Anti-low-frequency interference power-off control device for intelligent water meter

Abstract

The utility model provides an anti-low-frequency interference power-off control device for an intelligent water meter. The anti-low-frequency interference power-off control device comprises a power supply control circuit, a detection circuit and a detection control circuit, the input end of the power supply control circuit is connected to a power supply of the intelligent water meter, and the output end supplies power to a load of the intelligent water meter; the detection circuit is used for detecting low-frequency interference of the environment where the intelligent water meter is located and outputting a control signal under the low-frequency interference; the input end of the detection control circuit is connected to the output end of the detection circuit, the output end of the detection control circuit is connected to the control end of the power supply control circuit, and the detection control circuit is used for outputting high level to the control end of the power supply control circuit when the detection circuit outputs the control signal and turning off a power supply loop of the power supply control circuit through the high level.

Description

Technical Field

[0001] This utility model relates to a smart water meter protection device, and more particularly to a smart water meter anti-low frequency interference power-off control device. Background Technology

[0002] Smart water meters are widely used because they can perform real-time data collection and uploading, thus enabling automatic meter reading. However, smart water meters also have their own drawbacks, such as being susceptible to interference, namely electromagnetic interference.

[0003] In existing technologies, to prevent unauthorized interference with smart water meters through electromagnetic interference (EMC), such as data modification, various EMC prevention measures are employed, including the use of shielding shells. While shielding shells offer some protection against EMC, they are generally more effective against high-frequency interference, providing stronger attenuation. However, for low-frequency, high-power EMC, the shielding shell can offer some protection if the interference is weak. But against high-power, low-frequency EMC, its effectiveness is less pronounced. This is because low-frequency EMC has strong penetrating power, and at high power, the diffraction of electromagnetic signals weakens the shielding shell's attenuation of low-frequency EMC. Furthermore, low-frequency EMC is not only used for data modification; more importantly, it can cause sensor misalignment during operation, severely affecting measurement accuracy and even damaging the sensor.

[0004] Therefore, in order to solve the above-mentioned technical problems, it is urgent to propose a new technical approach. Utility Model Content

[0005] In view of this, the purpose of this utility model is to provide a smart water meter anti-low frequency interference power-off control device, which can detect low frequency electromagnetic interference when unauthorized users use it, and can disconnect the power supply circuit between the smart water meter power supply and each load in a timely manner, so that the electrical components of the smart water meter are in a power-off state under low frequency electromagnetic interference, thereby forming a good protection, especially preventing the smart water meter sensor from being irreversibly damaged by low frequency electromagnetic interference when powered on.

[0006] This utility model provides a smart water meter anti-low frequency interference power-off control device, which includes a power supply control circuit, a detection circuit, and a detection control circuit.

[0007] The power supply control circuit has its input terminal connected to the power supply of the smart water meter, and its output terminal supplying power to the load of the smart water meter.

[0008] The detection circuit is used to detect low-frequency interference in the environment where the smart water meter is located and output a control signal under low-frequency interference.

[0009] The detection control circuit has its input terminal connected to the output terminal of the detection circuit and its output terminal connected to the control terminal of the power supply control circuit. It is used to output a high level to the control terminal of the power supply control circuit when the detection circuit outputs a control signal and to turn off the power supply circuit of the power supply control circuit through the high level.

[0010] Furthermore, the power supply control circuit includes a PMOS transistor Q1, resistors R7, R8, R9, R10, R11, diode D1, transistor T3, and a self-resetting manual switch SW1.

[0011] The source of PMOS transistor Q1 is connected to the power supply of the smart water meter as the input terminal of the power supply control circuit. The drain of PMOS transistor is connected to the positive terminal of diode D1. The negative terminal of diode D1 is used as the output terminal of the power supply control circuit to supply power to the load RL.

