A design method and design system of an intelligent electric energy meter with thermal coupling failure rate correction

Abstract

The application discloses a kind of intelligent electric energy meter design method and design system of thermal coupling failure rate correction.The design method includes: the original failure rate is calculated based on component stress method to each functional module, thermal coupling failure rate correction factor is calculated according to the thermal coupling parameter between module and the original failure rate is corrected;The thermal coupling degradation degree of each memory is evaluated through forward coupling path, and the data migration direction is determined, the power consumption change caused by data migration is fed back to thermal coupling failure rate correction factor through reverse coupling path, and recalculated and iteratively converges;According to the modified failure rate sorting, targeted design improvement is carried out, and the optimized design scheme is obtained.The design system includes module division and failure rate calculation unit, thermal coupling correction calculation unit, storage migration decision unit, closed-loop iteration unit and design improvement output unit, and each unit cooperates to form an iterative convergence closed loop, and outputs the optimized design scheme.

Description

Technical Field

[0001] This invention relates to the field of smart energy metering technology, and more specifically, to a design method and system for a smart energy meter with thermal coupling failure rate correction. Background Technology

[0002] In smart meter design, multiple functional modules are integrated on the same printed circuit board, and each module stores user data through non-volatile memories such as EEPROM and Flash. Existing reliability design methods use the component stress method specified in relevant standards, assuming that each module is thermally independent. They do not consider the impact of power module heat generation on the temperature of adjacent module components through PCB heat conduction, nor do they establish a feedback coupling mechanism between reliability prediction results and hardware operation strategies.

[0003] As the design lifespan requirement for smart meters increases to 16 years or even longer, problems such as the predicted failure rate deviation (reaching 12%-18%) caused by inter-module thermal coupling effects and the lack of intelligent migration strategies based on thermal degradation prediction in dual-memory redundant designs are becoming increasingly prominent. Therefore, a method and system are needed that can correct the inter-module thermal coupling effect and couple the correction result with the memory management strategy in a closed loop to ultimately guide design optimization. Summary of the Invention

[0004] This invention aims to provide a design method and system for smart energy meters with thermal coupling failure rate correction, solving the technical problems in the prior art where the thermal coupling effect between modules is ignored, the reliability prediction lacks feedback coupling with hardware operation, and the dual memory lacks intelligent migration strategy.

[0005] A first aspect of the present invention provides a design method for a smart energy meter with thermal coupling failure rate correction, comprising: The circuit of the smart energy meter is divided into multiple functional modules according to function. The original failure rate of each functional module is calculated based on the component stress method. The thermal coupling parameters between each functional module are obtained, the thermal coupling failure rate correction factor between each functional module is calculated, and the original failure rate of each functional module is corrected according to the thermal coupling failure rate correction factor to obtain the corrected failure rate of each functional module. The storage module among the multiple functional modules includes a first memory and a second memory respectively arranged at different distances from the heat source. The first memory and the second memory have different erase / write lifetime characteristics. Through a forward coupling path, based on the corrected failure rate and the cumulative erase / write cycles of the first memory and the second memory, the thermal coupling degradation degree of each is evaluated and the data migration direction is determined. Through a reverse coupling path, the power consumption change of the storage module caused by data migration is fed back to the thermal coupling failure rate correction factor for recalculation, iterating until the overall system failure rate correction converges. Based on the ranking of failure rates of each functional module, targeted design improvements were made to obtain an optimized electricity meter design scheme.

[0006] Preferably, the thermal coupling failure rate correction factor is calculated as follows: For any two modules in each functional module, the heat-generating module is denoted as heat source module j, and the module affected by its heat conduction is denoted as affected module i. Then, the thermal coupling failure rate correction factor Φ of heat source module j on affected module i is calculated. ij The calculation formula is: Φ ij =1+κ ij ·(P j / P j,rated )·e (η ij ·d ij / d 0 ) ·(T j,surf T ref ) / ΔT norm ; In the formula, κ ij P is the thermal coupling coefficient between the affected module i and the heat source module j. j P represents the actual power consumption of heat source module j. j,rated η is the rated power consumption of heat source module j. ij Let d be the thermal attenuation coefficient between affected module i and heat source module j. ij Let d0 be the shortest distance between the heat-sensitive component of affected module i and the main heat source component of heat source module j, and T be the reference distance constant. j,surf T represents the surface temperature of the main heat-generating components in the heat source module j. ref For reference temperature, ΔT norm The normalized temperature difference constant is used. After correction, the corrected failure rate of affected module i is equal to the product of its original failure rate and the thermal coupling failure rate correction factors of all other modules. The total corrected failure rate of the whole machine is equal to the sum of the corrected failure rates of each functional module.

