Charging and discharging device and charging and discharging system of electric vehicle

A charging and discharging device, comprising:

• a transformer comprising a primary winding and multiple secondary windings, which comprises at least a first secondary winding and a second secondary winding;
• multiple ports electrically connected to the primary winding and the multiple secondary windings of the transformer, respectively, wherein the multiple ports at least comprise:
• a first port electrically connected to the primary winding via a first conversion circuit;
• a second port electrically connected to the first secondary winding via a second conversion circuit;
• and
• a third port electrically connected to the second secondary winding via a third conversion circuit;
• and
• a first controllable switch connected between the first conversion circuit and the primary winding;
• wherein a voltage at the first port of the charging and discharging device is a first voltage, a voltage at the second port is a second voltage, and a voltage at the third port is a third voltage.