Power supply circuit and electric energy meter

Abstract

The utility model discloses a power supply circuit and an electric energy meter, and relates to the power supply field, a rectification module converts an AC power supply into a DC power supply to supply power to a load, a charging module charges a super capacitor, and a power failure monitoring module monitors the AC power supply; the power failure monitoring module controls the controllable switch to be switched off when the alternating-current power supply is powered off, the power failure monitoring module controls the controllable switch to be switched on when the alternating-current power supply is powered off, the super-capacitor and the battery compete to supply power to the load at the moment, the super-capacitor preferentially supplies power to the load due to the fact that the voltage of the super-capacitor is larger than the rated output voltage of the battery when the super-capacitor is fully charged, and then the battery supplies power to the load. When the alternating current power supply is powered down, the super capacitor and the battery supply power to the load in sequence, the power consumption of the super capacitor is small, and the charge-discharge cycle life is longer than that of the battery, so that the use of the battery is reduced, the power consumption of the battery is reduced, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The utility model relates to the field of power supply, in particular to a power supply circuit and an electric energy meter. Background Art

[0002] The electric energy meter is mainly used for electric energy metering. When the electric energy meter works, it generally uses alternating current for power supply. Specifically, after the alternating current is converted into direct current, it supplies power to the electric energy meter; when the alternating current loses power, a battery is used to supply power to it.

[0003] At present, the electric energy meter uses two power supplies for power supply, including alternating current and battery. Due to the requirements of the national grid standard, the electric energy meter needs to perform power outage active reporting and full voltage loss detection within one minute after the alternating current loses power. After the alternating current loses power, only the battery can be used to supply power to the electric energy meter. Since the power consumption of the battery is relatively large during the use of the electric energy meter, the service life of the battery is seriously affected. Summary of the Utility Model

[0004] The purpose of the utility model is to provide a power supply circuit and an electric energy meter, which reduce the use of the battery, reduce the power consumption of the battery and improve the service life of the battery.

[0005] To solve the above technical problems, the utility model provides a power supply circuit, including:

[0006] A rectification module, whose input end is connected to an AC power supply, and is used to convert the AC power supply into direct current;

[0007] A super capacitor, the positive electrode of the super capacitor is connected to the power supply end of the load, and the negative electrode is grounded;

[0008] A charging module, the input end of the charging module is connected to the output end of the rectification module, and the output end is connected to the positive electrode of the super capacitor, and is used to charge the super capacitor based on the voltage at the output end of the rectification module when the AC power supply is normally powered on;

[0009] A power failure monitoring module, the input end of the power failure monitoring module is connected to the output end of the rectification module, and is used to control the controllable switch to be disconnected when the AC power supply is normally powered on, and control the controllable switch to be closed when the AC power supply loses power;

[0010] A controllable switch, the control end of the controllable switch is connected to the output end of the power failure monitoring module, the first end of the controllable switch is connected to the battery, and the second end is connected to the power supply end of the load. The voltage when the super capacitor is fully charged is greater than the rated output voltage of the battery.

[0011] Optionally, the charging module includes:

[0012] A converter, the input end of the converter is connected to the output end of the rectification module, and the output end is connected to the anode of the first diode, and is used to step down the direct current;

[0013] The first diode, the cathode of the first diode is connected to the first end of the first resistor;

[0014] The first resistor, the second end is connected to the positive electrode of the super capacitor.

[0015] Optionally, the charging module further includes:

[0016] The second diode, the anode of the second diode is connected to the positive electrode of the super capacitor, and the cathode is connected to the power supply terminal of the load;

[0017] The third diode, the anode of the third diode is connected to the output terminal of the rectification module, and the cathode is connected to the power supply terminal of the load.

[0018] Optionally, it further includes:

[0019] The voltage stabilizing module, the input terminal of the voltage stabilizing module is connected to the positive electrode of the super capacitor, and the output terminal is connected to the power supply terminal of the load, and is used to step down the input voltage of the voltage stabilizing module to a fixed voltage value.

[0020] Optionally, the battery includes:

[0021] The first battery, the first battery is detachably arranged in the electric energy meter;

[0022] The second battery, the second battery is fixedly arranged in the electric energy meter;

[0023] The controllable switch includes:

[0024] The first controllable switch, the first end of the first controllable switch is connected to the positive electrode of the first battery, and the second end is connected to the power supply terminal of the load, and is used to disconnect when receiving a disconnection control signal and conduct when receiving a conduction control signal;

[0025] The second controllable switch, the first end of the second controllable switch is connected to the positive electrode of the second battery, and the second end is connected to the power supply terminal of the load;

[0026] The power failure monitoring module includes:

[0027] The voltage acquisition module, the input terminal of the voltage acquisition module is connected to the output terminal of the rectification module, and the output terminal is connected to the input terminal of the first conversion module, and is used to acquire the rectified voltage;

[0028] The first conversion module, the output terminal of the first conversion module is respectively connected to the first input terminal of the second conversion module and the control terminal of the first controllable switch, and is used to output a disconnection control signal when the AC power supply is normally powered on and output a conduction control signal when the AC power supply loses power;

[0029] The second conversion module, the second input terminal of the second conversion module is connected to the positive electrode of the first battery, and the output terminal is connected to the control terminal of the second controllable switch, and is used to control the second controllable switch to disconnect when receiving a disconnection control signal, and to control the second controllable switch to disconnect when receiving a conduction control signal and the voltage of the first battery is not less than the undervoltage value, and to control the second controllable switch to conduct when receiving a conduction control signal and the voltage of the first battery is less than the undervoltage value.

