Method, apparatus and system for extended switched-mode controller

• US 8,319,486 B2
• Filed: 06/13/2008
• Issued: 11/27/2012
• Est. Priority Date: 06/13/2008
• Status: Active Grant

• Current Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Original Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Inventors: Maksimovic, Dragan, Yousefzadeh, Vahid, Alarcon, Eduard
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): LEE III, HENRY E
• Application Number:
  US12/139,340
• Publication Number:
  US 20090310385A1
• Time in Patent Office: 1,628 Days
• Field of Search: 323/222, 323/224, 323/282, 323/283, 323/284
• US Class Current: 323/283
• 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 3/157 with digital control

Abstract

An exemplary extended switched-mode controller is provided for controlling the switching of a switched-mode power converter. This exemplary extended switched-mode controller further comprises a standard switched-mode controller and an auxiliary controller configured to receive standard switch control signals from the switched-mode controller and to (1) pass the standard switch control signals to the switched-mode power converter during non-transient operation, and (2) provide auxiliary switch control signals to the switched-mode power converter during transient operation instead of the standard switch control signals. The auxiliary controller is further configured to determine when to provide the auxiliary switch control signals and to determine what control signals to provide at least partially based on an auxiliary feedback input signal comprising at least one of: sensed converter voltages, converter currents, and an error signal. Where the error signal is at least partially based on the difference between a feedback signal and a reference signal.

Claims

1. An extended switched-mode controller for controlling the switching of a switched-mode power converter during both non-transient and transient events, wherein the switched-mode power converter comprises at least one switch and at least one filter, and wherein the at least one filter comprises an inductor and an output capacitor, the extended switched-mode controller comprising:

a comparator configured to receive a feedback signal from the output of the switched-mode power converter and to receive a reference signal;

wherein said comparator is further configured to generate an error signal based at least in part on the difference between said feedback signal and said reference signal;

a switched-mode controller configured to determine and generate standard switch control signals for the switched-mode power converter based at least in part on said error signal; and

an auxiliary controller configured to receive said standard switch control signals from said switched-mode controller and to (1) pass said standard switch control signals to the switched-mode power converter during non-transient operation, and (2) provide auxiliary switch control signals to the switched-mode power converter during transient operation instead of said standard switch control signals;

wherein said auxiliary controller is further configured to determine when to provide said auxiliary switch control signals and to determine what control signals to provide based at least in part on an auxiliary feedback input signal comprising at least one of;

sensed converter voltages, converter currents, and said error signal; and

wherein said auxiliary controller is a switching surface controller.

2. The extended switched-mode controller of claim 1, wherein said auxiliary feedback input signal is sampled by an analog-to-digital converter and said auxiliary controller is configured to operate digitally.

3. The extended switched-mode controller of claim 2, wherein said comparator is an analog-to-digital converter and said switched-mode controller is configured to operate digitally.

4. The extended switched-mode controller of claim 3, wherein said auxiliary controller is implemented as a state machine and said switched-mode controller is a constant-frequency digital pulse-width modulation (“

PWM”

) controller.

5. The extended switched-mode controller of claim 1, wherein said feedback signal is representative of an output voltage at an output of the switched-mode power converter, wherein said reference signal is a reference voltage, and wherein said error signal is representative of the difference between said output voltage and said reference voltage.

6. The extended switched-mode controller of claim 1, wherein said switched-mode controller comprises at least one of:

a current-mode controller, hysteretic controller, sliding-mode controller, a controller based on pulse-frequency modulation, and a controller utilizing a combination of these techniques.

7. The extended switched-mode controller of claim 4, wherein said switching surface controller comprises a switching surface that depends at least in part on said error signal and a capacitor current in said switched-mode power converter.

8. The extended switched-mode controller of claim 4, wherein said switching surface controller comprises a switching surface that depends at least in part on said error signal and output of a hybrid capacitor current estimator of a capacitor current in said switched-mode power converter.

