JP5726658B2 - Measuring apparatus and measuring method - Google Patents

Description

  The present invention generates a reference physical quantity corresponding to a physical quantity of a measurement object by feedback control so that a difference from the physical quantity is reduced, and also measures a reference physical quantity or a converted physical quantity obtained by converting the reference physical quantity. The present invention relates to a measuring device and a measuring method for measuring a physical quantity of a body.

  As this type of measuring apparatus, the applicant of the present application has already proposed the measuring apparatus disclosed in Patent Document 1 below.

  This measuring apparatus generates a reference physical quantity (reference potential) corresponding to the physical quantity (voltage) of the measurement target object by feedback control so that a difference from the physical quantity is reduced, and calculates the physical quantity of the measurement target object based on the reference physical quantity. A measuring device for calculating, changing an amplification factor (gain) of feedback control, measuring a reference physical quantity before and after the change, and calculating a difference between the measured two reference physical quantities by either one of the two reference physical quantities A determination process for determining that the feedback control is defective when the calculated calculated value is equal to or greater than a predetermined reference value, and a determination process for determining that the feedback control is good when the calculated value is less than the reference value. Do at least one.

  In this measurement apparatus, by executing the above-described determination processing, it is possible to reliably recognize whether feedback control is good based on the determination result in the determination processing, and thereby, for example, the measurement is performed. Since it is possible to recognize whether the physical quantity of the measured object is reliable, it is possible to ensure the reliability of the physical quantity measurement of the measured object by the measuring apparatus.

JP 2009-162608 A (6th and 9th pages, FIG. 1)

  However, the above measuring apparatus has the following problems to be improved. In other words, since this measuring apparatus is configured to determine the quality of the feedback control by changing the amplification factor of the feedback loop, when the determination process is performed continuously, the reference physical quantity changes every time the amplification factor is changed. It fluctuates within the deviation of feedback control. Therefore, this measurement apparatus has a smooth waveform (for changing the amplification factor) when the waveform of the reference physical quantity is displayed as, for example, the waveform of the physical quantity of the measurement object on the monitor device due to the fluctuation of the reference physical quantity. There is a problem to be improved that it cannot be measured (observed) as a waveform in which the accompanying fluctuation does not occur.

  The present invention has been made to improve the above problems, and provides a measuring apparatus and a measuring method capable of measuring a physical quantity waveform of a measuring object as a smooth waveform while ensuring measurement reliability. The main purpose.

In order to achieve the above object, the measuring apparatus according to claim 1 generates a reference physical quantity corresponding to a physical quantity of a measurement object by feedback control so that a difference from the physical quantity is reduced, and based on the reference physical quantity. A measuring device for measuring the physical quantity of the measuring object,
In order to evaluate the gain of the feedback control, the gain is alternately switched between G and α × G (α is a positive number exceeding 1), and in the period in which the gain is G, the first order with respect to the reference physical quantity A primary correction process for adding the added physical quantity and outputting the result as a primary corrected reference physical quantity, and outputting the reference physical quantity as the primary corrected reference physical quantity as it is during the period in which the gain is α × G, and the primary added physical quantity Is multiplied by 1 / (α-1) to generate a secondary added physical quantity, and the secondary added physical quantity is added to the primary corrected reference physical quantity to generate an equivalent physical quantity equivalent to the physical quantity; Detecting the difference between the primary correction reference physical quantity when the gain is G and the primary correction reference physical quantity when the gain is α × G and so that the detected difference approaches zero. Physical quantity, before A primary addition physical quantity generation process for generating the primary addition physical quantity by attenuating one of the primary correction reference physical quantity and the equivalent physical quantity is executed.

  The measuring device according to claim 2 generates a reference physical quantity corresponding to the physical quantity of the measurement object by feedback control so that a difference from the physical quantity is reduced, and conversion obtained by converting the reference physical quantity A measuring apparatus for measuring the physical quantity of the measurement object based on a physical quantity, wherein the gain is set to G and α × G (α is a positive number exceeding 1) for evaluation of the gain of the feedback control. While the gain is G, a primary addition physical quantity is added to the conversion physical quantity and output as a primary correction conversion physical quantity while the gain is G, and the conversion physical quantity is used as it is in a period where the gain is α × G. A primary correction process that is output as the primary correction conversion physical quantity, and a secondary addition physical quantity is generated by multiplying the primary addition physical quantity by 1 / (α-1), and the secondary addition physical quantity is converted into the primary addition physical quantity. Conversion physical quantity generation processing for generating an equivalent conversion physical quantity equivalent to the conversion physical quantity by adding to the positive conversion physical quantity, the primary correction conversion physical quantity when the gain is G, and the 1 when the gain is α × G The primary addition is performed by attenuating one of the conversion physical quantity, the primary correction conversion physical quantity, and the equivalent conversion physical quantity so that a difference from the next correction conversion physical quantity is detected and the detected difference approaches zero. A physical quantity that generates an equivalent physical quantity equivalent to the physical quantity by executing a primary addition physical quantity generation process for generating a physical quantity and a conversion reverse to the conversion from the reference physical quantity to the converted physical quantity on the equivalent converted physical quantity. Execute the generation process.

  The measuring device according to claim 3 is the measuring device according to claim 1 or 2, wherein when the physical quantity of the measurement object is an AC signal, a zero cross point detection process for detecting a zero cross point of the physical quantity is executed. The gain switching is executed in synchronization with the detected zero-cross point and at a cycle that is an integral multiple of the cycle of the physical quantity.

  According to a fourth aspect of the present invention, the reference physical quantity corresponding to the physical quantity of the measurement object is generated by feedback control so that the difference from the physical quantity is reduced, and the measurement object is based on the reference physical quantity. A measurement method for measuring the physical quantity, wherein the gain is switched between G and α × G (α is a positive number exceeding 1) alternately for evaluation of the gain of the feedback control. In the period G, a primary addition physical quantity is added to the reference physical quantity and output as a primary corrected reference physical quantity, and in the period where the gain is α × G, the reference physical quantity is directly output as the primary corrected reference physical quantity. And a primary addition physical quantity by multiplying the primary addition physical quantity by 1 / (α-1), and adding the secondary addition physical quantity to the primary correction reference physical quantity. A physical quantity generation process for generating an equivalent physical quantity equivalent to a physical quantity, and a difference between the primary correction reference physical quantity when the gain is G and the primary correction reference physical quantity when the gain is α × G are detected. And a primary addition physical quantity generation process for generating the primary addition physical quantity by attenuating one of the reference physical quantity, the primary correction reference physical quantity, and the equivalent physical quantity so that the detected difference approaches zero. Execute.

  According to a fifth aspect of the present invention, in the measurement method, the reference physical quantity corresponding to the physical quantity of the measurement object is generated by feedback control so that the difference from the physical quantity is reduced, and the conversion obtained by converting the reference physical quantity A measurement method for measuring the physical quantity of the measurement object based on a physical quantity, wherein the gain is set to G and α × G (α is a positive number exceeding 1) for evaluation of the gain of the feedback control. While the gain is G, a primary addition physical quantity is added to the conversion physical quantity and output as a primary correction conversion physical quantity while the gain is G, and the conversion physical quantity is used as it is in a period where the gain is α × G. A primary correction process that is output as the primary correction conversion physical quantity, and a secondary addition physical quantity is generated by multiplying the primary addition physical quantity by 1 / (α-1), and the secondary addition physical quantity is converted into the primary addition physical quantity. Conversion physical quantity generation processing for generating an equivalent conversion physical quantity equivalent to the conversion physical quantity by adding to the positive conversion physical quantity, the primary correction conversion physical quantity when the gain is G, and the 1 when the gain is α × G The primary addition is performed by attenuating one of the conversion physical quantity, the primary correction conversion physical quantity, and the equivalent conversion physical quantity so that a difference from the next correction conversion physical quantity is detected and the detected difference approaches zero. A physical quantity that generates an equivalent physical quantity equivalent to the physical quantity by executing a primary addition physical quantity generation process for generating a physical quantity and a conversion reverse to the conversion from the reference physical quantity to the converted physical quantity on the equivalent converted physical quantity. Execute the generation process.

  The measurement method according to claim 6 is the measurement method according to claim 4 or 5, wherein when the physical quantity of the measurement object is an AC signal, a zero cross point detection process for detecting a zero cross point of the physical quantity is executed. The gain switching is executed in synchronization with the detected zero-cross point and at a cycle that is an integral multiple of the cycle of the physical quantity.

  According to the measuring apparatus of claim 1 and the measuring method of claim 4, the reference physical quantity corresponding to the physical quantity of the measurement object is generated by feedback control so that the difference from the physical quantity is reduced, and When measuring the physical quantity of the measurement object based on this, even if this gain is alternately switched between G and α × G for the evaluation of the gain of the feedback control, the reference physical quantity is in the period where the gain is G. Correction processing for adding a primary addition physical quantity to the output and outputting it as a primary correction reference physical quantity, and outputting the reference physical quantity as a primary correction reference physical quantity as it is during a period in which the gain is α × G, and primary addition A physical quantity generation process for generating a secondary addition physical quantity by multiplying the physical quantity by 1 / (α-1) and generating an equivalent physical quantity equivalent to the physical quantity by adding the secondary addition physical quantity to the primary correction reference physical quantity; The difference between the primary correction reference physical quantity when the gain is G and the primary correction reference physical quantity when the gain is α × G is detected, and the reference physical quantity and primary correction are performed so that the detected difference approaches zero. An object to be measured by executing a gain evaluation process for a gain of feedback control by executing a primary addition physical quantity generation process for generating a primary addition physical quantity by attenuating one of a reference physical quantity and an equivalent physical quantity The waveform of the physical quantity can be measured as a smooth waveform (a waveform in which voltage fluctuation due to switching of the feedback control gain does not occur) while ensuring the reliability of the measurement of the physical quantity.

