CN114236454A - Error calibration method and device of broadband resistor divider - Google Patents

Error calibration method and device of broadband resistor divider Download PDF

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Publication number
CN114236454A
CN114236454A CN202111474856.9A CN202111474856A CN114236454A CN 114236454 A CN114236454 A CN 114236454A CN 202111474856 A CN202111474856 A CN 202111474856A CN 114236454 A CN114236454 A CN 114236454A
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broadband
divider
sampling
resistor divider
voltage
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胡志远
王保林
王凯
何梓滨
郝婷婷
陈权
李绍飞
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Beijing Dongfang Measurement and Test Institute
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Beijing Dongfang Measurement and Test Institute
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/02—Testing or calibrating of apparatus covered by the other groups of this subclass of auxiliary devices, e.g. of instrument transformers according to prescribed transformation ratio, phase angle, or wattage rating
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/04—Voltage dividers

Abstract

The invention relates to an error calibration method and device of a broadband resistor voltage divider. The method comprises the following steps: s1, providing voltage signals of multiple levels for the broadband resistor voltage divider of multiple levels through multiple first channels and multiple second channels by using multiple multifunctional standard sources respectively; s2, when the multifunctional standard sources provide voltage signals of each level, the first channel is provided with a previous-level broadband resistive voltage divider, and the second channel is provided with a current-level broadband resistive voltage divider; s3, receiving and sampling the partial pressure signals of the first channels and the partial pressure signals of the second channels by using a plurality of digital sampling systems respectively; and S4, obtaining the net specific difference and the net angular difference according to the specific difference and the angular difference of the partial pressure signals of the plurality of first channels and the specific difference and the angular difference of the partial pressure signals of the plurality of second channels. The invention can improve the accuracy and precision of the calibration of the ratio difference and the angular difference of the broadband resistor divider.

Description

Error calibration method and device of broadband resistor divider
Technical Field
The invention relates to the technical field of metering, in particular to an error calibration method and device of a broadband resistor voltage divider.
Background
The proportional metering has very important function in the electrical metering, and mainly can solve the problem of range expansion. Since the measuring standard or measuring instrument usually has a high accuracy only in a certain range, if a large range of electrical values are accurately measured, the measurement is realized by a proportional device. The proportioner is usually made into an accessory type special proportioning device or a proportional standard device and is used as a range extender of various measuring devices. The proportional standard device is adopted, so that the measuring instruments can be unified into a standard form, the structure is simple and reliable, the measuring accuracy is higher than that of a direct instrument, the insulating property of a circuit can be particularly improved, and the safety of the measuring instrument and a user can be protected. With the development of measurement technology, the proportion device originally used as an accessory can be made to have higher accuracy than the measuring instrument, so that the proportion device can be used as a main standard device and matched with an auxiliary measuring instrument to complete the test work.
In the field of modern electrical precision measurement, the purpose of measurement by using proportion and proportion relation is very common. Many precision meters rely on voltage ratio and current ratio metering. The voltage proportional devices, the shunts, the variable resistors, the variable capacitors, the bridges and the attenuators are designed according to the proportion principle. Calibration of the inductive voltage divider, the bridge proportional arm, the strain gauge attenuator and the like all require a proportional standard to perform precise measurement.
The AC resistance voltage divider is an important electromagnetic device, is mainly used for the range expansion of AC voltage, and is a necessary device for widening the measurement range of the AC voltage. The AC proportional voltage divider is suitable for all AC voltage measuring instruments including AC voltage source, AC voltmeter, AC/DC converter, measuring amplifier, phase meter, etc. The precise alternating voltage and power measurement method, whether the sampling alternating current-direct current thermoelectric comparison method or the alternating current sampling measurement method, must attenuate the measured alternating voltage into a voltage which can be directly accepted by a digital collector or a thermoelectric converter through an alternating current voltage divider. The broadband alternating current source technology is widely applied to the research and production test process of national defense military equipment, and the broadband alternating current voltage can be traced to the alternating current-direct current conversion standard only through the alternating current voltage divider.
The calibration of the broadband resistive divider is a difficult problem in the field of electrical measurement, the difficulty lies in the calibration of high-accuracy specific difference and angular difference, a perfect calibration system of the broadband resistive divider is not established domestically, the measurement standard of a calibration device of the broadband resistive divider is not established, and the mature calibration standard of the broadband resistive divider is not established. The research on the broadband resistor voltage divider calibration method and the calibration device has fewer mechanisms and units. The direct current voltage ratio difference is firstly calibrated and then the alternating current-direct current difference is calibrated, and the angle difference cannot be calibrated.
