Intelligent electric meter power-off storage circuit and method

Abstract

The application relates to the technical field of intelligent electric meters, and discloses a power-off saving circuit and method of an intelligent electric meter, which comprises a strong-power power-off detection circuit, a weak-power power-off detection circuit, a power-off power supply circuit and a controller. The power-off power supply circuit comprises a super capacitor and a power supply battery. The controller performs electric meter data power-off saving after detecting strong-power power-off, and when the time interval between the occurrence of strong-power power-off and the occurrence of weak-power power-off is greater than or equal to a preset time length, the weak-power power-off detection circuit capacitor, the super capacitor and the power supply battery are sequentially used for power supply, and electric meter data power-off saving is performed again. The application reduces the use frequency of the power supply battery, reduces the loss of the power supply battery, adopts a double power-off judgment mode to perform power-off data saving, can perform different power-off data saving after normal power-off and voltage sag, and improves the reliability of power-off data saving.

Description

Technical Field

[0001] This invention relates to the field of smart meter technology, and specifically to a smart meter power-off retention circuit and method. Background Technology

[0002] With the increasing prevalence of smart meters, their functions are becoming more complex. They need to retain more data during power outages, placing higher demands on the meter's power circuitry. Simultaneously, with societal development and rising electricity consumption, data loss or errors during power outages can lead to disputes between customers and power companies. Currently, most meters rely on batteries for data retention during power outages. If the battery experiences a voltage drop due to abnormal conditions, data loss or errors are highly likely during a power outage.

[0003] Currently, smart meters rely solely on battery power for data retention during power outages. However, battery wear is significant, which can lead to errors in data retention during power outages, resulting in low reliability of data retention. Summary of the Invention

[0004] In view of this, the present invention provides a circuit and method for power-off data retention in smart meters to solve the technical problem of low reliability of power-off data retention in smart meters.

[0005] In a first aspect, the present invention provides a power-off retention circuit for a smart meter, comprising:

[0006] A high-voltage power failure detection circuit is used to detect the three-phase power input and output a high-voltage indication signal to the controller based on the three-phase power input. The controller determines whether a high-voltage power failure has occurred based on the high-voltage indication signal.

[0007] A low-voltage power failure detection circuit is used to detect the low-voltage signal of the low-voltage power supply and send the low-voltage signal to the controller. The controller determines whether a low-voltage power failure has occurred based on the low-voltage signal.

[0008] The power-off power supply circuit, including a supercapacitor and a power supply battery, is used to power the controller and the power-off preservation circuit.

[0009] The controller is used to save power failure data after detecting a power failure. When the time interval between the occurrence of a power failure and a weak power failure is greater than or equal to a preset duration, it calculates the energy required for saving the power failure data based on the current operating state. Based on the energy required for saving the power failure data, it sequentially uses the capacitor in the weak power failure detection circuit, the supercapacitor in the power failure power supply circuit, and the power supply battery to supply power to the controller and the power failure saving circuit to save the meter data. When the time interval between the occurrence of a power failure and a weak power failure is less than the preset duration, it does not save the meter data after saving the power failure data.

[0010] In some optional embodiments, the high-voltage power failure detection circuit includes a metering chip. The input terminal of the metering chip is connected to the three-phase power input, and the output terminal of the metering chip is connected to the first signal detection terminal of the controller. When all three phase voltages of the three-phase power input are less than the first detection threshold, the high-voltage indication signal output by the metering chip is low. When any phase voltage of the three-phase power input is greater than or equal to the first detection threshold, the high-voltage indication signal output by the metering chip is high. When the high-voltage indication signal detected by the first signal detection terminal of the controller has a falling edge, it is determined that a high-voltage power failure has occurred.

[0011] In some optional embodiments, the low-voltage power failure detection circuit includes a first resistor, a second resistor, and a first capacitor. The first end of the first resistor is connected to the low-voltage power supply and the positive terminal of the first capacitor, respectively. The second end of the first resistor is connected to the first end of the second resistor and the second signal detection terminal of the controller, respectively. The second end of the second resistor is connected to the negative terminal of the first capacitor and grounded. When the low-voltage signal detected by the second signal detection terminal of the controller is less than the second detection threshold, it is determined that a low-voltage power failure has occurred.

[0012] In some optional embodiments, the power failure preservation circuit of the smart meter further includes a first conversion circuit and a second conversion circuit. The first conversion circuit is used to convert the three-phase power input into a low-voltage power supply, and the second conversion circuit is used to convert the low-voltage power supply into a preset power supply.

