Impedance test device test parameter setting method and impedance test device test method

Abstract

This invention relates to the field of impedance testing equipment technology, and discloses a method for setting test parameters and a method for testing impedance testing equipment. The method includes: adjusting the output impedance of the impedance testing equipment to its maximum and setting the range; applying different test signals to identify the type of the device under test (DUT); when a polarized capacitor is detected in reverse connection, the impedance testing equipment outputs a reverse connection warning and stops the test; determining the measurement range, test frequency, equivalent circuit model, DC bias voltage for testing, and AC signal level for testing; acquiring the impedance amplitude of the DUT; determining the range setting; based on the impedance amplitude, switching the impedance testing equipment to a low output impedance mode or maintaining a high output impedance mode; fine-tuning the AC signal level when the measured signal deviates from the matched dynamic range, and returning to acquire the impedance amplitude of the DUT. This invention can automatically set the test parameters of the impedance testing equipment.

Description

Technical Field

[0001] This invention relates to the field of impedance testing equipment technology, and in particular to a method for setting test parameters for impedance testing equipment and a test method for impedance testing equipment. Background Technology

[0002] Impedance testing equipment (e.g., LCR meters, impedance analyzers) are electronic instruments used to measure the values ​​of inductance, capacitance, and resistance. When testing resistance, capacitance, and inductance, several core test parameters need to be correctly set: test frequency, DC bias voltage, AC signal level, equivalent circuit model (series or parallel), measurement range, and output impedance. The selection of these test parameters depends entirely on the physical properties of the device under test: device type, value range (corresponding capacitance or resistance value), polarity (e.g., non-polarized ceramic capacitors, polarized aluminum electrolytic / tantalum electrolytic capacitors), and connection direction (i.e., whether polarized capacitors have been correctly connected by the user), etc.

[0003] Most existing impedance testing equipment requires the following steps when operated manually: identify the type of device and whether it has polarity (if it is a capacitor) → consult the datasheet or industry standard to determine the test parameters and equivalent circuit model → set each test parameter on the impedance testing equipment panel one by one (note the connection direction of polarized capacitors). Some existing mainstream impedance testing equipment (e.g., Keysight E4980A series, Hioki IM3536 series, Tonghui TH2838 series, etc.) have automatic setting functions, mainly reflected in: (1) Automatic range selection: According to the measured impedance amplitude, it dynamically switches to the optimal range to ensure that the measured signal always falls within a reasonable dynamic range; (2) Automatic AC signal level adjustment: Some models of impedance testing equipment can automatically adjust the AC signal level according to the impedance of the device under test; (3) Automatic output impedance matching: Some models of impedance testing equipment can automatically switch the output impedance according to the range currently used (e.g., high impedance range with high output impedance, low impedance range with low output impedance), which is a hardware-driven follow-up switching; (4) Simple parameter identification: After the user manually sets the test frequency, DC voltage bias and equivalent circuit model, the impedance testing equipment can use the measured phase angle to help determine whether the main parameter is resistance R, inductance L or capacitance C, which is used to mark on the display screen, but will not actively change the parameters set by the user.

[0004] Regardless of the type of impedance testing equipment, users need to determine the device type, capacitor dielectric type, polarity, and approximate measurement range before testing. Furthermore, the setting of certain test parameters during the testing process relies heavily on users consulting relevant standards and manually setting them, resulting in high learning costs and operational barriers. This makes it easy for inaccurate measurements or even device damage to occur due to misjudgment or negligence. Summary of the Invention

[0005] To address the aforementioned technical problems, one objective of this invention is to provide a method for setting test parameters for an impedance testing device. Before using the impedance testing device to test the device under test (DUT), under the premise of ensuring the safe use of the DUT, the impedance testing device automatically acquires the physical properties of the DUT and automatically sets the corresponding test parameters based on these physical properties. This reduces the operational threshold for setting parameters on the impedance testing device and enables safe, accurate, and efficient testing of the DUT.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution: This application relates to a method for automatically setting test parameters of an impedance testing device, including: S1: Set the output impedance mode of the impedance testing equipment to high output impedance mode, and set its measurement range to automatic mode or the highest range. S2: Based on the characteristics of different types of devices under test, different test signals are applied to identify the type of device under test. When a polarized capacitor is detected to be reversed, the impedance test device outputs a reverse connection prompt and stops the test. The test signal includes a DC bias voltage V and an AC signal with an AC signal level V' and a test frequency f. The sum of the peak values ​​Vp corresponding to V and the AC signal level V' is less than the allowable reverse withstand voltage limit V of the device under test when it is a polarized capacitor. lim And when V > 0, V > Vp; S3: Determine the measurement range based on the identified type of the device under test; S4: Based on the type of the device under test and its measurement range, determine the test frequency f0 and the equivalent circuit model using the industry standard built into the impedance testing equipment; S5: Determine the DC bias voltage V0 for testing based on the type of device under test; S6: Determine the AC signal level V0' for testing. When the device under test is a polarized capacitor, V0 is greater than the peak value V0p' corresponding to V0', and the sum of the two is less than the rated voltage V of the device under test. rated ; S7: Obtain the impedance amplitude of the device under test based on V0 and an AC signal with test AC signal level V0' and test frequency f0; S8: Determine the range setting based on the impedance amplitude; S9: Based on the impedance amplitude, the impedance testing equipment switches to a low output impedance mode or maintains a high output impedance mode; S9': Determine whether the measured signal deviates from the matched dynamic range. If yes, fine-tune the AC signal level V0' used for testing and return to S7. If no, end. When the device under test is a polarized capacitor, V0 is greater than the peak value V0p' corresponding to the AC signal level V0', and the sum of the two is less than the rated voltage V of the device under test. rated .

[0007] In some embodiments of this application, S2 includes: S211: Apply a first test signal, the first test signal including a first DC bias voltage V1 and a first AC signal having a first AC signal level V1' and a first test frequency f1, and calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test, wherein V1 > 0 and is greater than the peak value V1p' corresponding to the first AC signal level V1'; S212: Apply a second test signal, the second test signal including a second DC bias voltage V2 and having the first AC signal, and calculate the impedance amplitude |Z2| and impedance angle θ2 of the device under test, where V2=V1+ΔV, ΔV is a preset increment greater than zero, and the sum of V2 and V1p' is less than the reverse withstand voltage limit allowed when the device under test is a polarized capacitor; S213: Based on the impedance amplitudes |Z1|, |Z2| and impedance angles θ1, θ2, determine whether there is a polarized capacitor reversed. If yes, the impedance test equipment outputs a reverse connection prompt and stops the test. If no, proceed to S214. S214: Apply a third test signal, which includes V1 and a second AC signal having V1' and k1*f1, and calculate the impedance amplitude |Z3|, impedance angle θ3, equivalent series resistance ESR3 and loss factor D3 of the device under test, where k1 is a preset coefficient greater than 1. S215: Based on the impedance amplitudes |Z1|, |Z2|, |Z3|, impedance angles θ1, θ2, θ3 and k1, determine the type of the device under test. If the type of the device under test is a resistor or an inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S216. S216: Based on the equivalent series resistances ESR1 and ESR3 and the loss factors D1 and D3, determine whether the device under test is a non-polarized capacitor or a positively connected polarized capacitor, and then proceed to S3.

[0008] In some embodiments of this application, S2 includes: S221: Apply a first test signal, the first test signal including a first DC bias voltage V1 and a first AC signal having a first AC signal level V1' and a first test frequency f1, and calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test, wherein V1 > 0 and is greater than the peak value V1p' corresponding to the first AC signal level V1'; S222: Apply a second test signal, which includes a second DC bias voltage V2 and a second AC signal with V1' and k2*f1, and calculate the impedance amplitude |Z2|, impedance angle θ2 and equivalent series resistance ESR2 of the device under test, where V2=V1+ΔV, ΔV is a preset increment greater than zero, k2 is a preset coefficient greater than 1, and the sum of V2 and V1p' is less than the reverse withstand voltage limit allowed when the device under test is a polarized capacitor; S223: Based on the impedance amplitudes |Z1|, |Z2|, impedance angles θ1, θ2 and k2, determine the type of the device under test and whether there is a polarized capacitor reversed. If the type of the device under test is a resistor or an inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S224. If there is a reverse connection, the impedance test equipment outputs a reverse connection prompt and stops the test. S224: Based on the equivalent series resistances ESR1 and ESR2 and the loss factor D1, determine whether the device under test is a non-polarized capacitor or a positively connected polarized capacitor, and then proceed to S3.

[0009] In some embodiments of this application, S2 includes: S231: Apply a first test signal, the first test signal including a first DC bias voltage V1 and a first AC signal having a first AC signal level V1' and a first test frequency f1, and calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test, wherein V1 > 0, V1 is greater than the peak value V1p' corresponding to the first AC signal level V1', and the sum of V1 and V1p' is less than the reverse withstand voltage limit allowed when the device under test is a polarized capacitor; S232: Apply a second test signal, the second test signal including the first DC bias voltage V1 and a second AC signal having V1' and k3*f1, and calculate the impedance amplitude |Z2|, equivalent series resistance ESR2 and loss factor D2 of the device under test, where k3 is a preset coefficient greater than 1; S233: Based on the impedance amplitudes |Z1|, |Z2|, impedance angles θ1, k2, and equivalent series resistances ESR1 and ESR2, determine the type of the device under test and whether there is a polarized capacitor reversed. If the type of the device under test is a resistor or inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S224. If there is a reverse connection, the impedance test equipment outputs a reverse connection prompt and stops the test. S234: Based on the equivalent series resistances ESR1 and ESR2 and the loss factor D1, determine whether the device under test is a non-polarized capacitor or a positively connected polarized capacitor, and then proceed to S3.

