Impedance detection method, apparatus and device

Abstract

The application discloses an impedance detection method, device and equipment, and the impedance detection method comprises the following steps: controlling a PWM adjustable module to output a square wave signal, so that there is an electric signal in a measured circuit; acquiring a first voltage waveform between a first port and a second port of the measured circuit through a detection circuit; and determining a first impedance type and a first resistance value of the measured circuit according to the square wave signal and the first voltage waveform. By using the technical scheme, the impedance type of the measured circuit can be determined, and the resistance value of the measured circuit can be calculated, so that the operation is simple, the detection is fast, the automatic detection can be realized, and the detection efficiency is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of circuit testing technology, and in particular to an impedance testing method, apparatus, and equipment. Background Technology

[0002] In existing technologies, impedance testing generally uses multimeters. However, the use of multimeters is usually based on experience for adjustment. When encountering situations with large inductive or capacitive impedances, it is impossible to provide specific impedance types and resistance values. Summary of the Invention

[0003] The present invention provides an impedance detection method, apparatus, and device to solve the above-mentioned problems.

[0004] According to one aspect of the present invention, an impedance detection method is provided, which detects the impedance type and resistance value of a circuit under test based on a PWM adjustable module and a detection circuit; the PWM adjustable module is electrically connected to the detection circuit, and the detection circuit is electrically connected to the circuit under test; the circuit under test includes a first port and a second port; The impedance detection method includes: The PWM adjustable module is controlled to output a square wave signal so that there is an electrical signal in the circuit under test. The detection circuit obtains a first voltage waveform between the first port and the second port of the circuit under test. Based on the square wave signal and the first voltage waveform, the first impedance type and the first resistance value of the circuit under test are determined.

[0005] Optionally, the first voltage waveform includes a first changing phase and a stable phase; the first changing phase includes a first moment and a second moment, wherein the voltage value of the first voltage waveform at the first moment is less than the voltage value of the first voltage waveform at the second moment; the stable phase includes a third moment and a fourth moment, wherein the voltage value of the first voltage waveform at the third moment is equal to the voltage value of the first voltage waveform at the fourth moment. Determining the first impedance type and first resistance value of the circuit under test based on the square wave signal and the first voltage waveform includes: Obtain the first slope of the first voltage waveform at the first time and the second slope of the first voltage waveform at the second time; Based on the relationship between the first slope and the second slope, the first impedance type of the circuit under test is determined; Obtain the third voltage value of the first voltage waveform at the third time and / or the fourth voltage value of the first voltage waveform at the fourth time; The first resistance value of the circuit under test is determined based on the square wave signal and the voltage value at the high level, as well as the third voltage value and / or the fourth voltage value.

[0006] Optionally, before acquiring the third voltage value of the first voltage waveform at the third time and / or the fourth voltage value of the first voltage waveform at the fourth time, the method further includes: Determine whether the first voltage waveform has a stable phase; If not, the duty cycle of the square wave signal is increased by the first preset increment.

[0007] Optionally, the first voltage waveform further includes a second change phase; the second change phase includes a fifth moment and a sixth moment, wherein the voltage value of the first voltage waveform at the fifth moment is greater than the voltage value of the first voltage waveform at the second moment; Determining the first impedance type and first resistance value of the circuit under test based on the square wave signal and the first voltage waveform further includes: Obtain the fifth slope of the first voltage waveform at the fifth time and the sixth slope of the first voltage waveform at the sixth time; The first impedance type of the circuit under test is verified based on the relationship between the fifth slope and the sixth slope.

[0008] Optionally, controlling the PWM adjustable module to output a square wave signal to ensure an electrical signal within the circuit under test includes: The PWM adjustable module is controlled to output the square wave signal at a preset time interval to perform M measurements on the circuit under test within a unit time; wherein the unit time is M times the preset time, and M is an integer greater than 2. Determining the first impedance type and first resistance value of the circuit under test based on the square wave signal and the first voltage waveform includes: Based on the first voltage waveform, determine the impedance type of the circuit under test M times and the initial resistance value of the circuit under test M times within a preset time. The number of times the circuit under test is classified as the first type is greater than M / 2. If so, then the first judgment type is determined to be the first impedance type of the circuit under test; Calculate the average of the initial resistance values ​​of the M circuits under test, and record it as the first average value; The first average value is determined as the first resistance value of the circuit under test.

