Wide-range multichannel high-resistance tester

Abstract

The invention relates to a wide-range multichannel high-resistance tester, which belongs to the technical field of electronic measurement, and is characterized in that each measurement channel is connected with a resistor to be measured; the upper computer executes measurement control and data processing on the wide-range multi-channel high-resistance tester; the ARM processor sends the test instruction to the FPGA processor; the FPGA processor is used for controlling the wide-range switching module and the channel switching module; the channel switching module is used for switching a measurement channel needing to be measured; each current sampling unit collects a current signal of the to-be-measured resistor passing through the corresponding measurement channel; the range switching module adopts a self-adaptive range switching algorithm to select an optimal range; the amplification circuit amplifies the current test signal; the ADC module converts the amplified current test signal into a current digital signal; and the FPGA processor calculates the resistance value of the resistor to be measured on the corresponding measurement channel according to the current digital signal. The invention has the characteristics of wide measuring range, high efficiency and high stability.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic measurement, and in particular relates to a wide-range multi-channel high-resistance tester. Background Art

[0002] High Voltage Insulation Resistance Tester (High Voltage Insulation Resistance Tester, referred to as high resistance tester), this instrument is suitable for measuring the insulation resistance of various transformers, motors, cables, switches, electrical equipment and insulating materials.

[0003] The existing high resistance tester has the following problems:

[0004] 1. Traditional high-resistance testers have a limited range (usually 10^6 to 10^12Ω), making it difficult to cover ultra-low resistance (<1MΩ) and ultra-high resistance (>10^15Ω) measurement requirements.

[0005] 2. The single-channel design is inefficient and cannot meet the requirements of multi-sample parallel testing scenarios.

[0006] 3. High resistance measurement is susceptible to environmental interference (temperature, humidity, electromagnetic noise), and existing equipment has insufficient anti-interference capabilities.

[0007] 4. Low degree of automation, relying on manual switching of measuring range or calibration.

[0008] In summary, existing high resistance testers have defects such as narrow range, low efficiency, poor stability, and low degree of automation. Summary of the Invention

[0009] In view of the above deficiencies in the prior art, an object of the present invention is to provide a wide-range multi-channel high-resistance tester having the characteristics of wide range, high efficiency and high stability.

[0010] The present invention proposes a wide-range multi-channel high-resistance tester, comprising: a host computer, an ARM processor, an FPGA processor, an analog-to-digital conversion ADC module, an amplifier circuit, a range switching module, a current sampling module, a channel switching module, multiple measurement channels and a protection resistor module, wherein:

[0011] Each measurement channel is connected to a resistor to be measured, and the protection resistor module includes multiple protection resistors, each protection resistor is connected to a corresponding measurement channel;

[0012] The host computer is used to perform measurement control and data processing on the wide-range multi-channel high-resistance tester; the host computer sends a test instruction to the ARM processor;

[0013] The ARM processor is used to convert the test instruction into a format instruction suitable for the FPGA processor, and send the converted test instruction to the FPGA processor;

[0014] The FPGA processor controls the wide-range switching module and the channel switching module according to the test instruction to control the measurement channel;

[0015] The channel switching module is used to switch the measurement channel required for measurement under the control of the FPGA processor;

[0016] The current sampling module includes a plurality of current sampling units, each current sampling unit is used to collect the current signal of the resistance to be measured passing through the corresponding measurement channel;

[0017] The range switching module is used to select an optimal range according to the real-time current signal using an adaptive range switching algorithm, and output a current test signal according to the optimal range;

[0018] The amplifier circuit is used to amplify the current test signal;

[0019] The analog-to-digital conversion (ADC) module is used to convert the amplified current test signal into a current digital signal and send it to the FPGA processor; the FPGA processor calculates the resistance value of the resistor to be measured on the corresponding measurement channel based on the current digital signal.

[0020] Furthermore, when the resistance of the resistor to be measured is less than a minimum value of measurement, the protection resistor limits the current flowing through the corresponding measurement channel to protect the entire system.

[0021] Furthermore, the channel switching module switches in sequence under the control of the FPGA processor to test each measurement channel in sequence.

[0022] Furthermore, the amplifying circuit adopts a low-noise preamplifier, and the analog-to-digital conversion ADC module adopts a 24-bit ADC chip that supports dynamic baseline calibration.