[0007] Preferably, in the forward coupling path, thermal coupling degradation acceleration factors for the first memory and the second memory are calculated respectively to determine the data migration direction; the calculation formulas for the thermal coupling degradation acceleration factors G1 and G2 of the first memory and the second memory are as follows: G1=Φ1·(N 1,used / N 1,max ) β ; G2=Φ2·(N 2,used / N 2,max ) β ; In the formula, Φ1 is the thermal coupling failure rate correction factor calculated when the power supply module is the heat source module and the functional module containing the first memory is the affected module, Φ2 is the thermal coupling failure rate correction factor calculated when the power supply module is the heat source module and the functional module containing the second memory is the affected module, and N 1,used N represents the cumulative number of erase / write cycles for the first memory. 1,max N represents the nominal maximum number of erase / write cycles for the first memory. 2,used N represents the cumulative number of erase / write cycles for the second memory. 2,max G1 represents the nominal maximum number of erase / write cycles for the second memory, and β is the degradation acceleration exponent. When G1 > G2, high-frequency erase / write data is migrated from the first memory to the second memory.

[0008] Preferably, in the reverse coupling path, after data migration, the power consumption of the first memory and the second memory are updated according to the following model: Memory power consumption = standby power consumption + power consumption per erase / write cycle × erase / write frequency × duration of per erase / write cycle; The updated power consumption is substituted into the thermal coupling failure rate correction factor for recalculation; the convergence criterion for the iteration is that the absolute value of the difference between the total corrected failure rates of the whole machine in two adjacent iterations is less than the convergence threshold ε.

[0009] Preferably, the thermal coupling coefficient is obtained by applying a heating element of known power to the main heat source location of one module on a blank printed circuit board, measuring the temperature rise at the location of another module using an infrared thermal imager, and calculating the thermal coupling coefficient accordingly.

[0010] Preferably, the targeted design improvements include at least one of the following: arranging temperature-sensitive devices away from heat-generating devices, high-temperature baking of printed circuit boards, use of halogen-free soldering materials, full-board conformal coating, replacing connector connections between current transformers and relays and terminals with soldering processes, and high-temperature aging of the entire machine for easy operation.

[0011] A second aspect of the present invention provides a design system for a smart energy meter with thermal coupling failure rate correction, comprising: At least one processor and a memory, wherein the memory stores a computer program, and the processor, when executing the computer program, implements the following functional units: The module division and failure rate calculation unit is used to divide the circuit of the smart energy meter into multiple functional modules according to their functions, and calculate the original failure rate of each functional module based on the component stress method. The thermal coupling correction calculation unit is used to calculate the thermal coupling failure rate correction factor between each functional module based on the thermal coupling parameters between each functional module, and to correct the original failure rate of each functional module based on the thermal coupling failure rate correction factor to obtain the corrected failure rate of each functional module. The storage migration decision unit is used to evaluate the thermal coupling degradation degree of the first memory and the second memory and determine the data migration direction by using a forward coupling path, based on the correction failure rate and the cumulative erase / write counts of the first memory and the second memory in the smart energy meter; A closed-loop iterative unit is used to feed back the power consumption changes of the storage module caused by data migration to the thermally coupled correction calculation unit for recalculation via a reverse coupling path, iterating until the overall system failure rate converges; and The design improvement output unit is used to generate targeted design improvement schemes based on the sorting results of the failure rates of each functional module.

[0012] Among them, the thermal coupling parameters include the thermal coupling coefficient between each functional module, the ratio of the power consumption of the heat source module to the rated power consumption, the exponential decay characteristics of the distance between modules, and the temperature gradient of the heat source surface.

[0013] Preferably, the storage migration decision unit is configured to make migration decisions for the following memory configurations: the first memory is an EEPROM, the second memory is a Flash memory; the nominal number of erase / write cycles of the first memory is greater than the nominal number of erase / write cycles of the second memory, and the distance between the first memory and the heat source of the power module of the object being designed is less than the distance between the second memory and the heat source of the power module of the object being designed.

[0014] Preferably, the design improvement scheme generated by the design improvement output unit includes a pluggable modular design for the communication module, so that replacing the communication module does not affect the metering data and parameters inside the energy meter.

[0015] Preferably, the thermal coupling correction calculation unit is configured to calculate the thermal coupling failure rate correction factor based on the thermal coupling coefficient between each functional module, the ratio of the power consumption of the heat source module to the rated power consumption, the exponential decay characteristic of the distance between modules, and the temperature gradient of the heat source surface; the storage migration decision unit is configured to calculate the thermal coupling degradation acceleration factor based on the ratio of the thermal coupling failure rate correction factor of the power module to the respective locations of the first memory and the second memory to the ratio of their respective cumulative erase / write counts to the nominal maximum erase / write counts, and determine the data migration direction accordingly; in the reverse coupling path, the closed-loop iteration unit is configured to update the power consumption of the first memory and the second memory respectively based on the erase / write frequency changes caused by data migration, and feed the updated power consumption back to the thermal coupling correction calculation unit until the overall machine correction failure rate converges.

