Direct-current anti-reverse-connection two-way metering circuit
By adding a resistive voltage divider circuit and a shunt at the positive and negative terminals of the DC meter, the overvoltage problem of the metering chip caused by wiring errors is solved, and the bidirectional metering and anti-reverse connection functions are realized, which improves the stability and fault tolerance of measurements. .
Patent Information
- Application Number
- CN202323513808.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-21
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2033-12-21
AI Technical Summary
Existing DC metering can easily cause overvoltage and burning of the metering chip when wiring is incorrect, and cannot support bidirectional metering and anti-reverse connection.
A DC anti-reverse bidirectional metering circuit is designed. By adding a resistive voltage divider at both positive and negative terminals, high reliability measurement can be achieved. Even if the voltage detection is reversed, it can be measured normally. A shunt is used in the current acquisition part. Ensure the current path is stable.
The power measurement with high reliability and high fault tolerance is achieved, and abnormal situations caused by reverse connection are avoided, ensuring the stability and accuracy of the measurement.
Smart Images
Figure CN222167116U_ABST
Abstract
Description
Technical Field
[0001] The utility model embodiment relates to the technical field of direct current meters, and in particular to a direct current reverse connection prevention bidirectional metering circuit. Background Art
[0002] Due to the advantages of DC power, the current DC power distribution network is becoming more and more widely used, especially in the new energy era. More and more DC meters are used in charging stations and charging piles, but most DC meters only support fixed wiring. If the wiring is reversed, it will not work (that is, it does not support bidirectional measurement) or burn the meter. Therefore, a measurement circuit that can meet bidirectional measurement and reverse connection protection is particularly important.
[0003] like Figure 1 As shown, in the prior art, direct current is connected to the meter body through terminals P2 and P5. Figure 2 The circuit in the figure cooperates with the metering chip U6 to realize the voltage measurement. P2 is connected to the positive pole and P5 is connected to the negative pole. If the external wiring is wrong, that is, P2 is connected to the negative pole and P5 is connected to the positive pole, then the external high voltage will be directly added to the input port of the metering chip, causing the chip to burn out due to overvoltage. Therefore, a measurement circuit that can meet the requirements of bidirectional measurement and reverse connection protection is urgently needed. Utility Model Content
[0004] The embodiment of the utility model provides a DC reverse connection protection bidirectional metering circuit, which solves the technical problem that if the external wiring is wrong, such as the positive and negative poles are reversed, the external high voltage will be directly added to the input port of the metering chip, causing the chip to be over-voltage and burned.
[0005] The utility model embodiment provides a DC reverse connection prevention bidirectional metering circuit, including: a voltage acquisition circuit, a current acquisition circuit, and a metering chip circuit; wherein:
[0006] The voltage acquisition circuit includes a port P1, N resistors connected in series, a resistor R11, and a capacitor C1; wherein the port P1 is externally connected to the positive or negative electrode of the DC voltage input terminal, and internally connected to one end of the N resistors connected in series, the other end of the N resistors connected in series is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the power supply VSS, and the capacitor C1 is connected to both ends of the resistor R11;
[0007] The voltage acquisition circuit also includes a port P2, N resistors connected in series, a resistor R22, and a capacitor C2; wherein the port P2 is externally connected to the positive or negative electrode of the DC voltage input terminal, and internally connected to one end of the N resistors connected in series, the other end of the N resistors connected in series is connected to one end of the resistor R22, the other end of the resistor R22 is connected to the power supply VSS, and the capacitor C2 is connected to both ends of the resistor R22;
[0008] The current acquisition circuit includes a port P3, a port P4, a resistor R24, a resistor R25, a TVS diode, a resistor R23, a capacitor C3, a resistor R26, and a capacitor C4; wherein, the port P3 and the port P4 are externally connected to the two ends of the shunt connected in series with the load, the port P3 is internally connected to one end of the resistor R24, the port P4 is internally connected to one end of the resistor R25, the other end of the resistor R24 is connected to the other end of the resistor R25 and connected to the power supply VSS, the two ends of the TVS diode are connected to one end of the resistor R24 and one end of the resistor R25, one end of the resistor R23 is connected to one end of the resistor R24, the other end of the resistor R23 is connected to one end of the capacitor C3, one end of the resistor R26 is connected to one end of the resistor R25, the other end of the resistor R26 is connected to one end of the capacitor C4, the other end of the capacitor C3 is connected to the other end of the capacitor C4 and connected to the power supply VSS;
[0009] The metering chip circuit includes a metering chip U1, a capacitor C5, a capacitor C6, a capacitor C7, and a crystal oscillator Y1; wherein one end of the capacitor C5 is connected to the DVDD pin of the chip U1, the other end of the capacitor C5 is connected to the power supply VSS, the DVDD pin of the chip U1 is further connected to the power supply DVCC, one end of the capacitor C6 is connected to the OSCO pin of the chip U1, the other end of the capacitor C6 is connected to the power supply VSS, one end of the capacitor C7 is connected to the OSCI pin of the chip U1, the other end of the capacitor C7 is connected to the power supply VSS, the 1st The first and second pins are respectively connected to one end of capacitor C6 and one end of capacitor C7, the third pin of crystal oscillator Y1 is connected to the power supply VSS, the V3P pin of chip U1 is connected to one end VI+ of resistor R11, the V3N pin of chip U1 is connected to one end VI- of resistor R22, the V1P pin of chip U1 is connected to one end IL+ of capacitor C3, the V1N pin of chip U1 is connected to one end IL- of capacitor C4, the AVDD pin of chip U1 is connected to the power supply AVCC, and the DGND pin of chip U1 is connected to the power supply VSS.