[0030] Optionally, the first conversion module includes:

[0031] The first switching tube, the control terminal of the first switching tube is connected to the output terminal of the voltage acquisition module, the first terminal is connected to the first terminal of the second resistor, and the second terminal is grounded, and is used to conduct when the AC power supply is normally powered on and to disconnect when the AC power supply loses power;

[0032] The second resistor, the second terminal of the second resistor is connected to the direct current;

[0033] The second switching tube, the control terminal of the second switching tube is connected to the first terminal of the first switching tube, the first terminal is connected to the first terminal of the third resistor, and the second terminal is grounded, and is used to disconnect when the first switching tube conducts and to conduct when the first switching tube disconnects;

[0034] The third resistor, the second terminal of the third resistor is connected to the direct current;

[0035] The fourth resistor, the first terminal of the fourth resistor is connected to the first terminal of the third resistor, and the second terminal is grounded.

[0036] Optionally, the second conversion module includes:

[0037] The fourth diode, the anode of the fourth diode is connected to the output terminal of the first conversion module, and the cathode is connected to the input terminal of the power-off detection chip;

[0038] The fifth diode, the anode of the fifth diode is connected to the positive electrode of the first battery, and the cathode is connected to the input terminal of the power-off detection chip;

[0039] The power-off detection chip, the output terminal of the power-off detection chip is connected to the control terminal of the second controllable switch, and is used to control the second controllable switch to disconnect when receiving a disconnection control signal, and to control the second controllable switch to disconnect when receiving a conduction control signal and the voltage of the first battery is not less than the undervoltage value, and to control the second controllable switch to conduct when receiving a conduction control signal and the voltage of the first battery is less than the undervoltage value.

[0040] Optionally, the first conversion module further includes:

[0041] The first capacitor, the first terminal of the first capacitor is connected to the output terminal of the voltage acquisition module, and the second terminal is grounded;

[0042] The fifth resistor, the first end of the fifth resistor is connected to the output end of the voltage acquisition module, and the second end is connected to the control end of the first switching transistor;

[0043] The second capacitor, the first end of the second capacitor is connected to the first end of the second switching transistor, and the second end is grounded;

[0044] The sixth resistor, the first end of the sixth resistor is connected to the first end of the second switching transistor, and the second end is connected to the first input end of the second conversion module.

[0045] Optionally, the second conversion module further includes:

[0046] The sixth diode, the anode of the sixth diode is connected to the positive electrode of the first battery, and the cathode is connected to the first end of the first controllable switch;

[0047] The seventh diode, the anode of the seventh diode is connected to the positive electrode of the second battery, and the cathode is connected to the first end of the second controllable switch.

[0048] To solve the above problems, the present utility model further provides an electric energy meter, including the above-mentioned power supply circuit, and further including a battery, and the battery is connected to the power supply circuit.

[0049] The present utility model provides a power supply circuit and an electric energy meter, including a rectification module, a super capacitor, a charging module, a power failure monitoring module, and a controllable switch. The rectification module converts an AC power supply into a DC power supply to supply power to a load, and at the same time uses the charging module to charge the super capacitor. The power failure monitoring module monitors the AC power supply. When the AC power supply is normally powered on, the power failure monitoring module controls the controllable switch to be disconnected. When the AC power supply loses power, the power failure monitoring module controls the controllable switch to be turned on. At this time, the super capacitor and the battery compete to supply power to the load. Also, since the voltage when the super capacitor is fully charged is greater than the rated output voltage of the battery, the super capacitor preferentially supplies power to the load. When the voltage of the super capacitor is less than the rated output voltage of the battery, the battery supplies power to the load. Therefore, in the present application, when the AC power supply loses power, the order of supplying power to the load is the super capacitor and then the battery. Also, because the power consumption of the super capacitor is small and the charge-discharge cycle life is higher than that of the battery, the use of the battery is reduced, the power consumption of the battery is reduced, and the service life of the battery is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for the prior art and the embodiments. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0051] Figure 1 The structural schematic diagram of a power supply circuit provided by the present utility model;

[0052] Figure 2 This is a specific structure diagram of a power supply circuit provided by the present utility model. Specific embodiments

[0053] The core of the present utility model is to provide a power supply circuit and an electric energy meter, which reduce the use of batteries, lower the battery power consumption and improve the service life of the batteries.

[0054] To make the objectives, technical solutions and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Apparently, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0055] Please refer to Figure 1 , Figure 1 This is a schematic structural diagram of a power supply circuit provided by the present utility model.