[0009] Optionally, the impedance detection method further includes: The PWM adjustable module is controlled to output a sine wave signal of a first preset frequency, a sine wave signal of a second preset frequency, ..., a sine wave signal of an Nth preset frequency, respectively, so as to perform N measurements on the circuit under test, where N is an integer greater than 2; The detection circuit acquires the first second voltage waveform, the second second voltage waveform, ..., the Nth second voltage waveform between the first port and the second port of the circuit under test, corresponding to the first preset frequency sine wave signal, the second preset frequency sine wave signal, ..., the Nth preset frequency sine wave signal; Based on the N sinusoidal signals and N second voltage waveforms that correspond one-to-one, the second impedance type and second resistance value of the circuit under test are determined; Verify the first impedance type and the first resistance value based on the second impedance type and the second resistance value.

[0010] Optionally, before acquiring the first voltage waveform between the first port and the second port of the circuit under test through the detection circuit, the method further includes: The detection circuit acquires the first voltage waveform between the first port of the circuit under test and ground, and the second voltage waveform between the second port of the circuit under test and ground. Based on the square wave signal, the first voltage waveform to ground, and the second voltage waveform to ground, determine whether the first port and the second port of the circuit under test are both open to ground; If so, the detection circuit obtains the first voltage waveform between the first port and the second port of the circuit under test.

[0011] According to another aspect of the present invention, an impedance detection device is provided, which detects the impedance type and resistance value of a circuit under test based on a PWM adjustable module and a detection circuit; the PWM adjustable module is electrically connected to the detection circuit, and the detection circuit is electrically connected to the circuit under test; the circuit under test includes a first port and a second port. The impedance detection device includes: The signal control module is used to control the PWM adjustable module to output a square wave signal so that there is an electrical signal in the circuit under test. The waveform recording module is used to acquire the first voltage waveform between the first port and the second port of the circuit under test through the detection circuit; The calculation module is used to determine the first impedance type and the first resistance value of the circuit under test based on the square wave signal and the first voltage waveform.

[0012] According to another aspect of the present invention, an impedance detection device is provided, comprising: a power supply module, a PWM adjustable module, a detection circuit, and a controller; the controller includes the aforementioned impedance detection device. The power supply module is electrically connected to the PWM adjustable module, the detection circuit, and the controller, respectively; the PWM adjustable module is electrically connected to the detection circuit; the detection circuit is electrically connected to the circuit under test; and the controller is communicatively connected to the PWM adjustable module and the detection circuit, respectively. The power supply module is used to supply power to the PWM adjustable module, the detection circuit, and the controller; the PWM adjustable module is used to input a PWM signal to the circuit under test through the detection circuit; the PWM signal includes a square wave signal; the detection circuit is used to acquire the voltage signal of the PWM adjustable module and the voltage signal of the circuit under test; the controller is used to control the PWM adjustable module and acquire the voltage waveform of the PWM signal and the voltage waveform of the circuit under test.

[0013] Optionally, it also includes: a protection module: The detection circuit is electrically connected to the circuit under test through the protection module.

[0014] The technical solution of this invention obtains the voltage waveform of the circuit under test by inputting a square wave signal to the circuit under test and simultaneously acquiring the voltage signal of the circuit under test. Based on the impedance characteristics, the impedance type of the circuit under test can be determined and the resistance value of the circuit under test can be calculated. The operation is simple, the detection is fast, and automated detection can be achieved, effectively improving the detection efficiency.

[0015] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of an impedance detection device provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of another impedance detection device provided in Embodiment 1 of the present invention; Figure 3 This is a flowchart of an impedance detection method provided in Embodiment 2 of the present invention; Figure 4 This is a flowchart of an impedance detection method provided in Embodiment 3 of the present invention; Figure 5 This is a flowchart of an impedance detection method provided in Embodiment 4 of the present invention; Figure 6 This is a schematic diagram of an impedance detection device provided in Embodiment 5 of the present invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0020] Example 1 Figure 1 This is a schematic diagram of an impedance detection device provided in Embodiment 1 of the present invention. (Reference) Figure 1 The impedance detection device includes a power supply module 10, a PWM adjustable module 20, a detection circuit 30, and a controller 40. The power supply module 10 is electrically connected to the PWM adjustable module 20, the detection circuit 30, and the controller 40. The PWM adjustable module 20 is electrically connected to the detection circuit 30; the detection circuit 30 is electrically connected to the circuit under test; and the controller 40 is communicatively connected to both the PWM adjustable module 20 and the detection circuit 30. The power supply module 10 supplies power to the PWM adjustable module, the detection circuit, and the controller. The PWM adjustable module inputs a PWM signal to the circuit under test through the detection circuit. The PWM signal includes a square wave signal. The detection circuit acquires the voltage signal from the PWM adjustable module and the voltage signal from the circuit under test. The controller controls the PWM adjustable module and acquires the voltage waveform of the PWM signal and the voltage waveform of the circuit under test.

