Systems and Methods to Estimate Magnetic Flux in a Switched Mode Power Supply

Patent metadata

Field	Value
Publication number	US-2018302002-A1
Application number	US-201715489321-A
Country	US
Kind code	A1
Filing date	Apr 17, 2017
Priority date	Apr 17, 2017
Publication date	Oct 18, 2018
Grant date	—

Abstract

Systems and methods to estimate magnetic flux in a switched mode power supply are disclosed. An example welding-type power supply includes a switched mode power supply, comprising: a transformer configured to transform an input voltage to a welding-type voltage; a capacitor in series with a primary winding of the transformer; and switches configured to control a voltage applied to a series combination of the primary winding of the transformer and the capacitor; a voltage estimator coupled to the transformer and configured to output a signal representative of an alternating-current (AC)-coupled voltage at the capacitor; and a flux accumulator to determine a net flux in the transformer based on the voltage applied to the series combination of the primary winding of the transformer and the capacitor

First claim

What is claimed is:

1 . A welding-type power supply, comprising:
a switched mode power supply, comprising:
a transformer configured to transform an input voltage to a welding-type voltage;
a capacitor in series with a primary winding of the transformer; and
switches configured to control a voltage applied to a series combination of the primary winding of the transformer and the capacitor;
a voltage estimator coupled to the transformer and configured to output a signal representative of an alternating-current (AC)-coupled voltage at the capacitor; and a flux accumulator configured to determine a net flux in the transformer based on the voltage applied to the series combination of the primary winding of the transformer and the capacitor.

2 . The welding-type power supply as defined in claim 1 , further comprising a current transformer coupled to the capacitor, the voltage estimator to determine the AC-coupled voltage at the capacitor by measuring current flowing through the current transformer.

3 . The welding-type power supply as defined in claim 2 , wherein the voltage estimator further comprises an integrator and a filter configured to convert the current to a measurement of the AC-coupled voltage across the capacitor.

4 . The welding-type power supply as defined in claim 1 , further comprising a controller configured to control the switches based on the net flux in the transformer and the signal representative of the AC-coupled voltage at the capacitor.

5 . The welding-type power supply as defined in claim 4 , wherein the controller is configured to control the switches to maintain the net flux in the transformer within a predetermined amount from zero.

6 . The welding-type power supply as defined in claim 4 , wherein the controller is configured to apply a corrective factor to the net flux for controlling the switching when the signal representative of the AC-coupled voltage is outside of a range.

7 . The welding-type power supply as defined in claim 1 , wherein the voltage estimator is configured to measure the voltage of the capacitor, measuring the voltage at the primary of the transformer, measuring a voltage at a secondary winding of the transformer, or measuring a voltage at a third winding of the transformer.

8 . The welding-type power supply as defined in claim 1 , wherein the flux accumulator is configured to determine the net flux in the transformer based on the signal representative of the AC-coupled voltage.

9 . The welding-type power supply as defined in claim 8 , further comprising a controller configured to modify duty cycles of the switches based on the net flux in the transformer.

10 . The welding-type power supply as defined in claim 1 , wherein the switched mode power supply is a stacked full bridge configuration, a half bridge configuration, or a full bridge configuration.

11 . A method, comprising:
generating a signal representative of an alternating-current (AC)-coupled voltage at a capacitor coupled to a primary of a transformer of a switched mode power supply; determining a net flux in the transformer; and controlling switches of the switched mode power supply to apply a voltage to the transformer based on the net flux in the transformer and the signal representative of the AC-coupled voltage at the capacitor.

12 . The method as defined in claim 11 , further comprising applying a corrective factor to the net flux when the signal representative of the AC-coupled voltage is outside of a range.

13 . The method as defined in claim 11 , wherein the generating of the signal representative of the AC-coupled voltage comprises measuring current through a current transformer coupled to the primary of the transformer.

14 . The method as defined in claim 13 , wherein the generating of the signal representative of the AC-coupled voltage further comprises integrating and filtering samples of the current through the current transformer.

15 . The method as defined in claim 14 , further comprising determining a corrective factor based on the signal, the determining of the net flux in the transformer being based on the corrective factor.

16 . The method as defined in claim 11 , wherein the controlling of the switches comprises maintaining the net flux in the transformer within a predetermined amount from zero.

17 . The method as defined in claim 11 , wherein the determining of the net flux in the transformer is based on the signal representative of the AC-coupled voltage.

18 . The method as defined in claim 11 , wherein the controlling of the switches comprises modifying duty cycles of the switches based on the net flux in the transformer.

19 . The method as defined in claim 11 , wherein the controlling of the switches comprises controlling a stacked full bridge configuration, a half bridge configuration, or a full bridge configuration.

20 . The method as defined in claim 11 , wherein the determining of the AC-coupled voltage comprises at least one of measuring the voltage at the capacitor, measuring the voltage at the primary of the transformer, measuring the voltage at a secondary winding of the transformer, or measuring the voltage at a third winding of the transformer.

21 . The method as defined in claim 11 , further comprising controlling the switched mode power supply to transform an input voltage to a welding-type voltage or a welding-type current.

22 . A welding-type power supply comprising a switched mode power supply and a flux accumulator configured to monitor a voltage at a capacitor coupled in series to a transformer to estimate magnetic flux in the transformer.

Assignees

• Illinois Tool Works

Inventors

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

Classifications

• B23K9/1006

  Power supply · CPC title

• H02M5/4585 Primary

  having a rectifier with controlled elements · CPC title

• H02M1/4233

  using a bridge converter comprising active switches · CPC title

• H02M1/40 Primary

  Means for preventing magnetic saturation · CPC title

• H02M7/4803

  with means for reducing DC component from AC output voltage · CPC title