  In addition, according to the measuring apparatus according to claim 2 and the measuring method according to claim 5, the reference physical quantity corresponding to the physical quantity of the measurement object is generated by feedback control so that the difference from the physical quantity is reduced, and the reference is made. When measuring the physical quantity of the measurement object based on the converted physical quantity obtained by converting the physical quantity, the gain is alternately switched between G and α × G for the evaluation of the feedback control gain. In the period when the gain is G, the primary addition physical quantity is added to the conversion physical quantity and output as the primary correction conversion physical quantity, and the conversion physical quantity is output as it is as the primary correction conversion physical quantity during the period where the gain is α × G. Primary correction processing to be performed, the primary addition physical quantity is multiplied by 1 / (α-1) to generate a secondary addition physical quantity, and the secondary addition physical quantity is added to the primary correction conversion physical quantity to obtain a conversion physical quantity, etc. The difference between the conversion physical quantity generation process for generating the equivalent equivalent conversion physical quantity and the primary correction conversion physical quantity when the gain is G and the primary correction conversion physical quantity when the gain is α × G and the detected difference are A primary addition physical quantity generation process for generating a primary addition physical quantity by attenuating any one of a conversion physical quantity, a primary correction conversion physical quantity, and an equivalent conversion physical quantity so as to approach zero, and conversion from a reference physical quantity to a conversion physical quantity Execute the gain evaluation process for the feedback control gain by executing the inverse conversion to the equivalent conversion physical quantity and executing the physical quantity generation process that generates the equivalent physical quantity equivalent to the physical quantity as the reference physical quantity. The waveform of the physical quantity flowing through the measurement object can be measured as a smooth waveform while ensuring measurement reliability.

  Further, according to the measuring device according to claim 3 and the measuring method according to claim 6, since the switching timing of the gain G, α × G of the feedback loop is synchronized with the period of the equivalent physical quantity or equivalent converted physical quantity, The superimposition of switching noise on the equivalent physical quantity and equivalent conversion physical quantity due to the switching of the gain G and α × G of the feedback loop can be greatly reduced.

It is a lineblock diagram of voltage measuring devices 1 and 1A. FIG. 2 is a circuit diagram of a current-voltage conversion unit CV in FIG. 1. 3 is a configuration diagram of a voltage generation unit 34. FIG. FIG. 6 is a waveform diagram for explaining the operation of the voltage measuring device 1. FIG. 6 is another waveform diagram (waveform diagram in a state where the switching signal S1 is asynchronous) for explaining the operation of the voltage measuring apparatus 1; 2 is a configuration diagram of a current measuring device 51. FIG. It is a model figure of the current measurement part 52 of FIG. FIG. 6 is another waveform diagram for explaining the operation of the voltage measuring apparatus 1. It is a principal part block diagram for demonstrating the structure which processes each component enclosed with the dashed-dotted line in the voltage measuring device 1 with software.

  Hereinafter, embodiments of a measurement apparatus and a measurement method will be described with reference to the accompanying drawings.

  First, a voltage measuring device will be described as an example.

  As shown in FIG. 1, the voltage measurement device 1 includes a voltage measurement unit 2 and a deviation correction unit 3, and is configured to be able to measure an AC voltage V <b> 1 (an example of a physical quantity) of the measurement object 4 without contact.

  As shown in FIG. 1, the voltage measurement unit 2 includes a floating circuit unit 11 and a first main body circuit unit 12, and detects an AC voltage V <b> 1 (detection target AC voltage) generated in the measurement object 4 in a non-contact manner ( It is configured as a non-contact type voltage measurement unit capable of measurement).

  As shown in FIG. 1, the floating circuit unit 11 includes a guard electrode 21, a detection electrode 22, a current-voltage conversion unit CV, a drive circuit 25, and an insulation circuit 26, and constitutes a probe unit PU as an example. In this example, the current-voltage conversion unit CV includes a current-voltage conversion circuit 23 and an integration circuit 24 as illustrated in FIG. In this example, the insulating circuit 26 includes a photocoupler (hereinafter also referred to as “photocoupler 26”) as an example.

  The guard electrode 21 is formed in a box shape using a conductive material (for example, a metal material), and is configured as an internal ground in the floating circuit unit 11. In addition, as an example, the guard electrode 21 contains a detection electrode 22, a current-voltage conversion circuit 23, an integration circuit 24, a drive circuit 25, and a photocoupler 26. Thus, the configuration from the current-voltage conversion circuit 23 to the photocoupler 26 is covered with the guard electrode 21.

  In addition, the guard electrode 21 has an opening (hole) 21a. In this example, the entire guard electrode 21 including the opening 21a is an insulating layer (not shown) formed of a synthetic resin material. Covered. The detection electrode 22 is formed in a flat plate shape, for example, and is disposed at a position facing the opening 21 a in the guard electrode 21.

  As an example, as shown in FIG. 2, the current-voltage conversion circuit 23 has a non-inverting input terminal connected to the guard electrode 21 via a resistor 23a, an inverting input terminal connected to the detection electrode 22, and a resistor 23b. Is provided with a first operational amplifier 23c connected between an inverting input terminal and an output terminal as a feedback circuit. In the current-voltage conversion circuit 23, the first operational amplifier 23c operates by receiving supply of a positive voltage Vf + and a negative voltage Vf−, which will be described later, and the AC voltage V1 of the measurement object 4 and the voltage of the guard electrode 21 (described later). Due to the potential difference Vdi with respect to the reference voltage V4), a current value corresponding to the potential difference Vdi is used between the measurement object 4 and the detection electrode 22 (specifically, a path including the detection electrode 22 and the resistor 23b). A detection current (hereinafter also referred to as a current signal) I flowing in the signal is converted into a detection voltage V2 and output. In this case, the amplitude of the detection voltage V2 changes in proportion to the amplitude of the current signal I.

  For example, as shown in FIG. 2, the integrating circuit 24 has a non-inverting input terminal connected to the guard electrode 21 via a resistor 24a and an inverting input terminal connected to the first operational amplifier 23c via an input resistor 24b. The second operational amplifier 24d is connected to the output terminal and the capacitor 24c is connected between the inverting input terminal and the output terminal as a feedback circuit. In the integration circuit 24, the second operational amplifier 24d operates by receiving the supply of the positive voltage Vf + and the negative voltage Vf−, and integrates the detection voltage V2, whereby the AC voltage V1 of the measuring object 4 and the guard electrode 21 are integrated. An integrated voltage V3 whose voltage value changes in proportion to the potential difference Vdi with respect to the above voltage is generated and output.

  As shown in FIG. 1, the drive circuit 25 is arranged with the photocoupler 26 at the subsequent stage of the integration circuit 24, that is, between the integration circuit 24 of the current-voltage conversion unit CV and the voltage generation unit 34. For example, the drive circuit 25 has a base terminal connected to the output terminal of the second operational amplifier 24d via the input resistor 25a, a collector terminal connected to the photocoupler 26, and an emitter terminal connected to the negative voltage Vf−. Transistor (in this example, as an example, an NPN bipolar transistor) 25b. The light emitting diode as the primary circuit of the photocoupler 26 has a cathode terminal connected to the collector terminal of the transistor 25b and an anode terminal connected to the positive voltage Vf +. The phototransistor as the secondary circuit of the photocoupler 26 is connected to the first main body circuit unit 12 through the wiring W1.

  With this configuration, when the photocoupler 26 is driven by the drive circuit 25 and operates in the linear region, the resistance value of the phototransistor in the photocoupler 26 changes according to the voltage value of the integrated voltage V3 (substantially in proportion). . Therefore, the photocoupler 26 is electrically insulated from the integration voltage V3 from the integration voltage V3, which is an analog signal input from the integration circuit 24 in combination with a resistor 33 (described later) of the first main body circuit unit 12. It is converted into an integrated voltage V3a which is a new analog signal.

  As shown in FIG. 1, the first main body circuit unit 12 includes, as an example, a main power supply unit 31, a DC / DC converter (hereinafter also simply referred to as “converter”) 32, a current / voltage conversion resistor 33, and a voltage generation unit. 34, a gain switching signal generation unit 35, a processing unit 36, and a display unit 17. The first body circuit unit 12 constitutes a body circuit unit (main unit) MU together with the deviation correction unit 3 as the second body circuit unit, and is connected to the probe unit PU via the wiring W1 as described above. .

  The main power supply unit 31 includes, for example, a battery, and operates each component 32, 34, 35, 36, 37 of the first body circuit unit 12 and each component described later of the deviation correction unit 3. A positive voltage Vdd and a negative voltage Vss (DC voltages having the same absolute value generated with reference to the potential of the ground G1 and having different polarities) are generated from the DC voltage of the battery and output.

  For example, the converter 32 includes an insulated transformer having a primary winding and a secondary winding that are electrically insulated from each other, a drive circuit that drives the primary winding of the transformer, and a secondary winding of the transformer. A DC conversion unit (both not shown) that rectifies and smoothes the induced AC voltage is provided, and is configured as an insulated power source in which the secondary side is electrically insulated from the primary side. In this converter 32, the drive circuit operates based on the input positive voltage Vdd and negative voltage Vss, and drives the primary winding of the transformer in a state where the positive voltage Vdd is applied to the secondary winding with an AC voltage. Induces. The direct current converter rectifies and smoothes the alternating voltage. Thereby, the voltage (positive voltage Vf + and negative voltage Vf−) is electrically separated from the floating state (ground G1, positive voltage Vdd and negative voltage Vss) with reference to the voltage of the guard electrode 21 (voltage of the internal ground). Generated). The positive voltage Vf + and the negative voltage Vf− generated in this way are supplied to the floating circuit unit 11 in a state where the internal ground is electrically connected to the guard electrode 21. The positive voltage Vf + and the negative voltage Vf− are generated as direct current voltages having substantially the same absolute value and different polarities.

  The resistor 33 has one end connected to the positive voltage Vdd and the other end connected to the collector terminal of the phototransistor in the photocoupler 26. As a result, the resistor 33 and the phototransistor are connected in series between the positive voltage Vdd and the negative voltage Vss. For this reason, when the resistance value of the phototransistor changes according to the voltage value of the integrated voltage V3, the potential difference (Vdd−Vss) between the positive voltage Vdd and the negative voltage Vss is the resistance value of the resistor 33 and the resistance value of the phototransistor. By dividing the voltage, the integrated voltage V3a described above is generated at the collector terminal of the phototransistor.

  As shown in FIG. 1, the voltage generation unit 34 receives and amplifies the integrated voltage V <b> 3 a to generate a reference voltage V <b> 4 (an example of a reference physical quantity) and applies it to the guard electrode 21. In this case, the voltage generator 34 forms a feedback loop together with the guard electrode 21, the detection electrode 22, the current / voltage converter CV (the current / voltage converter 23 and the integrator 24), the drive circuit 25 and the photocoupler 26 of the floating circuit 11. The reference voltage V4 is generated by performing an amplification operation that amplifies the integrated voltage V3a so as to reduce the potential difference Vdi.