[0021] The power supply module 10 can be a dual-channel power supply with stable output voltage regulation, which can ensure the power requirements of the impedance detection equipment itself, and also ensure sufficient output power for measuring the impedance type and resistance value of the circuit under test. The PWM adjustable module 20 includes a PWM signal generation unit 21 and a power amplifier 22. The PWM signal generation unit 21 can generate adaptive constant voltage square waves and frequency-adjustable sine waves, etc. The PWM signals are amplified by the power amplifier 22 and used to detect the impedance type and resistance value in the circuit under test. The detection circuit 30 includes an input protection circuit 31, a programmable amplifier circuit 32, and a high-speed analog-to-digital converter (ADC) 33. It can receive the PWM signal from the adjustable PWM module 20, acquire the PWM signal and the voltage signal of the circuit under test, and convert them into digital signals. The high-speed ADC can be an AD76556 with a sampling accuracy of at least 16 bits and a conversion speed of at least 100kHz. The controller 40 includes, but is not limited to, a microcontroller unit (MCU) and a central processing unit (CPU). For example, the controller 40 can be a 32-bit ARM core CPU with a main frequency of at least 32MHz, containing an internal floating-point arithmetic unit. It controls the PWM signal of the adjustable PWM module 20 and receives the digital signal output from the detection circuit 30 via a high-speed SPI interface to acquire the voltage waveform and calculate the impedance value to determine the impedance type and resistance value of the circuit under test.

[0022] For example, the impedance detection device includes a first detection line Test1 and a second detection line Test2, which can be electrically connected to the first port 01 and the second port 02 of the circuit under test, respectively. The PWM signal generation unit 21 can output a square wave with a pulse frequency range from 0.1Hz to 50kHz through an SG5638 signal generator and a Schmitt trigger, and its frequency and duty cycle can be adjusted by the controller 40 via SPI input commands. The controller 40 can calculate the corresponding impedance value based on different PWM effective values ​​and frequency changes, thereby identifying the impedance type and resistance value of the circuit under test.

[0023] In an optional embodiment, the input protection circuit 31 includes an adjustable resistor Rs, and the detection circuit 30 includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. The first resistor R1 and the second resistor R2 form a first DC bridge, and the third resistor R3 and the fourth resistor R4 form a second DC bridge. The first DC bridge, the second DC bridge, and the adjustable resistor Rs can form a dual voltage difference test loop for measuring impedance. The adjustable resistor Rs is used for resistance compensation and needs to be calibrated at the factory.

[0024] Optional, continue to refer to Figure 1 The impedance detection device also includes a protection module 50, and the detection circuit 30 is electrically connected to the circuit under test through the protection module 50.

[0025] For example, the protection module 50 includes an overvoltage protection tube 51 and a resettable fuse 52. The overvoltage protection tube 51 can protect the impedance detection equipment when the high voltage of the circuit under test is discharged, and can also protect personnel from short-term lightning strikes. Under the action of the overvoltage protection tube 51, the resettable fuse 52 is used to cut off the high voltage and enter a high-resistance state, thereby protecting the impedance detection equipment, and can recover its state within a certain period of time. In this way, the impedance detection equipment can always operate within a safe voltage range, improving the lifespan of the impedance detection equipment.

[0026] In an optional embodiment, the impedance detection device further includes a display (not shown) connected to the controller, which can display the impedance type and resistance value of the circuit under test.

[0027] In an alternative embodiment, all the circuitry in the impedance sensing device can be integrated together, such as... Figure 2 As shown, this can improve the integration of impedance detection equipment, reduce its size, and make it easier for staff to carry.

[0028] In Embodiment 1 of this invention, by setting a power supply module, a PWM adjustable module, a detection circuit, and a controller in the impedance detection device, an adjustable square wave signal with a duty cycle can be provided to the circuit under test. At the same time, the voltage signal of the circuit under test is acquired, and the voltage waveform of the circuit under test is obtained. Based on the impedance characteristics, the impedance type of the circuit under test can be determined, and the resistance value of the circuit under test can be calculated. The operation is simple, the detection is fast, and automated detection can be achieved, effectively improving the detection efficiency.

[0029] Example 2 Figure 3 This is a flowchart of an impedance detection method provided in Embodiment 2 of the present invention. This embodiment is applicable to impedance detection during the completion and acceptance of power grid distribution lines. The method can be executed by an impedance detection device, which can be implemented in hardware and / or software. The impedance detection device can be configured in the controller of the impedance detection equipment. Figure 3 As shown, the method includes: S110 controls the PWM adjustable module to output a square wave signal so that there is an electrical signal in the circuit under test.

