Microinverter and current detection method

A current detection method, comprising:

• controlling four switching transistors in a secondary-side circuit of an inverter, the secondary-circuit circuit being connected to a secondary-side winding of a transformer to be turned on or off, wherein the secondary-side circuit is configured to convert an alternating current output by the secondary-side winding of the transformer into a power frequency alternating current, and output the power frequency alternating current to a power grid through an output port;
• and
• controlling, based on statuses of the four switching transistors and a current direction of the secondary-side winding of the transformer, two groups of controllable switches in a current detection circuit to be turned on or off, so that an integration filter circuit in the current detection circuit restores an output voltage of a sampling circuit in the current detection circuit, wherein the current detection circuit is located between the secondary-side winding of the transformer and the secondary-side circuit, and a current, a voltage, or a frequency of a restored alternating current obtained through restoration of the integration filter circuit is consistent with that of the alternating current output by the output port.