[0056] The power supply circuit includes:

[0057] A rectification module 1, whose input terminal is connected to an AC power supply and is used to convert the AC power supply into direct current;

[0058] A super capacitor C, the positive electrode of the super capacitor C is connected to the power supply terminal of the load, and the negative electrode is grounded;

[0059] A charging module 2, the input terminal of the charging module 2 is connected to the output terminal of the rectification module 1, and the output terminal is connected to the positive electrode of the super capacitor C, and is used to charge the super capacitor C based on the voltage at the output terminal of the rectification module 1 when the AC power supply is normally powered on;

[0060] A power-off monitoring module 3, the input terminal of the power-off monitoring module 3 is connected to the output terminal of the rectification module 1, and is used to control the controllable switch 4 to be disconnected when the AC power supply is normally powered on and control the controllable switch 4 to be closed when the AC power supply is powered off;

[0061] A controllable switch 4, the control terminal of the controllable switch 4 is connected to the output terminal of the power-off monitoring module 3, the first terminal of the controllable switch 4 is connected to the battery B, the second terminal is connected to the power supply terminal of the load, and the voltage when the super capacitor C is fully charged is greater than the rated output voltage of the battery B.

[0062] In this application, in order to minimize the use of battery B as much as possible, in addition to the AC power supply and battery B, a supercapacitor C is additionally provided for the power supply of the load. The power supply priorities of the load are set from high to low as follows: AC power supply, supercapacitor C, and battery B. It should be noted that the load here can be the MCU (Microcontroller Unit) in the electric energy meter.

[0063] Specifically, to achieve the above functions, when the AC power supply is normally powered on, the AC power supply preferentially powers the load. Specifically, the rectification module 1 converts the AC power supply into direct current to power the load, and at the same time charges the supercapacitor C through the charging module 2. In addition, the power-off monitoring module 3 monitors whether the AC power supply is powered off. If the AC power supply is normally powered on, the power-off monitoring module 3 controls the controllable switch 4 to disconnect. If the AC power supply is powered off, the controllable switch 4 closes. When the controllable switch 4 is closed, the supercapacitor C and the battery B compete to power the load. Since the voltage when the supercapacitor C is fully charged is greater than the rated output voltage of the battery B, the supercapacitor C preferentially powers the load. When the voltage of the supercapacitor C drops and is lower than the rated output voltage of the battery B, the battery B powers the load.

[0064] Taking the specification of the supercapacitor C as 1.5F / 5.5V as an example, the 220V AC power supply can be first converted into 12V direct current by the rectification module 1, and then the 12V direct current is converted into 5.7V to power the load and charge the 1.5F / 5.5V supercapacitor C at the same time. When the AC power supply is powered on, the power-off monitoring module 3 outputs a disconnection control signal to control the controllable switch 4 to disconnect; when the AC power supply is powered off, the power-off monitoring module 3 outputs a closing control signal to control the controllable switch 4 to close. The supercapacitor C that is fully charged preferentially powers the load. When the voltage of the supercapacitor C is less than the rated voltage of the battery B, at this time, the battery B powers the load.

[0065] It is not difficult to understand that in practical applications, the controllable switch 4 can be two identical MOS (Metal-Oxide-Semiconductor Field-Effect Transistor) transistors, or a single-pole triple-throw switch. This application does not make special limitations here.

[0066] It can be seen that when the AC power supply is powered off, the order of powering the load is the supercapacitor C and the battery B in sequence. Also, because the power consumption of the supercapacitor C is small and its charge-discharge cycle life is higher than that of the battery B, the use of the battery B is reduced, the power consumption of the battery B is lowered, and the service life of the battery B is extended.

[0067] Based on the above embodiments:

[0068] Please refer toFigure 2 , Figure 2 is a specific structural diagram of a power supply circuit provided by the present utility model.

[0069] As an alternative embodiment, the charging module 2 includes:

[0070] A converter, the input end of the converter is connected to the output end of the rectification module 1, and the output end is connected to the anode of the first diode D1, for step - down processing of direct current;

[0071] The first diode D1, the cathode of the first diode D1 is connected to the first end of the first resistor R1;

[0072] The first resistor R1, the second end is connected to the positive electrode of the super capacitor C.

[0073] Considering that the voltage of the direct current output by the rectification module 1 is usually larger than the charging voltage of the super capacitor C, therefore, in this application, the charging module 2 includes a converter. Specifically, the converter can be a DC / DC converter for step - down processing of direct current. For example, it can step down 12V to 5.7V. The step - down processed direct current powers the load and also charges the super capacitor C at the same time. In order to avoid the current of the super capacitor C flowing back into the direct current when the AC power supply loses power, the charging module 2 also includes the first diode D1 connected in to achieve the function of preventing backflow. At the same time, the first resistor R1 is set to play a role in current limiting to avoid excessive charging current damaging the super capacitor C when the super capacitor C is charged.

[0074] It should be noted that in actual application, if the direct current output by the rectification module 1 can directly charge the super capacitor C, the converter may not be required for step - down operation.

[0075] It can be seen that by setting the first diode D1 and the first resistor R1 in the charging module 2, when the AC power supply loses power, it can prevent the current of the super capacitor C from flowing back into the AC power supply and can protect the super capacitor C.

[0076] As an alternative embodiment, the charging module 2 further includes:

[0077] The second diode D2, the anode of the second diode D2 is connected to the positive electrode of the super capacitor C, and the cathode is connected to the power supply end of the load;

[0078] The third diode D3, the anode of the third diode D3 is connected to the output end of the rectification module 1, and the cathode is connected to the power supply end of the load.