[0013] In some alternative implementations, the power-down power supply circuit further includes:

[0014] The power-off preservation circuit has its input terminals connected to the output terminal of the second conversion circuit, the supercapacitor, and the power supply battery, respectively, and its output terminals connected to the controller and the power-off preservation circuit, respectively, and is used to supply power to the controller and the power-off preservation circuit using the output of the second conversion circuit, the supercapacitor, and the power supply battery;

[0015] A supercapacitor charging and discharging control circuit includes a charging control circuit and a discharging control circuit. The control terminal of the charging control circuit is connected to the first signal output terminal of the controller and is used to control whether a preset power supply charges the supercapacitor according to the first enable signal output by the controller. The control terminal of the discharging control circuit is connected to the second signal output terminal of the controller and is used to control whether the supercapacitor discharges according to the second enable signal output by the controller and to provide an input voltage for a power-off preservation power supply circuit. The power-off preservation power supply circuit uses the input voltage provided by the supercapacitor to power the controller and the power-off preservation circuit.

[0016] The battery control circuit is connected to the control terminal and the third signal output terminal of the controller. It is used to control whether the power supply battery provides input voltage to the power-down preservation power circuit according to the third enable signal output by the controller. The power-down preservation power circuit uses the input voltage provided by the power supply battery to power the controller and the power-down preservation circuit.

[0017] In some optional embodiments, the supercapacitor charge and discharge control circuit further includes a capacitor charge monitoring circuit, which is connected to the first detection terminal of the supercapacitor and the controller respectively, and the controller detects the energy of the supercapacitor through the capacitor charge monitoring circuit.

[0018] In some alternative implementations, the power supply battery includes a power outage meter reading battery and a clock battery, and the battery control circuit includes a power outage meter reading battery control circuit and a clock battery control circuit.

[0019] The power outage meter reading battery control circuit includes a third resistor, a fourth resistor, and a first low-dropout linear regulator. The first end of the third resistor is connected to the positive terminal of the power outage meter reading battery. The second end of the third resistor is connected to the first end of the fourth resistor and the enable terminal of the first low-dropout linear regulator. The enable terminal of the first low-dropout linear regulator is connected to the fourth signal output terminal of the controller. The second end of the fourth resistor is connected to the negative terminal of the power outage meter reading battery.

[0020] The clock battery control circuit includes a comparator and a MOSFET. The input of the comparator is connected to the output of the first low-dropout linear regulator, and the output of the comparator is connected to the enable terminal of the active switch. The two ends of the active switch are connected to the positive terminal of the clock battery and the input of the power-down retention circuit, respectively.

[0021] In some optional embodiments, the battery control circuit further includes a power outage meter reading battery detection circuit, which includes a fifth resistor and a sixth resistor. The first end of the fifth resistor is connected to the positive terminal of the power outage meter reading battery, and the second end of the fifth resistor is connected to the first end of the sixth resistor and the second detection terminal of the controller.

[0022] In a second aspect, the present invention provides a method for power-off data retention in a smart meter, applied to a power-off data retention circuit of a smart meter as described in any of the first aspects of the present invention, the method comprising:

[0023] It receives high-voltage indication signals and low-voltage signals, and determines whether a high-voltage power failure has occurred based on the high-voltage indication signal and whether a low-voltage power failure has occurred based on the low-voltage signal.

[0024] The meter data is saved after a power outage is detected.

[0025] When the time interval between a high-voltage power failure and a low-voltage power failure is greater than or equal to a preset duration, the energy required for power failure data preservation is calculated based on the current operating status. Based on the energy required for power failure data preservation, the supercapacitor and power supply battery in the power failure power supply circuit are controlled to supply power to the controller and the power failure preservation circuit in sequence, so as to preserve the meter data during power failure.

[0026] If the time interval between a high-voltage power outage and a low-voltage power outage is less than a preset duration, the meter data will not be saved after the high-voltage power outage data has been saved.

[0027] In some optional embodiments, before controlling the supercapacitor and power supply battery in the power-down power supply circuit to supply power to the controller and power-down preservation circuit sequentially according to the energy required for power-down data preservation, the method further includes:

[0028] The energy required for data retention during power failure is determined based on whether the energy of the first capacitor in the low-voltage power failure detection circuit meets the power failure retention requirements. If the energy of the first capacitor meets the power failure retention requirements, the controller and power failure retention circuit are powered through the first capacitor to perform power failure data retention for the meter.

[0029] The present invention has at least the following beneficial effects:

[0030] This invention discloses a power-off data retention circuit and method for a smart meter. It detects both high-voltage and low-voltage power outages using a high-voltage power outage detection circuit and a low-voltage power outage detection circuit. When a high-voltage power outage occurs, data retention is performed first. If the time interval between the high-voltage and low-voltage power outages is greater than or equal to a preset duration, the energy required for data retention is calculated based on the current operating state. Based on this energy requirement, the controller and the power retention circuit are powered sequentially using a capacitor in the low-voltage power outage detection circuit, a supercapacitor in the power supply circuit, and a battery, respectively, to retain the meter data during power outages. When the time interval between a high-voltage power outage and a low-voltage power outage is less than a preset duration, the meter data will not be saved after the high-voltage power outage data is saved. This allows for the differentiation between normal power outages and power outages following voltage dips. Data saving will only be performed again in the case of power outages following voltage dips. The supercapacitor is used for power saving during power outages, reducing the number of times the power supply battery is used and reducing battery wear. Furthermore, a dual power outage detection method is used for power outage data saving, enabling different data saving for normal power outages and power outages following voltage dips, thereby improving the reliability of power outage data saving. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a circuit diagram of the power-off data retention circuit of the smart meter according to an embodiment of the present invention;

