MULTIPHASE DIGITAL CURRENT MODE CONTROLLER WITH DYNAMIC CURRENT ALLOCATION

• US 20140015500A1
• Filed: 07/12/2012
• Published: 01/16/2014
• Est. Priority Date: 07/12/2012
• Status: Active Grant

• Current Assignee: Infineon Technologies Austria Ag (Infineon Technologies AG)
• Original Assignee: Primarion Incorporated (Infineon Technologies AG)
• Inventors: Babazadeh, Amir, Tang, Benjamim, Bernacchia, Giuseppe, Ostrom, Kenneth
• Granted Patent: US 9,240,721 B2
• Time in Patent Office: Days
• US Class Current: 323/272
• CPC Class Codes: H02M 1/0032 Control circuits allowing low power mode operation, e.g. in standby mode
• CPC Class Codes: H02M 3/1566 with means for compensating against rapid load changes, e.g. with auxiliary current source, with dual mode control or with inductance variation
• CPC Class Codes: H02M 3/1584 with a plurality of power processing stages connected in parallel
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A multiphase switching regulator includes a power stage with at least a first phase and a second phase for supplying power to a load through inductors coupling the phases to the load. The multiphase switching regulator is operated by switching the first phase at a higher switching frequency than the second phase via pulse width modulation (PWM) signals provided to the phases. A phase-specific target current is generated for each phase at the switching frequency for that phase based on the difference between an output voltage of the power stage and a reference voltage. The current in the inductors coupling the phases to the load is sensed, and a duty cycle of the PWM signal provided to each phase is adjusted based on the phase-specific target current and sensed inductor current for that phase.

Claims

1. A method of operating a multiphase switching regulator having a power stage with at least a first phase and a second phase for supplying power to a load through inductors coupling the phases to the load, the method comprising:

switching the first phase at a higher switching frequency than the second phase via pulse width modulation (PWM) signals provided to the phases;

generating a phase-specific target current for each phase at the switching frequency for that phase based on the difference between an output voltage of the power stage and a reference voltage;

sensing the current in the inductors coupling the phases to the load; and

adjusting a duty cycle of the PWM signal provided to each phase based on the phase-specific target current and sensed inductor current for that phase.

2. The method according to claim 1, wherein adjusting the duty cycle of the PWM signals comprises:

generating a current error signal for each phase based on the difference between the phase-specific target current and sensed inductor current for that phase; and

adjusting the duty cycle of the PWM signal provided to each phase based on the current error signal for that phase.

3. The method according to claim 2, further comprising removing high frequency components of the current error signals.

4. The method according to claim 2, further comprising scaling the current error signals.

5. The method according to claim 2, wherein the phase-specific target current is the peak current for a next cycle of the PWM signal or the average current for the next cycle.

6. The method according to claim 1, further comprising switching both the first and second phases to respond to a fast dynamic condition.

7. The method according to claim 1, further comprising dynamically adjusting the amount of current carried by one or more of the phases.

8. The method according to claim 7, wherein dynamically adjusting the amount of current carried by each phase comprises deactivating one or more of the phases and redistributing the current to each remaining active phase responsive to a decrease in the load current.

9. The method according to claim 7, wherein dynamically adjusting the amount of current carried by each phase comprises activating one or more previously deactivated ones of the phases and redistributing the current to each active phase responsive to an increase in the load current.

10. The method according to claim 1, further comprising allocating the load current unequally between the phases.

11. The method according to claim 1, further comprising scaling the phase-specific target currents.

12. The method according to claim 1, further comprising increasing the current provided by the first phase to the load responsive to a dynamic transition in the output voltage before the phase-specific target current for the first phase reflects the dynamic transition in the output voltage.

13. The method according to claim 12, wherein increasing the current provided by the first phase to the load responsive to the dynamic transition in the output voltage comprises combining a pulse signal with the phase-specific target current and sensed inductor current for the first phase before the phase-specific target current for the first phase reflects the dynamic transition in the output voltage.

