A method and system for supercapacitor measurement

Abstract

This application discloses a supercapacitor measurement method and system, relating to the field of supercapacitor testing technology. The method employs segmented discharge combined with dynamic threshold determination. First, a large current is rapidly passed through the nonlinear region. Then, the effective measurement range is adjusted in real time based on temperature, discharge current, and internal resistance. Finally, a small current is switched to complete high-precision sampling. Therefore, this method solves the technical problems of traditional measurement methods, such as susceptibility to operating condition fluctuations, inaccurate linear region determination, large nonlinear region errors, and poor measurement consistency. It achieves high measurement accuracy, strong adaptability, stable and reliable results, and faster detection speed.

Description

Technical Field

[0001] This application relates to the field of supercapacitor testing technology, and in particular to a supercapacitor measurement method and system. Background Technology

[0002] During the constant current discharge process of a supercapacitor, its discharge voltage curve includes two nonlinear regions: a voltage drop region at the beginning of the discharge caused by the equivalent series resistance, and a nonlinear decay region at the end of the discharge caused by the diffusion effect. Only in the middle section does the voltage exhibit an approximately linear decrease.

[0003] There are two main methods for measuring capacitance values ​​in existing technologies: the first is the fixed voltage range method, which involves measuring within a preset voltage range. However, the fixed range may contain nonlinear regions and cannot adapt to changes in conditions such as temperature, aging, and discharge current, thus introducing significant measurement errors. The second method is the time-delay start measurement method, which involves waiting for a fixed delay after discharge before starting the measurement. The problem with this method is that the delay parameter is fixed, making it difficult to match the actual characteristics under different capacitance states.

[0004] In summary, existing technologies cannot dynamically identify the true linear region of the supercapacitor discharge curve, resulting in systematic errors in capacitance measurement and making it difficult to meet the requirements of high-precision and highly adaptable application scenarios. Summary of the Invention

[0005] This application provides a supercapacitor measurement method and system to at least solve the problem in related technologies that the true linear region of the supercapacitor discharge curve cannot be dynamically identified.

[0006] This application provides a method for measuring supercapacitors, including: Discharge the supercapacitor pack according to the first discharge current; The starting and ending voltages of the linear region are dynamically calculated based on the real-time temperature, current discharge current, and equivalent series resistance of the supercapacitor pack. After determining that the supercapacitor pack has entered the linear discharge region, the supercapacitor pack is discharged according to the second discharge current, which is less than the first discharge current. The capacitance value is measured within the range of voltage drop from the initial voltage to the final voltage of the supercapacitor pack.

[0007] This application also provides a supercapacitor measurement system for implementing any of the above-described supercapacitor measurement methods. The system includes: a first constant current circuit, a second constant current circuit, a current switching circuit, and a main controller. The first terminal of the current switching circuit is connected to the supercapacitor pack, and the second terminal of the current switching circuit is connected to the first terminal of the first constant current circuit and the first terminal of the second constant current circuit respectively. The control terminal of the current switching circuit is connected to the first output terminal of the main controller. The current switching circuit is used to receive the switching signal sent by the main controller, and in response to the first switching signal, it conducts the path from the first constant current circuit to the supercapacitor pack, and in response to the second switching signal, it conducts the path from the second constant current circuit to the supercapacitor pack. The discharge current of the second constant current circuit is less than the discharge current of the first constant current circuit. The main controller's acquisition terminal is connected to the supercapacitor pack. The main controller is used to dynamically calculate the start and end voltages of the linear region based on the real-time temperature, current discharge current, and equivalent series resistance of the supercapacitor pack. During the initial discharge phase, the main controller sends a first switching signal to the current switching circuit. After determining that the supercapacitor pack has entered the linear discharge region, it sends a second switching signal and calculates the capacitance value within the linear discharge region.

[0008] By employing segmented discharge combined with dynamic threshold determination, this application first rapidly passes through the nonlinear region with a large current, then adjusts the effective measurement range in real time based on temperature, discharge current, and internal resistance, and switches to a small current to complete high-precision sampling. Therefore, it can solve the technical problems of traditional measurement methods, such as susceptibility to operating condition fluctuations, inaccurate determination of the linear region, large errors in the nonlinear region, and poor measurement consistency. This achieves the technical effects of high measurement accuracy, strong adaptability, stable and reliable results, and faster detection speed. Attached Figure Description

[0009] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0010] Figure 1 This is a schematic diagram of the discharge process of a supercapacitor pack. Figure 2 A schematic flowchart illustrating the supercapacitor measurement method provided in the embodiments of this application; Figure 3 This is a schematic diagram of the capacitance measurement threshold provided in an embodiment of this application; Figure 4 This is a schematic diagram of the supercapacitor measurement system provided in an embodiment of this application; Figure 5 This is another schematic flowchart of a supercapacitor measurement method provided in an embodiment of this application. Detailed Implementation

[0011] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0012] It should be noted that, in the description of this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. The terms "first," "second," etc., in this application are used to distinguish similar objects and are not used to describe a specific order or sequence.

