A control method for a fuel cell voltage patrol multi-channel selector
By predicting the equivalent output impedance of the fuel cell voltage detector in real time and dynamically adjusting the capacitor and damping resistor, the problem of imbalance between accuracy and switching speed in the existing technology is solved, achieving high accuracy and fast switching.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- INNER MONGOLIA UNIVERSITY
- Filing Date
- 2026-04-22
- Publication Date
- 2026-06-30
AI Technical Summary
Existing fuel cell voltage monitors cannot balance the accuracy of the equipment with the switching speed, resulting in slow response and low readings.
By predicting the equivalent output impedance in real time based on the current input impedance and historical internal resistance, the holding capacitor and equivalent damping resistor are dynamically adjusted to match the target capacitor level and charging/discharging time constant, thereby optimizing the charging/discharging process.
It achieves the goal of maintaining sampling accuracy throughout the entire life cycle and automatically adapting to changes in battery internal resistance during high-frequency inspections, ensuring switching speed and accuracy.
Smart Images
Figure CN122092428B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of fuel cell technology, and in particular to a control method for a multi-channel selector for fuel cell voltage monitoring. Background Technology
[0002] The fuel cell voltage monitor is one of the core components of a fuel cell stack and system, responsible for acquiring the voltage of hundreds or thousands of fuel cell cells connected in series. Typically, the voltage monitor is designed as a separate module, and the voltage values acquired by it are reported to the system controller via communication for subsequent decision-making. The voltage monitor usually consists of two parts: a multi-channel selection section that enables the selection of circuit leads and channels for hundreds or thousands of fuel cell cells; and an analog-to-digital conversion section that acquires the voltage of the corresponding fuel cell cell for each channel.
[0003] In existing technologies, a fixed value of holding capacitor is usually used. This method makes it impossible for the voltage monitor to sense changes in the back-end circuit and battery internal resistance in real time and make corresponding adjustments. This can easily lead to problems such as incomplete charging during switching, low readings, or slow system response speed, thus failing to balance the accuracy of the equipment with the switching speed. Summary of the Invention
[0004] This application provides a control method for a multi-channel selector for fuel cell voltage inspection, which solves the problem of balancing equipment accuracy and switching speed in the prior art, and improves equipment accuracy and response speed during the inspection process.
[0005] To achieve the above objectives, the technical solution of this application embodiment is as follows:
[0006] In a first aspect, embodiments of this application provide a control method for a fuel cell voltage monitoring multi-channel selector, the method comprising:
[0007] When switching battery channels using at least one single-cell two-channel selection module, the equivalent output impedance of the channel to be switched is determined based on the current input impedance and historical internal resistance.
[0008] Based on the equivalent output impedance, the target capacitance value and target capacitance level of the holding capacitor in the signal holding circuit are determined, the holding capacitor is adjusted to the target capacitance level, and the charging current during the charging and discharging process is adjusted according to the target capacitance level.
[0009] The actual charge / discharge time constant is determined based on the equivalent output impedance and the target capacitance value.
[0010] Based on the actual charge / discharge time constant and the maximum charge / discharge time constant, adjust the equivalent damping resistance of the signal holder so that the actual charge / discharge time constant matches the maximum charge / discharge time constant.
[0011] In one possible implementation, determining the equivalent output impedance of the channel to be switched based on the current input impedance and historical data includes:
[0012] Determine the voltage change of each channel within the historical period;
[0013] The historical internal resistance is determined based on the voltage change and the sampling current.
[0014] The equivalent output impedance is obtained based on the input impedance and the historical internal resistance, combined with the preset impedance determination formula.
[0015] In one possible implementation, determining the target capacitance value and target capacitance level of the holding capacitor in the signal holder based on the equivalent output impedance, adjusting the holding capacitor to the target capacitance level, and adjusting the charging current during the charging and discharging process according to the target capacitance level includes:
[0016] Based on the target capacitance value, the target capacitance level is determined from a plurality of preset capacitance levels, and the holding capacitor is adjusted to the target capacitance level; the preset capacitance level is a high level, a medium level, or a low level;
[0017] When the target capacitor level is high or medium, all sub-capacitors of the holding capacitor are connected, and the channel to be switched is controlled to operate at the maximum charging current.