  In this example, as an example, the voltage generation unit 34 includes an AC amplifier circuit 34a, a phase compensation circuit 34b, and a booster circuit 34c as shown in FIG. Here, the AC amplifier circuit 34a generates the first voltage Va by inputting and amplifying the integrated voltage V3a. In this case, the AC amplifier circuit 34a generates the first voltage Va, whose absolute value of the voltage value changes, by an amplification operation in response to the increase / decrease of the absolute value of the voltage value of the integrated voltage V3a. The phase compensation circuit 34b receives the first voltage Va, adjusts its phase, and outputs it as the second voltage Vb in order to stabilize the feedback control operation (prevent oscillation). As an example, the step-up circuit 34c is configured using a step-up transformer, and boosts the second voltage Vb at a predetermined magnification (by increasing the absolute value without changing the polarity) as an output of the feedback loop. The reference voltage V4 is generated and applied to the guard electrode 21.

  The AC amplifier circuit 34a amplifies the integrated voltage V3a with a preset initial gain G0 immediately after the start of operation, and receives a switching signal S1 (described later) from the gain switching signal generator 35 (switching signal S1). Is high level), the gain is multiplied by α (a positive number exceeding 1) to be changed to gain (α × G0), and the integrated voltage V3a is amplified with the changed gain (α × G0). . The AC amplifier circuit 34a changes the gain (α × G0) to the gain G0 when the input of the switching signal S1 from the gain switching signal generator 35 is stopped (when the switching signal S1 is at a low level). Then, the integrated voltage V3a is amplified with this gain G0. Thus, the gain of the feedback loop of the voltage measuring apparatus 1 is also output from the gain switching signal generator 35 when the gain when the switching signal S1 is not output from the gain switching signal generator 35 is G. Α × G in synchronism with the timing at which the level of the switching signal S1 is switched to high level, low level, high level, low level,... (That is, in synchronization with the half cycle of the switching signal S1). , G, α × G, G,...

  The gain switching signal generation unit 35 generates the switching signal S1 at a predetermined constant period and outputs the switching signal S1 to the voltage generation unit 34, the processing unit 36, and the correction deviation unit 3. In this example, as an example, the gain switching signal generation unit 35 outputs a pulse signal (rectangular wave signal) with a duty ratio of 0.5 as the switching signal S1. In this example, when the switching signal S1 is at a high level, the output state of the switching signal S1 is indicated, and when the switching signal S1 is at a low level, the stop state of the switching signal S1 is indicated.

  As an example, the processing unit 36 includes two A / D converters, a CPU, and a memory (all not shown). The processing unit 36 operates based on the reference voltage V4 output from the voltage generation unit 34 and the switching signal S1 output from the gain switching signal generation unit 35 by the CPU operating according to the program stored in the memory. Then, the AC voltage V1 (physical quantity) of the measuring object 4 is measured based on the gain evaluation process for evaluating the gain of the feedback loop of the voltage measuring unit 2 and the later-described equivalent AC voltage V17 output from the deviation correcting unit 3. Voltage measurement processing to be performed, and waveform display processing to display the waveform of the measured AC voltage V1 on the display unit 37. In the memory, the magnification α and the reference value Dr used in the pass / fail determination process are stored in advance.

  The display unit 37 is configured by a display device such as an LCD (Liquid Crystal Display) as an example. In addition, when the display unit 37 executes the display process, the display unit 37 inputs the above-described contents such as the result of the pass / fail determination process from the processing unit 36 and displays it on the screen.

  As illustrated in FIG. 1, the deviation correction unit 3 includes, as an example, a first addition unit 41, a second addition unit 42, a first attenuation unit (attenuator) 43, a second attenuation unit (attenuator) 44, and a VCA (voltage control). Type amplifier) 45, a switching unit 46, a detection unit 47, and an amplification unit 48, and constitutes a second body circuit unit. The deviation correction unit 3 changes the amplitude generated in the waveform of the reference voltage V4 as a reference physical quantity (half of the switching signal S1) when the gain of the feedback loop in the voltage measuring unit 2 is switched in synchronization with the switching signal S1. Voltage fluctuation for each cycle) and control deviation (difference between AC voltage V1 and reference voltage V4) existing in this feedback loop are corrected, and equivalent AC as an equivalent physical quantity having the same waveform as AC voltage V1 as a physical quantity A voltage V17 is generated.

  Specifically, the first addition unit 41 adds a reference voltage V4 output from the voltage generation unit 34 and a later-described primary addition voltage (primary addition physical quantity) V13 output from the switching unit 46, and The primary correction reference voltage V11 is output as the primary correction reference physical quantity. The second addition unit 42 adds the primary correction conversion voltage V11 and a later-described secondary addition voltage (secondary addition physical quantity) V16 output from the second attenuation unit 44, and outputs the result as an equivalent AC voltage V17.

  The first attenuating unit 43 receives the reference voltage V4, attenuates the amplitude with a predetermined attenuation rate, and outputs the attenuated voltage V12. The VCA 45 receives the attenuation voltage V12 and amplifies the attenuation voltage V12 with an amplification factor according to a voltage value of a control voltage V15 (described later) output from the amplifying unit 48, and a primary addition voltage V13 as a primary addition physical quantity. Is output.

  The switching unit 46 receives the primary addition voltage V13 and the switching signal S1 output from the gain switching signal generation unit 35. In addition, the switching unit 46 stops the operation of outputting the primary addition voltage V13 to the first addition unit 41 and the output of the primary addition voltage V13 every half cycle of the switching signal S1 in synchronization with the switching signal S1. To perform the operation (operation to output zero volts). In this example, the switching unit 46 stops the output of the primary addition voltage V13 when the switching signal S1 is at a high level (when the gain of the feedback loop is α × G (period)), and the switching signal S1 is When the level is low (when the gain of the feedback loop is G (period)), the primary addition voltage V13 is output.

  As an example, the detection unit 47 includes a multiplier and a low-pass filter (both not shown). In the detection unit 47, the multiplier detects the primary correction reference voltage V11 in synchronization with the switching signal S1 (synchronous detection) and outputs a detection voltage (DC voltage), and the low-pass filter averages the detection voltage. (Integrate) and output as the final detection voltage V14. The detection unit 47 outputs the detection voltage by detecting the primary correction reference voltage V11 by envelope detection instead of the configuration for outputting the detection voltage by the synchronous detection, and the low-pass filter detects the detection voltage. A configuration in which the voltages are averaged (integrated) and output as the final detection voltage V14 may be employed. The amplifying unit 48 amplifies the detected voltage V14 with a predetermined amplification factor and outputs the amplified voltage as a control voltage V15. The second attenuation unit 44 multiplies the primary addition voltage V13 by 1 / (α-1) to generate a secondary addition voltage V16 as a secondary addition physical quantity, and outputs the secondary addition voltage V16 to the second addition unit 42.

  Next, the measurement operation for the AC voltage V1 of the measurement object 4 by the voltage measurement device 1 will be described.

  First, the floating circuit unit 11 (or the entire voltage measurement device 1) is positioned in the vicinity of the measurement object 4 so that the detection electrode 22 faces the measurement object 4 in a non-contact state. Thereby, as shown in FIG. 1, the capacitance C <b> 0 is formed between the detection electrode 22 and the measurement object 4. In this case, the capacitance value of the capacitance C0 changes in inverse proportion to the distance between the detection electrode 22 and the measurement object 4, but after the floating circuit unit 11 is once disposed, the environment such as temperature is a constant condition. Below it is a constant value. Generally, the capacitance value of the electrostatic capacitance C0 is an extremely small value (for example, about several pF to several tens pF).

  Next, in the activated state of the voltage measuring device 1, the gain switching signal generation unit 35 outputs the switching signal S <b> 1 to the voltage generation unit 34, the processing unit 36, and the deviation correction unit 3.

  In the voltage measuring unit 2, each component constituting the feedback loop synchronizes the gain of the entire feedback loop with the switching signal S1 such as G, α × G, G, α × G,. The feedback control operation for causing the reference voltage V4 to follow the AC voltage V1 by raising or lowering the reference voltage V4 so that the current signal I flowing between the detection electrode 22 and the measurement object 4 is reduced. Run.

  Specifically, when the potential difference Vdi between the AC voltage V1 of the measuring object 4 and the voltage of the guard electrode 21 (reference voltage, voltage of the reference voltage V4) is increasing (for example, due to the increase of the AC voltage V1). When the potential difference Vdi is increased), the amount of current of the current signal I flowing (inflowing) into the current-voltage conversion circuit 23 of the current-voltage conversion unit CV from the measurement object 4 via the detection electrode 22 increases. To do. In this case, the current-voltage conversion circuit 23 reduces the voltage value of the output detection voltage V2. In the integrating circuit 24, due to the decrease in the detection voltage V2, the current flowing from the output terminal of the second operational amplifier 24d to the inverting input terminal via the capacitor 24c increases. For this reason, the integration circuit 24 increases the voltage of the integration voltage V3.

  As the integrated voltage V3 rises, the transistor 25b of the drive circuit 25 shifts to a deep on state. Thereby, in the photocoupler 26, the current flowing through the light emitting diode increases, and the resistance of the phototransistor decreases. Therefore, the integrated voltage V3a generated by dividing the potential difference (Vdd−Vss) between the resistance value of the resistor 33 and the resistance value of the phototransistor decreases. The voltage generation unit 34 increases the voltage value of the generated reference voltage V4 based on the integrated voltage V3a. In this voltage measurement apparatus 1, the current-voltage conversion circuit 23, the integration circuit 24, the drive circuit 25, the photocoupler 26, and the voltage generation unit 34 of the first main body circuit unit 12 that constitute the feedback loop in this way are measured objects. By detecting an increase in the AC voltage V1 of the body 4 and performing a feedback control operation for increasing the voltage value of the reference voltage V4, the voltage of the guard electrode 21 (the voltage of the reference voltage V4) is made to follow the AC voltage V1. .

