Controller for Use with a Power Converter and Method of Operating the Same

• US 20140091720A1
• Filed: 09/28/2012
• Published: 04/03/2014
• Est. Priority Date: 09/28/2012
• Status: Abandoned Application

• Current Assignee: Power Systems Technologies Company Limited (Flex, Ltd.)
• Original Assignee: Power Systems Technologies Company Limited (Flex, Ltd.)
• Inventors: Brinlee, Antony
• Application Number:
  US13/631,482
• Publication Number:
  US 20140091720A1
• Time in Patent Office: Days
• US Class Current: 315/186
• CPC Class Codes: H02M 1/007 Plural converter units in cascade push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826
• CPC Class Codes: H02M 1/4225 using a non-isolated boost converter
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: H05B 45/382 with galvanic isolation between input and output
• CPC Class Codes: H05B 45/39 Circuits containing inverter bridges
• 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 controller for use with a power converter and method of operating the same. In one embodiment, the controller includes a light emitting diode string controller configured to receive a dimmer signal and control a level of current in a light emitting diode string in response to the dimmer signal. The controller also includes a power converter controller configured to receive the dimmer signal and control an output current of the power converter that is a multiple of the level of current in the light emitting diode string.

Claims

1. A controller for use with a power converter, comprising:

a light emitting diode string controller configured to receive a dimmer signal and control a level of current in a light emitting diode string in response to said dimmer signal; and

a power converter controller configured to receive said dimmer signal and control an output current of said power converter that is a multiple of said level of current in said light emitting diode string.

2. The controller as recited in claim 1 further comprising another light emitting diode controller configured to receive said dimmer signal and control a level of current in another light emitting diode string in response to said dimmer signal.

3. The controller as recited in claim 1 wherein said power converter controller comprises:

a differential amplifier configured to sense an output current of said power converter to provide a sensed output current; and

an error amplifier configured to provide an error signal as a function of said sensed output current and said dimmer signal to control said output current of said power converter.

4. The controller as recited in claim 1 wherein said power converter controller comprises:

a differential amplifier configured to sense an output current of said power converter to provide a sensed output current;

a resistor divider configured to sense an output voltage of said power converter to provide a sensed output voltage; and

an error amplifier configured to provide an error signal as a function of said sensed output current, said sensed output voltage and said dimmer signal to control said output current of said power converter.

5. The controller as recited in claim 4 wherein said error amplifier is configured to decrease said output current of said power converter in response to an increase in said sensed output voltage.

6. The controller as recited in claim 1 wherein said power converter controller comprises:

an inductor-inductor-capacitor (LLC) controller configured to receive an error signal representative of said output current of said power converter to control a switching frequency of an LLC stage of said power converter; and

a power factor correction (PFC) controller configured to control a bus voltage produced by a PFC stage of said power converter and provided to said LLC stage so that an average switching frequency of said LLC stage is substantially maintained at a desired switching frequency.

7. The controller as recited in claim 6 wherein said desired switching frequency is substantially equal to a resonant frequency of said LLC stage.

8. The controller as recited in claim 1 wherein said light emitting diode string controller comprises:

a current-sense resistor configured to sense said current in said light emitting diode string to provide a sensed current in said light emitting diode string;

a differential amplifier configured to provide a signal as a function of said sensed current in said light emitting diode string;

an error amplifier configured to provide an error signal as a function of said signal from said differential amplifier and said dimmer signal; and

a linear regulator configured to control said level of current in a light emitting diode string as a function of said error signal.

9. The controller as recited in claim 1 further comprising a burst mode controller configured to cause said power converter to enter a burst mode of operation under a light load.

10. A method for use with a power converter, comprising:

controlling a level of current in a light emitting diode string in response to a dimmer signal; and

controlling an output current of said power converter in response to said dimmer signal that is a multiple of said level of current in said light emitting diode string.

11. The method as recited in claim 10 further comprising controlling a level of current in another light emitting diode string in response to said dimmer signal.

12. The method as recited in claim 10, further comprising:

sensing an output current of said power converter to provide a sensed output current; and

providing an error signal as a function of said sensed output current and said dimmer signal to control said output current of said power converter.

13. The method as recited in claim 10, further comprising:

sensing an output current of said power converter to provide a sensed output current;

sensing an output voltage of said power converter to provide a sensed output voltage; and

providing an error signal as a function of said sensed output current, said sensed output voltage and said dimmer signal to control said output current of said power converter.

14. The method as recited in claim 13 further comprising decreasing said output current of said power converter in response to an increase in said sensed output voltage.

15. The method as recited in claim 10, further comprising:

sensing said current in said light emitting diode string to provide a sensed current in said light emitting diode string;

providing an error signal as a function of said sensed current in said light emitting diode string and said dimmer signal; and

controlling said level of current in a light emitting diode string as a function of said error signal.

16. A power converter, comprising:

a power factor correction (PFC) stage;

an inductor-inductor-capacitor (LLC) stage coupled to said PFC stage; and

a controller, comprising;

a light emitting diode string controller configured to receive a dimmer signal and control a level of current in a light emitting diode string in response to said dimmer signal; and

a power converter controller configured to receive said dimmer signal and control an output current of said power converter that is a multiple of said level of current in said light emitting diode string.

17. The power converter as recited in claim 16 wherein said controller further comprises another light emitting diode controller configured to receive said dimmer signal and control a level of current in another light emitting diode string in response to said dimmer signal.

18. The power converter as recited in claim 16 wherein said power converter controller comprises:

a differential amplifier configured to sense an output current of said power converter to provide a sensed output current; and

an error amplifier configured to provide an error signal as a function of said sensed output current and said dimmer signal to control said output current of said power converter.

19. The power converter as recited in claim 16 wherein said power converter controller comprises:

a differential amplifier configured to sense an output current of said power converter to provide a sensed output current;

a resistor divider configured to sense an output voltage of said power converter to provide a sensed output voltage; and

an error amplifier configured to provide an error signal as a function of said sensed output current, said sensed output voltage and said dimmer signal to control said output current of said power converter.

20. The power converter as recited in claim 16 wherein said light emitting diode string controller comprises:

a current-sense resistor configured to sense said current in said light emitting diode string to provide a sensed output current;

a differential amplifier configured to provide a signal as a function of said sensed current in said light emitting diode string;

an error amplifier configured to provide an error signal as a function of said signal from said differential amplifier and said dimmer signal; and

a linear regulator configured to control said level of current in said light emitting diode string as a function of said error signal.