A system and method for improving the accuracy of high-frequency sinusoidal current measurement by resistance

Abstract

The present application provides a system and method for improving the accuracy of high-frequency sinusoidal current measurement by resistance. The system includes: a signal generator for emitting a high-frequency sinusoidal voltage signal of a set frequency, a device to be tested connected to the output end of the signal generator, a current measuring resistor connected in series with the device to be tested for detecting the current passing through the device to be tested, an oscilloscope electrically connected to both ends of the current measuring resistor via a probe or an interface for measuring the terminal current of the current measuring resistor, a computer connected to the data output end of the oscilloscope via a data line or a wireless transmission method for receiving the terminal current measured by the oscilloscope, and performing data processing and current correction calculations, receiving data from the oscilloscope via a computer, and using a data processing module to execute a discrete Fourier transform algorithm to calculate the amplitude and phase angle at the set test signal frequency, and based on the established impedance model of the current measuring resistor, a current correction module in the computer will perform phase and amplitude compensation on the measured current.

Description

Technical Field

[0001] The invention relates to a system and a method for improving the accuracy of measuring high-frequency sinusoidal current by resistance, and belongs to the field of power and electronic measurement. Background Art

[0002] In electrical measurement, the commonly used current measurement methods include current transformers, Hall current sensors, magnetoresistive current sensors and resistors. However, this method has certain limitations. For example, the measurement bandwidth of current transformers, Hall current sensors and magnetoresistive current sensors is basically lower than 10MHz, which is difficult to meet the needs of high-frequency sinusoidal current measurement; and the price of high-bandwidth current measuring resistors is also very expensive, which greatly increases the difficulty and cost of high-bandwidth current measurement.

[0003] In order to solve this problem, the present application proposes a measurement system and a measurement method for accurately measuring high-frequency sinusoidal current using a low-bandwidth current measuring resistor. This system and a method can realize accurate measurement of high-bandwidth AC current using a low-bandwidth current measuring resistor, and has important practical value in the field of power and electronic measurement. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a system and method for improving the accuracy of high-frequency sinusoidal current measurement using resistors, so as to solve the problems that the existing current measurement methods are difficult to meet the needs of high-frequency sinusoidal current measurement and the high price of high-bandwidth current measuring resistors.

[0005] In order to achieve the above object, the present invention is implemented by the following technical solution: a system for improving the accuracy of high-frequency sinusoidal current measurement by resistance, characterized in that: the system comprises:

[0006] A signal generator, the signal generator is used to emit a high-frequency sinusoidal voltage signal of a set frequency;

[0007] The device under test has an impedance of Z DUT , connected to the output end of the signal generator;

[0008] A current measuring resistor, which is connected in series with the device to be tested and is used to detect the current passing through the device to be tested;

[0009] An oscilloscope, the oscilloscope is electrically connected to the two ends of the current measuring resistor through a probe or an interface, and is used to measure the terminal voltage V of the current measuring resistor R ;

[0010] A computer is connected to the data output terminal of the oscilloscope via a data line or wireless transmission mode, and is used to receive the terminal voltage V measured by the oscilloscope. R , and perform data processing and current correction calculations.

[0011] Furthermore, the computer includes a data processing module and a current correction module.

[0012] The data processing module is used to execute the discrete Fourier transform algorithm and calculate the steady-state terminal voltage of the current measuring resistor at the test signal frequency ƒ s The amplitude at |V S | and phase angle ∠V S ,

[0013] The current correction module is based on the established current measuring resistor impedance model Z R , correct the AC current flowing through the current measuring resistor to obtain a certain current I R .

[0014] Furthermore, the impedance model Z of the current measuring resistor R The method uses an impedance analyzer to measure the curve data of the impedance of the current measuring resistor changing with the measuring frequency, and combines the data fitting method to establish a high-frequency impedance model of the current measuring resistor.

[0015] Furthermore, in order to ensure that the current I R The accuracy of the oscilloscope sampling frequency ƒ o Greater than or equal to the test sinusoidal voltage frequency ƒ s ten times, that is, satisfying the inequality .

[0016] Furthermore, in order to accurately correct the frequency of the current measuring resistor, the highest frequency ƒ when the impedance analyzer measures the impedance of the current measuring resistor i Greater than or equal to the test sinusoidal voltage frequency ƒ s ten times, that is, satisfying the inequality .

[0017] Furthermore, the correction formula used in the current correction module is |I R |=|V R | / |Z R | and ∠I R =∠V R -∠Z R .