[0079] It can be understood that considering that when the AC power supply powers the load, the second diode D2 can prevent the current output by the rectification module 1 from flowing back into the super capacitor C. When the super capacitor C powers the load, setting the third diode D3 can prevent the current from flowing back from the super capacitor C into the AC power supply.

[0080] It can be seen that when the AC power supply powers the load or the super capacitor C powers the load, the second diode D2 and the third diode D3 are set to achieve the function of preventing reverse current, improving the reliability of the circuit.

[0081] As an optional embodiment, it further includes:

[0082] A voltage regulation module, the input end of the voltage regulation module is connected to the positive electrode of the super capacitor C, and the output end is connected to the power supply end of the load, for stepping down the input voltage of the voltage regulation module to a fixed voltage value.

[0083] Considering that the capacity of the super capacitor C is limited and the stored electric energy is limited, in order to achieve power-off active reporting and full voltage loss detection during the power supply stage of the super capacitor C when the AC power supply loses power, the rated charging voltage of the super capacitor C is usually set higher than the power supply voltage of the load. Therefore, in this application, a voltage regulation module is set to step down the voltage output by the super capacitor through the voltage regulation module and output a stable voltage to the load, reducing the probability of load damage.

[0084] Specifically, when the AC power supply powers the load, the voltage regulation module steps down the voltage of the AC power supply to a fixed voltage value and then stably outputs it to the load. When the super capacitor C powers the load, the voltage regulation module steps down the output voltage of the super capacitor C to a fixed voltage value, converting the fluctuating input voltage into a stable voltage to power the load, so as to ensure the stability of the power supply.

[0085] Specifically, the voltage regulation module may include an LDO (Low Dropout Regulator) U1. In addition, a third capacitor C3 and a fourth capacitor C4 may be set in the voltage regulation module to filter the input voltage and output voltage of the voltage regulation module. Among them, the first end of the third capacitor C3 is connected to the input end of the voltage regulator U1, and the second end is grounded. The first end of the fourth capacitor C4 is connected to the output end of the voltage regulation module, and the second end is grounded.

[0086] In order to prevent the current output by the battery from flowing back to the super capacitor or the AC power supply, a diode D8 is set at the power supply end of the load for preventing reverse current, playing a certain protective role for the voltage regulator U1.

[0087] It is not difficult to understand that when the AC power supply powers the load or the super capacitor C powers the load, the voltage regulator U1 stabilizes the direct current and the voltage of the super capacitor to a fixed value and filters it to provide to the load. For example, the fixed value of the voltage regulator U1 here is 4V. The voltage regulator U1 steps down and stabilizes the 5.7V direct current to 4V. Similarly, it steps down and stabilizes the 5.5V super capacitor to 4V, thereby achieving stable and reliable power supply to the load.

[0088] It can be seen that by setting the voltage regulator U1 in the power supply circuit of the present application, the voltage provided by the AC power supply and the super capacitor C is stepped down, and the stepped-down voltage is provided to the load, which can ensure that the load receives a stable voltage without noise, and improves the reliability of the power supply circuit to a certain extent.

[0089] As an alternative embodiment, the battery B includes:

[0090] The first battery B1 is detachably arranged in the electric energy meter;

[0091] The second battery B2 is fixedly arranged in the electric energy meter;

[0092] The controllable switch 4 includes:

[0093] The first controllable switch 41, the first end of the first controllable switch 41 is connected to the positive electrode of the first battery B1, and the second end is connected to the power supply end of the load, and is used to disconnect when receiving a disconnection control signal and conduct when receiving a conduction control signal;

[0094] The second controllable switch 42, the first end of the second controllable switch 42 is connected to the positive electrode of the second battery B2, and the second end is connected to the power supply end of the load;

[0095] The power-off monitoring module 3 includes:

[0096] The voltage acquisition module, the input end of the voltage acquisition module is connected to the output end of the rectification module 1, and the output end is connected to the input end of the first conversion module, and is used to acquire the rectified voltage;

[0097] The first conversion module, the output end of the first conversion module is respectively connected to the first input end of the second conversion module and the control end of the first controllable switch 41, and is used to output a disconnection control signal when the AC power supply is normally powered on and output a conduction control signal when the AC power supply is powered off;

[0098] The second conversion module, the second input end of the second conversion module is connected to the positive electrode of the first battery B1, and the output end is connected to the control end of the second controllable switch 42, and is used to control the second controllable switch 42 to disconnect when receiving a disconnection control signal, control the second controllable switch 42 to disconnect when receiving a conduction control signal and the voltage of the first battery B1 is not less than the undervoltage value, and control the second controllable switch 42 to conduct when receiving a conduction control signal and the voltage of the first battery B1 is less than the undervoltage value.

