A charging circuit capable of preventing an electric meter from resetting instantly upon power-on

Abstract

The present invention relates to a charging circuit capable of preventing an electric meter from resetting instantly when it is powered on, comprising a power module (1), an energy storage module (2) electrically connected to the power module (1), and a control module (3), and further comprising a switch module (4), wherein the switch module (4) is connected between the energy storage module (2) and the power module (1) and is connected to the control module (3); the control module (3) controls the switch module (4) to be non-conductive and performs a mains power detection when the electric meter is powered on, and controls the switch module (4) to be conductive when it is detected that the mains power is not less than a set value so that the power module (1) charges the energy storage module (2); and when it is detected that the mains power is less than the set value, maintains the switch module (4) to be non-conductive so that the energy storage module (2) is not charged. The present invention can effectively prevent the electric meter from resetting instantly when it is powered on.

Description

Technical Field

[0001] The invention relates to the technical field of electric energy meters, and in particular to a charging circuit capable of preventing an electric energy meter from being reset instantly when powered on. Background Art

[0002] With the development of industry, the operating environment of electric energy meters is becoming more and more complex. Under the condition of a normal power supply of 115V for low-voltage electric energy meters, the internal power supply load capacity is generally around 17.5mA, and the maximum current when the meter is powered on is about 15mA. After the supercapacitor inside the electric energy meter is charged for 2 hours, the current is almost equal to 0, which theoretically meets the design requirements. However, if the power supply voltage fluctuates at the moment of power-on, for example, when the power supply voltage is 100V, the power supply load capacity is also around 15mA, which is just about equal to the maximum current critical value when the meter is powered on, which may cause the meter power supply to overload and reset. Summary of the invention

[0003] In view of the above problems, an object of the present invention is to provide a charging circuit capable of preventing an electric meter from being reset instantly when powered on.

[0004] In order to achieve the above object, the technical solution of the present invention is: a charging circuit capable of preventing an electric meter from being reset instantly upon power-on, comprising a power module, an energy storage module electrically connected to the power module, and a control module, characterized in that:

[0005] It also includes a switch module, which is connected between the energy storage module and the power module and connected to the control module;

[0006] The control module controls the switch module to be non-conductive and performs AC power detection when the electric meter is powered on. When it is detected that the AC power is not less than the set value, the control module controls the switch module to be conductive so that the power module charges the energy storage module. When it is detected that the AC power is less than the set value, the switch module is maintained non-conductive so that the energy storage module is not charged.

[0007] Furthermore, the switch module includes a first switch submodule and a second switch submodule, the first switch submodule is connected to the control module, and the second switch submodule is connected between the power module and the energy storage module and is controlled to be on and off by the first switch submodule.

[0008] Further, the first switch submodule includes a first resistor, a second resistor and an NPN transistor;

[0009] One end of the first resistor is connected to the control module and the other end is connected to the base of the NPN transistor. The collector of the NPN transistor is connected to the second switch submodule and the emitter is grounded. The second resistor is connected between the emitter of the NPN transistor and the ground.

[0010] Furthermore, the second switch submodule includes a third resistor, a fourth resistor, a fifth resistor and a PNP transistor;

[0011] One end of the third resistor is connected to the power module and the other end is connected to the emitter of the PNP transistor. The base of the PNP transistor and the collector of the NPN transistor are connected through the fifth resistor. The fourth resistor is connected between the emitter and base of the PNP transistor.

[0012] Furthermore, the circuit also includes a sixth resistor connected to the energy storage module to limit current when the energy storage module is discharged.

[0013] Furthermore, the circuit also includes an anti-backflow diode connected between the collector of the PNP transistor and the energy storage module.

[0014] Furthermore, the energy storage module includes a super capacitor, one end of which is grounded and the other end of which is connected to a corresponding end of the anti-backflow diode.

[0015] Furthermore, the corresponding ends of the super capacitor and the anti-backflow diode are connected via a short-circuit plug.

[0016] Furthermore, the power supply module is a 5.2V DC power supply.

[0017] Furthermore, the set value is 115V.

[0018] Compared with the prior art, the advantages of the present invention are:

[0019] The circuit does not connect the supercapacitor to the circuit at the moment of power-on, but connects the supercapacitor to the circuit only when it detects that the mains power is greater than or equal to the set value. This avoids the problem of meter power overload that may be caused when the mains power does not reach the set value, thereby preventing the meter from resetting at the moment of power-on and improving the reliability of the meter. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a circuit diagram of a preferred embodiment of the present application. DETAILED DESCRIPTION

[0021] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0022] like Figure 1The circuit diagram of the preferred embodiment of the present application is shown. The charging circuit that can prevent the instantaneous reset of the electric meter when it is powered on includes a power module 1, an energy storage module 2 electrically connected to the power module 1, and a control module 3. The circuit also includes a switch module 4, which is connected between the energy storage module 2 and the power module 1 and connected to the control module 3; the control module 3 controls the switch module 4 to be non-conductive and performs a mains power detection when the electric meter is powered on. When it is detected that the mains power is not less than the set value, the switch module 4 is controlled to be conductive so that the power module 1 charges the energy storage module 2, and when it is detected that the mains power is less than the set value, the switch module 4 is maintained non-conductive so that the energy storage module 2 is not charged. In this embodiment, the power module is a 5.2V DC power supply, the set value is 115V, and the control module is an MCU.