[0010] In some embodiments of this application, S2 includes: S241: Apply a first test signal, the first test signal including a first AC signal level V1' and a first test frequency f. 11 The first AC signal is used to calculate the impedance angle θ1 of the device under test, where the peak value V1p' corresponding to the first AC signal level V1' is less than the allowable reverse withstand voltage limit V when the device under test is a polarized capacitor. lim ; S242: Based on the impedance angle θ1, determine the type of the device under test. If the type of the device under test is a resistor or an inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S243. S243: Apply a second test signal, the second test signal including a first DC bias voltage V1 and a first AC signal, and calculate the loss factor D1 of the device under test, wherein V1 > 0, V1 > V1p', and V1 + V1p' < V lim ; S244: Apply a third test signal, the third test signal including a second DC bias voltage -V1 and the first AC signal, and calculate the loss factor D2 of the device under test; S245: Based on the loss factors D1 and D2, determine whether the device under test is a non-polarized capacitor, a positively connected polarized capacitor, or a reverse-connected capacitor. If the device under test is a non-polarized capacitor or a positively connected polarized capacitor, proceed to S3. If it is a reverse-connected capacitor, the impedance testing equipment outputs a reverse connection prompt and stops the test.

[0011] In some embodiments of this application, S2 includes: S251: Apply a first test signal, the first test signal including a first DC bias voltage V11 and having a first AC signal level V1' and a first test frequency f. 11 The first AC signal is used to calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test, where V11 > 0 and V11 is greater than the peak value V1p' corresponding to the first AC signal level V1'. S252: Apply a second test signal, which includes a second DC bias voltage V21 and the first AC signal, and calculate the impedance amplitude |Z2| and impedance angle θ2 of the device under test, where V21 = V11 + ΔV, ΔV is a preset increment greater than zero, and the sum of V21 and V1p' is less than the allowable reverse withstand voltage limit V when the device under test is a polarized capacitor. lim ; S253: Based on the impedance amplitudes |Z1|, |Z2|, and impedance angles θ1, θ2, determine the type of the device under test and whether there is a polarized capacitor reversed. If the type of the device under test is a resistor or an inductor, proceed to S3. If there is a reverse connection, the impedance test equipment outputs a reverse connection prompt and stops the test. If the type of the device under test is a capacitor and it is connected in the correct direction, proceed to S254. S254: Apply a third test signal, which includes the first DC bias voltage V11 and a second AC signal having V1' and f1 / k4, and calculate the impedance amplitude |Z3|, impedance angle θ3, equivalent series resistance ESR3 and loss factor D3 of the device under test, where k4 is a preset coefficient greater than 1. S255: Based on the equivalent series resistances ESR3 and ESR1, and the loss factors D3 and D1, determine whether the positively connected capacitor is a non-polarized capacitor or a polarized capacitor, and proceed to S3.

[0012] In some embodiments of this application, in step S5, the DC bias voltage V0 for testing is determined according to the type of the device under test, specifically as follows: When the device under test is a resistor, inductor, or a non-polarized capacitor unaffected by DC voltage, V0 = 0; When the device under test is a non-polarized capacitor that is sensitive to DC electric field, V0 is selected as the user-preset DC bias voltage or the default DC bias voltage of the impedance test equipment. When the device under test is a polarized capacitor, V0 is chosen to be greater than V0p' and the sum of the two is less than V. rated The value of .

[0013] In some embodiments of this application, S9 specifically refers to: When the impedance amplitude reaches the upper limit of the preset impedance amplitude threshold, the impedance testing device maintains the current high output impedance mode, so that the output impedance of the impedance testing device is a high output impedance. When the impedance amplitude reaches the lower limit of the preset impedance amplitude threshold, the impedance testing device switches the current high output impedance mode to low output impedance mode, so that the output impedance of the impedance testing device is low output impedance.

[0014] In some embodiments of this application, the test AC signal level V0' is fine-tuned in S9', specifically as follows: Increase or decrease the AC signal level V0' used for testing so that the signal under test falls within the matched dynamic range, wherein the matched dynamic range refers to the range corresponding to 60% to 90% of the full scale of the analog-to-digital converter in the impedance testing equipment.

[0015] The impedance testing equipment test parameter setting methods provided in this application have the following advantages and beneficial effects: (1) Before confirming the type of the device under test, first modulate the output impedance of the impedance testing equipment to the maximum. In this way, when the device under test is in a low impedance abnormal state due to reverse connection, the high output impedance can effectively limit the current flowing into the device, minimize energy injection, prevent local overheating or accelerated electrochemical reaction, and provide the first hardware-level current limiting protection for the entire test process from the energy level. (2) Set the measurement range of the impedance testing equipment to automatic mode or the highest range to prevent signal overload that may occur due to unknown device impedance; (3) By taking advantage of the inherent physical characteristics of different types of devices under test, the type of device under test can be identified with a basis. Driven by the physical laws of the inherent characteristics of the device, it has strong universality. Moreover, when identifying polarized capacitors in reverse connection, there is no need to set an absolute threshold for different models or capacities of capacitors, thus avoiding the risk of misjudgment caused by empirical thresholds. (4) When a polarized capacitor is detected to be reverse connected, the impedance test equipment outputs a reverse connection prompt to remind the user in a timely manner. When a polarized capacitor is reverse connected, the test is stopped immediately to provide time-limited protection for the device under test. (5) After determining the type of the device under test, the measurement range, test frequency, equivalent circuit model, output impedance, DC bias voltage and AC signal level are determined in sequence according to the test parameter determination principle and industry standards. This achieves coordinated optimization of test parameters, maximizes the signal-to-noise ratio and accuracy of the final measurement, and the impedance test equipment has built-in industry standards. Based on this, test parameters that conform to industry standards can be automatically obtained without any professional judgment or manual input from the user. Each measurement conforms to industry standards, improving accuracy. (6) When applying a DC bias voltage greater than zero, the DC bias voltage must be greater than the peak value corresponding to the AC signal level to ensure that the voltage across the device is always positive when the device is correctly connected and there is no reverse voltage. The sum of the two is less than the reverse withstand voltage limit allowed when the device under test is a polarized capacitor. This ensures that even if the device is mistakenly reverse connected, the maximum reverse voltage it withstands is far below the damage threshold, thus providing a second voltage limiting protection for the device under test from the voltage amplitude level.

[0016] This application also relates to an impedance testing device and a testing method for testing devices, the impedance testing device and the testing method comprising: The test parameters of the impedance testing equipment for the device under test are determined using the impedance testing equipment test parameter setting method described above. Using the determined test parameters, a test signal is applied to the device under test, and the test results are displayed on the impedance testing equipment.

[0017] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart illustrating an embodiment of a method for setting test parameters for an impedance testing device when the impedance testing device is an LCR meter; Figure 2 This illustrates the flow chart of step S2 in an embodiment of the impedance testing device parameter setting method when the impedance testing device is an LCR meter. Figure 1 ; Figure 3 This illustrates the flow chart of step S2 in an embodiment of the test parameter setting method when the impedance testing device is an LCR meter. Figure 2 ; Figure 4 This illustrates the flow chart of step S2 in an embodiment of the test parameter setting method when the impedance testing device is an LCR meter. Figure 3 ; Figure 4 This illustrates the flow chart of step S2 in an embodiment of the test parameter setting method when the impedance testing device is an LCR meter. Figure 6 ; Figure 5 This illustrates the flow chart of step S2 in an embodiment of the test parameter setting method when the impedance testing device is an LCR meter. Figure 7 ; Figure 1 The flowchart shows the test method for impedance testing equipment when the impedance testing equipment is an LCR meter. Detailed Implementation

[0020] 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.

[0021] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. In the description of this invention, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0022] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. In the description of the above embodiments, specific features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples.

[0023] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0024] Impedance testing equipment is used to test inductors, resistors, and capacitors. Several core test parameters (including test frequency, DC bias voltage, AC signal level, equivalent circuit model, measurement range, and output impedance) have a decisive impact on the measurement results. These test parameters cannot be arbitrarily selected but are determined by the physical structure, operating characteristics, and application scenario of the device under test. Incorrect test parameter settings will directly lead to inaccurate and incomparable measurement results, and may even damage the device under test.

[0025] The following will explain the significance of test frequency, equivalent circuit model, DC bias voltage, AC signal level, measurement range, and output impedance for the testing of the device under test from a theoretical perspective.

[0026] (1) Test frequency Different devices under test (DUTs) require measurements at different test frequencies to obtain meaningful parameter values. The selection criteria for test evaluation include the characteristics of the equivalent circuit, industry standards and specifications, and the actual operating frequency.

[0027] For example, large-capacity aluminum electrolytic capacitors (>10μF) require a test frequency of 100Hz or 120Hz. An aluminum electrolytic capacitor is internally composed of an anode foil, electrolyte, and cathode foil, and its equivalent circuit includes capacitance C, equivalent series resistance (ESR), and parasitic inductance L. At frequencies above 1kHz, the parasitic inductance L and capacitance C form a series resonance, and the measured "capacitance" is actually the effective capacitance near the resonance point, which will be significantly lower than the nominal capacitance. For example, an aluminum electrolytic capacitor nominally rated at 100μF might measure 98μF at 100Hz, but at 1kHz it might only show 85μF or even lower. Furthermore, industry standards (e.g., IEC 60384-4 "Fixed capacitors for electronic equipment - Part 4: Specifications for solid and non-solid electrolyte aluminum capacitors", GB / T 25121) uniformly stipulate 100Hz / 120Hz as the verification frequency for the nominal capacitance of aluminum electrolytic capacitors; only capacitance values ​​measured at this frequency can be directly compared with the specifications. From a practical application perspective, these types of capacitors are mainly used in power frequency rectifier filter circuits, and 100Hz / 120Hz is their actual operating frequency.

[0028] Tantalum electrolytic capacitors (≤10μF) are commonly tested at 1kHz. Tantalum electrolytic capacitors use a solid MnO2 or conductive polymer cathode, resulting in a lower equivalent series resistance (ESR) and superior high-frequency characteristics compared to aluminum electrolytic capacitors. IEC 60384-3, "Fixed capacitors for electronic equipment – ​​Part 3: Specifications for solid electrolyte tantalum capacitors," specifies a standard test frequency of 1kHz (below 10μF). The capacitance value at 1kHz more accurately reflects its effective capacitance in high-frequency decoupling applications.

[0029] Small-capacity ceramic / film capacitors (<1nF) require measurements at 100kHz or even 1MHz. These capacitors have extremely small capacitance values ​​and very high capacitive reactance at low frequencies. For example, a 1nF capacitor has a capacitive reactance of approximately 1.6MΩ at 100Hz, which is close to or exceeds the upper limit of the measurement range of most impedance testing equipment, resulting in severely insufficient measurement accuracy or unstable readings. Increasing the frequency to 100kHz reduces the capacitive reactance of the same capacitor to approximately 1.6kΩ, entering the optimal measurement range of the impedance testing equipment. Furthermore, these capacitors are commonly used in high-frequency circuits, and their nominal capacitance values ​​are calibrated at high frequencies.

