Charging and discharging method and circuit capable of prolonging service life of super capacitor of electric energy meter
By designing a charging and discharging circuit and method, the charging and discharging timing of the supercapacitor is controlled and the charge and discharge timing of the supercapacitor is kept in a self-held state for a long time, the problem of insufficient service life of the supercapacitor is solved, and the reliability of the supercapacitor's life is extended and the power outage reporting of the power meter is achieved.
Patent Information
- Application Number
- CN202411820115.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-02-28
AI Technical Summary
The prior art is difficult to effectively extend the service life of the supercapacitor of the electricity meter, resulting in potential problems in reporting power outages.
By designing a charging and discharging circuit and corresponding methods, the charging and discharging timing is controlled, the supercapacitor is in a self-held state for a long time, and the supercapacitor capacity is evaluated online, and the charging cut-off voltage is determined to extend the service life of the supercapacitor.
The long-term self-retaining state of the supercapacitor is achieved, which significantly extends its service life and ensures that the power outage reporting requirements are met during the life cycle of the power meter.
Smart Images
Figure CN119543384A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of super capacitors for electric energy meters, and specifically provides a charging and discharging method and a circuit for extending the service life of super capacitors for electric energy meters. Background Art
[0002] As a key component of the electricity meter, the life of the supercapacitor directly affects the power outage reporting capability of the electricity meter. Therefore, when the electricity meter is working, it is necessary to monitor the supercapacitor life information in real time and extend the service life of the supercapacitor as much as possible to ensure the normal operation of the electricity meter.
[0003] Since the power outage of the energy meter is a rare and occasional state, the supercapacitor is in a floating charge state for a long time. The current method to extend the life of the supercapacitor is to use it at a reduced rating. For example, if the highest voltage on site is 3.3V, a supercapacitor with a rated voltage of 5V is selected. This strategy will lead to a significant increase in cost and volume. At the same time, due to the limited internal space of the energy meter, the internal layout of the energy meter is relatively complex, and the life of the supercapacitor is not monitored. When the capacity decays, it will seriously affect the field application. Summary of the invention
[0004] In view of the life requirement of a supercapacitor of an electric energy meter and the working condition of the supercapacitor in the electric energy meter, the present invention proposes a charging and discharging method and a circuit that can extend the service life of the supercapacitor.
[0005] On one hand, the present invention provides a charging and discharging circuit that can extend the service life of a supercapacitor of an electric energy meter, the circuit comprising a constant current source I1, a constant current source I2, a supercapacitor C1, a supercapacitor C2, a switch S1, a switch S4, a current limiting switch S2, a current limiting switch S3, a power selection diode D1, a power selection diode D2, wherein: The constant current source I1, the switch S1, the super capacitor C1, and the super capacitor C2 are connected in series and are connected to the ACDC power supply output of the energy meter and the ground respectively; The ACDC power supply of the energy meter outputs voltage U1, which charges supercapacitors C1 and C2 through constant current source I1 and switch S1; The current limiting switch S2 and the current limiting switch S3 are respectively connected in parallel to the supercapacitor C1 and the supercapacitor C2 to balance the voltage of the supercapacitors; The constant current source I2 and the switch S4 are connected in series and then connected in parallel with the supercapacitors C1 and C2, so as to discharge the supercapacitors and evaluate the supercapacitor capacity online.
[0006] Furthermore, when there is AC power, the power supply output voltage U1 of the energy meter ACDC is turned off, and the power selection diode D2 is turned off, and power is supplied through the power selection diode D1; When the ACDC power supply of the energy meter has no output, the power selection diode D1 is cut off, and the super capacitors C1 and C2 are powered through the power selection diode D2.
[0007] Another aspect of the present invention provides a charging and discharging method capable of extending the service life of a supercapacitor of an electric energy meter. The method controls the charging and discharging timing so that the supercapacitor is in a self-maintaining state for a long time, thereby extending the service life of the supercapacitor. Determine the supercapacitor capacity through the cycle and determine the supercapacitor charging cut-off voltage U stop , ensuring that the supercapacitor meets the power outage reporting requirements of the electricity meter throughout the life cycle of the electricity meter.
[0008] Furthermore, the method comprises the following steps: Step 1: Initialize the supercapacitor charging cut-off voltage U stop ; The initial default parameters are used for the first run, and the U calculated in step 7 is used for subsequent runs. stop .