[0033] Figure 2 This is a circuit diagram of the high-voltage power failure detection circuit according to an embodiment of the present invention;

[0034] Figure 3 This is a circuit diagram of the low-voltage power failure detection circuit according to an embodiment of the present invention;

[0035] Figure 4 This is a circuit diagram of the power-off power supply circuit according to an embodiment of the present invention;

[0036] Figure 5 This is a flowchart of a smart meter power-off data retention method according to an embodiment of the present invention;

[0037] Figure 6 This is a flowchart of another method for saving data after power failure in a smart meter according to an embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] In the description of this invention, it should be noted that the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0041] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0042] like Figure 1 As shown, the present invention provides a power-off data retention circuit for smart meters, comprising:

[0043] A high-voltage power failure detection circuit is used to detect the three-phase power input and output a high-voltage indication signal to the controller based on the three-phase power input. The controller determines whether a high-voltage power failure has occurred based on the high-voltage indication signal.

[0044] A low-voltage power failure detection circuit is used to detect the low-voltage signal of the low-voltage power supply and send the low-voltage signal to the controller. The controller determines whether a low-voltage power failure has occurred based on the low-voltage signal.

[0045] The power-off power supply circuit, including a supercapacitor and a power supply battery, is used to power the controller and the power-off preservation circuit.

[0046] The controller is used to save power failure data after detecting a power failure. When the time interval between the occurrence of a power failure and a weak power failure is greater than or equal to a preset duration, it calculates the energy required for saving the power failure data based on the current operating state. Based on the energy required for saving the power failure data, it sequentially uses the capacitor in the weak power failure detection circuit, the supercapacitor in the power failure power supply circuit, and the power supply battery to supply power to the controller and the power failure saving circuit to save the meter data. When the time interval between the occurrence of a power failure and a weak power failure is less than the preset duration, it does not save the meter data after saving the power failure data.

[0047] Specifically, the three-phase power input is the original input power of the smart meter. The power failure preservation circuit of the smart meter also includes a first conversion circuit and a second conversion circuit. The first conversion circuit converts the three-phase power input into a low-voltage power supply, and the second conversion circuit converts the low-voltage power supply into a preset power supply.

[0048] The first conversion circuit is an AC-to-DC (AC-DC) circuit, and the second conversion circuit is a DC-to-DC (DC-DC) circuit, both of which are step-down circuits. The first conversion circuit uses an AC-to-DC circuit that includes a high-voltage filter capacitor. The voltage of the low-voltage power supply and the preset power supply can be set according to the actual situation. In one example, the voltage of the low-voltage power supply is 15V, and the voltage of the preset power supply is 5V. Through the first and second conversion circuits, the three-phase power supply can be converted to the preset power supply with a lower voltage value to facilitate powering the various devices in the smart meter.

[0049] The high-voltage power failure detection circuit detects the three-phase power input and outputs a high-voltage status indication signal to the controller. Its main function is to allow the controller to detect high-voltage power failure in advance. After detecting the high-voltage power failure, it makes full use of the energy of the high-voltage filter capacitor in the first conversion circuit to save the power failure data.

[0050] The low-voltage power failure detection circuit detects the low-voltage signal and outputs a low-voltage status indication signal to the controller, which is the final basis for the controller to determine the power failure. The low-voltage power failure detection circuit also has a capacitor, but its energy is much smaller than that of the high-voltage filter capacitor, and it is also used for power failure data storage.

[0051] The power-off power supply circuit includes a supercapacitor and a power supply battery, both of which can power the controller and the power-off preservation circuit.

[0052] The controller can be a microcontroller unit (MCU) or a field-programmable gate array (FPGA). Preferably, the controller is a microcontroller unit.

[0053] The controller determines whether a high-voltage power failure has occurred based on the high-voltage indication signal and whether a low-voltage power failure has occurred based on the low-voltage signal. If the time interval between the occurrence of a high-voltage power failure and a low-voltage power failure is greater than or equal to a preset duration, the current power failure is determined to be a power failure following a voltage dip. In this case, a power failure save operation is required to prevent data loss. It should be understood that the preset duration can be set according to actual conditions, such as a preset duration of 3s, 4s, or 5s.

[0054] The controller calculates the energy required to save power-down data based on the current operating state. The current operating state is the program running position within the controller. Different program running positions correspond to different energy requirements for saving power-down data. By pre-setting the correspondence between program running positions and energy requirements for saving power-down data, the energy required for saving power-down data can be calculated based on the program running position in the future.

