Power supply system

An uninterruptible power supply system, comprising:

• a power supply assembly electrically connected between an input power source and a load, wherein when an input power outputted from the input power source is normal, the power supply assembly converts the input power into a first DC power;
• a first auxiliary power circuit electrically connected between the power supply assembly and the load, and comprising:
• at least one first energy storage unit configured to provide a second DC power;
• and
• at least one first power converter electrically connected between the at least one first energy storage unit and the load and configured to convert the second DC power into a first individual auxiliary power, wherein the first auxiliary power circuit provides a first overall auxiliary power to the load according to the first individual auxiliary power;
• a second auxiliary power circuit electrically connected between the power supply assembly and the load and configured to provide a second overall auxiliary power to the load, wherein the second auxiliary power circuit comprises at least one second energy storage unit, wherein an energy density of the at least one second energy storage unit is greater than that of the at least one first energy storage unit, and a power density of the at least one first energy storage unit is greater than that of the at least one second energy storage unit;
• and
• a control unit configured to drive the first auxiliary power circuit to output the first overall auxiliary power to the load when the input power is normal and a first transient power required by the load is greater than a first upper limit rated value of an output power outputted from the power supply assembly, so as to compensate a difference value between the first transient power and the first upper limit rated value, wherein the first auxiliary power circuit is not driven when the first transient power required by the load is lower than or equal to the first upper limit rated value of the output power outputted from the power supply assembly, wherein when the input power is abnormal, the power supply assembly stops operating, and the control unit drives the second auxiliary power circuit to provide the second overall auxiliary power to the load.