[0012] One end of resistor R7 is connected to the source of PMOS transistor Q1, and the other end of resistor R7 is connected to the gate of PMOS transistor Q1. The gate of PMOS transistor Q1 is connected to the collector of transistor T3 through resistor R9. The emitter of transistor T3 is grounded. The drain of PMOS transistor Q1 is grounded through resistors R10 and R11 connected in series. The common connection point between resistors R10 and R11 is connected to the base of transistor T3. The drain of PMOS transistor Q1 is grounded through capacitor C4. One end of the self-reset manual switch SW1 is connected to the source of PMOS transistor Q1, and the other end of the self-reset manual switch is connected to the common ground between the drain of PMOS transistor Q1 and capacitor C4 through resistor R8. The gate of PMOS transistor Q1 serves as the control terminal of the power supply control circuit.

[0013] Furthermore, the detection circuit includes an antenna ANT, a low-pass filter circuit, a diode D2, and a comparator circuit;

[0014] The output terminal of the antenna ANT is connected to the input terminal of the low-pass filter circuit. The output terminal of the low-pass filter circuit is connected to the positive terminal of the diode D2. The negative terminal of the diode D2 is grounded through the capacitor C2. The negative terminal of the diode D2 is connected to the input terminal of the comparator circuit. The output terminal of the comparator circuit serves as the output terminal of the detection circuit.

[0015] Furthermore, the low-pass filter circuit includes capacitor C1, capacitor C5, and inductor L1;

[0016] One end of capacitor C1 is connected to the output terminal of antenna ANT, and the other end of capacitor C1 is grounded. The common connection point between capacitor C1 and antenna ANT is connected to one end of inductor L1, and the other end of inductor L1 is grounded through capacitor C5. The common connection point between inductor L1 and capacitor C5 serves as the output terminal of the low-pass filter circuit.

[0017] Furthermore, the comparison circuit includes a comparator U1, resistors R1, R2, R3, and R4;

[0018] The non-inverting input of comparator U1 is connected to one end of resistor R1, and the other end of resistor R1 serves as the input of the comparator circuit. One end of resistor R3 is connected to the output of the power supply control circuit, and the other end of resistor R3 is grounded through resistor R2. The common connection point between resistors R2 and R3 is connected to the inverting input of comparator U1. The output of comparator U1 is connected to one end of resistor R4, and the other end of resistor R4 serves as the output of the comparator circuit.

[0019] Furthermore, the comparison circuit also includes a capacitor C3, one end of which is connected to the resistor R4 as one end of the output terminal of the comparison circuit, and the other end of the capacitor C3 is grounded.

[0020] Furthermore, the detection control circuit includes transistor T1, transistor T2, and resistor R6;

[0021] The emitter of transistor T1 is connected to the source of PMOS transistor Q1. The collector of transistor T1 serves as the control output of the detection and control circuit. The base of transistor T1 is connected to the source of PMOS transistor Q1. The collector of transistor T2 is connected to the base of transistor T1 through resistor R6. The emitter of transistor T2 is grounded. The base of transistor T2 serves as the input of the detection and control circuit.

[0022] Among them, transistor T1 is a P-type transistor.

[0023] The beneficial effects of this utility model are as follows: This utility model can detect low-frequency electromagnetic interference when unauthorized parties use it, and can promptly disconnect the power supply circuit between the smart water meter power supply and each load, thereby keeping the electrical components of the smart water meter in a power-off state under low-frequency electromagnetic interference, thus forming good protection, especially preventing irreversible damage to the smart water meter's sensors caused by low-frequency electromagnetic interference when powered on. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0025] Figure 1 This is a schematic diagram of the structure of this utility model.

[0026] Figure 2 This is the circuit schematic diagram of this utility model. Detailed Implementation

[0027] The present invention will be further described in detail below:

[0028] This utility model provides a smart water meter anti-low frequency interference power-off control device, which includes a power supply control circuit, a detection circuit, and a detection control circuit.

[0029] The power supply control circuit has its input terminal connected to the power supply of the smart water meter, and its output terminal supplying power to the load of the smart water meter.