[0016] This invention is the first to introduce quantitative correction of inter-module thermal interaction effects in the reliability design of energy meters and establish a closed-loop mechanism for forward and reverse coupling paths, which significantly improves the effective lifespan of the storage modules, exceeding the simple sum of the effects of thermal coupling failure rate correction and dynamic migration implemented individually. The predicted failure rate of the whole machine after thermal coupling correction more accurately reflects the actual reliability level, providing a quantitative basis for targeted design improvements. After the improvement, the reliable lifespan can reach more than 32 years at 90% reliability. Attached Figure Description

[0017] Exemplary embodiments of the present invention can be more fully understood by referring to the following figures: Figure 1 This is a flowchart illustrating the design method of the present invention; Figure 2 This is a schematic diagram of the structure of the smart energy meter design system of the present invention; Figure 3 This is a schematic diagram of the module layout of the printed circuit board of the smart energy meter, the object of this invention. Figure 4 This is a schematic diagram of the closed-loop iterative convergence process of the present invention; Figure 5 This is a reliability comparison curve between conventional prediction and thermal coupling correction. Detailed Implementation

[0018] Exemplary embodiments of the invention will now be described with reference to the accompanying drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the drawings is not intended to limit the invention.

[0019] Exemplary methods Figure 1 This is a flowchart illustrating a design method for a smart energy meter with thermal coupling failure rate correction, provided by an exemplary embodiment of the present invention. This embodiment can be applied to the reliability design stage of single-board integrated smart energy meters, such as... Figure 1 As shown, it includes the following steps: Step S1: Divide the circuit of the smart energy meter into modules according to function and mark the physical location of each module on the printed circuit board.

[0020] Specifically, the smart energy meter circuit is divided into six functional modules: a power supply module, a metering module, a control module, a display module, a storage module, and a communication module. The power supply module includes a transformer, a DC-DC converter chip, and a three-terminal voltage regulator to provide multiple stable DC power sources. The metering module includes a metering chip and a current transformer. The control module includes a microcontroller and a security encryption chip. The display module includes an LCD screen. The storage module includes a first memory and a second memory, which have different erase / write lifespan characteristics and capacities, and are respectively arranged on the printed circuit board at different distances from the heat source of the power supply module. The communication module includes a communication chip and a communication interface. The circuits of the six functional modules are integrated on the same printed circuit board. The layout of the six functional modules on the printed circuit board is as follows: Figure 3 As shown, the first memory U5 is about 18mm away from the power module transformer T1, and the second memory U8 is about 35mm away from the transformer T1.

[0021] Step S2: Calculate the original failure rate of each module based on the component stress method.

[0022] Specifically, based on relevant standards for predicting the reliability of electricity metering equipment, a component failure rate prediction model is established. This model calculates the operational failure rate as the product of the reference failure rate and various correction coefficients, and then calculates and sums the operational failure rates of all components within each module. In one embodiment, the original failure rates of each module are as follows: power supply module 58.59 FIT, metering module 55.16 FIT, control module 102.50 FIT, display module 3.12 FIT, storage module 57.97 FIT, and communication module 41.53 FIT, totaling 318.87 FIT.

[0023] Step S3: Obtain the thermal coupling parameters between each module.

[0024] Specifically, the thermal coupling coefficient κ between each module is obtained through thermal simulation or actual measurement. ij Thermal attenuation coefficient η ij , Module distance d ij and the surface temperature T of each module's heat source j,surf .

[0025] In one embodiment, the thermal coupling coefficient κ ijThe temperature rise ΔT at module i is determined by applying a heating element of known power to the main heat source location of module j on a blank printed circuit board, and measuring the temperature rise ΔT using an infrared thermal imager. i κ is calculated based on this. ij =ΔT i ·ΔT norm / (P j ·(T j,surf T ref )).

[0026] In one embodiment, the printed circuit board reference number of the first memory is U5, and the printed circuit board reference number of the second memory is U8. The measured values ​​of the thermal coupling parameters between the modules are shown in the table below: It should be noted that the above parameter values ​​can be adjusted according to the actual printed circuit board structure and component layout, and are not specifically limited here.

[0027] Step S4: Calculate the thermal coupling failure rate correction factor between each module based on the thermal coupling parameters obtained in step S3, and correct the original failure rate of each module.

[0028] Specifically, for any two modules in each functional module, the heat-generating module is denoted as heat source module j, and the module affected by its heat conduction is denoted as affected module i. The formula for calculating the thermal coupling failure rate correction factor Φij of heat source module j to affected module i is: Φ ij =1+κ ij ·(P j / P j,rated )·e (ηij·dij / d0) ·(T j,surf T ref ) / ΔT norm ; Where: Φ ij κ is a dimensionless correction factor for the thermal coupling failure rate of heat source module j to affected module i, ≥1; ij P represents the thermal coupling coefficient between the affected module i and the heat source module j, with a value ranging from 0.01 to 0.15. j P represents the actual power consumption of heat source module j. j,rated η is the rated power consumption of heat source module j; ij The thermal attenuation coefficient between the affected module i and the heat source module j is taken as 0.03–0.12 mm. 1 ;d ijd0 is the shortest distance between the heat-sensitive component of affected module i and the main heat source component of heat source module j, and is taken as 10mm; T j,surf T represents the surface temperature of the main heat-generating components in the heat source module j. ref Take 25℃; ΔT norm Set the temperature to 30℃.