[0055] If the energy required for power-down data retention is less than or equal to the energy of the supercapacitor, the supercapacitor powers the controller and power-down retention circuit to retain the meter data. If the energy required for power-down data retention is greater than the energy of the supercapacitor, the battery powers the controller and power-down retention circuit to retain the meter data. After power-down data retention, the battery powers the controller, and the controller enters low-power mode.

[0056] When the time interval between a high-voltage power failure and a low-voltage power failure is less than the preset duration, it is considered a normal power failure and will not cause data loss or errors. The meter data will not be saved during the power failure, the power supply battery will supply power to the controller, and the controller will directly enter a low-power mode, thereby reducing the power supply battery consumption.

[0057] An embodiment of the present invention provides a smart meter power-off data retention circuit. This circuit detects both high-voltage and low-voltage power outages using high-voltage and low-voltage power-off detection circuits. When a high-voltage power outage occurs, data retention is performed first. If the time interval between the high-voltage and low-voltage power outages is greater than or equal to a preset duration, the energy required for data retention is calculated based on the current operating state. Based on this energy requirement, the supercapacitor and battery in the power-off power supply circuit are controlled to sequentially supply power to the controller and the power-off data retention circuit to retain the meter data. When the time interval between a power outage and a low-voltage power outage is less than a preset duration, the meter data will not be saved after the high-voltage power outage data is saved. This allows for the differentiation between normal power outages and power outages following voltage dips. Data saving will only be performed again in the case of power outages following voltage dips. The supercapacitor is used to power up the data saving process first, reducing the number of times the power supply battery is used and minimizing battery wear. Furthermore, a dual power outage detection method is used for data saving, enabling different data saving for normal power outages and power outages following voltage dips, thereby improving the reliability of data saving.

[0058] In some embodiments, such as Figure 2 As shown, the high-voltage power failure detection circuit includes a metering chip U41. The input terminal of the metering chip U41 is connected to the three-phase power input, and the output terminal of the metering chip U41 is connected to the first signal detection terminal of the controller. When all three phase voltages of the three-phase power input are less than the first detection threshold, the high-voltage indication signal output by the output terminal of the metering chip U41 is at a low level. When any phase voltage of the three-phase power input is greater than or equal to the first detection threshold, the high-voltage indication signal output by the output terminal of the metering chip U41 is at a high level. When the high-voltage indication signal detected by the first signal detection terminal of the controller has a falling edge, it is determined that a high-voltage power failure has occurred.

[0059] Specifically, the input terminals of the metering chip U41 are connected to the three-phase voltages of the three-phase power supply. Taking phase A voltage as an example, phases B and C are similar. The voltage divider resistors R239, R223, R240, R243, R253, R252, R241, R214 and the sampling resistor R224 are connected in series. The voltage across resistor R224 is input to the metering chip U41. The metering chip U41 detects the three-phase voltages in real time. When all three-phase voltages are below the first detection threshold, the IRQ pin of the metering chip U41 outputs a low level; otherwise, the IRQ pin outputs a high level. The IRQ pin is connected to the first signal detection terminal of the controller. When the high-voltage indication signal detected by the first signal detection terminal of the controller shows a falling edge, it is determined that a high-voltage power failure has occurred.

[0060] It should be understood that the first detection threshold can be set according to the actual situation, such as 20V, 30V, etc.

[0061] In this embodiment, the metering chip U41 can accurately detect the three-phase voltage. When all three-phase voltages are less than the first detection threshold, it is determined that the high-voltage power has failed. This high-precision detection method can accurately determine whether the high-voltage power has failed, avoiding false alarms. The controller determines the high-voltage power failure by detecting the falling edge of the high-voltage indicator signal. This real-time response mechanism can quickly trigger subsequent power failure processing procedures, ensuring the timeliness of data preservation.

[0062] In some embodiments, such as Figure 3 As shown, the low-voltage power failure detection circuit includes a first resistor R199, a second resistor R204, and a first capacitor C164. The first end of the first resistor R199 is connected to the low-voltage power supply and the positive terminal of the first capacitor C164. The second end of the first resistor R199 is connected to the first end of the second resistor R204 and the second signal detection terminal of the controller. The second end of the second resistor R204 is connected to the negative terminal of the first capacitor C164 and grounded. When the low-voltage signal detected by the second signal detection terminal of the controller is less than the second detection threshold, it is determined that a low-voltage power failure has occurred.

[0063] Specifically, the voltage of the low-voltage power supply is 15V. After being divided by the first resistor R199 and the second resistor R204, the low-voltage voltage signal POWER_DET is input to the second signal detection terminal of the controller. When the low-voltage voltage signal POWER_DET is lower than the second detection threshold, for example, when the low-voltage voltage signal POWER_DET is lower than 0.9V, that is, when the low-voltage power supply is lower than 8.45V, the controller determines that there is a real power failure, and the energy on the first capacitor C164 can be used for power failure data preservation. After calculating the energy required for power failure data preservation, the controller, depending on the specific situation, first uses the energy of the first capacitor C164 in the low-voltage power failure detection circuit, then controls the supercapacitor C161 to supply power, and finally controls the power supply battery to supply power, thus completing the power failure data preservation.