[0013] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0014] like Figure 1 As shown, the supercapacitor starts discharging from point A during constant current discharge. In the section from A to C, the capacitor voltage drops rapidly due to the influence of the equivalent series resistance, forming a nonlinear discharge region. After the voltage drops to point C, the discharge curve enters the linear discharge region. Therefore, the accurate calculation of the capacitance value needs to be carried out within the linear interval from C to D.

[0015] Currently, the commonly used methods for measuring the capacitance of supercapacitors are mainly divided into the fixed voltage range method and the delayed start measurement method. Both methods have obvious limitations and measurement errors.

[0016] The fixed voltage range method measures capacitance within a preset voltage range (e.g., 2.7V~10.8V), assuming this range to be the linear discharge range. This method is prone to measurement errors due to the inclusion of a nonlinear region (A→C) within the fixed voltage range. Increased equivalent series resistance at low temperatures extends this nonlinear region, but the fixed range cannot be dynamically adjusted accordingly. Furthermore, high-current discharge further expands the nonlinear region, resulting in measurement errors as high as 25%.

[0017] The delayed-start measurement method involves delaying the constant current discharge for a fixed duration T_delay (typically 5-30 seconds) before collecting voltage data and calculating the capacitance. This method, with its fixed delay parameter, cannot accommodate changes in ESR (Equivalent Series Resistance) caused by capacitor aging. New capacitors will experience reduced measurement efficiency due to excessive delay, while aged capacitors will remain in the nonlinear region due to insufficient delay. Furthermore, the stabilization time of the equivalent series resistance varies significantly under different temperatures, and the delay requirement changes nonlinearly with changes in discharge current. A fixed delay is difficult to match actual operating conditions. Moreover, this method does not avoid the nonlinear decay region after point D at the end of the discharge, still introducing calculation errors.

[0018] In summary, traditional measurement methods cannot dynamically identify and lock the true linear interval in the discharge curve of a supercapacitor, resulting in systematic errors in capacitance measurement and making it difficult to meet the needs of high-precision measurement scenarios.

[0019] Therefore, embodiments of this application provide a supercapacitor measurement method, and the method is described in detail below in conjunction with the execution flow of the supercapacitor measurement method. Figure 2 As shown, the process includes the following steps: Step S1: Discharge the supercapacitor pack according to the first discharge current.

[0020] Specifically, after the supercapacitor pack completes charging and reaches full charge, the discharge process is initiated. The supercapacitor pack is controlled to undergo constant current discharge with a relatively large initial discharge current. The main purpose of this stage is to enable the supercapacitor pack to quickly pass through the initial nonlinear region where the voltage drops sharply due to the equivalent series resistance, thereby shortening the overall measurement time and improving detection efficiency. In this embodiment, the supercapacitor pack is an energy storage module composed of multiple supercapacitor cells connected in series and / or parallel, used to provide a stable discharge voltage and energy storage capacity.

[0021] Step S2: Based on the real-time temperature of the supercapacitor pack, the current discharge current, and the equivalent series resistance, dynamically calculate the starting and ending voltages of the linear region.

[0022] Specifically, the system acquires the operating temperature of the supercapacitor pack in real time and obtains the current discharge current. Combined with pre-stored or real-time detected equivalent series resistance parameters, and based on a temperature compensation model and an adaptive operating condition algorithm, it calculates and updates the start and end voltages of the linear discharge region in real time. The start voltage identifies the end point of the nonlinear region, and the end voltage identifies the start point of the discharge terminal diffusion effect. Dynamic calculations allow the measurement range to adapt to different operating conditions such as temperature changes, capacitor aging, and discharge current fluctuations.

[0023] Step S3: After determining that the supercapacitor pack has entered the linear discharge region, the supercapacitor pack is discharged according to the second discharge current, which is less than the first discharge current.

