JP2010066145A - Current measuring apparatus and current measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small, inexpensive, and easily installable current measuring apparatus and current measuring system safely constructed free of an electric shock and the like. <P>SOLUTION: A current transformer 3 detects a current in an electrical path to which an electric device is connected, and a current detection section 4 outputs a current proportional to a current value from the current transformer 3. A measurement control section 5 measures a current running to the electric device based on an electric signal from the current detection section 4. A power supply section 7 receives electric power from an external communication interface section to generate an operating voltage of the measurement control section 5. A communication control section 6 communicates data signals, such as measurement value data, with an external measurement controller via the communication interface section through a non-contact insulation structure such as electromagnetic inductive radio. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a measuring device for measuring the current of a circuit to be measured, and a current measuring system provided with the current measuring device, which are used for demand control for controlling the operation of the device and operating the device in a predetermined current range.

  Conventionally, in order to measure the power consumed by household appliances, etc., a power measuring device is installed by a professional contractor such as installing a sensor for current measurement and a voltage conversion transformer for voltage measurement on the circuit to be measured. Was attached. In order to simplify the construction, for example, the measuring instrument shown in Patent Document 1 integrates a conductive voltage detection unit having a sharp tip with a current sensor unit constituting a closed magnetic circuit, so that the sensor unit can be easily attached. It was composed.

Japanese Patent Laying-Open No. 2005-134233 (pages 6 to 7, FIGS. 1 to 7)

  The conventional measuring instrument shown in Patent Document 1 describes a technique for facilitating the attachment of the voltage and current detection unit, but actually acquires the power consumed by the part that measures power other than the measurement unit. Prevention of miswiring and easy installation of the measuring instrument unless it is facilitated, including the electrical wiring for the measurement and the interface (hereinafter also referred to as I / F) for retrieving the measured values. There was a problem that it was not possible.

  The present invention has been made to solve the above-mentioned problems, and has as its first object to obtain a current measuring device and a current measuring system that are small and inexpensive and can be easily installed. A second object is to obtain a current measuring device and a current measuring system capable of performing safe construction.

  A current measurement device according to the present invention includes a current detector that detects a current in an electric circuit to which an electric device is connected, a calculation unit that measures a current flowing through the electric device based on an output of the detector, and an external measurement controller A power supply unit that receives power from the communication interface unit and generates an operating voltage for the arithmetic unit, an external measurement controller, and communication of data signals such as measured value data via the communication interface unit with a non-contact insulation structure And a communication unit for performing.

  The current measuring device according to the present invention has a non-contact insulation structure such as electromagnetic induction radio for receiving power from the outside of the operating power of the arithmetic unit and the communication of the data signal such as measured value data with an external measurement controller. Since it comprised so that it could carry out, a current measuring device can be installed safely and easily without erroneous wiring, and size reduction and low cost can be achieved.

Embodiment 1 FIG.
FIG. 1 shows a configuration diagram of a current measuring device according to Embodiment 1 of the present invention. In FIG. 1, a current measuring device 1 is composed of a magnetic core having an open magnetic circuit or a closed magnetic circuit and a coil wound around the core, and L1 and L2 except for a neutral wire N of a single-phase three-wire electric circuit 2. A current transformer 3 arranged on each line, a current detector 4 for measuring a current signal obtained by the current transformer 3, and a current signal proportional to the current value flowing in each electric circuit 2 obtained from the current detector 4 The measurement control unit 5 is configured by a microcomputer or the like that measures the current flowing from the device to the electrical device, and the communication control unit 6 is configured to transmit the current value measured by the measurement control unit 5 to the outside.
The communication control unit 6 is connected to a communication I / F unit 8 having a plurality of I / F means, such as a paired wire that communicates by superimposing an AC signal on a DC voltage, a power supply type LAN (PoE), or USB. It has a function of transmitting a direction data signal and supply of operating power of the main body using a non-contact medium such as electromagnetic induction radio. The power supply unit 7 receives power transmitted from the communication I / F unit 8 through a non-contact medium such as electromagnetic induction radio via the communication control unit 6 and generates a power supply voltage necessary for the operation of the current measuring device 1 main body. .