[0064] The low-voltage power failure detection circuit of this invention can effectively detect low-voltage signals. When the voltage is less than the second detection threshold, it is determined that a low-voltage power failure has occurred. It has high reliability and can use the energy on the first capacitor C164 to save power failure data, reducing the wear and tear on the power supply battery.

[0065] In some embodiments, such as Figure 4 As shown, the power-off circuit also includes:

[0066] The power-down preservation circuit has its input terminals connected to the output terminal of the second conversion circuit, the supercapacitor C161, and the power supply battery, respectively. Its output terminals are connected to the controller and the power-down preservation circuit, respectively. It is used to supply power to the controller and the power-down preservation circuit by utilizing the output of the second conversion circuit, the supercapacitor, and the power supply battery.

[0067] A charging and discharging control circuit for supercapacitor C161 includes a charging control circuit and a discharging control circuit. The control terminal of the charging control circuit is connected to the first signal output terminal of the controller and is used to control whether a preset power supply charges supercapacitor C161 according to the first enable signal output by the controller. The control terminal of the discharging control circuit is connected to the second signal output terminal of the controller and is used to control whether supercapacitor C161 discharges according to the second enable signal output by the controller and to provide an input voltage for a power-off preservation power supply circuit. The power-off preservation power supply circuit uses the input voltage provided by the supercapacitor to power the controller and the power-off preservation circuit.

[0068] The battery control circuit is connected to the control terminal and the third signal output terminal of the controller. It is used to control whether the power supply battery provides input voltage to the power-down preservation power circuit according to the third enable signal output by the controller. The power-down preservation power circuit uses the input voltage provided by the power supply battery to power the controller and the power-down preservation circuit.

[0069] The power-down preservation circuit includes a second low-dropout regulator (LDO) U30. The input of the second LDO U30 can come from the second conversion circuit, the supercapacitor C161, and the power supply battery. The energy in the first capacitor C164 in the low-voltage power-down detection circuit is also output to the second LDO U30 through the second conversion circuit. The second LDO U30 converts the input voltage into the power supply voltage V_MCU, thereby powering the controller and the power-down preservation circuit.

[0070] Specifically, the charging control circuit includes transistors V8 and V2, and the discharging control circuit includes transistors V3 and V13. When powered on, the preset power supply V_5.0V is converted into a power supply voltage V_MCU through diode D51 and the second low-dropout linear regulator U30 to power the controller and the power-down preservation circuit. The controller outputs the first enable signal CHARG_CTL through the first signal output terminal to control transistor V8 to conduct, which in turn controls transistor V2 to conduct. The preset power supply V_5.0V charges the supercapacitor C161.

[0071] When power is lost, the controller outputs a first enable signal CHARG_CTL through the first signal output terminal to control transistor V2 to turn off, preventing supercapacitor C161 from backflowing into the preset power supply V_5.0V. When needed, it outputs a second enable signal DISCHARG_CTL through the second signal output terminal to control transistor V13 to turn on, thereby controlling transistor V3 to turn on to supply power to the downstream, reducing the energy loss of supercapacitor C161.

[0072] Furthermore, the supercapacitor C161 charging and discharging control circuit also includes a capacitor power monitoring circuit, which is connected to the supercapacitor C161 and the first detection terminal of the controller, respectively. The controller detects the energy of the supercapacitor C161 through the capacitor power monitoring circuit.

[0073] The capacitor power monitoring circuit includes resistors R158 and R203. After the voltage of supercapacitor C161 is divided by resistors R158 and R203, the capacitor power monitoring signal CAP_AD is input to the controller through the first detection terminal. The controller can detect the voltage of supercapacitor C161 in real time and calculate the energy of supercapacitor C161.

[0074] The supercapacitor C161 charging and discharging control circuit can control the charging and discharging of the supercapacitor C161 according to the controller's instructions, manage energy reasonably, prevent the supercapacitor C161 from backflowing, and ensure sufficient energy supply when power is lost.

[0075] Furthermore, the battery control circuit can also control the power supply of the battery according to the controller's instructions. Combined with the supercapacitor C161, it realizes flexible switching between multiple power supply modes and improves the reliability of power supply.

[0076] In some embodiments, the power supply battery includes a power outage meter reading battery G3 and a clock battery G4, and the battery control circuit includes a power outage meter reading battery control circuit and a clock battery control circuit.

[0077] The power outage meter reading battery control circuit includes a third resistor R106, a fourth resistor R121, and a first low-dropout linear regulator U14. The first terminal of the third resistor R106 is connected to the positive terminal of the power outage meter reading battery G3. The second terminal of the third resistor R106 is connected to the first terminal of the fourth resistor R121 and the enable terminal of the first low-dropout linear regulator U14. The enable terminal of the first low-dropout linear regulator U14 is connected to the fourth signal output terminal of the controller. The second terminal of the fourth resistor R121 is connected to the negative terminal of the power outage meter reading battery G3.