[0024] Specifically, the voltage and voltage change rate of the supercapacitor pack are continuously monitored. When the voltage reaches the dynamically calculated starting voltage and the voltage change rate meets the linear discharge judgment condition, the supercapacitor pack is confirmed to have entered the stable linear discharge region. At this time, a smaller second discharge current is used to continue constant current discharge of the supercapacitor pack, making the voltage change more gradual and stable, thus providing a basis for subsequent high-precision capacitance measurement.

[0025] Step S4: Capacitance measurement is performed within the range where the voltage of the supercapacitor pack drops from the initial voltage to the final voltage.

[0026] Specifically, within the entire linear range of the supercapacitor pack's voltage drop from the initial voltage to the final voltage, the system records the discharge start and end times, along with the corresponding voltage changes. Combined with the constant value of the second discharge current, the precise capacitance value of the supercapacitor pack is obtained using the capacitance calculation formula. This measurement range completely avoids the initial nonlinear drop region and the final nonlinear decay region, thus significantly improving the accuracy and reliability of the measurement results.

[0027] The embodiments of this application provide a supercapacitor measurement method that, by employing dynamic threshold calculation combined with voltage change rate composite judgment, can adapt to changes in operating conditions such as temperature, aging, and discharge current, accurately identifying a stable linear discharge range unaffected by ESR and diffusion effects. Simultaneously, it utilizes dual-channel constant current segmented discharge to achieve rapid passage through the nonlinear region and high-precision measurement separation control. Therefore, it can solve the technical problems of traditional fixed voltage range and fixed delay methods being unable to adapt to changes in operating conditions, easily introducing nonlinear region errors, and having low measurement accuracy. This achieves the technical effects of stable and accurate measurement results, strong adaptability, fast measurement speed, and wide applicability, significantly improving the operating condition adaptability and dynamic response capability of the measurement system, maintaining stable and accurate measurement performance under different environments and current levels.

[0028] In one alternative implementation, combined with Figure 3 The discharge curves shown define the boundary thresholds of the nonlinear discharge region as V1 and V2. V1 is the starting voltage of the linear region, i.e., the end point of the region affected by the equivalent series resistance; V2 is the ending voltage of the linear region, i.e., the starting point of the diffusion effect region. Due to the combined influence of temperature, discharge current, and changes in equivalent series resistance, V1 and V2 are not fixed values ​​and need to be dynamically calculated based on real-time operating conditions. Accordingly, the formula for calculating the starting voltage V1 of the linear region is as follows: V1 = V_max - I × ESR_T Where V1 is the starting voltage of the linear region, V_max is the initial voltage of the supercapacitor pack, I is the current discharge current, and ESR_T is the equivalent series resistance after temperature compensation.

[0029] Specifically, ESR_T = ESR_25℃ × [1 + k1 × (T - 25)], where ESR_25℃ is the equivalent series resistance of the supercapacitor pack under a standard environment of 25℃, T is the current temperature, and k1 is a proportionality coefficient, the value of which is limited to 0.06 ≤ k1 ≤ 0.10. In this embodiment, the proportionality coefficient k1 is preferably set to 0.08.

[0030] The above calculation method can be used to dynamically adjust the starting voltage by combining changes in real-time temperature, discharge current, and equivalent series resistance. This allows the linear region determination boundary to be adapted to supercapacitor packs with different operating conditions and aging levels, effectively avoiding linear region identification deviations caused by temperature fluctuations or changes in equivalent series resistance.

[0031] The formula for calculating the end voltage V2 of the linear region is as follows: V2=V_min+k2×I×(1+αΔT)+V_offset Where V2 is the end voltage of the linear region, V_min is the cutoff voltage of the supercapacitor pack, k2 is the current influence coefficient, α is the temperature coefficient, ΔT is the temperature change, and V_offset is the safety margin.

[0032] Specifically, k2 is the current influence coefficient, used to characterize the adjustment effect of the discharge current on the termination voltage; in this embodiment, its value is 0.02. α is the temperature coefficient, used to reflect the compensation effect of temperature changes on the termination voltage; in this embodiment, its value is 0.005 / ℃. V_offset is the safety margin, used to prevent the measurement interval from entering the nonlinear region at the end; in this embodiment, its value is 0.1V. ΔT is the temperature change, used to characterize the change between the current temperature and the reference temperature.