FIG. 2 is a diagram illustrating the principle of the current transformer 3. In FIG. 2, a ring-shaped closed magnetic circuit core is illustrated for explanation, but what is used in the present embodiment is an open magnetic circuit configuration shown in FIG. 3 or a closed magnetic circuit configuration shown in FIG. 4. The current transformer 3 includes a detection coil for obtaining a voltage value proportional to the current IL flowing through the electric wire of the electric circuit 2 and a core wound with a bias coil for flowing a predetermined bias current ib. A predetermined magnetic flux is applied to the core. As shown in FIG. 5, the operating point can be maintained in a region where the magnetic field generated by the current and the magnetic flux density in the core are linear with respect to the change in the current IL.
In addition, the communication control part 6 comprises a communication part, the measurement control part 5 comprises a calculating part, and the current limiter 9 comprises an electric circuit breaker.

6 and 7 are diagrams showing in detail the circuit of the power supply unit 7 that generates the operation power supply of the main body 1 as the power transmission circuit 81 and the communication circuit 86 of the communication I / F unit 8 and the communication circuit 76 of the communication control unit 6. It is an example.
In the figure, reference numeral 80 denotes a communication means of the communication I / F unit 8, for example, a DC voltage superimposed on a pair line, a DC power supplied from a PoE cable, or a DC power supplied from a USB port. Reference numeral 84 denotes an excitation inverter of a power transmission resonance circuit 85 constituted by a series resonance circuit by a feeding coil and a resonance capacitor, and in this example, is constituted by four switching elements 84a, 84b, 84c and 84d. When power is not supplied, all four elements are in the OFF state. By repeating Off at the period of the resonance frequency of the power transmission resonance circuit 85, an alternating current is supplied to the power transmission resonance circuit 85 to generate an alternating magnetic field.

  The AC magnetic field generated by the power transmission resonance circuit 85 is radiated into the space, and is applied to the coil 71L of the power reception resonance circuit 71 configured as a parallel resonance circuit by the coil 71L and the capacitor 71C via a predetermined gap. An AC voltage is generated in the coil 71L by the magnetic field. This AC voltage is rectified by the diode 72, the commercial frequency component is smoothed by the smoothing circuit 73 constituted by the capacitors 73a and 73b, stabilized by the power supply regulator 74, and the fluctuation of the voltage is suppressed. Power is supplied to each part of the measuring device 1.

  FIG. 7 is an example of a diagram illustrating in detail the communication circuit 76 of the communication control unit 6 in the current measuring device 1 and the circuit of the communication circuit 86 in the communication I / F unit 8. The communication circuits 76 and 86 constitute the same circuit. In the figure, a communication processing unit 76c is a control unit of the communication control unit 6 configured by, for example, a microcomputer for performing communication control. Transmission data from the communication processing unit 76c is transmitted to a high-frequency signal generated by the carrier oscillation unit and an AND circuit. It is input and becomes an ASK (Amplitude Shift Keying) wave. This is amplified to a predetermined power by an amplifier, and the transmission / reception resonance circuit 76a is excited. The AC magnetic field generated by the transmission / reception resonance circuit 76a is applied to the transmission / reception resonance circuit 86a of the communication circuit 86 through a predetermined gap, and generates a high-frequency AC voltage. The high-frequency AC voltage output from the transmission / reception resonance circuit 86a is smoothed by a smoothing circuit, the high-frequency signal is removed, input to the comparator, and the binarized reception data is output, and the communication I / F unit 8 is output through the buffer. Is input to the control means 86c constituted by a microcomputer or the like.

  In the figure, a communication processing unit 86c is a control means of the communication I / F unit 8. Transmission data from the communication processing unit 86c is input to a high-frequency signal generated by a carrier oscillation unit and an AND circuit, and ASK (Amplitude Shift Keying) Wave. This is amplified to a predetermined power by an amplifier to excite the transmission / reception resonance circuit 86a. The AC magnetic field generated by the transmission / reception resonance circuit 86a is applied to the transmission / reception resonance circuit 76a of the communication circuit 76 to generate a high-frequency AC voltage. The high-frequency AC voltage output from the transmission / reception resonance circuit 76a is smoothed by a smoothing circuit, the high-frequency signal component is removed, input to the comparator, and binarized reception data is output, and communication in the current measuring means 1 is performed through the buffer. The data is input to the communication processing unit 76c that performs communication processing of the control unit 6. In this way, the current measuring device 1 and the communication I / F unit 8 perform data transmission / reception in both directions.

