Frequency modulation for controlling switched resonant converter

Patent metadata

Field	Value
Publication number	US-12348147-B2
Application number	US-202118040123-A
Country	US
Kind code	B2
Filing date	Sep 10, 2021
Priority date	Sep 10, 2020
Publication date	Jul 1, 2025
Grant date	Jul 1, 2025

Abstract

An LED converter for supply of an LED load ( 18 ) is provided. The LED converter comprises a switched resonant converter ( 1 ) having at least one switch ( 11, 12 ) controlled by a control unit of the switched resonant converter ( 1 ). The control unit is configured to control a switching operation of the at least one switch ( 11, 12 ) such that the switched resonant converter ( 1 ) supplies an adjustable constant current ( 17 ) to output terminals for the LED load ( 18 ). The control unit is further configured to generate the adjustable constant current ( 17 ) by alternatingly controlling the at least one switch ( 11, 12 ) with one of at least two different, and adaptable, switching frequencies ( 44, 45 ) at a time for a respective time period ( 54, 55 ), and by adjusting a relative duration of the time periods ( 54, 55 ). Thereby, a resolution of an output current of the LED converter for supply of the LED load ( 18 ) is improved, which is of particular relevance for dimming applications.

First claim

The invention claimed is:

1. An LED converter for supply of an LED load ( 18 ), comprising
a switched resonant converter ( 1 ) having
at least one switch ( 11 , 12 ) controlled by
a control unit of the switched resonant converter ( 1 ),

the control unit being configured to control a switching operation of the at least one switch ( 11 , 12 ) such that the switched resonant converter ( 1 ) supplies an adjustable constant current ( 17 ) to output terminals for the LED load ( 18 ),
the control unit further being configured to generate the adjustable constant current ( 17 ) by alternatingly controlling the at least one switch ( 11 , 12 ) with one of at least two different switching frequencies ( 44 , 45 ) at a time for a respective time period ( 54 , 55 ), and by adjusting a relative duration of the respective time periods ( 54 , 55 ),
wherein the at least two different switching frequencies ( 44 , 45 ) respectively exceed a peak resonance frequency of the converter ( 1 ) and the at least two different switching frequencies ( 44 , 45 ) are adaptable; and
a further control unit ( 100 ) communicating with the control unit ( 19 ) over a bidirectional channel ( 103 , 104 , 17 ′).

2. The LED converter of claim 1 , wherein the further control unit ( 100 ) is connected to a communication interface ( 101 ) of the LED converter that communicates externally over a wireless or wireline channel.

3. The LED converter of claim 1 , wherein the further control unit ( 100 ) is supplied with a signal representing the output current or an LED current.

4. The LED converter of claim 1 , wherein the further control unit ( 100 ) sends a signal ( 103 ) to the control unit ( 1 ) instructing duty cycles of the different switching frequencies used by the control unit ( 19 ) for operating the one or more switches ( 11 ).

5. The LED converter of claim 1 , wherein the different switching frequencies to be used by the control unit ( 19 ) are provided by the further control unit ( 100 ), or wherein the different switching frequencies to be used by the control unit ( 19 ) are determined by the control unit ( 19 ) without instructions from the further control unit ( 100 ).

6. The LED converter of claim 1 , wherein the at least two different switching frequencies ( 44 , 45 ) consists of only two different switching frequencies ( 44 , 45 ).

7. A lighting system, comprising:
an LED converter of claim 1 , and
an LED load ( 18 ) configured to be supplied by an output current of said LED converter.

8. A method ( 70 ) of operating an LED converter for supply of an LED load ( 18 ), the LED converter comprising a switched resonant converter ( 1 ) having
at least one switch ( 11 , 12 ) controlled by
a control unit of the switched resonant converter ( 1 ),
the method ( 70 ) comprising:
controlling ( 71 ) a switching operation of the at least one switch ( 11 , 12 ) according to a duty cycle such that the switched resonant converter ( 1 ) supplies an adjustable constant current ( 17 ) to output terminals for the LED load ( 18 );
generating ( 72 ) the adjustable constant current ( 17 ) by alternatingly controlling the at least one switch ( 11 , 12 ) with one of at least two different switching frequencies ( 44 , 45 ) at a time for a respective time period ( 54 , 55 ) of the duty cycle, and by adjusting a relative duration of the respective time periods ( 54 , 55 ), of the duty cycle;
adapting the at least two different switching frequencies ( 44 , 45 ) during the operation of the LED converter, wherein the at least two different switching frequencies ( 44 , 45 ) respectively exceed a peak resonance frequency of the switched resonant converter ( 1 );
measuring the adjustable constant current and generating a feedback signal representing the measured adjustable constant current;
using the feedback signal to adjust the duty cycle when controlling the switched resonant converter to supply the adjustable constant current to the output terminals for the LED load.

9. The method ( 70 ) of claim 8 , wherein the method ( 70 ) is performed by an LED converter of claim 1 .

10. A control unit for an LED converter, wherein the control unit is designed for implementing the method ( 70 ) of claim 8 .

11. The method of claim 8 wherein the feedback signal is provided to a further control unit that is not part of the switched resonant converter, and said further control unit communicates with the control unit of the switched resonant converter over a bidirectional channel, and further wherein the further control unit sends a signal to the control unit of the switched resonant converter instructing duty cycles of the different switching frequencies used by the control unit of the switched resonant converter to operate the one or more switches of the switched resonant converter.

12. The method of claim 11 wherein the different switching frequencies to be used by the control unit of the switched resonant converter are provided by the further control unit not part of the switched resonant converter.

13. The method of claim 11 wherein the different switching frequencies to be used by the control unit of the switched resonant converter are determined by the control unit of the switched resonant converter without instructions from the further control unit not part of the switched resonant converter.

14. The method of claim 11 wherein the further control unit not part of the switched resonant converter is connected to a communications interface for a lighting system and receives instructions regarding dimming levels from said communications interface, and the signal sent to the control unit of the switched resonant converter instructing duty cycles is based in part on the instructions regarding dimming levels.

Assignees

• Tridonic Gmbh & Co Kg

Inventors

• Maldoner Jakob
• Marte Patrick
• Walch Patrick

Classifications

• H02M3/01

  Resonant DC/DC converters · CPC title

• Y02B20/30

  Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED] · CPC title

• Y02B70/10

  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 · CPC title

• H02M3/33571 Primary

  Half-bridge at primary side of an isolation transformer · CPC title