JP2003315388A - Phase adjusting device and power measuring device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase adjusting device and a power measuring device using the same, by configurating the phase adjusting device by mounting few new parts in the power measuring device and imparting versatility with no restriction in selecting an operation amplifier. <P>SOLUTION: This phase adjusting device comprises a current sensor 1 for detecting the input current I, a current transducer 3 for amplifying the output of the current sensor 1 to be processed by a circuit in a subsequent stage, a low-pass filter 5 comprising an elemental constant variable mechanism 5a assembled inside of the current transducer 3, a voltage sensor 2 for detecting the input voltage V, a voltage transducer 4 for amplifying the output of the voltage sensor 2 to be processed by the circuit in the subsequent stage, a low-pass filter 6 assembled inside of the voltage transducer 4, and a control means 7 for controlling the elemental constant variable mechanism 5a on the basis of the predetermined information indicating the phase difference between the output waveform of the current transducer 3 and the output waveform of the voltage transducer 4. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase adjusting device for easily adjusting a phase difference between an input current and an input voltage in a power measuring device and a power measuring device using the phase adjusting device.

[0002]

2. Description of the Related Art A power measuring device using a conventional phase adjusting device will be described with reference to FIGS. 13 (a) and 13 (b). The power measuring device X is a current measuring unit 100 that measures an input current.
And a voltage measuring unit 200 that measures an input voltage, and a power calculating unit 300 that calculates a power value from the measured values of the current measuring unit 100 and the voltage measuring unit 200 and outputs the result.

The current measuring unit 100 includes a current sensor 101.
And a current transducer 102 having a built-in low-pass filter 103. The current sensor 101 detects an input current as a waveform, the current transducer 102 amplifies the detected waveform to a signal level that can be handled by the power calculation unit 300, and the current transducer Unnecessary high frequency is cut by the low-pass filter 103 incorporated in the device 102.

The voltage measuring unit 200 includes a voltage sensor 201.
A voltage transducer 202 having a built-in low-pass filter 203 and a phase adjusting device 204. The voltage sensor 201 detects an input voltage as a waveform, and the voltage transducer 202 detects a detected waveform up to a signal level that the power calculation unit 300 can handle. The low-pass filter 103 built in the voltage transducer 202 cuts unnecessary high frequencies, and the phase adjuster 204 delays the time generated by the current measuring unit 100 and the time generated by the voltage measuring unit 200 as described later. Adjust so that the delay is equal.

The power calculation unit 300 multiplies the output value of the current measuring unit 100 and the output value of the voltage measuring unit 200,
The result is output as a power value in a pulse train or the like.

Here, the phase adjusting device 204 will be further described. The phase adjusting device 204 includes the current measuring unit 100.
The purpose is to eliminate the measurement power error caused by the difference between the time delays, which is caused by the difference between the time delays generated by the voltage measurement unit 200 and the time delays generated by 1. That the time delay generated by the current measuring unit 100 and the time delay generated by the voltage measuring unit 200 are equal to each other means that the phase difference between the input voltage and the input current (which may be read as a time difference) is maintained, That is, the similar waveforms are input to the power calculation unit 300.

For example, when the load power factor is 1, the phase difference (time difference) between the input voltage and the input current is zero, so that the phase difference (time difference) between the similar waveforms input to the power calculator 300 is equal to each other. The phase adjusting device 204 adjusts so as to be zero. The adjustment method is performed by delaying or advancing either one of the voltage waveform and the current waveform with respect to time.

An example of such a phase adjusting device is disclosed in Japanese Patent Laid-Open No. 2000-74961. As shown in FIG. 13B, the phase adjusting device Y includes operational amplifiers OP100 and OP200 and a resistor R10.
0 to R400 and a variable resistor R500. The non-inverting input terminal of the operational amplifier OP100 receives the voltage waveform amplified by the amplifier (not shown) installed in the previous stage. The output of the operational amplifier OP100 is the operational amplifier OP2.
00 into the non-inverting input terminal. The output of the operational amplifier OP200 is connected to one end of the resistor R300 and one end of the resistor R100, and is also connected to a circuit (not shown) in the subsequent stage as the output of the phase adjusting device Y. The other end of the resistor R300 is connected to one end of the variable resistor R500 and also to the inverting input terminal of the operational amplifier OP200. The other end of the variable resistor R500 is connected to one end of the resistor R400, and the other end of the resistor R400 is connected to a common potential. The other end of the resistor R100 is connected to one end of the resistor R200 and also to the inverting input terminal of the operational amplifier OP100. The other end of the resistor R200 is connected to the common potential.

The phase adjusting device Y constructed as described above.
Changes the feedback gain of the operational amplifier OP200 according to the value of the variable resistor R500,
The phase is adjusted by adjusting the amplification degree of 200.