[0030] Medium-capacitance ceramic capacitors (1nF~1μF) are commonly used at 1kHz or 10kHz. This range is the optimal range for impedance testing equipment, and the actual operating frequency of this type of capacitor is mostly in the audio to radio frequency range.

[0031] (2) Equivalent circuit model (series / parallel) Actual capacitors and inductors are not ideal components and always have parasitic resistance. Impedance testing equipment typically presents measurement results using a two-component model of "ideal component + equivalent parasitic resistance." The correct model must be selected based on the impedance characteristics of the device under test.

[0032] For example, large capacitors should use the series equivalent model (Cs). Large capacitors have low capacitive reactance (e.g., 100μF has a capacitive reactance of approximately 16Ω at 100Hz), and the equivalent series resistance (ESR) contributes significantly to the overall impedance. Furthermore, ESR is a key indicator of electrolytic capacitor quality and must be directly presented. The series equivalent model directly provides the capacitance (Cs) and equivalent series resistance (ESR), intuitively reflecting the true characteristics of the device. If the parallel equivalent model (Cp) is incorrectly used, the effect of ESR will be converted into parallel leakage resistance, which will not directly provide an ESR value and may also cause the capacitance reading to deviate.

[0033] Small capacitors should be modeled using a parallel equivalent (Cp) model. Small capacitors have extremely high capacitive reactance (e.g., 100pF has a capacitive reactance of approximately 1.6MΩ at 1kHz), and their parasitic leakage resistance Rp is connected in parallel (Rp is also called the equivalent parallel resistance), having a more fundamental impact on the overall impedance. The parallel equivalent model directly provides Cp and Rp, more closely reflecting the physical nature of the device under test. Using a series equivalent model would amplify the minute leakage current effect into an unreliable ESR value.

[0034] Similarly, for inductors with a minimum inductance of approximately 1H, the series equivalent model (Ls) is used for inductances with smaller inductance below this value, while the parallel equivalent model (Lp) is used for inductances with larger inductance above this value and significant inter-turn capacitance.

[0035] (3) DC bias voltage For example, polarized capacitors (e.g., aluminum electrolytic, tantalum electrolytic) must be subjected to a positive DC bias voltage. The anodic oxide film (Al₂O₃ or Ta₂O₅) of these capacitors is formed electrochemically and requires a DC bias voltage to maintain its integrity and low leakage current. Under zero bias, the oxide film is in a "not sufficiently polarized" state, resulting in a higher leakage current and potentially lower measured capacitance and higher losses. Even if the applied AC current signal is symmetrical, it cannot replace the polarization effect of the DC bias voltage. More seriously, once a reverse DC bias voltage is applied, the oxide film undergoes an irreversible reduction reaction with the electrolyte, forming a conductive path, leading to a surge in leakage current or even a short circuit. Standard testing requires a superimposed positive DC bias voltage (typically 1% to 10% of the rated voltage, at least tens of mV).

[0036] Class II ceramic capacitors (X7R, X5R, etc.) require a DC bias voltage to simulate actual operating conditions. These capacitors use ferroelectric materials such as barium titanate as the dielectric, exhibiting significant DC bias voltage characteristics—the effective dielectric constant of the dielectric decreases significantly as the applied DC bias voltage increases. For example, an X7R capacitor nominally rated at 10μF may measure 10μF at 0V bias, but might only have 4μF at 5V bias. In actual circuits, these capacitors typically operate under a certain DC bias voltage; therefore, measurements must be taken under a DC bias voltage to obtain the true effective capacitance.

[0037] (4) AC signal level The selection of AC signal level must take into account both the signal-to-noise ratio and the voltage sensitivity of the device under test. If the level is too low, the measurement signal is easily drowned out by noise; if the level is too high, it may exceed the rated voltage of the device or cause stress to sensitive components.

[0038] For polarized capacitors, the peak value of the AC signal level must be matched with the DC bias voltage to ensure that the total instantaneous voltage is never negative. For example, if the DC bias voltage is 50 mV, the peak value of the AC signal level should be less than 50 mV to ensure that the voltage across the device under test is always positive.

[0039] (5) Measurement range The measurement range determines the operating range of the amplifier and detector inside the impedance testing equipment. Impedance testing equipment typically employs a multi-range design, with each range corresponding to a specific impedance measurement range. If the range is too large, the measured signal will fall into the low-order range of the analog-to-digital converter within the impedance testing equipment, increasing quantization error and noise, thus reducing measurement accuracy. If the range is too small, the measured signal may exceed the range, causing amplifier saturation, clipping distortion, and completely incorrect results. Therefore, the set measurement range must be matched to the actual impedance of the device under test.

[0040] (6) Output impedance Output impedance determines the ability of an impedance testing device to deliver energy to the device under test. Impedance testing devices typically offer at least two output impedance modes: a high output impedance mode (e.g., 100Ω) and a low output impedance mode (e.g., 30Ω or lower).

[0041] In high output impedance mode, the equivalent output impedance of the impedance testing equipment is relatively large, forming a voltage divider relationship with the device under test (DUT). When the DUT impedance is low, the voltage actually applied across the DUT is attenuated by the voltage divider, and the output current is also limited. This characteristic is crucial in the preliminary detection stage of unknown device physical properties: if the DUT exhibits a low impedance anomaly due to reverse connection, the high output impedance can effectively limit the current flowing into the DUT, minimizing energy injection and preventing local overheating or accelerated electrochemical reactions.

[0042] In low output impedance mode, impedance testing equipment has stronger driving capability, can more accurately apply the set voltage to the two ends of the device under test, and has a better signal-to-noise ratio, making it suitable for precision measurements. However, for devices under test with abnormally low impedance, low output impedance cannot limit the current, which may cause a large current surge.

[0043] To achieve "one-click" safe and accurate setting of impedance testing equipment test parameters, this application relates to an impedance testing equipment test parameter setting method, which can automatically acquire the physical properties of the device under test and automatically set accurate test parameters for the impedance testing equipment based on the physical properties, avoiding manual judgment and operation, improving the measurement results of the impedance testing equipment, and simultaneously constructing a safety detection method to ensure that the device under test is safe before testing.

[0044] Before setting the test parameters, let's first describe the underlying physical principles involved in this application.

[0045] (1) Principle for distinguishing between non-polarized and polarized capacitors Non-polarized capacitors (e.g., ceramic, thin film) have metal electrodes, and their ESR is composed of metal resistance, which is almost unchanging with frequency and has an extremely low absolute value (mΩ level). Therefore, the low-frequency loss factor D1 is extremely small (<0.01). Polarized capacitors (e.g., aluminum electrolytic, tantalum) have electrolyte cathodes, and the resistance generated by ionic conduction dominates the ESR. As the frequency increases, the ionic relaxation effect weakens, and the ESR decreases significantly (usually by more than 30%). Furthermore, at low frequencies, there is already inherent loss due to ionic conduction (loss factor D1 ≥ 0.01).

[0046] By comparing the ESR change rate and the low-frequency loss factor D1 level at two frequencies, the non-polarized / polarized capacitors can be reliably distinguished. It should be noted that this distinction is for matching the optimal test parameters. Even if a very small number of special capacitors (such as some high-capacity, high-voltage MLCCs) are in the fuzzy boundary, it will only lead to the selection of conservative test parameters and will never cause safety risks or device damage.

[0047] (2) Principle of reversing polarity of capacitor The anodic oxide film of a polarized capacitor exhibits unidirectional conductivity. Under forward bias, it presents high impedance. However, once subjected to reverse bias (even by only tens of mV), the oxide film undergoes an electrochemical reaction with the electrolyte, causing a sharp decrease in the equivalent parallel resistance Rp. This results in a significant reduction in the impedance amplitude |Z| during AC measurements, and a shift in the phase angle θ from -90° to 0° (a sudden increase in loss). This is an intrinsic electrochemical characteristic of polarized capacitors, independent of capacitance and model. Therefore, no preset threshold is needed; reverse connection can be detected solely by the inherent trend of the change.

[0048] (3) The principle of distinguishing between resistor R, inductor L, and capacitor C The three components respond to frequency according to different physical laws: the capacitance amplitude is inversely proportional to the frequency (|Z|∝1 / f), the resistance impedance is independent of the frequency, and the inductor impedance amplitude is directly proportional to the frequency (|Z|∝f).

[0049] By comparing the impedance ratio at two different frequencies, the three types of components can be strictly distinguished.

[0050] (4) Output impedance safety and accuracy principle When the impedance of the device under test (DUT) becomes abnormally low, the high output impedance limits the voltage and current actually applied to the DUT through its internal resistance voltage division, thus suppressing energy injection; the low output impedance can more accurately transmit the set voltage to the low impedance device, improving the signal-to-noise ratio.

[0051] (5) The optimal output impedance should match the impedance of the device under test. When the device under test (DUT) has high impedance, use high output impedance to reduce the load effect; when the DUT has low impedance, use low output impedance to ensure driving capability.

[0052] Meanwhile, the measurement range should be selected so that the measured signal falls within the optimal dynamic range of the analog-to-digital converter to ensure measurement accuracy.

[0053] The impedance testing equipment parameter setting method involved in this application follows the logic of "safety detection - attribute identification - test parameter selection", which ensures that the device under test is under safe constraints throughout the process and automatically and accurately completes the setting of test parameters.

[0054] In some embodiments of this application, as described above, it is necessary to ensure that the type of the device under test has been distinguished before selecting test parameters (if the device under test is a capacitor, polarity and non-polarity have also been distinguished).

[0055] Figure 1 The specific process of setting test parameters for impedance testing equipment is shown below, which will be combined with... Figure 2 The following details the method for setting the test parameters of the impedance testing equipment.

[0056] In some embodiments of this application, the impedance testing device can be an impedance analyzer, LCR meter, or other electronic device capable of measuring R / L / C.

[0057] For ease of description, the following explanation will use an LCR meter as an example of impedance testing equipment.