[0018] Furthermore, the correct current I flowing through the current measuring resistor is calculated by the correction formula R At the test signal frequency ƒ s After the amplitude and phase angle at the compensation point are calculated, the high-frequency sinusoidal current I is reconstructed in the time domain according to the compensated current amplitude and phase angle. R Time domain waveform.

[0019] Furthermore, the time domain reconstructs the accurate sinusoidal current to be measured I R The calculation formula is , where the time variable t starts from 0 and lasts for a time equal to the time length corresponding to the sampling window.

[0020] A method for improving the accuracy of high-frequency sinusoidal current measurement by resistance, characterized in that the method comprises the following steps:

[0021] S1: using an impedance analyzer to measure the high-frequency impedance characteristic curve of the current measuring resistor, and storing the data in a data storage unit of the impedance analyzer;

[0022] S2: Input the test parameters into the computer, including the test sinusoidal voltage frequency ƒ s ;

[0023] S3: Use an oscilloscope to measure the terminal voltage V of the current measuring resistor R and transmit the measurement data to a data processing module in a computer system;

[0024] S4: In the data processing module, according to the sampling frequency ƒ0 of the oscilloscope, the discrete Fourier transform algorithm is used to calculate the steady-state terminal voltage of the current measuring resistor under the test signal ƒ s The amplitude at |V S | and phase angle ∠V S ;

[0025] S5: Based on the established current measuring resistor impedance model Z R , correct the AC current flowing through the current measuring resistor to obtain the accurate current I R , and then reconstruct the measured high-frequency sinusoidal current I in the time domain based on the compensated current amplitude and phase angle R The time domain waveform.

[0026] The beneficial effects of the present invention are:

[0027] The method of the present application uses a high-bandwidth impedance analyzer to measure the high-frequency impedance characteristic curve of the current measuring resistor, and establishes a high-frequency impedance model of the current measuring resistor based on this data, thereby ensuring the key to subsequent measurement accuracy. Then, an oscilloscope is used to measure the terminal voltage of the current measuring resistor connected in series with the device to be tested. According to the measurement results, a computer is used to perform offline calculations to extract the amplitude and phase information of the terminal voltage. In this process, the computer receives data from the oscilloscope, and uses the data processing module to execute the discrete Fourier transform algorithm to accurately calculate the amplitude and phase angle at the set test signal frequency. Finally, based on the established current measuring resistor impedance model, the current correction module in the computer will compensate the measured current for phase and amplitude. Through the above steps, the present application not only improves the measurement accuracy, but also reduces the cost, making the measurement of high-frequency sinusoidal current more cost-effective. This method has broad application prospects in the fields of power and electronic measurement, and can bring significant technological progress and economic benefits to related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0029] Figure 1 A schematic diagram of the connection structure of a system and method for improving the accuracy of high-frequency sinusoidal current measurement by resistance according to the present invention;

[0030] Figure 2 The schematic diagram of the structure of the high-frequency impedance model of the current measuring resistor measured by the impedance analyzer;

[0031] Figure 3 A schematic diagram of a structure for reconstructing a measured high-frequency sinusoidal current in the time domain based on the compensated current amplitude and phase angle;

[0032] Figure 4 The present invention is a flow chart of a system and method for improving the accuracy of high-frequency sinusoidal current measurement by resistance.

[0033] The reference numerals are: 1. signal generator; 2. device to be tested; 3. current measuring resistor; 4. oscilloscope; 5. computer. DETAILED DESCRIPTION

[0034] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0035] [A system for improving the accuracy of high-frequency sinusoidal current measurement by resistance according to the present invention]

[0036] Figure 1 The figure is a schematic diagram of the connection structure of a system and method for improving the accuracy of high-frequency sinusoidal current measurement by resistance according to the present invention. Figure 1 As shown, the present invention provides a technical solution for a system for improving the accuracy of high-frequency sinusoidal current measurement by resistance: the system comprises:

[0037] A signal generator 1, wherein the signal generator 1 is used to emit a high-frequency sinusoidal voltage signal of a set frequency;

[0038] The impedance of the device under test 2 is Z DUT , connected to the output end of the signal generator 1;

[0039] A current measuring resistor 3, which is connected in series with the device under test 2 and is used to detect the current passing through the device under test 2;

[0040] An oscilloscope 4, which is electrically connected to both ends of the current measuring resistor 3 through a probe or an interface, and is used to measure the terminal voltage V of the current measuring resistor 3 R ;

[0041] Computer 5, the computer 5 is connected to the data output terminal of oscilloscope 4 through a data line or wireless transmission mode, and is used to receive the terminal voltage V measured by oscilloscope 4 R , and perform data processing and current correction calculations.