[0010]

However, in the case of the phase adjusting device as described above, the phase adjusting device Y is added to the power measuring device X. Therefore, for example, in the case of the phase adjusting device Y described above, calculation is performed. There is a problem that two amplifiers, four fixed resistors and one variable resistor increase.

Further, the method of constructing the phase adjusting device with the operational amplifier and the resistor is designed because the capacitance required for the time constant (delay element) depends on the internal capacitance of the operational amplifier. There is a problem in that the method cannot be said to be versatile because the upper operational amplifier is limited in selection.

The present invention has been made in view of the above problems, and an object of the present invention is to provide almost no new parts in the power measuring device and to limit the selection of operational amplifiers. Configure a phase adjuster with no versatility,
An object of the present invention is to provide a phase adjusting device and a power measuring device using the phase adjusting device.

[0013]

In order to achieve the above object, the invention of claim 1 is a current sensor for detecting an input current, and a current transducer for amplifying the output of the current sensor so that a circuit in a subsequent stage can handle it. A voltage sensor that detects an input voltage, a voltage transducer that amplifies the output of the voltage sensor so that a circuit in a subsequent stage can handle it, a low-pass filter that either the current transducer or the voltage transducer has, and a low-pass filter A phase adjusting device comprising an element constant variable mechanism for changing the element constant and control means for automatically controlling the element constant variable mechanism based on predetermined information indicating a phase difference between the output waveform of the current transducer and the output waveform of the voltage transducer. And

According to a second aspect of the present invention, in the first aspect of the present invention, the control means determines the time difference between the zero cross point of the output waveform of the current transducer and the zero cross point of the output waveform of the voltage transducer. As information, the element constant varying mechanism is controlled so as to reduce the time difference when the phase difference between the input current and the input voltage is zero.

According to a third aspect of the present invention, in the invention according to the first aspect, the control means has means for drawing a Lissajous figure from the output waveform of the current transducer and the output waveform of the voltage transducer, and the Lissajous figure. Is used as the predetermined information, and the element constant varying mechanism is controlled so that the Lissajous figure is drawn linearly when the phase difference between the input current and the input voltage is zero.

According to a fourth aspect of the present invention, in the invention according to the first aspect, the control means has means for drawing a Lissajous figure from the output waveform of the current transducer and the output waveform of the voltage transducer, and the Lissajous figure. Is the predetermined information, and when the phase difference between the input current and the input voltage is zero, the length of the line segment between two intersections between the Lissajous figure and one of the horizontal axis and the vertical axis is reduced to reduce the length. The constant variable mechanism is controlled.

According to a fifth aspect of the present invention, in the first aspect of the present invention, a temperature sensor is provided, and the control means sets the element constant variable mechanism based on control information having a temperature measured by the temperature sensor as a parameter. It was supposed to be controlled.

According to a sixth aspect of the present invention, in the first aspect of the present invention, there is provided means for measuring a frequency from an input current or an input voltage, and the control means is based on the control information having the frequency as a parameter. The element constant variable mechanism is controlled.

According to a seventh aspect of the invention, in the first aspect of the invention, the low-pass filter is a multiple feedback type, and the element constant variable mechanism is a feedback resistance of the low-pass filter.

According to an eighth aspect of the present invention, the phase adjusting device according to any one of the first to seventh aspects is built in, a power value is calculated from the output of the current transducer and the output of the voltage transducer, and the result is output. The electric power measuring device is provided with the electric power calculator.

According to a ninth aspect of the invention, in the eighth aspect of the invention, the control means is independent of the power measuring device and is an external device.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to Embodiments 1 to 4. (Embodiment 1) FIG. 1 shows the configuration of an electric power measuring device in which the phase adjusting device of the present embodiment is incorporated. This power measuring device A includes a current sensor 1 that detects an input current I, a current transducer 3 that amplifies an output of the current sensor 1 so that a circuit in a subsequent stage can handle it, and an element constant variable mechanism 5a incorporated in the current transducer 3. , A voltage sensor 2 that detects an input voltage V, a voltage transducer 4 that amplifies the output of the voltage sensor 2 so that a circuit in a subsequent stage can handle it, and a low-pass filter 6 that is incorporated in the voltage transducer 4. And a controller 7 for controlling the element constant variable mechanism 5a based on predetermined information indicating the phase difference between the output waveform of the current transducer 3 and the output waveform of the voltage transducer 4, and the output of the current transducer 3. The electric power value P is calculated from the output of the voltage transducer 4 and the result is output. An arithmetic unit 8.

Here, the current sensor 1 constituting the phase adjusting device, the current transducer 3, the voltage sensor 2,
Voltage transducer 4 and low pass filters 5 and 6
Is originally provided in the power measuring device A,
Further, since the control means 7 is realized as one function of the microcomputer or the like that constitutes the power calculation unit 8 of the power measuring apparatus A, the phase adjusting apparatus is configured without providing any new parts in the power measuring apparatus A. Has been done.