[0023] Furthermore, the range switching module adopts a binary approximation method to select a range for testing.

[0024] Furthermore, the range switching module initially uses the preset default interval range [I_min, I_max] to test the current signal, and then takes the midpoint value range I_mid of the default interval for measurement;

[0025] Detect the output current signal measurement value. When the current signal measurement value is lower than the lower limit of the range, reduce the range to [I_min, I_mid]. When the current signal measurement value is higher than 90% FS, reduce the range to [I_mid, I_max]. When the current signal measurement value is in the ideal linear region, stop the iteration.

[0026] When the following convergence conditions are met, the output current signal measurement value is used as the current test signal:

[0027] The ratio of the current signal measurement value to the upper limit of the range is less than or equal to 2; or the maximum number of iterations is reached;

[0028] FS is the maximum measuring range.

[0029] Furthermore, the channel switching module adopts a multi-channel analog switch to switch the corresponding measurement channels under the multi-channel timing control of the FPGA processor.

[0030] Furthermore, it also includes: a calibration resistance matrix, which is connected to the FPGA processor and each measurement channel and is used to perform automatic calibration on each measurement channel under the control of the FPGA processor.

[0031] Furthermore, the calibration resistor matrix includes multiple standard resistors and a resistor matrix switching unit, each standard resistor is connected to a measurement channel respectively, and the resistor matrix switching unit is used to calibrate the corresponding measurement channel through the standard resistor under the control of the FPGA processor.

[0032] Furthermore, it also includes: a precision voltage source for providing a positive power supply during resistance testing.

[0033] The beneficial effects of the present invention are as follows:

[0034] 1. The wide-range multi-channel high-resistance tester of the present invention achieves a 1000-fold increase in range coverage (1kΩ to 10^16Ω) with a relative error of <±0.5%.

[0035] 2. The multi-channel parallel measurement efficiency of the wide-range multi-channel high-resistance tester of the present invention is increased by more than 10 times.

[0036] 3. The temperature drift compensation of the wide-range multi-channel high-resistance tester of the present invention enables the stability to reach ±0.1% / °C.

[0037] 4. The wide-range multi-channel high-resistance tester of the present invention adopts an adaptive range switching algorithm to dynamically select the optimal range according to the real-time current value, avoiding manual switching.

[0038] 5. The wide-range multi-channel high-resistance tester of the present invention realizes multi-channel synchronous calibration and automatically calibrates the gain error of each channel regularly through the built-in reference resistor matrix. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The accompanying drawings are only for the purpose of illustrating specific embodiments and are not to be considered as limiting the present invention. Throughout the drawings, the same reference numerals represent the same components. Obviously, the drawings described below are only some of the embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings.

[0040] Figure 1 This is a structural block diagram of a wide-range multi-channel high-resistance tester according to an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of the flow of measurement control and data processing performed by a host computer according to an embodiment of the present invention;

[0042] Figure 3 Flowchart of the adaptive range switching algorithm according to an embodiment of the present invention;

[0043] Figure 4 This is a flow chart of channel synchronization calibration according to an embodiment of the present invention;

[0044] Figure 5 This is a flow chart of range switching according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the technical solutions in the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are part of the embodiments of the present invention, rather than all of the embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work should fall within the scope of protection of the present invention.

[0046] Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concepts disclosed in the present invention.

[0047] In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the internal parts of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, like numbers in different figures represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of methods and systems consistent with certain aspects of the present invention, as detailed in the appended claims.

[0049] This invention proposes a wide-range, multi-channel high-resistance tester suitable for measuring high resistance values. It can be widely used for precision measurement in fields such as material insulation resistance and semiconductor impedance. This wide-range, multi-channel high-resistance tester features a wide measurement range (1 kΩ to 10^16 Ω), multi-channel measurement, and high precision, addressing the narrow range, low efficiency, and poor stability of existing equipment.

[0050] like Figure 1 As shown, the present invention proposes a wide-range multi-channel high-resistance tester, including: a host computer 1, an ARM processor 2, an FPGA processor 3, an analog-to-digital conversion ADC module 4, an amplification module 5, a range switching module 6, a current sampling module, a channel switching module 7, multiple measurement channels and a protection resistor module.