[0033] Using the above formula, the system can adaptively determine the termination voltage by combining the cutoff voltage, discharge current, temperature change, and safety margin. This effectively avoids the nonlinear attenuation region caused by the diffusion effect at the end of the discharge, ensuring that the measurement interval falls entirely within the stable linear discharge range, and further improving the accuracy and reliability of capacitance measurement.

[0034] In one alternative implementation, besides dynamically calculating the thresholds V1 and V2 based on capacitor temperature, discharge current, and equivalent series resistance, factors such as temperature changes and capacitor aging can cause the actual linear region starting point V1 to drift. Relying solely on fixed voltage thresholds for determination is insufficient to adapt to boundary shifts caused by changes in operating conditions, easily introducing measurement errors. Therefore, this embodiment introduces a voltage change rate detection mechanism, which can track the dynamically drifting starting position of the linear region in real time.

[0035] The formula for calculating the preset voltage change rate threshold is: dv_threshol / dt=-k1×I×(1+αΔT) By calculating and monitoring the voltage change rate in real time, the inflection point of the discharge voltage transitioning from a rapid drop to a steady decrease can be accurately identified. When the voltage drop rate transitions from a sharp drop in the nonlinear region to a uniform change in the linear region, combined with the current discharge current, it can be accurately confirmed that the supercapacitor has entered the stable linear discharge range, thereby significantly improving the reliability and measurement accuracy of linear region identification.

[0036] Furthermore, the conditions for determining whether a supercapacitor pack has entered the linear discharge region include: the voltage of the supercapacitor pack is less than or equal to the starting voltage, and its voltage change rate is greater than a preset voltage change rate threshold.

[0037] Specifically, the current voltage of the supercapacitor pack is collected in real time, and the voltage change rate per unit time is calculated. The supercapacitor pack is determined to have entered a stable linear discharge region if and only if the following two conditions are met simultaneously: first, the current voltage of the supercapacitor pack is less than or equal to the dynamically calculated starting voltage of the linear region; second, the voltage change rate of the supercapacitor pack is greater than a preset voltage change rate threshold.

[0038] By using the above composite judgment conditions, the end time of the initial nonlinear discharge stage caused by the equivalent series resistance can be accurately identified, avoiding the error caused by relying solely on a single voltage threshold. This ensures that subsequent capacitance measurements are performed within the linear discharge range, thereby improving the accuracy and stability of the measurement results.

[0039] This embodiment also adds a temperature-internal resistance coupling correction compensation mechanism. While collecting temperature and discharge current parameters, it identifies the equivalent series resistance of the supercapacitor pack online and constructs a multi-parameter coupled correction model of temperature, equivalent series resistance, and discharge current to dynamically compensate for the offset of the start and end voltages in the linear region. Unlike the traditional single voltage threshold determination method, this method uses multi-physical quantity coupling adaptive correction to offset the threshold deviation caused by environmental temperature drift, device aging, and internal resistance drift in real time, accurately avoiding the interference of the initial nonlinear region caused by the equivalent series resistance and the end nonlinear region caused by the diffusion effect.

[0040] This embodiment combines dynamic boundary adaptive calculation with segmented discharge measurement to overcome the shortcomings of traditional fixed voltage boundaries that cannot adapt to changes in temperature, aging, and current conditions, thus significantly reducing measurement errors. At the same time, relying on a multi-parameter coupling compensation mechanism, it significantly improves the operating condition adaptability and dynamic response capability of the measurement system, maintaining stable and accurate measurement results under different environments and current levels, and meeting the high-precision and high-consistency capacitance value detection requirements of supercapacitors in industrial scenarios. Embodiments of this application provide a supercapacitor measurement system, such as... Figure 4 As shown, it includes: a first constant current circuit 1, a second constant current circuit 2, a current switching circuit 3, and a main controller 4.

[0041] The first end of the current switching circuit 3 is connected to the supercapacitor pack, and the second end of the current switching circuit 3 is connected to the first end of the first constant current circuit 1 and the first end of the second constant current circuit 2 respectively. The control end of the current switching circuit 3 is connected to the first output end GPIO1 of the main controller 4. The current switching circuit 3 is used to receive the switching signal sent by the main controller 4, and in response to the first switching signal, it conducts the path from the first constant current circuit 1 to the supercapacitor pack, and in response to the second switching signal, it conducts the path from the second constant current circuit 2 to the supercapacitor pack. The discharge current of the second constant current circuit 2 is less than the discharge current of the first constant current circuit 1.