Chinese patent ZL2016108844939 discloses a method for correcting an ac resistor voltage divider based on an equivalence principle to establish an error model. The patent provides an alternating current resistor voltage divider correction method for establishing an error model based on an equivalence principle, which comprises the steps of establishing a frequency error equivalent model of the alternating current resistor voltage divider, and completing the analysis of the error of the alternating current resistor voltage divider in the frequency range of 50 Hz-100 kHz by using the model. Chinese patent ZL201510999332X discloses a self-calibrating resistor divider. The patent proposes a self-calibration method of a resistor voltage divider, which realizes accurate calibration of the resistor voltage divider by a method of comparing a main voltage divider and a reference voltage divider segment by segment. The technology is limited by a reference induction voltage divider, the calibration frequency range is narrow, the voltage is lower, and the downward transmission of the specific difference of the resistance voltage divider under the alternating current low voltage can be only ensured.
Disclosure of Invention
In order to ensure that the measurement accuracy of the ratio difference and the angular difference of the broadband resistor voltage divider is high, the invention provides an error calibration method and device of the broadband resistor voltage divider.
In order to achieve the purpose, the technical scheme of the invention is as follows:
the invention provides an error calibration method of a broadband resistor voltage divider, which comprises the following steps:
s1, providing voltage signals of multiple levels for the broadband resistor voltage divider of multiple levels through multiple first channels and multiple second channels by using multiple multifunctional standard sources respectively;
s2, when the multifunctional standard sources provide voltage signals of each level, the first channel is provided with a previous-level broadband resistive voltage divider, and the second channel is provided with a current-level broadband resistive voltage divider;
s3, receiving and sampling the partial pressure signals of the first channels and the partial pressure signals of the second channels by using a plurality of digital sampling systems respectively;
and S4, obtaining the net specific difference and the net angular difference according to the specific difference and the angular difference of the partial pressure signals of the plurality of first channels and the specific difference and the angular difference of the partial pressure signals of the plurality of second channels.
According to an aspect of the present invention, before the step S1, a multifunctional standard source is used to provide voltage signals to a digital sampling system through a first channel and a second channel, respectively, so as to correct the zero point error of the digital sampling system.
According to an aspect of the present invention, the step S3 further includes: and in the process of respectively receiving and sampling the partial pressure signals of the plurality of first channels and the partial pressure signals of the plurality of second channels by using the plurality of digital sampling systems, compensating for the error of non-whole-period sampling of the plurality of digital sampling systems by using a non-whole-period compensation algorithm.
According to one aspect of the invention, the process of the non-full period compensation algorithm comprises:
establishing a mathematical model for the alternating current signals containing harmonic waves in the partial pressure signals, wherein the mathematical model comprises the following steps:
Figure BDA0003391008590000041
where ω is the angular frequency, T is the period of the divided signal, K is the number of harmonics, a0Is a direct current component, akAnd bkIs a harmonic component;
the digital sampling system is utilized to carry out non-whole period sampling on the alternating current signal to obtain a discrete signal, and the discrete signal is as follows:
Figure BDA0003391008590000042
wherein the sampling interval is Ts；
Processing the discrete signals by using a digital signal processing algorithm to obtain the frequency, amplitude and phase of each harmonic signal, wherein,
Figure BDA0003391008590000043
amplitude of the kth harmonic signal, arctan (a)k/bk) Is the phase of the kth harmonic signal;
obtaining the direct current component and each harmonic component of the voltage division signal according to the frequency, the amplitude and the phase, compensating by the following formula,
Figure BDA0003391008590000044
wherein A ═ a0,a1,a2,…,aK,b1,b2,…,bK)TA vector composed of a direct current component and a true value of each subharmonic component of the partial pressure signal is represented;
Figure BDA0003391008590000045
expressing vectors composed of estimated values of direct current components and each subharmonic component obtained by utilizing a Fourier transform principle under the non-whole period sampling condition;
Figure BDA0003391008590000051
calculating the non-integer-period sampling deviation by using an interpolation method, so that the non-integer-period sampling deviation meets the condition that | delta | is less than 1, and the complement of the whole-period sampling is as follows:
Figure BDA0003391008590000052
wherein, the sampling period is n + delta, the end point of the sampling period is between n and n + l, and the sampling point of the start point is y0，y1Is the first sample point, and the two sample points near the expected end point are ynAnd yn+l。
According to one aspect of the invention, the broadband resistive voltage divider comprises a resistive main voltage dividing portion, a capacitor box and a buffer amplifier which are connected in sequence.
