Systems and methods to reduce magnetic flux in a transformer in a switched mode power supply

Patent metadata

Field	Value
Publication number	US-11077514-B2
Application number	US-201715786013-A
Country	US
Kind code	B2
Filing date	Oct 17, 2017
Priority date	Oct 17, 2017
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

Systems and methods to reduce magnetic flux in a switched mode power supply are disclosed. An example welding-type power supply includes a switched mode power supply, including a transformer configured to transform an input voltage to a welding-type voltage; switches configured to control a voltage applied to the primary winding of the transformer; a current detector configured to measure a current through the primary winding; a flux accumulator configured to determine a net flux in the transformer based on a number of volt-seconds applied to the primary winding of the transformer; and a controller configured to: control duty cycles of the switches based on the net flux; and set a value of the net flux in response to the current through the primary winding satisfying a current threshold.

First claim

What is claimed is:

1. A welding-type power supply, comprising:
a switched mode power supply, including a transformer configured to transform an input voltage to a welding-type voltage;
switches configured to control a voltage applied to the primary winding of the transformer;
a current detector configured to measure a current through the primary winding;
a flux accumulator configured to determine a net flux in the transformer based on a number of volt-seconds applied to the primary winding of the transformer; and
a controller configured to:
control duty cycles of the switches based on the net flux;
receive a signal representative of the current through the primary winding measured by the current detector; and
set a value of the net flux to a predetermined net flux value in response to the current through the primary winding satisfying a current threshold, wherein the current threshold is at least one of a positive threshold current or a negative threshold current.

2. The welding-type power supply as defined in claim 1 , wherein the current threshold is the positive threshold current.

3. The welding-type power supply as defined in claim 2 , wherein the controller is configured to set the value of the net flux to a positive flux saturation value of the transformer in response to the current through the primary winding satisfying the positive threshold current.

4. The welding-type power supply as defined in claim 1 , wherein the current threshold is a negative threshold current.

5. The welding-type power supply as defined in claim 1 , wherein the current detector comprises at least one of a current transformer, a Hall effect sensor, a sense resistor, or a magnetoresistive current sensor.

6. The welding-type power supply as defined in claim 1 , wherein the controller is configured to control duty cycles of the switches to reduce the value of the net flux from a saturation value while continuing to generate an output from the welding-type power supply.

7. The welding-type power supply as defined in claim 1 , wherein the controller is configured to count a number of occurrences of the current through the primary winding satisfying the current threshold and, in response to the number of occurrences satisfying a threshold number, control the switched mode power supply or the switches to stop a current output.

8. The welding-type power supply as defined in claim 1 , wherein the controller is configured to count a number of occurrences of the current through the primary winding satisfying the current threshold and, in response to the number of occurrences satisfying a threshold number, control the switches to change a welding parameter.

9. The welding-type power supply as defined in claim 1 , wherein the controller is configured to count a number of occurrences of the current through the primary winding satisfying the current threshold and, in response to the number of occurrences satisfying a threshold number, change at least one component of a control loop.

10. A welding-type power supply, comprising:
a switched mode power supply, including a transformer configured to transform an input voltage to a welding-type voltage;
switches configured to control a voltage applied to the primary winding of the transformer;
a current detector configured to measure a current through the primary winding;
a flux accumulator configured to determine a net flux in the transformer based on a number of volt-seconds applied to the primary winding of the transformer; and
a controller configured to:
control duty cycles of the switches based on the net flux;
receive a signal representative of the current through the primary winding measured by the current detector;
determine whether the current through the primary winding satisfies a current threshold, the current threshold comprising at least one of a positive threshold current or a negative threshold current; and
set a value of the net flux in response to the current through the primary winding satisfying the current threshold, wherein the controller is configured to at least one of set the value of the net flux to a positive flux saturation value of the transformer in response to the current through the primary winding satisfying the positive threshold current or set the value of the net flux to a negative flux saturation value of the transformer in response to the current through the primary winding satisfying the negative threshold current.

11. A method to control a welding-type power supply, comprising:
transforming an input voltage to a welding-type voltage via a transformer having a primary winding and a secondary winding;
controlling switches to control a voltage applied to the primary winding of the transformer;
determining a net flux in a primary winding of a transformer of a switched mode power supply based on a number of volt-seconds applied to the primary winding of the transformer;
measuring a current through the primary winding using a current detector; and
in response to the current through the primary winding measured by the current detector satisfying a current threshold, setting a value of the net flux to indicate magnetic saturation of the transformer, wherein the current threshold is at least one of a positive threshold current or a negative threshold current.

12. The method as defined in claim 11 , further comprising comparing the current to the positive threshold current corresponding to a positive saturation flux in the transformer.

13. The method as defined in claim 12 , wherein the setting of the value of the net flux comprises setting the value of the net flux to a positive flux saturation value of the transformer in response to the current satisfying the positive threshold current.

14. The method as defined in claim 11 , further comprising comparing the current to the negative threshold current corresponding to a negative saturation flux in the transformer.

15. The method as defined in claim 14 , wherein the setting of the value of the net flux comprises setting the value of the net flux to a negative flux saturation value of the transformer in response to the current satisfying the negative threshold current.

16. The method as defined in claim 11 , further comprising controlling duty cycles of a plurality of switches of the switched mode power supply based on the net flux, the duty cycles of the switches controlling a voltage applied to the primary winding of the transformer.

17. The method as defined in claim 11 , further comprising controlling duty cycles of the plurality of switches of the switched mode power supply to reduce the value of the net flux from a saturation value while continuing to generate an output from the welding-type power supply.

18. The method as defined in claim 11 , further comprising:
counting a number of occurrences of the current through the primary winding satisfying the current threshold; and
in response to the number of occurrences satisfying a threshold number, controlling the switched mode power supply to stop a current output.

19. The method as defined in claim 11 , further comprising:
counting a number of occurrences of the current through the primary winding satisfying the current threshold; and
controlling the switched mode power supply to change a welding parameter in response to the number of occurrences satisfying a threshold number.

20. The method as defined in claim 11 , further comprising:
counting a number of occurrences of the current through the primary winding satisfying the current threshold

Assignees

• Illinois Tool Works

Inventors

• Anders Adam E
• Schwartz Brian
• Nelson Andrew D
• Vogel Bernard J

Classifications

• H02M3/33573

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

• H02M3/33571

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

• H02M1/0077

  Plural converter units whose outputs are connected in series · CPC title

• B23K9/1056

  by using digital means (B23K9/1068 takes precedence) · CPC title

• H02M1/10

  Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from AC or DC · CPC title