System and method for determining output current and converter employing the same

For use with a power converter having an output capacitor and a component coupled thereto, a method of determining an output current of said power converter, comprising:

• developing a capacitor signal representing a current through said output capacitor from a voltage observed across one of a resistor of an observer circuit having a capacitor series-coupled to said resistor and an inductor of an observer circuit having a resistor series-coupled to said inductor;
• sensing a characteristic of said component and developing therefrom a component signal representing a current through said component;
• and
• deriving an output signal representing said output current from said capacitor signal and said component signal.

A power converter, comprising:

• a power switching circuit;
• a rectifier, coupled to said power switching circuit;
• an output filter coupled between said rectifier and an output of said power converter and having an output capacitor and a component coupled thereto;
• and
• a system for determining an output current of said power converter, including:
• an observer circuit, including one of a series-coupled capacitor and resistor, and a series-coupled resistor and inductor, parallel-coupled to said output capacitor that develops a capacitor signal representing a current through said output capacitor from a voltage observed across one of said resistor of said series-coupled capacitor and resistor, and said inductor of said series-coupled resistor and inductor;
• a sensor circuit, coupled to said component, that senses a characteristic of said component and develops therefrom a component signal representing a current through said component;
• and
• a summer circuit, coupled to said observer and sensor circuits, that derives an output signal representing said output current from said capacitor signal and said component signal.