[0099] It should be noted that in this application, the first battery B1 is a stop-display battery, the second battery B2 is a clock battery, and the power supply priority of the stop-display battery is higher than that of the clock battery. The stop-display battery is a replaceable battery B, and the clock battery is a non-replaceable battery B. Taking the load as the MCU as an example, when the supercapacitor C supplies power to the load, under normal circumstances, it can meet the requirements of power-off reporting and full-voltage-loss detection within one minute of power-off. When the voltage of the supercapacitor C is less than the rated voltage of the battery, the first battery B1 supplies power to the MCU. When the first battery B1 is undercharged, the MCU usually enters the low-power mode at this time, and then the second battery B2 supplies power to the MCU.

[0100] Specifically, when the AC power supply is normally powered on, the voltage acquisition module acquires the direct current rectified by the rectification module 1. When the first conversion module determines that the AC power supply is normally powered on based on the rectified voltage, it outputs a disconnection control signal, and the first controllable switch 41 disconnects. When the second conversion module receives the disconnection control signal output by the first conversion module, it controls the second controllable switch 42 to disconnect. At this time, neither the first battery B1 nor the second battery B2 supplies power to the load. When the AC power supply loses power, the first conversion module outputs a conduction control signal based on the rectified voltage when it determines that the AC power supply has lost power. At this time, the first controllable switch 41 conducts. When the second conversion module receives the conduction control signal output by the first conversion module and the voltage of the first battery B1 is not less than the undervoltage value, it controls the second controllable switch 42 to disconnect. At this time, the first battery B1 supplies power to the load. If the voltage of the first battery B1 is less than the undervoltage value, it controls the second controllable switch 42 to conduct. At this time, the second battery B2 supplies power to the load.

[0101] It can be understood that the controllable switch 4 is a PMOS transistor. Among them, the first controllable switch 41 is the first PMOS transistor, and the second controllable switch 42 is the second PMOS transistor. The gate of the first PMOS transistor is connected to the output terminal of the first conversion module, the source is connected to the first battery B1, and the drain is connected to the power supply terminal of the load. The gate of the second PMOS transistor is connected to the output terminal of the second conversion module, the source is connected to the second battery B2, and the drain is connected to the power supply terminal of the load. In addition, an eleventh resistor R11 is provided at the gate of the first PMOS transistor, which has a current-limiting effect and can protect the first PMOS transistor to prevent it from being damaged due to excessive current. When the AC power supply is normally powered on, the first PMOS transistor disconnects, and the second PMOS transistor disconnects. At this time, the battery B does not supply power to the load. When the AC power supply loses power, the first conversion module outputs a conduction control signal. When the first PMOS transistor receives the conduction control signal, it conducts. When the second conversion module receives the conduction control signal output by the first conversion module and the voltage of the first battery B1 is not less than the undervoltage value, it controls the second PMOS transistor to conduct, and the second battery B2 supplies power to the load.

[0102] It should be noted that the controllable switch 4 can also be a single-pole triple-throw switch. The first fixed terminal of the single-pole triple-throw switch is connected to the positive electrode of the first battery B1, the second fixed terminal is connected to the positive electrode of the second battery B2, the third fixed terminal is suspended, and the moving terminal is connected to the power supply terminal of the load. When the AC power supply is normally powered on, the moving terminal of the single-pole triple-throw switch is connected to the third fixed terminal. When the AC power supply loses power, the first conversion module outputs a conduction control signal, and the moving terminal of the single-pole triple-throw switch is connected to the first fixed terminal, and the load is powered by the first battery B1. If the AC power supply is in a power-off state for a long time, the voltage of the first battery B1 is consumed to below the undervoltage value. At this time, the moving terminal of the single-pole triple-throw switch is connected to the second fixed terminal, and the load is continuously powered by the second battery B2.

[0103] It is not difficult to understand that the voltage acquisition module includes a voltage division circuit formed by the seventh resistor R7 and the eighth resistor R8 connected in series to the ground. When the AC power supply is normally powered on, the voltage acquisition module divides the voltage of the AC power supply and provides direct current to the first conversion module.

[0104] It can be seen that when the AC power supply loses power and the voltage of the super capacitor C is less than the rated output voltage of the battery B, the first battery B1 supplies power preferentially. When the voltage of the first battery B1 is less than the undervoltage value, the second battery B2 supplies power. Therefore, the power supply sequence of the load is the AC power supply, the super capacitor C, the first battery B1, and the second battery B2 in turn. Thus, the use of the battery B is reduced, the consumption of the battery B is reduced, and the service life of the battery B is extended.

[0105] In addition, compared with the prior art in which only the non-replaceable second battery B2 is usually provided, in the solution of the present application, a replaceable first battery B1 is additionally provided, and the power supply priority of the first battery B1 is higher than that of the second battery B2, thereby further reducing the use of the second battery B2 and improving the service life of the electric energy meter.

[0106] As an optional embodiment, the first conversion module includes:

[0107] A first switching tube Q1, the control terminal of the first switching tube Q1 is connected to the output terminal of the voltage acquisition module, the first terminal is connected to the first terminal of the second resistor R2, and the second terminal is grounded, and is used to conduct when the AC power supply is normally powered on and disconnect when the AC power supply loses power;

[0108] A second resistor R2, the second terminal of the second resistor R2 is connected to direct current;

[0109] A second switching tube Q2, the control terminal of the second switching tube Q2 is connected to the first terminal of the first switching tube Q1, the first terminal is connected to the first terminal of the third resistor R3, and the second terminal is grounded, and is used to disconnect when the first switching tube Q1 conducts and conduct when the first switching tube Q1 disconnects;

[0110] A third resistor R3, the second terminal of the third resistor R3 is connected to direct current;

[0111] The fourth resistor R4, the first end of the fourth resistor R4 is connected to the first end of the third resistor R3, and the second end is grounded.

