| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply device with a bridgeless power factor correction topology which improves power conversion efficiency in a high load condition.SOLUTION: A switching power supply device 1 includes: a capacitor C1; inductors L1, L2 connected to each phase of an AC power supply E1; rectification elements D1, D2 connecting the respective inductors L1, L2 to a positive electrode of the capacitor C1; switching elements Q1, Q2 connecting the respective inductors L1, L2 to a negative electrode of the capacitor C1; a relay element RY1 connected in parallel with the inductor L1; and a control circuit CNT1 for controlling on/off of the plurality of switching elements Q1, Q2 and the relay element RY1. At the time when an AC input current becomes zero, if the most recent effective value of the AC input current is equal to or more than a threshold, the relay element RY1 is turned on, and if the most recent effective value of the AC input current is less than the threshold, the relay element RY1 is turned off. |