[0030] For example, refer to Figure 1 The first DC bridge and the second DC bridge in the detection circuit 30 of the impedance detection device can form a bridge voltage measurement circuit. When the first port 01 and the second port 02 of the circuit under test are connected to the impedance detection device through the first detection line Test1 and the second detection line Test2, the PWM adjustable module 20 can inject a square wave signal into the circuit under test through the input protection circuit 31. At the same time, two voltage signals will be generated at nodes N3 and N4 at the input end of the programmable amplifier circuit 32. Based on the voltage signals of nodes N3 and N4, as well as the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4, the voltage V1 of the first node N1 and the voltage V2 of the second node N2 can be determined. Combining the adjustable resistor Rs and the Kirchhoff voltage balance principle, the impedance value of the circuit under test can be roughly obtained.

[0031] S120. The first voltage waveform between the first port and the second port of the circuit under test is obtained through the detection circuit.

[0032] Specifically, the detection circuit can acquire two voltage signals generated by nodes N3 and N4 at a higher frequency and with higher precision. By calculation, the voltage V1 of the first node N1 and the voltage V2 of the second node N2 can be obtained. In other words, the voltage value between the first port O1 and the second port O2 of the circuit under test can be obtained in real time, which is the first voltage waveform.

[0033] S130. Based on the square wave signal and the first voltage waveform, determine the first impedance type and the first resistance value of the circuit under test.

[0034] The first impedance type is the impedance type of the circuit under test determined by the method of S110-S130, and the first resistance value is the resistance value of the circuit under test calculated by the method of S110-S130.

[0035] For example, when the square wave signal changes from low level to high level, if the impedance of the circuit under test is small first and then large, the first impedance type of the circuit under test is capacitive; if the impedance of the circuit under test is large first and then small, the first impedance type of the circuit under test is inductive; if the impedance of the circuit under test is relatively stable, the first impedance type of the circuit under test is resistive.

[0036] When the two voltage signals generated at nodes N3 and N4 are stable, that is, when the voltage V1 at the first node N1 and the voltage V2 at the second node N2 are stable, based on Kirchhoff's current balance principle, Where Rp is the resistor of the resettable fuse 52 in the protection module 50, and R is the resistance of the circuit under test. That is, the first resistance value.

[0037] Optionally, the first voltage waveform includes a first changing phase and a stable phase; the first changing phase includes a first moment and a second moment, where the voltage value of the first voltage waveform at the first moment is less than the voltage value of the first voltage waveform at the second moment; the stable phase includes a third moment and a fourth moment, where the voltage value of the first voltage waveform at the third moment is equal to the voltage value of the first voltage waveform at the fourth moment. Determining the first impedance type and the first resistance value of the circuit under test based on the square wave signal and the first voltage waveform includes: acquiring the first slope of the first voltage waveform at the first moment and the second slope of the first voltage waveform at the second moment; determining the first impedance type of the circuit under test based on the relationship between the magnitudes of the first slope and the second slope; acquiring the third voltage value of the first voltage waveform at the third moment and / or the fourth voltage value of the first voltage waveform at the fourth moment; and determining the first resistance value of the circuit under test based on the square wave signal, the voltage value at a high level, and the third and / or fourth voltage values.

[0038] Specifically, the first stage of the first voltage waveform change is when the square wave signal changes from low to high level. During this stage, the voltage between the first and second ports of the circuit under test gradually increases. When the first slope is greater than the second slope, the voltage across the circuit under test changes rapidly at first and then slows down, indicating that the impedance of the circuit under test increases from small to large. Therefore, the first impedance type of the circuit under test can be determined to be capacitive. When the first slope is less than the second slope, the voltage across the circuit under test changes slowly at first and then accelerates, indicating that the impedance of the circuit under test decreases from large to small. Therefore, the first impedance type of the circuit under test can be determined to be inductive. When the first slope equals the second slope, the voltage change rate across the circuit under test is stable, indicating that the impedance of the circuit under test is stable. Therefore, the first impedance type of the circuit under test can be determined to be resistive. The stable phase of the first voltage waveform is the high-level phase of the square wave signal. At this time, there are electrical signals in both the detection circuit and the circuit under test, and the voltage V1 of the first node N1 and the voltage V2 of the second node N2 are not zero. The resistance value of the circuit under test can be calculated according to Kirchhoff's current balance principle, which is the first resistance value.

[0039] Optionally, the first voltage waveform further includes a second change phase; the second change phase includes a fifth time point and a sixth time point, wherein the voltage value of the first voltage waveform at the fifth time point is greater than the voltage value of the first voltage waveform at the second time point. Determining the first impedance type and first resistance value of the circuit under test based on the square wave signal and the first voltage waveform further includes: acquiring the fifth slope of the first voltage waveform at the fifth time point and the sixth slope of the first voltage waveform at the sixth time point; and verifying the first impedance type of the circuit under test based on the relationship between the magnitudes of the fifth and sixth slopes.