[0029] In this formula, the exponential decay term reflects the exponential decay of the thermal coupling effect with distance, which conforms to the approximate solution of Fourier's law of heat conduction on a finite board; the power consumption ratio term reflects the actual heat output intensity of the heat source module; and the temperature gradient term normalizes the absolute temperature influence of the heat source. The product form of the four physical quantities ensures the superposition and amplification effect when all influencing factors exist simultaneously, reflecting the nonlinear influence of thermal stress on the reliability of components.

[0030] In one embodiment, the thermal coupling failure rate correction factor of the first memory (18mm from the transformer) is calculated using the power module (transformer rated load 3.2W, surface temperature 58°C) as an example: Φ U5,power =1+0.08×(3.2 / 3.2)×e (0.06×18 / 10) ×(58 25) / 30 = 1 + 0.08 × 1.0 × 0.898 × ​​1.100 = 1 + 0.079 = 1.079; The thermal coupling failure rate correction factor of the power module to the second memory (35mm from the transformer) is only 1.045, and the difference comes from the distance term: e (0.06×35 / 10) =0.811 is less than e (0.06×18 / 10) =0.898. This indicates that the first memory, being closer to the transformer, is more affected by thermal coupling than the second memory.

[0031] After correction, the corrected failure rate of the affected module is equal to the product of its original failure rate and the correction factors for the thermal coupling failure rates of all other modules. The overall corrected failure rate is equal to the sum of the corrected failure rates of each functional module.

[0032] Step S5: Using the forward coupling path, based on the corrected failure rate and the cumulative number of erase / write cycles of each memory, assess the degree of thermal coupling degradation of each memory and determine the data migration direction.

[0033] Specifically, the thermal coupling degradation acceleration factors of the first memory and the second memory are calculated respectively to determine the data migration direction. The formula for calculating the thermal coupling degradation acceleration factor G1 of the first memory is as follows: G1=Φ1·(N 1,used / N 1,max )β ; G2=Φ2·(N 2,used / N 2,max ) β ; In the formula, Φ1 is the thermal coupling failure rate correction factor calculated when the power supply module is the heat source module and the functional module containing the first memory is the affected module, Φ2 is the thermal coupling failure rate correction factor calculated when the power supply module is the heat source module and the functional module containing the second memory is the affected module, and N 1,used N represents the cumulative number of erase / write cycles for the first memory. 1,max N represents the nominal maximum number of erase / write cycles for the first memory. 2,used N represents the cumulative number of erase / write cycles for the second memory. 2,max G1 represents the nominal maximum number of erase / write cycles for the second memory, and β is the degradation acceleration index, ranging from 0.5 to 1.5. In this embodiment, the same degradation acceleration index β is used for both types of memory to simplify calculation. In other embodiments, different degradation acceleration indices can be set according to different memory types. When G1 > G2, high-frequency erase / write data (such as real-time cumulative power consumption and rate data) is migrated from the first memory to the second memory, while low-frequency read data (such as event logs and historical frozen data) is retained in the first memory.

[0034] In one embodiment, it is assumed that after 10 years of operation, the first memory (EEPROM, nominally capable of 4 million erase / write cycles) has been erased / written 2 million times, and the second memory (Flash, nominally capable of 100,000 erase / write cycles) has been erased / written 30,000 times. Let β = 1.0. G1 = 1.079 × (2000000 / 4000000) 1.0 =0.540; G2 = 1.045 × (30000 / 100000) 1.0 =0.314; Since G1 > G2, it is determined that the thermal coupling degradation of the first memory is higher than that of the second memory, triggering data migration.

[0035] Step S6: Through the reverse coupling path, the power consumption change of the storage module caused by data migration is fed back to the thermal coupling failure rate correction factor for recalculation, and the process is iterated until the overall machine correction failure rate converges.

[0036] Specifically, after data migration, the erase and write frequencies of the first and second memories change, resulting in changes in their power consumption. Taking the first memory as an example, its power consumption is updated according to the following model: P storage,1 =P standby,1 +P write,1 ·fwrite,1 ·t write,1 ; The power consumption update model for the second memory has the same structure as the above formula, except that the subscript is replaced by '2' instead of '1'.

