| 摘要 |
<p>PROBLEM TO BE SOLVED: To highly precisely detect a direct current component contained in an alternating current, without using a highly precise Hall element type current transformer or a high-cut filter. SOLUTION: A direct current component detector 20 is composed of an electromagnetic type current transformer 21 with current transformation ratio of (n) and a Hall element type current transformer 22, and it is arranged in an alternating current main circuit 23. Total current of an alternating current IAC and a direct current component IDC are flowed in the main circuit 23, and a secondary circuit 21S of the transformer 21 outputs a current of IAC/n. An auxiliary coil 22A with a wound number of (n) is provided in a ring-like iron core 22C of the Hall element transformer 22 to be connected to the secondary circuit 21S, and a magnetic flux of the alternating current IAC out of magnetic fluxes resulting from IAC+IDC generated in the iron core 22C is offset each other with a magnetic flux generated in the auxiliary coil 22A. A remaining magnetic flux of the direct current component IDC is detected by a Hall element 22H provided in a gap of the iron core 22C.</p> |
