A new type of intelligent charging circuit for electric energy meter or collection terminal

Abstract

The utility model discloses a novel electric energy meter or collection terminal is with intelligent charging circuit, including voltage reducing module U4 and load VCAP, voltage reducing module U4 is provided with input terminal pin VIN, output terminal pin SW and feedback terminal pin FB, output terminal pin SW electric connection has energy storage inductance L5, energy storage inductance L5 is connected with access point VCC through the conducting wire, energy storage inductance L5 and access point VCC between have filter capacitor C30, filter capacitor C16 and filter capacitor EC8 in proper order, be provided with diode D25 between charging resistance and load VCAP. The utility model is provided with triode Q5, forms the clamping circuit through, and utilizes the VEB constant voltage difference of triode when power on, makes U4 output voltage be clamped and always exist fixed voltage difference with farad capacitor, and the power supply circuit is protected in the power-on instant, prevents charging current overload, guarantees the stable reliable normal operation of product, reduces the instantaneous impact to power grid simultaneously, makes the product effectively restrain the interference or influence to power grid.

Description

Technical Field

[0001] This utility model relates to the field of charging circuit technology, and in particular to a novel intelligent charging circuit for electricity meters or data acquisition terminals. Background Technology

[0002] An electricity meter is an instrument used to measure electrical energy, while a data acquisition concentrator is the central management and control device of a remote centralized meter reading system. It is responsible for functions such as periodically reading terminal data, transmitting system commands, data communication, network management, event logging, and horizontal data transmission. When using electricity meters or data acquisition terminals, backup power is generally set up to ensure that data and functions remain stable for a short period of time during sudden power outages, including normal terminal display and normal communication of the remote communication module. The existing backup power is generally achieved by using supercapacitors for automatic charging and discharging through charging circuits.

[0003] Depend on Figure 1 It is known that when a conventional circuit charges a supercapacitor, the voltage of supercapacitor EC9 and EC10 is 0V at the moment charging is started, and the supercapacitor is effectively short-circuited to ground. According to the capacitor charging voltage formula: Vt=V0+(VI-V0)×[1-exp(-t / RC)] and charging time t=RC×Ln[(V1-V0) / (V1-Vt)], where Vt is the voltage on the supercapacitor at time t, it can be seen from the formula that if the initial voltage V0 is 0, V1 is the charging voltage of 5V, the supercapacitor is 80F, and the design requires charging to 80% voltage (4V) in 10 minutes, then the resistance of the charging resistor R is about 0.2146Ω, and the minimum power of the resistor is about 116.4958W. To meet current resistance power requirements, charging resistors (Ra3, Ra4, Ra5) would need to be very large aluminum-cased resistors. Since aluminum-cased resistors are relatively expensive, this increases production costs. Furthermore, if conventional 1206-packaged 0.25W surface-mount resistors are used, the minimum resistance that can theoretically prevent them from burning out during charging is 100Ω. The large size of the charging resistors results in a long charging time to the supercapacitor voltage of 4V, which does not meet the usage requirements. In addition, the charging current overload at the moment of power-on can cause the energy meter and concentrator to reset. Therefore, there is room for further improvement. Utility Model Content

[0004] The purpose of this utility model is to at least solve one of the technical problems existing in the prior art, and to provide a new type of intelligent charging circuit for electricity meters or data acquisition terminals, thereby solving the above-mentioned problems.

[0005] To achieve the above objectives, a novel intelligent charging circuit for electricity meters or data acquisition terminals is provided, comprising a step-down module U4 and a load VCAP. The step-down module U4 has an input pin VIN, an output pin SW, and a feedback pin FB. The output pin SW is electrically connected to an energy storage inductor L5. The energy storage inductor L5 is connected to an access point VCC via a wire. A filter capacitor C30, a filter capacitor C16, and a filter capacitor EC8 are sequentially connected between the energy storage inductor L5 and the access point VCC. The access point VCC is connected to the load... A charging resistor is connected in series between VCAPs. A diode D25 is placed between the charging resistor and the load VCAP. Supercapacitors EC9 and EC10 are connected between the diode D25 and the load VCAP. A resistor R61 is connected between the energy storage inductor L5 and the filter capacitor C30. The feedback pin FB is connected in series with the resistor R61, and a grounding resistor R62 is connected between the feedback pin FB and the resistor R61. A transistor Q5 is connected in parallel across the charging resistor. The transistor Q5 has an emitter, a base, and a collector.