[0112] Specifically, when the AC power supply is normally powered on, the first switching transistor Q1 conducts based on the voltage collected by the voltage acquisition module, and the second switching transistor Q2 is turned off. At this time, the voltage value output at the output end of the first conversion module is the divided voltage value of the third resistor R3 and the fourth resistor R4, which is the conduction control signal. When the AC power supply loses power, the first switching transistor Q1 is turned off, and the second switching transistor Q2 is turned off. At this time, the voltage value output at the output end is 0, which is the disconnection control signal.

[0113] In practical applications, the first switching transistor Q1 is the first NPN transistor, and the second switching transistor Q1 is the second NPN transistor. Specifically, when the AC power supply is powered on, the base of the first NPN transistor is connected to the voltage acquisition module and conducts based on the collected voltage, that is, there is a voltage difference between the base and the emitter of the first NPN transistor. The second NPN transistor is turned off based on the conduction state of the first NPN transistor. At this time, the conduction control signal is output to control the conduction of the controllable switch 4. When the AC power supply loses power, the first NPN transistor and the second NPN transistor are turned off because they are not powered. At this time, the conduction control signal is output to control the conduction of the controllable switch 4.

[0114] It can be seen that when the AC power supply is powered on, the first switching transistor Q1 conducts, the second switching transistor Q2 is turned off, and the output disconnection control signal controls the disconnection of the controllable switch 4; when the AC power supply loses power, the first switching transistor Q1 and the second switching transistor Q2 are both turned off, and the output conduction control signal controls the conduction of the controllable switch 4. The first conversion module provided in this embodiment can reliably detect whether the AC power supply loses power, and the circuit structure is simple.

[0115] As an alternative embodiment, the second conversion module includes:

[0116] The fourth diode D4, the anode of the fourth diode D4 is connected to the output end of the first conversion module, and the cathode is connected to the input end of the power failure detection chip;

[0117] The fifth diode D5, the anode of the fifth diode D5 is connected to the positive electrode of the first battery B1, and the cathode is connected to the input end of the power failure detection chip;

[0118] The power failure detection chip U2, the output end of the power failure detection chip U2 is connected to the control end of the second controllable switch 42, and is used to control the disconnection of the second controllable switch 42 when receiving the disconnection control signal, control the disconnection of the second controllable switch 42 when receiving the conduction control signal and the voltage of the first battery B1 is not less than the undervoltage value, and control the conduction of the second controllable switch 42 when receiving the conduction control signal and the voltage of the first battery B1 is less than the undervoltage value.

[0119] Considering that when powering the load, the first battery B1 will consume power when continuously powering the load, it will have undervoltage after consuming a certain amount of power, and the second battery B2 needs to be switched after the undervoltage reaches a certain threshold. This application sets a power-off detection chip U2, and the power-off detection chip U2 has a set detection threshold. When the input voltage of the power-off detection chip U2 is less than the detection threshold, it outputs a high-impedance state, that is, a disconnection control signal, to control the disconnection of the second controllable switch 42.

[0120] Specifically, when the AC power is powered on, when the power-off detection chip U2 receives the disconnection control signal output from the first conversion module, it controls the second controllable switch 42 to disconnect. When the AC power is powered off, when the power-off detection chip U2 receives the conduction control signal and the voltage of the first battery B1 is not less than the undervoltage value, it controls the second controllable switch 42 to disconnect. At this time, the first battery B1 powers the load. When the power-off detection chip U2 receives the conduction control signal and the voltage of the first battery B1 is less than the undervoltage value, it controls the second controllable switch 42 to conduct. At this time, the second battery B2 powers the load.

[0121] The following lists an example to illustrate: The standard voltage of the first battery B1 is 3.6V, the standard voltage of the second battery B2 is 3.6V, and the detection threshold of the power-off detection chip U2 is 3V. When the power of the first battery B1 is not less than 3V, at this time, the power-off monitoring chip U2 controls the second controllable switch 42 to disconnect, and the first battery B1 powers the load. However, when the first battery B1 is lower than 3V, the power-off detection chip U2 will control the second controllable switch 42 to conduct, and the second battery B2 powers the load. The fourth diode D4 and the fifth diode D5 are arranged at the input end of the power-off detection chip to achieve the anti-backflow between the first battery B1 and the first conversion module.

[0122] It should be noted that the first end of the ninth resistor R9 is connected to the output end of the power-off detection chip U2, the second end is connected to the first end of the tenth resistor R10, and the second resistor R2 is connected to the source electrode of the second PMOS transistor. When the first battery B1 is lower than the detection threshold of the power-off detection chip U2, the power-off detection chip U2 outputs a conduction control signal, and the ninth resistor R9 and the tenth resistor R10 divide the voltage and ground, controlling the second controllable switch 42 to conduct.