According to one aspect of the invention, the upper-stage broadband resistor divider is a 2V broadband resistor divider, a 4V broadband resistor divider, an 8V broadband resistor divider, a 16V broadband resistor divider, a 32V broadband resistor divider, a 64V broadband resistor divider, a 120V broadband resistor divider, a 240V broadband resistor divider, and a 480V broadband resistor divider;
the broadband resistor divider at the current stage is a 4V broadband resistor divider, an 8V broadband resistor divider, a 16V broadband resistor divider, a 32V broadband resistor divider, a 64V broadband resistor divider, a 120V broadband resistor divider, a 240V broadband resistor divider, a 480V broadband resistor divider and a 1000V broadband resistor divider.
According to one aspect of the invention, the voltage signals output by the multifunctional standard source and used as the broadband resistor divider are 0.8V, 2V, 4V, 8V, 16V, 32V, 64V, 120V, 240V and 480V.
The invention also provides an error calibration device of the broadband resistive voltage divider, which is realized by the error calibration method of the broadband resistive voltage divider, and the error calibration device comprises: a multifunctional standard source, a first broadband resistive voltage divider, a second broadband resistive voltage divider, a first digital sampling system and a second digital sampling system,
the first broadband resistive voltage divider is provided with a first channel, and the second broadband resistive voltage divider is provided with a second channel;
the first broadband resistive divider is connected with the first digital sampling system through the first channel, and the second broadband resistive divider is connected with the second digital sampling system through the second channel;
the multifunctional standard source provides voltage signals for the first broadband resistive divider and the second broadband resistive divider through the first channel and the second channel, respectively.
According to another aspect of the invention, the first digital sampling system and the second digital sampling system each comprise: 3458A digital sampling module, PXIe cabinet, controller, PXI-5421 signal generation module, GPIB control module and GPIB line,
the PXIe case, the controller and the PXI-5421 signal generation module jointly control two 3458A digital sampling modules to perform synchronous sampling;
the GPIB wire is used for connecting the 3458A digital sampling module, the PXIe case, the controller, the PXI-5421 signal generating module and the GPIB control module in sequence.
According to another aspect of the invention, the first digital sampling system and the second digital sampling system each comprise: a PXI-5922 digital sampling module, a PXIe-6674T clock module, a GPIB control module, a GPIB wire, a PXIe case and a controller,
the PXIe-6674T clock module is used for enabling the sampling time interval of the two PXI-5922 digital sampling modules to be more accurate;
the GPIB wire connects the PXI-5922 digital sampling module, the PXIe case, the controller, the PXIe-6674T clock module and the GPIB control module in sequence.
Has the advantages that:
according to the scheme, aiming at the source tracing problem of the broadband (10Hz-1MHz) resistance voltage divider, the invention provides a 3458A-based low-frequency resistance voltage divider error calibration device (10Hz-1kHz) and a PXI-5922-based high-frequency resistance voltage divider error calibration device (1kHz-1MHz), expands the measurement frequency of the resistance voltage divider to 1MHz, and improves the calibration repeatability and stability of the broadband resistance voltage divider.
Aiming at the impedance network and matching problem of the broadband resistor voltage divider, the idea of taking the buffer amplifier for impedance conversion as a component of the broadband resistor voltage divider and carrying out integral error calibration on the resistor voltage dividing part, the capacitor box and the buffer amplifier of the resistor voltage divider is provided. Therefore, the calibration of the broadband resistive divider is feasible, and the measurement accuracy of the broadband resistive divider is improved.
Aiming at the problems of jitter in sampling time base and asynchrony between a sampling signal and a measurement signal, a non-integer period compensation algorithm is adopted, a PXI-5421 signal generation card is adopted as an external synchronous sampling trigger device in a 3458A low-frequency device, a PXI-5922 high-frequency device adopts a PXIe-6674T clock card as an internal sampling clock, the sampling deviation of the integer period is smaller than 0.0002 sampling interval, the repeatability is smaller than 0.0001 sampling interval, the influence of non-integer period sampling error is overcome, and the measurement repeatability of the alternating voltage proportion reaches 2 multiplied by 10-6。
In order to solve the tracing problem of the specific difference and angular difference values of the broadband resistance voltage divider and reduce the uncertainty of a calibration result, a high-low frequency resistance voltage divider error calibration device is developed by comprehensively adopting a plurality of technical means of a frequency-dividing-band calibration technology, an increase slow-release overall calibration technology, a full-range half-load recursive calibration technology, a synchronous sampling measurement technology and non-integer-period sampling compensation.
