Power Converter Employing a Variable Switching Frequency and a Magnetic Device with a Non-Uniform Gap

• US 20100321958A1
• Filed: 06/17/2009
• Published: 12/23/2010
• Est. Priority Date: 06/17/2009
• Status: Active Grant

• Current Assignee: MyPAQ Holdings Ltd. (Transpacific IP Group Limited)
• Original Assignee: Power Systems Technologies Company Limited (Flex, Ltd.)
• Inventors: Garrity, Paul, Silva, Arturo, Jungreis, Aaron, Brinlee, Antony
• Granted Patent: US 8,514,593 B2
• Time in Patent Office: Days
• US Class Current: 363/21.1
• CPC Class Codes: H01F 3/14 Constrictions; Gaps, e.g. air-gaps in magnetic shunt paths H01F3/12
• CPC Class Codes: H02M 3/28 using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac

Abstract

A power converter including a power switch, a controller for controlling a switching frequency thereof, and a magnetic device with a non-uniform gap. In one embodiment, the power converter includes a power switch and a magnetic device coupled to the power switch and having a non-uniform gap. The power converter also includes a controller having a detector configured to sense a condition representing an output power of the power converter. A control circuit of the controller is configured to control a switching frequency of the power switch as a function of the condition and control a duty cycle of the power switch to regulate an output characteristic of the power converter.

Claims

1. A power converter, comprising:

a power switch;

a magnetic device coupled to said power switch and having a non-uniform gap; and

a controller, including;

a detector configured to sense a condition representing an output power of said power converter; and

a control circuit configured to control a switching frequency of said power switch as a function of said condition and control a duty cycle of said power switch to regulate an output characteristic of said power converter.

2. The power converter as recited in claim 1 wherein said control circuit is configured to reduce said switching frequency in accordance with a reduction of said output power.

3. The power converter as recited in claim 1 wherein said magnetic device comprises first and second core sections, said second core section having a leg that forms a gap with said first core section and an end of said leg has a reduced cross-sectional area to form said non-uniform gap.

4. The power converter as recited in claim 1 wherein said magnetic device comprises first and second core sections, said second core section having a leg that forms a gap with said first core section and an end of said leg has a hole bored therein to form said non-uniform gap.

5. The power converter as recited in claim 1 wherein said magnetic device comprises first and second core sections, said second core section having a leg that forms a gap with said first core section and a core piecepart positioned at an end of said leg to form said non-uniform gap.

6. The power converter as recited in claim 1 wherein said magnetic device comprises first and second core sections, said second core section having a leg with a tapered region at an end thereof to form said non-uniform gap with said first core section for said magnetic device.

7. The power converter as recited in claim 1 wherein said magnetic device, comprises:

a first magnetic core having first and second core sections, said second core section of said first magnetic core having a leg that forms a first gap with said first core section of said first magnetic core, and

a second magnetic core adjacent said first magnetic core and having first and second core sections, said second core section of said second magnetic core having a leg that forms a second gap with said first core section of said second magnetic core, said first and second gaps forming said non-uniform gap.

8. The power converter as recited in claim 1 wherein said detector comprises a resistor, a capacitor and a diode

9. The power converter as recited in claim 1 wherein said control circuit comprises a frequency control circuit configured to control said switching frequency of said power switch and a pulse-width modulator configured to control said duty cycle of said power switch.

10. The power converter as recited in claim 1 wherein said control circuit comprises a timing capacitor, a timing resistor, an amplifier, a current mirror, and a pulse-width modulator.

11. The power converter as recited in claim 1 wherein said condition representing said output power of said power converter comprises at least one of a current associated with said power switch and an output current of said power converter.

12. The power converter as recited in claim 1 wherein said control circuit is configured to provide a continuous change of said switching frequency as a function of a change of said condition.

13. The power converter as recited in claim 1 wherein said control circuit is configured to provide a lower limit of said switching frequency for said power switch.

14. The power converter as recited in claim 1 wherein said control circuit is configured to control said switching frequency of said power switch during a non burst mode of operation of said power converter.

15. The power converter as recited in claim 1 wherein said condition representing said output power of said power converter is provided in accordance with a selected input voltage of said power converter.

16. A method of operating a power converter, comprising:

providing a power switch;

coupling a magnetic device having a non-uniform gap to said power switch;

sensing a condition representing an output power of said power converter;

controlling a switching frequency of said power switch as a function of said condition; and

controlling a duty cycle of said power switch to regulate an output characteristic of said power converter.

17. The method as recited in claim 16 wherein said controlling said switching frequency of said power switch comprises reducing said switching frequency in accordance with a reduction of said output power.

18. The method as recited in claim 16 wherein said controlling said switching frequency of said power switch comprises providing a continuous change of said switching frequency as a function of a change of said condition.

19. The method as recited in claim 16 wherein said controlling said switching frequency of said power switch comprises providing a lower limit of said switching frequency for said power switch.

20. The method as recited in claim 16 wherein said condition representing said output power of said power converter is provided in accordance with a selected input voltage of said power converter.