[0078] The clock battery control circuit includes a comparator U27 and a MOSFET V1. The input of the comparator U27 is connected to the output of the first low-dropout linear regulator U14. The output of the comparator U27 is connected to the enable terminal of the active switch V1. The two ends of the active switch V1 are connected to the positive terminal of the clock battery G4 and the input of the power-down retention circuit, respectively.

[0079] Specifically, if the power-on time is short and the supercapacitor C161's energy is insufficient to support the data retention during power outages, the controller's fourth signal output terminal outputs a 6V_EN signal to enable the first low-dropout linear regulator U14. The energy from the power outage meter reading battery G3 is then supplied to the second low-dropout linear regulator U30. The second low-dropout linear regulator U30 converts the input voltage into the supply voltage V_MCU. When the voltage of the power outage meter reading battery G3 is lower than a preset threshold, the comparator U27 outputs a low level, the active switch V1 is turned on, and the energy from the clock battery G4 is supplied to the second low-dropout linear regulator U30. The second low-dropout linear regulator U30 then converts the input voltage into the supply voltage V_MCU for power supply.

[0080] In this embodiment of the invention, the power outage meter reading battery control circuit and the clock battery control circuit control their respective batteries, enabling independent management of the battery power supply status, avoiding mutual interference, and improving the reliability of power outage data retention. By setting two batteries and determining their order of operation to supply power in the power outage state, the inability to retain power outage data when a single battery has too low a charge is avoided, further improving the reliability of power outage data retention.

[0081] Furthermore, the battery control circuit also includes a power outage meter reading battery detection circuit, which includes a fifth resistor and a sixth resistor. The first end of the fifth resistor is connected to the positive terminal of the power outage meter reading battery G3, and the second end of the fifth resistor is connected to the first end of the sixth resistor and the second detection terminal of the controller.

[0082] After the voltage of the power outage meter reading battery G3 is divided by the fifth resistor R102 and the sixth resistor R115, the battery detection signal 6V_AD is input to the controller through the second detection terminal. The controller can detect the voltage of the power outage meter reading battery G3 in real time. If the voltage of the power outage meter reading battery G3 is lower than the preset low voltage threshold, the controller reports to the main station system to remind the power company to replace it in time, so as to avoid the power outage meter reading function from failing due to battery failure and improve the reliability and stability of power outage data storage.

[0083] This invention also provides a method for preserving data after power failure in smart meters, applicable to the power failure preservation circuit of a smart meter as described in any of the above embodiments of this invention, such as... Figure 5 As shown, the method includes:

[0084] Step S101: Receive a high-voltage indication signal and a low-voltage signal; determine whether a high-voltage power failure has occurred based on the high-voltage indication signal and whether a low-voltage power failure has occurred based on the low-voltage signal.

[0085] Step S102: After detecting a power outage, save the meter data after the power outage.

[0086] Step S103: When the time interval between the occurrence of a high-voltage power failure and a low-voltage power failure is greater than or equal to a preset duration, calculate the energy required for power failure data storage based on the current operating status, and control the supercapacitor and power supply battery in the power failure power supply circuit to supply power to the controller and the power failure storage circuit in sequence according to the energy required for power failure data storage, so as to perform power failure data storage of the meter.

[0087] Step S104: When the time interval between the occurrence of a high-voltage power failure and a low-voltage power failure is less than a preset duration, the meter data will not be saved after the high-voltage power failure data is saved.

[0088] Furthermore, before controlling the supercapacitor C161 and the power supply battery in the power-down power supply circuit to supply power to the controller and the power-down data preservation circuit according to the energy required for power-down data preservation, the following is also included:

[0089] The energy required for saving power-down data is determined based on whether the energy of the first capacitor C164 in the low-voltage power-down detection circuit meets the power-down saving requirements. If the energy of the first capacitor C164 meets the power-down saving requirements, the controller and power-down saving circuit are powered through the first capacitor C164 to save the meter data during power-down.

[0090] In one embodiment, the controller is a MUC, and the preset duration is 3 seconds, such as... Figure 6 As shown, the MCU will save the power failure data as soon as it detects a high power failure; when the MCU detects a low power failure, it will first turn off the charging of supercapacitor C161 to prevent reverse leakage of supercapacitor C161, and at the same time calculate the interval between the high power failure and the low power failure.

[0091] If the interval is ≤3s, it is considered a normal power outage process, and no more power outage data is saved. Power is supplied to the power outage meter reading battery G3 and the clock battery G4, and the MCU enters low power mode.