[0042] In order to perform accurate calculations, the computer 5 includes a data processing module and a current correction module.

[0043] The data processing module is used to execute the discrete Fourier transform algorithm and calculate the steady-state terminal voltage of the current measuring resistor 3 at the test signal frequency ƒ s The amplitude at |V S | and phase angle ∠V S ,

[0044] The current correction module is based on the established current measuring resistor 3 impedance model Z R , correct the AC current flowing through the current measuring resistor 3 to obtain a certain current I R .

[0045] [According to the present invention, an impedance analyzer is used to measure and establish a high-frequency impedance model of the current measuring resistor]

[0046] Figure 2 This is a schematic diagram of the structure of using an impedance analyzer to measure and establish a high-frequency impedance model of the current measuring resistor. Figure 2 As shown, in order to ensure the accuracy of subsequent measurements, the present invention also provides a system for improving the accuracy of high-frequency sinusoidal current measurement by resistance. The impedance model Z of the current measuring resistor 3 is R The impedance analyzer is used to measure the curve data of the impedance change of the current measuring resistor 3 with the measuring frequency, and the high-frequency impedance model of the current measuring resistor is established by combining the data fitting method.

[0047] To avoid signal aliasing, and to ensure that the current I R The accuracy of the oscilloscope sampling frequency ƒ o Greater than or equal to the test sinusoidal voltage frequency ƒ s ten times.

[0048] In order to ensure the accuracy of the model and to accurately correct the frequency of the current measuring resistor 3, the highest frequency when the impedance analyzer measures the impedance of the current measuring resistor 3 is ƒ i Greater than or equal to the test sinusoidal voltage frequency ƒ s ten times.

[0049] In order to improve the measurement accuracy, the correction formula used in the current correction module is |I R |=|V R | / |Z R | and ∠I R=∠V R -∠Z R .

[0050] [Structure of reconstructing the measured high-frequency sinusoidal current in the time domain based on the compensated current amplitude and phase angle]

[0051] Figure 3 The schematic diagram of the structure of high-frequency sinusoidal current measured in the time domain based on the compensated current amplitude and phase angle is shown in Figure 1. Figure 3 As shown, in order to reconstruct the high-frequency sinusoidal current, the present invention also provides a system for improving the accuracy of high-frequency sinusoidal current measurement by resistance, and the accurate current I flowing through the current measuring resistor 3 is calculated by the correction formula R At the test signal frequency ƒ s After the amplitude and phase angle at the compensation point are calculated, the high-frequency sinusoidal current I is reconstructed in the time domain according to the compensated current amplitude and phase angle. R Time domain waveform.

[0052] In order to realize the calculation of accurate sinusoidal current, the time domain reconstructs the accurate sinusoidal current to be measured I R The calculation formula is , where the time variable t starts from 0 and lasts for a time equal to the time length corresponding to the sampling window.

[0053] [A system and method for improving the accuracy of high-frequency sinusoidal current measurement by resistance according to the present invention]

[0054] Figure 4 The figure is a flow chart of a system and method for improving the accuracy of high-frequency sinusoidal current measurement by resistance according to the present invention. Figure 4 As shown, in order to achieve accurate measurement of high-bandwidth AC current by a low-bandwidth current measuring resistor, the present invention provides a method for improving the accuracy of high-frequency sinusoidal current measurement by a resistor, characterized in that the method comprises the following steps:

[0055] S1: Use an impedance analyzer to measure the high-frequency impedance characteristic curve of the current measuring resistor 3, and store the data in a data storage unit of the impedance analyzer;

[0056] S2: Input the test parameters into computer 5, including the test sinusoidal voltage frequency ƒ s ;

[0057] S3: Use an oscilloscope to measure the terminal voltage V of current measuring resistor 3 R and transmit the measured data to a data processing module in the computer 5 system;

[0058] S4: In the data processing module, according to the sampling frequency ƒ0 of the oscilloscope, the discrete Fourier transform algorithm is used to calculate the steady-state terminal voltage of the current measuring resistor 3 under the test signal ƒ s The amplitude at |VS | and phase angle ∠V S ;

[0059] S5: Based on the established current measuring resistor 3 impedance model Z R , correct the AC current flowing through the current measuring resistor 3 to obtain the accurate current I R , and then reconstruct the measured high-frequency sinusoidal current I in the time domain based on the compensated current amplitude and phase angle R The time domain waveform.