  On the other hand, when the potential difference Vdi increases due to the decrease in the AC voltage V1, the amount of current of the current signal I that flows out (flows out) from the current-voltage conversion circuit 23 to the measurement object 4 via the detection electrode 22 increases. At this time, the current-voltage conversion circuit 23 of the current-voltage conversion unit CV constituting the feedback loop performs an operation opposite to the above-described feedback control operation to reduce the voltage of the reference voltage V4. The voltage of the electrode 21 (the voltage of the reference voltage V4) is made to follow the AC voltage V1.

  Thus, in the voltage measuring apparatus 1, the feedback control operation for causing the voltage of the guard electrode 21 (the voltage of the reference voltage V4) to follow the AC voltage V1 is executed in a short time, and the voltage of the guard electrode 21 (the first calculation). Due to the virtual short-circuit of the amplifier 23c, the voltage of the detection electrode 22) converges within the control deviation corresponding to each gain G, α × G of the feedback loop. Specifically, when the gain of the feedback loop is G, the reference voltage V4 converges to the reference voltage V4a that deviates from the AC voltage V1 by a control deviation corresponding to this gain, and when the gain of the feedback loop is α × G. The control voltage corresponding to the gain converges to the reference voltage V4b that deviates from the AC voltage V1. In this case, the reference voltage V4b converges to a value closer to the AC voltage V1 by the amount that the gain of the feedback loop is higher than the gain of the reference voltage V4a (that is, the control deviation becomes smaller).

  In this state, the processing unit 36 executes a gain evaluation process for evaluating the gain of the feedback loop in the voltage measuring unit 2. In this gain evaluation process, the processing unit 36 first samples the reference voltage V4 with one A / D converter, and in synchronization with the switching signal S1, the reference voltage V4a when the gain of the feedback loop is G, The voltage waveform data of the reference voltage V4b when the gain is α × G is acquired and stored in the memory (voltage acquisition process). Next, the processing unit 36 calculates a difference ΔV4 (= V4b−V4a) between the acquired two reference voltages V4a and V4b, and calculates the calculated difference ΔV4 as one of the two reference voltages V4a and V4b. A change rate H (= ΔV4 / V4) of the reference voltage V4 is calculated by dividing by the reference voltage V4 (change rate calculation process).

  Subsequently, the processing unit 36 compares the calculated change rate H with the reference value Dr stored in the memory, and when the change rate H is equal to or greater than (or exceeds) the reference value Dr, the gain α × G is good. If the change rate H is less than (or less than) the reference value Dr, the gain α × G is good (the gain α × G is sufficient). (A pass / fail judgment process). Further, the processing unit 36 stores the determination result in the internal memory and causes the display unit 37 to display the determination result. Thereby, the gain evaluation process is completed.

  On the other hand, in parallel with the execution of the gain evaluation process by the processing unit 36, in the deviation correction unit 3, the first attenuation unit 43 receives the reference voltage V4 output from the voltage generation unit 34 (reference voltages V4a and V4b). Are alternately input), attenuated at a predetermined attenuation rate, and output to the VCA 45 as the attenuation voltage V12. The VCA 45 amplifies the attenuated voltage V12 according to the control voltage V15 output from the amplifying unit 48, and outputs the amplified voltage V12 to the switching unit 46 and the second attenuating unit 44 as the primary added voltage V13.

  The switching unit 46 outputs the primary addition voltage V13 to the first addition unit 41 when the switching signal S1 is at a low level (when the gain of the feedback loop is G) in synchronization with the switching signal S1. When the signal S1 is at a high level (when the gain of the feedback loop is α × G), the output of the primary addition voltage V13 to the first addition unit 41 is stopped (zero volt is output to the addition unit 31). Execute. The second attenuation unit 44 always executes an operation of multiplying the primary addition voltage V13 by 1 / (α-1) and outputting it as the secondary addition voltage V16 to the second addition unit 42.

  In this state, the first adder 41 inputs the reference voltage V4 (inputs the reference voltages V4a and V4b alternately) and outputs each voltage (primary addition) output from the switching unit 46 in synchronization with the switching signal S1. The voltage V13 or zero volts) is alternately added to the reference voltage V4 and output as the primary correction reference voltage V11 (primary correction processing). Specifically, when the switching signal S1 is at a high level, the first addition unit 41 adds zero volts output from the switching unit 46 to the reference voltage V4b output from the voltage generation unit 34 (that is, The reference voltage V4b is output as it is) as the primary correction reference voltage V11. In addition, when the switching signal S1 is at a low level, the first addition unit 41 adds the primary addition voltage V13 output from the switching unit 46 to the reference voltage V4a output from the voltage generation unit 34, It outputs as the next correction reference voltage V11.

  The detection unit 47 detects the primary correction reference voltage V11 output from the first addition unit 41 in this way in synchronization with the switching signal S1, and outputs a detection voltage V14. Further, the amplifying unit 48 amplifies the detection voltage V14 and outputs it to the VCA 45 as the control voltage V15. In this case, the timing of synchronous detection in the detection unit 47 and the switching timing of the reference voltages V4a and V4b output from the voltage generation unit 34 are both synchronized with the switching signal S1. For this reason, the detection voltage V14 output from the detection unit 47 is the difference between the primary correction reference voltage V11 at the time of low gain G and the primary correction reference voltage V11 at the time of high gain (α × G), that is, the reference voltage. The difference Vdif (= V4b) between the voltage obtained by adding the primary addition voltage V13 to V4a (reference voltage V4 at low gain G) and the reference voltage V4b (reference voltage V4 at high gain (α × G)) − (V4a + V13)), which is a voltage value (for example, a proportional voltage value). Similarly, the control voltage V15 generated by amplifying the detection voltage V14 has a voltage value (for example, a proportional voltage value) corresponding to the difference Vdif.

  As a result, when the difference Vdif is large, the detection voltage V14, and hence the control voltage V15, also increases, and the primary addition voltage V13 output from the VCA 45 also increases. On the other hand, when the difference Vdif is small, the detection voltage V14, and hence the control voltage V15, is also small, and the primary addition voltage V13 output from the VCA 45 is also small.

  In this way, the detection unit 47, the amplification unit 48, the VCA 45, and the switching unit 46 constitute a feedback circuit (negative feedback path) for the first addition unit 41, and the first addition unit 41 when the switching signal S1 is at a low level. Feedback control of the value of the primary addition voltage V13 (primary addition voltage V13 output from the VCA 45) added to the reference voltage V4a (execution of the primary addition physical quantity generation process) causes the switching signal S1 to be at a low level. Sometimes the value (V4a + V13) of the primary correction reference voltage V11 output from the first addition unit 41 and the value (V4b) of the primary correction reference voltage V11 output from the first addition unit 41 when the switching signal S1 is at a high level. The difference between and is close to zero. In other words, by this feedback control, the value (V4a + V13) of the primary correction reference voltage V11 output from the first addition unit 41 when the switching signal S1 is at a low level is output from the first addition unit 41 when the switching signal S1 is at a high level. It is converged (substantially matched) to the value (V4b) of the output primary correction reference voltage V11. That is, the primary addition voltage V13 output from the VCA 45 is controlled to a state that substantially matches the difference ΔV4 (= V4b−V4a).

  In this state, the second attenuation unit 44 multiplies the primary addition voltage V13 (a voltage substantially equal to the difference ΔV4) by 1 / (α-1) and outputs it to the second addition unit 42 as the secondary addition voltage V16. To do. The second addition unit 42 adds the secondary correction voltage V16 (primary addition) output from the second attenuation unit 44 to the primary correction reference voltage V11 (= reference voltage V4b) output from the first addition unit 41. The voltage V13 (= ΔV4) multiplied by 1 / (α-1)) is added and output to the processing unit 36 as an equivalent AC voltage V17 (physical quantity generation process).

  On the other hand, as in the voltage measuring unit 2 of the voltage measuring device 1, the following relationship is established in the measuring device configured to periodically switch the gain of the feedback loop between G and α × G.

As described above, the voltage measuring unit 2 is configured as a feedback control type measuring apparatus that receives the AC voltage V1 and outputs the reference voltage V4. Since the voltage measuring unit 2 having this configuration takes the AC voltage V1 as an input (target value) and the reference voltage V4 as an output (control amount) is also the difference U (output error (control deviation) with respect to the input), Then, it can be regarded as a model that performs feedback control so that “error U”) approaches zero (zero volt). Therefore, when the amplification factor of the feedback loop of the voltage measuring unit 2 is G, the following equations (1) and (2) are established.
U = V1-V4a (1)
V4a = G × U (2)

Further, when the ratio of the error U to the input V1 is considered as the error rate e1, the error rate e1 is expressed by the following equation (3).
Error rate e1 = U / V1 = 1 / (1 + G) (3)

On the other hand, when the amplification factor of the entire feedback loop is changed to α × G, the following equations (4) and (5) hold.
U = V1-V4b (4)
V4b = α × G × U (5)

Further, when the ratio of the error U to the input V1 is considered as the error rate e2, the error rate e2 is expressed by the following equation (6).
Error rate e2 = U / V1 = 1 / (1 + α × G) (6)

Next, when the difference between the error rates e1 and e2 is ε, ε is expressed by the following equation (7).
ε = e1-e2
= 1 / (1 + G) -1 / (1 + α × G)
= (Α-1) × G / (1+ (α + 1) × G + α × G ² ) (7)

Note that ε is also expressed by the following formula (8).
ε = e1-e2
= (V1-V4a) / V1- (V1-V4b) / V1
= (-V4a + V4b) / V1
= ΔV4 / V1 (8)

Further, the gain G is usually set to a value of about several hundreds to several hundreds and is sufficiently larger than the numerical value 1 (G >> 1). Further, since the magnification α may be about 2 to 3, G is a sufficiently large value in relation to the magnification α. Therefore, the above equation (7) can be approximated as the following equation (9).
ε≈ (α−1) × (1 / (1 + α × G)) (9)

In addition, since (1 / (1 + α × G)) in the right equation of Equation (9) is the error rate e2 from Equation (6), ε is further expressed as Equation (10) below. .
ε≈ (α-1) × e2 (10)

Moreover, since ε is also expressed by the equation (8), when taking the above equation (6) into consideration,
U = V1 × e2 = ΔV4 / (α-1) (11)

Further, from the above equations (4) and (10), the AC voltage V1 is expressed as the following equation (12).
V1 = V4b + U = V4b + ΔV4 / (α-1) (12)

  In this case, V4b on the right side of Expression (12) is a control amount at the time of high gain (gain (α × G)) that is a control amount closer to V1 as the target value. ΔV4 / (α-1) on the right side, which is the difference, indicates the control deviation of the feedback loop.