  FIG. 3 is a diagram showing the structure of the current transformer 3 configured in an open magnetic circuit and an overview of the current measuring device 1. The current measuring device 1 has a structure in which the current measuring device 1 is installed in a terminal portion of the current limiter 9. The current transformer 3 has a structure in which the core sandwiches the L1 and L2 wires excluding the neutral wire N connection terminal.

  FIG. 8 is a view showing the structure of the current transformer 3 configured in a closed magnetic circuit and an overview of the current measuring device 1. The current measuring device 1 has a structure in which the current measuring device 1 is installed in a terminal portion of the current limiter 9. The current transformer 3 has a structure in which the core sandwiches the L1 and L2 wires excluding the neutral wire N connection terminal. A magnetic material 13 similar to the core is disposed below the clamp 12 for fitting, and a closed magnetic circuit is formed by the core material of the current transformer 3 and the magnetic material 13 of the clamp 12 at the time of fitting.

  The current measuring device 1 configured as described above is arranged at the terminal portion of the current limiter 9 as shown in FIGS. 8 and 9 and is connected to the L1-N and L2-N phases of the electric circuit 2 respectively. The measured value is transmitted to the measurement controller 10 via the communication I / F unit 8 to measure the current. When the current measuring device 1 is installed in the current limiter 9 and the communication I / F unit 8 is attached as shown in FIG. 8, the AC power generated by the power transmission circuit 81 in the communication I / F unit 8 is generated by the power supply unit 7. A voltage is induced in the resonance coil 71. This is smoothed as shown in the above operation, stabilized by the regulator circuit 74, and power for operating each part in the current measuring device 1 is supplied. The measurement control unit 5 starts current measurement after reset by turning on the power. The start of current measurement may be started by a command from the measurement controller 10 (which constitutes the I / F unit) received via the communication I / F unit 8.

Next, the current measurement operation will be described. The current transformer 3 configured in an open magnetic circuit or a closed magnetic circuit measures the current flowing through L1 and L2, respectively, and the current detection unit 4 biases the output level of the transformer so that the BH curve shown in FIG. The current level ib is adjusted, and the voltage levels Vi1 (t) and Vi2 (t) and the bias current values ib1 (t) and ib2 (t) obtained from the line current IL for each of the L1 phase and the L2 phase are input to the measurement control unit 5. input. The measurement control unit 5 reads Vi1 (t), Vi2 (t) and bias currents ib1 (t), ib2 (t) that are proportional to the current amount, respectively, at predetermined time intervals using an AD converter or the like.
Next, the measurement control unit 5 calculates the current value I1 (t) of the L1 phase by subtracting ib1 (t) for the bias from Vi1 (t) as shown in the following equation.
I1 (t) = AVi1 (t) −ib1 (t)
However, A is a constant for converting the voltage value obtained by the line current IL into a current. Further, the measurement control unit 5 similarly calculates the current value I2 (t) of the L2 phase using the following equation.
I2 (t) = AVi2 (t) −ib2 (t)
However, A is a constant for converting the voltage value obtained by the line current IL into a current. Next, the measurement control unit 5 adds the current values I1 (t) and I2 (t) to calculate the total current IL. .
IL = I1 (t) + I2 (t)
In this way, the current value IL calculated by the measurement control unit 5 is sent from the measurement control unit 5 to the communication control unit 6 via SIO (serial I / O), and further, the communication circuit 76 in the communication control unit 6 is passed through. And transmitted to the communication circuit 86 of the communication I / F unit 8. The communication processing unit 86c that has received the current value IL transmits the current value IL to the measurement controller 10 via the communication medium conversion unit 86d, so that the measurement controller 10 can measure the current value.

In this way, the current measuring device 1 transmits the measurement data to the measurement controller 10 (I / F means) via the communication I / F unit 8 that is insulated in a non-contact manner. It can be installed, and the power for operation is supplied in a non-contact manner from the communication I / F unit 8 to generate a power source. Therefore, it is not necessary to separately wire the operation power source, and it is small and low cost. It becomes possible to realize a current measuring device that can be easily installed.
In addition, since the communication I / F unit 8 is also configured as a non-contact insulating structure, it is possible to perform safe construction without electric shock or the like.
In the present embodiment, the current value is calculated by the measurement control unit. However, the calculation algorithm is installed in the measurement controller 10, the measured source data is transmitted to the measurement controller, and the measurement controller 10 performs the necessary operation. You may comprise so that it may process into a measured value. Also. By configuring the calculation algorithm to be changeable from the measurement controller 10 and inputting it to the measurement control unit 5 via the communication control unit 6 and the communication I / F unit 8, the current value for each phase can be individually determined. It can be configured with the same configuration so that various measurement values such as measurement and measurement of average current can be output.
Although the current transformer is configured to fit into the terminal part of the current limiter, the same operation and similar effects can be achieved even if a separate structure using a split core or the like is used for the transformer part. Obtainable.