[0030] The detection circuit is used to detect low-frequency interference in the environment where the smart water meter is located and output a control signal under low-frequency interference.

[0031] The detection and control circuit has its input terminal connected to the output terminal of the detection circuit and its output terminal connected to the control terminal of the power supply control circuit. It outputs a high-level signal to the control terminal of the power supply control circuit when the detection circuit outputs a control signal, thereby shutting off the power supply circuit of the power supply control circuit. This structure enables the detection of low-frequency electromagnetic interference even when unauthorized parties use it, and allows for timely disconnection of the power supply circuit between the smart water meter's power supply and each load. This ensures that the smart water meter's electrical components are de-energized under low-frequency electromagnetic interference, providing effective protection, especially preventing irreversible damage to the smart water meter's sensors from low-frequency electromagnetic interference while the meter is powered on.

[0032] In this embodiment, the power supply control circuit includes a PMOS transistor Q1, resistors R7, R8, R9, R10, R11, diode D1, transistor T3, and a self-resetting manual switch SW1.

[0033] The source of PMOS transistor Q1 is connected to the power supply of the smart water meter as the input terminal of the power supply control circuit. The drain of PMOS transistor is connected to the positive terminal of diode D1. The negative terminal of diode D1 is used as the output terminal of the power supply control circuit to supply power to the load RL.

[0034] One end of resistor R7 is connected to the source of PMOS transistor Q1, and the other end of resistor R7 is connected to the gate of PMOS transistor Q1. The gate of PMOS transistor Q1 is connected to the collector of transistor T3 through resistor R9. The emitter of transistor T3 is grounded. The drain of PMOS transistor Q1 is grounded through resistors R10 and R11 connected in series. The common connection point between resistors R10 and R11 is connected to the base of transistor T3. The drain of PMOS transistor Q1 is grounded through capacitor C4. One end of the self-reset manual switch SW1 is connected to the source of PMOS transistor Q1, and the other end of the self-reset manual switch is connected to the common ground between the drain of PMOS transistor Q1 and capacitor C4 through resistor R8. The gate of PMOS transistor Q1 serves as the control terminal of the power supply control circuit. Smart water meters are generally powered by batteries. However, when conditions permit, online power supply can be used, which involves rectifying and stepping down the AC mains voltage to generate the required DC power. In this structure, during initial power-up, simply pressing the self-reset switch SW1 activates the circuit containing resistor R8, charging capacitor C4. As the voltage of capacitor C4 increases, transistor T3 turns on. After T3 turns on, PMOS transistor Q1 also turns on. This structure ensures that the current supplied to the load gradually increases during power-up, preventing current surges that could impact the load. The load of a smart water meter includes the control chip, various sensors, and electrically controlled valves. Furthermore, the conduction of PMOS transistor Q1 ensures that the power supply circuit remains active, thus maintaining power supply stability.

[0035] In this embodiment, the detection circuit includes an antenna ANT, a low-pass filter circuit, a diode D2, and a comparator circuit;

[0036] The output terminal of the antenna ANT is connected to the input terminal of the low-pass filter circuit. The output terminal of the low-pass filter circuit is connected to the positive terminal of the diode D2. The negative terminal of the diode D2 is grounded through the capacitor C2. The negative terminal of the diode D2 is connected to the input terminal of the comparator circuit. The output terminal of the comparator circuit serves as the output terminal of the detection circuit.

[0037] Specifically, the low-pass filter circuit includes capacitor C1, capacitor C5, and inductor L1;

[0038] One end of capacitor C1 is connected to the output terminal of antenna ANT, and the other end of capacitor C1 is grounded. The common connection point between capacitor C1 and antenna ANT is connected to one end of inductor L1, and the other end of inductor L1 is grounded through capacitor C5. The common connection point between inductor L1 and capacitor C5 serves as the output terminal of the low-pass filter circuit. The low-pass filter is a π structure, which has a better filtering effect.