[0006] According to the novel smart charging circuit for an energy meter or data acquisition terminal, the emitter (E) of transistor Q5 is connected to the access point VCC, the base (B) of transistor Q5 is connected between the charging resistor and the diode D25, a current-limiting resistor R78 is connected in series with the base of transistor Q5, and a resistor R77 is connected in series with the collector (C) of transistor Q5 and is connected to the feedback pin FB through the resistor R77.

[0007] According to the novel smart charging circuit for an energy meter or data acquisition terminal, the charging resistors are resistors Ra3, Ra4, and Ra5 connected in parallel, and the resistance values ​​of resistors Ra3, Ra4, and Ra5 are all 2 ohms.

[0008] According to the novel smart charging circuit for an energy meter or data acquisition terminal, the supercapacitor EC9 and supercapacitor EC10 are connected in series, and the other end of supercapacitor EC10 is grounded.

[0009] According to the novel smart charging circuit for an energy meter or data acquisition terminal, the filter capacitors C30, C16, and EC8 are all grounded.

[0010] According to the novel smart charging circuit for an energy meter or data acquisition terminal, a capacitor C25 is connected in parallel with the resistor R61.

[0011] According to the novel smart charging circuit for an energy meter or data acquisition terminal, a capacitor C25 is connected in parallel with the resistor R61.

[0012] The above solution has at least one of the following beneficial effects:

[0013] 1. This utility model incorporates a transistor Q5, which connects to the original circuit and the parallel circuit. By forming a clamping circuit, the constant voltage difference of the transistor's VEB ensures that the output voltage of U4 is clamped and maintains a fixed voltage difference with the supercapacitor upon power-up. This protects the power supply circuit from charging current overload, ensuring stable and reliable normal operation of the product. Simultaneously, it reduces the instantaneous impact on the power grid, effectively suppressing interference or influence on the grid. The constant charging current is 0.87-1.02A, and the maximum instantaneous power is 0.5046-0.6936W. When the constant voltage difference of Q5 is 0.6V, the charging current is constant at 0.9A. When the supercapacitor charges from 0V to 4.4V, the charging time Δt = 391.1s, significantly shortening the capacitor charging time. This effectively achieves energy saving and emission reduction, enhancing the practicality of the device.

[0014] 2. This utility model can select three parallel 2Ω low-power current-limiting resistors Ra3, Ra4, and Ra5 in 1206 package, which is economical and practical. The charging resistor can be a conventional chip resistor. Compared with the existing aluminum shell resistors, it can effectively reduce costs, improve the market competitiveness of the product, and enhance the practicality of the device.

[0015] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0017] Figure 1 This is a charging circuit diagram for the original energy meter or data acquisition terminal of this utility model.

[0018] Figure 2 This is a circuit diagram of a novel intelligent charging circuit for an energy meter or data acquisition terminal according to this utility model. Detailed Implementation

[0019] This section will describe in detail the specific embodiments of the present utility model. Preferred embodiments of the present utility model are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present utility model. The drawings are all in a very simplified form and use non-precise proportions. They are only used to help to explain the embodiments of the present utility model in a convenient and clear way, and should not be construed as limiting the scope of protection of the present utility model.

[0020] Reference Figure 1-2This utility model provides a novel intelligent charging circuit for electricity meters or data acquisition terminals, including a step-down module U4 and a load VCAP. The step-down module U4 is a switching regulator with an input pin VIN, an output pin SW, an enable pin EN, a feedback pin FB, and a bootstrap pin BST. It provides a drive voltage to the internal high-side MOSFET via C27+R58 and simultaneously filters the input to suppress 12V pulse noise. The VIN input pin of the step-down module U4 is connected to a Q-F12V input voltage, and the output pin SW is electrically connected to an energy storage inductor L5. The step-down module U4 uses high-frequency switching to convert the 12V... The pulse is output through SW. The energy storage inductor L5 is connected to the access point VCC through a wire. Filter capacitors C30, C16, and EC8 are connected in sequence between the energy storage inductor L5 and the access point VCC. Filter capacitors C30, C16, and EC8 are all grounded to form a filter and rectifier circuit. The output is filtered to smooth the switching ripple and obtain a stable DC power supply, providing a stable 5.8V DC power to the access point VCC.

[0021] A charging resistor is connected in series between the access point VCC and the load VCAP. The charging resistor consists of resistors Ra3, Ra4, and Ra5 connected in parallel, and each of the resistors Ra3, Ra4, and Ra5 has a resistance of 2 ohms. A diode D25 is installed between the charging resistor and the load VCAP. Supercapacitors EC9 and EC10 are connected between the diode D25 and the load VCAP. Supercapacitors EC9 and EC10 are connected in series, and the other end of supercapacitor EC10 is grounded. This allows them to store electrical energy. When the power is off, supercapacitors EC9 and EC10 provide current to the load VCAP for backup power supply due to the function of diode D25.