Embodiment 2. FIG.
The operation of the current measuring device according to Embodiment 2 of the present invention will be described. Since the configuration is the same as that of the first embodiment, description thereof is omitted. The current detection unit 4 according to the present embodiment is configured to detect harmonic components generated from the equipment in addition to the commercial frequency. Similarly, the current transformer 3 is configured to detect harmonic components generated from the equipment in addition to the commercial frequency.

  In the current measuring device 1 configured as described above, after the user or the installer confirms that there is no abnormality in the operation of the electric device 11 and the electric circuit 2, information indicating that the current measuring device 1 is normal from the measurement controller 10. Send. The measurement control unit 5 of the current measuring device 1 observes the harmonic signals of the L1-N and L2-N phases of the electric circuit 2 for a predetermined period, for example, about 2 to 3 days, and determines the characteristic amount of the harmonic pattern at the normal time. The harmonic information is recorded in a storage means (not shown) in the measurement control unit 5. In addition to the normal current measurement operation, the current measuring device 1 observes the harmonic signal of each phase of L1-N and L2-N, and compares the feature quantity recorded in the storage means with the observed harmonic signal. When different harmonic signals are detected, the information is reported to the measurement controller 10 via the communication control unit 6 and the communication I / F unit 8. The measurement controller 10 outputs a device deterioration alarm to the user as necessary. By reporting the aging deterioration of the device in this way, it becomes possible to use the electrical device safely.

Embodiment 3 FIG.
The operation of the current measuring device according to Embodiment 3 of the present invention will be described. Note that the configuration is the same as in the first and second embodiments, and a description thereof will be omitted. The current detection unit 4 according to the present embodiment is configured to detect harmonic components generated from the equipment in addition to the commercial frequency. Similarly, the current transformer 3 is configured to detect harmonic components generated from the equipment in addition to the commercial frequency.

  In the current measuring apparatus 1 configured as described above, the user or the installer observes harmonic signals of the L1-N and L2-N phases in addition to the normal current measuring operation, and stores them in the measurement control means 5. When a matching harmonic signal is detected by comparing the observed harmonic signal with a characteristic value such as a discharge from an outlet such as a corona discharge of the current circuit, or a discharge caused by deterioration of the connection part of the device. The information is reported to the measurement controller 10 via the communication control unit 6 and the communication I / F unit 8. The measurement controller 10 outputs an electric circuit deterioration alarm to the user as necessary. In this way, by notifying the aging deterioration of the electric circuit and the device connection part, the user can take measures corresponding to the aging deterioration such as repair, and the electric device can be used safely. In the above example, the feature amount is placed in the measurement control means 5 and abnormality is determined. However, a harmonic measurement signal is transmitted to the measurement controller 10 and the feature amount is included in the measurement controller 10. Even if it is configured to make a comparative judgment, the same operation and function can be realized, and the same effect can be obtained. Further, the measurement controller 12 has a feature amount, and the power measurement apparatus 1 may read the feature amount from the measurement controller 12 to the measurement control unit 5 through the communication unit 9 and then process the feature amount in the measurement control unit 5. A similar effect can be obtained.

  As an application example of the power measuring apparatus according to the present invention, there are a demand control system in household electrical appliances, an energy management system, an energy management of an equipment system such as a building / factory, and an energy saving control system.