[0058] S1: Set the output impedance mode of the LCR meter to high output impedance mode and set its measurement range to automatic mode or the highest range.

[0059] When testing a device, it is first necessary to ensure the safety of the device under test. In some embodiments of this application, the device under test is protected from three aspects: voltage constraint, energy constraint and time constraint.

[0060] In some embodiments of this application, the output impedance of the LCR meter is adjusted to the maximum to ensure protection of the device under test at the energy constraint level.

[0061] Adjust the output impedance of the LCR meter to its maximum, forcing the output impedance mode to high output impedance mode (e.g., 100Ω). The output impedance of the LCR meter determines its ability to deliver energy to the device under test (DUT). At high output impedance, the equivalent output impedance of the LCR meter is larger, forming a voltage divider relationship with the DUT. When the DUT exhibits an abnormal low impedance state due to reverse connection (e.g., reverse-connected polarized capacitors), the high output impedance effectively limits the current flowing into the device, minimizing energy injection, preventing localized overheating or accelerated electrochemical reactions, and achieving active energy-level protection.

[0062] This high output impedance mode is maintained until S9. Only after the properties of the device under test are accurately identified and the connection direction is determined safely will the output impedance be switched according to the output impedance determined in S9 (i.e., high impedance devices are matched with high output impedance, and low impedance devices are matched with low output impedance). In this way, the device under test is protected at the energy level during the determination of test parameters.

[0063] In some embodiments of this application, the measurement range of the LCR meter is set to automatic mode or the highest range to prevent signal overload that may occur due to unknown device impedance.

[0064] In some embodiments of this application, a clear prompt may be displayed on the LCR meter screen: "Polarized devices cannot be reversed! Please follow the markings: positive terminal to H, negative terminal to L." This prompt guides users to connect according to a unified standard, reducing the cognitive burden of operation.

[0065] S2: Based on the characteristics of different types of devices under test, different test signals are applied to identify the type of device under test, and the LCR meter outputs a reverse connection prompt when a polarized capacitor is detected to be connected in reverse.

[0066] Different types of devices under test have different characteristics. Therefore, different types of devices under test have different underlying physical principles as described above, which serve as the basis for identifying the type of device under test.

[0067] A test signal is applied to the device under test. The test signal includes a DC bias voltage V, an AC signal with an AC signal level V' and a test frequency f.

[0068] Among them, the DC bias voltage V, the AC signal level V', and the test frequency f are all preset by the user based on operating experience or test standards. However, since it is unknown whether the device under test has a polarized capacitor connected in reverse, it is necessary to limit the voltage across its two ends to protect the device under test through voltage constraints.

[0069] In some embodiments of this application, the voltage constraint can be that the sum of the peak value Vp corresponding to the DC bias voltage V and the AC signal level V' is less than the allowable reverse withstand voltage limit V when the device under test is a polarized capacitor. lim (For example, 0.1V or 0.05V, which can be empirical values), and V>Vp when a positive DC bias voltage (i.e. V>0) is present.

[0070] When V > 0, V > Vp, ensuring that the instantaneous voltage applied to the device under test remains positive. The physical meaning of this constraint is that if the user connects the device under test correctly as indicated (i.e., positive terminal connected to H), the minimum instantaneous voltage across the device under test is V - Vp, which is always greater than zero, meaning the voltage is always positive. For correctly connected polarized capacitors, their anodic oxide film always bears a positive voltage and will never experience reverse bias, maintaining the integrity and stability of the oxide film.

[0071] For polarized capacitors, a positive DC bias voltage needs to be applied, and to prevent damage from reverse connection, V+Vp < V. lim This ensures that even in the event of reverse polarity of a capacitor, the output impedance in S1 is already modulated to the maximum, resulting in a small test current flowing into the device. Furthermore, the test time is generally short (e.g., in the millisecond range). Therefore, a brief period of negative voltage will not pose a risk of fire or explosion. Once a reverse polarity is detected, the user is immediately alerted and the test is stopped immediately, minimizing the duration of continuous negative voltage applied to the device under test and protecting the device under test from a time constraint perspective.

[0072] In some embodiments of this application, different test signals are applied to the device under test, corresponding to different identification processes.

[0073] Figure 2 A flowchart illustrating a first embodiment of the S2 identification process is shown, in conjunction with Figure 3 The specific description is as follows.

[0074] S211: Apply a first test signal, which includes a first DC bias voltage V1 and a first AC signal having a first AC signal level V1' and a first test frequency f1, and calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test.

[0075] In some embodiments of this application, the first AC signal is denoted as V1'@f1, and the peak value corresponding to V1' (referring to the amplitude of the AC test excitation signal applied to the device under test by the LCR meter, usually referring to the effective value of the AC signal) is V1p' (i.e., 1.414×V1').

[0076] As described above, the first DC bias voltage V1 and the first AC signal can be selected as follows: V1 > 0 and V1 > V1p'.

[0077] The first test frequency f1 can be chosen empirically at a lower frequency (e.g., 100Hz). This is because, in the subsequent determination of reverse connection of polarized capacitors, the reverse leakage resistance needs to be utilized to lower the impedance (i.e., at low frequencies, the capacitive reactance of the device is larger, and the effect of the parallel leakage resistance on the total impedance is more significant), thereby improving the sensitivity of the reverse connection determination. At the same time, low frequency is also one of the key frequencies for distinguishing between electrolytic capacitors and ceramic capacitors.

[0078] In some embodiments of this application, the test frequency f1 can be set by default to one-tenth or about one-tenth of the highest test frequency of the LCR meter, so as to provide more room for subsequent selection of higher frequencies and avoid the risk of damage to the device under test due to reverse connection caused by excessively low frequency and extended test time.

[0079] In some embodiments of this application, after applying V1 of 20mV and V1'@f1 of 10mV@100Hz, the LCR meter can measure the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1, and loss factor D1 of the output device under test.

[0080] S212: Apply a second test signal, which includes a second DC bias voltage V2 and a first AC signal, and calculate the impedance amplitude |Z2| and impedance angle θ2 of the device under test.

[0081] In S212, V2 = V1 + ΔV, where ΔV is a preset increment greater than zero. ΔV can be 1 to 3 times V1. In some embodiments of this application, ΔV is 1.5 times V1 (that is, ΔV is 30mV), so V2 is 50mV.

[0082] When setting V2, it is necessary to consider that the sum of V2 and V1p' is less than the allowable reverse withstand voltage limit V when the device under test is a polarized capacitor. lim In V2+V1p'<V lim At that time, it also satisfies that V1p' < V in S211. lim .

[0083] In some embodiments of this application, after applying V2 of 50mV and V1'@f1 of 10mV@100Hz, the LCR meter is able to measure the impedance amplitude |Z2| and impedance angle θ2 of the output device under test.

[0084] S213: Based on the impedance amplitudes |Z1|, |Z2| and impedance angles θ1, θ2, determine whether there is a polarized capacitor reversed. If yes, the LCR meter outputs a reversed connection warning and stops the test. If no, proceed to S214.

[0085] In some embodiments of this application, S213 utilizes the unique electrical response characteristics of a polarized capacitor under reverse bias for determination. The anodic oxide film of a polarized capacitor has unidirectional conductivity: it exhibits high impedance and minimal leakage current under forward bias. However, once subjected to reverse bias (even if only tens of mV), an irreversible reduction reaction occurs at the interface between the oxide film and the electrolyte, forming a conductive microchannel, which causes a sharp decrease in the equivalent parallel resistance Rp.

[0086] In AC impedance measurement, the sudden drop in equivalent parallel resistance Rp will inevitably cause two observable measurement phenomena: (1) the impedance amplitude |Z1| is significantly reduced due to being pulled down by the equivalent parallel resistance Rp; (2) the loss angle increases significantly, which is manifested as the impedance angle shifting significantly from -90° to 0° (i.e., the capacitive characteristics are weakened and the resistive characteristics are enhanced).

[0087] These two changes are intrinsic physical responses of polarized capacitors in reverse connection, which are independent of the capacitance size and specific model of the capacitor. Therefore, there is no need to set different thresholds for different models or capacitances of capacitors, which is highly universal and avoids the risk of misjudgment caused by thresholds.

[0088] Therefore, based on the impedance amplitudes |Z1| and |Z2| and the impedance angles θ1 and θ2, the following three conditions are used to determine the reverse connection. (1) The first condition is that θ1≈-90°. This condition is used to exclude resistors and inductors. The impedance angle of a resistor is 0° and the impedance angle of an inductor is +90°. Only capacitors may experience a subsequent decrease in impedance and a phase shift when reversed. (2) The second condition is that |Z2| is significantly smaller than |Z1|. When the forward DC bias voltage of a capacitor increases slightly, the impedance remains almost unchanged. However, when reversed, the forward DC bias voltage increases from V1 to V1+ΔV, which means that the reverse bias voltage increases from -V1 to -(V1+ΔV). The increase in reverse voltage causes the equivalent parallel resistance Rp to drop sharply. The parallel effect makes the total impedance amplitude decrease significantly. This change is much greater than the normal parameter shift caused by the change in forward DC bias voltage. (3) The third condition is that θ2 is significantly shifted towards 0° compared to θ1. The decrease in equivalent parallel resistance Rp caused by reverse connection not only reduces the impedance amplitude but also alters the impedance phase characteristics. An ideal capacitor has an impedance angle of -90° (i.e., current leads voltage by 90°). When the equivalent parallel resistance Rp decreases, the resistive current component increases, the phase difference between the total current and voltage decreases, and the impedance angle shifts from -90° to 0°. The magnitude of this shift is positively correlated with the degree of leakage current.

[0089] Therefore, when the above three conditions are met, it is determined that a polarized capacitor is reverse-connected. At this time, the LCR meter immediately outputs a reverse connection warning, for example, by issuing an alarm sound and forcibly stopping subsequent tests, or by displaying the text message "A polarized capacitor is reverse-connected. Please check the device identification."

[0090] If the above three conditions are not met simultaneously, it means that there is no polarized capacitor reversed, that is, the device under test is an inductor, resistor or capacitor with the correct connection direction (i.e., a capacitor connected in the correct direction). Then proceed to S214.