[0060] [Instructions for use of a system and method for improving the accuracy of high-frequency sinusoidal current measurement by resistance according to the present invention]

[0061] The method of the present application uses a high-bandwidth impedance analyzer to measure the high-frequency impedance characteristic curve of the current measuring resistor, and establishes a high-frequency impedance model of the current measuring resistor based on this data, thereby ensuring the key to subsequent measurement accuracy. Then, an oscilloscope is used to measure the terminal voltage of the current measuring resistor connected in series with the device to be tested. According to the measurement results, a computer is used to perform offline calculations to extract the amplitude and phase information of the terminal voltage. In this process, the computer receives data from the oscilloscope, and uses the data processing module to execute the discrete Fourier transform algorithm to accurately calculate the amplitude and phase angle at the set test signal frequency. Finally, based on the established current measuring resistor impedance model, the current correction module in the computer will compensate the measured current for phase and amplitude. Through the above steps, the present application not only improves the measurement accuracy, but also reduces the cost, making the measurement of high-frequency sinusoidal current more cost-effective. This method has broad application prospects in the fields of power and electronic measurement, and can bring significant technological progress and economic benefits to related industries.

[0062] The embodiments are as follows: a signal generator capable of generating a sinusoidal voltage signal with a frequency up to 100 MHz is selected; an oscilloscope is used to adjust the sampling frequency to 1 GHz for measuring the terminal voltage of the current measuring resistor; an impedance analyzer having a maximum measurement frequency of not less than 1 GHz is used to measure the high-frequency impedance characteristics of the current measuring resistor; and a device to be tested includes a capacitor C0 connected in series with a parasitic resistor ESR, wherein ESR=5 mΩ, C0=1 uF, a current measuring resistor R having a resistance value of 0.1 Ω, and an inductor L=10 nH connected in series with the current measuring resistor, that is, the high-frequency impedance of the current measuring resistor is composed of a resistor R and a parasitic inductor L connected in series.

[0063] Among them, the expression formula for testing AC sinusoidal signal is: , test frequency f s =100MHz, the amplitude of the sinusoidal voltage is 0.1V, and the impedance model of the current measuring resistor is: , where ω represents the angular frequency of the sinusoidal current flowing through the measuring resistor, and j is an imaginary unit.

[0064] After the signal source, the device under test and the current measuring resistor are simulated, the voltage at the current measuring resistor terminal is sampled at a sampling rate of 1 GHz after the system reaches a steady state. The voltage at the current measuring resistor terminal is equal to the sum of the voltage drop on the current measuring resistor and the voltage drop on its parasitic inductance. At the same time, the actual current I flowing through the current measuring resistor is real Sampling is performed to compare the current with the corrected current to verify the correctness of the correction algorithm.

[0065] If the voltage across the resistor is directly divided by the resistance of the resistor, the current I flowing through the resistor can be calculated. R1 However, since the existence of the current measuring resistor and inductor is not taken into account, the measured I R1 and the actual current I real There is a large amplitude and phase deviation between them. This is because the inductive reactance of the parasitic inductance L of the current measuring resistor is much larger than the resistance value of the current measuring resistor at high frequency. If the calibration method is not adopted, it is impossible to use an ordinary current measuring resistor to measure high-frequency sinusoidal current.

[0066] Therefore, the present invention measures the terminal voltage V R The data is imported into the computer and processed using the discrete Fourier transform algorithm to obtain the terminal voltage amplitude at 100MHz |V RL1 |=0.1V and phase φ V1 =-0.9417 radians. The correction formula according to the present invention can calculate the corrected amplitude of the 100MHz sinusoidal current flowing through the current measuring resistor |I R11 | and phase φ R11 , specifically: , substituting R=0.1,L=10nH into |I R11 |=0.0159A,φ R11 =-2.47 radians. According to the correction formula proposed in the present invention, the current time domain waveform I can be reconstructed from the compensated current amplitude and phase. R11 and the actual current I real for comparison.