Drawings
FIG. 1 is a flow chart of a method for error calibration of a broadband resistive divider according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating the error calibration procedure of the broadband resistive divider according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of an error calibration apparatus for a broadband resistive divider according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of an error calibration apparatus based on a 3458A broadband resistor divider according to an embodiment of the present invention;
fig. 5 is a schematic diagram of an error calibration apparatus based on 5922 wide-band resistor divider according to an embodiment of the present invention.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.
Fig. 3 shows a calibration arrangement for a broadband resistive divider according to the inventive concept. In the embodiment shown in fig. 3, the calibration device is composed of a multifunctional standard source (including an amplifier), two digital samplers with high stability options, a case and a controller, a high-precision digital sampling card, a signal generation card, a clock card, a control card, a wire, a computer and the like. In this embodiment, the digital sampler adopts a 3458A digital sampler, the casing is a PXIe casing, the high-precision digital sampling card is a PXI-5922 high-precision digital sampling card, the signal generation card is a PXI-5421 signal generation card, the clock card is a PXIe-6674T clock card, the control card is a GPIB control card, and the line is a GPIB line.
As shown in FIG. 4, in the calibration of the specific difference and angular difference of the broadband resistive voltage divider with frequencies of 50Hz, 400Hz and 1kHz, the calibration device of the low-frequency resistive voltage divider is composed of a multifunctional standard source (including an amplifier), two 3458A digital samplers with high stability selection parts, a PXIe case and a controller, a PXI-5421 signal generation card, a GPIB control card, a GPIB wire and a computer according to one embodiment of the invention. The PXIe case, the controller and the PXI-5421 signal generator are used as external trigger signals to control the two devices 3458A to perform synchronous sampling.
In another embodiment according to the present invention, as shown in fig. 5, when calibrating the specific and angular differences of the broadband resistive voltage divider with frequencies of 10kHz, 100kHz and 1MHz, the high-frequency resistive voltage divider calibration apparatus is composed of a multifunctional standard source (including an amplifier), a PXIe chassis and controller, a PXI-5922 high-precision digital sampling card, a PXIe-6674T clock card, a GPIB control card, a GPIB line and a computer. The clock generated by the PXIe-6674T clock card is used for replacing the internal sampling clock of the PXI-5922, and the sampling synchronization error of the PXI-5922 is reduced.
In one embodiment according to the present invention, the entire voltage divider is designed based on double power in order to improve the uncertainty of the index and calibration result of the voltage divider. Each voltage divider has a fixed voltage division ratio of 10, rated input voltages are respectively 2V, 4V, 8V, 16V, 32V, 64V, 120V, 240V, 480V and 1000V from large to small, output voltages are all 0.8V, high-range voltage is twice of low-range voltage, input impedance is 500-250 k omega, working current is 4mA, when the voltage divider is used, an adjustable capacitor box is connected behind a main voltage division part, and a 1:1 buffer amplifier is connected behind the main voltage division part for impedance conversion. The main characteristics of each voltage divider are shown in table 1.
Figure BDA0003391008590000091
Figure BDA0003391008590000101
TABLE 1 broadband resistive divider characteristics
After designing and constructing the resistor divider for a wide frequency band as described above according to the concept of the present invention, calibration is performed according to the following principles and concepts.
Because the output impedance of the broadband resistance voltage divider is large, a resistance of hundreds of ohms and a capacitance of dozens of picofarads to hundreds of picofarads generally exist, and if broadband alternating voltage measuring equipment is directly used for measurement, a large error is introduced. Thus, in one embodiment, a 1:1 buffer amplifier is back-terminated for impedance transformation in accordance with the concepts of the present invention. In this embodiment, the buffer amplifier is considered to be part of a resistor divider. On the basis, the resistor voltage division part, the capacitor box and the buffer amplifier are subjected to integral error calibration. Each voltage divider has a capacitor box matched with it and a buffer amplifier used fixedly.
In order to reduce the error introduced by different ranges of the digital sampler and reduce the non-linear error of the same range, in the embodiment, the input voltage of the broadband resistive divider is designed by twice, that is, the rated input voltage of one divider is twice the rated input voltage of the other divider, and the rated input voltage of the initial divider is reduced to 2V.
The voltage divider with the double-magnification design can be calibrated by a half-voltage load recursion method, namely a 2V/0.8V voltage divider is calibrated from the same 0.8V signal by means of a 3458A/PXI-5922 high-precision digital sampling system, then 4V/0.8V is calibrated under the half-load voltage by means of 2V/0.8V, after 4V/0.8V is determined, 8V/0.8V is calibrated under the half-load voltage, and the calibration is sequentially carried out to 480V/0.8V. In the calibration process, the CH0 channel is always used as a reference, and the CH1 channel is used as a measured channel. The calibration software adopts LabVIEW language programming, and the operation process is based on a non-whole period compensation algorithm. The 2V/0.8V calibration of the starting voltage divider is guaranteed by means of good linearity of the 3458A/PXI-5922 high-precision digital sampling system at a full scale point and a half scale point. The calibration procedure utilizes this natural criterion of a voltage ratio of 1:1 and a phase angle of 0 ° for the same signal.