[0040] Specifically, the second stage of the first voltage waveform is the transition from a high level to a low level for the square wave signal. During this stage, the voltage between the first and second ports of the circuit under test gradually decreases. When the fifth slope is less than the sixth slope (i.e., the absolute value of the fifth slope is greater than the absolute value of the sixth slope), the voltage across the circuit under test initially changes rapidly, then slows down, indicating that the impedance of the circuit under test increases from small to large. Therefore, the first impedance type of the circuit under test can be determined to be capacitive. When the fifth slope is greater than the second slope (i.e., the absolute value of the fifth slope is less than the absolute value of the sixth slope), the voltage across the circuit under test initially changes slowly, then speeds up, indicating that the impedance of the circuit under test decreases from large to small. Therefore, the first impedance type of the circuit under test can be determined to be inductive. When the fifth slope equals the sixth slope, the voltage change rate across the circuit under test is stable, indicating that the impedance of the circuit under test is stable. Therefore, the first impedance type of the circuit under test can be determined to be resistive. This allows for confirmation and judgment of the impedance type of the circuit under test, improving the accuracy of the judgment results.

[0041] Optionally, before obtaining the third voltage value of the first voltage waveform at the third time and / or the fourth voltage value of the first voltage waveform at the fourth time, the method further includes: determining whether the first voltage waveform has a stable phase; if not, increasing the duty cycle of the square wave signal by a first preset increment.

[0042] For example, if the inductance or capacitance in the circuit under test is large, making it impossible for the voltage across the circuit under test to reach a stable state during the high-level time of the square wave signal, the high-level time of the square wave signal can be increased, i.e., the duty cycle of the square wave signal can be increased by a preset increment, so that the voltage across the circuit under test can reach a stable state during the high-level time of the square wave signal, thereby determining the first resistance value.

[0043] In the second embodiment of the present invention, a square wave signal is input to the circuit under test, and the voltage signal of the circuit under test is collected at the same time to obtain the voltage waveform of the circuit under test. Based on the impedance characteristics, the impedance type of the circuit under test can be determined and the resistance value of the circuit under test can be calculated. The operation is simple, the detection is fast, and automated detection can be realized, effectively improving the detection efficiency.

[0044] Optionally, controlling the PWM adjustable module to output a square wave signal to ensure an electrical signal in the circuit under test includes: controlling the PWM adjustable module to output a square wave signal at a preset time interval to perform M measurements on the circuit under test within a unit time; wherein the unit time is M times the preset time, and M is an integer greater than 2. Based on the square wave signal and the first voltage waveform, determining the first impedance type and the first resistance value of the circuit under test includes: determining the impedance type of the circuit under test M times and the initial resistance values ​​of M circuits under test within a preset time based on the first voltage waveform; determining whether the number of times the circuit under test falls into the first determination type is greater than M / 2; if so, determining the first determination type as the first impedance type of the circuit under test; calculating the average value of the initial resistance values ​​of the M circuits under test and recording it as the first average value; and determining the first average value as the first resistance value of the circuit under test.

[0045] The unit time can be 1 second, 1 minute, 2 seconds, 5 seconds, etc., and this embodiment of the invention does not limit this. The preset time interval can be set according to actual needs, and this embodiment of the invention does not limit this either. The first judgment type is the result of judging the impedance type of the circuit under test in a single instance based on a square wave signal, which can be resistive, inductive, or capacitive. The initial resistance value is the result of calculating the resistance value of the circuit under test in a single instance based on a square wave signal.

[0046] For example, a square wave signal is output once every preset time interval within a unit of time. The square wave signal includes both high-level and low-level signals. Simultaneously, while outputting the square wave signal at intervals, the voltage across the circuit under test is acquired in real time, resulting in the first voltage waveform at the measured end of the circuit under test. Each time a square wave signal is output, the impedance type of the circuit under test can be determined and the resistance value can be calculated. Multiple first judgment types and multiple initial resistance values ​​can be obtained within a unit of time. If more than a certain number of first judgment types are of the same impedance type, it indicates that the determined impedance type is relatively accurate, and the impedance type of the circuit under test can be confirmed as the first judgment type. Averaging the resistance values ​​of the circuit under test obtained from multiple calculations as the first resistance value of the circuit under test can improve the accuracy of the results.

