JP2000187048A - Watthour meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a watthour meter which can measure a power factor and a phase simultaneously together with electric energy. SOLUTION: One of an a.c. load voltage and an a.c. load current is converted into a control current and the other is converted into a magnetic field, which are impressed to a Hall element 1 (1a, 1b). The a.c. electric energy is measured from an output voltage of the Hall element 1. The electric field is applied to two or more Hall elements 1 and phases of control currents impressed to the Hall elements 1 are changed, whereby information on the load voltage and load current related to a phase is simultaneously measured with the electric energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC watt-hour meter using a Hall element, and more particularly, to a watt-hour meter capable of measuring a power factor and a phase simultaneously with measuring a power amount with one watt-hour meter. Things.

[0002]

2. Description of the Related Art As an AC watt-hour meter using a Hall element, one of a load voltage and a load current is converted to a control current, the other is converted to a magnetic field, and applied to the Hall element, respectively.
There is a type that measures the amount of power by a multiplication function of a Hall element. The watt hour meter using the Hall element utilizes a physical phenomenon that the output voltage of the Hall element is proportional to the product of the control current and the magnetic flux density which is the strength of the magnetic field. That is, when the control current and the magnetic flux density are correctly proportional to the load voltage and the load current, the output voltage of the Hall element is proportional to the instantaneous power (active power). Therefore, the integrated power amount (active integrated power amount) is obtained by integrating the output voltage of the Hall element, and by averaging the output voltage of the Hall element for a certain period,
Power (active power) is obtained. When measuring a power amount using a Hall element, a method of measuring an AC active power without a relative time difference (phase difference) for applying a control current and a magnetic flux density is generally used. In addition, a method is generally used in which one Hall element is used and only active power is measured.

[0003]

In the AC power system, the phase between the load voltage and the load current is important. Eliminating this phase difference makes it possible to transport power efficiently. Therefore, if not only the active power but also the phase information can be easily and simultaneously measured by the watt-hour meter, the efficiency of power transport can be improved by effectively utilizing the measurement result. However, the conventional watt-hour meter uses only one Hall element,
Since only active power is measured, phase information cannot be measured. If a plurality of conventional watt-hour meters are used, phase information can be obtained. For example, active power and reactive power can be measured, and a power factor can be measured from the active power and reactive power. However, when a plurality of watt-hour meters are used, the cost of the watt-hour meter is increased by the number of the watt-hour meters, which increases the cost.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a watt hour meter capable of measuring a power amount and measuring a power factor and a phase simultaneously with one watt hour meter.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention converts one of an AC load voltage and a load current into a control current and converts the other into a magnetic field to convert the control current and the magnetic field. Is applied to the Hall elements, and in a watt hour meter that measures the AC power amount based on the output voltage of the Hall elements, a control current is applied to the Hall elements by applying the magnetic field to two or more Hall elements. , The information about the phase between the load voltage and the load current is measured simultaneously with the measurement of the electric energy.

The active power and the reactive power may be measured simultaneously by shifting the phases of the control currents applied to the respective Hall elements by 90 ° with respect to each other.

[0007] The two or more Hall elements may be housed in the same package.

[0008] The two or more Hall elements may be formed on the same substrate.

The Hall element may be formed of a conductive layer of 5 μm or less formed on a semi-insulating GaAs single crystal, and the conductive layer may have a sheet resistance of 200Ω to 10 kΩ.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

As shown in FIG. 1, the watt hour meter according to the present invention has two Hall elements 1a and 1b and a common magnetic field B applied to these Hall elements 1a and 1b in proportion to an AC load current. A magnetic field applying means (not shown) for applying, a control current applying circuit 2a, 2b for applying a control current proportional to an AC load voltage V to these Hall elements 1a, 1b, and a Hall element 1a, 1b. A phase shifter 3 for changing the phase of the control current to be applied, and a Hall element 1a,
Amplifying circuits 4a and 4 for extracting and amplifying the output voltage of 1b
b, and a circuit (not shown) for measuring information on the phase of the load voltage and the load current from the electric energy obtained by the two amplifier circuits 4a and 4b.

The watt hour meter according to the present invention simultaneously measures the active power and the reactive power by shifting the phases of the control currents applied to the respective Hall elements 1a and 1b by 90 ° with respect to each other. It is preferable to measure the power factor from the active power and the reactive power.

The watt hour meter shown in FIG. 1 has Hall elements 1a and 1b.
The active power and the reactive power are measured at the same time by shifting the phases of the control currents applied to each other by 90 °. That is, when a control current proportional to the AC load voltage V is applied to each of the Hall elements 1a and 1b, the phase shifter 3
Thus, the phase of the control current flowing through the second Hall element 1b is delayed by 90 ° with respect to the control current flowing through the first Hall element 1a. Further, the two Hall elements 1a and 1b are housed close to each other in the same package, and a magnetic flux density proportional to the load current is simultaneously applied by the same magnetic circuit (not shown). ing. That is, in the first Hall element 1a, the control current and the magnetic flux density have the same phase, and the first Hall element 1a amplifies the output voltage.
The amplifier circuit 4a outputs a voltage proportional to the active power. On the other hand, in the second Hall element 1b, the phase of the original control current and the phase of the magnetic flux density are shifted by 90 °, and the second amplifier circuit 4b that amplifies the output voltage of the second Hall element 1b outputs reactive power (slow current). Output voltage). Using these instantaneous active power and reactive power, other characteristics related to load voltage and load current, such as power factor, can be easily calculated. Efficiency can be increased.