[0051] Specifically, the present invention supports multiple high-impedance input channels, each of which is equipped with an independent protection circuit and filter network. Each measurement channel is connected to a resistor to be measured.

[0052] The protection resistor module includes multiple protection resistors, each connected to a corresponding measurement channel. For example, if there are N measurement channels, they are: measurement channel 1, measurement channel 2, ... measurement channel N; protection resistor 1, protection resistor 2, ... protection resistor N; and resistor under test 1, resistor under test 2, ... resistor under test N. Measurement channel 1's two ends are connected to protection resistor 1 and resistor under test 1, respectively, and so on. An external power supply applies voltage to the resistor under test, and current is transmitted through the measurement channels.

[0053] The wide-range multi-channel high-resistance tester of the present invention further comprises: a precision voltage source 9 for providing a positive power supply during resistance testing.

[0054] When the protection resistor detects that the resistance of the corresponding resistor to be measured is less than the minimum value of the measurement, it limits the current flowing through the corresponding measurement channel to protect the entire system.

[0055] The host computer 1 is responsible for controlling the entire measurement control and data processing.

[0056] Specifically, the host computer 1 is used to perform measurement control and data processing for the wide-range multi-channel high-resistance tester. The host computer 1 sends a test instruction to the ARM processor 2.

[0057] ARM processor 2 is responsible for data processing and communication. ARM processor 2 is used to convert test instructions into instructions in a format suitable for FPGA processor 3 and send the converted test instructions to FPGA processor 3. ARM processor 2 is responsible for communicating with host computer 1 and transmitting the data collected by ADC module 4 to host computer 1.

[0058] FPGA implements multi-channel timing control. FPGA processor 3 controls wide range switching module 6 and channel switching module 7 according to the test instruction to control the measurement channel. That is, FPGA is responsible for controlling the measurement channel through the multi-way analog switch. Figure 2 .

[0059] The wide-range multi-channel high-resistance tester of the present invention further includes: a calibration resistor matrix 8, which is connected to the FPGA processor 3 and each measurement channel and is used to perform automatic calibration on each measurement channel under the control of the FPGA processor 3.

[0060] The calibration resistor matrix 8 enables simultaneous multi-channel calibration, automatically calibrating each channel's gain error periodically. The built-in standard resistor matrix can be set for pre-test calibration, minimizing the impact of the test environment on test results.

[0061] like Figure 4As shown, calibration resistor matrix 8 includes multiple standard resistors and a resistor matrix switching unit. Each standard resistor is connected to a measurement channel. For example, N measurement channels are connected: standard resistor 1, standard resistor 2, ..., standard resistor N. Precision voltage source 9 provides positive power to the standard resistors.

[0062] The resistance matrix switching unit is used to calibrate the corresponding measurement channel using a standard resistor under the control of the FPGA processor 3. The measurement negative electrode is connected to the resistance matrix switching unit and the resistance measurement channel respectively.

[0063] The channel switching module 7 is used to switch the measurement channel required for measurement under the control of the FPGA processor 3.

[0064] refer to Figure 2 The channel switching module 7 uses a multi-channel analog switch to switch the corresponding measurement channel under the multi-channel timing control of the FPGA processor 3. That is, the switching of the measurement channel is achieved by the multi-channel analog switch.

[0065] The channel switching module 7 switches each measurement channel in sequence under the control of the FPGA processor 3, thereby realizing testing of each measurement channel in sequence.

[0066] The current sampling module includes multiple current sampling units, each of which is used to collect the current signal of the resistor to be measured passing through the corresponding measurement channel.

[0067] The range switching module 6 is used to select the optimal range according to the real-time current signal using an adaptive range switching algorithm and output a current test signal according to the optimal range. The adaptive range switching algorithm dynamically selects the optimal range according to the real-time current value, avoiding manual switching.

[0068] refer to Figure 3 As shown in the figure, the binary approximation method can quickly lock in the optimal measurement range. First, the maximum range is used to test the current type. Then, the range is determined to be within the corresponding range M of the set range 1-N. If so, the current value is tested within range M. Then, the actual test value is determined to be within range M. If so, the test value is output. Otherwise, the range H is reselected according to the test value and the test is continued.

