Patent ID: 7671487

Claim:
A control method for an uninterruptible power supply having a power input terminal for receiving a first AC voltage, a battery module, an AC/DC converter for receiving the first AC voltage through the power input terminal and converting the first AC voltage into a DC voltage, a charger circuit, an inverter for converting the DC voltage into a second AC voltage, a bypass route, a switch, a controller, and a power output terminal, the control method comprising the steps of: (a) determining if a peak voltage of the first AC voltage, a frequency of the first AC voltage, or a phase difference between the first AC voltage and the second AC voltage is abnormal; and (b) if it is determined that the peak voltage of the first AC voltage, the frequency of the first AC voltage, or the phase difference between the first AC voltage and the second AC voltage is normal, supplying the first AC voltage to the power output terminal through the bypass route and the switch, wherein the peak voltage, phase and frequency of the second AC voltage are substantially identical to those of the first AC voltage; and if it is determined that the peak voltage of the first AC voltage, the frequency of the first AC voltage, or the phase difference between the first AC voltage and the second AC voltage is abnormal, switching the switch to supply the second AC voltage to the power output terminal through the switch, and then the peak voltage and frequency of the second AC voltage being respectively adjusted to a rated peak voltage and a rated frequency of the first AC voltage.