[0047] Example 3 Figure 4 This is a flowchart of an impedance detection method provided in Embodiment 3 of the present invention. While the methods in the above embodiments perform impedance detection on the circuit under test using direct current, Embodiment 3 of the present invention adds the step of verifying the impedance detection results of the circuit under test using alternating current. Figure 4 As shown, the method includes: S210 controls the PWM adjustable module to output a square wave signal so that there is an electrical signal in the circuit under test.

[0048] S220. The first voltage waveform between the first port and the second port of the circuit under test is obtained through the detection circuit.

[0049] S230. Based on the square wave signal and the first voltage waveform, determine the first impedance type and the first resistance value of the circuit under test.

[0050] S240 controls the PWM adjustable module to output sine wave signals of the first preset frequency, the second preset frequency, ..., the Nth preset frequency, respectively, so as to perform N measurements on the circuit under test, where N is an integer greater than 2.

[0051] S250. Through the detection circuit, acquire the first second voltage waveform, the second second voltage waveform, ..., the Nth second voltage waveform between the first port and the second port of the circuit under test corresponding to the first preset frequency sine wave signal, the second preset frequency sine wave signal, ..., the Nth preset frequency sine wave signal.

[0052] S260. Based on the N sinusoidal wave signals and N second voltage waveforms that correspond one-to-one, determine the second impedance type and the second resistance value of the circuit under test.

[0053] S270. Verify the first impedance type and the first resistance value based on the second impedance type and the second resistance value.

[0054] The second impedance type is the impedance type of the circuit under test determined by the method of S240-S260, and the second resistance value is the resistance value of the circuit under test calculated by the method of S240-S260.

[0055] For example, the controller can control the PWM adjustable module to generate sinusoidal signals of different frequencies within the range of 0.05 to 100 Hz. If the impedance of the measured resistor increases with the increase of the sinusoidal signal frequency, it indicates that the impedance type of the measured circuit is inductive; if the impedance of the measured resistor decreases with the increase of the sinusoidal signal frequency, it indicates that the impedance type of the measured circuit is capacitive; if the impedance of the measured resistor does not change with the increase of the sinusoidal signal frequency, it indicates that the impedance type of the measured circuit is resistive. Using the LC oscillation frequency formula, when the controller controls the PWM adjustable module 20 to generate frequency and duty cycle adjustments, the frequency value can be obtained by synchronizing the recorded duty cycle value with the voltage change of the oscillation circuit. This allows for the calculation of a more accurate impedance value. Generally, the second impedance type and second resistance value of the circuit under test determined using methods S240-S260 should be the same as or similar to the first impedance type and first resistance value of the circuit under test determined using methods S210-S230.

[0056] In an optional embodiment, if the impedance type of the circuit under test is resistive or inductive, the first impedance type and first resistance value of the circuit under test determined by the method of S210-S230 can be output; if the impedance type of the circuit under test is capacitive, the first impedance type and first resistance value of the circuit under test determined by the method of S210-S230 can be output.

[0057] If the specific impedance value cannot be calculated using methods S240-S260, it indicates that capacitive reactance compensation exists in the circuit under test and has not been completely eliminated. In this case, the circuit needs to be checked to ensure that the capacitor compensation or reactor is completely isolated to completely eliminate the capacitive reactance compensation and avoid high-voltage live measurement, thus protecting the impedance testing equipment and personnel. If the specific resistance value cannot be calculated using methods S210-S230 and S240-S260, or if the resistance value is infinite, it indicates that there is a switch or unrelated terminal in the middle. In this case, it is necessary to confirm whether the power is disconnected and whether the connection is incorrect.

[0058] In the third embodiment of the present invention, the impedance of the circuit under test is detected by AC to obtain the second impedance type and the second resistance value of the circuit under test, so as to verify the first impedance type and the first resistance value of the circuit under test. In this way, the accuracy of the detection results can be improved.

[0059] Example 4 Figure 5 This is a flowchart of an impedance detection method provided in Embodiment 4 of the present invention. This embodiment, compared to the previous embodiments, adds the detection of the ground impedance properties of the first and second ports of the circuit under test, respectively. Figure 5 As shown, the method includes: S310 controls the PWM adjustable module to output a square wave signal so that there is an electrical signal in the circuit under test.

[0060] S320. The detection circuit acquires the first voltage waveform between the first port of the circuit under test and ground, and the second voltage waveform between the second port of the circuit under test and ground.

[0061] S330. Based on the square wave signal, the first voltage waveform to ground, and the second voltage waveform to ground, determine whether both the first and second ports of the circuit under test are open to ground. If so, execute S340.

[0062] S340 controls the PWM adjustable module to output a square wave signal so that there is an electrical signal in the circuit under test.

[0063] S350: The detection circuit acquires the first voltage waveform between the first port and the second port of the circuit under test. S360. Based on the square wave signal and the first voltage waveform, determine the first impedance type and the first resistance value of the circuit under test.