[0042] The main controller 4's acquisition terminals IN1 and IN2 are connected to the supercapacitor pack. The main controller 4 is used to dynamically calculate the starting voltage and ending voltage of the linear region based on the real-time temperature of the supercapacitor pack, the current discharge current, and the equivalent series resistance. In the initial discharge stage, the main controller 4 sends a first switching signal to the current switching circuit 3. After determining that the supercapacitor pack has entered the linear discharge region, it sends a second switching signal and calculates the capacitance value within the linear discharge region.

[0043] Specifically, the supercapacitor pack, as the object under test, has its discharge circuit connected to the first constant current circuit 1 and the second constant current circuit 2 via the current switching circuit 3. The current switching circuit 3 is responsible for switching between the two constant current circuits, and its control terminal is directly driven by the main controller 4 to achieve automatic switching of the discharge mode. In this embodiment of the invention, the main controller 4 is implemented using an MCU (Microcontroller Unit), which has a built-in analog-to-digital converter (ADC) module that can collect the voltage signal across the supercapacitor and the temperature signal of the supercapacitor pack in real time, and complete the analog-to-digital conversion and data processing. The current switching circuit 3 is implemented using a high-speed optocoupler, which has fast switching and electrical isolation characteristics. Its switching time is less than 1ms, which can ensure that the discharge current switches between the two paths without disturbance and with high precision.

[0044] During system operation, the main controller 4 collects real-time operating status information of the supercapacitor pack. Based on the collected temperature, discharge current, and equivalent series resistance, it calculates the suitable linear discharge range for the current supercapacitor pack, obtaining the corresponding start and end voltages. In the initial discharge phase, the main controller 4 controls the current switching circuit 3 to connect the first constant current circuit 1, enabling the supercapacitor pack to discharge rapidly with the first discharge current, quickly moving it out of the initial nonlinear discharge region. Once the main controller 4 determines that the supercapacitor pack has entered a stable linear discharge range, it switches the current switching circuit 3 to the second constant current circuit 2, allowing the supercapacitor pack to maintain a stable discharge with the second discharge current, which is less than the first discharge current.

[0045] Based on this, the main controller 4 collects relevant electrical parameters and completes capacitance calculation during the process of the supercapacitor pack voltage dropping from the starting voltage to the ending voltage in the linear region, thereby achieving high-precision capacitance measurement while avoiding the nonlinear region.

[0046] The supercapacitor measurement in this embodiment of the invention employs an adaptive segmented discharge and linear interval precise measurement strategy, such as... Figure 5 As shown, the entire measurement process is divided into an initial discharge stage, a measurement stage, and a capacitance calculation stage. The specific implementation methods for each stage are as follows: 1) Initial discharge stage After the system starts up, it first enters the initial rapid discharge process. The main controller 4 controls the current switching circuit 3 to conduct the first constant current circuit 1, and discharges the supercapacitor with a large current of 0.2C, so that it can quickly pass through the nonlinear region of rapid voltage drop caused by the equivalent series resistance, and shorten the overall measurement time.

[0047] During this stage, the main controller 4 samples the voltage of the supercapacitor pack in real time using its built-in ADC, continuously calculates the voltage drop rate dv / dt, and combines this with the dynamically calculated linear region initiation voltage V1 for a composite determination. The system determines that the supercapacitor pack has entered the stable linear discharge region if and only if the voltage drop rate dv / dt < -0.1I and the current voltage V < V1.

[0048] 2) Measurement Phase After completing the linear region determination, the main controller 4 immediately drives the current switching circuit 3 to turn off the first constant current circuit 1 and turn on the second constant current circuit 2, quickly switching to a precise small current of 0.05C for discharge.

[0049] The system performs stable measurements within the dynamic voltage range of [V1, V2], continuously collecting voltage and time information until the supercapacitor voltage drops to the linear region termination voltage V2, at which point the measurement process ends.

[0050] 3) Capacity Calculation Stage After the measurement is completed, the main controller 4 calculates the capacitance of the supercapacitor pack based on the collected parameters. The calculation formula is as follows: C = I_measure × (t_end - t_start) / (V1 - V2) In the formula: I_measure is the constant discharge current used in the measurement stage, with a value of 0.05C; t_start is the moment when the voltage enters the linear region starting voltage V1; t_end is the moment when the voltage drops to the linear region ending voltage V2; V1-V2 is the voltage change within the measurement interval.

