| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the AC zero cross point by connecting, in series, two reactors made of core material having DC superposition properly capable of securing a high inductance value with different applied current values. SOLUTION: For a filter circuit 4, two reactors L2 and L4 and L3 and L5 made of core material having DC superposition property capable of securing a high inductance value with different applied current values are connected each in series as reactors. Here, the reactors L2 and L3 are made, using the core material capable of securing a high inductance value even in a large current application area, for example, the core material made of amorphous alloy, and the reactors L4 and L5 are made, using the core material capable of securing a higher inductance value than the reactors L2 and L3 only in a low current applied region, for example, a dust core. Hereby, the AC zero cross point of a sine wave AC current can be detected accurately with a small- sized reactor, and the downsizing can be facilitated. |
