Patent ID: 9583976
Date: 2017-02-28
CPC Classifications: H02J

Claim:
1. A power supply unit comprising: a relay that includes a first input terminal to which primary alternating-current power is input and a second input terminal to which secondary alternating-current power is input, and outputs one of the primary alternating-current power and the secondary alternating-current power; a first power conversion unit that is coupled to an output terminal of the relay, and converts alternating-current power output from the relay, into direct-current power; a second power conversion unit that is coupled to an output side of the first power conversion unit and converts output power of the first power conversion unit into direct-current power of a predetermined voltage; a power output terminal that outputs the direct-current power converted by the second power conversion unit; and a control unit that couples the first input terminal to the output terminal when a voltage of output power of the first power conversion unit is greater than or equal to a predetermined threshold value, and couples the second input terminal to the output terminal when the voltage of the output power of the first power conversion unit becomes less than a predetermined threshold value.