[0010] Furthermore, the value of N is associated with the voltage value of the DC voltage input terminal and the withstand voltage value of each resistor.
[0011] Furthermore, N is 10.
[0012] Furthermore, the resistor R25 is a 0 ohm resistor.
[0013] The technical solution of the embodiment of the utility model achieves high reliability by adding a resistor voltage divider circuit at both the positive and negative terminals. Even if the voltage detection is connected reversely, it can still be measured normally. At the same time, the installation fault tolerance rate is high. Even if the connection is reversed, there will be no abnormality, and the installation fault tolerance rate is high. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a circuit diagram of the wiring method of the prior art;
[0015] Figure 2 is a circuit schematic diagram of a measuring circuit of the prior art;
[0016] Figure 3 It is a circuit schematic diagram of a voltage acquisition circuit in an embodiment of the utility model;
[0017] Figure 4 It is a circuit schematic diagram of the current collection circuit in the embodiment of the utility model;
[0018] Figure 5 It is a circuit principle diagram of the metering chip circuit in the embodiment of the utility model. DETAILED DESCRIPTION
[0019] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.
[0020] It should be mentioned before discussing the exemplary embodiments in more detail that some exemplary embodiments are described as processes or methods depicted as flow charts. Although the flow charts describe the steps as sequential processes, many of the steps therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of the steps can be rearranged. The process can be terminated when its operation is completed, but can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.
[0021] In addition, the terms "first", "second", etc. can be used in this article to describe various directions, actions, steps or elements, but these directions, actions, steps or elements are not limited by these terms. These terms are only used to distinguish a first direction, action, step or element from another direction, action, step or element. For example, without departing from the scope of the present application, the first speed difference can be referred to as the second speed difference, and similarly, the second speed difference can be referred to as the first speed difference. Both the first speed difference and the second speed difference are speed differences, but they are not the same speed difference. The terms "first", "second", etc. cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.
[0022] Reference Figure 3 ,4 5. The DC reverse connection protection bidirectional metering circuit of the utility model embodiment specifically includes: a voltage acquisition circuit ( Figure 3 )、Current acquisition circuit( Figure 4 )、Metering chip circuit( Figure 5 );in:
[0023] The voltage acquisition circuit includes a port P1, N resistors connected in series, a resistor R11, and a capacitor C1; wherein the port P1 is externally connected to the positive or negative electrode of the DC voltage input terminal, and internally connected to one end of the N resistors connected in series, the other end of the N resistors connected in series is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the power supply VSS, and the capacitor C1 is connected to both ends of the resistor R11;
[0024] The voltage acquisition circuit also includes a port P2, N resistors connected in series, a resistor R22, and a capacitor C2; wherein the port P2 is externally connected to the positive or negative electrode of the DC voltage input terminal, and internally connected to one end of the N resistors connected in series, the other end of the N resistors connected in series is connected to one end of the resistor R22, the other end of the resistor R22 is connected to the power supply VSS, and the capacitor C2 is connected to both ends of the resistor R22;
[0025] The value of N of the N resistors connected in series is associated with the voltage value of the DC voltage input terminal and the withstand voltage value of each resistor. For example, if the voltage value of the DC voltage input terminal is 1000V and the withstand voltage value of each resistor is 500V, at least two voltage-dividing resistors need to be connected in series to ensure that the resistors will not be burned. In this embodiment, the value of N is 10, that is, 10 resistors are connected in series in sequence.