[0009] Disconnect switch S1, switch S4, current limiting switch S2, and current limiting switch S3; Initialize the AD pin of the electric energy meter main control chip and sample the voltage u of the supercapacitor C2 c2 (t), supercapacitor C is two supercapacitors C1 and C2 connected in series, and the voltage is u c (t); The voltage u of supercapacitor C1 c1 (t) is obtained through calculation, the formula is as follows: u c1 (t) = u c (t)-u c2 (t) Step 2, close the switch S1, open the current limiting switch S2, open the current limiting switch S3, open the switch S4, and charge the supercapacitors C1 and C2 through the constant current source I1; Step 3: Monitor the supercapacitor voltage u c (t) Is it greater than the charging cut-off voltage U stop , if the supercapacitor voltage u c (t) is greater than the charging cut-off voltage U stop , go to step 5 to put the supercapacitor in a self-holding state; If the supercapacitor voltage u c (t) is less than the charging cut-off voltage U stop , continue charging; Step 4: Monitor the voltage difference between supercapacitors C1 and C2 |u c1 (t)-u c2 (t)| is greater than 0.2V, If the voltage difference between supercapacitors C1 and C2 |u c1 (t)-u c2 (t)| is greater than 0.2V, close the current limiting switch of the supercapacitor with a larger single cell voltage to perform capacitor voltage balancing, and repeat step 4; If the voltage difference between supercapacitors C1 and C2 |u c1 (t)-u c2 (t)|The absolute value is less than or equal to 0.2V, turn off the current limiting switches S2 and S3, and return to step 3; Step 5: Turn off the switch S1 to put the supercapacitor in a self-holding state; Step 6: Detect the supercapacitor voltage u c Is (t) less than U? stop -△U, if yes, go to step 2, otherwise continue; Where △U is the hysteresis voltage of supercapacitor charging and discharging.
[0010] Step 7: Check whether the supercapacitor capacity test period T has been reached. If so, perform a supercapacitor capacity test and update U stop The value is stored and goes to step 6.
[0011] Furthermore, in step 6, the monitoring period value is 10 seconds, and the ΔU value is 0.4V.
[0012] Furthermore, the supercapacitor charging cut-off voltage U stop The calculation method is as follows:
[0013] Where: K is the compensation coefficient, which is used to compensate for the attenuation of the supercapacitor capacity within the period T and the energy loss generated when testing the capacity. The value range is between 1.0 and 1.1. U off is the supercapacitor discharge cut-off voltage, W is the energy required for the electric energy meter to report power outage information, and C is the real-time capacity of the supercapacitor.
[0014] Furthermore, the supercapacitor discharge cut-off voltage U off The value is 2.0V; In step 7, the supercapacitor capacity cycle T value is 30×24=720 hours.
[0015] Furthermore, the process of the supercapacitor capacity test in step 7 is as follows: Open switch S1, open current limiting switch S2, open current limiting switch S3, close switch S4, Use constant current source I2 to discharge the supercapacitor. The closing time of S4 is recorded as t1, and the supercapacitor voltage is recorded as uc (t1), At t2=(t1+2) seconds, the supercapacitor voltage is recorded as u c (t2), At t3=(t2+2) seconds, the supercapacitor voltage is recorded as u c (t3), At t4=(t3+1) seconds, disconnect switch S4 and record the supercapacitor voltage as u c (t4), using u c (t2),u c (t3), the real-time capacity C of the supercapacitor is measured, and the formula is as follows: Among them, i2 is the current of constant current source I2.
[0016] Furthermore, the relationship between the self-holding time and the supplementary charging time of the supercapacitor is shown in the following formula: C△U=I leak *t leak =i1*t ch Where: I leak is the self-maintaining leakage current, i1 is the current of the constant current source I1; The self-holding time t is obtained by calculation leak and capacitor replenishment time t ch , the self-holding time t leak and capacitor replenishment time t ch By comparison, the situation where the supercapacitor is in a self-maintaining state is obtained.
