US Patent 7944089 Uninterruptible power supply module

An uninterruptible power supply module is provided. The uninterruptible power supply module comprises an input terminal, a direct-current voltage source, a control module, a control arm-bridge module, an inductive element, a power source selection switch, and a switch element. The switch element is turned on before the power source selection switch is connected to the inductive element so that the direct-current voltage supplied by the direct-current voltage source is modulated by the control arm-bridge module to generate an output alternating current voltage to the load. And the switch element is turned off, i.e. not conducting electricity, after the power source selection switch is connected to the inductive element and the direct-current voltage source. Thereby, the use life of the power source selection switch element and the reliability of the uninterruptible power supply module are both increased.