Referring to fig. 1, the method for calibrating an error of a wideband resistor divider according to this embodiment includes:
s1, providing voltage signals of multiple levels for a broadband resistor voltage divider of multiple levels through multiple first channels and multiple second channels by using multiple multifunctional standard sources respectively;
s2, when a plurality of multifunctional standard sources provide voltage signals of each level, a first channel is provided with a previous-level broadband resistive voltage divider, and a second channel is provided with a current-level broadband resistive voltage divider;
s3, respectively receiving and sampling partial pressure signals of a plurality of first channels and partial pressure signals of a plurality of second channels by using a plurality of digital sampling systems;
and S4, obtaining the net specific difference and the net angular difference according to the specific difference and the angular difference of the partial pressure signals of the plurality of first channels and the specific difference and the angular difference of the partial pressure signals of the plurality of second channels.
The former-stage broadband resistor divider is a 2V broadband resistor divider, a 4V broadband resistor divider, an 8V broadband resistor divider, a 16V broadband resistor divider, a 32V broadband resistor divider, a 64V broadband resistor divider, a 120V broadband resistor divider, a 240V broadband resistor divider and a 480V broadband resistor divider. The broadband resistor divider at the present stage is a 4V broadband resistor divider, an 8V broadband resistor divider, a 16V broadband resistor divider, a 32V broadband resistor divider, a 64V broadband resistor divider, a 120V broadband resistor divider, a 240V broadband resistor divider, a 480V broadband resistor divider and a 1000V broadband resistor divider. The voltage signals output by the multifunctional standard source and used for the broadband resistor voltage divider are 0.8V, 2V, 4V, 8V, 16V, 32V, 64V, 120V, 240V and 480V. The first channel and the second channel are referred to as a CH0 channel and a CH1 channel, respectively.
Referring to fig. 2, the specific calibration steps are as follows:
step 1: and calibrating the zero point of the device. The multifunctional standard source outputs 0.8V voltage, is directly connected to CH0 and CH1 channels of a 3458A/PXI-5922 high-precision digital sampling system without a voltage divider, runs the system, records the specific difference and the angular difference obtained by testing at the moment, and corrects the zero point error of the system.
Step 2: the 2V voltage divider is calibrated. The multifunctional standard source outputs 0.8V voltage, and one path of the multifunctional standard source is directly connected to a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system without a voltage divider. And the other path of the signal passes through a 2V voltage divider, is accessed into a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system, runs the system, and records the specific difference and the angular difference obtained by the test at the moment, namely the specific difference and the angular difference of the 2V voltage divider.
And 3, step 3: the 4V voltage divider is calibrated. The multifunctional standard source outputs 2V voltage, and one path of the multifunctional standard source passes through a 2V voltage divider and is connected into a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system. And the other path of the signal passes through a 4V voltage divider and is accessed into a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system, the system is operated, the ratio difference and the angular difference obtained by the test at the moment are recorded, and the ratio difference and the angular difference of the 4V voltage divider can be obtained after the ratio difference and the angular difference of the 2V voltage divider are corrected.
And 4, step 4: the 8V voltage divider is calibrated. The multifunctional standard source outputs 4V voltage, and one path of the multifunctional standard source passes through a 4V voltage divider and is connected into a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system. And the other path of the signal passes through an 8V voltage divider and is accessed into a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system, the system is operated, the ratio difference and the angle difference obtained by the test at the moment are recorded, and the ratio difference and the angle difference of the 8V voltage divider can be obtained after the ratio difference and the angle difference of the 4V voltage divider are corrected.
And 5, step 5: the 16V voltage divider is calibrated. The multifunctional standard source outputs 8V voltage, and one path of the multifunctional standard source passes through an 8V voltage divider and is connected into a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system. And the other path of the signal passes through a 16V voltage divider and is connected into a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system, the system is operated, the ratio difference and the angle difference obtained by testing at the moment are recorded, and the ratio difference and the angle difference of the 16V voltage divider can be obtained after the ratio difference and the angle difference of the 8V voltage divider are corrected.