[0018] When the target capacitor level is low, a charging current adjustment value is determined based on the difference between the voltage of the holding capacitor and the target voltage, and the charging current is adjusted according to the charging current adjustment value; the target voltage is the open circuit voltage of the channel to be switched.
[0019] In one possible implementation, adjusting the equivalent damping resistance of the signal holding circuit based on the actual charge / discharge time constant and the maximum charge / discharge time constant to match the maximum charge / discharge time constant includes:
[0020] The signal establishment time is determined based on the sampling frequency at the current moment, and the maximum charge / discharge time constant is determined in combination with the establishment coefficient;
[0021] If the actual charge / discharge time constant is less than or equal to the maximum charge / discharge time constant, the total resistance is determined based on the target charge / discharge time constant and the target capacitance value.
[0022] Based on the total resistance and the equivalent output impedance, determine the target equivalent damping resistance;
[0023] Adjust the variable resistor connected in series with the holding capacitor to adjust the equivalent damping resistance to the target equivalent damping resistance.
[0024] In one possible implementation, the method further includes:
[0025] If the actual charge / discharge time constant is greater than the maximum charge / discharge time constant, a dynamic adjustment strategy is executed to make the actual charge / discharge time constant less than or equal to the maximum charge / discharge time constant.
[0026] The dynamic adjustment strategy involves adjusting the target capacitance level, adjusting the setup coefficient, or adjusting the sampling frequency.
[0027] In one possible implementation, the method further includes:
[0028] Based on the output current of the fuel cell, the rate of change of current is determined, and the current operating state of the fuel cell is determined according to the rate of change of current.
[0029] When the operating state is in the loading or unloading state, increase the switching frequency of the battery channel;
[0030] When the operating state is stable, the switching frequency is reduced.
[0031] In one possible implementation, the method further includes:
[0032] The electrical parameters of the input harness are collected to determine the number of connected battery channels; the electrical parameters are voltage and / or current.
[0033] The inspection range is determined based on the number of battery channels, and battery inspections are carried out according to the inspection range.
[0034] Secondly, embodiments of this application provide a fuel cell voltage monitoring multi-channel selector, which is used to execute the control method of the fuel cell voltage monitoring multi-channel selector of the first aspect; the multi-channel selector consists of an input harness, at least one single-cell two-channel selection module, a signal holding circuit, a post-stage sampling module, and a control module; the single-cell two-channel selection module has the signal holding circuit built into it; the single-cell two-channel selection module is connected to the input harness and the post-stage sampling module; the control module is connected to both the single-cell two-channel selection module and the post-stage sampling module;
[0035] The control module is configured to, when switching battery channels via at least one single-cell two-channel selection module, determine the equivalent output impedance of the channel to be switched based on the current input impedance and historical internal resistance; based on the equivalent output impedance, determine the target capacitance value and target capacitance level of the holding capacitor in the signal holder, adjust the holding capacitor to the target capacitance level, and adjust the charging current during the charging and discharging process according to the target capacitance level; determine the actual charging and discharging time constant based on the equivalent output impedance and the target capacitance value; and adjust the equivalent damping resistance of the signal holder according to the actual charging and discharging time constant and the maximum charging and discharging time constant, so that the actual charging and discharging time constant matches the maximum charging and discharging time constant.
[0036] The technical solutions provided in this application embodiment have at least the following technical effects or advantages:
[0037] By combining input impedance and historical internal resistance, the equivalent output impedance of the battery is predicted in real time, and the charging strategy is dynamically adjusted based on the equivalent output impedance to ensure sampling accuracy throughout the entire life cycle. During high-frequency inspection, the equivalent damping resistor is adjusted to ensure that the inspection can automatically adapt to changes in battery internal resistance, so as to maintain sampling accuracy while ensuring switching speed. Attached Figure Description
[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0039] Figure 1 A flowchart illustrating a control method for a fuel cell voltage monitoring multi-channel selector provided in this application embodiment;
[0040] Figure 2 This is a block diagram of a multi-channel selector for fuel cell voltage monitoring provided in an embodiment of this application. Detailed Implementation
[0041] 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, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0042] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.