In this phase adjusting device, the element constant varying mechanism 5a provided in the low-pass filter 5 by the control means 7 is used.
Is automatically controlled, and the phase is adjusted by changing the feedback resistance value of the low-pass filter. Hereinafter, the low-pass filter 5, the element constant variable mechanism 5a, and the control means 7 will be described in detail.

FIG. 2 shows a circuit configuration of the low pass filter 5. The low-pass filter 5 includes a variable element constant mechanism 5a including feedback resistors R1a to R1c and an analog switch IC50, an operational amplifier OP1, and a resistor R.
2, R3 and capacitors C1 and C2. The non-inverting input terminal of the operational amplifier OP1 is connected to the common potential. One end of the resistor R3 and one end of the capacitor C1 are connected to the inverting input terminal of the operational amplifier OP1. The other end of the resistor R3 has a variable element constant mechanism 5a, a resistor R2, and a capacitor C.
The two ends are connected. The other end of the variable element constant mechanism 5a is connected to the other end of the capacitor C1 and the output of the operational amplifier OP1, and is also connected to the subsequent circuit as the output of the low pass filter 5. The other end of the resistor R2 is connected to the previous circuit as an input of the low pass filter 5. The other end of the capacitor C2 is connected to the common potential.

As shown in FIG. 3, the low-pass filter 5 is included in the current transducer 3 and the voltage transducer 4 as a matter of course, and cuts off the high frequency noise of the circuit in the preceding stage and the anti-aliasing of the digital power calculator. The feedback resistor R10 of the general low-pass filter 5'which is installed for the purpose is replaced by the element constant variable mechanism 5a. Like the low-pass filter 5 ′, this type of filter that is fed back from the output end of the operational amplifier OP10 to the input end of the operational amplifier OP10 via a resistor and a capacitor is called a multiple feedback type, and is generally a filter due to an error of components. It is said that there is little deviation in characteristics, and there is little deviation in filter characteristics due to changes in temperature and aging.

In the element constant variable mechanism 5a, the feedback resistors R1a to R1c are analog switch ICs 50, respectively.
Are connected in parallel via the element constant variable mechanism 5a.
The resistance value of is the analog switch IC whose ON is controlled.
It is a parallel value of the feedback resistors R1a to R1c connected to 50. For example, feedback resistors R1a and R1b
When the analog switch IC50 connected to is controlled to be ON, and the analog switch IC50 connected to the feedback resistor R1c is controlled to be turned OFF, the resistance value of the element constant variable mechanism 5a becomes the feedback resistances R1a and R1.
It is a parallel value with b. The analog switch IC 50 is ON / OFF controlled by the control means 7.

FIG. 4 shows an example of the difference between the resistance value of the variable element constant mechanism 5a and the input / output time of the low pass filter 5. Since the time constant of the low-pass filter 5 is determined by the product of the resistance value of the element constant variable mechanism 5a and the capacitor C1, when the resistance value of the element constant variable mechanism 5a becomes large, the time constant becomes large and the input / output of the low-pass filter 5 becomes large. The time difference becomes large. On the other hand, when the resistance value of the variable element constant mechanism 5a becomes small, the time constant becomes small and the input / output time difference of the low pass filter 5 becomes small.

The control means 7 is an analog switch IC50.
Of the feedback resistors R1a to R1c connected to the ON-controlled analog switch IC50.
The resistance value of the element constant variable mechanism 5a is changed by changing the combination of. Then, by utilizing the relationship between the resistance value of the variable element constant mechanism 5a and the input / output time difference of the low pass filter 5 in FIG. 4, the input / output time difference of the low pass filter 5 is changed by changing the resistance value of the variable element constant mechanism 5a. Change
The phase of the output waveform of the current transducer 3 is adjusted.

Next, the phase adjusting procedure of the phase adjusting device configured as described above will be described with reference to the flowchart of FIG. The phase difference between the input current I and the input voltage V is known.

First, the input current I and the input voltage V are read by the current sensor 1 and the voltage sensor 2 (step S).
1). After the input current I is amplified by the current transducer 3 and passed through the low pass filter 5, the output waveform I ′ is input to the control means 7, and similarly, the input voltage V is amplified by the voltage transducer 4 and passed through the low pass filter 6. The output waveform V'of is input to the control means 7 (step S2).