[0037] Where P standby,1 P represents the standby power consumption of the first memory. write,1 For the power consumption of a single erase / write cycle, f write,1 t is the erase / write frequency. write,1 This represents the duration of a single erase / write operation; the parameters of the second memory have the same meaning, only the subscript is changed from '1' to '2'. Changes in the power consumption of the memory module will alter its thermal contribution to adjacent modules, thus affecting the calculation result of the thermal coupling failure rate correction factor, forming a closed-loop feedback. The convergence criterion is |λ' s (n+1) λ' s (n) |<ε, where ε is set to 0.1 FIT. Since the change in memory power consumption is much smaller than that of the power supply module, this closed loop typically converges after 2 to 4 iterations.

[0038] In one embodiment, after data migration, the erase / write frequency of the second memory increases from approximately 300 times / day to approximately 800 times / day, while that of the first memory decreases to approximately 100 times / day. The power consumption of the second memory increases from 0.8mW to 1.2mW, while that of the first memory decreases to 0.5mW.

[0039] First iteration: λ' s (1) =367.26 FIT. Second iteration: λ' s (2) =367.08 FIT, |0.18|>0.1, continue. Third iteration: λ' s ( ³ ) =367.02 FIT, |0.06|<0.1, convergence. The final overall error correction rate is 367 FIT, which is about 15.1% higher than the traditional method's 318.87 FIT. The iterative convergence process is as follows: Figure 4 As shown, the overall failure rate of the whole machine converges to 367 FIT after 3 iterations.

[0040] It should be noted that the above values ​​are merely illustrative. The specific number of iterations and convergence results depend on the actual module layout and component parameters of the electricity meter, and are not specifically limited here.

[0041] Step S7: Based on the ranking results of the failure rates of each module, targeted design improvements are made to obtain an optimized electricity meter design scheme.

[0042] Specifically, the targeted design improvements include at least one of the following: arranging temperature-sensitive devices away from heat-generating devices, high-temperature baking of printed circuit boards, use of halogen-free soldering materials, full-board conformal coating, replacing connector connections between current transformers and relays and terminals with soldering processes, and high-temperature aging of the entire machine.

[0043] In one embodiment, the functional modules are ordered from highest to lowest corrected failure rate as follows: control module, power module, storage module, metering module, communication module, and display module. For the control module and power module, which have the highest corrected failure rate, measures are taken to keep temperature-sensitive devices away from heat-generating components. Specifically, the distance between the security encryption chip in the control module and the transformer in the power module is increased from the original design, thus reducing the corresponding thermal coupling failure rate correction factor. For the storage module and metering module, a 120°C high-temperature baking method is used on the printed circuit board to eliminate residual moisture and residual stress, reducing the risk of solder joint fatigue failure caused by the superposition of residual stress and thermal coupling effects. For the current transformer in the metering module and the relay in the control module, soldering technology is used instead of connector connections to reduce localized heating caused by contact resistance. At the overall machine level, halogen-free high-specification solder paste is used for production soldering, full-board conformal coating is applied to improve resistance to damp heat and corrosion, and high-temperature aging is performed on the entire machine to screen out early-failure components.

[0044] Furthermore, the communication module can adopt a pluggable modular design, supporting hot-swappable interchange of multiple communication methods. Replacing the communication module will not affect the metering data and parameters inside the electricity meter.

[0045] To verify the effectiveness of the above method, the mean time between failures (MTBF) and reliable life can be calculated further based on the total failure rate of the converged whole machine.

[0046] In one embodiment, the reliability corresponding to each reliable lifetime after correction is shown in the following table: The revised 16-year reliability is 0.94986 (close to 95%), and the 32-year reliability is 0.90224 (>90%). The revised reliability indicators more accurately reflect the actual reliability level of the product.

[0047] The reliability comparison curves of conventional prediction and thermal coupling correction are as follows: Figure 5 As shown, the revised 16-year reliability decreased from the traditionally expected 0.95629 to 0.94986, more accurately reflecting the actual reliability level of the product.

[0048] Implementing thermal coupling failure rate correction alone can only yield more accurate failure rate predictions; implementing dual-memory dynamic migration alone can only balance based on erase / write cycles. By coupling the two through forward and reverse coupling paths, thermal coupling failure rate correction provides differentiated thermal stress information, enabling the migration strategy to perceive the physical location environment of the memory. Simultaneously, the migration strategy adjustment redistributes power consumption, and the system automatically finds the optimal balance point. Experimental data shows that this coupling design significantly improves the effective lifetime of the memory modules, exceeding the sum of the effects of the two individual measures, demonstrating the nonlinear gain effect generated by the synergistic work of the forward and reverse coupling paths.

[0049] Exemplary Design System Figure 2 This is a schematic diagram of the design system for a smart energy meter with thermal coupling failure rate correction, provided by an exemplary embodiment of the present invention. The design system runs on a computing device equipped with a processor and memory, wherein the memory stores computer programs implementing each functional unit, such as... Figure 2 As shown, the design system includes a module partitioning and failure rate calculation unit, a thermal coupling correction calculation unit, a storage migration decision unit, a closed-loop iteration unit, and a design improvement output unit.