  In the deviation correction unit 3, as described above, the first addition unit 41 is in a period during which the reference voltage V4a (= V4b−ΔV4) is output from the voltage generation unit 34 (when the switching signal S1 is at a low level). The primary added voltage V13 (= ΔV4) is added to the reference voltage V4a, and during the period when the reference voltage V4b is output from the voltage generator 34 (when the switching signal S1 is at a high level), the reference voltage V4b Are added to each other (the reference voltage V4b is output as it is) and output as the primary correction reference voltage V11. That is, the first adder 41 aligns the input reference voltage V4 with the reference voltage V4b at the time of high gain and outputs it as the primary correction reference voltage V11.

  In addition, the second addition unit 42 performs a primary addition voltage V13 (= ΔV4) obtained by multiplying the primary correction reference voltage V11 (= reference voltage V4b) by 1 / (α−1) in the second attenuation unit 44. ) Is added to output an equivalent AC voltage V17. For this reason, this equivalent alternating voltage V17 is represented by V4b + ΔV4 / (α−1). This is the same as the expression on the right side of the expression (12).

  Therefore, while inputting the reference voltages V4a and V4b that are alternately output from the voltage generator 34, based on these reference voltages V4a and V4b, the equivalent AC voltage V17 equivalent to the AC voltage V1 (the waveform is equivalent), that is, Then, an equivalent AC voltage V17 in which voltage fluctuations synchronized with the switching signal S1 (voltage fluctuations for each half cycle of the switching signal S1) and control deviations are eliminated is generated and output.

  In this example, since the switching signal S1 is an asynchronous signal with the AC voltage V1 of the measurement object 4, the cycle thereof is less than or equal to the cycle of the AC voltage V1 as shown in FIG. In some cases, the period of the AC voltage V1 may be exceeded. However, in any case, when the deviation correction unit 3 operates as described above, as shown in FIGS. 4 and 5, voltage fluctuations synchronized with the switching signal S1 (every half cycle of the switching signal S1). A smooth waveform equivalent AC voltage V17 (a waveform indicated by a thin solid line) in which the voltage variation and the control deviation are eliminated is generated. Each parameter such as gain G, α × G (denoted as “αG” in the drawings) in FIGS. 4 and 5 has already been described, and thus individual description thereof will be omitted.

  The processing unit 36 receives the equivalent AC voltage V17 output from the second addition unit 42 of the deviation correction unit 3, and A / D-converts the equivalent AC voltage V17 with another A / D converter. The voltage waveform data is acquired and stored in the memory. Further, the processing unit 36 performs a voltage measurement process and a waveform display process based on the voltage waveform data stored in the memory.

  First, in the voltage measurement process, the processing unit 36 calculates (measures) an electrical characteristic value such as an effective voltage value, an amplitude, and a period (or frequency) of the equivalent AC voltage V17 based on the voltage waveform data of the equivalent AC voltage V17. And stored in the memory and displayed on the display unit 37. Next, in the waveform display process, the processing unit 36 causes the display unit 37 to display the waveform (voltage waveform) of the equivalent AC voltage V17 based on the voltage waveform data. In this case, the equivalent AC voltage V17 measured by the processing unit 36 is a voltage output from the deviation correction unit 3 as a voltage equivalent to the AC voltage V1 as described above. For this reason, the voltage measurement process and the waveform display process for the AC voltage V1 are completed by completing the voltage measurement process and the waveform display process for the equivalent AC voltage V17.

  As described above, according to the voltage measuring apparatus 1 and the measurement method executed by the voltage measuring apparatus 1, the gain is set to G for evaluation of the feedback control gain (feedback loop gain) in the voltage measuring unit 2. And α × G, the primary correction reference voltage V11 (= reference voltage) is obtained by adding the primary addition voltage V13 (= ΔV4) to the reference voltage V4a during the period when the gain is G. V4b), and during the period when the gain is α × G, the primary correction processing for outputting the reference voltage V4b as the primary correction reference voltage V11 as it is, and the primary addition voltage V13 are multiplied by 1 / (α-1). Generating a secondary addition voltage V16 and adding the secondary addition voltage V16 to the primary correction reference voltage V11 to generate an equivalent AC voltage V17 equivalent to the AC voltage V1; The detection voltage V14 obtained by synchronously detecting the primary correction reference voltage V11 in synchronization with the switching timing of G, α × G (switching cycle; half cycle of the switching signal S1) approaches zero volts (in other words, gain A voltage corresponding to the difference between the primary correction reference voltage V11 when G is G and the primary correction reference voltage V11 when the gain is α × G and the detected voltage approaches zero volts), the reference voltage By executing a primary addition physical quantity generation process that attenuates V4 to generate a primary addition voltage V13, a gain evaluation process for the gain of feedback control is executed to ensure the reliability of the measurement of the AC voltage V1. On the other hand, the waveform of the AC voltage V1 is displayed on the display unit 37 as a smooth waveform (a waveform in which voltage fluctuation due to switching of the gain of feedback control does not occur) and measured. Can.

  Next, a current measuring device will be described as an example.

  As shown in FIG. 6, the current measurement device 51 includes a current measurement unit 52 and a deviation correction unit 3, and is configured to be able to measure a current I1 as a physical quantity that flows through an electric wire 54 as a measurement object. In addition, about the structure same as the voltage measuring apparatus 1 mentioned above, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

  The current measurement unit 52 includes a magnetic core 61, a magnetoelectric conversion element 62, a current generation unit 63, a negative feedback coil 64, a current-voltage conversion unit 65, a gain switching signal generation unit 35, a processing unit 66, and a display unit 37. The current I1 can be measured by the flux method. As an example, the magnetic core 61 is configured such that an electric wire 54 can be inserted in a live state using a split-type core that can be opened and closed.

  The magnetoelectric conversion element 62 (elements hatched in FIG. 6) is composed of a Hall element or a flux gate. In this example, as an example, the magnetoelectric conversion element 62 is configured by using a Hall element, and the combined magnetic flux φ0 (the magnetic flux φ1 generated in the magnetic core 61 due to the current I1 flowing through the electric wire 54 and the negative feedback coil) 64), a detection voltage V51 proportional to the combined magnetic flux φ0 is generated, and the current generating unit 63 generates a detected voltage V51 proportional to the combined magnetic flux φ0. Output.

  For example, the current generation unit 63 is configured by a current source capable of controlling the output current, and generates a reference current I2 having a current value proportional to the voltage value of the detection voltage V51 output from the magnetoelectric conversion element 62 as a reference physical quantity (current The generated reference current I2 is supplied to the negative feedback coil 64 from one end 64a. In addition, the current generation unit 63 synchronizes with the timing of the switching signal S1 output from the gain switching signal generation unit 35, and sets the gain when generating the reference current I2 from the detection voltage V51 for each half cycle of the switching signal S1. By switching, the gain of the feedback loop composed of the magnetoelectric conversion element 62, the current generator 63, and the negative feedback coil 64 is switched alternately between the gain G and the gain (α × G).

  Specifically, for example, when the switching signal S1 is at a low level, the current generator 63 outputs the reference current I2a by switching the gain of the feedback loop to the gain G, and when the switching signal S1 is at a high level, the current generator 63 performs feedback. The gain of the loop is switched to the gain (α × G) and the reference current I2b is output. When not particularly distinguished, the reference currents I2a and I2b are collectively referred to as a reference current I2.

  The negative feedback coil 64 is wound around the magnetic core 61, and the number of turns (number of turns) is defined to be n times (n is a number of 1 or more). The negative feedback coil 64 has a function of canceling the magnetic flux φ1 generated in the magnetic core 61 due to the current I1 by generating the magnetic flux φ2 in the magnetic core 61 when the reference current I2 flows. ing.

  In this example, the current-voltage conversion unit 65 includes a resistor 65a and an amplifier 65b as an example. The resistor 65a is connected between the other end 64b of the negative feedback coil 64 and a reference potential (ground potential), and converts the reference current I2 supplied to the negative feedback coil 64 into a voltage V52. The amplifier 65b amplifies the voltage V52 with a constant gain and outputs it as a converted voltage (an example of a converted physical quantity) Vi. In this example, as an example, the gain when the current-voltage conversion unit 65 converts the reference current I2 into the conversion voltage Vi is defined as β (= Vi / I2).

  With this configuration, the current-voltage converting unit 65 converts the reference currents I2a and I2b as reference physical quantities by the gain β to convert them into converted voltages Via and Vib as converted physical quantities, and the processing unit 66 and the deviation correcting unit 3 Output to. That is, the conversion voltage Via is output as I2a × β, and the conversion voltage Vib is output as I2b × β. The current-voltage converter 65 converts the reference current I2 into a voltage using a resistor 65a. Although not shown, a known current-voltage converter using an operational amplifier (op amp) is employed. The conversion voltage Vi can also be converted.

  As an example, the processing unit 66 includes two A / D converters, a CPU, and a memory (all not shown). In addition, the processing unit 66 operates according to a program stored in the memory so that the conversion voltage Vi output from the current-voltage conversion unit 65 and the switching signal S1 output from the gain switching signal generation unit 35 are obtained. Based on the gain evaluation process for evaluating the gain of the feedback loop of the current measuring unit 52 and the later-described equivalent conversion voltage V27 (equivalent conversion physical quantity) output from the deviation correction unit 3, the current I1 ( Current measurement processing for measuring (physical quantity) and waveform display processing for displaying the waveform of the measured current I1 on the display unit 37. In the memory, the magnification α and the reference value Dr used in the pass / fail determination process are stored in advance.

  The deviation correction unit 3 has the same configuration as the deviation correction unit 3 in the voltage measuring apparatus 1 described above, that is, as shown in FIG. 6, the first addition unit 41, the second addition unit 42, the first attenuation unit 43, the second attenuation unit. The configuration includes an attenuating unit 44, a VCA 45, a switching unit 46, a detecting unit 47, and an amplifying unit 48. Conversion voltages Via and Vib are input instead of the reference voltages V4a and V4b, and equivalent conversion is performed instead of the equivalent AC voltage V17. The difference is that the voltage V27 is generated and output.