And 6, step 6: the 32V voltage divider is calibrated. The multifunctional standard source outputs 16V voltage, and one path of the multifunctional standard source passes through a 16V voltage divider and is connected into a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system. And the other path is connected to a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system through a 32V voltage divider, the system is operated, the ratio difference and the angle difference obtained by testing at the moment are recorded, and the ratio difference and the angle difference of the 32V voltage divider can be obtained after the ratio difference and the angle difference of the 16V voltage divider are corrected.
And 7, step 7: the 64V voltage divider is calibrated. The multifunctional standard source outputs 32V voltage, and one path of the multifunctional standard source passes through a 32V voltage divider and is connected into a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system. And the other path is connected to a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system through a 64V voltage divider, the system is operated, the ratio difference and the angle difference obtained by the test at the moment are recorded, and the ratio difference and the angle difference of the 64V voltage divider can be obtained after the ratio difference and the angle difference of the 32V voltage divider are corrected.
And 8, step 8: the 120V voltage divider is calibrated. The multifunctional standard source outputs 60V voltage, and one path of the voltage passes through a 64V voltage divider and is connected into a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system. And the other path is connected to a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system through a 120V voltage divider, the system is operated, the ratio difference and the angle difference obtained by the test at the moment are recorded, and the ratio difference and the angle difference of the 120V voltage divider can be obtained after the ratio difference and the angle difference of the 64V voltage divider are corrected.
Step 9: the 240V voltage divider is calibrated. The multifunctional standard source outputs 120V voltage, and one path of the multifunctional standard source passes through a 120V voltage divider and is connected into a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system. And the other path is accessed to a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system through a 240V voltage divider, the system is operated, the ratio difference and the angular difference obtained by the test at the moment are recorded, and the ratio difference and the angular difference of the 240V voltage divider can be obtained after the ratio difference and the angular difference of the 120V voltage divider are corrected.
Step 10: the 480V voltage divider is calibrated. The multifunctional standard source outputs 240V voltage, and one path of the voltage passes through a 240V voltage divider and is connected into a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system. And the other path is connected to a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system through a 480V voltage divider, the system is operated, the ratio difference and the angular difference obtained by the test at the moment are recorded, and the ratio difference and the angular difference of the 480V voltage divider can be obtained after the ratio difference and the angular difference of the 240V voltage divider are corrected.
And 11, step 11: the 1000V voltage divider is calibrated. The multifunctional standard source outputs 480V voltage, and one path of the multifunctional standard source passes through a 480V voltage divider and is connected into a CH0 channel of a 3458A/PXI-5922 high-precision digital sampling system. And the other path is connected to a CH1 channel of a 3458A/PXI-5922 high-precision digital sampling system through a 1000V voltage divider, the system is operated, the ratio difference and the angle difference obtained by the test at the moment are recorded, and the ratio difference and the angle difference of the 1000V voltage divider can be obtained after the ratio difference and the angle difference of the 480V voltage divider are corrected.
According to the inventive concept, the effects of non-integer period errors are taken into account during the calibration process and the non-integer periods are compensated for.
The inventive non-integer period compensation algorithm can be used for accurate measurement of alternating current signals. Compared with other algorithms in the prior art, the compensation algorithm provided by the invention still has higher measurement accuracy, and only 1-time fundamental wave result is input during calculation.
For the AC signal to be measured, if N sampling data are used for analysis, when NT issWhen MT, the sampling process is referred to as full-period sampling, where TsFor a sampling interval (sampling frequency f)s＝1/Ts) T is the period of the signal to be detected, and M is an integer; when NT issWhen not equal to MT, the sampling process is referred to as non-full-period sampling. For non-full-period sampling, when NT issWhen MT ═ Δ, Δ ≠ 0, and | Δ | < 1, it is called quasi-integer-period sampling, and more generally | Δ | < pi, which is called non-integer-period sampling. To improve the measurement accuracy of the ac sampling method, it is preferable to perform full-period sampling, but in practice, the frequency of the signal to be measured always varies within a certain range, and the period cannot be accurately determined, so that in practice, a digital sampling system cannot perform full-period sampling completely, and N pieces of sampling data cannot completely cover the period of M pieces of signal to be measured, that is, NTs-MT ═ Δ (here Δ is referred to as the non-whole period sample offset). The non-integer period compensation algorithm is to introduce the non-integer period sampling deviation delta obtained by calculation into a model and correct a primary result so as to obtain a more accurate secondary result.