[0022] A resistor R61 is connected between the energy storage inductor L5 and the filter capacitor C30. A capacitor C25 is connected in parallel with the resistor R61. The feedback pin FB is connected in series with the resistor R61 and a grounding resistor R62 is connected between the feedback pin FB and the resistor R61.

[0023] A transistor Q5, model 2SA812, is connected in parallel across the charging resistor. Transistor Q5 has an emitter (E), base (B), and collector (C) terminal. The VEB voltage drop of Q5 is a constant 0.58-0.68V. The emitter (E) terminal of transistor Q5 is connected to the connection point VCC. The base (B) terminal of transistor Q5 is connected between the charging resistor and diode D25. A current-limiting resistor R78 is connected in series with the base terminal of transistor Q5. A resistor R77 is connected in series with the collector terminal of transistor Q5 and is connected to the feedback pin FB through resistor R77.

[0024] Working Principle: In the initial power-on stage, Q5 conducts, and the output voltage of U4 is clamped, maintaining a fixed voltage difference with the supercapacitor, i.e., the voltage difference between E and B of Q5. A constant current charges the supercapacitors EC9 and EC10. Three 1206 low-power current-limiting resistors (Ra3, Ra4, Ra5) connected in parallel at 2Ω can be selected, providing a constant charging current of 0.87-1.02A and a maximum instantaneous power of 0.5046-0.6936W. According to the common formula for constant current charging and discharging: ΔVc=I*Δt / C, assuming a constant voltage difference of 0.6V for Q5, the charging current is constant at 0.9A. When the supercapacitor charges from 0V to 4.4V, the charging time Δt=391.1s. Once the supercapacitor exceeds 4.4V, the output voltage of U4 remains stable at 5V, and the charging current begins to decrease until the supercapacitor is fully charged. The charging time of the supercapacitor is significantly shortened, effectively achieving energy saving and emission reduction.

[0025] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. A novel intelligent charging circuit for electricity meters or data acquisition terminals, comprising a step-down module U4 and a load VCAP, characterized in that: The step-down module U4 has an input pin VIN, an output pin SW, and a feedback pin FB. The output pin SW is electrically connected to an energy storage inductor L5. The energy storage inductor L5 is connected to the access point VCC via a wire. Filter capacitors C30, C16, and EC8 are connected sequentially between the energy storage inductor L5 and the access point VCC. A charging resistor is connected in series between the load VCAP and the access point VCC. A diode D25 is placed between the charging resistor and the load VCAP. Supercapacitors EC9 and EC10 are connected between the diode D25 and the load VCAP. A resistor R61 is connected between the energy storage inductor L5 and the filter capacitor C30. The feedback pin FB is connected in series with the resistor R61, and a grounding resistor R62 is connected between the feedback pin FB and the resistor R61. A transistor Q5 is connected in parallel across the charging resistor. The transistor Q5 has an emitter (E), base (B), and collector (C) terminal.

2. The novel intelligent charging circuit for an energy meter or data acquisition terminal according to claim 1, characterized in that, The emitter (E) of transistor Q5 is connected to the access point VCC. The base (B) of transistor Q5 is connected between the charging resistor and diode D25. A current-limiting resistor R78 is connected in series with the base of transistor Q5. A resistor R77 is connected in series with the collector (C) of transistor Q5 and is connected to the feedback pin FB through the resistor R77.

3. The novel intelligent charging circuit for an energy meter or data acquisition terminal according to claim 1, characterized in that, The charging resistors are resistors Ra3, Ra4, and Ra5 connected in parallel, and the resistance values ​​of resistors Ra3, Ra4, and Ra5 are all 2 ohms.

4. The novel intelligent charging circuit for an energy meter or data acquisition terminal according to claim 1, characterized in that, The supercapacitor EC9 and supercapacitor EC10 are connected in series, and the other end of supercapacitor EC10 is grounded.

5. The novel intelligent charging circuit for an energy meter or data acquisition terminal according to claim 1, characterized in that, The filter capacitors C30, C16, and EC8 are all grounded.

6. The novel intelligent charging circuit for an energy meter or data acquisition terminal according to claim 1, characterized in that, The VIN input pin of the buck module U4 is connected to the Q-F12V input voltage.

7. The novel intelligent charging circuit for an energy meter or data acquisition terminal according to claim 1, characterized in that, A capacitor C25 is connected in parallel with the resistor R61.

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