[0043] Figure 1 This is a block diagram of a multi-channel selector for fuel cell voltage monitoring provided in an embodiment of this application. Figure 1 As shown, the method includes the following steps.
[0044] S101. When switching battery channels using at least one single-cell two-channel selection module, determine the equivalent output impedance of the channel to be switched based on the current input impedance and historical internal resistance.
[0045] S102. Based on the equivalent output impedance, determine the target capacitance value and target capacitance level of the holding capacitor in the signal holding circuit, adjust the holding capacitor to the target capacitance level, and adjust the charging current during the charging and discharging process according to the target capacitance level.
[0046] S103. Determine the actual charging and discharging time constant based on the equivalent output impedance and the target capacitance value.
[0047] S104. Based on the actual charge / discharge time constant and the maximum charge / discharge time constant, adjust the equivalent damping resistance of the signal holder so that the actual charge / discharge time constant matches the maximum charge / discharge time constant.
[0048] By combining input impedance and historical internal resistance, the equivalent output impedance of the battery is predicted in real time, and the charging strategy is dynamically adjusted based on the equivalent output impedance to ensure sampling accuracy throughout the entire life cycle. During high-frequency inspection, the equivalent damping resistor is adjusted to ensure that the inspection can automatically adapt to changes in battery internal resistance, so as to maintain sampling accuracy while ensuring switching speed.
[0049] In one possible implementation, S101 may include: determining the voltage change of each channel within a historical period; determining the historical internal resistance based on the voltage change and the sampling current; and obtaining the equivalent output impedance based on the input impedance and the historical internal resistance, combined with a preset impedance determination formula.
[0050] For example, the voltage change is determined by the following formula: ;in, This is the change in voltage. The voltage before connecting the load. This is the voltage after the load is connected. The historical internal resistance is determined using the following formula: ;in, Due to historical internal obstacles, The sampling current is used. The formula for determining the preset impedance is: ;in, For equivalent output impedance, The smoothing factor is set to 0.2-0.5. This refers to the inspection cycle.
[0051] In one possible implementation, S102 may include: determining the target capacitor level from a plurality of preset capacitor levels based on the target capacitor value, and adjusting the holding capacitor to the target capacitor level; the preset capacitor level is a high level, a medium level, or a low level; when the target capacitor level is a high level or a medium level, connecting all the sub-capacitors of the holding capacitor, and controlling the channel to be switched to operate at the maximum charging current; when the target capacitor level is a low level, determining a charging current adjustment value based on the difference between the voltage of the holding capacitor and the target voltage, and adjusting the charging current according to the charging current adjustment value; the target voltage is the open circuit voltage of the channel to be switched.
[0052] For example, the high setting is between 8-12nF, such as 8nF, 10nF or 12nF; the medium setting is between 0.5-2nF, such as 0.5nF, 1nF or 2nF; the low setting is between 90-110pF, such as 90nF, 100nF or 110nF, and there are no restrictions here.
[0053] In one possible implementation, S104 may include: determining the signal setup time based on the sampling frequency at the current moment, and determining the maximum charge / discharge time constant in combination with the setup coefficient; if the actual charge / discharge time constant is less than or equal to the maximum charge / discharge time constant, determining the total resistance based on the target charge / discharge time constant and the target capacitance value; determining the target equivalent damping resistance based on the total resistance and the equivalent output impedance; and adjusting the variable resistor connected in series with the holding capacitor to adjust the equivalent damping resistance to the target equivalent damping resistance.
[0054] For example, the signal setup time is determined by the following formula: ;in, For signal setup time, Sampling frequency, For analog-to-digital conversion time, For channel switching time, This is the safety margin factor. The maximum charge / discharge time constant is determined by the following formula: ;in, The maximum charge / discharge time constant. For signal setup time, To establish the coefficient, a value of 3-5 is used. The actual charge / discharge time constant is determined by the following formula: ;in, This is the actual charge / discharge time constant. For equivalent output impedance, The target capacitance value.