[0091] In S214 to S216, the inherent differences in impedance-frequency characteristics of three types of passive devices—resistors, inductors, and capacitors—are utilized to automatically distinguish the type of the device under test. Furthermore, capacitors are subdivided into non-polarized capacitors and polarized capacitors, providing sufficient basis for the selection of test parameters for subsequent precision measurements.

[0092] S214: Apply a third test signal, which includes V1 and a second AC signal with V1' and k1*f1, and calculate the impedance amplitude |Z3|, impedance angle θ3, equivalent series resistance ESR3 and loss factor D3 of the device under test.

[0093] The second AC signal is denoted as V1'@k1*f1, where k1 is a preset coefficient greater than 1, for example, k1∈(5,50). The selection of k1 needs to consider two conditions: (1) the difference between the frequencies of f1 and k1*f1 is large enough to reliably distinguish the impedance ratio of the three types of devices (R / L / C); (2) k1*f1 should not be too high, otherwise large-capacity electrolytic capacitors may enter the resonant region affected by parasitic inductance, causing the impedance-frequency relationship to deviate from pure capacitive. 1kHz is still in the capacitive-dominated range for most electrolytic capacitors, therefore, k1 can be selected as 10.

[0094] In some embodiments of this application, after applying V1 of 20mV and V1'@f1 of 10mV@1kHz, the LCR meter can measure the impedance amplitude |Z3|, impedance angle θ3, equivalent series resistance ESR3, and loss factor D3 of the output device under test.

[0095] S215: Based on the impedance amplitudes |Z1|, |Z2|, |Z3|, impedance angles θ1, θ2, θ3 and k1, determine the type of the device under test. If the type of the device under test is a resistor or an inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S216.

[0096] For a resistor, its impedance is independent of the frequency and voltage of the applied signal. Therefore, no matter how the frequency and voltage change in S211, S212, and S214, its impedance amplitude and impedance angle remain unchanged (there is no absolute constant; fluctuations within a small range are considered constant). Therefore, if |Z1|≈|Z2|≈|Z3| and θ1≈θ2≈θ3≈0°, the device under test is a resistor.

[0097] For an inductor, its impedance amplitude is directly proportional to the frequency. When the frequency changes from f1 to k1*f1, its impedance amplitude also increases by a factor of k1, and changes in DC voltage bias do not affect the inductor impedance. Therefore, |Z3|≈k1*|Z1|≈k1*|Z2|. The voltage of an ideal inductor leads the current by 90°; therefore, the impedance angle is θ1≈θ2≈θ3≈+90°.

[0098] For a capacitor, its impedance amplitude is inversely proportional to the frequency, and the change in DC voltage bias has a negligible effect on the capacitor impedance. Therefore, |Z3|≈|Z1| / k1≈|Z2| / k1. The voltage of an ideal capacitor always lags the current by 90° and does not change with the frequency. Therefore, θ1≈θ2≈θ3≈-90°.

[0099] In this way, the classification of types can be completed.

[0100] S216: Based on the equivalent series resistances ESR1 and ESR3 and the loss factors D1 and D3, determine whether the device under test is a non-polarized capacitor or a polarized capacitor with positive connection, and then proceed to S3.

[0101] After determining the capacitor type, it is necessary to further classify them into polarized capacitors or non-polarized capacitors, because the test frequency, equivalent circuit model, and DC voltage bias selected in subsequent measurements are completely different for the two types of capacitors.

[0102] Before making a determination, we first describe the physical characteristics of whether or not a polarized capacitor exists.

[0103] Physical characteristics of nonpolar capacitors: Their electrodes are metals (silver, copper, aluminum, etc.), and their ESR is mainly composed of the resistance of the metal conductor and the resistance of the leads. The resistivity of the metal conductor is not sensitive to frequency, so the ESR hardly changes with frequency (rate of change < rate of change threshold (e.g., 30%)). At the same time, the absolute value of the metal resistance is extremely low (mΩ level), resulting in a very small loss factor D at low frequencies (< coefficient threshold (e.g., 0.01)). Although dielectric loss also contributes a portion, it is far less than the contribution of the metal resistance in the 100Hz to 1kHz range.

[0104] The physical characteristics of a polarized capacitor are: its cathode is an electrolyte (liquid electrolyte or solid MnO2 / conductive polymer). The conductivity mechanism of the electrolyte is ion migration, and the ion relaxation effect causes the equivalent resistance to decrease significantly with increasing frequency (rate of change ≥ rate of change threshold (e.g., 30%)). At low frequencies (100Hz), the ion movement amplitude is large and energy dissipation is high, resulting in a high ESR and a non-negligible loss factor D (≥ coefficient threshold (e.g., 0.01)). At high frequencies (1kHz), the ion movement amplitude decreases, and both ESR and loss factor D decrease.

[0105] Therefore, based on the physical characteristics described above, the presence or absence of polarized capacitors can be distinguished by the equivalent series resistance (ESR) and the loss factor (D).

[0106] In S216, ESR1 and D1 are obtained at low frequency f1, while ESR3 and D3 are obtained at high frequency k1*f1.

[0107] Based on this, if |ESR1-ESR3| / ESR1<30% and D1<0.01, it is determined to be a non-polarized capacitor; if |ESR1-ESR3| / ESR1≥30% and D1≥0.01, it is determined to be a polarized capacitor.

[0108] Figure 3 A flowchart describing a second embodiment of the recognition process is provided, in conjunction with... Figure 4 The description is as follows.

[0109] S221: Apply a first test signal, which includes a first DC bias voltage V1 and a first AC signal having a first AC signal level V1' and a first test frequency f1, and calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test.

[0110] As described in S211 above, the first AC signal is denoted as V1'@f1, and the peak value corresponding to V1' is V1p', ensuring that V1 > 0 and V1 > V1p'. Furthermore, f1 is selected as 100Hz.

[0111] In some embodiments of this application, after applying V1 of 20mV and V1'@f1 of 10mV@100Hz, the LCR meter can measure the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1, and loss factor D1 of the output device under test.

[0112] S222: Apply a second test signal, which includes a second DC bias voltage V2 and a second AC signal with V1' and k2*f1, and calculate the impedance amplitude |Z2|, impedance angle θ2 and equivalent series resistance ESR2 of the device under test.

[0113] The second AC signal is denoted as V1'@k2*f1, and the peak value corresponding to V1' is V1p'. The selection of k2 is similar to the selection of k1 in S214 as described above, and k2 is also selected as 10.

[0114] As stated in S212 above, V2 = V1 + ΔV, and ΔV is chosen to be 30mV. Therefore, V2 is 50mV, and V2 + V1p' < V lim .

[0115] In some embodiments of this application, after applying V2 of 50mV and V1'@k2*f1 of 10mV@1kHz, the LCR meter can measure the impedance amplitude |Z2|, impedance angle θ2, and equivalent series resistance ESR2 of the output device under test.

[0116] S223: Based on the impedance amplitudes |Z1|, |Z2|, impedance angles θ1, θ2 and k2, determine the type of the device under test and whether there is a polarized capacitor reversed. If the type of the device under test is a resistor or inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S224. If there is a reverse connection, the LCR meter will output a reverse connection prompt and stop the test.

[0117] As described in S215, the relationship between the R / L / C devices and the frequency and DC bias voltage can be used to determine the type of the device under test using the following conditions.

[0118] If |Z2| / |Z1| deviates significantly from 1 / k2, and θ2 deviates abnormally towards 0°, it indicates that a polarized capacitor is reverse-connected. The LCR meter will output a reverse connection warning and stop the test. If |Z2|≈|Z1| and θ1≈0°, it indicates that the device under test is a resistor. If |Z2|≈k2*|Z1| and θ1≈+90°, it indicates that the device under test is an inductor. If |Z2|=|Z1| / k2 and θ1≈-90°, it indicates that the device under test is a capacitor and is connected in the correct orientation.

[0119] S224: Based on the equivalent series resistances ESR1 and ESR2 and the loss factor D1, determine whether the device under test is a non-polarized capacitor or a positively connected polarized capacitor, and then proceed to S3.

[0120] Referring to the principle for determining the type of non-polarized and polarized capacitors in S216, the connection direction of the identified capacitor can be determined using the following conditions.

[0121] If |ESR1-ESR2| / ESR1<30% and D1<0.01, it is determined to be a non-polarized capacitor; if |ESR1-ESR2| / ESR1≥30% and D1≥0.01, it is determined to be a polarized capacitor.

[0122] The identification process of S221 to S224 is simpler and faster than that of S211 to S216, making it suitable for high-speed production line applications.

[0123] Figure 4 A flowchart illustrating a third embodiment of the identification process is shown, in conjunction with... Figure 5 The specific description is as follows.

[0124] S231: Apply a first test signal, which includes a first DC bias voltage V11 and a first AC signal having a first AC signal level V1' and a first test frequency f1, and calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test.

[0125] The implementation of S231 is similar to S211 as described above, and will not be repeated here. Here, V11 is selected as 50mV.

[0126] In some embodiments of this application, after applying V11 of 50mV and V1'@f1 of 10mV@100Hz, the LCR meter can measure the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1, and loss factor D1 of the output device under test.

[0127] S232: Apply a second test signal, which includes a first DC bias voltage V11 and a second AC signal with V1' and k3*f1, and calculate the impedance amplitude |Z2|, equivalent series resistance ESR2 and loss factor D2 of the device under test.

[0128] The second AC signal is denoted as V1'@k3*f1, and the peak value corresponding to V1' is V1p'. It is ensured that V1 > 0 and V1 > V1p'. The selection of k3 is similar to the selection of k1 in S214 as described above, and k3 is also selected as 10.

[0129] In some embodiments of this application, after applying V11 of 50mV and V1'@k3*f1 of 10mV@1kHz, the LCR meter can measure the impedance amplitude |Z2|, equivalent series resistance ESR2, and loss factor D2 of the output device under test.

[0130] S233: Based on the impedance amplitudes |Z1|, |Z2|, impedance angles θ1, k2, and equivalent series resistances ESR1 and ESR2, determine the type of the device under test and whether there is a polarized capacitor reversed. If the device under test is a resistor or inductor, proceed to S3. If the device under test is a capacitor, proceed to S224. If there is a reverse connection, the LCR meter will output a reverse connection prompt and stop the test.