[0123] It can be seen that setting a power-off detection module in the second conversion module can control the power supply priority of the first battery B1 to be higher than that of the second battery B2 to power the load. In addition, setting the fourth diode D4 and the fifth diode D5 realizes the anti-backflow function.

[0124] As an optional embodiment, the first conversion module further includes:

[0125] The first capacitor C1, the first end of the first capacitor C1 is connected to the output end of the voltage acquisition module, and the second end is grounded;

[0126] The fifth resistor R5, the first end of the fifth resistor R5 is connected to the output end of the voltage acquisition module, and the second end is connected to the control end of the first switching tube Q1;

[0127] The second capacitor C2, the first end of the second capacitor C2 is connected to the first end of the second switching tube Q2, and the second end is grounded;

[0128] The sixth resistor R6, the first end of the sixth resistor R6 is connected to the first end of the second switching tube Q2, and the second end is connected to the first input end of the second conversion module.

[0129] It can be understood that setting the first capacitor C1 in the first conversion module can filter the voltage collected by the voltage acquisition module and obtain a stable voltage. The fifth resistor R5 can limit the current of the control end of the first switching tube Q1 to protect the first switching tube Q1. The second capacitor C2 is used to filter the output voltage, and the sixth resistor R6 limits the current at the output end, which can be used to protect the first controllable switch 41 and the power-down detection chip U2.

[0130] It can be seen that setting the fifth resistor R6 at the output end of the voltage acquisition module can prevent the first switching tube Q1 from being burned out due to excessive current. Setting the first capacitor C1 and the second capacitor C2 and directly grounding them, the noise filtered by the capacitors can be directly introduced to the ground, making the direct current smoother and the filtered voltage more accurate, thus achieving the filtering effect.

[0131] As an optional embodiment, the second conversion module further includes:

[0132] The sixth diode D6, the anode of the sixth diode D6 is connected to the positive electrode of the first battery B1, and the cathode is connected to the first end of the first controllable switch 41;

[0133] The seventh diode D7, the anode of the seventh diode D7 is connected to the positive electrode of the second battery B2, and the cathode is connected to the first end of the second controllable switch 42.

[0134] Specifically, the second conversion module is also provided with the sixth diode D6 and the seventh diode D7. The sixth diode D6 can prevent the current from flowing back to the first battery B1 when the super capacitor C or the second battery supplies power; the seventh diode D7 can prevent the current from flowing back to the second battery B2 when the super capacitor C or the first battery B1 supplies power.

[0135] It can be seen that when supplying power to the load, setting the sixth diode D6 and the seventh diode D7 can reduce the influence of the backflow current on the battery B, and can also improve the reliability and stability of the battery B supplying power to the load.

[0136] The present utility model further provides an electric energy meter, which includes the power supply circuit as described above, and further includes a battery B, and the battery B is connected to the power supply circuit.

[0137] It can be understood that the present utility model can also install the battery B and the power supply circuit as a whole in the electric energy meter. When the AC power supply is normally powered on, the superjunction capacitor C and the battery B supply power to the load. When the AC power supply loses power, when the supercapacitor C supplies power to the load, the voltage meter has met the power outage reporting and full voltage loss detection within 1 minute, and then the battery B supplies power to the load. At this time, the battery B supplies a small amount of power to the clock inside the load. Since the loss of the supercapacitor C is lower than that of the battery B and the charge and discharge times are more than those of the battery B, the use of the battery B is reduced to a certain extent.

[0138] It can be seen that when the AC power supply loses power, the order of supplying power to the load is the supercapacitor C and the battery B in sequence. Also, because the power consumption of the supercapacitor C is small and the charge and discharge cycle life is higher than that of the battery B, the use of the battery B is reduced, the power consumption of the battery B is reduced, and the service life of the battery B is increased.

[0139] It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0140] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present utility model. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present utility model. Therefore, the present utility model will not be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A power supply circuit, characterized in that: include: A rectifier module, the input end of which is connected to an AC power source and is used to convert the AC power source into a DC power source; A supercapacitor, wherein the positive electrode of the supercapacitor is connected to the power supply end of the load, and the negative electrode is grounded; A charging module, wherein the input end of the charging module is connected to the output end of the rectifier module, and the output end is connected to the positive electrode of the supercapacitor, and is used to charge the supercapacitor based on the voltage at the output end of the rectifier module when the AC power supply is normally powered on; A power-off monitoring module, the input end of which is connected to the output end of the rectifier module, and is used to control the controllable switch to be disconnected when the AC power supply is normally powered on, and to control the controllable switch to be closed when the AC power supply is powered off; The controllable switch, the control end of the controllable switch is connected to the output end of the power-off monitoring module, the first end of the controllable switch is connected to the battery, and the second end is connected to the power supply end of the load, and the voltage of the supercapacitor when fully charged is greater than the rated output voltage of the battery.

2. The power supply circuit according to claim 1, characterized in that: The charging module comprises: A converter, wherein the input end of the converter is connected to the output end of the rectifier module, and the output end of the converter is connected to the anode of the first diode, and is used to step down the DC power; The first diode, wherein the cathode of the first diode is connected to the first end of the first resistor; The second end of the first resistor is connected to the positive electrode of the super capacitor.