[0069] In the embodiment of the present invention, the adaptive range switching algorithm of the range switching module 6 adopts a binary approximation method to select a range for testing. Figure 5 As shown, first measure within the default range, then select the midpoint of the range for measurement. When the current signal is below the midpoint, use the low range; when the current signal is above the midpoint, use the high range. Repeat these two steps until the test meets the requirements and converges to the result.

[0070] The specific process is as follows:

[0071] Step 1: Initial scoping

[0072] Set the range search interval (current range [I_min, I_max]) according to the default value.

[0073] The range switching module 6 initially uses a preset default range [I_min, I_max] to test the current signal.

[0074] Step 2: Binary Iteration

[0075] The midpoint value range I_mid of the default interval is used for measurement, that is, I_mid = (I_min + I_max) / 2.

[0076] Then detect the output current signal measurement value,

[0077] (1) When the current signal measurement value is lower than the lower limit of the range, the range is reduced to [I_min, I_mid]

[0078] That is, if the current is lower than the lower limit of the range (e.g., I < 10% FS), the range is reduced to [I_min, I_mid]. FS stands for Full Scale, which is the maximum measurement range.

[0079] (2) When the current signal measurement value is close to saturation, reduce the range to [I_mid, I_max]

[0080] That is, if the current signal measurement value I is higher than 90% FS, the range is narrowed to [I_mid, I_max].

[0081] (3) When the current signal measurement value is in the ideal linear region, stop the iteration.

[0082] That is, if the current is in the ideal linear region (eg, 10% FS≤I≤90% FS), the iteration is stopped.

[0083] Step 3: Convergence determination

[0084] The process terminates when the measured value and the range satisfy the following relationship: the ratio of the measured value to the upper limit of the range is less than or equal to 2 or the maximum number of iterations is reached.

[0085] Specifically, when the following convergence conditions are met, the output current signal measurement value is used as the current test signal:

[0086] (1) The ratio of the current signal measurement value to the upper limit of the range is less than or equal to 2 (I_max / I≤2); or

[0087] (2) The maximum number of iterations is reached.

[0088] The maximum number of iterations is, for example, 5 times.

[0089] Amplification module 5 amplifies the current test signal. Analog-to-digital conversion module 4 (ADC) collects data from the measurement channels, converts the amplified current test signal into a digital current signal, and sends it to FPGA processor 3. FPGA processor 3 calculates the resistance value of the resistor under test on the corresponding measurement channel based on the digital current signal.

[0090] In the embodiment of the present invention, the amplification module 5 adopts a low-noise preamplifier, and the analog-to-digital conversion ADC module 4 adopts a 24-bit ADC chip that supports dynamic baseline calibration.

[0091] In summary, the host computer 1 is responsible for controlling the entire system, such as sending test instructions to the ARM processor 2. The ARM processor 2 converts the test instructions into instructions in a format that can be processed by the FPGA and transmits them to the FPGA processor 3. The FPGA processor 3 makes corresponding selections for the range switch and channel switching. When performing a calibration action, the host computer 1 sends a calibration instruction to the ARM processor 2, which converts it into an instruction F for the FPGA processor 3. The PGA processor 3 operates the calibration resistor matrix 8 to perform automatic calibration. The precision voltage source 9 provides a positive power supply for resistance testing. The ADC module 4 collects the current and amplifies the current flowing through the resistor so that the ADC module 4 can correctly collect the current. The range switching module 6 can operate according to the adaptive range switching algorithm and select the appropriate range for measurement. The channel switching can select the channel to be measured; when the resistance to be measured is less than the minimum value of the measurement, the protection resistor limits the current flowing through the measurement channel to protect the entire system.

[0092] The following describes embodiments of measuring a single channel and multiple channels respectively.

[0093] Example 1: Single channel test process

[0094] 1. The user connects the resistor to be measured to measurement channel 1;

[0095] 2. The instrument is initialized to auto-range mode;

[0096] 3. Use the bisection approximation method to find the appropriate range;

[0097] 4. The ADC samples the current value, and the FPGA processor 3 calculates the resistance value of the resistor to be measured.

[0098] Example 2: Multi-channel batch testing process.