[0026] The current acquisition circuit includes a port P3, a port P4, a resistor R24, a resistor R25, a TVS diode, a resistor R23, a capacitor C3, a resistor R26, and a capacitor C4; wherein, the port P3 and the port P4 are externally connected to the two ends of the shunt connected in series with the load, the port P3 is internally connected to one end of the resistor R24, the port P4 is internally connected to one end of the resistor R25, the other end of the resistor R24 is connected to the other end of the resistor R25 and connected to the power supply VSS, the two ends of the TVS diode are connected to one end of the resistor R24 and one end of the resistor R25, one end of the resistor R23 is connected to one end of the resistor R24, the other end of the resistor R23 is connected to one end of the capacitor C3, one end of the resistor R26 is connected to one end of the resistor R25, the other end of the resistor R26 is connected to one end of the capacitor C4, the other end of the capacitor C3 is connected to the other end of the capacitor C4 and connected to the power supply VSS;
[0027] The metering chip circuit includes a metering chip U1, a capacitor C5, a capacitor C6, a capacitor C7, and a crystal oscillator Y1; wherein one end of the capacitor C5 is connected to the DVDD pin of the chip U1, the other end of the capacitor C5 is connected to the power supply VSS, the DVDD pin of the chip U1 is further connected to the power supply DVCC, one end of the capacitor C6 is connected to the OSCO pin of the chip U1, the other end of the capacitor C6 is connected to the power supply VSS, one end of the capacitor C7 is connected to the OSCI pin of the chip U1, the other end of the capacitor C7 is connected to the power supply VSS, the 1st The first and second pins are respectively connected to one end of capacitor C6 and one end of capacitor C7, the third pin of crystal oscillator Y1 is connected to the power supply VSS, the V3P pin of chip U1 is connected to one end VI+ of resistor R11, the V3N pin of chip U1 is connected to one end VI- of resistor R22, the V1P pin of chip U1 is connected to one end IL+ of capacitor C3, the V1N pin of chip U1 is connected to one end IL- of capacitor C4, the AVDD pin of chip U1 is connected to the power supply AVCC, and the DGND pin of chip U1 is connected to the power supply VSS.
[0028] In this embodiment, the voltage acquisition part is realized by using a voltage-dividing resistor, but this design already has the function of positive and negative connection (anti-reverse connection). For example, if the positive end of the voltage is connected to the P1 terminal, the voltage VI+ is obtained by voltage division through R1-R11 and sent to the differential input terminal of the metering chip. The negative end of the voltage is connected to the P2 terminal. At this time, the return path of the current is from R22 through VSS, and then through R25 and terminal P4 back to the negative end of the voltage. Conversely, if the positive end of the voltage is connected to the P2 terminal, the voltage VI- is obtained by voltage division through R12-R22 and sent to the differential input terminal of the metering chip. The negative end of the voltage is connected to the P4 terminal. At this time, the return path of the current is from R22 through VSS, and then through R25 and terminal P4 back to the negative end of the voltage.
[0029] Taking P1 as the positive electrode and P2 as the negative electrode as an example, R1-R11 are connected in series. Figure 3 The voltage is divided at point A to get VI+, and then it passes through a similar circuit from the terminal of P5. Figure 3 The voltage is divided at point B to obtain VI-, and then these two voltages are sent to the metering chip to calculate the voltage information.
[0030] Taking P1 as the negative electrode and P2 as the positive electrode as an example, R1-R11 are connected in series. Figure 3 The voltage is divided at point A to get VI+, and then it passes through a similar circuit from the terminal of P5. Figure 3 The voltage is divided at point B to obtain VI-, and then the two voltages are sent to the metering chip to calculate the voltage information. At this time, because the direction is different from the preset voltage, the voltage measurement value obtained at this time is negative, which realizes bidirectional measurement.
[0031] In this embodiment, the current collection part is realized by using a shunt. Considering the insulation safety, the shunt needs to be connected to the negative end of the voltage, such as Figure 1 As shown, P3 is connected to the back end of the load, and P4 is connected to the negative pole of the power supply. They are connected to the metering chip after passing through a low-pass filter. Since the resistance of the shunt does not change, the current value can be obtained by dividing the voltage by the resistance of the shunt. Among them, the function of the low-pass filter is to filter out high-frequency interference signals and retain low-frequency DC signals.