  Therefore, a detailed operation for each component of the deviation correction unit 3 in this example is omitted, and an outline operation will be described. The deviation correction unit 3 operates in the same manner as the deviation correction unit 3 of the voltage measurement device 1 based on the conversion voltages Via and Vib, so that the gain of the feedback loop in the current measurement unit 52 changes the switching loop signal. A change in amplitude (a voltage change for each half cycle of the switching signal S1, ie, a difference between the conversion voltages Via and Vib) generated in the waveform of the conversion voltage Vi by switching in synchronization with S1, and a control existing in this feedback loop The deviation (difference between the physical quantity (voltage) obtained by multiplying the current I1 by the gain β and the conversion voltage Vi) corresponding to the deviation (difference between the current I1 and the reference current I2) is corrected. Thus, an equivalent conversion voltage V27 as an equivalent conversion physical quantity having the same waveform as the conversion voltage Vi (conversion physical quantity) obtained by multiplying the current I1 by the gain β is generated.

  Next, the measurement operation for the current I1 flowing through the electric wire 54 by the current detection device 1 will be described. In order to facilitate understanding of the invention, the number of turns of the negative feedback coil 64 is one (n = 1), and the current I1 flowing through the electric wire 54 and the reference current I2 flowing through the negative feedback coil 64 are equal. Suppose that the strengths of the magnetic fluxes φ1 and φ2 are equal, and the resultant magnetic flux φ0 becomes zero.

  In the current measuring unit 52, the magnetic flux φ <b> 1 is generated in the magnetic core 61 due to the current I <b> 1 flowing through the electric wire 54 when the live electric wire 54 is inserted into the magnetic core 61. doing. Further, in the magnetic core 61, the magnetic flux φ2 is generated in the direction opposite to the magnetic flux φ1 due to the reference current I2 output from the current generator 63 flowing in the negative feedback coil 64. The magnetoelectric conversion element 62 detects the combined magnetic flux φ0 of the magnetic fluxes φ1 and φ2, and outputs a detection voltage V51 proportional to the combined magnetic flux φ0 to the current generating unit 63. The current generating unit 63 determines that the detected voltage V51 is The current value of the reference current I2 is controlled so as to approach zero volts (that is, so that the combined magnetic flux φ0 approaches zero).

  That is, as shown in FIG. 7, the current measuring unit 52 configures a feedback control type measuring apparatus that uses the magnetic flux φ1 as an input (target value) and outputs the reference current I2 (control amount), so that a short time is required. Among them, the combined magnetic flux φ0 is converged within the control deviation of the feedback loop. As a result, the difference between the current I1 and the reference current I2 is also converged within the control deviation for the current.

  As described above, in the current measurement unit 52, the gain of the entire feedback loop is synchronized with the switching signal S1, and half of the switching signal S1 such as G, α × G, G, α × G,. Although it is switched every period, both the gain G and α × G are preliminarily defined as values that can converge the reference current I2 within a certain range (control deviation). The current I2a and the reference current I2b when the gain is α × G are converged to a value close to the current I1, although the values are different.

  In this state, the processing unit 66 executes a gain evaluation process for evaluating the gain of the feedback loop in the current measuring unit 52. In this gain evaluation process, the processing unit 66 first samples the conversion voltage Vi with one A / D converter, and in synchronization with the switching signal S1, the conversion voltage Via when the gain of the feedback loop is G, The voltage waveform data of the conversion voltage Vib when the gain is α × G is acquired and stored in the memory. Next, the processing unit 66 divides the acquired two voltage waveform data by the gain β of the current-voltage conversion unit 65, respectively, so that the reference current I2a when the feedback loop gain is G and the gain is α × G. The reference current I2b is acquired (calculated) and stored in the memory (current acquisition process).

  Next, the processing unit 66 calculates the difference ΔI2 (= I2b−I2a) between the two acquired reference currents I2a and I2b, and calculates the calculated difference ΔI2 as one of the two reference currents I2a and I2b. A change rate H (= ΔI2 / I2) of the reference current I2 is calculated by dividing by the reference current I2 (change rate calculation process).

  Subsequently, the processing unit 66 compares the calculated change rate H with the reference value Dr stored in the memory. When the change rate H is equal to or greater than (or exceeds) the reference value Dr, the gain α × G is good. If the change rate H is less than (or less than) the reference value Dr, the gain α × G is good (the gain α × G is sufficient). (A pass / fail judgment process). Further, the processing unit 66 stores the determination result in the internal memory and causes the display unit 37 to display it. Thereby, the gain evaluation process is completed.

  In this gain evaluation process, the conversion voltage Vi can be used instead of the reference current I2. In this case, in the current acquisition process described above, the processing unit 66 uses the conversion voltage Via when the gain of the entire feedback loop is G and the conversion voltage Vib when the gain is α × G as the reference current I2 at each gain. Is obtained and stored in the memory. In the change rate calculation process described above, the processing unit 66 calculates the difference ΔVi (= Vib−Via) between the conversion voltages Via and Vib, and calculates the calculated difference ΔVi of the two conversion voltages Via and Vib. A change rate H (= ΔVi / Vi) of the conversion voltage Vi is calculated by dividing by one of the conversion voltages Vi. In this case, as described above, Via = β × I2a and Vib = β × I2b, the change rate H of the conversion voltage Vi is the same as the change rate H of the reference current I2. For this reason, in the above-described quality determination process, the processing unit 66 determines the quality of the gain α × G using the rate of change H of the conversion voltage Vi in the same manner as the rate of change H of the reference current I2.

  On the other hand, in parallel with the execution of the gain evaluation process by the processing unit 66, the deviation correction unit 3 is based on the two conversion voltages Via and Vib, and each component such as the first addition unit 41 is the voltage measuring device described above. The equivalent conversion voltage V27 as an equivalent conversion physical quantity having the same waveform as the conversion voltage Vi (conversion physical quantity) obtained by multiplying the current I1 by the gain β by performing the same operation as each component of the deviation correction unit 3 in FIG. Is generated.

  Specifically, the first attenuating unit 43 inputs the converted voltage Vi output from the current measuring unit 52 (alternately inputs the converted voltages Via and Vib), and attenuates at a predetermined attenuation rate, It outputs to VCA45 as attenuation voltage V12. The first adder 41 inputs the conversion voltage Vi (converted voltages Via and Vib are alternately input) and outputs each voltage (primary addition voltage V13) output from the switching unit 46 in synchronization with the switching signal S1. Or zero volt) is alternately added to the conversion voltage Vi and output as the primary correction conversion voltage V11A.

  In this state, the VCA 45, the switching unit 46, the detection unit 47, and the amplification unit 48 as other components of the deviation correction unit 3 execute the same operations as the respective components of the deviation correction unit 3 in the voltage measuring device 1. The primary addition voltage V13 output from the VCA 45 is converged to a state that substantially matches the difference ΔVi (= Vib−Via) (the primary addition physical quantity generation process is executed).

  Thereby, the first addition unit 41 adds the primary addition voltage V13 (= ΔVi) to the conversion voltage Vib (conversion physical quantity) when the switching signal S1 is at a low level (when the gain of the feedback loop is G). On the other hand, when the switching signal S1 is at a high level (when the gain of the feedback loop is α × G), zero volts is added to the converted voltage Vib (converted physical quantity) (that is, the converted voltage Vib remains as it is). Are respectively output as the primary correction conversion voltage V11A (primary correction processing). The second attenuating unit 44 multiplies the primary addition voltage V13 (= ΔVi) by 1 / (α−1) and outputs it as the secondary addition voltage V16. In addition, the second addition unit 42 converts the secondary addition voltage V16 (== converted voltage Vib) output from the first addition unit 41 to the secondary correction conversion voltage V11A (= conversion voltage Vib) output from the second attenuation unit 44. ΔVi / (α-1)) is added to generate an equivalent conversion voltage V27 (= Vib + ΔVi / (α-1)) and output to the processing unit 66 (conversion physical quantity generation processing).

  The processing unit 66 inputs the equivalent conversion voltage V27 output from the second addition unit 42 of the deviation correction unit 3, and A / D converts this equivalent conversion voltage V27 with another A / D converter, The voltage waveform data is acquired, and the acquired voltage waveform data is subjected to a conversion opposite to the conversion from the reference current I2 to the conversion voltage Vi, that is, a conversion divided by the gain β in the current-voltage conversion unit 65. Thus, it is converted into current waveform data of an equivalent current I3 equivalent to the current I1 which is a physical quantity in the current measuring device 51 (physical quantity generation process). The processing unit 66 stores this current waveform data in a memory. In this case, the equivalent current I3 is expressed as V27 / β = [Vib + ΔVi / (α-1)] / β).

  As in the current measuring unit 52 of the current measuring device 51, a measuring device configured to periodically switch the gain of the feedback loop between G and α × G has the following relationship.

  As described above, the voltage measuring unit 2 is configured as a feedback control type measuring apparatus in which the magnetic flux φ1 is an input (target value) and the reference current I2 is an output (control amount), and the reference current I2 is used as a current. The voltage converter 65 converts the voltage into a converted voltage Vi with a gain β and outputs the converted voltage Vi. In this case, the magnetic flux φ1 is proportional to the current I1 flowing through the electric wire 54. The magnetic flux φ2 is proportional to the current obtained by multiplying the reference current I2 flowing through the negative feedback coil 64 by the number n of turns of the negative feedback coil 64. In this example, n is 1 as an example (that is, because the gain in the negative feedback coil 64 is 1), so the magnetic flux φ2 is proportional to the reference current I2 itself.

