Power supply system

A power supply system, comprising:

• an isolated AC-to-DC power conversion unit that converts a system input voltage into a first DC voltage, wherein the first DC voltage is provided to a first DC bus;
• an isolated DC-to-DC power conversion unit electrically connected with the isolated AC-to-DC power conversion unit through the first DC bus, wherein the first DC voltage from the first DC bus is converted into a second DC voltage by the isolated DC-to-DC power conversion unit, and the second DC voltage is provided to a load, wherein a main power circuit in the isolated DC-to-DC power conversion unit is an LLC circuit or a boost-SRC circuit, and a voltage value of the second DC voltage is between 0.5V and 60V;
• and
• an energy storage unit electrically connected with the first DC bus, and comprising a battery, wherein when the isolated AC-to-DC power conversion unit works normally, the energy storage unit is charged to a floating charge state, and a voltage value of the first DC voltage is between 380V and 1500V.