[0050] The design system is designed for a single-board integrated smart energy meter. This smart energy meter includes six functional modules integrated on the same printed circuit board: a power supply module, a metering module, a control module, a display module, a storage module, and a communication module. The power supply module includes a transformer, a DC-DC converter chip, and a three-terminal regulator; the metering module includes a metering chip and a current transformer; the control module includes a microcontroller and a security encryption chip; the display module includes an LCD screen; the storage module includes a first memory and a second memory, which have different erase / write lifespan characteristics and capacities, and are respectively arranged on the printed circuit board at different distances from the heat source of the power supply module; the communication module includes a communication chip and a communication interface. The design system uses the circuit design parameters and printed circuit board layout parameters of the aforementioned smart energy meter as input to perform calculations for the following functional units: The module partitioning and failure rate calculation unit receives the circuit design parameters of the smart energy meter and divides the circuit into multiple functional modules such as a power supply module, metering module, control module, display module, storage module, and communication module. It then calculates the original failure rate of each functional module based on the component stress method. The thermal coupling correction calculation unit calculates the thermal coupling failure rate correction factor between each module based on thermal coupling parameters such as the thermal coupling coefficient between functional modules, the power consumption state of the heat source module, the distance between modules, and the surface temperature of the heat source. Based on this, it corrects the original failure rate of each functional module to obtain the corrected failure rate. The storage migration decision unit, through a forward coupling path, evaluates the degree of thermal coupling degradation of the first and second memories in the smart energy meter and determines the data migration direction based on the corrected failure rate and the cumulative erase / write counts of each. The closed-loop iteration unit, through a reverse coupling path, feeds back the power consumption change of the storage module caused by data migration to the thermal coupling correction calculation unit to recalculate the correction factor, iterating until the overall corrected failure rate converges. The design improvement output unit generates a targeted design improvement scheme, including layout optimization of temperature-sensitive devices and process improvement measures, based on the sorting results of the failure rates of each functional module.

[0051] In one embodiment, the system is designed for a single-board integrated smart meter, whose storage module includes a first memory (EEPROM, e.g., but not limited to a capacity of 512K and a nominal write cycle of 4 million) and a second memory (Flash memory, e.g., but not limited to a capacity of 4M and a nominal write cycle of 100,000). The distance between the first memory and the power module transformer is, for example, but not limited to, 18mm, and the distance between the second memory and the transformer is, for example, but not limited to, 35mm. The storage migration decision unit uses the difference in thermal coupling failure rate correction factor caused by this distance difference to assess the degree of differential degradation.

[0052] The reliability design system of this invention corresponds to the design method of another embodiment of this invention. Each functional unit of the design system performs the calculation and decision-making functions of the corresponding steps in the design method.

[0053] To verify the effectiveness of the design method of the present invention, a reliability prediction verification and a full performance test verification were carried out on a single-phase prepaid smart energy meter (rated voltage 220V, current range 0.25-0.5(60)A, 50Hz, active power class A) designed using the method of the present invention.

[0054] In the reliability prediction verification, the overall failure rate was first calculated to be 318.87 FIT using the traditional component stress method (without thermal coupling correction), corresponding to a reliable lifespan of 18 years at 95% reliability and 37 years at 90% reliability. Subsequently, thermal coupling failure rate correction and closed-loop iterative calculation were performed according to the methods described in steps S4 to S6 of this invention. After three iterations and convergence, the corrected total failure rate of the entire machine was obtained as 367 FIT, corresponding to a reliable lifespan of 16 years at 95% reliability and 32 years at 90% reliability. The comparison of the two sets of data shows that the traditional method underestimates the failure rate by approximately 15.1% due to neglecting the thermal coupling effect between modules, verifying the necessity of introducing the thermal coupling failure rate correction factor in this invention. Furthermore, the corrected lifespan still meets the requirement of over 32 years at 90% reliability. After implementing the targeted design improvements described in step S7, the design lifespan at 95% reliability can meet the requirement of over 16 years, indicating that the energy meter optimized by the method of this invention possesses a reliability level that meets actual operational needs.

[0055] In the full-performance test verification, 10 samples designed according to the method of the present invention and implemented with the targeted design improvement measures described in step S7 were selected. A total of 77 full-performance tests covering aspects such as metrological accuracy, environmental adaptability, electromagnetic compatibility, mechanical strength, safety performance and functional integrity were conducted in accordance with relevant industry technical specifications, and all of them passed.