14. The method according to claim 12, wherein increasing the current provided by the first phase to the load responsive to the dynamic transition in the output voltage comprises combining a scaled derivative of the output voltage with the phase-specific target current and sensed inductor current for the first phase before the phase-specific target current for the first phase reflects the dynamic transition in the output voltage.

15. The method according to claim 1, further comprising limiting a maximum current supplied to the load.

16. A multiphase switching regulator, comprising:

a power stage including at least a first phase and a second phase for supplying power to a load through inductors coupling the phases to the load;

current sensors operable to sense the current in the inductors coupling the phases to the load; and

a controller operable to switch the first phase at a higher switching frequency than the second phase via pulse width modulation (PWM) signals provided to the phases, generate a phase-specific target current for each phase at the switching frequency for that phase based on the difference between an output voltage of the power stage and a reference voltage, and adjust a duty cycle of the PWM signal provided to each phase based on the phase-specific target current and sensed inductor current for that phase.

17. The multiphase switching regulator according to claim 16, wherein the controller is operable to generate a current error signal for each phase based on the difference between the phase-specific target current and sensed inductor current for that phase, and to adjust the duty cycle of the PWM signal provided to each phase based on the current error signal for that phase.

18. The multiphase switching regulator according to claim 17, wherein the controller is operable to remove high frequency components of the current error signals.

19. The multiphase switching regulator according to claim 17, wherein the controller is operable to scale the current error signals.

20. The multiphase switching regulator according to claim 17, wherein the phase-specific target current is the peak current for a next cycle of the PWM signal or the average current for the next cycle.

21. The multiphase switching regulator according to claim 16, wherein the controller is operable to switch both the first and second phases to respond to a fast dynamic condition.

22. The multiphase switching regulator according to claim 16, wherein the controller is operable to dynamically adjust the amount of current carried by one or more of the phases.

23. The multiphase switching regulator according to claim 22, wherein the controller is operable to deactivate one or more of the phases and redistribute the current to each remaining active phase responsive to a decrease in the load current.

24. The multiphase switching regulator according to claim 22, wherein the controller is operable to activate one or more previously deactivated ones of the phases and redistribute the current to each active phase responsive to an increase in the load current.

25. The multiphase switching regulator according to claim 16, wherein the controller is operable to allocate the load current unequally between the phases.

26. The multiphase switching regulator according to claim 16, wherein the controller is operable to scale the phase-specific target currents.

27. The multiphase switching regulator according to claim 16, wherein the controller is operable to increase the current provided by the first phase to the load responsive to a dynamic transition in the output voltage before the phase-specific target current for the first phase reflects the dynamic transition in the output voltage.

28. The multiphase switching regulator according to claim 27, wherein the controller is operable to combine a pulse signal with the phase-specific target current and sensed inductor current for the first phase before the phase-specific target current for the first phase reflects the dynamic transition in the output voltage.

29. The multiphase switching regulator according to claim 27, wherein the controller is operable to combine a scaled derivative of the output voltage with the phase-specific target current and sensed inductor current for the first phase before the phase-specific target current for the first phase reflects the dynamic transition in the output voltage.

30. The multiphase switching regulator according to claim 16, wherein the controller comprises a nonlinear proportional-integral-derivative (PID) controller including a first integral unit associated with the first and second phases and which is active for steady state load conditions, a second integral unit associated with the first and second phases and which is active for fast dynamic conditions, a first proportional unit associated with the first phase, a second proportional unit associated with the second phase, a first derivative unit associated with the first phase, and second derivative unit associated with the second phase, and wherein the nonlinear PID controller is operable to generate the phase-specific target current for each phase based on the difference between the output voltage and the reference voltage, the difference input as an error signal to the first and second integral units, the first and second proportional units and the first and second derivative units.

31. The multiphase switching regulator according to claim 30, wherein the nonlinear PID controller further includes one or more filters operable to filter the error signal so that the error signal is non-zero only during fast dynamic conditions when input to the second integral unit and the first derivative unit.

32. The multiphase switching regulator according to claim 16, wherein the controller comprises a plurality of compensators, each compensator operable to generate the phase-specific target current for one of the phases.

33. The multiphase switching regulator according to claim 16, wherein the controller is operable to limit a maximum current supplied to the load.