The control means 7 controls the output waveform I'of the current transducer 3 and the output waveform V'of the voltage transducer 4.
(The phase of the output waveform I ′ of the current transducer 3 minus the phase of the output waveform V ′ of the voltage transducer 4) is the phase difference between the input current I and the input voltage V (input from the phase of the input current I If the output waveform I ′ of the current transducer 3 lags behind the output waveform V ′ of the voltage transducer 4, the element constant variable mechanism 5
An ON / OFF control signal is sent to the analog switch IC 50 of the element constant variable mechanism 5a so as to reduce the resistance value of a (advance) (step S5). When the phase difference between the output waveform I ′ of the current transducer 3 and the output waveform V ′ of the voltage transducer 4 is smaller than the phase difference between the input current I and the input voltage V (steps S3 and S4), the output waveform I ′ of the current transducer 3 Is ahead of the output waveform V ′ of the voltage transducer 4, the element constant variable mechanism 5
An ON / OFF control signal is sent to the analog switch IC 50 so as to increase the resistance value of a (phase delay) (step S6).

The analog switch IC 50 is turned on / off according to a control signal, and feedback resistors R1a to R1 are connected to the ON-controlled analog switch IC50.
The combination of c increases or decreases the resistance value of the variable element constant mechanism 5a, and the output waveform I'of the current transducer 3 is delayed or advanced accordingly.

The above operation is repeated until the phase difference between the input current I and the input voltage V and the phase difference between the output waveform I'of the current transducer 3 and the output waveform V'of the voltage transducer 4 become the same in step S3. .

In the above-mentioned phase adjustment procedure, the time difference between the zero cross points of each waveform may be used as the information indicating the phase difference of each waveform.

In the flowchart of FIG. 6, when the phase difference between the input current I and the input voltage V is zero, the time difference between the zero cross points of the output waveform I'of the current transducer 3 and the output waveform V'of the voltage transducer 4 is used. A procedure for controlling the element constant variable mechanism 5a to adjust the phase so that the time difference is reduced will be described.

First, the input current I and the input voltage V are read by the current sensor 1 and the voltage sensor 2 (step S1).
0). After the input current I is amplified by the current transducer 3 and passed through the low pass filter 5, the output waveform I ′ is input to the control means 7, and similarly, the input voltage V is amplified by the voltage transducer 4 and passed through the low pass filter 6. The output waveform V'of is input to the control means 7 (step S11).

The control means 7 obtains the zero crossing point time t1 of the output waveform I'of the current transducer 3 (step S
12) Similarly, the zero crossing point time t2 of the output waveform V ′ of the voltage transducer 4 is obtained (step S13),
The zero-cross point time difference (= t1−t2) is obtained from these values (step S14).

The absolute value of the zero-cross point time difference is greater than the target value (for example, zero) (step S15), and the zero-cross point time t of the output waveform I'of the current transducer 3 is t.
When 1 is later than the zero cross point time t2 of the output waveform V ′ of the voltage transducer 4 (step S16), the control means 7 delays the output waveform I ′ of the current transducer 3 after the output waveform V ′ of the voltage transducer 4. The analog switch IC 50 is turned on / off so that the resistance value of the element constant variable mechanism 5a is reduced (advanced).
Is sent (step S17). The time t1 of the zero crossing point of the output waveform I ′ of the current transducer 3 is the time t2 of the zero crossing point of the output waveform V ′ of the voltage transducer 4.
At an earlier time (step S16), the control means 7 determines that the output waveform I ′ of the current transducer 3 is ahead of the output waveform V ′ of the voltage transducer 4, and increases the resistance value of the element constant variable mechanism 5a (delayed). Phase), an ON / OFF control signal is sent to the analog switch IC 50 (step S18).

The analog switch IC 50 is turned on / off in response to a control signal, and feedback resistors R1a to R1 are connected to the ON-controlled analog switch IC50.
The combination of c increases or decreases the resistance value of the variable element constant mechanism 5a, and the output waveform I'of the current transducer 3 is delayed or advanced accordingly.

The above operation is repeated in step 15 until the absolute value of the zero crossing point time difference becomes equal to or less than the target value.

As described above, the phase adjustment of the power measuring apparatus A can be easily performed only by making the feedback resistance of the low-pass filter variable by using the low-pass filter which is naturally included in the current transducer 3 and the voltage transducer 4. Functions can be added.

In this embodiment, the low-pass filter 5 incorporated in the current transducer 3 is provided with the variable element constant mechanism 5a, but the low-pass filter 6 incorporated in the voltage transducer 4 is used.
An element constant variable mechanism may be provided in the.

The control means 7 may be an external device independent of the power measuring device A, instead of being incorporated in the power measuring device A as one function of the microcomputer constituting the power calculating part 8. Specifically, the output waveform I ′ of the current transducer 3 and the output waveform V ′ of the voltage transducer 4 are connected to an external device in which the control means 7 is incorporated by a connector connection or the like, and a phase adjustment procedure is performed. A control signal is transmitted to the element constant variable mechanism 5a of the measuring device A by connecting a connector or the like. By using the control means 7 as an external device, the calculation processing load of the power measuring device A can be reduced.

(Embodiment 2) Since the basic configuration of this embodiment is the same as that of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted. Only the characteristic parts of this embodiment will be described. The details will be described.