[0056] The experimental results closely related to the thermal coupling design of this invention include: In the initial inherent error test, the actual errors at each current point with power factors of 1.0, 0.5L, and 0.8C were all between 0.0% and -0.1%, far less than the allowable error, indicating that the thermal coupling effect between modules did not have an observable impact on the metering accuracy. In the ambient temperature change test, the energy meter was tested in six temperature ranges from -25℃ to +55℃, and the actual temperature coefficient of each temperature range was 0.00% / K, verifying the effectiveness of the placement measure of keeping the temperature-sensitive device away from the heat-generating device in step S7 of this invention. In the high-temperature test, after the energy meter was continuously operated in an environment of +70℃ for 72 hours, the metering error deviation was only +0.01%; in the low-temperature test, after the energy meter was continuously operated in an environment of -40℃ for 72 hours, the error deviation was only -0.01%, verifying the stability of the design scheme after thermal coupling correction and closed-loop optimization of this invention under extreme temperature conditions. In the self-heating test, after the energy meter operated continuously under full load current until the temperature stabilized, the actual error deviation was only +0.01% (power factor 1.0), indicating that the metering accuracy remained stable under the condition of high current self-heating, which indirectly verified the predictive ability of the thermal coupling failure rate correction factor for the heating condition.

[0057] Furthermore, in the communication module interchangeability test, after hot-swapping the communication module of the energy meter, the metering data and parameters stored in the meter remained unaffected, verifying the technical effectiveness of the pluggable communication module design. In the power consumption test, the measured power consumption of the entire unit in communication mode was 1.00W, and the power consumption of the voltage line in non-communication mode was 0.36W, both far below the allowable values, indicating good overall power consumption control. This provides measured support for the accuracy of the power consumption ratio term in the thermal coupling failure rate correction factor of this invention.

[0058] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0059] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For system embodiments, since they largely correspond to method embodiments, the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

Claims

1. A design method for a smart energy meter with thermal coupling failure rate correction, characterized in that, include: The circuit of the smart energy meter is divided into multiple functional modules according to function, and the original failure rate of each functional module is calculated based on the component stress method. The thermal coupling parameters between each functional module are obtained, the thermal coupling failure rate correction factor between each functional module is calculated, and the original failure rate of each functional module is corrected according to the thermal coupling failure rate correction factor to obtain the corrected failure rate of each functional module. The storage module among the multiple functional modules includes a first memory and a second memory respectively arranged at different distances from the heat source. The first memory and the second memory have different erase and write lifetime characteristics. Through the forward coupling path, based on the corrected failure rate and the cumulative erase and write counts of the first memory and the second memory, the thermal coupling degradation degree of the first memory and the second memory is evaluated and the data migration direction is determined. Through the reverse coupling path, the power consumption change of the storage module caused by data migration is fed back to the thermal coupling failure rate correction factor for recalculation, and iterated until the overall machine correction failure rate converges. as well as Based on the ranking of the failure rates of each functional module, targeted design improvements were made to obtain an optimized electricity meter design scheme. The first memory is an EEPROM, and the second memory is a Flash memory; The nominal number of erase / write cycles of the first memory is greater than that of the second memory, and the distance between the first memory and the heat source of the power module of the designed object is less than that between the second memory and the heat source of the power module of the designed object. It also includes calculating the thermal coupling failure rate correction factor based on the thermal coupling coefficient between each functional module, the ratio of the power consumption of the heat source module to the rated power consumption, the exponential decay characteristics of the distance between modules, and the temperature gradient of the heat source surface. The thermal coupling degradation acceleration factor is calculated based on the ratio of the thermal coupling failure rate correction factor of the power module to the ratio of the cumulative number of erase / write operations to the nominal maximum number of erase / write operations, and the data migration direction is determined accordingly. In the reverse coupling path, the power consumption of the first memory and the second memory is updated according to the change in erase / write frequency caused by data migration, and the updated power consumption is fed back until the overall failure rate of the whole machine converges.

2. The design method for a smart energy meter with thermal coupling failure rate correction according to claim 1, characterized in that, The calculation method for the thermal coupling failure rate correction factor is as follows: For any two modules in each functional module, the heat-generating module is denoted as heat source module j, and the module affected by its heat conduction is denoted as affected module i. Then, the thermal coupling failure rate correction factor Φ of heat source module j on affected module i is... ij The calculation formula is: Φ ij =1+κ ij ·(P j / P j,rated )·e (η ij ·d ij / d 0 ) ·(T j,surf T ref ) / ΔT norm ; In the formula, κ ij P is the thermal coupling coefficient between the affected module i and the heat source module j. j P represents the actual power consumption of heat source module j. j,rated η is the rated power consumption of heat source module j. ij Let d be the thermal attenuation coefficient between affected module i and heat source module j. ij Let d0 be the shortest distance between the heat-sensitive component of affected module i and the main heat source component of heat source module j, and T be the reference distance constant. j,surf T represents the surface temperature of the main heat-generating components in the heat source module j. ref For reference temperature, ΔT norm This is the normalized temperature difference constant; After correction, the corrected failure rate of affected module i is equal to the product of its original failure rate and the thermal coupling failure rate correction factors of all other modules. The total corrected failure rate of the whole machine is equal to the sum of the corrected failure rates of each functional module.

