JPH0261710B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a current detector using a magnetoelectric conversion element such as a Hall element.

Below, a current detector using a Hall element (hereinafter referred to as
This will be explained using Hall CT (abbreviated as Hall CT) as an example.

FIG. 1 is an explanatory diagram of the principle of Hall CT. In the figure, 1 is a conductor, 2 is a magnetic core, 3 is a Hall element, 4 is a Hall voltage output lead wire, 5 is a gap region, and 6 is a Hall voltage output terminal.

In Figure 1, conductor 1 through which the current to be measured I _f flows
When passed through the magnetic core 2, a magnetic field generated by the current to be measured is applied to the core 2. The strength of the magnetic field generated in the air gap region 5 provided in the magnetic path of the core 2 is
If the voltage is converted into a voltage using the Hall element 3, which is a magnetoelectric conversion element, and taken out to the terminal 6 via the lead wire 4, a Hall voltage proportional to the current value I _f to be measured can be obtained as a result. A problem with such a conventional Hall CT is that when the current to be measured changes suddenly, the transient response is poor. The cause of the deterioration of the transient characteristics of the Hall CT is that the magnetic flux interlinked with the Hall voltage output lead wire 4 drawn out from the Hall element semiconductor 3 fluctuates as the current to be measured changes, and as a result, electromagnetic induction occurs in the lead wire 4. This is because a voltage is generated, which is added to or subtracted from the Hall voltage and appears at the Hall voltage output terminal 6, which disturbs the Hall voltage that is originally desired to be measured.

This will be further explained with reference to FIG.

FIG. 2 is an explanatory diagram showing the configuration of a Hall element portion in a conventional Hall CT. In the same figure,
12 is a magnetic field region of a magnetic field (magnetic flux density B) running in a direction perpendicular to the paper surface, b ₁ and b ₂ are bias current terminals of the Hall element semiconductor 3, and h ₁ and h ₂ are the Hall element semiconductor 3
Hall voltage terminals 13 and 14 are bias currents i _c
15 and 16 are Hall voltage output terminals, and 10 and 11 are Hall voltage output lead wires.

In FIG. 2, on the four sides of the Hall element side conductor 3, one set of two bias current terminals (b ₁ , b ₂ ) and one set of two Hall voltage terminals (h ₁ , _h2 ) are provided. The method of drawing out the lead wires for drawing out the bias current terminals b ₁ and b ₂ and the Hall voltage terminals h ₁ and h ₂ of the Hall element semiconductor 3 to the outside is as shown in FIG. The Hall voltage output lead wires 10 and 11 form a loop within the magnetic field region 12 including the straight line (shown as a broken line) connecting the terminals h ₁ and h ₂ in the Hall element semiconductor 3, so the magnetic field (magnetic flux density B), an electromagnetic induced electromotive force V _B (V _B =SdB/dt) is generated in the loop. (However, S is the area of the loop formed within the magnetic field region 12 and is shown with diagonal lines)
As a result, the voltage V _H generated between the Hall voltage output terminals 15 and 16 becomes V _H = _K.i.sub.c.B +SdB/dt (where K is the product sensitivity of the Hall element and _ic is the bias current). What we really want to measure as the Hall voltage here is the first term [K・i _c・B], but the second term
Since the term [SdB/dt] is added, it has been difficult to accurately detect direct current or high frequency current with transient fluctuations. In other words, if the current to be measured (therefore, the magnetic flux density B) is a sinusoidal alternating current, the voltage of the cosine wave as its differential value (dB/dt) is added to the Hall voltage to be measured. It was not possible to obtain the correct Hall voltage because a phase shift occurred.

Note that FIG. 3 _is an electrical equivalent circuit diagram of the _{configuration shown in} FIG. The relationship is _h + V _B.

The present invention eliminates the drawbacks of the prior art as described above, and provides a current detector using a magneto-electric transducer that can accurately detect DC currents with large transient fluctuations and high-frequency currents. It is intended to.

The main point of the configuration of the present invention is that in a current detector using a Hall element as a magnetoelectric conversion element, an electromagnetic induction voltage induced in a lead wire for extracting the Hall voltage of the Hall element placed in a magnetic field is positively induced. The two lead wires are the lead wire that is induced and the lead wire that is negatively induced.
By creating two routes and adding these two voltages while adjusting them using a resistor at the lead wire output end of the Hall element, the electromagnetic induction voltage is canceled out, and only the Hall electromotive force is generated at the lead wire end of the Hall element. It lies in the fact that it is made to appear.