[0055] The target charge / discharge time constant is determined based on this maximum charge / discharge time constant, and the formula is as follows: ;in, The target charge / discharge time constant, For coefficients, take values , This is the maximum charge / discharge time constant. The total resistance is determined by the following formula: ;in, The total resistance is... The target charge / discharge time constant, The target capacitance value is given by the following formula: ;in, The target equivalent damping resistance. The total resistance is... This is the equivalent output impedance.
[0056] In one possible implementation, the method may further include: if the actual charge / discharge time constant is greater than the maximum charge / discharge time constant, executing a dynamic adjustment strategy to make the actual charge / discharge time constant less than or equal to the maximum charge / discharge time constant; the dynamic adjustment strategy may be adjusting the target capacitance level, adjusting the setup coefficient, or adjusting the sampling frequency. For example, adjusting the target capacitance level may involve lowering the target capacitance level to reduce the target capacitance value; adjusting the setup coefficient may involve lowering the setup coefficient; and adjusting the sampling frequency may involve lowering the sampling frequency.
[0057] In one possible implementation, the method further includes: determining a current change rate based on the output current of the fuel cell, and determining the current operating state of the fuel cell based on the current change rate; increasing the switching frequency of the battery channel when the operating state is a loaded state or an unloaded state; and decreasing the switching frequency when the operating state is a stable state.
[0058] For example, if the rate of change of current is greater than the positive rate of change threshold, the operating state is determined to be a loading state; if the rate of change of current is less than the negative rate of change threshold, the operating state is determined to be an unloading state; if the rate of change of current is less than or equal to the upper limit of the allowable rate of change of the steady state, the operating state is determined to be a steady state.
[0059] In one possible implementation, the method further includes: acquiring electrical parameters of the input harness to determine the number of connected battery channels; the electrical parameters being voltage and / or current; determining the inspection range based on the number of battery channels; and performing battery inspection according to the inspection range.
[0060] In some embodiments, the method may further include: adding a preset switching time to the signal establishment time, and then acquiring the voltage through a subsequent sampling module after the fuel cell has entered a stable state. For example, the signal establishment time can be 100 μs to 300 μs; the preset switching time can be 500 μs. This allows for precise control via an internal timer, ensuring the signal remains stable at the sampling time.
[0061] In some embodiments, the method may further include: performing a selection on a battery channel in the at least one single-cell battery two-channel selection module, and detecting whether there is a signal output at the output terminal; if there is no output signal after the first battery channel is selected, it is determined that the first battery channel has an open circuit fault; if there is still an output signal after the second battery channel is not selected, it is determined that the second battery channel has a short circuit fault.
[0062] In other embodiments, the method may further include: determining the connection status between the input harness and the fuel cell based on the input impedance of each lead of the input harness; when the input impedance is greater than 10... In such cases, the input harness is determined to have a poor contact fault or a broken wire fault.
[0063] Figure 2 This is a block diagram of a multi-channel selector for fuel cell voltage monitoring provided in an embodiment of this application. Figure 2As shown, the multi-channel selector 200 is used to execute a control method for a fuel cell voltage inspection multi-channel selector. The multi-channel selector 200 consists of an input harness 210, at least one single-cell two-channel selection module 220, a signal holding circuit 230, a post-stage sampling module 240, and a control module 250. The single-cell two-channel selection module 220 integrates the signal holding circuit 230. The single-cell two-channel selection module 220 is connected to the input harness 210 and the post-stage sampling module 240. The control module 250 is connected to both the single-cell two-channel selection module 220 and the post-stage sampling module 240.
[0064] The control module 250 is used to determine the equivalent output impedance of the channel to be switched based on the current input impedance and historical internal resistance when switching battery channels through at least one single-cell two-channel selection module; based on the equivalent output impedance, determine the target capacitance value and target capacitance level of the holding capacitor in the signal holder, adjust the holding capacitor to the target capacitance level, and adjust the charging current during the charging and discharging process according to the target capacitance level; determine the actual charging and discharging time constant based on the equivalent output impedance and the target capacitance value; and adjust the equivalent damping resistance of the signal holder according to the actual charging and discharging time constant and the maximum charging and discharging time constant so that the actual charging and discharging time constant matches the maximum charging and discharging time constant.