[0051] Based on the above formula, the system can accurately calculate the actual capacitance value of the supercapacitor pack, effectively avoiding calculation deviations caused by nonlinearity and improving the accuracy and reliability of the measurement results.

[0052] In one alternative implementation, such as Figure 4 As shown, the first constant current circuit 1 includes: a first voltage regulator U1, a first transistor T1, a second transistor T2, and a first resistor R1. The first terminal of the first transistor T1 is connected to the current switching circuit 3. The second terminal of the first transistor T1 is connected to both the first terminal of the first resistor R1 and the reference electrode of the first voltage regulator U1. The control terminal of the first transistor T1 is connected to both the cathode of the first voltage regulator U1 and the DC power supply. The anode of the first voltage regulator U1 is grounded. The first terminal of the second transistor T2 is connected to the second terminal of the first resistor R1. The control terminal of the second transistor T2 is connected to the second output terminal GPIO2 of the main controller 4. The second terminal of the second transistor T2 is grounded.

[0053] Specifically, when the main controller 4 outputs a control signal through the second output terminal GPIO2 to turn on the second transistor T2, the first resistor R1 forms a path to ground, and the first voltage regulator U1 enters the working state. The first voltage regulator U1 stabilizes its reference potential at the reference voltage, thereby driving and adjusting the conduction state of the first transistor T1, so that the first transistor T1 operates in a constant current output state. The first resistor R1 is a current setting resistor, and the magnitude of the discharge current output by the first constant current circuit 1 can be flexibly adjusted by changing its resistance value.

[0054] The first transistor T1 acts as a constant current regulator. Under the closed-loop regulation of the first voltage regulator U1, it maintains a constant discharge current, unaffected by power supply voltage fluctuations, temperature changes, and supercapacitor voltage variations, ensuring a stable and reliable output current. When the second transistor T2 is turned off, the ground path of the first resistor R1 is broken, the first voltage regulator U1 and the first transistor T1 stop working, and the first constant current circuit 1 has no current output.

[0055] With the above structure, the first constant current circuit 1 can stably output a set discharge current under the control of the main controller 4, so as to enable the supercapacitor pack to quickly pass through the initial nonlinear discharge region, thereby improving measurement efficiency and discharge control accuracy.

[0056] In one alternative implementation, such as Figure 4 As shown, the second constant current circuit 2 includes: a second voltage regulator U2, a third transistor T3, a fourth transistor T4, and a second resistor R2. The first terminal of the third transistor T3 is connected to the current switching circuit 3. The second terminal of the third transistor T3 is connected to both the first terminal of the second resistor R2 and the reference terminal of the second voltage regulator U2. The control terminal of the third transistor T3 is connected to both the cathode of the second voltage regulator U2 and the DC power supply. The anode of the second voltage regulator U2 is grounded. The first terminal of the fourth transistor T4 is connected to the second terminal of the second resistor R2. The control terminal of the fourth transistor T4 is connected to the second output terminal of the main controller 4. The second terminal of the fourth transistor T4 is grounded.

[0057] Specifically, when the main controller 4 outputs a control signal through the second output terminal GPIO2 to turn on the fourth transistor T4, the second resistor R2 forms a path to ground, and the second voltage regulator U2 enters the working state. The second voltage regulator U2 stabilizes its reference voltage at the reference voltage, thereby driving and adjusting the conduction state of the third transistor T3, so that the third transistor T3 operates in a constant current output state. The second resistor R2 serves as a current setting resistor, and the magnitude of the discharge current output by the second constant current circuit 2 can be flexibly adjusted by changing its resistance value.

[0058] The third transistor T3 acts as a constant current regulator. Under the closed-loop regulation of the second voltage regulator U2, it maintains a constant discharge current, unaffected by power supply voltage fluctuations, temperature changes, and supercapacitor voltage variations, ensuring a stable and reliable output current. When the fourth transistor T4 is turned off, the ground path of the second resistor R2 is broken, the second voltage regulator U2 and the third transistor T3 stop working, and the second constant current circuit 2 has no current output.

[0059] With the above structure, the second constant current circuit 2 can output a stable small current under the control of the main controller 4, providing high-precision measurement conditions for the supercapacitor pack in the CD linear discharge range, and further improving the accuracy and consistency of capacitance detection.

[0060] In one alternative implementation, the resistance of the first resistor R1 is less than the resistance of the second resistor R2.