Thereby, each component which comprises the feedback loop to the front | former stage of the current voltage conversion part 65 in the current measurement part 52 makes the electric current I1 the input, and makes the reference electric current I2 the output, and both as a difference (control deviation) It can be regarded as a model that performs feedback control so that the error U (= I1-I2) approaches zero (zero amperes). For this reason, when the amplification factor of the feedback loop of the current measuring unit 52 is G, the following equations (51) and (52) hold.
U = I1-I2a (51)
I2a = G × U (52)

At this time, when the ratio of the error U to the input I1 is considered as the error rate e1, the error rate e1 is expressed by the following equation (53).
Error rate e1 = U / I1 = 1 / (1 + G) (53)

On the other hand, when the amplification factor of the entire feedback loop is changed to α × G, the following equations (54) and (55) hold.
U = I1-I2b (54)
I2b = α × G × U (55)

At this time, when the ratio of the error U to the input V1 is considered as the error rate e2, the error rate e2 is expressed by the following equation (56).
Error rate e2 = U / I1 = 1 / (1 + α × G) (56)

Next, when the difference between the error rates e1 and e2 is ε, ε is expressed by the following equation (57).
ε = e1-e2
= 1 / (1 + G) -1 / (1 + α × G)
= (Α-1) × G / (1+ (α + 1) × G + α × G ² ) (57)

Note that ε is also expressed by the following formula (58).
ε = e1-e2
= (I1-I2a) / I1- (I1-I2b) / I1
= (-I2a + I2b) / I1
= ΔI2 / I1 (58)

Further, since the gain G is sufficiently larger than the numerical value 1 (G >> 1) and the magnification α may be about 2 to 3, G is a sufficiently large value in relation to the magnification α. Therefore, the above equation (57) can be approximated as the following equation (59).
ε≈ (α−1) × (1 / (1 + α × G)) (59)

Further, (1 / (1 + α × G)) in the right equation of the equation (59) is an error rate e2 from the equation (56), and is further expressed as the following equation (60).
ε≈ (α−1) × e2 (60)

Since ε is expressed as the equation (58), when the above equation (56) is considered,
U = I1 × e2 = ΔI2 / (α-1) (61)

From the above equations (54) and (60), the current I1 is expressed as the following equation (62).
I1 = I2b + U = I2b + ΔI2 / (α-1) (62)

  In this case, since I2b on the right side of Expression (62) is a control amount at a high gain (gain (α × G)) that is a control amount closer to I1 as the target value, the target value and the control amount ΔI2 / (α-1) on the right side, which is the difference, indicates the control deviation of the feedback loop.

On the other hand, the conversion voltages Via and Vib output from the current measurement unit 52 are obtained by multiplying the reference currents I2a and I2b by β by the current-voltage conversion unit 65, respectively. Therefore, by applying this relationship to the above equation (62), the current I1 is expressed as the following equation (63) using the conversion voltages Via and Vib.
I1 = Vib / β + (Vib / β-Via / β) / (α-1)
= [Vib + ΔVi / (α-1)] / β (63)
Here, ΔVi = Vib−Via.

  Therefore, the processing unit 66 performs the conversion of dividing the equivalent conversion voltage V27 from the deviation correction unit 3 by β as described above to obtain the equivalent current I3 (= V27 / β = [Vib + ΔVi / (α-1)] / By calculating β), the processing unit 66 can measure (calculate) a physical quantity equivalent to the current I1.

  In this example, the switching signal S1 is a signal asynchronous with the current I1. For this reason, when the current I1 is an alternating current, the period of the switching signal S1 may be equal to or less than the period of the current I1, or may exceed the period of the current I1. However, in any case, the deviation correction unit 3 operates as described above, so that the voltage fluctuation (the switching signal S1 of the switching signal S1 is synchronized with the switching signal S1) as in the case of the voltage measuring device 1 described above. The equivalent conversion voltage V27 in which the voltage fluctuation for each half cycle) and the control deviation are eliminated is output from the deviation correction unit 3, and the voltage fluctuation synchronized with the switching signal S1 (voltage fluctuation for each half cycle of the switching signal S1) and control. The processing unit 66 calculates the equivalent current I3 from which the deviation is eliminated.

  Next, the processing unit 66 executes current measurement processing and waveform display processing based on the current waveform data of the equivalent current I3 stored in the memory.

  First, in the current measurement process, the processing unit 66 calculates (measures) electrical characteristic values such as an effective voltage value, an amplitude, and a period (or frequency) of the equivalent current I3 based on the current waveform data of the equivalent current I3. And stored in the memory and displayed on the display unit 37. Next, in the waveform display process, the processing unit 66 causes the display unit 37 to display the waveform (current waveform) of the equivalent current I3 based on the current waveform data of the equivalent current I3. In this case, since the equivalent current I3 measured by the processing unit 66 is a current equivalent to the current I1 as described above, the voltage with respect to the current I1 is completed by completing the voltage measurement process and the waveform display process for the equivalent current I3. Measurement processing and waveform display processing are completed.

  Thus, according to this current measurement device 51 and the measurement method executed by this current measurement device 51, this gain is set to G for evaluation of the feedback control gain (feedback loop gain) in the current measurement unit 52. And α × G, the primary correction voltage V11A (= conversion voltage) is obtained by adding the primary addition voltage V13 (= ΔVi) to the conversion voltage Via during the period in which the gain is G. Vib), and during the period when the gain is α × G, the primary correction processing for outputting the conversion voltage Vib as it is as the primary correction conversion voltage V11A and the primary addition voltage V13 are multiplied by 1 / (α-1). The secondary addition voltage V16 is generated and the secondary addition voltage V16 is added to the primary correction conversion voltage V11A to generate an equivalent conversion voltage V27 equivalent to the conversion voltage Vi. The detection voltage V14 obtained by synchronous detection of the primary correction conversion voltage V11A in synchronization with the amount generation processing and the gain G, α × G switching timing (half cycle of the switching signal S1) approaches zero volts (in other words, For example, a voltage corresponding to the difference between the primary correction conversion voltage V11A when the gain is G and the primary correction conversion voltage V11A when the gain is α × G is detected and the detected voltage approaches zero volts. The equivalent addition voltage V27 includes a primary addition physical quantity generation process for attenuating the conversion voltage Vi to generate the primary addition voltage V13, and a conversion opposite to the conversion from the reference current I2 to the conversion voltage Vi (conversion divided by β). And performing a physical quantity generation process for generating an equivalent current I3 equivalent to the current I1, thereby executing a gain evaluation process for the gain of the feedback control and performing measurement reliability. The waveform of the current I1 flowing through the electric wire 54 can be displayed and measured on the display unit 37 as a smooth waveform (a waveform in which no voltage fluctuation has occurred due to switching of the feedback control gain). it can.

  In the voltage measuring device 1 and the current measuring device 51 described above, the gain switching signal generation unit 35 employs a configuration that generates the switching signal S1 asynchronously with the AC voltage V1 or the current I1 (in the case of AC current). However, when the AC voltage V1 or the current I1 is an AC current (when the physical quantity of the measurement object is an AC signal), the feedback loop gain G, α × G in the voltage measurement unit 2 or the current measurement unit 52 is obtained. When the switching timing (switching cycle; half cycle of the switching signal S1) is longer than the cycle of the current I1 that is the AC voltage V1 or the AC current, as shown in FIG. A configuration in which the switching timing of G is synchronized with the zero cross point of the AC voltage V1 and the current I1 can also be employed.

  Hereinafter, a voltage measuring apparatus 1A employing this configuration will be described with reference to FIG. In addition, since the voltage measurement apparatus 1 and a basic structure are the same, the same code | symbol is attached | subjected about the same structure and the overlapping description is abbreviate | omitted.

  The voltage measuring apparatus 1A includes a gain switching signal generation unit 35A instead of the gain switching signal generation unit 35, and the processing unit 36 detects a zero-cross point of the equivalent AC voltage V17 in addition to the above-described processes. The only difference is that the zero-cross point detection processing to be performed and the control processing for the gain switching signal generation unit 35A are executed. Only this configuration will be described.

  As an example, the gain switching signal generation unit 35A is configured using a PLL (Phase Locked Loop) circuit, and is configured to be able to control the frequency and phase of the switching signal S1 having a duty ratio of 0.5. In the zero cross point detection process, the processing unit 36 detects the zero cross point (e.g., the zero cross point at the time of rising) of the equivalent AC voltage V <b> 17. In the control process for the gain switching signal generation unit 35A, the processing unit 36 detects the zero cross point of the detected equivalent AC voltage V17 and the rising or falling timing of the switching signal S1 (in this example, the zero crossing of the equivalent AC voltage V17 Since the point is the zero crossing point at the time of rising, the phase difference from the rising timing) is detected, and the control signal S2 is output to the gain switching signal generator 35A, so that the phase difference is reduced. The phase difference and frequency of the signal S1 are controlled.

  In the current measuring device 1A, the gain switching signal generation unit 35A is configured as described above, and the processing unit 36 executes the zero-cross point detection processing and the control processing for the gain switching signal generation unit 35A as described above. The rising edge of the switching signal S1 is synchronized with the zero cross point of the equivalent AC voltage V17, and the cycle of the switching signal S1 is defined as a cycle that is an integral multiple of the cycle of the equivalent AC voltage V17. Further, since the duty ratio of the switching signal S1 is 0.5 as described above, the falling edge of the switching signal S1 is also synchronized with the zero cross point of the equivalent AC voltage V17. Therefore, according to the current measuring device 1A, the switching timing of the gain G, α × G of the feedback loop is synchronized with the period of the equivalent AC voltage V17, and therefore, the gain G, α × G of the feedback loop is switched. Superimposition of the switching noise caused on the equivalent AC voltage V17 can be greatly reduced.

  The deviation correction unit 3 includes a plurality of first addition unit 41, second addition unit 42, first attenuation unit 43, second attenuation unit 44, VCA 45, switching unit 46, detection unit 47, and amplification unit 48. Although constituted by elements, a plurality of these elements can be constituted by one DSP (Digital Signal Processor). In addition, by performing A / D conversion on the input signal and the output signal to the deviation correction unit 3, a plurality of functions among the above-described elements constituting the deviation correction unit 3 are processed by the processing unit 36 (the current measuring device 51 performs processing). It is also possible to adopt a configuration provided in the portion 66).

  The voltage measuring device 1 among the voltage measuring devices 1 and 1A and the current measuring device 51 described above will be described as an example. In this case, as shown in FIG. 9, each function of the constituent elements surrounded by the alternate long and short dash line among the constituent elements of the voltage measuring section 2 and the deviation correcting section 3 is configured to be executed by a computer (CPU). Specifically, the voltage measurement unit 2 is configured to execute the functions of the AC amplification circuit 34a and the phase compensation circuit 34b, the gain switching signal generation unit 35, and the processing unit 36 constituting the voltage generation unit 34 by software. . Further, the deviation correction unit 3 is configured to execute the functions of all the components except for the two addition units 41 and 42 by software.

  Therefore, for the switching signal S1, for example, a count program that executes the function of the gain switching signal generator 35 counts the time of the half cycle of the switching signal S1, and indicates the switching signal S1 for each half cycle. It is generated by changing the value of the signal data DS1 to “0”, “1”, “0”, “1”,.