It is a figure which shows the structural example of the current measuring device in Embodiment 1-3 of this invention. It is a figure which shows the structural example of the current detection coil in Embodiment 1-3 of this invention. It is a figure which shows the structural example of the current detection coil of the open magnetic circuit in Embodiment 1-3 of this invention. It is a figure which shows the structural example of the current detection coil of the closed magnetic circuit in Embodiment 1-3 of this invention. It is a figure which shows the example of a characteristic of the electric current detection part in Embodiment 1-3 of this invention. It is a figure which shows the circuit structural example of the power transmission circuit of the communication control part 6 and communication I / F part 8, and the power supply circuit 7 in Embodiment 1-3 of this invention. It is a figure which shows the circuit structural example of the communication circuit of the communication control part 6 and the communication I / F part 8 in Embodiment 1-3 of this invention. It is a figure which shows the example of installation of the electric current measurement apparatus in Embodiment 1-3 of this invention. It is a figure which shows the structural example of the measurement system containing the electric current measurement apparatus in Embodiment 1-3 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Current measuring device, 2 Electric circuit, 3 Current transformer, 4 Current detection part, 5 Measurement control part, 6 Communication control part, 7 Power supply part, 8 Communication I / F part, 9 Current limiter, 10 Measurement controller, 11 Electrical equipment , 12 clamp, 13 magnetic material, 71C capacitor, 71L coil, 72 diode, 73 smoothing circuit, 73a-b capacitor, 74 power regulator, 75 connector, 76 communication circuit, 76a transmission / reception resonance circuit, 76c microcomputer, 80 communication means (Communication I / F unit), 81 power transmission circuit, 84 excitation inverter, 84a to d switching element, 85 power transmission resonance circuit, 86 communication circuit, 86a transmission / reception resonance circuit, 86c control means, 86d communication medium conversion unit.

Claims (13)

A current detector for detecting the current in the electric circuit to which the electrical equipment is connected;
An arithmetic unit that calculates the current flowing through the electrical device based on the output of the current detector;
A power supply unit that receives power from a communication interface unit of an external measurement controller and generates an operating voltage of the arithmetic unit;
A current measurement device comprising: an external measurement controller; and a communication unit that performs communication of data signals such as measurement value data with a non-contact insulating structure via the communication interface unit.   The current measuring device according to claim 1, wherein the current detector is configured by at least one of a current transformer configured by an open magnetic circuit or a current transformer configured by a closed magnetic circuit.   The current measuring device according to claim 2, wherein the current transformer includes a load current detecting coil and a bias applying coil. A current measuring unit that converts the output of the current detector into a signal for input to the arithmetic unit;
The current measuring unit has a harmonic detection means for detecting a harmonic component of a commercial frequency or higher,
The arithmetic unit has a feature quantity of a high-frequency signal generated when the electric circuit is directly discharged, compares the output of the harmonic detection means and the feature quantity, and meets the predetermined requirement when the communication condition is met. The current measuring device according to claim 1, wherein an alarm signal for electric circuit deterioration is transmitted to an external measurement controller via the unit to prompt an alarm output. Instead of the calculation unit,
When the device has a characteristic amount of a high-frequency signal generated when the device is normal, the output of the harmonic detection means is compared with the feature amount, and when a predetermined requirement is met, an alarm signal of electric circuit deterioration via the communication unit The current measurement device according to claim 4, further comprising a calculation unit that transmits a current to the measurement controller.   The current measurement device according to claim 4 or 5, wherein the feature amount of the high-frequency signal is incorporated in advance in the calculation unit.   The current measurement device according to claim 4, wherein the feature amount of the high-frequency signal is read from the measurement controller to the calculation unit via the communication unit. An electric circuit breaker having a terminal part of the electric circuit, and a switch for switching and controlling connection and interruption of the electric circuit;
The current measuring device according to claim 1, wherein the current measuring device is attached to the electric circuit breaker by fitting the current detector to the terminal portion. The current measuring device according to any one of claims 1 to 8,
A communication interface unit,
The communication interface unit includes an AC power source that generates AC power and a first power transmission coil that transmits AC power from the AC power source by electromagnetic induction radio,
The power supply unit of the current measuring device includes a second power transmission coil that receives AC power by electromagnetic induction radio,
A current measurement system that transmits the AC power in a non-contact manner from the communication interface unit to the current measurement device via the first power transmission coil and the second power transmission coil. The current measuring device according to any one of claims 1 to 8,
A measurement controller, and a communication interface unit that communicates with the current measurement device,
The communication unit of the current measuring device includes a first coil that transmits a data signal by electromagnetic induction radio,
The communication I / F unit has a second coil for transmitting a data signal by electromagnetic induction radio,
The current measurement system characterized in that the measurement controller communicates data signals with the current measurement device via the first coil and the second coil in a non-contact manner.   The current measurement system according to claim 9 or 10, wherein the communication I / F unit includes a pair of wires.   The current measurement system according to claim 9, wherein the communication interface unit is configured by a LAN circuit with power supply such as power over IP.   The current measurement system according to claim 9 or 10, wherein the communication interface unit includes a USB circuit.

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