[0061] Specifically, in order to make the discharge current output by the first constant current circuit 1 greater than the discharge current output by the second constant current circuit 2, this embodiment sets the resistance values ​​of the first resistor R1 and the second resistor R2 to be matched, so that the resistance value of the first resistor R1 is less than the resistance value of the second resistor R2, thereby setting the first constant current circuit 1 to a 0.2C high current discharge mode and the second constant current circuit 2 to a 0.05C low current discharge mode.

[0062] In a constant current output circuit, the discharge current is inversely proportional to the resistance value of the set resistor. Assuming the reference voltage of the regulated source remains constant, the smaller the resistance value, the larger the output current of the constant current circuit. Therefore, configuring the resistance of the first resistor R1 to be smaller than that of the second resistor R2 allows the first constant current circuit 1 to output a larger amplitude first discharge current, meeting the requirement of quickly passing through the nonlinear discharge region; simultaneously, it allows the second constant current circuit 2 to output a smaller amplitude second discharge current, meeting the requirement of stable and high-precision measurement within the linear region.

[0063] With the above resistance configuration, there is no need to change the voltage regulator parameters and control logic. Two constant discharge currents of different magnitudes can be output simply by the difference in resistance value. Combined with the current switching circuit, adaptive segmented discharge is completed, which improves measurement efficiency while ensuring the accuracy and stability of capacitance calculation.

[0064] In one alternative implementation, such as Figure 4 As shown, the system also includes a voltage divider circuit 5, which includes a third resistor R3 and a fourth resistor R4. The first terminal of the third resistor R3 is connected to the DC power supply P12V. The second terminal of the third resistor R3 is connected to the first terminal of the fourth resistor R4, the cathode of the first voltage regulator U1, the cathode of the second voltage regulator U2, the control terminal of the first transistor T1, and the control terminal of the third transistor T3. The other terminal of the fourth resistor R4 is grounded.

[0065] Specifically, the DC power supply P12V input voltage is divided by the third resistor R3 and the fourth resistor R4, forming a fixed bias voltage at the connection node of the two resistors. This bias voltage is simultaneously applied to the cathodes of the first voltage regulator U1 and the second voltage regulator U2, as well as the control terminals of the first transistor T1 and the third transistor T3, providing the aforementioned devices with a start-up voltage and a static operating point that meet the operating requirements.

[0066] By properly configuring the resistance ratio of the third resistor R3 and the fourth resistor R4, the P12V power supply voltage can be reduced to a safe voltage range suitable for the voltage regulator and the transistor control electrode, avoiding damage to the devices due to excessive voltage. Simultaneously, it ensures the reliable startup and stable operation of the first constant current circuit 1 and the second constant current circuit 2. The voltage divider circuit 5 provides a unified bias power supply for the two constant current circuits, simplifying the circuit structure and improving system consistency and reliability.

[0067] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method.

[0068] The supercapacitor measurement system provided in this application adopts an architecture combining dual-channel constant current segmented discharge and dynamic threshold determination. It can calculate the linear measurement range in real time based on temperature, discharge current, and equivalent series resistance, and accurately identify stable measurement segments using voltage change rate. This effectively avoids interference from the initial ESR nonlinear region and the end-diffusion effect, fundamentally improving capacitance detection accuracy. The system achieves millisecond-level current switching through high-speed optocouplers, enabling rapid discharge of large currents and precise measurement of small currents, balancing detection efficiency and measurement stability. Furthermore, the overall solution possesses strong adaptability to various operating conditions and anti-interference capabilities, adapting to supercapacitors with different operating environments and aging levels. The measurement results are reliable and highly consistent, meeting the high-precision and high-reliability capacitance parameter detection requirements of industrial sites.

[0069] The supercapacitor measurement method and system provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and its core ideas. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A method for measuring supercapacitors, characterized in that, include: Discharge the supercapacitor pack according to the first discharge current; The starting and ending voltages of the linear region are dynamically calculated based on the real-time temperature, current discharge current, and equivalent series resistance of the supercapacitor pack. After determining that the supercapacitor pack has entered the linear discharge region, the supercapacitor pack is discharged according to the second discharge current, which is less than the first discharge current. The capacitance value is measured within the range where the voltage of the supercapacitor pack drops from the starting voltage to the ending voltage.

2. The supercapacitor measurement method according to claim 1, characterized in that, The conditions for determining whether a supercapacitor has entered the linear discharge region include: The voltage of the supercapacitor pack is less than or equal to the starting voltage, and its voltage change rate is greater than a preset voltage change rate threshold.