[0017] Compared with the prior art, the charging and discharging method and circuit of the present invention for extending the service life of the supercapacitor of the electric energy meter have the following outstanding beneficial effects: (1) By controlling the charge and discharge timing, the supercapacitor is kept in a self-maintaining state for a long time, thereby extending the service life of the supercapacitor. When the supercapacitor is in a floating charge state, the floating charge current will pass through the supercapacitor, which will accelerate the aging of the supercapacitor. When it is in a self-maintaining state, the supercapacitor only has its own leakage current, and its life is significantly longer than that in a floating charge state.
[0018] (2) Accurately evaluate the supercapacitor capacity online to determine the supercapacitor charging cut-off voltage, ensuring that the supercapacitor can meet the power outage reporting requirements of the power meter throughout the life cycle of the power meter. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a circuit schematic diagram of the present invention; Figure 2 It is a flow chart of the method of the present invention. DETAILED DESCRIPTION
[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.
[0021] like Figure 1 As shown, a charging and discharging circuit that can extend the service life of a supercapacitor of an electric energy meter is composed of a constant current source I1, a constant current source I2, supercapacitors C1, C2, switches S1, S4, current limiting switches S2, S3, and power selection diodes D1, D2.
[0022] Among them, U1 is the power output of the energy meter ACDC, which charges the supercapacitor through the constant current source I1 and switch S1. The current limiting switches S2 and S3 are connected in parallel to the supercapacitors C1 and C2 respectively to balance the voltage of the supercapacitors. The constant current source I2 and switch S4 are used to discharge the supercapacitor and evaluate the supercapacitor capacity online. When there is AC power, the ACDC has an output, D2 is cut off, and power is supplied through D1. When there is no output of ACDC, D1 is cut off, and the supercapacitor is powered through D2.
[0023] A charging and discharging method for extending the service life of a supercapacitor in an electric energy meter, such as Figure 2 As shown, the following steps are included: Step 1: Initialize the supercapacitor charging cut-off voltage U stop ; For the first run, use the default parameter of 5V; for subsequent runs, use the supercapacitor charging cut-off voltage U calculated in step 7. stop ; Disconnect switch S1, switch S4, current limiting switch S2, and current limiting switch S3; Initialize the AD pin of the electric energy meter main control chip and sample the voltage u of the supercapacitor C2 c2 (t), voltage u of supercapacitor C1+C2 c (t); The voltage of supercapacitor C1 is calculated using the following formula: u c1 (t) = u c (t)-u c2 (t) Step 2, close the switch S1, open the current limiting switch S2, open the current limiting switch S3, open the switch S4, and charge the supercapacitor through the constant current source I1; Step 3: Monitor the supercapacitor voltage u c (t) Is it greater than the charging cut-off voltage U stop , if yes, go to step 5, otherwise continue; Step 4: Monitor the supercapacitor cell voltage difference |u c1 (t)-u c2(t) | is the absolute value greater than 0.2V? If so, close the current limiting switch of the supercapacitor with a larger single cell voltage to perform capacitor voltage balancing, and repeat step 4; Otherwise, disconnect the current limiting switches S2 and S3 and return to step 3; Step 5: Turn off the switch S1 to put the supercapacitor in a self-holding state; Step 6: Periodically monitor the supercapacitor u c Is (t) less than U? stop -△U, if yes, go to step 2, otherwise continue; Where △U is the hysteresis voltage of supercapacitor charging and discharging, and its typical value is 0.4V; Step 7: Test whether the supercapacitor capacity cycle T (value is 30×24=720 hours) has been reached. If it has been reached, perform a supercapacitor capacity test and update U stop The value is stored and goes to step 6.
[0024] In step 6, the monitoring period value is 10 seconds, and the ΔU value is 0.4V.
[0025] The supercapacitor charging cut-off voltage U stop The calculation method is as follows:
[0026] Where: K is the compensation coefficient, which is used to compensate for the possible attenuation of the supercapacitor capacity within the period T and the energy loss generated when testing the capacity. The value range is between 1.0 and 1.1, and the typical value is 1.1. U off is the supercapacitor discharge cut-off voltage, which is 2.0V. W is the energy required for the electric energy meter to report the necessary information during a power outage, which is typically 6.6J. C is the real-time capacity of the supercapacitor, which is typically 1.5F. Therefore, according to the above formula, U stop =4.1V.