That is, this embodiment is different from the first embodiment in that
The control means 7 outputs the output waveform I ′ of the current transducer 3.
And the output waveform V ′ of the voltage transducer 4 have a function of drawing a Lissajous figure (not shown), and the Lissajous figure is used as information indicating the phase difference between the respective waveforms for phase adjustment. There is.

The Lissajous figure drawn from the output waveform I'of the current transducer 3 and the output waveform V'of the voltage transducer 4 is linear when the phase difference between the two output waveforms I'and V'is zero. Become. Therefore, when the phase difference between the input current I and the input voltage V is zero, if the Lissajous figure drawn by the output waveforms I ′ and V ′ of the current transducer 3 and the voltage transducer 4 is controlled so as to approach a straight line, the input The target phase adjustment can be performed by approaching the phase difference (= zero) between the current I and the input voltage V.

In the flow chart of FIG. 7, when the phase difference between the input current I and the input voltage V is zero, a Lissajous figure drawn from the output waveform I ′ of the current transducer 3 and the output waveform V ′ of the voltage transducer 4 is used. A procedure for adjusting the phase will be described.

First, the current sensor 1 and the voltage sensor 2 read the input current I and the input voltage V (step S20). After the input current I is amplified by the current transducer 3 and passed through the low pass filter 5, the output waveform I ′ is input to the control means 7, and similarly, the input voltage V is amplified by the voltage transducer 4 and passed through the low pass filter 6. Output waveform V'of
Input to the control means 7 (step S21).

The control means 7 controls the output waveform I'of the current transducer 3 and the output waveform V'of the voltage transducer 4.
A Lissajous figure is created from the above (step S22), and the length of a line segment L (not shown) between two intersections of the created Lissajous figure and the x-axis is obtained (step S23).

When the length of the line segment L between the two intersections is not less than the predetermined target value (step S24), the resistance value of the variable element constant mechanism 5a is controlled as described later (step S25),
Until the length of the line segment L between the two intersections becomes equal to or less than a predetermined target value,
The above steps S20 to S25 are repeated.

When the length of the line segment L between the two intersections becomes equal to or less than the predetermined target value, the phase adjustment is completed.

Here, the control method in step S25 will be described in detail. First, the control means 7 causes the analog switch I to slightly increase the resistance value of the element constant variable mechanism 5a.
Send control signal to C50. Then, the process returns to step S20, a Lissajous figure is created again, and the length of the line segment L between the two intersections of the Lissajous figure and the x-axis is obtained. When the length of the line segment L between the two intersections is smaller than that of the previous time, a control signal is sent to the analog switch IC 50 so as to further increase the resistance value. Conversely, if the length of the line segment L between the two intersections increases,
The control signal is changed to the analog switch I so as to reduce the resistance value.
Send to C50.

As described above, in step S25, the control means 7 stores the previous value of the length of the line segment L between the two intersections, and the resistance value is increased so that the length of the line segment L between the two intersection points becomes longer. If it is smaller than the previous value, the resistance value is further increased, and conversely, if the resistance value is increased and the length of the line segment L between the two intersections is increased, the resistance value is decreased. Conversely, if the resistance value is decreased and the length of the line segment L between the two intersections is decreased, the resistance value is further decreased, and conversely, if it is increased, the resistance value is increased.

The step S24 may be read as if the Lissajous figure is drawn linearly. In other words,
When the length of the line segment L between the two intersections becomes equal to or less than a predetermined target value, the Lissajous figure is assumed to be linear, and the control means 7 sets the element constant variable mechanism 5 so that the Lissajous figure is linear.
The resistance value of a is controlled. FIG. 8 shows a flow chart when the Lissajous figure is controlled to be linear. That is, in the flowchart of FIG. 7, a line segment L between two intersections of the Lissajous figure and the x-axis is obtained (step S23),
It is determined whether the length of the line segment L is less than or equal to the target value (step S2
4) The step is replaced by step S26 for determining whether the Lissajous figure is linear.

Further, in this embodiment, the length of the line segment L between the two intersections of the Lissajous figure and the x-axis is obtained, and the line segment L between the two intersections is obtained.
Was controlled to be less than or equal to the target value, but based on the length of the line segment between the two intersections of the Lissajous figure and the y-axis, the length of the line segment was controlled to be less than or equal to the target value. You can go.

Further, also in this embodiment, the control means 7
May be an external device different from the power measuring device A without being incorporated in the power measuring device A.

(Embodiment 3) Since the basic configuration of this embodiment is the same as that of the first embodiment, the common parts are designated by the same reference numerals, and the description thereof will be omitted. Only the characteristic parts of this embodiment will be described. The details will be described.