[0065] By combining input impedance and historical internal resistance, the equivalent output impedance of the battery is predicted in real time, and the charging strategy is dynamically adjusted based on the equivalent output impedance, ensuring sampling accuracy throughout the entire life cycle. This enables the signal holder to output a high-precision, low-noise hold signal in adjacent channel switching scenarios, ensuring that the subsequent sampling module obtains accurate voltage data. Furthermore, during high-frequency inspection, the equivalent damping resistor is adjusted to ensure that the inspection can automatically adapt to changes in battery internal resistance, maintaining sampling accuracy while ensuring switching speed.
[0066] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.
[0067] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.
Claims
1. A control method for a multi-channel selector for fuel cell voltage monitoring, characterized in that, The method includes: When switching battery channels using at least one single-cell two-channel selection module, the equivalent output impedance of the battery in the channel to be switched is determined based on the current input impedance and historical internal resistance. Based on the equivalent output impedance, the target capacitance value and target capacitance level of the holding capacitor in the signal holding circuit are determined, the holding capacitor is adjusted to the target capacitance level, and the charging current during the charging and discharging process is adjusted according to the target capacitance level. The actual charge / discharge time constant is determined based on the equivalent output impedance and the target capacitance value. Based on the actual charge / discharge time constant and the maximum charge / discharge time constant, adjust the equivalent damping resistance of the signal holder so that the actual charge / discharge time constant matches the maximum charge / discharge time constant; The step of adjusting the equivalent damping resistance of the signal holding circuit based on the actual charge / discharge time constant and the maximum charge / discharge time constant includes: The signal establishment time is determined based on the sampling frequency at the current moment, and the maximum charge / discharge time constant is determined in combination with the establishment coefficient; If the actual charge / discharge time constant is less than or equal to the maximum charge / discharge time constant, the total resistance is determined based on the target charge / discharge time constant and the target capacitance value. Based on the total resistance and the equivalent output impedance, determine the target equivalent damping resistance; Adjust the variable resistor connected in series with the holding capacitor to adjust the equivalent damping resistance to the target equivalent damping resistance; The signal establishment time is determined by the following formula: ;in, For signal setup time, Sampling frequency, For analog-to-digital conversion time, For channel switching time, This refers to the safety margin factor. The maximum charge / discharge time constant is determined by the following formula: ;in, The maximum charge / discharge time constant. For signal setup time, To establish the coefficients, the values are 3-5; The actual charge / discharge time constant is determined by the following formula: ;in, This is the actual charge / discharge time constant. For equivalent output impedance, The target capacitance value; The target charge / discharge time constant is determined based on the maximum charge / discharge time constant, and the formula is as follows: ;in, The target charge / discharge time constant, For coefficients, take values , This represents the maximum charge / discharge time constant. The total resistance is determined by the following formula: ;in, The total resistance is... The target charge / discharge time constant, The target capacitance value; The target equivalent damping resistance is determined by the following formula: ;in, The target equivalent damping resistance. The total resistance is... This is the equivalent output impedance.
2. The method according to claim 1, characterized in that, The determination of the equivalent output impedance of the battery in the channel to be switched, based on the current input impedance and historical internal resistance, includes: Determine the voltage change of each channel within the historical period; The historical internal resistance is determined based on the voltage change and the sampling current. The equivalent output impedance is obtained based on the input impedance and the historical internal resistance, combined with the preset impedance determination formula.
3. The method according to claim 1, characterized in that, The step of determining the target capacitance value and target capacitance level of the holding capacitor in the signal hold circuit based on the equivalent output impedance, adjusting the holding capacitor to the target capacitance level, and adjusting the charging current during the charging and discharging process according to the target capacitance level includes: Based on the target capacitance value, the target capacitance level is determined from a plurality of preset capacitance levels, and the holding capacitor is adjusted to the target capacitance level; the preset capacitance level is a high level, a medium level, or a low level; When the target capacitor level is high or medium, all sub-capacitors of the holding capacitor are connected, and the battery of the channel to be switched is controlled to operate at the maximum charging current. When the target capacitor level is low, a charging current adjustment value is determined based on the difference between the voltage of the holding capacitor and the target voltage, and the charging current is adjusted according to the charging current adjustment value; the target voltage is the open circuit voltage of the battery of the channel to be switched.