[0027] The process of performing supercapacitor capacity test in step 7 is as follows: Open switch S1, open current limiting switch S2, open current limiting switch S3, close switch S4, Use constant current source I2 to discharge the supercapacitor. The closing time of S4 is recorded as t1, and the supercapacitor voltage is recorded as u c (t1), At t2=(t1+2) seconds, the supercapacitor voltage is recorded as u c (t2), At t3=(t2+2) seconds, the supercapacitor voltage is recorded as u c (t3), At t4=(t3+1) seconds, disconnect switch S4 and record the supercapacitor voltage as uc (t4), considering the internal resistance of the supercapacitor, to ensure the accuracy of the calculation, u c (t1),u c (t4), using u c (t2),u c (t3), the real-time capacity C of the supercapacitor is measured, and the formula is as follows:
[0028] Among them, i2 is the current of constant current source I2, and the typical value is 10mA. Through testing, we can get u c (t2) = 3.125V, u c (t3)=3.111V, so we can calculate that C=1.429F.
[0029] The initial capacity of supercapacitors C1 and C2 is 3F. The supercapacitor C measured at the supercapacitor capacity period T is used to calculate U stop , return to step 1, as the initial charging cut-off voltage U stop ; According to the control process of the above steps, the supercapacitor is kept in a self-maintaining state for a long time, thereby increasing its service life. The verification process is as follows: The self-holding time and supplementary charging time are as follows: C△U=I leak *t leak =i1*t ch Where: Self-holding leakage current I leak is 5uA, constant current source current i1 is 50mA, Calculated: self-holding time t leak =5uA Capacitor replenishment time t ch =50mA Self-holding time t leak : Capacitor replenishment time t ch =10000:1, self-holding time t leak Much longer than the capacitor replenishment time t ch , from this we can see that the supercapacitor is in a self-maintaining state for a long time, thereby improving the life of the supercapacitor.
[0030] The embodiments described above are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.
Claims
1. A charging and discharging circuit capable of extending the service life of a supercapacitor of an electric energy meter, characterized in that: The circuit includes a constant current source I1, a constant current source I2, a super capacitor C1, a super capacitor C2, a switch S1, a switch S4, a current limiting switch S2, a current limiting switch S3, a power selection diode D1, a power selection diode D2, wherein: The constant current source I1, the switch S1, the super capacitor C1, and the super capacitor C2 are connected in series and are connected to the ACDC power supply output of the energy meter and the ground respectively; The ACDC power supply of the energy meter outputs voltage U1, which charges supercapacitors C1 and C2 through constant current source I1 and switch S1; The current limiting switch S2 and the current limiting switch S3 are respectively connected in parallel to the supercapacitor C1 and the supercapacitor C2 to balance the voltage of the supercapacitors; The constant current source I2 and the switch S4 are connected in series and then connected in parallel with the supercapacitors C1 and C2, so as to discharge the supercapacitors and evaluate the supercapacitor capacity online.
2. A charging and discharging circuit capable of extending the service life of a supercapacitor of an electric energy meter according to claim 1, characterized in that: When there is AC power, the power supply output voltage U1 of the energy meter ACDC is turned off, and the power supply selection diode D2 is cut off, and power is supplied through the power supply selection diode D1.
3. A charging and discharging circuit capable of extending the service life of a supercapacitor of an electric energy meter according to claim 1, characterized in that: When the ACDC power supply of the energy meter has no output, the power selection diode D1 is cut off, and the super capacitors C1 and C2 are powered through the power selection diode D2.
4. A charging and discharging circuit capable of extending the service life of a super capacitor of an electric energy meter and a charging and discharging method capable of extending the service life of a super capacitor of an electric energy meter based on any one of the above claims, characterized in that: The method controls the charging and discharging timing of the supercapacitor so that the supercapacitor is in a self-maintaining state for a long time, thereby extending the service life of the supercapacitor; Determine the supercapacitor capacity through the cycle and determine the supercapacitor charging cut-off voltage U stop , ensuring that the supercapacitor meets the power outage reporting requirements of the electricity meter throughout the life cycle of the electricity meter.