[0131] As described in S215, the relationship between the R / L / C devices and the frequency and DC bias voltage can be used to determine the type of the device under test using the following conditions.

[0132] If ESR1 is abnormally high (e.g., ESR1 / ESR2 > preset threshold (e.g., preset threshold is set to 10)), it indicates that a polarized capacitor is reverse-connected. The LCR meter will output a reverse connection warning and stop the test. If |Z2|≈|Z1| and θ1≈0°, it indicates that the device under test is a resistor. If |Z2|≈k3*|Z1| and θ1≈+90°, it indicates that the device under test is an inductor. If |Z2|=|Z1| / k3 and θ1≈-90°, it indicates that the device under test is a capacitor and is connected in the correct direction.

[0133] S234: Based on the equivalent series resistances ESR1 and ESR2 and the loss factor D1, determine whether the device under test is a non-polarized capacitor or a positively connected polarized capacitor, and then proceed to S3.

[0134] Referring to the principle for determining the type of non-polarized and polarized capacitors in S216, the connection direction of the identified capacitor can be determined using the following conditions.

[0135] If |ESR1-ESR2| / ESR1<30% and D1<0.01, it is determined to be a non-polarized capacitor; if |ESR1-ESR2| / ESR1≥30% and D1≥0.01, it is determined to be a polarized capacitor.

[0136] There is no change in DC bias voltage during the identification process from S231 to S234, resulting in better security.

[0137] Figure 5 A flowchart illustrating a fourth embodiment of the identification process is shown, in conjunction with Figure 6 Specifically, it includes the following.

[0138] S241: Apply a first test signal, the first test signal including a first AC signal level V1' and a first test frequency f. 11 The first AC signal is obtained, and the impedance angle θ1 of the device under test is calculated.

[0139] No DC bias voltage is applied in S241, and the first test frequency f 11 The choice is similar to the choice of f1 as described above. In S241, f 11 Select 1kHz.

[0140] In some embodiments of this application, the first AC signal is denoted as V1'@f 11 With a value of 10mV@1kHz, after the first AC signal, the LCR meter can measure the impedance angle θ1 of the output device under test.

[0141] Among them, the peak value V1p' corresponding to V1' is less than the allowable reverse withstand voltage limit V when the device under test is a polarized capacitor. lim .

[0142] S242: Based on the impedance angle θ1, determine the type of the device under test. If the type of the device under test is a resistor or an inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S243.

[0143] The type is determined based on the effect of the AC signal level on the impedance angle of the device under test.

[0144] If θ1≈0°, the device under test is a resistor; if θ1≈+90°, the device under test is an inductor; if θ1≈-90°, the device under test is a capacitor.

[0145] S243: Apply a second test signal, which includes a first DC bias voltage V1 and a first AC signal, and calculate the loss factor D1 of the device under test.

[0146] Where V1 > 0, V1 > V1p', and V1 + V1p' < V lim .

[0147] In some embodiments of this application, V1 is selected as 50mV.

[0148] After applying V1=50mV and V1'@f11=10mV@1kHz, the LCR meter can measure the loss factor D1 of the output device under test.

[0149] S244: Apply a third test signal, which includes a second DC bias voltage -V1 and a first AC signal, and calculate the loss factor D2 of the device under test.

[0150] When a second DC bias voltage of -50mV is applied, V1'@f 11 After setting the voltage to 10mV@1kHz, the LCR meter can measure the loss factor D2 of the output device under test.

[0151] S245: Based on the loss factors D2 and D3, determine whether the device under test is a non-polarized capacitor, a polarized capacitor connected in the correct direction, or a reversed connection. If the device under test is a non-polarized capacitor or a polarized capacitor connected in the correct direction, proceed to S3. If it is a reversed connection, the LCR meter will output a reversed connection prompt and stop the test.

[0152] Based on the principle of determining the type of non-polarized and polarized capacitors, the connection direction of the identified capacitor can be determined using the following conditions.

[0153] If D1≈D2, it is determined to be a non-polarized capacitor; if D1<D2, it is determined to be a polarized capacitor connected in the correct direction; if D1>D2, it is determined to be a polarized capacitor connected in reverse.

[0154] The reverse connection judgment of S243 and S244 is made by directly applying forward and reverse DC bias voltages and comparing the forward and reverse losses, which is the most intuitive criterion.

[0155] Figure 6 A flowchart illustrating a fifth embodiment of the identification process is shown, in conjunction with... Figure 1 The specific description is as follows.

[0156] S251: Apply a first test signal, the first test signal including a first DC bias voltage V11, a first AC signal level V1', and a first test frequency f. 11 The first AC signal is used to calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1, and loss factor D1 of the device under test.

[0157] In some embodiments of this application, when V11 is applied, 10mV is selected, and V1'@f 11 After setting the value to 10mV@1kHz, the LCR meter can measure the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1, and loss factor D1 of the device under test.

[0158] S252: Apply a second test signal, which includes a second DC bias voltage V21 and a first AC signal, and calculate the impedance amplitude |Z2| and impedance angle θ2 of the device under test.

[0159] As mentioned above, V21 = V11 + ΔV, and ΔV is chosen to be 40mV. Therefore, V21 is 50mV, and V21 + V1p' < V lim .

[0160] In some embodiments of this application, after applying V21 of 50mV and V1'@f1 of 10mV@1kHz, the LCR meter is able to measure the impedance amplitude |Z2| and impedance angle θ2 of the output device under test.

[0161] S253: Based on the impedance amplitudes |Z1|, |Z2|, and impedance angles θ1, θ2, determine the type of the device under test and whether there is a polarized capacitor reversed. If the type of the device under test is a resistor or inductor, proceed to S3. If there is a reverse connection, the LCR meter will output a reverse connection prompt and stop the test. If the type of the device under test is a capacitor and it is connected in the correct direction, proceed to S254.

[0162] As described in S215, the relationship between the R / L / C devices and the frequency and DC bias voltage can be used to determine the type of the device under test using the following conditions.

[0163] If |Z2|≈|Z1| and θ1≈θ2≈0°, the device under test is a resistor; if |Z2|≈|Z1| and θ1≈θ2≈+90°, the device under test is an inductor; if |Z2|=|Z1| and θ1≈θ2≈-90°, the device under test is a capacitor and is connected in the correct orientation; if |Z2| is significantly less than |Z1| and θ2 deviates abnormally towards 0°, it indicates a reverse connection, and the LCR meter will output a reverse connection warning and stop the test.

[0164] S254: Apply a third test signal, the third test signal including a first DC bias voltage V11 and a voltage having V1' and f 11 The third AC signal of / k4 is used to calculate the impedance amplitude |Z3|, impedance angle θ3, equivalent series resistance ESR3, and loss factor D3 of the device under test.

[0165] The choice of k4 is similar to the choice of k1 as described above, and will not be repeated here. Here, k4 is chosen as 10.

[0166] In some embodiments of this application, when V11 is applied at 10mV, V1'@f 11 After setting / k4 to 10mV@100Hz, the LCR meter can measure the impedance amplitude |Z3|, impedance angle θ3, equivalent series resistance ESR3, and loss factor D3 of the device under test.

[0167] S255: Based on the equivalent series resistances ESR3 and ESR1, and the loss factors D3 and D1, determine whether the positively connected capacitor is a non-polarized capacitor or a polarized capacitor, and then proceed to S3.

[0168] Referring to the principle for determining the type of non-polarized and polarized capacitors in S216, the connection direction of the identified capacitor can be determined using the following conditions.

[0169] If ESR1≈ESR3 and D1<0.01, it is judged as a non-polarized capacitor; if the difference between ESR1 and ESR3 is large (for example, a threshold can be set, |ESR1-ESR3|> the set threshold is considered large), and D1≥D3≥0.01, it is judged as a polarized capacitor. The reason is that if it is a polarized capacitor, the test frequency f... 11 D1 relative test frequency f 11 D3 is higher under / k4 and is greater than 0.01 in all cases.

[0170] The identification of the type of device under test (DUT) in S2 mentioned above in this application relies on the inherent physical characteristics of different types of DUTs. It can identify the type of DUT based on evidence. It is driven by the physical laws of the inherent characteristics of the device and has strong universality. When identifying reverse polarity of capacitors, there is no need to set absolute thresholds for different models or capacities of capacitors, avoiding the risk of misjudgment caused by empirical thresholds. When a reverse polarity capacitor is identified, the LCR meter outputs a reverse polarity prompt. When the output prompts a reverse polarity, the test is stopped immediately to avoid continuously applying negative voltage to the polarity capacitor.

[0171] Only after the type of the device under test is identified will the process proceed to S3. Therefore, refer back to [link to previous step]. Figure 7 The description is as follows.

[0172] S3: Determine the measurement range based on the identified type of the device under test.

[0173] After determining the type of the device under test in S2 above, the impedance amplitude |Z| of the device under test can be obtained by testing. Since each measurement range corresponds to an impedance amplitude measurement range, the measurement range that matches the impedance amplitude |Z| can be determined based on the impedance amplitude |Z|.

[0174] In some embodiments of this application, the measurement range can be selected based on experience as being slightly larger than the impedance amplitude |Z|.

[0175] S4: Based on the type of device under test and its measurement range, determine the test frequency f0 and the equivalent circuit model using the industry standard built into the LCR meter.

[0176] The LCR meter incorporates industry standards (IEC 60384 series, GB / T2693, etc.), which means that the test conditions for various devices specified by international and domestic standards such as IEC and GB (including test frequency, equivalent circuit model, DC voltage bias, etc.), the optimal measurement range for accuracy, and the output impedance matching rules (for example, if the impedance amplitude is high (e.g., greater than 1kΩ), then match a high output impedance; if the impedance amplitude is low (e.g., less than 1kΩ), then match a low output impedance). These standards can be solidified into a structured parameter library that can be called within the LCR meter.

[0177] After obtaining the type, connection direction, and measurement range of the device under test, the LCR meter directly retrieves and automatically loads the corresponding test parameters based on these standards, without requiring any professional judgment or manual input from the user. It also ensures that the measurement conforms to industry standards and that the results are authoritative and comparable.

[0178] In some embodiments of this application, after determining the type of the device under test and its measurement range, the test frequency f0 and the equivalent circuit model are determined according to the industry standard built into the LCR meter.