4. The method according to claim 1, characterized in that, The method further includes: If the actual charge / discharge time constant is greater than the maximum charge / discharge time constant, a dynamic adjustment strategy is executed to make the actual charge / discharge time constant less than or equal to the maximum charge / discharge time constant. The dynamic adjustment strategy involves adjusting the target capacitance level, adjusting the setup coefficient, or adjusting the sampling frequency.
5. The method according to claim 1, characterized in that, The method further includes: Based on the output current of the fuel cell, the rate of change of current is determined, and the current operating state of the fuel cell is determined according to the rate of change of current. When the operating state is in the loading or unloading state, increase the switching frequency of the battery channel; When the operating state is stable, the switching frequency is reduced.
6. The method according to claim 1, characterized in that, The method further includes: The electrical parameters of the input harness are collected to determine the number of connected battery channels; the electrical parameters are voltage and / or current. The inspection range is determined based on the number of battery channels, and battery inspections are carried out according to the inspection range.
7. A multi-channel selector for fuel cell voltage monitoring, characterized in that, The multi-channel selector is used to execute the control method of a fuel cell voltage inspection multi-channel selector according to any one of claims 1 to 6; the multi-channel selector consists of an input harness, at least one single-cell two-channel selection module, a signal hold circuit, a post-stage sampling module, and a control module; the single-cell two-channel selection module has the signal hold circuit built into it; the single-cell two-channel selection module is connected to the input harness and the post-stage sampling module; the control module is connected to both the single-cell two-channel selection module and the post-stage sampling module; The control module is configured to, when switching battery channels via at least one single-cell two-channel selection module, determine the equivalent output impedance of the channel to be switched based on the current input impedance and historical internal resistance; based on the equivalent output impedance, determine the target capacitance value and target capacitance level of the holding capacitor in the signal holder, adjust the holding capacitor to the target capacitance level, and adjust the charging current during charging and discharging according to the target capacitance level; determine the actual charging and discharging time constant based on the equivalent output impedance and the target capacitance value; and adjust the equivalent damping resistance of the signal holder based on the actual charging and discharging time constant and the maximum charging and discharging time constant to ensure that the actual charging and discharging time is within acceptable limits. The process of matching the actual charge / discharge time constant with the maximum charge / discharge time constant, and adjusting the equivalent damping resistance of the signal holder based on the actual charge / discharge time constant and the maximum charge / discharge time constant, includes: determining the signal setup time based on the sampling frequency at the current moment, and determining the maximum charge / discharge time constant in combination with the setup coefficient; determining the total resistance based on the target charge / discharge time constant and the target capacitance value when the actual charge / discharge time constant is less than or equal to the maximum charge / discharge time constant; determining the target equivalent damping resistance based on the total resistance and the equivalent output impedance; and adjusting the variable resistor connected in series with the holding capacitor to adjust the equivalent damping resistance to the target equivalent damping resistance. The signal establishment time is determined by the following formula: ;in, For signal setup time, Sampling frequency, For analog-to-digital conversion time, For channel switching time, The safety margin factor; the maximum charge / discharge time constant is determined by the following formula: ;in, The maximum charge / discharge time constant. For signal setup time, To establish the coefficient, a value of 3-5 is used; the actual charge / discharge time constant is determined by the following formula: ;in, This is the actual charge / discharge time constant. For equivalent output impedance, The target capacitance value; the target charge / discharge time constant is determined based on the maximum charge / discharge time constant, using the following formula: ;in, The target charge / discharge time constant, For coefficients, take values , The maximum charge / discharge time constant is used; the total resistance is determined by the following formula: ;in, The total resistance is... The target charge / discharge time constant, The target capacitance value is given by the following formula: ;in, The target equivalent damping resistance. The total resistance is... This is the equivalent output impedance.