For AC signals containing harmonics, the mathematical model is assumed to be
Figure BDA0003391008590000141
Where ω is the angular frequency, T is the period of the signal, K is the number of harmonics, a0In order to be a direct current component,
Figure BDA0003391008590000142
amplitude of the kth harmonic, arctan (a)k/bk) The phase of the k-th harmonic. Using a sampling interval of Ts(sampling frequency f)s＝1/Ts) The digital sampling system of (2) samples y (t), and a discrete signal is obtained:
Figure BDA0003391008590000143
and analyzing the discrete signals by adopting a certain digital signal processing algorithm to obtain the frequency, amplitude, phase and other parameters of each subharmonic.
For the time-domain continuous signal in equation (1), the parameters of the dc component and the nth harmonic are known as follows from the orthogonality of the trigonometric function and the fourier transform principle:
Figure BDA0003391008590000144
Figure BDA0003391008590000145
Figure 1
if the digital sampling system does a full-period sampling, NTsFor MT, then the orthogonality of trigonometric functions and the fourier transformation principle are the same
Figure BDA0003391008590000151
Figure BDA0003391008590000152
Figure BDA0003391008590000153
By adopting the non-integer-period sampling method, the non-integer-period sampling deviation reaches | Delta | less than 1, and the quasi-integer-period sampling is realized. Under quasi-whole-period sampling conditions, NTsMT + Δ. Still using the Fourier transform principle to analyze the harmonics, then
Figure BDA0003391008590000154
If it is
Figure BDA0003391008590000155
Then equation (10) can be written as
Figure BDA0003391008590000156
Similarly, the parameters of the nth harmonic can be described as follows:
Figure BDA0003391008590000161
Figure BDA0003391008590000162
the rewriting equations (11) to (13) are as follows:
Figure BDA0003391008590000163
the vector consisting of the direct current component and the true value of each harmonic component of the measured signal is assumed as follows:
A＝(a0,a1,a2,…,aK,b1,b2,…,bK)T (15)
under the condition of non-whole period sampling, the vector formed by estimated values of DC component and each subharmonic component obtained by utilizing Fourier transform principle is
Figure BDA0003391008590000164
Order to
Figure BDA0003391008590000171
According to the formula (14), the compound can be obtained
Figure BDA0003391008590000172
Obviously, if known, under non-full-period sampling conditions
Figure BDA0003391008590000173
And F, the direct current component and the harmonic component of the measured signal can be compensated by the following formula
Figure BDA0003391008590000174
The (2K +1) × (2K +1) -dimensional matrix F can in turn be written in the form
Figure BDA0003391008590000175
Wherein the content of the first and second substances,
F11＝1
F12＝(F21)T＝(β1,β2,…,βK)
F13＝(F31)T＝(α1,α2,…,αK)
Figure BDA0003391008590000176
Figure BDA0003391008590000177
Figure BDA0003391008590000178
Figure BDA0003391008590000179
the non-whole period sampling deviation delta is calculated by adopting an interpolation method: assuming that the sampling period corresponds to n + Δ, the end of the period is between n and n + l, and the starting point is sampling y0、y1Is the first sample point, and the two sample points near the expected end point are ynAnd yn+lIn addition to let y0At ynAnd yn+lLet y also interpolate in addition ton+1At y0 and ylInterpolation, the complement of the whole period sample Δ is given as:
Figure BDA0003391008590000181
the above description is only one embodiment of the present invention, and is not intended to limit the present invention, and it is apparent to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. An error calibration method for a broadband resistor divider comprises the following steps:
s1, providing voltage signals of multiple levels for the broadband resistor voltage divider of multiple levels through multiple first channels and multiple second channels by using multiple multifunctional standard sources respectively;
s2, when the multifunctional standard sources provide voltage signals of each level, the first channel is provided with a previous-level broadband resistive voltage divider, and the second channel is provided with a current-level broadband resistive voltage divider;
s3, receiving and sampling the partial pressure signals of the first channels and the partial pressure signals of the second channels by using a plurality of digital sampling systems respectively;
and S4, obtaining the net specific difference and the net angular difference according to the specific difference and the angular difference of the partial pressure signals of the plurality of first channels and the specific difference and the angular difference of the partial pressure signals of the plurality of second channels.
2. The method of claim 1, wherein prior to step S1, the digital sampling system is modified for zero point error by providing a voltage signal to the digital sampling system via a first channel and a second channel, respectively, using a multi-function standard source.
3. The method according to claim 1, wherein the step S3 further comprises: and in the process of respectively receiving and sampling the partial pressure signals of the plurality of first channels and the partial pressure signals of the plurality of second channels by using the plurality of digital sampling systems, compensating for the error of non-whole-period sampling of the plurality of digital sampling systems by using a non-whole-period compensation algorithm.