3. The design method for a smart energy meter with thermal coupling failure rate correction according to claim 2, characterized in that, In the forward coupling path, thermal coupling degradation acceleration factors for the first memory and the second memory are calculated respectively to determine the data migration direction; the calculation formulas for the thermal coupling degradation acceleration factors G1 and G2 of the first memory and the second memory are as follows: G1=Φ1·(N 1,used / N 1,max ) β ; G2=Φ2·(N 2,used / N 2,max ) β ; In the formula, This is the thermal coupling failure rate correction factor calculated when the power supply module is the heat source module and the functional module containing the first memory is the affected module. N is the thermal coupling failure rate correction factor calculated when the power supply module is the heat source module and the functional module containing the second memory is the affected module. 1,used N represents the cumulative number of erase / write cycles for the first memory. 1,max N represents the nominal maximum number of erase / write cycles for the first memory. 2,used N represents the cumulative number of erase / write cycles for the second memory. 2,max β is the nominal maximum number of erase / write cycles for the second memory, and β is the degradation acceleration exponent. When G1 > G2, high-frequency erase / write data is migrated from the first memory to the second memory.

4. The design method for a smart energy meter with thermal coupling failure rate correction according to claim 3, characterized in that, In the reverse coupling path, after data migration, the power consumption of the first memory and the second memory are updated according to the following model: Memory power consumption = standby power consumption + power consumption per erase / write cycle × erase / write frequency × duration of per erase / write cycle; The updated power consumption is substituted into the thermal coupling failure rate correction factor for recalculation; the convergence criterion for the iteration is that the absolute value of the difference between the total corrected failure rates of the whole machine in two adjacent iterations is less than the convergence threshold ε.

5. The design method for a smart energy meter with thermal coupling failure rate correction according to claim 2, characterized in that, The thermal coupling coefficient is obtained by applying a heating element of known power to the main heat source location of one module on a blank printed circuit board, measuring the temperature rise at the location of another module using an infrared thermal imager, and calculating the thermal coupling coefficient accordingly.

6. The design method for a smart energy meter with thermal coupling failure rate correction according to claim 1, characterized in that, The targeted design improvements include at least one of the following: placing temperature-sensitive devices away from heat-generating devices, high-temperature baking of printed circuit boards, halogen-free soldering materials, full-board conformal coating, replacing connector connections between current transformers and relays and terminals with soldering processes, and high-temperature aging of the entire machine.

7. A design system for a smart energy meter with thermal coupling failure rate correction, characterized in that, include: At least one processor and a memory, wherein the memory stores a computer program, and the processor, when executing the computer program, implements the following functional units: The module division and failure rate calculation unit is used to divide the circuit of the smart energy meter into multiple functional modules according to their functions, and calculate the original failure rate of each functional module based on the component stress method. The thermal coupling correction calculation unit is used to calculate the thermal coupling failure rate correction factor between each functional module based on the thermal coupling parameters between each functional module, and to correct the original failure rate of each functional module based on the thermal coupling failure rate correction factor to obtain the corrected failure rate of each functional module. The storage migration decision unit is used to evaluate the thermal coupling degradation degree of the first memory and the second memory and determine the data migration direction by using a forward coupling path, based on the correction failure rate and the cumulative erase / write counts of the first memory and the second memory in the smart energy meter; The closed-loop iterative unit is used to feed back the power consumption change of the storage module caused by data migration to the thermally coupled correction calculation unit for recalculation through the reverse coupling path, and iterate until the overall system correction failure rate converges. as well as The design improvement output unit is used to generate targeted design improvement schemes based on the ranking results of the failure rates of each functional module. The storage migration decision unit is configured to make migration decisions for the following memory configurations: the first memory is an EEPROM, and the second memory is a Flash memory; The nominal number of erase / write cycles of the first memory is greater than that of the second memory, and the distance between the first memory and the heat source of the power module of the designed object is less than that between the second memory and the heat source of the power module of the designed object. The thermal coupling correction calculation unit is configured to calculate the thermal coupling failure rate correction factor based on the thermal coupling coefficient between each functional module, the ratio of the power consumption of the heat source module to the rated power consumption, the exponential decay characteristics of the distance between modules, and the temperature gradient of the heat source surface. The storage migration decision unit is configured to calculate the thermal coupling degradation acceleration factor based on the ratio of the thermal coupling failure rate correction factor of the power module to the respective locations of the first memory and the second memory to the ratio of the cumulative number of erase / write operations to the nominal maximum number of erase / write operations, and determine the data migration direction accordingly. In the reverse coupling path, the closed-loop iterative unit is configured to update the power consumption of the first memory and the second memory respectively according to the erase / write frequency changes caused by data migration, and feed the updated power consumption back to the thermally coupled correction calculation unit until the overall machine correction failure rate converges.

8. The design system for a smart energy meter with thermal coupling failure rate correction according to claim 7, characterized in that, The design improvement scheme generated by the design improvement output unit includes a pluggable modular design for the communication module, so that replacing the communication module does not affect the metering data and parameters inside the energy meter.

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