FIG. 9 shows the configuration of a power measuring device B incorporating the phase adjusting device of this embodiment therein. This power measuring device B is different from the first embodiment in that it has a temperature sensor 9 and an E sensor.
EPROM (Electrically Erasable Programmable Rea
A non-volatile memory 10 such as a d-only memory) is added.

In the non-volatile memory 10, as a control information having the temperature measured by the temperature sensor 9 as a parameter, a table T in which optimum combinations of ON / OFF control values of the analog switch IC 50 are described for each predetermined temperature step is described.
(Not shown) is created in advance and stored. The method of creating the table T will be described later.

The control means 7 obtains the ambient temperature of the electric power measuring device B from the temperature sensor 9 and makes an optimum ON / O at that temperature.
The combination of the FF control values is read from the table T, and a control signal is sent to the analog switch IC 50 so that the combination becomes the combination.

As a result, the phase adjustment can be performed in real time with respect to the change in the ambient temperature, and the phase shift of the current / voltage sensor and the filter characteristic which is different depending on the temperature can be compensated, so that the temperature is less affected by the temperature change. A power measuring device with good characteristics can be provided.

Now, a method of creating the table T stored in the above-mentioned nonvolatile memory 10 will be described with reference to the flowchart of FIG. The procedure of this flow chart is performed in advance before using the power measuring apparatus B. The phase difference between the input current I and the input voltage V is known.

First, the ambient temperature of the power measuring device B is maintained at a constant value (step S30). The input current I and the input voltage V are read by the current sensor 1 and the voltage sensor 2 (step S31). The output waveform I ′ after the input current I is amplified by the current transducer 3 and passed through the low pass filter 5 is
The output waveform V'after being input to the control means 7, similarly amplified by the voltage transducer 4 by the voltage transducer 4 and passed through the low pass filter 6, is input to the control means 7 (step S3).
2).

The control means 7 adjusts the phase so that the phase difference between the input current I and the input voltage V and the phase difference between the output waveform I ′ of the current transducer 3 and the output waveform V ′ of the voltage transducer 4 are the same. Perform (step S33). still,
As a method of phase adjustment, the method of reducing the time difference between the zero cross points described in the first embodiment or the method of using the Lissajous figure described in the second embodiment can be used. In that case, the phase difference between the input current I and the input voltage V is particularly zero.

When the phase difference between the input current I and the input voltage V and the phase difference between the output waveform I'of the current transducer 3 and the output waveform V'of the voltage transducer 4 become the same (step S34), the temperature data from the temperature sensor is detected. And the current control value after completion of the phase adjustment (O of the analog switch IC50
The N / OFF control value) is stored in the non-volatile memory 10 (step S35).

As a result, when the table T for each predetermined temperature step is completed (step S36), the table creation is terminated. When the table for each predetermined temperature step is not completed, the ambient temperature of the power measuring device B is changed by a predetermined temperature step within the operating temperature range of the power measuring device B (step S37), and the operation is repeated from step S30. .

The control means 7, the non-volatile memory 10 and the temperature sensor 9 may be external devices other than the power measuring device B.

(Embodiment 4) Since the basic configuration of this embodiment is the same as that of the first embodiment, the same parts are designated by the same reference numerals and the description thereof will be omitted. Only the characteristic parts of this embodiment will be described. The details will be described.

FIG. 11 shows the configuration of a power measuring device C incorporating the phase adjusting device of this embodiment therein. This power measuring device C is different from that of the first embodiment in that the EEPROM (El
ectrically Erasable Programmable Read-Only Memor
The configuration is such that a nonvolatile memory 10 such as y) is added.

In the non-volatile memory 10, as control information having the frequency of the input current I or the input voltage V as a parameter, the optimum analog switch IC 50 for each frequency (50 Hz or 60 Hz) of the input current I or the input voltage V is selected. Table T showing combinations of ON / OFF control values
(Not shown) is created in advance and stored. The method of creating the table T will be described later.

The control means 7 measures the use frequency from the A / D conversion value of the output waveform V ′ of the voltage transducer 4 and the like, reads out the optimum ON / OFF control value combination at the use frequency from the table T, A control signal is sent to the analog switch IC 50 so as to obtain the combination.

As a condition for using the power measuring device C, the input current I and the input voltage V are in phase with each other (= power factor 1) and the frequency is 50 Hz or 60 Hz.

As a result, the structure of the power measuring device having a common system frequency of 50/60 Hz can compensate for the phase shift of the current / voltage sensor and the filter characteristic, which are different depending on the used frequency, so that the power measuring device is less affected by the used frequency. can do.

A method of creating the table T stored in the above-mentioned nonvolatile memory 10 will be described with reference to the flowchart of FIG. The procedure of this flow chart is performed in advance before using the power measuring apparatus B.