9. The extended switched-mode controller of claim 8, wherein said hybrid capacitor current estimator comprises an input equal to said error signal, and at least one of:

a finite difference filter, a moving average filter, and an integral estimator based on slopes of an inductor current in said switched-mode power converter.

10. The extended switched-mode controller of claim 8, wherein said hybrid capacitor current estimator comprises an input equal to said error signal, a finite difference filter, a moving average filter, and an integral estimator based on slopes of an inductor current in said switched-mode power converter.

11. The extended switched-mode controller of claim 1, wherein said switching surface controller is a nonlinear switching surface controller.

12. The extended switched-mode controller of claim 4, wherein said switching surface controller is a nonlinear switching surface controller.

13. An auxiliary controller for association with a standard switched-mode controller for controlling the switching of a switched-mode power converter during both non-transient and transient events, wherein the switched-mode power converter comprises at least one switch and at least one filter, and wherein the at least one filter comprises an inductor and an output capacitor, the auxiliary controller comprising:

a standard control signal input configured to receive standard switch controls signals from the standard switched-mode controller;

an auxiliary feedback input configured to receive an auxiliary feedback input signal comprising at least one of;

sensed converter voltages, converter currents, and an error signal; and

a switch control signal output configured to provide switch control signals to the switched-mode power converter, wherein said auxiliary controller is configured to receive said standard switch control signals from the standard switched-mode controller and based upon said auxiliary feedback input signal to (1) pass said standard switch control signals to the switched-mode power converter during non-transient mode operation, and (2) provide auxiliary switch control signals to the switched-mode power converter during transient mode operation instead of said standard switch control signals;

wherein said auxiliary controller is further configured, to determine when to provide said auxiliary switch control signals and to determine what control signals to provide based at least in part on said auxiliary feedback input signal, and wherein said auxiliary controller is a switching surface controller.

14. The auxiliary controller of claim 13, wherein said auxiliary feedback input signal is based upon the difference between a reference voltage and an output voltage at an output of the switched-mode power converter.

15. The auxiliary controller of claim 13, wherein said auxiliary feedback signal is sampled by an analog-to-digital converter and said auxiliary controller is configured to operate digitally.

16. The auxiliary controller of claim 15, wherein said auxiliary controller is a state machine and said standard switched-mode controller is a constant-frequency digital pulse-width modulation (“

PWM”

) controller.

17. The auxiliary controller of claim 16, wherein said switching surface controller comprises a switching surface that depends at least in part on said error signal and a capacitor current in said standard switched-mode power converter.

18. The auxiliary controller of claim 16, wherein said switching surface controller comprises a switching surface that depends at least in part on said error signal and output of a hybrid capacitor current estimator of a capacitor current in said standard switched-mode power converter.

19. The auxiliary controller of claim 18, wherein said hybrid capacitor current estimator comprises an input equal to said error signal, and at least one of:

a finite difference filter, a moving average filter, an integral estimator based on slopes of an inductor current in said standard switched-mode power converter.

20. The auxiliary controller of claim 19, wherein said hybrid capacitor current estimator comprises an input equal to said error signal, a finite difference filter, a moving average filter, and an integral estimator based on slopes of an inductor current in said switched-mode power converter.

21. The auxiliary controller of claim 13, wherein said switching surface controller is a nonlinear switching surface controller.

22. The auxiliary controller of claim 16, wherein said switching surface controller is a nonlinear switching surface controller.

