| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a D.C. current sensor capable of accurately measuring D.C. current over a wide range from a small-current region to a large-current region. SOLUTION: A Hall element 15 inserted into a gap 11 formed in a core 13 outputs a voltage according to a magnetic flux (ϕ0+ϕα) generated by a breakthrough current (I0+α). An offset coil 21 is wound on the core 13 by the number of turns N0, and an offset coil current control circuit 29 offsets a magnetic fluxϕ0 generated by an offset breakthrough current I0 to offset an offset width I0 for flowing a predetermined regulating current i0 (=I0/N0) through the offset coil 21. As a voltage proportional to the magnetic fluxϕαis derived from the Hall element 15 and is amplified by an amplifier 19 t0 obtain an output voltage E0, it is possible to obtain a breakthrough currentαby an output voltage E0. As the offset breakthrough current I0 is already known, it is possible to measure the breakthrough current (I0+α) accurately.</p> |