First, the frequencies of the input current I and the input voltage V are maintained at 50 Hz (step S40). The input current I and the input voltage V are read by the current sensor 1 and the voltage sensor 2 (step S41). After the input current I is amplified by the current transducer 3 and passed through the low pass filter 5, the output waveform I ′ is input to the control means 7, and similarly, the input voltage V is amplified by the voltage transducer 4 and passed through the low pass filter 6. The output waveform V'of is input to the control means 7 (step S42).

The control means 7 adjusts the phase so that the phase difference between the input current I and the input voltage V and the phase difference between the output waveform I ′ of the current transducer 3 and the output waveform V ′ of the voltage transducer 4 become the same. Perform (step S43). still,
As a method of phase adjustment, the method of reducing the time difference between the zero cross points described in the first embodiment or the method of using the Lissajous figure described in the second embodiment can be used.

When the phase difference between the input current I and the input voltage V and the phase difference between the output waveform I'of the current transducer 3 and the output waveform V'of the voltage transducer 4 become the same (step S44), the current frequency and phase adjustment are performed. The current control value after completion (ON / OFF control value of the analog switch IC 50) is stored in the nonvolatile memory 10 (step S4).
5).

As a result, when the table T has been created (step S46), the table creation is terminated. When the table is incomplete, the frequencies of the input current I and the input voltage V are changed to 60 Hz and maintained (step S47), and the operation is repeated from step S41.

The control means 7 and the non-volatile memory 10
May be an external device different from the power measuring device C.

[0081]

According to the invention of claim 1, a current sensor for detecting an input current, a current transducer for amplifying an output of the current sensor so that a circuit in a subsequent stage can handle it, a voltage sensor for detecting an input voltage, and a subsequent stage A voltage transducer that amplifies the output of the voltage sensor so that the circuit can handle, a low-pass filter included in either the current transducer or the voltage transducer, an element constant variable mechanism that changes an element constant of the low-pass filter, and the current Since the phase adjusting device comprises a control means for automatically controlling the element constant varying mechanism based on predetermined information indicating the phase difference between the output waveform of the transducer and the output waveform of the voltage transducer, the phase adjusting device is provided in the power measuring device. If you do, many parts can be shared with the power measuring device,
There is an effect that it is possible to configure a power measuring device provided with a phase adjusting device without providing any new components.

According to a second aspect of the present invention, in the first aspect of the invention, the control means sets the time difference between the zero cross point of the output waveform of the current transducer and the zero cross point of the output waveform of the voltage transducer to the predetermined value. As information, when the phase difference between the input current and the input voltage is zero, the element constant variable mechanism is controlled so as to reduce the time difference, so that the phase adjustment is performed when the phase difference between the input current and the input voltage is zero. This is performed automatically, and has the effect that the phase can be adjusted in real time with higher accuracy than when the phase is adjusted manually.

According to a third aspect of the present invention, in the invention according to the first aspect, the control means has means for drawing a Lissajous figure from the output waveform of the current transducer and the output waveform of the voltage transducer. Is used as the predetermined information, and when the phase difference between the input current and the input voltage is zero, the variable element constant mechanism is controlled so that the Lissajous figure is drawn linearly. Therefore, as in the invention of claim 2, When the phase difference between the input current and the input voltage is zero,
The phase adjustment is performed automatically, and the effect is that it is possible to perform the adjustment in real time with higher accuracy than when performing the phase adjustment manually.

According to a fourth aspect of the present invention, in the invention according to the first aspect, the control means has means for drawing a Lissajous figure from the output waveform of the current transducer and the output waveform of the voltage transducer. Is the predetermined information, and when the phase difference between the input current and the input voltage is zero, the length of the line segment between two intersections between the Lissajous figure and one of the horizontal axis and the vertical axis is reduced to reduce the length. Since the constant variable mechanism is controlled, the method according to claim 2 or 3
Similarly to the invention of (1), when the phase difference between the input current and the input voltage is zero, the phase adjustment is automatically performed, and there is an effect that the adjustment can be performed in real time more accurately than the manual phase adjustment.

According to a fifth aspect of the present invention, in the first aspect of the present invention, a temperature sensor is provided, and the control means sets the element constant variable mechanism based on control information having a temperature measured by the temperature sensor as a parameter. Since the control is performed, it is possible to perform the phase adjustment in real time with respect to the change in the ambient temperature, and it is possible to compensate for the phase shift of the current / voltage sensor and the filter characteristic that differ depending on the temperature.

According to a sixth aspect of the present invention, in the first aspect of the invention, there is provided means for measuring a frequency from an input current or an input voltage, and the control means is based on control information having the frequency as a parameter. Since the variable element constant mechanism is controlled, the structure of the power measuring device is common to the system frequency of 50/60 Hz.
There is an effect that the phase shift of the filter characteristic can be compensated.

