JPH0318151B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a detection coil used in a measuring device for measuring high current pulses, and more particularly to an improvement in a method of winding a Rogowski coil.

Conventionally, a Rogowski coil has been used as a detection coil to measure high current pulses with peak values on the order of tens of KA to several KA and pulse widths on the order of microseconds to nanoseconds.

When current is detected using the Rogowski coil described above, a detection output obtained by time-differentiating the current to be measured is applied to a display device such as an oscilloscope through an integrating circuit to measure the current.

The configuration of the Rogowski coil described above is as shown in FIG. The coil 3 is unwound in turns, and the current is determined by measuring the voltage between the beginning of the spiral coil and the end of the helical coil unwound in one turn.

The high current measuring means using a Rogowski coil as a detection means will be described in more detail.The lead 4 through which the current to be measured flows is arranged so as to pass through the center of the core 1.
The equivalent circuit when the current to be measured is passed in the direction of the arrow in the figure, a capacitor C is connected between the terminals of the Rogowski coil, and a resistor R is connected in series with one terminal of the Rogowski coil is shown in Figure 2. It can be expressed. In FIG. 2, L is the inductance component of the Rogowski coil, and e is the electromotive force generated in the Rogowski coil by the magnetic field generated by the current to be measured flowing through the lead 4.

The circuit equation for the above equivalent circuit is that the effective length of the Rogowski coil is s, the number of turns is n, the uniform magnetic constant of the coil is μ, the cross-sectional area is A, the current flowing through the measurement circuit is i,
When the measured current is I(t), it can be expressed as e=Ldi/dt+Ri+1/C∫ ^t ₀ idt (1) e=(μA/s) ndi(t)/dt (2).

If the highest frequency among the main frequency components of the measured current I(t) is expressed as Wm, then R≫WmL, t≪
If the RC condition is met, then ie/R, so the output voltage V is as follows: V=1/C∫ ^t ₀ idt=1/RCμA/snI(t)...(3) Find the output voltage V. By this, the measured current I(t) can be determined.

If R≫WmL does not hold, use a resistor R ₀ instead of capacitor C to satisfy R+R ₀ ≪wL. V=R ₀ ∫ ^t ₀ (e/L)dt=(R ₀ /n )I(t) (4) The measured current I(t) can be obtained from L=μn ² A/s.

As described above, when the Rogowski coil is viewed from the plane direction perpendicular to the direction in which the current to be measured flows from the back side to the front side of the paper, it is made as shown in Fig. 3, and the helical coil 2 and the one-turn coil 3 have the same area. Therefore, it is difficult to cancel magnetic field fluctuations in the direction of the measurement current. Furthermore, if the magnetic field in the direction of the measurement current varies locally over time due to external magnetic field (noise) components, the Rogowski coil will detect these, resulting in a deterioration of the S/N ratio. It was hot.

The present invention proposes a detection coil that is an improved version of the Rogowski coil without its drawbacks, as described above.
Its characteristic feature is that the spiral coil and the one-turn coil are wound so that they have the same area, so that noise magnetic fields are not detected.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 4 to 6.

FIG. 4 is a perspective view showing a coil winding state of an improved Rogowski coil of the present invention, and FIG. Circular coil parts 5a, 5b, 5c
..., first extending portions 6, 6... communicating with the circular coil 5 toward the center of the ring-shaped core 1, and forming a loop in a direction orthogonal to the first extending portion. Small loop coils 7, 7... forming turns
and second extending portions 8, 8, which communicate with the small loop coils 7, 7, and continue to the starting ends of the next circular coil portions 5b, 5c, and wind these components around the core 1 in sequence. At the end of the ring-shaped circular coil 5, the one-turn coil 3 is connected to the circular coil portions 5a, 5, similar to the conventional Rogowski coil shown in FIGS. 1 and 3.
The coil 5 is wound around the circumference of the circular coil 5, and the voltage between the final point of winding and the starting point of the circular coil is measured.

According to the coil winding described above, the detection coil is constructed as shown in FIG. 5 when viewed in plan, so that the circular coil 5 composed of the circular coil parts 5a, 5b, 5c, etc. has one turn. Completely overlap the coils, these are wound in opposite directions to each other,
Furthermore, since the currents flow in the extension parts 6 and 8 in opposite directions, noise in the direction of the measurement current can be canceled, and the temporal change in the magnetic field component in the direction of the measurement current is locally different. However, compared to conventional Rogowski coils, it is not detected as noise, so the S/N ratio can be improved. Incidentally, a system diagram for measuring high current using the above-mentioned detection coil is shown in FIG. Reference numeral 9 denotes the detection coil detailed in FIGS. 4 and 5, and the output terminal of the coil provides an output obtained by time-differentiating the current to be measured.
The output may be passed through an integrating circuit 10 and the integrated output may be applied to a display device 11 such as an oscilloscope to measure the current.

Since the detection coil of the present invention is constructed as described above, the area of the circular coil 5 composed of the circular coil portions 5a, 5b, . It has the feature of being able to cancel and improve the S/N.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a conventional Rogowski coil, Fig. 2 is an equivalent circuit of Fig. 1, Fig. 3 is a plan view of the Rogowski coil of Fig. 1, and Fig. 4 is a Rogowski coil of the present invention. FIG. 5 is a plan view of FIG. 4;
FIG. 6 is a system diagram showing a current measuring device using the detection coil of the present invention. 1... Core, 2... Coil, 3... Return coil, 4... Lead, 5... Circular coil, 5a,
5b...5n...Circular coil part, 6...First extension part, 7...Small loop coil, 8...Second extension part, 9...Detection coil, 10...Integrator circuit, 11
...Display device.

Claims (1)

[Claims] 1. A plurality of intermittent arc-shaped circular coil portions constituting a ring-shaped circular coil, and first and second extending portions continuous from both ends of the intermittent circular coil portions toward the center of the ring-shaped circular coil. A small loop coil is arranged in a direction orthogonal to the circular coil in the plane by connecting the first and second extension parts adjacent to the coil, and the end of the circular coil is folded back along the ring-shaped circular coil part. A detection coil characterized by having a one-turn coil.