Optimal feedback control of switch-mode power converters

• US 7,459,893 B2
• Filed: 04/13/2007
• Issued: 12/02/2008
• Est. Priority Date: 04/20/2006
• Status: Expired due to Fees

• Current Assignee: Mark E. Jacobs
• Original Assignee: Mark E. Jacobs
• Inventors: Jacobs, Mark E
• Primary Examiner(s): Laxton; Gary L
• Application Number:
  US11/735,274
• Publication Number:
  US 20070247129A1
• Time in Patent Office: 599 Days
• Field of Search: 323/222, 323/223, 323/224, 323/265, 323/282, 323/283, 323/284, 323/351
• US Class Current: 323/282
• CPC Class Codes: H02M 3/157 with digital control
• CPC Class Codes: H02M 3/33515 with digital control

Abstract

A power converter including a power switch, an output filter, and a controller. The output filter receives a switched input voltage and produces a filtered power converter output characteristic represented by a state vector. A controller coupled to the power switch and the output filter estimates the state vector of the output filter and controls the power switch by partitioning a state-vector plane into a first region and a second region employing a line passing through a desired output characteristic. The controller turns the power switch on when the estimated state vector lies in the first region and off when it lies in the second region. The steady-state switching frequency of the power converter is controlled by offsetting a state-vector component at a desired switching frequency. To estimate the state vector of the output filter, the controller may advantageously be coupled to the switched input voltage.

Claims

1. A power converter, comprising:

a power switch;

an output filter coupled to said power switch to receive a switched input voltage and produce an output characteristic of said power converter; and

a controller coupled to said power switch and to said output filter, wherein said controller estimates a state vector of said output filter comprising at least two state-vector components and controls said output characteristic with a nonlinear partition of a state-vector plane, said partition separating said state-vector plane into a first region and a second region, wherein said controller turns said power switch on when said state vector lies in said first region and off when said state vector lies in said second region.

2. The power converter as recited in claim 1 wherein said partition passes through a point representing a desired output characteristic of said power converter.

3. The power converter as recited in claim 1 wherein said partition is formed with ellipses.

4. The power converter as recited in claim 1 wherein said partition includes a component of said state vector offset with a waveform having a desired switching frequency of said power converter.

5. The power converter as recited in claim 1 wherein said partition is sensed with a process including hysteresis.

6. The power converter as recited in claim 1, wherein said controller is further coupled to said switched input voltage.

7. The power converter as recited in claim 1 wherein said controller produces a modeled state-vector response of said output filter to said switched input voltage.

8. The power converter as recited in claim 7 wherein said controller employs a difference between said modeled state-vector response and a sensed characteristic of said output filter to correct said modeled response.

9. The power converter as recited in claim 1 wherein said controller senses a current in an output capacitor to estimate a component of said state vector.

10. A method of controlling a power converter including a power switch, comprising:

coupling an output filter to said power switch to receive a switched input voltage and produce an output characteristic of said power converter;

coupling a controller to said power switch and to said output filter and estimating in said controller a state vector comprising at least two state-vector components of said output filter;

separating a state-vector plane into a first region and a second region with a nonlinear partition of said state-vector plane; and

controlling said output characteristic by turning on said power switch when said state vector lies in said first region and off said power switch when said state vector lies in said second region.

11. The method as recited in claim 10 including forming said partition so that it passes through a point representing a desired output characteristic of said power converter.

12. The method as recited in claim 10 including forming said partition with ellipses.

13. The method as recited in claim 10 including forming said partition with nonlinear functions.

14. The method as recited in claim 10 including forming said partition with a time-delayed component of said state vector.

15. The method as recited in claim 10 including forming said partition with a component of said state vector offset at a desired switching frequency of said power converter.

16. The method as recited in claim 10 further including coupling said controller to said switched input voltage.

17. The method as recited in claim 10 including producing in said controller a modeled state-vector response of said output filter to said switched input voltage.

18. The method as recited in claim 17 including employing in said controller a difference between said modeled state-vector response and a sensed characteristic of said output filter to correct said modeled response.