Abstract: A first current detector detects an output current of a modular uninterruptible power supply apparatus. Each of a plurality of power conversion modules includes a resistive element and a second switch. The second switch connects the first current detector and the resistive element in parallel in an ON state. Each of first control circuits turns on the second switch when setting a corresponding power conversion module to an operating state, and turns off the second switch when setting the power conversion module to a stopped state. Each of the first control circuits detects a shared current of the corresponding power conversion module based on a current flowing through the resistive element when the second switch is in the ON state. Each of the first control circuits controls a power converter such that an output current of the power conversion module matches the shared current.

Abstract: An AC/DC converter converts an AC voltage supplied from an AC power supply into a first DC power supply voltage. A power supply line transmits the first DC power supply voltage to a plurality of power conversion modules and a bypass module. The bypass module includes a switch connected between the AC power supply and the load, and a first controller that operates upon receiving an operating power supply voltage based on the first DC power supply voltage to thereby control ON/OFF of the switch. Each power conversion module includes a power converter that converts power supplied from the AC power supply or a power storage device into AC power and supplies the AC power to the load, and a second controller that operates upon receiving an operating power supply voltage based on the first DC power supply voltage to thereby control the power converter.

Abstract: An uninterruptible power supply apparatus having a plurality of power conversion modules and a bypass module connected in parallel between an AC power supply and a load. Each of the power conversion modules includes a first terminal that receives AC power from the AC power supply, a second terminal connected to a power storage device, a third terminal for outputting AC power to the load, a converter, an inverter, and a first control circuit. The bypass module includes a switch connected between the AC power supply and the load, a first voltage detector that detects an AC voltage applied to the first terminal, a second voltage detector that detects a DC voltage applied to the second terminal, a third voltage detector that detects an AC voltage applied to the third terminal, and a second control circuit.