[0092] If the interval is greater than 3 seconds, it is considered a power outage after a voltage dip, and the MCU needs to save the power outage data. The MCU first determines the current operating state, i.e., the current program running position in the MCU, and calculates the energy required to complete the power-down data saving. If the energy of the first capacitor C164 in the low-voltage power-down detection circuit is sufficient, the power-down data is saved through the first capacitor C164, and the power-down meter reading battery G3 and clock battery G4 are turned on, and the MCU enters low-power mode. If the energy of the low-voltage circuit capacitor is insufficient, the energy of the supercapacitor C161 needs to be used. The MCU first determines the current voltage of the supercapacitor C161 and calculates the energy of the supercapacitor C161. If the energy of the supercapacitor C161 is sufficient, the supercapacitor C161 is turned on to complete the power-down data saving, and the power-down capacitor C161 is turned off. The power-down meter reading battery G3 and clock battery G4 are turned on, and the MCU enters low-power mode. If the energy of the supercapacitor C161 is insufficient, the energy of the power-down meter reading battery G3 and clock battery G4 needs to be used. The MCU first enables the power-down meter reading battery G3, and when the energy of the power-down meter reading battery G3 is insufficient, it then enables the clock battery G4 to complete the power-down data saving, and the MCU enters low-power mode.

[0093] The embodiments of the present invention employ a dual power failure judgment method for power failure data storage, which enables different power failure data storage methods for normal power failure and power failure after voltage sag, thereby improving the reliability of power failure data storage.

[0094] After calculating the energy required for power-down data saving, depending on the specific situation, the energy of the first capacitor C164 in the low-voltage power-down detection circuit is first used to control the power supply of the supercapacitor C161, and finally the power supply battery is controlled to complete the power-down data saving. This reduces the number of times the power supply battery is used, reduces the wear and tear of the power supply battery, reduces the probability of battery failure or undervoltage, and thus improves the reliability of power-down data saving.

[0095] The power supply batteries include the power outage meter reading battery G3 and the clock battery G4. By setting up two batteries and determining their order of operation, power is supplied in the power outage state, which avoids the inability to save power-outage data when the power of a single battery is too low, and further improves the reliability of power-outage data saving.

[0096] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope of protection.

Claims

1. A power-off data retention circuit for a smart meter, characterized in that, include: A high-voltage power failure detection circuit is used to detect the three-phase power input and output a high-voltage indication signal to the controller based on the three-phase power input. The controller determines whether a high-voltage power failure has occurred based on the high-voltage indication signal. A low-voltage power failure detection circuit is used to detect the low-voltage signal of the low-voltage power supply and send the low-voltage signal to the controller. The controller determines whether a low-voltage power failure has occurred based on the low-voltage signal. The power-off power supply circuit, including a supercapacitor and a power supply battery, is used to power the controller and the power-off preservation circuit. The controller is used to receive a high-voltage indication signal and a low-voltage signal, and to determine whether a high-voltage power failure has occurred based on the high-voltage indication signal and whether a low-voltage power failure has occurred based on the low-voltage signal. After a high-voltage power outage is detected, the meter data is saved during the power outage. When the time interval between the high-voltage and low-voltage power outages is greater than or equal to a preset duration, the energy required for saving the power outage data is calculated based on the current operating status. The energy required for saving the power outage data is then used to determine whether the energy of the first capacitor in the low-voltage power outage detection circuit meets the power outage saving requirements. If the energy of the first capacitor meets the requirements, the controller and the power outage saving circuit are powered first through the first capacitor to save the meter data. If the energy of the first capacitor does not meet the requirements, the supercapacitor and the power supply battery in the power outage power supply circuit are controlled to sequentially power the controller and the power outage saving circuit to save the meter data. When the time interval between the high-voltage and low-voltage power outages is less than the preset duration, the meter data is not saved during the high-voltage power outage data saving process. The power-off preservation circuit of the smart meter includes a second conversion circuit and: The power-down preservation circuit has its input terminal connected to the output terminal of the second conversion circuit, the supercapacitor, and the power supply battery, respectively, and its output terminal connected to the controller and the power-down preservation circuit, respectively, for using the output of the second conversion circuit, the supercapacitor, and the power supply battery to power the controller and the power-down preservation circuit; A supercapacitor charging and discharging control circuit includes a charging control circuit and a discharging control circuit. The control terminal of the charging control circuit is connected to the first signal output terminal of the controller, and is used to control whether a preset power supply charges the supercapacitor according to the first enable signal output by the controller. The control terminal of the discharging control circuit is connected to the second signal output terminal of the controller, and is used to control whether the supercapacitor discharges according to the second enable signal output by the controller and to provide an input voltage to the power-off preservation power supply circuit. The power-off preservation power supply circuit uses the input voltage provided by the supercapacitor to power the controller and the power-off preservation circuit. A battery control circuit, with its control terminal connected to the third signal output terminal of the controller, is used to control whether the power supply battery provides input voltage to the power-down preservation power circuit according to the third enable signal output by the controller. The power-down preservation power circuit uses the input voltage provided by the power supply battery to power the controller and the power-down preservation circuit. The supercapacitor charging and discharging control circuit also includes a capacitor power monitoring circuit, which is connected to the supercapacitor and the first detection terminal of the controller, respectively. The controller detects the energy of the supercapacitor through the capacitor power monitoring circuit. It receives a high-voltage indication signal and a low-voltage signal, and determines whether a high-voltage power failure has occurred based on the high-voltage indication signal and whether a low-voltage power failure has occurred based on the low-voltage signal.