[0032] It should be noted that in order to ensure that the positive and negative connection of the voltage does not affect the measurement accuracy, R25 is added to add a low impedance loop to the current. Because no matter whether the negative end of the voltage is connected to P1 or P2, it must pass through 10 series resistors (R1-R11 or R12-R22), and its resistance reaches the megohm level. In order to avoid the problem of high impedance of the negative pole caused by this connection method, it is necessary to Figure 4 Replace R25 with a low resistance resistor or a 0 ohm resistor, and take P1 as the positive electrode and P2 as the negative electrode as an example. Figure 3 It can be seen that P2 should be kept at the same potential as the negative electrode of the measured input voltage as much as possible, so that there should be no high impedance between V- and the negative electrode of the input voltage, otherwise once there is an interference signal, a voltage difference will be formed at the measurement end, affecting the measurement effect. Figure 4 If R25 in the measurement is large, the current path at the measuring end will follow Figure 3 The R12-R21 path in the circuit returns to the negative pole of the input voltage. Obviously, R12-R21 forms a high impedance of up to 2.5MΩ, which has a great influence on the stability of the measurement. Figure 4 If R25 in the circuit is replaced with a 0Ω resistor, the current path at the measuring end will be as follows Figure 3 , Figure 4 The R22-VSS-R25-P4 path in the circuit returns to the negative pole of the input voltage, with almost no impedance, and has no effect on the stability of the measurement.
[0033] The technical solution of the embodiment of the utility model achieves high reliability by adding a resistor voltage divider circuit at both the positive and negative terminals. Even if the voltage detection is connected reversely, it can still be measured normally. At the same time, the installation fault tolerance rate is high. Even if the connection is reversed, there will be no abnormality, and the installation fault tolerance rate is high.
[0034] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention is described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims
1. A DC reverse connection prevention bidirectional metering circuit, characterized in that: include: Voltage acquisition circuit, current acquisition circuit, metering chip circuit; wherein: The voltage acquisition circuit includes a port P1, N resistors connected in series, a resistor R11, and a capacitor C1; wherein the port P1 is externally connected to the positive or negative electrode of the DC voltage input terminal, and internally connected to one end of the N resistors connected in series, the other end of the N resistors connected in series is connected to one end of the resistor R11, the other end of the resistor R11 is connected to the power supply VSS, and the capacitor C1 is connected to both ends of the resistor R11; The voltage acquisition circuit also includes a port P2, N resistors connected in series, a resistor R22, and a capacitor C2; wherein the port P2 is externally connected to the positive or negative electrode of the DC voltage input terminal, and internally connected to one end of the N resistors connected in series, the other end of the N resistors connected in series is connected to one end of the resistor R22, the other end of the resistor R22 is connected to the power supply VSS, and the capacitor C2 is connected to both ends of the resistor R22; The current acquisition circuit includes a port P3, a port P4, a resistor R24, a resistor R25, a TVS diode, a resistor R23, a capacitor C3, a resistor R26, and a capacitor C4; wherein, the port P3 and the port P4 are externally connected to the two ends of the shunt connected in series with the load, the port P3 is internally connected to one end of the resistor R24, the port P4 is internally connected to one end of the resistor R25, the other end of the resistor R24 is connected to the other end of the resistor R25 and connected to the power supply VSS, the two ends of the TVS diode are connected to one end of the resistor R24 and one end of the resistor R25, one end of the resistor R23 is connected to one end of the resistor R24, the other end of the resistor R23 is connected to one end of the capacitor C3, one end of the resistor R26 is connected to one end of the resistor R25, the other end of the resistor R26 is connected to one end of the capacitor C4, the other end of the capacitor C3 is connected to the other end of the capacitor C4 and connected to the power supply VSS; The metering chip circuit includes a metering chip U1, a capacitor C5, a capacitor C6, a capacitor C7, and a crystal oscillator Y1; wherein one end of the capacitor C5 is connected to the DVDD pin of the chip U1, the other end of the capacitor C5 is connected to the power supply VSS, the DVDD pin of the chip U1 is further connected to the power supply DVCC, one end of the capacitor C6 is connected to the OSCO pin of the chip U1, the other end of the capacitor C6 is connected to the power supply VSS, one end of the capacitor C7 is connected to the OSCI pin of the chip U1, the other end of the capacitor C7 is connected to the power supply VSS, the 1st The first and second pins are respectively connected to one end of capacitor C6 and one end of capacitor C7, the third pin of crystal oscillator Y1 is connected to the power supply VSS, the V3P pin of chip U1 is connected to one end VI+ of resistor R11, the V3N pin of chip U1 is connected to one end VI- of resistor R22, the V1P pin of chip U1 is connected to one end IL+ of capacitor C3, the V1N pin of chip U1 is connected to one end IL- of capacitor C4, the AVDD pin of chip U1 is connected to the power supply AVCC, and the DGND pin of chip U1 is connected to the power supply VSS.
2. The DC reverse connection prevention bidirectional metering circuit according to claim 1, characterized in that: The value of N is related to the voltage value of the DC voltage input terminal and the withstand voltage value of each resistor.
3. The DC reverse connection prevention bidirectional metering circuit according to claim 1, characterized in that: N is 10.
4. The DC reverse connection prevention bidirectional metering circuit according to claim 1, characterized in that: Resistor R25 is a 0 ohm resistor.