  The integrated voltage V3a is converted into integrated voltage data DV3a by the A / D converter 71 and processed by a first processing program that executes the functions of the AC amplifier circuit 34a and the phase compensation circuit 34b. The first processing program alternately amplifies the input integral voltage data DV3a as G times, α × G times, G times, α × G times,... Every half cycle of the switching signal S1, Further, in order to stabilize the feedback control operation (prevent oscillation) for the amplified data DVa, the phase is adjusted and output as the second voltage data DVb. The second voltage data DVb is converted to the second voltage Vb by the D / A converter 76 and output to the booster circuit 34c.

  The reference voltage V4 is converted into reference voltage data DV4 by the A / D converter 72 and processed by the second processing program that executes the functions of the processing unit 36, the first attenuation unit 43, and the VCA 45. Of the second processing program, the program that executes the function of the processing unit 36 executes the same processing as the processing that is executed by the processing unit 36, and the program that executes the functions of the first attenuation unit 43 and the VCA 45 The input reference voltage data DV4 is once attenuated at a predetermined attenuation rate, and the attenuated data DV12 is a control voltage calculated by a third program to be described later for executing the functions of the detector 47 and amplifier 48. Amplification is performed at an amplification factor indicated by data DV15, and primary addition voltage data DV13 is calculated.

  The primary correction reference voltage V11 is converted into primary correction reference voltage data DV11 by the A / D converter 74 and processed by a third processing program that executes the functions of the detection unit 47 and the amplification unit 48. The In the third program, the primary correction reference voltage data DV11 is detected in synchronization with the switching signal S1 and output as detection voltage data DV14. The amplifying unit 48 amplifies the detected voltage data DV14 with a predetermined amplification factor and outputs it as control voltage data DV15.

  The primary addition voltage data DV13 calculated as described above is processed by the fourth program that executes the function of the switching unit 46, and the switching signal S1 is at a high level (the switching signal data DS1 is “1”). The D / A converter 73 converts the voltage into the primary addition voltage V13 and outputs it to the first adder 41. When the switching signal S1 is at a low level (switching signal data DS1 is “0”), zero volts is output as the primary addition voltage V13.

  The primary added voltage data DV13 is processed by a fifth program that executes the function of the second attenuator 44, multiplied by 1 / (α-1), and converted into secondary added voltage data DV16. Further, it is converted to a secondary addition voltage V 16 by the D / A converter 75 and output to the second addition unit 42. The equivalent AC voltage V17 output from the second addition unit 42 is converted into equivalent AC voltage data DV17 by the A / D converter 76, and executes the function of the processing unit 36 in the second processing program. Processed by.

  In this way, by configuring each function of each of the above-described constituent elements surrounded by a one-dot chain line among the constituent elements of the voltage measuring unit 2 and the deviation correcting unit 3 with software (CPU), Α which determines the gain of the feedback loop can be freely set.

  Further, in each example of the measurement device described above, the first attenuation unit 43 and the VCA 45 are based on the reference voltage V4 output from the voltage measurement unit 2 or the converted voltage Vi output from the current measurement unit 52. Although the configuration for outputting the addition voltage V13 is employed, the difference ΔV4 generated in the reference voltage V4 output from the voltage measurement unit 2 when the gain of the feedback loop is switched, and the converted voltage Vi output from the current measurement unit 52 And the primary addition voltage (primary addition physical quantity) V13 used in the deviation correction unit 3 for correcting the control deviation of the feedback loop are small values compared to the reference voltage V4 and the conversion voltage Vi. It is. For this reason, the primary correction reference voltage V11 and the equivalent alternating voltage V17 are substantially equal to the reference voltage V4, and the primary correction reference voltage V11 and the equivalent conversion voltage V27 are substantially equal to the conversion voltage Vi. In the voltage measurement unit 2, the first attenuation unit 43 and the VCA 45 can adopt a configuration in which the primary correction reference voltage V <b> 11 or the equivalent AC voltage V <b> 17 is input instead of the reference voltage V <b> 4, or the current measurement unit 52. Then, the first attenuation unit 43 and the VCA 45 may adopt a configuration in which the primary correction reference voltage V11 or the equivalent conversion voltage V27 is input instead of the conversion voltage Vi.

DESCRIPTION OF SYMBOLS 1 Voltage measurement apparatus 2 Voltage measurement part 3 Deviation correction part 4 Measurement object 51 Current measurement apparatus 52 Current measurement part V1 AC voltage V4 Reference voltage V11 Primary correction reference voltage V13 Primary addition voltage V14 Detection voltage V16 Secondary addition voltage V17 Equivalent AC voltage

Claims (6)

A measurement device that generates a reference physical quantity corresponding to a physical quantity of a measurement object by feedback control so as to reduce a difference from the physical quantity, and measures the physical quantity of the measurement object based on the reference physical quantity. ,
For the evaluation of the gain of the feedback control, the gain is alternately switched between G and α × G (α is a positive number exceeding 1),
In the period in which the gain is G, a primary addition physical quantity is added to the reference physical quantity and output as a primary correction reference physical quantity, and in the period in which the gain is α × G, the reference physical quantity is directly used as the primary correction reference. Primary correction processing to output as a physical quantity;
The primary addition physical quantity is multiplied by 1 / (α-1) to generate a secondary addition physical quantity, and the secondary addition physical quantity is added to the primary correction reference physical quantity to generate an equivalent physical quantity equivalent to the physical quantity. Physical quantity generation processing to
The reference physical quantity is detected such that a difference between the primary correction reference physical quantity when the gain is G and the primary correction reference physical quantity when the gain is α × G is detected and the detected difference approaches zero. And a primary addition physical quantity generation process for generating the primary addition physical quantity by attenuating one of the primary correction reference physical quantity and the equivalent physical quantity. The reference physical quantity corresponding to the physical quantity of the measurement object is generated by feedback control so that the difference from the physical quantity is reduced, and the physical quantity of the measurement object is based on the converted physical quantity obtained by converting the reference physical quantity A measuring device for measuring
For the evaluation of the gain of the feedback control, the gain is alternately switched between G and α × G (α is a positive number exceeding 1),
In the period when the gain is G, a primary addition physical quantity is added to the conversion physical quantity and output as a primary correction conversion physical quantity, and in the period where the gain is α × G, the conversion physical quantity is directly used as the primary correction conversion. Primary correction processing to output as a physical quantity;
The primary addition physical quantity is multiplied by 1 / (α-1) to generate a secondary addition physical quantity, and the secondary addition physical quantity is added to the primary correction conversion physical quantity to obtain an equivalent conversion physical quantity equivalent to the conversion physical quantity. A conversion physical quantity generation process for generating
The conversion physical quantity is detected such that a difference between the primary correction conversion physical quantity when the gain is G and the primary correction conversion physical quantity when the gain is α × G is detected and the detected difference approaches zero. A primary addition physical quantity generating process for attenuating one of the primary correction conversion physical quantity and the equivalent conversion physical quantity to generate the primary addition physical quantity;
A measurement apparatus that executes a physical quantity generation process for generating an equivalent physical quantity equivalent to the physical quantity by executing a conversion opposite to the conversion from the reference physical quantity to the converted physical quantity on the equivalent converted physical quantity. When the physical quantity of the measurement object is an AC signal, a zero cross point detection process for detecting a zero cross point of the physical quantity is executed.
The measurement apparatus according to claim 1, wherein the gain switching is executed in synchronization with the detected zero-cross point and at a cycle that is an integral multiple of the cycle of the physical quantity. A measurement method for generating a reference physical quantity corresponding to a physical quantity of a measurement object by feedback control so as to reduce a difference from the physical quantity, and measuring the physical quantity of the measurement object based on the reference physical quantity. ,
For the evaluation of the gain of the feedback control, the gain is alternately switched between G and α × G (α is a positive number exceeding 1),
In the period in which the gain is G, a primary addition physical quantity is added to the reference physical quantity and output as a primary correction reference physical quantity, and in the period in which the gain is α × G, the reference physical quantity is directly used as the primary correction reference. Primary correction processing to output as a physical quantity;
The primary addition physical quantity is multiplied by 1 / (α-1) to generate a secondary addition physical quantity, and the secondary addition physical quantity is added to the primary correction reference physical quantity to generate an equivalent physical quantity equivalent to the physical quantity. Physical quantity generation processing to
The reference physical quantity is detected such that a difference between the primary correction reference physical quantity when the gain is G and the primary correction reference physical quantity when the gain is α × G is detected and the detected difference approaches zero. A primary addition physical quantity generation process for generating the primary addition physical quantity by attenuating one of the primary correction reference physical quantity and the equivalent physical quantity. The reference physical quantity corresponding to the physical quantity of the measurement object is generated by feedback control so that the difference from the physical quantity is reduced, and the physical quantity of the measurement object is based on the converted physical quantity obtained by converting the reference physical quantity A measuring method for measuring
For the evaluation of the gain of the feedback control, the gain is alternately switched between G and α × G (α is a positive number exceeding 1),
In the period when the gain is G, a primary addition physical quantity is added to the conversion physical quantity and output as a primary correction conversion physical quantity, and in the period where the gain is α × G, the conversion physical quantity is directly used as the primary correction conversion. Primary correction processing to output as a physical quantity;
The primary addition physical quantity is multiplied by 1 / (α-1) to generate a secondary addition physical quantity, and the secondary addition physical quantity is added to the primary correction conversion physical quantity to obtain an equivalent conversion physical quantity equivalent to the conversion physical quantity. A conversion physical quantity generation process for generating
The conversion physical quantity is detected such that a difference between the primary correction conversion physical quantity when the gain is G and the primary correction conversion physical quantity when the gain is α × G is detected and the detected difference approaches zero. A primary addition physical quantity generating process for attenuating one of the primary correction conversion physical quantity and the equivalent conversion physical quantity to generate the primary addition physical quantity;
A measurement method for executing a physical quantity generation process for generating an equivalent physical quantity equivalent to the physical quantity by executing a conversion opposite to the conversion from the reference physical quantity to the converted physical quantity on the equivalent converted physical quantity. When the physical quantity of the measurement object is an AC signal, a zero cross point detection process for detecting a zero cross point of the physical quantity is executed.
6. The measurement method according to claim 4, wherein the gain switching is performed in synchronization with the detected zero-cross point and at a cycle that is an integral multiple of the cycle of the physical quantity.

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