| 摘要 |
PROBLEM TO BE SOLVED: To avoid the occurrence of an excessive current flowing for maintaining power at the time of instantaneous lowering of a power supply voltage by power failure.SOLUTION: A converter 300 includes a multiphase diode bridge, and obtains a DC voltage Vfrom a multiphase AC power supply 100. A gate block 112 changes an operation of the converter 300 to an operation of a diode rectifier when detecting the power failure of the multiphase AC power supply 100. A low voltage detection part 120 detects whether the DC voltage Vfalls below a predetermined threshold or not. A voltage change ratio detecting part 121 detects power recovery of the DC voltage V. The gate block 112 returns the operation of the converter 300 to an ordinary operation when detecting the power recovery of the multiphase AC power supply 100 in a situation that the DC voltage Vdoes not fall below the predetermined threshold, and stops power supply from the multiphase AC power supply to the converter 300 when the DC voltage Vfalls below the predetermined threshold. A lowest voltage for avoiding rush currents to the multiphase diode bridge is adopted as the predetermined threshold. |