[0023] like Figure 1 As shown, the switch module 4 includes a first switch submodule 41 and a second switch submodule 42. The first switch submodule 41 is connected to the control module 3. The second switch submodule 42 is connected between the power module 1 and the energy storage module 2 and is controlled to be on and off by the first switch submodule 41. The first switch submodule 41 includes a first resistor R1, a second resistor R2 and an NPN transistor V1. One end of the first resistor R1 is connected to the control module 3 and the other end is connected to the base of the NPN transistor V1. The collector of the NPN transistor V1 is connected to the second switch submodule 42 and the emitter is grounded. The second resistor R2 is connected between the emitter of the NPN transistor V1 and the ground.

[0024] The second switch submodule 42 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5 and a PNP transistor V2, one end of the third resistor R3 is connected to the power module 1 and the other end is connected to the emitter of the PNP transistor V2, the base of the PNP transistor V2 and the collector of the NPN transistor V1 are connected through the fifth resistor R5, and the fourth resistor R4 is connected between the emitter and the base of the PNP transistor V2.

[0025] The charging circuit can supply power to the load end of the meter through the energy storage module when the meter loses power, and in order to ensure the safety of the circuit, the circuit also includes a sixth resistor R6 connected to the energy storage module 2 to limit the current when the energy storage module 2 is discharged. At the same time, the circuit also includes an anti-backflow diode VD1 connected between the collector of the PNP transistor V2 and the energy storage module 2.

[0026] Preferably, the energy storage module 2 includes a super capacitor C9, one end of which is grounded and the other end is connected to the corresponding end of the backflow protection diode VD1. At the same time, the super capacitor C9 is connected to the corresponding end of the backflow protection diode VD1 through a shorting point plug JP1.

[0027] The principle of this charging circuit to prevent the meter from resetting at the moment of power-on is as follows:

[0028] When the meter is powered on, the corresponding I / O port of the MCU outputs a low level, making CAPCON = 0, the NPN transistor V1 is turned off, the PNP transistor V2 is turned off, and the supercapacitor C9 does not perform a charging operation. At the same time, the MCU first detects the mains voltage that powers the meter.

[0029] When it is detected that the mains power is greater than or equal to 115V, the I / O port corresponding to the MCU outputs a high level, CAPCON = 1, the NPN transistor V1 is turned on, and the PNP transistor V2 is also turned on to charge the supercapacitor C9;

[0030] When it is detected that the mains power is less than 115V, the corresponding I / O port of the MCU outputs a low level, CAPCON=0, the NPN transistor V1 is cut off, the PNP transistor V2 is cut off, and the supercapacitor C9 stops charging.

[0031] If the mains voltage fluctuates, for example, when the mains voltage is 100V, the power load capacity of the meter is about 15mA. Due to the design of the charging circuit, the supercapacitor C9 is not charged at the moment of power-on, that is, the charging current of the supercapacitor C9 is 0, so that the maximum current of the meter at the moment of power-on is about 11mA, which is less than the maximum load current of the meter. The meter will not reset, so it fully meets the design requirements.

[0032] Although embodiments of the present invention have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A charging circuit capable of preventing an electric meter from resetting instantaneously when powered on, comprising a power module (1), an energy storage module (2) electrically connected to the power module (1), and a control module (3), characterized in that: It also includes a switch module (4), wherein the switch module (4) is connected between the energy storage module (2) and the power supply module (1) and is connected to the control module (3); The control module (3) controls the switch module (4) to be non-conductive and performs a mains power detection when the electric meter is powered on. When it is detected that the mains power is not less than a set value, the switch module (4) is controlled to be conductive so that the power module (1) charges the energy storage module (2). When it is detected that the mains power is less than the set value, the switch module (4) is maintained non-conductive so that the energy storage module (2) is not charged. The switch module (4) comprises a first switch submodule (41) and a second switch submodule (42), wherein the first switch submodule (41) is connected to the control module (3), and the second switch submodule (42) is connected between the power module (1) and the energy storage module (2) and is controlled to be on and off by the first switch submodule (41); The first switch submodule (41) comprises a first resistor (R1), a second resistor (R2) and an NPN transistor (V1); One end of the first resistor (R1) is connected to the control module (3) and the other end is connected to the base of the NPN transistor (V1); the collector of the NPN transistor (V1) is connected to the second switch submodule (42) and the emitter is grounded; the second resistor (R2) is connected between the emitter of the NPN transistor (V1) and the ground; The second switch submodule (42) comprises a third resistor (R3), a fourth resistor (R4), a fifth resistor (R5) and a PNP-type transistor (V2); One end of the third resistor (R3) is connected to the power module (1) and the other end is connected to the emitter of the PNP transistor (V2); the base of the PNP transistor (V2) is connected to the collector of the NPN transistor (V1) via a fifth resistor (R5); and the fourth resistor (R4) is connected between the emitter and the base of the PNP transistor (V2).

2. The charging circuit according to claim 1, characterized in that: The circuit also includes a sixth resistor (R6) connected to the energy storage module (2) for limiting current when the energy storage module (2) is discharging.

3. The charging circuit according to claim 1, characterized in that: The circuit also includes an anti-backflow diode (VD1) connected between the collector of the PNP transistor (V2) and the energy storage module (2).

4. The charging circuit according to claim 3, characterized in that: The energy storage module (2) comprises a super capacitor (C9), one end of the super capacitor (C9) is grounded and the other end is connected to the corresponding end of the anti-backflow diode (VD1).

5. The charging circuit according to claim 4, characterized in that: The super capacitor (C9) is connected to the corresponding end of the backflow prevention diode (VD1) through a shorting point plug (JP1).

6. The charging circuit according to claim 1, characterized in that: The power supply module (1) is a 5.2V DC power supply.

7. The charging circuit according to claim 1, characterized in that: The set value is 115V.

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