel.

26. A multi-module power system as of claim 18 further comprised of other multi-phase power systems having the current-share bus terminals all connected together.

27. A multi-module power system as of claim 26 wherein individual modules have equal load capability and the same impedance of the current-share bus terminals.

28. A multi-module power system as of claim 26 wherein individual modules have different load capacity and the impedance of the current share-bus terminals is inversely proportional to the current capability of the individual module.

29. A multi-module power system as of claim 26 wherein individual modules have different load capacity having additional means to adjust the individual module current share-bus terminal impedance to achieve proper loading of said modules.