[0179] For example, when the capacitance of a polarized capacitor (e.g., aluminum electrolytic capacitor) is greater than 10μF, the final test frequency f0 is forcibly set to 100Hz or 120Hz to match the equivalent series model (Cs). This frequency f0 is determined according to the nominal capacitance verification frequency of aluminum electrolytic capacitors specified in the IEC standard, which avoids falsely low capacitance caused by parasitic inductance at high frequencies.

[0180] When the capacitance of the polarized capacitor (e.g., tantalum electrolytic capacitor) is less than or equal to 10 μF, f0 is set to 1 kHz, matching the equivalent series model (Cs), which conforms to the IEC 60384-3 standard.

[0181] When the capacitance of the non-polarized capacitor is less than 1nF, f0 is set to 100kHz or 1MHz to match the equivalent parallel model (Cp); when the capacitance is between 1nF and 100nF, f0 is set to 10kHz to match the equivalent parallel model; when the capacitance is between 100nF and 1μF, f0 is set to 10kHz or 1kHz to match the equivalent series model (Cs).

[0182] When the inductance is less than 1mH, f0 is set to 100kHz to match the equivalent series model (Ls); when the inductance is between 1mH and 1H, f0 is set to 1kHz to match the equivalent series model; when the inductance is greater than 1H, f0 is set to 100 Hz to match the equivalent parallel model (Lp).

[0183] When the resistance is less than 10kΩ, f0 is set to 1kHz or DCR (Direct Current Resistance) mode; when the resistance is greater than or equal to 10kΩ, f0 is set to 100Hz.

[0184] S5: Determine the DC bias voltage V0 for testing based on the type of device under test.

[0185] In some embodiments of this application, the corresponding DC bias voltage is different when the device under test is a resistor, inductor, or capacitor.

[0186] When the device under test is a resistor, inductor, or a non-polarized capacitor that is not affected by DC voltage (e.g., thin film, Class I ceramic capacitor), V0=0.

[0187] When the device under test is a non-polarized capacitor that is sensitive to DC electric field (e.g., a Class II ceramic capacitor (X7R, X5R, etc.)), V0 is selected from the user-preset DC bias voltage or the default DC bias voltage of the LCR meter to simulate its DC operating point in the actual circuit and obtain the true effective capacitance.

[0188] When the device under test is a polarized capacitor, V0 is greater than the peak value V0p' corresponding to the AC signal level V0', and the sum of the two is less than the rated voltage V of the device under test. rated .

[0189] Therefore, the choice of V0 needs to balance V0', V0p', and V rated .

[0190] S6: Determine the AC signal level V0' for testing.

[0191] The corresponding AC signal levels differ when the device under test is a resistor, inductor, or capacitor. This is especially true for polarized capacitors.

[0192] When the device under test is a resistor or inductor, V0' can be selected from the user-preset AC signal level or the default AC signal level of the LCR meter.

[0193] As described in S5 above, when the device under test is a polarized capacitor, the selection of V0 needs to balance V0', V0p', and V rated Therefore, V0 and V0' can be combined to determine the value.

[0194] When the device under test is a polarized capacitor, V0 and V0' satisfy the following conditions: V0 > V0p' and V0 + V0p' < V rated .

[0195] In some embodiments of this application, V0 = 0.5V or according to the rated voltage V rated The setting is 1% to 10%, but the above-mentioned conditions must be met to ensure that even after the AC signal level is increased, the instantaneous voltage across the device under test remains positive.

[0196] V0' should be set to the standard recommended value, such as 0.3Vrms to 0.5Vrms, while ensuring the signal-to-noise ratio, but the following limitations must still be met.

[0197] S7: Obtain the impedance amplitude |Z| of the device under test based on V0 and an AC signal with V0' and test frequency f0.

[0198] After initially determining the test frequency f0 (in S4), the DC bias voltage V0 (in S5), and the AC signal level V0' (in S6), the measurement is not performed directly. Instead, a verification test is conducted to calibrate the measurement range. This is because the device impedance amplitude estimated in S3 was performed at a non-standard frequency, and its estimate may deviate from the actual impedance at the standard test frequency f0. Therefore, after determining the test frequency f0, V0, and V0', the true impedance amplitude |Z| is obtained, and the measurement range is accurately set based on this to avoid range overload or insufficient accuracy due to theoretical estimation deviation.

[0199] S8: Determine the range setting based on the impedance amplitude |Z|.

[0200] Based on the impedance amplitude |Z|, determine the range of the LCR meter (i.e., the impedance measurement range) and the output impedance.

[0201] Based on the impedance amplitude |Z|, the LCR meter can directly lock the optimal range.

[0202] The principle behind LCR meters' ability to directly lock the measurement range is to ensure that the measured signal falls within 60% to 90% of the full-scale range of the LCR meter's analog-to-digital converter. This avoids both excessively large ranges, which increase quantization noise and decrease measurement accuracy, and excessively small ranges, which cause signal clipping distortion. The measured range values ​​obtained after verification testing are used instead of theoretical estimates to calibrate the measurement range and ensure accurate and reliable range selection.

[0203] S9: Based on the impedance magnitude |Z|, the LCR meter switches to low output impedance mode or remains in high output impedance mode.

[0204] In some embodiments of this application, a preset impedance amplitude threshold can be set for the impedance amplitude. This preset impedance amplitude threshold can be a range or a specific value, such as |Z|. t .

[0205] When the impedance amplitude |Z| reaches the upper limit of the preset impedance amplitude threshold (e.g., |Z| > |Z|), t or |Z|≥|Z| t When the output impedance is high, the LCR meter maintains its current high output impedance mode, making the output impedance of the LCR meter high output impedance.

[0206] When the impedance amplitude |Z| reaches the lower limit of the preset impedance amplitude threshold (e.g., |Z| < |Z|), t Or |Z|≤|Z| t When the output impedance is low, the LCR meter will switch from the current high output impedance mode to the low output impedance mode, making the output impedance of the LCR meter low.

[0207] S9': Determine whether the measured signal deviates from the matched dynamic range. If yes, fine-tune the AC signal level V0' for testing and return to S7. If no, end.

[0208] To ensure accurate test results, the measured signal needs to fall within the matching dynamic range. When the measured signal falls within this dynamic range, the quantization error is small, the signal-to-noise ratio is high, and the measurement accuracy is high. If it does not fall within this dynamic range, consider adjusting the AC signal level. This is because the AC signal level is the detection excitation applied to the device under test by the LCR meter, which directly determines the strength of the measured signal. When the measured signal exceeds the appropriate dynamic range, consider adjusting the AC signal level first.

[0209] A low AC signal level will result in insufficient signal-to-noise ratio and large fluctuations in measured values; a high AC signal level will cause the device under test to enter the nonlinear region or even be damaged.

[0210] Therefore, depending on whether the measured signal deviates from the matched dynamic range, the AC signal level V0' of the test is finely adjusted (i.e., increased or decreased) so that the measured signal falls within the matched dynamic range.

[0211] When the impedance amplitude of the device under test is too high and the signal-to-noise ratio is insufficient, the AC signal level needs to be increased. When the impedance amplitude of the device under test is too low, close to overload or signal distortion, the AC signal level needs to be decreased.

[0212] In some embodiments of this application, the amplitude of the AC signal level fine-tuning can be preset.

[0213] It should be noted that when the device under test is a polarized capacitor, during the adjustment process, it is necessary to ensure that V0 > V0p' and V0 + V0p' < V rated .

[0214] As mentioned above, the matching dynamic range can refer to the range that meets the measurement accuracy of the LCR meter itself, or the range corresponding to 60% to 90% of the full scale of the analog-to-digital converter within the LCR meter.

[0215] After fine-tuning the AC signal level, return to S7 and reconfirm the range setting and impedance output mode until the measured signal falls within the matched dynamic range. At this point, the LCR meter's test parameters are set.

[0216] As described in S7 to S9' above, by utilizing the type of the device under test (DUT) and the standard measurement frequency, the AC signal level can be finely adjusted to achieve coordinated optimization of the measurement range and output impedance, determining the optimal range so that the measured signal always falls within the optimal dynamic range of the analog-to-digital converter (e.g., 60% to 90% of full scale). Simultaneously, the output impedance is switched to a mode that matches the output impedance of the DUT, achieving optimal source-load matching. This coordinated optimization of the measurement range and output impedance maximizes the signal-to-noise ratio and accuracy of the final measurement.

[0217] In some embodiments of this application, see Figure 7 This application also relates to an LCR meter testing method, which enables the LCR meter to meet the measurement requirements of the device under test.

[0218] See ​ The LCR table testing methods include S100 and S200.

[0219] Before the actual measurement, the test parameters of the LCR meter for the device under test are determined using the LCR meter test parameter setting method described above (S100). That is, after finally determining the test frequency f0, DC voltage bias V0, range, output impedance (corresponding output impedance mode), AC signal level V0' and equivalent circuit model, a test signal is applied to the device under test (S200) to enter the final measurement stage, complete the full parameter measurement of the device under test, obtain the main parameters (e.g., R / L / C values, impedance amplitude, impedance angle, etc.) and complex parameters (loss factor D, quality factor Q, etc.), and display them on the LCR meter.

[0220] The LCR meter testing method involved in this application only requires two actions from the user's perspective: "clamping the device under test" and "pressing the start measurement button." All complex judgments, settings, and optimizations are completed within the LCR meter, achieving "one-click" safe, standardized, and accurate measurement. It does not depend on the user's professional level, enabling non-professionals to obtain professional-level measurement results.