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a configuration explanatory diagram showing one embodiment of the present invention. In this figure, the same parts as in FIG. 2 are given the same reference numerals. In addition, 17,1
8 and 19 are Hall voltage output lead wires,
R ₁ and R ₂ are each a resistance.

In FIG. 4, the Hall element semiconductor 3 includes bias current terminals b ₁ , b ₂ and Hall voltage terminals h ₁ , h _{2 .}
There is. Lead wires are connected to the terminals b ₁ and b ₂ from the bias current input/output terminal 13Y14 as shown. Further, the Hall voltage output lead wire 19 taken out from the terminal _h2 runs on an extension of the straight line (shown as a broken line) connecting the terminal _h1 and the terminal _h2 in a region where a magnetic field (magnetic flux density B) exists. and is connected to the Hall voltage output terminal 15. The two Hall voltage output lead wires 17 and 18 taken out from terminal _h1 are straight lines (broken lines) connecting terminals _h1 and _h2 , respectively.
The leads are positioned so as to form a closed loop within the magnetic field region 12, _one on each side _of a straight line containing Perform the wiring. These lead wires 17 and 18
is the Hall voltage output terminal 1 via resistors R ₁ and R ₂
Connected to 6.

When the lead wires are wired in this way, the first electromagnetic induction voltage V _B1 induced in the loop occupying the area S ₁ by the temporal change dB/dt of the magnetic flux density B in the magnetic field region 12, An equivalent circuit showing the relationship between the second electromagnetic induction voltage V _B2 induced in the loop occupying the area S ₂ and the Hall electromotive voltage v _h is shown in FIG. In FIG. 5, the resistance values of R ₁ and R ₂ are chosen to be sufficiently smaller than the resistance value of the load resistor _RL . When electromagnetic induced voltages V _B1 and V _B2 are generated in each loop circuit due to the temporal change dB/dt of magnetic flux density B in the magnetic field region, these induced voltages and resistance
By selecting the resistors R ₁ and R ₂ so that the voltage V _B of the equivalent power supply formed by R ₁ and R ₂ becomes 0V, the voltage that appears between the Hall voltage output terminals 15 and 16
V _H becomes equal to the Hall electromotive force V _h of the Hall element. As a result, the Hall effect using this Hall element is
CT allows accurate detection of DC currents and high-frequency currents that have transient fluctuations.

According to the present invention, it is possible to accurately detect DC currents with large transient fluctuations, high frequency currents, etc., which have been difficult with conventional current detectors using magnetoelectric transducers.

The present invention can be applied not only to Hall elements but also to methods for leading out lead wires of magnetoresistive elements and the like that are affected by electromagnetic induction.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the principle of a current detector using a Hall element, Figure 2 is an explanatory diagram showing the configuration of the Hall element part in a conventional current detector, and Figure 3 is an illustration of the electric current detector with the configuration shown in Figure 2. FIG. 4 is a configuration explanatory diagram showing one embodiment of the present invention, and FIG. 5 is an equivalent circuit diagram of the electric circuit shown in FIG. 4. Description of symbols, 1...Conductor, 2...Magnetic core, 3...Hall element, 4...Lead wire, 5...Gap region, 6...Hall voltage output terminal, 10, 11...Hall voltage output lead wire, 12...Magnetic field region, 13, 14...Bias current input terminal, 15, 16...Hall voltage output terminal.

Claims (1)

[Scope of Claims] 1. A current detector that detects a current by an electrical output obtained from a magnetoelectric transducer arranged in a magnetic field generated by the current to be detected, comprising: The first lead member taken out from the first outgoing terminal of the two outgoing outgoing terminals for taking out the output is arranged on an extension of the straight line connecting the two outgoing terminals and connected to the first output terminal. , Regarding the second and third two lead members taken out from the second outgoing terminal of the two outgoing terminals, one lead member is placed on each side of the straight line connecting the two outgoing terminals, respectively. form closed loops with approximately the same area with the straight line, and then are connected to the second output terminal via a resistor, and the induced voltages generated by each of the closed loops are mutually connected to each other at the second output terminal. By adjusting the resistance values of the resistors so that they cancel each other out, an electromagnetic induction voltage component due to magnetic field fluctuations is removed from the electrical output of the magnetoelectric conversion element obtained from the first and second output terminals. A current detector featuring: