Method and apparatus for deriving current for control in a resonant power converter

A system for measuring current in a power converter comprising:

• at least one photovoltaic (PV) module;
• and
• at least one power converter coupled to the PV module comprising:
• a resonant tank circuit with a capacitor, the resonant tank circuit is coupled to a DC input bridge and a first terminal of the capacitor is coupled to a ground of the DC input bridge;
• a voltage monitor coupled across the capacitor for measuring a voltage across the capacitor;
• and
• a resonant current calculation module for computing a tank current value, based on the voltage across the capacitor, of a tank current through the capacitor.

A method for measuring current in a power converter comprising:

• measuring a voltage across a capacitor of a resonant tank in a resonant power converter, wherein the resonant tank is coupled to a DC input bridge of the resonant power converter and wherein a terminal of the capacitor is coupled to a ground of the DC input bridge, wherein the voltage is measured by a voltage monitor coupled across the capacitor;
• measuring by a resonant current calculation module, a change in the voltage over time;
• and
• determining by the resonant current calculation module, a tank current value, based on the change in the voltage across the capacitor, of a tank current through the capacitor.