[0221] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A method for setting test parameters of an impedance testing device, characterized in that, include: S1: Set the output impedance mode of the impedance testing equipment to high output impedance mode, and set its measurement range to automatic mode or the highest range. S2: Based on the characteristics of different types of devices under test, different test signals are applied to identify the type of device under test. When a polarized capacitor is detected to be reverse-connected, the impedance test device outputs a reverse connection prompt and stops the test. The test signal includes a DC bias voltage V and an AC signal with an AC signal level V' and a test frequency f. The sum of the peak values ​​Vp corresponding to V and the AC signal level V' is less than the allowable reverse withstand voltage limit V of the device under test when it is a polarized capacitor. lim And when V > 0, V > Vp; S3: Determine the measurement range based on the identified type of the device under test; S4: Based on the type of the device under test and its measurement range, determine the test frequency f0 and the equivalent circuit model using the industry standard built into the impedance testing equipment; S5: Determine the DC bias voltage V0 for testing based on the type of device under test; S6: Determine the AC signal level V0' for testing. When the device under test is a polarized capacitor, V0 is greater than the peak value V0p' corresponding to V0', and the sum of the two is less than the rated voltage V of the device under test. rated ; S7: Obtain the impedance amplitude of the device under test based on V0 and an AC signal with test AC signal level V0' and test frequency f0; S8: Determine the range setting based on the impedance amplitude; S9: Based on the impedance amplitude, the impedance testing equipment switches to a low output impedance mode or maintains a high output impedance mode; S9': Determine whether the measured signal deviates from the matched dynamic range. If yes, fine-tune the AC signal level V0' used for testing and return to S7. If no, end. Wherein, when the device under test is a polarized capacitor, V0 is greater than the peak value V0p' corresponding to the fine-tuned AC signal level V0', and the sum of the two is less than the rated voltage V of the device under test. rated .

2. The method for setting test parameters of the impedance testing equipment according to claim 1, characterized in that, S2 include: S211: Apply a first test signal, the first test signal including a first DC bias voltage V1 and a first AC signal having a first AC signal level V1' and a first test frequency f1, and calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test, wherein V1 > 0 and is greater than the peak value V1p' corresponding to the first AC signal level V1'; S212: Apply a second test signal, the second test signal including a second DC bias voltage V2 and the first AC signal, and calculate the impedance amplitude |Z2| and impedance angle θ2 of the device under test, where V2=V1+ΔV, ΔV is a preset increment greater than zero, and the sum of V2 and V1p' is less than the reverse withstand voltage limit allowed when the device under test is a polarized capacitor; S213: Based on the impedance amplitudes |Z1|, |Z2| and impedance angles θ1, θ2, determine whether there is a polarized capacitor reversed. If yes, the impedance test equipment outputs a reverse connection prompt and stops the test. If no, proceed to S214. S214: Apply a third test signal, which includes V1 and a second AC signal having V1' and k1*f1, and calculate the impedance amplitude |Z3|, impedance angle θ3, equivalent series resistance ESR3 and loss factor D3 of the device under test, where k1 is a preset coefficient greater than 1. S215: Based on the impedance amplitudes |Z1|, |Z2|, |Z3|, impedance angles θ1, θ2, θ3 and k1, determine the type of the device under test. If the type of the device under test is a resistor or an inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S216. S216: Based on the equivalent series resistances ESR1 and ESR3 and the loss factors D1 and D3, determine whether the device under test is a non-polarized capacitor or a positively connected polarized capacitor, and then proceed to S3.

3. The method for setting test parameters of the impedance testing equipment according to claim 1, characterized in that, S2 includes: S221: Apply a first test signal, the first test signal including a first DC bias voltage V1 and a first AC signal having a first AC signal level V1' and a first test frequency f1, and calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test, wherein V1 > 0 and is greater than the peak value V1p' corresponding to the first AC signal level V1'; S222: Apply a second test signal, which includes a second DC bias voltage V2 and a second AC signal with V1' and k2*f1, and calculate the impedance amplitude |Z2|, impedance angle θ2 and equivalent series resistance ESR2 of the device under test, where V2=V1+ΔV, ΔV is a preset increment greater than zero, k2 is a preset coefficient greater than 1, and the sum of V2 and V1p' is less than the reverse withstand voltage limit allowed when the device under test is a polarized capacitor; S223: Based on the impedance amplitudes |Z1|, |Z2|, impedance angles θ1, θ2 and k2, determine the type of the device under test and whether there is a polarized capacitor reversed. If the type of the device under test is a resistor or an inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S224. If there is a reverse connection, the impedance test equipment outputs a reverse connection prompt and stops the test. S224: Based on the equivalent series resistances ESR1 and ESR2 and the loss factor D1, determine whether the device under test is a non-polarized capacitor or a positively connected polarized capacitor, and then proceed to S3.

4. The method for setting test parameters of the impedance testing equipment according to claim 1, characterized in that, S2 includes: S231: Apply a first test signal, the first test signal including a first DC bias voltage V1 and a first AC signal having a first AC signal level V1' and a first test frequency f1, and calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test, wherein V1 > 0, V1 is greater than the peak value V1p' corresponding to the first AC signal level V1', and the sum of V1 and V1p' is less than the reverse withstand voltage limit allowed when the device under test is a polarized capacitor; S232: Apply a second test signal, the second test signal including the first DC bias voltage V1 and a second AC signal having V1' and k3*f1, and calculate the impedance amplitude |Z2|, equivalent series resistance ESR2 and loss factor D2 of the device under test, where k3 is a preset coefficient greater than 1; S233: Based on the impedance amplitudes |Z1|, |Z2|, impedance angles θ1, k2, and equivalent series resistances ESR1 and ESR2, determine the type of the device under test and whether there is a polarized capacitor reversed. If the type of the device under test is a resistor or inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S224. If there is a reverse connection, the impedance test equipment outputs a reverse connection prompt and stops the test. S234: Based on the equivalent series resistances ESR1 and ESR2 and the loss factor D1, determine whether the device under test is a non-polarized capacitor or a positively connected polarized capacitor, and then proceed to S3.

5. The method for setting test parameters of the impedance testing equipment according to claim 1, characterized in that, S2 include: S241: Apply a first test signal, the first test signal including a first AC signal level V1' and a first test frequency f. 11 The first AC signal is used to calculate the impedance angle θ1 of the device under test, where the peak value V1p' corresponding to the first AC signal level V1' is less than the allowable reverse withstand voltage limit V when the device under test is a polarized capacitor. lim ; S242: Based on the impedance angle θ1, determine the type of the device under test. If the type of the device under test is a resistor or an inductor, proceed to S3. If the type of the device under test is a capacitor, proceed to S243. S243: Apply a second test signal, the second test signal including a first DC bias voltage V1 and the first AC signal, and calculate the loss factor D1 of the device under test, wherein V1 > 0, V1 > V1p', and V1 + V1p' < V lim ; S244: Apply a third test signal, the third test signal including a second DC bias voltage -V1 and the first AC signal, and calculate the loss factor D2 of the device under test; S245: Based on the loss factors D1 and D2, determine whether the device under test is a non-polarized capacitor, a positively connected polarized capacitor, or a reverse-connected capacitor. If the device under test is a non-polarized capacitor or a positively connected polarized capacitor, proceed to S3. If it is a reverse-connected capacitor, the impedance testing equipment outputs a reverse connection prompt and stops the test.

6. The method for setting test parameters of the impedance testing equipment according to claim 1, characterized in that, S2 include: S251: Apply a first test signal, the first test signal including a first DC bias voltage V11 and having a first AC signal level V1' and a first test frequency f. 11 The first AC signal is used to calculate the impedance amplitude |Z1|, impedance angle θ1, equivalent series resistance ESR1 and loss factor D1 of the device under test, where V11 > 0 and V11 is greater than the peak value V1p' corresponding to the first AC signal level V1'. S252: Apply a second test signal, which includes a second DC bias voltage V21 and the first AC signal, and calculate the impedance amplitude |Z2| and impedance angle θ2 of the device under test, where V21 = V11 + ΔV, ΔV is a preset increment greater than zero, and the sum of V21 and V1p' is less than the allowable reverse withstand voltage limit V when the device under test is a polarized capacitor. lim ; S253: Based on the impedance amplitudes |Z1|, |Z2|, and impedance angles θ1, θ2, determine the type of the device under test and whether there is a polarized capacitor reversed. If the type of the device under test is a resistor or an inductor, proceed to S3. If there is a reverse connection, the impedance test equipment outputs a reverse connection prompt and stops the test. If the type of the device under test is a capacitor and it is connected in the correct direction, proceed to S254. S254: Apply a third test signal, the third test signal including the first DC bias voltage V11 and having V1' and f 11 The second AC signal of / k4 is used to calculate the impedance amplitude |Z3|, impedance angle θ3, equivalent series resistance ESR3 and loss factor D3 of the device under test, where k4 is a preset coefficient greater than 1. S255: Based on the equivalent series resistances ESR3 and ESR1, and the loss factors D3 and D1, determine whether the positively connected capacitor is a non-polarized capacitor or a polarized capacitor, and proceed to S3.

7. The method for setting test parameters of the impedance testing equipment according to any one of claims 1 to 6, characterized in that, In S5, the DC bias voltage V0 for testing is determined according to the type of the device under test, specifically as follows: When the device under test is a resistor, inductor, or a non-polarized capacitor unaffected by DC voltage, V0 = 0; When the device under test is a non-polarized capacitor that is sensitive to DC electric field, V0 is selected as the user-preset DC bias voltage or the default DC bias voltage of the impedance test equipment. When the device under test is a polarized capacitor, V0 is chosen to be greater than V0p' and the sum of the two is less than V. rated The value of .

8. The method for setting test parameters of the impedance testing equipment according to claim 1, characterized in that, S9 specifically refers to: When the impedance amplitude reaches the upper limit of the preset impedance amplitude threshold, the impedance testing device maintains the current high output impedance mode, so that the output impedance of the impedance testing device is a high output impedance. When the impedance amplitude reaches the lower limit of the preset impedance amplitude threshold, the impedance testing device switches the current high output impedance mode to low output impedance mode, so that the output impedance of the impedance testing device is low output impedance.

9. The method for setting test parameters of the impedance testing equipment according to claim 1, characterized in that, In S9', the test AC signal level V0' is finely adjusted, specifically as follows: Increase or decrease the AC signal level V0' used for testing so that the signal under test falls within the matched dynamic range, wherein the matched dynamic range refers to the range corresponding to 60% to 90% of the full scale of the analog-to-digital converter in the impedance testing equipment.

10. An impedance testing device and testing method for testing devices, characterized in that, The impedance testing equipment testing method includes: The test parameters of the impedance testing equipment for the device under test are determined using the impedance testing equipment test parameter setting method as described in any one of claims 1 to 9; Using the determined test parameters, a test signal is applied to the device under test, and the test results are displayed on the impedance testing equipment.

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