4. The method of claim 3, wherein the non-full-period compensation algorithm comprises:
establishing a mathematical model for the alternating current signals containing harmonic waves in the partial pressure signals, wherein the mathematical model comprises the following steps:
Figure FDA0003391008580000021
where ω is the angular frequency, T is the period of the divided signal, K is the number of harmonics, a0Is a direct current component, akAnd bkIs a harmonic component;
the digital sampling system is utilized to carry out non-whole period sampling on the alternating current signal to obtain a discrete signal, and the discrete signal is as follows:
Figure FDA0003391008580000022
wherein, the sampling chamberIs separated by Ts；
Processing the discrete signals by using a digital signal processing algorithm to obtain the frequency, amplitude and phase of each harmonic signal, wherein,
Figure FDA0003391008580000023
amplitude of the kth harmonic signal, arctan (a)k/bk) Is the phase of the kth harmonic signal;
obtaining the direct current component and each harmonic component of the voltage division signal according to the frequency, the amplitude and the phase, compensating by the following formula,
Figure FDA0003391008580000024
wherein A ═ a0,a1,a2,…,aK,b1,b2,…,bK)TA vector composed of a direct current component and a true value of each subharmonic component of the partial pressure signal is represented;
Figure FDA0003391008580000025
expressing vectors composed of estimated values of direct current components and each subharmonic component obtained by utilizing a Fourier transform principle under the non-whole period sampling condition;
Figure FDA0003391008580000026
Figure FDA0003391008580000031
calculating the non-integer-period sampling deviation by using an interpolation method, so that the non-integer-period sampling deviation meets the condition that | delta | is less than 1, and the complement of the whole-period sampling is as follows:
Figure FDA0003391008580000032
wherein, the sampling period is n + delta, the end point of the sampling period is between n and n + l, and the sampling point of the start point is y0，y1Is the first sample point, and the two sample points near the expected end point are ynAnd yn+l。
5. The method of claim 1, wherein the broadband resistive voltage divider comprises a resistive main voltage dividing portion, a capacitive box, and a buffer amplifier connected in series.
6. The method of claim 1, wherein the upper-level broadband resistor divider is 2V broadband resistor divider, 4V broadband resistor divider, 8V broadband resistor divider, 16V broadband resistor divider, 32V broadband resistor divider, 64V broadband resistor divider, 120V broadband resistor divider, 240V broadband resistor divider, or 480V broadband resistor divider;
the broadband resistor divider at the current stage is a 4V broadband resistor divider, an 8V broadband resistor divider, a 16V broadband resistor divider, a 32V broadband resistor divider, a 64V broadband resistor divider, a 120V broadband resistor divider, a 240V broadband resistor divider, a 480V broadband resistor divider and a 1000V broadband resistor divider.
7. The method of claim 1, wherein the voltage signal output by the multifunctional standard source and being the broadband resistor divider is 0.8V, 2V, 4V, 8V, 16V, 32V, 64V, 120V, 240V, and 480V.
8. An error calibration apparatus of a broadband resistor divider implemented by the error calibration method of the broadband resistor divider according to any one of claims 1 to 7, comprising: a multifunctional standard source, a first broadband resistive voltage divider, a second broadband resistive voltage divider, a first digital sampling system and a second digital sampling system,
the first broadband resistive voltage divider is provided with a first channel, and the second broadband resistive voltage divider is provided with a second channel;
the first broadband resistive divider is connected with the first digital sampling system through the first channel, and the second broadband resistive divider is connected with the second digital sampling system through the second channel;
the multifunctional standard source provides voltage signals for the first broadband resistive divider and the second broadband resistive divider through the first channel and the second channel, respectively.
9. The apparatus of claim 8, wherein the first digital sampling system and the second digital sampling system each comprise: 3458A digital sampling module, PXIe cabinet, controller, PXI-5421 signal generation module, GPIB control module and GPIB line,
the PXIe case, the controller and the PXI-5421 signal generation module jointly control two 3458A digital sampling modules to perform synchronous sampling;
the GPIB wire is used for connecting the 3458A digital sampling module, the PXIe case, the controller, the PXI-5421 signal generating module and the GPIB control module in sequence.
10. The apparatus of claim 8, wherein the first digital sampling system and the second digital sampling system each comprise: a PXI-5922 digital sampling module, a PXIe-6674T clock module, a GPIB control module, a GPIB wire, a PXIe case and a controller,
the PXIe-6674T clock module is used for enabling the sampling time interval of the two PXI-5922 digital sampling modules to be more accurate;
the GPIB wire connects the PXI-5922 digital sampling module, the PXIe case, the controller, the PXIe-6674T clock module and the GPIB control module in sequence.
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