2. The smart meter power-off retention circuit according to claim 1, characterized in that, The high-voltage power failure detection circuit includes a metering chip. The input terminal of the metering chip is connected to the three-phase power input, and the output terminal of the metering chip is connected to the first signal detection terminal of the controller. When all three-phase voltages of the three-phase power input are less than the first detection threshold, the high-voltage indication signal output by the metering chip is at a low level. When any phase voltage of the three-phase power input is greater than or equal to the first detection threshold, the high-voltage indication signal output by the metering chip is at a high level. When the high-voltage indication signal detected by the first signal detection terminal of the controller has a falling edge, it is determined that a high-voltage power failure has occurred.

3. The smart meter power-off data retention circuit according to claim 1, characterized in that, The low-voltage power failure detection circuit includes a first resistor, a second resistor, and a first capacitor. The first end of the first resistor is connected to the low-voltage power supply and the positive terminal of the first capacitor, respectively. The second end of the first resistor is connected to the first end of the second resistor and the second signal detection terminal of the controller, respectively. The second end of the second resistor is connected to the negative terminal of the first capacitor and grounded. When the low-voltage signal detected by the second signal detection terminal of the controller is less than the second detection threshold, it is determined that a low-voltage power failure has occurred.

4. The smart meter power-off retention circuit according to claim 1, characterized in that, The smart meter power failure preservation circuit further includes a first conversion circuit and a second conversion circuit. The first conversion circuit is used to convert the three-phase power input into the low-voltage power supply, and the second conversion circuit is used to convert the low-voltage power supply into a preset power supply.

5. The smart meter power-off retention circuit according to claim 1, characterized in that, The power supply battery includes a power outage meter reading battery and a clock battery, and the battery control circuit includes a power outage meter reading battery control circuit and a clock battery control circuit; The power outage meter reading battery control circuit includes a third resistor, a fourth resistor, and a first low-dropout linear regulator. The first end of the third resistor is connected to the positive terminal of the power outage meter reading battery. The second end of the third resistor is connected to the first end of the fourth resistor and the enable terminal of the first low-dropout linear regulator. The enable terminal of the first low-dropout linear regulator is connected to the fourth signal output terminal of the controller. The second end of the fourth resistor is connected to the negative terminal of the power outage meter reading battery. The clock battery control circuit includes a comparator and an active switching transistor. The input terminal of the comparator is connected to the output terminal of the first low-dropout linear regulator, and the output terminal of the comparator is connected to the enable terminal of the active switching transistor. The two ends of the active switching transistor are respectively connected to the positive terminal of the clock battery and the input terminal of the power-down retention circuit.

6. The smart meter power-off data retention circuit according to claim 5, characterized in that, The battery control circuit also includes a power outage meter reading battery detection circuit, which includes a fifth resistor and a sixth resistor. The first end of the fifth resistor is connected to the positive terminal of the power outage meter reading battery, and the second end of the fifth resistor is connected to the first end of the sixth resistor and the second detection terminal of the controller.

7. A method for preserving data after a power outage in a smart meter, characterized in that, The method, applied to the power-off retention circuit of a smart meter as described in any one of claims 1 to 6, comprises: Receives a high-voltage indication signal and a low-voltage signal, determines whether a high-voltage power failure has occurred based on the high-voltage indication signal, and determines whether a low-voltage power failure has occurred based on the low-voltage signal; The meter data is saved after a power outage is detected. When the time interval between a high-voltage power failure and a low-voltage power failure is greater than or equal to a preset duration, the energy required for power failure data preservation is calculated based on the current operating status. Based on the energy required for power failure data preservation, the supercapacitor and the power supply battery in the power failure power supply circuit are controlled to supply power to the controller and the power failure preservation circuit in sequence, so as to preserve the meter data during power failure. If the time interval between a high-voltage power outage and a low-voltage power outage is less than a preset duration, the meter data will not be saved after the high-voltage power outage data has been saved.

8. The method for preserving data after power failure in a smart meter according to claim 7, characterized in that, Before controlling the supercapacitor and the power supply battery in the power-down power supply circuit to supply power to the controller and the power-down data storage circuit according to the energy required for power-down data storage, the method further includes: Based on the energy required for power-down data storage, it is determined whether the energy of the first capacitor in the low-voltage power-down detection circuit meets the power-down storage requirements. If the energy of the first capacitor meets the power-down storage requirements, the controller and the power-down storage circuit are first powered through the first capacitor to perform power-down data storage of the meter.

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