[0064] For example, the control PWM adjustable module inputs a square wave signal to the first port of the circuit under test (DUT) to obtain the first voltage waveform between the first port and ground. Based on the square wave signal, the first voltage waveform, and the second voltage waveform, the impedance type and resistance value between the first port and ground can be determined. If the resistance value between the first port and ground can be calculated, and the impedance type can be determined, it indicates a connection between the first port and ground, which is detrimental to impedance detection. The connecting line between the first port and ground needs to be disconnected to make the first port open-circuit to ground. If the resistance between the first port and ground is infinite, it indicates no connection between the first port and ground, and the first port is open-circuit to ground. Similarly, it can be determined whether there is a connection between the second port and ground. If there is a connection, the connecting line between the second port and ground is disconnected to make the second port open-circuit to ground.

[0065] In the fourth embodiment of the present invention, before performing impedance testing on the circuit under test, the first port and the second port of the circuit under test are tested to ground respectively, and the impedance testing of the circuit under test is performed when both the first port and the second port are open to ground. In this way, the reliability of the test results can be improved.

[0066] Example 5 Figure 6 This is a schematic diagram of an impedance detection device provided in Embodiment 5 of the present invention. Figure 6 As shown, the device includes: The signal control module 610 is used to control the output of the square wave signal of the PWM adjustable module so that there is an electrical signal in the circuit under test. The waveform recording module 620 is used to acquire the first voltage waveform between the first port and the second port of the circuit under test through the detection circuit; The arithmetic module 630 is used to determine the first impedance type and the first resistance value of the circuit under test based on the square wave signal and the first voltage waveform.

[0067] The impedance detection device provided in the embodiments of the present invention can execute the impedance detection method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the method.

[0068] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0069] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An impedance detection method, characterized in that, The impedance type and resistance value of the circuit under test are detected based on a PWM adjustable module and a detection circuit; the PWM adjustable module is electrically connected to the detection circuit, and the detection circuit is electrically connected to the circuit under test. The circuit under test includes a first port and a second port; The impedance detection method includes: The PWM adjustable module is controlled to output a square wave signal so that there is an electrical signal in the circuit under test. The detection circuit obtains a first voltage waveform between the first port and the second port of the circuit under test. Based on the square wave signal and the first voltage waveform, determine the first impedance type and the first resistance value of the circuit under test; The first voltage waveform includes a first change phase and a stable phase; the first change phase includes a first moment and a second moment, wherein the voltage value of the first voltage waveform at the first moment is less than the voltage value of the first voltage waveform at the second moment; the stable phase includes a third moment and a fourth moment, wherein the voltage value of the first voltage waveform at the third moment is equal to the voltage value of the first voltage waveform at the fourth moment. Determining the first impedance type and first resistance value of the circuit under test based on the square wave signal and the first voltage waveform includes: Obtain the first slope of the first voltage waveform at the first time and the second slope of the first voltage waveform at the second time; Based on the relationship between the first slope and the second slope, the first impedance type of the circuit under test is determined; Obtain the third voltage value of the first voltage waveform at the third time and / or the fourth voltage value of the first voltage waveform at the fourth time; The first resistance value of the circuit under test is determined based on the square wave signal and the voltage value at the high level, as well as the third voltage value and / or the fourth voltage value.

2. The impedance detection method according to claim 1, characterized in that, Before acquiring the third voltage value of the first voltage waveform at the third time and / or the fourth voltage value of the first voltage waveform at the fourth time, the method further includes: Determine whether the first voltage waveform has a stable phase; If not, the duty cycle of the square wave signal is increased by the first preset increment.

3. The impedance detection method according to claim 1, characterized in that, The first voltage waveform further includes a second change phase; the second change phase includes a fifth moment and a sixth moment, wherein the voltage value of the first voltage waveform at the fifth moment is greater than the voltage value of the first voltage waveform at the sixth moment; Determining the first impedance type and first resistance value of the circuit under test based on the square wave signal and the first voltage waveform further includes: Obtain the fifth slope of the first voltage waveform at the fifth time and the sixth slope of the first voltage waveform at the sixth time; The first impedance type of the circuit under test is verified based on the relationship between the fifth slope and the sixth slope.

4. The impedance detection method according to claim 1, characterized in that, Controlling the PWM adjustable module to output a square wave signal so that there is an electrical signal in the circuit under test includes: The PWM adjustable module is controlled to output the square wave signal at a preset time interval to perform M measurements on the circuit under test within a unit time; wherein the unit time is M times the preset time, and M is an integer greater than 2. Determining the first impedance type and first resistance value of the circuit under test based on the square wave signal and the first voltage waveform includes: Based on the first voltage waveform, determine the impedance type of the circuit under test M times and the initial resistance value of the circuit under test M times within a preset time. The number of times the circuit under test is classified as the first type is greater than M / 2. If so, then the first judgment type is determined to be the first impedance type of the circuit under test; Calculate the average of the initial resistance values ​​of the M circuits under test, and record it as the first average value; The first average value is determined as the first resistance value of the circuit under test.

