Uninterruptible power supply

The invention discloses an uninterruptible power supply, which comprises a rectifier circuit generating DC voltages, an energy storing unit, an inverter circuit for switching the DC voltages into three-phase modulating voltages, a filtering circuit, a bypass switch circuit and a control circuit, wherein the bypass switch circuit makes three-phase load voltages used as a three-phase electric supply or three-phase inverter voltages; and the control circuit controls the operation of the uninterruptible power supply. When the three-phase electric supply is interrupted or abnormal, the bypass switch circuit and the inverter circuit work; at the moment that a second inductive load works and in the later steady state, the control circuit can adopt magnetic flux compensation strategies in different operating modes to adjust the value of the three-phase load voltages, thereby compensating or correcting the magnetic flux of the second inductive load; and therefore, the magnetic flux distribution of the second inductive