[0099] 1. After measuring channel 1, the resistance calculation result of channel 1 is given;

[0100] 2. Channels 2-N are tested in sequence through the channel switching module 7, and the calculation results of the resistance to be measured on the corresponding measurement channel are given.

[0101] Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the embodiments of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention. Any changes or replacements that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be covered by the scope of protection of the present invention.

Claims

1. A wide range multi-channel high resistance tester, characterized in that: include: Host computer, ARM processor, FPGA processor, analog-to-digital conversion ADC module, amplifier circuit, range switching module, current sampling module, channel switching module, multiple measurement channels and protection resistor module, among which, Each measurement channel is connected to a resistor to be measured, and the protection resistor module includes multiple protection resistors, each protection resistor is connected to a corresponding measurement channel; The host computer is used to perform measurement control and data processing on the wide-range multi-channel high-resistance tester; the host computer sends a test instruction to the ARM processor; The ARM processor is used to convert the test instruction into a format instruction suitable for the FPGA processor, and send the converted test instruction to the FPGA processor; The FPGA processor controls the wide-range switching module and the channel switching module according to the test instruction to control the measurement channel; The channel switching module is used to switch the measurement channel required for measurement under the control of the FPGA processor; The current sampling module includes a plurality of current sampling units, each current sampling unit is used to collect the current signal of the resistance to be measured passing through the corresponding measurement channel; The range switching module is used to select an optimal range according to the real-time current signal using an adaptive range switching algorithm, and output a current test signal according to the optimal range; The amplifier circuit is used to amplify the current test signal; The analog-to-digital conversion (ADC) module is used to convert the amplified current test signal into a current digital signal and send it to the FPGA processor; the FPGA processor calculates the resistance value of the resistor to be measured on the corresponding measurement channel based on the current digital signal.

2. A wide range multi-channel high resistance tester according to claim 1, characterized in that: When the resistance of the resistor to be measured is less than the minimum value of the measurement, the protection resistor limits the current flowing through the corresponding measurement channel to protect the entire system.

3. A wide range multi-channel high resistance tester according to claim 1, characterized in that: The channel switching module switches in sequence under the control of the FPGA processor to test each measurement channel in sequence.

4. A wide range multi-channel high resistance tester according to claim 1, characterized in that: The amplifying circuit adopts a low-noise preamplifier, and the analog-to-digital conversion ADC module adopts a 24-bit ADC chip supporting dynamic baseline calibration.

5. A wide range multi-channel high resistance tester according to claim 1, characterized in that: The range switching module adopts a binary approximation method to select a range for testing.

6. A wide range multi-channel high resistance tester according to claim 5, characterized in that: The range switching module initially uses the preset default interval range [I_min, I_max] to test the current signal, and then takes the midpoint value range I_mid of the default interval for measurement; Detect the output current signal measurement value. When the current signal measurement value is lower than the lower limit of the range, reduce the range to [I_min, I_mid]. When the current signal measurement value is higher than 90% FS, reduce the range to [I_mid, I_max]. When the current signal measurement value is in the ideal linear region, stop the iteration. When the following convergence conditions are met, the output current signal measurement value is used as the current test signal: The ratio of the current signal measurement value to the upper limit of the range is less than or equal to 2; or the maximum number of iterations is reached; FS is the maximum measuring range.

7. A wide range multi-channel high resistance tester according to claim 1, characterized in that: The channel switching module adopts a multi-channel analog switch to switch the corresponding measurement channels under the multi-channel timing control of the FPGA processor.

8. The wide-range multi-channel high-resistance tester according to claim 1, characterized in that: Also includes: A calibration resistor matrix is connected to the FPGA processor and each measurement channel, and is used to perform automatic calibration on each measurement channel under the control of the FPGA processor.

9. A wide range multi-channel high resistance tester according to claim 8, characterized in that: The calibration resistor matrix includes multiple standard resistors and a resistor matrix switching unit. Each standard resistor is connected to a measurement channel respectively. The resistor matrix switching unit is used to calibrate the corresponding measurement channel through the standard resistor under the control of the FPGA processor.

10. The wide-range multi-channel high-resistance tester according to claim 1, characterized in that: Also includes: Precision voltage source, used to provide positive power supply during resistance testing.

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