Next, another embodiment of the present invention will be described.

In addition to the configuration shown in FIG. 1, there is provided an active power integrating display circuit for integrating and displaying active power output from the first amplifier circuit 4a, and integrating the reactive power output from the second amplifier circuit 4b. And a reactive power integration display circuit for displaying. Actually, when these integration display circuits were manufactured,
Reactive power information was found to be useful for improving the efficiency of power transport.

The watt-hour meter shown in FIG.
A Hall element formed by implanting Si ions at an acceleration of 150 kV and implanting them on the s single crystal is used. The thickness of the conductive layer formed by the ion implantation method was about 0.3 μm, and the sheet resistance of the conductive layer was about 800Ω. The Hall element has good linearity with respect to the magnetic flux density of the Hall voltage.
It has been found that the linearity of the input resistance with respect to the temperature and the linearity of the product sensitivity with respect to the temperature are good in the temperature range of 40 ° C. to 100 ° C.

Next, an embodiment relating to the shape of the Hall element will be described.

As shown in FIG. 2A, the same substrate 2
Two patterns of the Hall element 1 having the same structure are formed on the zero. Further, as shown in FIG. 2B, three patterns of the Hall element 1 having the same structure are formed on the same substrate 20. Since these Hall elements 1 are manufactured by the same process and are arranged close to each other, there is little variation in performance, quality, and the like, and good thermal coupling facilitates temperature compensation. For temperature compensation, it is convenient to improve the thermal coupling, and it is preferable that the plurality of Hall elements 1 be arranged in the same package. Further, it is preferable that a circuit (IC circuit) for driving the Hall element 1 is also housed in the package and packaged integrally, and temperature compensation of the entire Hall element including the temperature characteristics of the drive circuit is performed.

The Hall element thus formed is:
It is suitable for use in the watt hour meter of the present invention. However, the plurality of Hall elements used in the watt hour meter of the present invention need not be formed in the same structure, and need not be formed on the same substrate.

As the Hall element used in the watt hour meter of the present invention, a GaAs Hall element is preferable. This is because the GaAs Hall element has a high Hall voltage with respect to the magnetic flux density, and has good linearity of the Hall voltage with respect to the magnetic flux density.
Furthermore, when the Hall element is formed of a conductive layer of 5 μm or less formed on a semi-insulating GaAs single crystal and the sheet resistance of the conductive layer is 200Ω to 10 kΩ, the Hall voltage with respect to the temperature in a wide temperature range is reduced. The rate of change is almost constant, which is suitable for temperature compensation.

[0021]

The present invention exhibits the following excellent effects.

(1) Since the power factor and the phase can be measured simultaneously with the measurement of the electric energy by one electric energy meter, the cost can be reduced and the measurement can be performed easily as compared with the case of using a plurality of conventional individual electric energy meters. It can be performed.

(2) It is possible to easily and inexpensively measure information on the phase of the load voltage and the load current, which are important for AC power transport.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a watt hour meter showing one embodiment of the present invention.

FIG. 2 is a plan view showing a pattern shape of a Hall element used in the watt hour meter of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hall element 1a 1st hall element 1b 2nd hall element 2a, 2b Control current application circuit 3 Phase shifter 4a 1st amplifier 4b 2nd amplifier

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ken Takahashi 3550 Kida Yomachi, Tsuchiura City, Ibaraki Pref. Hitachi Cable, Ltd. Advanced Research Center Co., Ltd. 905 (72) Inventor Koji Imaizumi 63-24 Sunakubo, Kawagoe-shi, Saitama

Claims (5)

[Claims] 1. An AC load voltage and a load current, one of which is converted into a control current, the other is converted into a magnetic field, and the control current and the magnetic field are applied to a Hall element. In the watt hour meter that measures the amount of AC power, the magnetic field is applied to two or more Hall elements, and the phase of the control current applied to each Hall element is changed, so that the measurement of the power is performed simultaneously. A watt hour meter for measuring information on a phase between the load voltage and the load current. 2. The active power and the reactive power are simultaneously measured by shifting the phases of control currents applied to respective Hall elements by 90 ° with respect to each other.
Watt-hour meter described. 3. The watt hour meter according to claim 1, wherein the two or more Hall elements are housed in the same package. 4. The watt hour meter according to claim 1, wherein said two or more Hall elements are formed on the same substrate. 5. The semiconductor device according to claim 1, wherein the Hall element is formed of a conductive layer of 5 μm or less formed on a semi-insulating GaAs single crystal, and the conductive layer has a sheet resistance of 200Ω to 10 kΩ. 4. The watt hour meter according to any one of 4 above.