3. The power supply circuit according to claim 1, characterized in that: The charging module also includes: a second diode, wherein an anode of the second diode is connected to a positive electrode of the supercapacitor, and a cathode of the second diode is connected to a power supply end of the load; A third diode, wherein an anode of the third diode is connected to the output end of the rectifier module, and a cathode of the third diode is connected to the power supply end of the load.

4. The power supply circuit according to claim 1, characterized in that: Also includes: A voltage stabilizing module, wherein the input end of the voltage stabilizing module is connected to the positive electrode of the super capacitor, and the output end is connected to the power supply end of the load, and is used to step down the input voltage of the voltage stabilizing module to a fixed voltage value.

5. The power supply circuit according to any one of claims 1 to 4, characterized in that: The power supply circuit is applied to an electric energy meter, and the battery comprises: a first battery, wherein the first battery is detachably disposed in the electric energy meter; a second battery, the second battery being fixedly disposed in the electric energy meter; The controllable switch comprises: A first controllable switch, wherein a first end of the first controllable switch is connected to the positive electrode of the first battery, and a second end of the first controllable switch is connected to the power supply end of the load, and is configured to be disconnected upon receiving a disconnection control signal, and to be turned on upon receiving a conduction control signal; a second controllable switch, wherein a first end of the second controllable switch is connected to the positive electrode of the second battery, and a second end of the second controllable switch is connected to the power supply end of the load; The power-off monitoring module comprises: A voltage acquisition module, wherein the input end of the voltage acquisition module is connected to the output end of the rectifier module, and the output end is connected to the input end of the first conversion module, and is used to collect the rectified voltage; The first conversion module, the output end of which is respectively connected to the first input end of the second conversion module and the control end of the first controllable switch, is used to output the disconnection control signal when the AC power supply is normally powered on, and output the conduction control signal when the AC power supply is powered off; The second conversion module, the second input end of the second conversion module is connected to the positive electrode of the first battery, and the output end is connected to the control end of the second controllable switch, and is used to control the second controllable switch to be disconnected when the disconnection control signal is received, control the second controllable switch to be disconnected when the conduction control signal is received and the voltage of the first battery is not less than the undervoltage value, and control the second controllable switch to be turned on when the conduction control signal is received and the voltage of the first battery is less than the undervoltage value.

6. The power supply circuit according to claim 5, characterized in that: The first conversion module comprises: A first switch tube, wherein the control end of the first switch tube is connected to the output end of the voltage acquisition module, the first end is connected to the first end of the second resistor, and the second end is grounded, and is used to be turned on when the AC power supply is normally powered on, and to be turned off when the AC power supply is powered off; The second resistor, a second end of the second resistor is connected to the direct current; a second switch tube, wherein the control end of the second switch tube is connected to the first end of the first switch tube, the first end is connected to the first end of the third resistor, and the second end is grounded, and is used to be disconnected when the first switch tube is turned on, and turned on when the first switch tube is turned off; The third resistor, a second end of the third resistor is connected to the direct current; A fourth resistor, wherein a first end of the fourth resistor is connected to the first end of the third resistor, and a second end of the fourth resistor is grounded.

7. The power supply circuit according to claim 6, characterized in that: The second conversion module comprises: a fourth diode, wherein an anode of the fourth diode is connected to the output end of the first conversion module, and a cathode of the fourth diode is connected to the input end of the power-off detection chip; a fifth diode, wherein an anode of the fifth diode is connected to the positive electrode of the first battery, and a cathode of the fifth diode is connected to the input end of the power-off detection chip; The power-off detection chip, the output end of the power-off detection chip is connected to the control end of the second controllable switch, and is used to control the second controllable switch to be disconnected when the disconnection control signal is received, control the second controllable switch to be disconnected when the conduction control signal is received and the voltage of the first battery is not less than the undervoltage value, and control the second controllable switch to be turned on when the conduction control signal is received and the voltage of the first battery is less than the undervoltage value.

8. The power supply circuit according to claim 6, characterized in that: The first conversion module also includes: A first capacitor, wherein a first end of the first capacitor is connected to the output end of the voltage acquisition module, and a second end of the first capacitor is grounded; a fifth resistor, wherein a first end of the fifth resistor is connected to the output end of the voltage acquisition module, and a second end of the fifth resistor is connected to the control end of the first switch tube; A second capacitor, wherein a first end of the second capacitor is connected to the first end of the second switch tube, and a second end thereof is grounded; A sixth resistor, wherein a first end of the sixth resistor is connected to the first end of the second switch tube, and a second end of the sixth resistor is connected to the first input end of the second conversion module.

9. The power supply circuit according to claim 7, characterized in that: The second conversion module also includes: a sixth diode, wherein an anode of the sixth diode is connected to the positive electrode of the first battery, and a cathode of the sixth diode is connected to the first end of the first controllable switch; A seventh diode, wherein an anode of the seventh diode is connected to the positive electrode of the second battery, and a cathode of the seventh diode is connected to the first end of the second controllable switch.

10. An electric energy meter, characterized in that: The invention comprises a power supply circuit as claimed in any one of claims 1 to 9, and further comprises a battery, wherein the battery is connected to the power supply circuit.

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