23. A switched-mode power converter system for controlling the switching of a switched-mode power converter during both non-transient and transient events, the switched-mode power converter system comprising:

a switched-mode power converter comprising a first switch and a second switch and a converter output, wherein said output is configured to provide power to a load, wherein said switched-mode power converter comprises and at least one filter, and wherein said at least one filter comprises an inductor and an output capacitor;

a comparator configured to receive a feedback signal from said converter output of said switched-mode power converter and to receive a reference signal;

wherein said comparator is further configured to generate an error signal based at least in part on the difference between said feedback signal and said reference signal;

a switched-mode controller configured to determine and generate standard switch control signals for the switched-mode power converter; and

an auxiliary controller configured to receive said standard switch control signals from said switched-mode controller and to (1) pass said standard switch control signals to the switched-mode power converter during non-transient operation, and (2) provide auxiliary switch control signals to the switched-mode power converter during transient operation instead of said standard switch control signals;

wherein said auxiliary controller is further configured to determine when to provide said auxiliary switch control signals and to determine what control signals to provide based at least in part on an auxiliary feedback input signal comprising at least one of;

sensed converter voltages, converter currents, and said error signal; and

wherein said auxiliary controller is a switching surface controller implemented as a state machine and employs capacitor current estimation.

24. The switched-mode power converter system of claim 23, wherein said feedback signal is representative of an output voltage at an output of the switched-mode power converter, wherein said reference signal is a reference voltage, and wherein said error signal is representative of the difference between said output voltage and said reference voltage.

25. The switched-mode power converter system of claim 23, wherein said switched-mode controller is a constant-frequency pulse-width modulation (“

PWM”

) controller, and wherein said switched-mode controller comprises at least one of;

a current-mode controller, hysteretic controller, sliding-mode controller, a controller based on pulse-frequency modulation, and a controller utilizing a combination of these techniques.

26. The switched-mode power converter system of claim 23, wherein said comparator is an analog-to-digital converter, said switched-mode controller is a constant-frequency digital pulse-width modulation (DPWM) controller, said auxiliary feedback input signal is said error signal.

27. A method for regulating voltage to a variable load, the method comprising the steps of:

providing standard control signals to the switched-mode power converter during non-transient operation of the switched-mode power converter, wherein the standard control signals are based on feedback from the output of the switched-mode power converter, and wherein said standard control signals are derived based on at least one of the following types of controllers;

constant-frequency pulse-width modulation (PWM) controller, current-mode controller, hysteretic controller, sliding-mode controller, a controller based on pulse-frequency modulation, and a controller utilizing a combination of these techniques; and

overriding the standard control signals with auxiliary control signals during a transient event, wherein the determination of when to perform said overriding and wherein the determination of the values of said auxiliary control signals are based at least in part on an auxiliary feedback input signal comprising at least one of;

sensed converter voltages, converter currents, and said error signal; and

wherein the determination of when to perform said overriding is based upon evaluating whether a switching surface has been crossed.

28. A method for regulating voltage to a variable load, the method comprising the steps of:

evaluating whether a transient condition threshold has been reached and until said transient condition threshold has been reached continuing to pass control signals from a standard switched-mode controller to a switched-mode power converter, wherein said switched-mode power converter comprises at least one switch and at least one filter, and wherein the at least one filter comprises an inductor and an output capacitor;

upon determining that said transient condition threshold has been reached, evaluating whether a switching surface has been crossed and determining auxiliary control signals, wherein evaluating whether a switching surface has been crossed is performed using capacitor current estimation techniques, wherein said auxiliary control signals are determined to be one of c=1 and c=0, and wherein said determining of said auxiliary control signals is based on whether said transient condition threshold that was crossed was an upper or lower threshold;

replacing said control signals from said standard switched-mode controller with said determined auxiliary control signals and providing said auxiliary control signals to said at least one switch in said switched-mode power converter;

evaluating whether a non-transient condition threshold has been reached and (1) if the non-transient threshold has not been reached, repeating the steps of evaluating whether a switching surface has been crossed, determining auxiliary control signals, replacing said control signals from said standard switched-mode controller with said determined auxiliary control signals, and providing said auxiliary control signals to said at least one switch in said switched-mode power converter; and

(2) if the non-transient threshold has been reached, reverting to passing said control signals from said standard switched-mode controller on to said switched-mode power converter.