5. The impedance detection method according to claim 1, characterized in that, The impedance detection method further includes: The PWM adjustable module is controlled to output a sine wave signal of a first preset frequency, a sine wave signal of a second preset frequency, ..., a sine wave signal of an Nth preset frequency, respectively, so as to perform N measurements on the circuit under test, where N is an integer greater than 2; The detection circuit acquires the first second voltage waveform, the second second voltage waveform, ..., the Nth second voltage waveform between the first port and the second port of the circuit under test, corresponding to the first preset frequency sine wave signal, the second preset frequency sine wave signal, ..., the Nth preset frequency sine wave signal; Based on the N sinusoidal signals and N second voltage waveforms that correspond one-to-one, the second impedance type and second resistance value of the circuit under test are determined; Verify the first impedance type and the first resistance value based on the second impedance type and the second resistance value.

6. The impedance detection method according to claim 1, characterized in that, Before acquiring the first voltage waveform between the first port and the second port of the circuit under test through the detection circuit, the method further includes: The PWM adjustable module is controlled to output a square wave signal so that there is an electrical signal in the circuit under test. The detection circuit acquires the first voltage waveform between the first port of the circuit under test and ground, and the second voltage waveform between the second port of the circuit under test and ground. Based on the square wave signal, the first voltage waveform to ground, and the second voltage waveform to ground, determine whether the first port and the second port of the circuit under test are both open to ground; If so, the PWM adjustable module is controlled to output a square wave signal so that there is an electrical signal in the circuit under test; the detection circuit obtains the first voltage waveform between the first port and the second port of the circuit under test; and the first impedance type and first resistance value of the circuit under test are determined according to the square wave signal and the first voltage waveform.

7. An impedance detection device, characterized in that, The impedance type and resistance value of the circuit under test are detected based on a PWM adjustable module and a detection circuit; the PWM adjustable module is electrically connected to the detection circuit, and the detection circuit is electrically connected to the circuit under test. The circuit under test includes a first port and a second port; The impedance detection device includes: The signal control module is used to control the PWM adjustable module to output a square wave signal so that there is an electrical signal in the circuit under test. The waveform recording module is used to acquire the first voltage waveform between the first port and the second port of the circuit under test through the detection circuit; The calculation module is used to determine the first impedance type and the first resistance value of the circuit under test based on the square wave signal and the first voltage waveform. The first voltage waveform includes a first change phase and a stable phase; the first change phase includes a first moment and a second moment, wherein the voltage value of the first voltage waveform at the first moment is less than the voltage value of the first voltage waveform at the second moment; the stable phase includes a third moment and a fourth moment, wherein the voltage value of the first voltage waveform at the third moment is equal to the voltage value of the first voltage waveform at the fourth moment. The computing module is also used for: Obtain the first slope of the first voltage waveform at the first time and the second slope of the first voltage waveform at the second time; Based on the relationship between the first slope and the second slope, the first impedance type of the circuit under test is determined; Obtain the third voltage value of the first voltage waveform at the third time and / or the fourth voltage value of the first voltage waveform at the fourth time; The first resistance value of the circuit under test is determined based on the square wave signal and the voltage value at the high level, as well as the third voltage value and / or the fourth voltage value.

8. An impedance detection device, characterized in that, include: The power supply module, the PWM adjustable module, the detection circuit, and the controller; the controller includes the impedance detection device as described in claim 7. The power supply module is electrically connected to the PWM adjustable module, the detection circuit, and the controller, respectively; the PWM adjustable module is electrically connected to the detection circuit; the detection circuit is electrically connected to the circuit under test; and the controller is communicatively connected to the PWM adjustable module and the detection circuit, respectively. The power supply module is used to supply power to the PWM adjustable module, the detection circuit, and the controller; the PWM adjustable module is used to input a PWM signal to the circuit under test through the detection circuit; the PWM signal includes a square wave signal; the detection circuit is used to acquire the voltage signal of the PWM adjustable module and the voltage signal of the circuit under test; the controller is used to control the PWM adjustable module and acquire the voltage waveform of the PWM signal and the voltage waveform of the circuit under test.

9. The detection device according to claim 8, characterized in that, Also includes: Protection module: The detection circuit is electrically connected to the circuit under test through the protection module.

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