Power converter and control method therefor, uninterruptible power supply, and power supply system

A micro inverter connected between a photovoltaic module and a load or a power grid, the micro inverter comprising:

• a transformer comprising
• a primary-side winding,
• a first secondary-side winding, and
• a second secondary-side winding;
• a first power conversion circuit, wherein an input of the first power conversion circuit is configured to connect to the photovoltaic module, an output of the first power conversion circuit is connected to the primary-side winding, and the first power conversion circuit is configured to convert a direct current to a high-frequency alternating current;
• a second power conversion circuit, wherein an input of the second power conversion circuit is connected to the first secondary-side winding, an output of the second power conversion circuit is configured to connect to the load or the power grid, and the second power conversion circuit is configured to convert a high-frequency alternating current boosted by the transformer to an alternating current adapted to the power grid or the load;
• an energy storage buffer circuit comprising a pair of transistors, wherein the pair of transistors are reversely connected in series to form a bidirectional switch and the energy storage buffer circuit is connected to the second secondary-side winding;
• and
• a controller configured to:
• control an input voltage of the first power conversion circuit,
• adjust a working voltage of the photovoltaic module connected to the micro inverter, and
• perform maximum power point tracking on the photovoltaic module;
• and
• the controller is further configured to:
• control the energy storage buffer circuit to perform charging in a first time period, so that energy from the first power conversion circuit is absorbed by using the transformer to perform energy buffering;
• and
• control the energy storage buffer circuit to perform discharging in a second time period, so that energy is transferred to the second power conversion circuit by using the transformer, wherein the second time period is after the first time period.