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

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.

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.