3. The supercapacitor measurement method according to claim 1, characterized in that, The formula for calculating the starting voltage of the linear region is as follows: V1 = V_max - I × ESR_T Where V1 is the starting voltage of the linear region; V_max is the initial voltage of the supercapacitor pack; I is the current discharge current; ESR_T is the equivalent series resistance after temperature compensation, ESR_T=ESR_25℃×[1+k1×(T-25)], ESR_25℃ is the equivalent series resistance of the supercapacitor pack under the standard environment of 25℃, k1 is the proportional coefficient, and T is the current temperature.

4. The supercapacitor measurement method according to claim 1, characterized in that, The formula for calculating the end voltage of the linear region is as follows: V2=V_min+k2×I×(1+αΔT)+V_offset Where V2 is the end voltage of the linear region, V_min is the cutoff voltage of the supercapacitor pack, k2 is the current influence coefficient, α is the temperature coefficient, ΔT is the temperature change, and V_offset is the safety margin.

5. The supercapacitor measurement method according to claim 2, characterized in that, The formula for calculating the preset voltage change rate threshold is as follows: dv_threshol / dt=-k1×I×(1+αΔT) Where dv_threshol / dt is the preset voltage change rate threshold.

6. A supercapacitor measurement system, characterized in that, For implementing the method of any one of claims 1 to 5, the system comprises: a first constant current circuit, a second constant current circuit, a current switching circuit, and a main controller, wherein, The first terminal of the current switching circuit is connected to the supercapacitor pack, and the second terminal of the current switching circuit is connected to the first terminal of the first constant current circuit and the first terminal of the second constant current circuit respectively. The control terminal of the current switching circuit is connected to the first output terminal of the main controller. The current switching circuit is used to receive the switching signal sent by the main controller, and in response to the first switching signal, the path from the first constant current circuit to the supercapacitor pack is opened, and in response to the second switching signal, the path from the second constant current circuit to the supercapacitor pack is opened. The discharge current of the second constant current circuit is less than the discharge current of the first constant current circuit. The main controller's acquisition terminal is connected to the supercapacitor pack. The main controller is used to dynamically calculate the starting voltage and ending voltage of the linear region based on the real-time temperature of the supercapacitor pack, the current discharge current, and the equivalent series resistance. During the initial discharge phase, the main controller sends a first switching signal to the current switching circuit. After determining that the supercapacitor pack has entered the linear discharge region, it sends a second switching signal and calculates the capacitance value within the linear discharge region.

7. The supercapacitor measurement system according to claim 6, characterized in that, The first constant current circuit includes: a first voltage regulator, a first transistor, a second transistor, and a first resistor, wherein, The first terminal of the first transistor is connected to the current switching circuit, the second terminal of the first transistor is connected to the first terminal of the first resistor and the reference terminal of the first voltage regulator, the control terminal of the first transistor is connected to the cathode of the first voltage regulator and the DC power supply, and the anode of the first voltage regulator is grounded. The first terminal of the second transistor is connected to the second terminal of the first resistor, the control terminal of the second transistor is connected to the second output terminal of the main controller, and the second terminal of the second transistor is grounded.

8. The supercapacitor measurement system according to claim 7, characterized in that, The second constant current circuit includes: a second voltage regulator, a third transistor, a fourth transistor, and a second resistor, wherein, The first terminal of the third transistor is connected to the current switching circuit, the second terminal of the third transistor is connected to the first terminal of the second resistor and the reference terminal of the second voltage regulator, the control terminal of the third transistor is connected to the cathode of the second voltage regulator and the DC power supply, and the anode of the second voltage regulator is grounded. The first terminal of the fourth transistor is connected to the second terminal of the second resistor, the control terminal of the fourth transistor is connected to the second output terminal of the main controller, and the second terminal of the fourth transistor is grounded.

9. The supercapacitor measurement system according to claim 8, characterized in that, The resistance of the first resistor is less than the resistance of the second resistor.

10. The supercapacitor measurement system according to claim 8, characterized in that, The system further includes a voltage divider circuit, which comprises a third resistor and a fourth resistor, wherein... The first end of the third resistor is connected to a DC power supply, the second end of the third resistor is connected to the first end of the fourth resistor, the cathode of the first voltage regulator, the cathode of the second voltage regulator, the control terminal of the first transistor, and the control terminal of the third transistor, respectively, and the other end of the fourth resistor is grounded.

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