[0067] After calibration, the current I flowing through the current measuring resistor R11 The values ​​at each sampling point are consistent with the actual current I real The same proves the accuracy of the calibration algorithm and time domain reconstruction method proposed in the present invention for realizing high-frequency sinusoidal current measurement through current measuring resistor. The specific numerical results are as follows: Before calibration, the current measuring resistor current IR1 is different from the actual current I real The amplitude deviation is 50%, and the phase deviation is 1.57 radians. After correction, the current I R11 The actual current I real The amplitude deviation is less than 1%, and the phase deviation is less than 0.1 radian.

[0068] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0069] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A system for improving the accuracy of high-frequency sinusoidal current measurement by resistance, characterized in that: The system comprises: A signal generator (1), the signal generator (1) being used to emit a high-frequency sinusoidal voltage signal of a set frequency; The device under test (2) has an impedance of Z DUT , connected to the output end of the signal generator (1); A current measuring resistor (3), the current measuring resistor (3) being connected in series with the device to be tested (2) and being used to detect a current passing through the device to be tested (2); An oscilloscope (4), the oscilloscope (4) being electrically connected to the two ends of the current measuring resistor (3) through a probe or an interface, and being used to measure the terminal voltage V of the current measuring resistor (3) R ; A computer (5), the computer (5) being connected to the data output terminal of the oscilloscope (4) via a data line or a wireless transmission mode, and being used for receiving the terminal voltage VR measured by the oscilloscope (4), and performing data processing and current correction calculation; The computer (5) comprises a data processing module and a current correction module. The data processing module is used to execute a discrete Fourier transform algorithm and calculate the amplitude |VS| and phase angle ∠VS of the steady-state terminal voltage of the current measuring resistor (3) at the test signal frequency fs. The current correction module corrects the alternating current flowing through the current measuring resistor (3) based on the established impedance model ZR of the current measuring resistor (3) to obtain a determined current IR; The correction formulas used in the current correction module are |IR|=|VR| / |ZR| and ∠IR=∠VR-∠ZR; After the amplitude and phase angle of the accurate current IR flowing through the current measuring resistor (3) at the test signal frequency fs are calculated by the correction formula, the time domain waveform of the high-frequency sinusoidal current IR is reconstructed in the time domain according to the compensated current amplitude and phase angle; The calculation formula for accurately reconstructing the sinusoidal current IR to be measured in the time domain is: R =|I R |×cos(2πf s t+∠I R ), where the time variable t starts from 0 and lasts for a time equal to the time length corresponding to the sampling window.

2. A system for improving the accuracy of high-frequency sinusoidal current measurement by resistance according to claim 1, characterized in that: The impedance model Z of the current measuring resistor (3) is R The method uses an impedance analyzer to measure the curve data of the impedance of the current measuring resistor (3) changing with the measuring frequency, and combines the data fitting method to establish a high-frequency impedance model of the current measuring resistor (3).

3. A system for improving the accuracy of high-frequency sinusoidal current measurement by resistance according to claim 2, characterized in that: In order to ensure that the current I R The accuracy of the oscilloscope sampling frequency f o Greater than or equal to the test sinusoidal voltage frequency f s ten times.

4. A system for improving the accuracy of high-frequency sinusoidal current measurement by resistance according to claim 3, characterized in that: In order to accurately correct the frequency measured by the current measuring resistor (3), the impedance analyzer measures the impedance of the current measuring resistor (3) at the highest frequency f i Greater than or equal to the test sinusoidal voltage frequency f s ten times.

5. A method for improving the accuracy of high-frequency sinusoidal current measurement by resistance, characterized in that: The method is applied to the system for improving the accuracy of high-frequency sinusoidal current measurement by resistance as claimed in any one of claims 1 to 4, and the method comprises the following steps: S1: using an impedance analyzer to measure the high-frequency impedance characteristic curve of the current measuring resistor (3), and storing the data in a data storage unit of the impedance analyzer; S2: Input the test parameters into the computer (5), including the test sinusoidal voltage frequency f s ; S3: Use an oscilloscope to measure the terminal voltage V of the current measuring resistor (3) R and transmit the measured data to a data processing module in a computer (5) system; S4: In the data processing module, according to the sampling frequency f0 of the oscilloscope, the discrete Fourier transform algorithm is used to calculate the steady-state terminal voltage of the current measuring resistor (3) under the test signal f s The amplitude at |V S | and phase angle ∠V S ; S5: Based on the established current measuring resistor (3) impedance model Z R , correct the AC current flowing through the current measuring resistor (3) to obtain the accurate current I R , and then reconstruct the measured high-frequency sinusoidal current I in the time domain based on the compensated current amplitude and phase angle R The time domain waveform.

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