5. A charging and discharging method for extending the service life of a supercapacitor of an electric energy meter according to claim 4, characterized in that: The method comprises the following steps: Step 1: Initialize the supercapacitor charging cut-off voltage U stop ; Disconnect switch S1, switch S4, current limiting switch S2, and current limiting switch S3; Initialize the AD pin of the electric energy meter main control chip and sample the voltage u of the supercapacitor C2 c2 (t), the voltage after the supercapacitors C1 and C2 are connected in series is u c (t); The voltage u of supercapacitor C1 c1 (t) is obtained through calculation, the formula is as follows: u c1 (t)=u c (t)-u c2 (t) ; Step 2, close the switch S1, open the current limiting switch S2, open the current limiting switch S3, open the switch S4, and charge the supercapacitors C1 and C2 through the constant current source I1; Step 3: Monitor the supercapacitor voltage u c (t) Is it greater than the charging cut-off voltage U stop , if the supercapacitor voltage u c (t) is greater than the charging cut-off voltage U stop , go to step 5 to put the supercapacitor in a self-holding state; If the supercapacitor voltage u c (t) is less than the charging cut-off voltage U stop , continue charging; Step 4: Monitor the voltage difference between supercapacitors C1 and C2 |u c1 (t)-u c2 (t)| is greater than 0.2V, If the voltage difference between supercapacitors C1 and C2 |u c1 (t)-u c2 (t)| is greater than 0.2V, close the current limiting switch of the supercapacitor with a larger single cell voltage to perform capacitor voltage balancing, and repeat step 4; If the voltage difference between supercapacitors C1 and C2 |u c1 (t)-u c2 (t)|The absolute value is less than or equal to 0.2V, turn off the current limiting switches S2 and S3, and return to step 3; Step 5, turn off the switch S1 to put the supercapacitor in a self-holding state; Step 6: Detect the supercapacitor voltage u c Is (t) less than U? stop -△U, if yes, go to step 2, otherwise continue; Where △U is the hysteresis voltage of supercapacitor charging and discharging; Step 7: Check whether the supercapacitor capacity test period T has been reached. If so, perform a supercapacitor capacity test and update U stop The value is stored and goes to step 6.
6. A charging and discharging method for extending the service life of a supercapacitor of an electric energy meter according to claim 5, characterized in that: In step 6, the monitoring period value is 10 seconds, and the ΔU value is 0.4V.
7. A charging and discharging method for extending the service life of a supercapacitor of an electric energy meter according to claim 5, characterized in that: The supercapacitor charging cut-off voltage U stop The calculation method is as follows: ； Where: K is the compensation coefficient, which is used to compensate for the attenuation of the supercapacitor capacity within the period T and the energy loss generated when testing the capacity. The value range is between 1.0 and 1.
1. U off is the supercapacitor discharge cut-off voltage, W is the energy required for the electric energy meter to report power outage information, and C is the supercapacitor capacity.
8. A charging and discharging method for extending the service life of a supercapacitor of an electric energy meter according to claim 7, characterized in that: The supercapacitor discharge cut-off voltage U off The value is 2.0V; In step 7, the supercapacitor capacity cycle T value is 30×24=720 hours.
9. A charging and discharging method for extending the service life of a supercapacitor of an electric energy meter according to claim 7, characterized in that: The process of the supercapacitor capacity test in step 7 is as follows: Open switch S1, open current limiting switch S2, open current limiting switch S3, close switch S4, Use constant current source I2 to discharge the supercapacitor. The closing time of S4 is recorded as t1, and the supercapacitor voltage is recorded as u c (t1), At t2=(t1+2) seconds, the supercapacitor voltage is recorded as u c (t2), At t3=(t2+2) seconds, the supercapacitor voltage is recorded as u c (t3), At t4=(t3+1) seconds, disconnect switch S4 and record the supercapacitor voltage as u c (t4), using u c (t2),u c (t3), the real-time capacity C of the supercapacitor is measured, and the formula is as follows: ； Among them, i2 is the current size of constant current source I2.
10. A charging and discharging method for extending the service life of a supercapacitor of an electric energy meter according to claim 9, characterized in that: The relationship between the self-holding time and the supplementary charging time of the supercapacitor is shown in the following formula: C△U=I leak *t leak =i1*t ch ; Where: I leak is the self-maintaining leakage current, i1 is the current of the constant current source I1; The self-holding time t is obtained by calculation leak and capacitor replenishment time t ch , the self-holding time t leak and capacitor replenishment time t ch By comparison, the situation where the supercapacitor is in a self-maintaining state is obtained.