According to a seventh aspect of the present invention, in the first aspect of the invention, the low-pass filter is a multiple feedback type, and the element constant variable mechanism is a feedback resistance of the low-pass filter. There is an effect that it is possible to configure the device, and it is possible to configure the phase adjusting device having the feature that the deviation of the filter characteristics with respect to the temperature / aging change of the multiple feedback filter is small.

According to an eighth aspect of the present invention, the phase adjusting device according to any one of the first to seventh aspects is built in, a power value is calculated from the output of the current transducer and the output of the voltage transducer, and the result is output. Since it is provided with a power calculation unit that operates, there is an effect that a power measurement device having a built-in phase adjustment device can be configured.

According to a ninth aspect of the present invention, in the eighth aspect of the invention, the control means is independent of the power measuring device and is an external device. Therefore, the calculation processing load of the power measuring device can be reduced. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a power measuring device including a phase adjusting device according to a first embodiment.

FIG. 2 is a circuit diagram illustrating a low-pass filter of the above.

FIG. 3 is a circuit diagram illustrating a general low-pass filter of the above.

FIG. 4 is an explanatory diagram for explaining a resistance value of the element constant variable mechanism and an input / output time difference of the filter in the same.

FIG. 5 is a flowchart showing the concept of the above-mentioned phase adjustment.

FIG. 6 is a flowchart showing a procedure for phase adjustment in the above.

FIG. 7 is a flowchart showing a procedure of phase adjustment in the phase adjusting apparatus of the second embodiment.

FIG. 8 is a flowchart showing another phase adjustment procedure in the above.

FIG. 9 is a block diagram showing a configuration of a power measuring device including therein a phase adjusting device according to a third embodiment.

FIG. 10 is a flowchart showing a method of creating the above table.

FIG. 11 is a block diagram showing a configuration of a power measuring device including therein a phase adjusting device according to a fourth embodiment.

FIG. 12 is a flow chart showing a method of creating the above table.

FIG. 13 (a) is a block diagram showing a configuration of a power measuring device including a conventional phase adjusting device therein. (B) It is a circuit diagram explaining the conventional phase adjusting device.

[Explanation of symbols]

1 Current sensor 2 voltage sensor 3 Current transducer 4 voltage transducer 5 Low pass filter 5a Element constant variable mechanism 6 low pass filter 7 Control means 8 Power calculator A power measuring device I input current Output waveform of I'current transducer V input voltage Output voltage of V'voltage transducer

Claims (9)

[Claims] 1. A current sensor that detects an input current, a current transducer that amplifies an output of the current sensor so that a circuit in a subsequent stage can handle it, a voltage sensor that detects an input voltage, and a circuit in a subsequent stage that can handle the current sensor. A voltage transducer that amplifies the output of the voltage sensor, a low-pass filter that the current transducer or the voltage transducer has, an element constant variable mechanism that changes the element constant of the low-pass filter, the output waveform of the current transducer and the voltage A phase adjusting device comprising: a control means for automatically controlling the element constant varying mechanism based on predetermined information indicating a phase difference from an output waveform of the transducer. 2. The control means uses the time difference between the zero cross point of the output waveform of the current transducer and the zero cross point of the output waveform of the voltage transducer as the predetermined information, and determines the phase difference between the input current and the input voltage. 2. The phase adjusting device according to claim 1, wherein the element constant varying mechanism is controlled so as to reduce the time difference when it is zero. 3. The control means has means for drawing a Lissajous figure from the output waveform of the current transducer and the output waveform of the voltage transducer, and the Lissajous figure is the predetermined information, and the input current and the input voltage 2. The phase adjusting device according to claim 1, wherein the element constant varying mechanism is controlled so that the Lissajous figure is drawn linearly when the phase difference is zero. 4. The control means includes means for drawing a Lissajous figure from the output waveform of the current transducer and the output waveform of the voltage transducer, wherein the Lissajous figure is the predetermined information and the input current and the input voltage The element constant variable mechanism is controlled to reduce the length of a line segment between two intersections between the Lissajous figure and one of the horizontal axis and the vertical axis when the phase difference is zero. 1. The phase adjusting device according to 1. 5. A phase controller according to claim 1, further comprising a temperature sensor, wherein said control means controls said element constant variable mechanism based on control information having a temperature measured by said temperature sensor as a parameter. Adjustment device. 6. A device for measuring a frequency from an input current or an input voltage, wherein the control device controls the element constant variable mechanism based on control information having the frequency as a parameter. Item 2. The phase adjustment device according to item 1. 7. The phase adjusting device according to claim 1, wherein the low-pass filter is a multiple feedback type, and the element constant variable mechanism is a feedback resistor of the low-pass filter. 8. A power calculation unit that incorporates the phase adjusting device according to claim 1 and calculates a power value from the output of the current transducer and the output of the voltage transducer, and outputs the result. A power measuring device characterized by being provided. 9. The power measuring device according to claim 8, wherein the control means is independent of the power measuring device and is an external device.