Photovoltaic Power Converters

A grid-tie solar power converter comprising:

• an input for receiving a direct current (DC) power input;
• a first stage for receiving the DC power input and including an output for providing a DC power output;
• a DC link coupled to the output of the first stage;
• a second stage coupled to the DC link and configured to convert DC power to an alternating current (AC) output power;
• a controller coupled to the second stage, the controller configured to:
• sample a DC link voltage of the DC link during a first cycle of an alternating output voltage of the second stage at one instance when the alternating output voltage is crossing zero volts in a first direction;
• determine a voltage difference between the DC link voltage sampled during the first cycle and a DC link voltage sampled during a previous cycle when the alternating output voltage was crossing zero volts in the first direction;
• estimate a DC link power based at least in part on the determined voltage difference;
• and
• control the AC power output by the second stage in a second cycle after the first cycle based at least in part on the estimated DC link power.