[0039] The comparison circuit includes comparator U1, resistor R1, resistor R2, resistor R3, and resistor R4;

[0040] The non-inverting input of comparator U1 is connected to one end of resistor R1, and the other end of resistor R1 serves as the input of the comparator circuit. One end of resistor R3 is connected to the output of the power supply control circuit, and the other end of resistor R3 is grounded through resistor R2. The common connection point between resistors R2 and R3 is connected to the inverting input of comparator U1. The output of comparator U1 is connected to one end of resistor R4, and the other end of resistor R4 serves as the output of the comparator circuit.

[0041] The comparison circuit also includes a capacitor C3, one end of which is connected to a resistor R4 as one end of the output terminal of the comparison circuit, and the other end of the capacitor C3 is grounded.

[0042] The detection control circuit includes transistor T1, transistor T2, and resistor R6;

[0043] The emitter of transistor T1 is connected to the source of PMOS transistor Q1. The collector of transistor T1 serves as the control output of the detection and control circuit. The base of transistor T1 is connected to the source of PMOS transistor Q1. The collector of transistor T2 is connected to the base of transistor T1 through resistor R6. The emitter of transistor T2 is grounded. The base of transistor T2 serves as the input of the detection and control circuit.

[0044] In this design, transistor T1 is a P-type transistor. During high-frequency electromagnetic interference, the smart water meter's shielding shell provides good shielding against such interference, but its shielding effect is poor against high-power, low-frequency signals, as mentioned in the background section. Therefore, an antenna detects the high-power, low-frequency electromagnetic signal, and diode D2 rectifies it to form DC. The greater the power of the low-frequency electromagnetic signal, the greater the amplitude of the DC voltage rectified by diode D2.When a certain value is reached (this value is a set value determined by the smart water meter itself; for example, through testing, when the power of low-frequency electromagnetic interference reaches a certain value, the shielding effect of the smart water meter decreases significantly, and the voltage value corresponding to the power of low-frequency electromagnetic interference at this time is the set value), comparator U1 outputs a high level; otherwise, comparator U1 outputs a low level. When comparator U1 outputs a high level, transistor T2 conducts, which in turn triggers T1 to conduct. Finally, PMOS transistor Q1 enters the cutoff state, shutting off the power supply circuit of the smart water meter. Of course, it cannot be shut off immediately, so capacitor C3 is used to delay the shutdown. An optocoupler is also set in the detection circuit. Resistors R5 and R12 are connected as follows: one end of resistor R1 is connected to the detection terminal CON of the smart water meter controller; the other end of resistor R12 is connected to the collector of the phototransistor in the optocoupler OCR1, with the emitter of the phototransistor grounded; one end of resistor R5 is connected to the output of comparator U1, and the other end of resistor R5 is connected to the anode of the LED in the optocoupler OCR1, with the cathode of the LED grounded. When the comparator outputs a low level, the optocoupler OCR1 is cut off. At this time, the common connection point between resistor R12 and the detection terminal of the smart water meter controller is set to a high level, indicating normal operation, and comparator U1 outputs a low level. At this time, optocoupler OCR1 conducts, and the common connection point between resistor R12 and the detection terminal of the smart water meter controller is set to a low level. The controller immediately generates an early warning signal indicating illegal interference. This early warning signal can be issued through a buzzer connected to the controller on-site (generally, the smart water meter itself has this alarm). On the other hand, it immediately uploads the signal to the server (although there is interference, the controller will still perform the upload action). Simultaneously, the controller stores the alarm information locally (for backup verification during upload) and controls the smart water meter's electrical valve (or solenoid valve) to shut off. These actions generated by the controller take priority over the conduction of transistor T2. The switching on is achieved by setting capacitor C3. When transistor T2 is turned on, there is no reverse conduction voltage drop between the gate and source of PMOS transistor Q1, thus turning off PMOS transistor Q1. This disconnects the various electrical components of the smart water meter, preventing damage from low-frequency electromagnetic interference. Although the smart water meter is in a power-off and water-off state at this time, the communication between the smart water meter's controller and the server (usually located at the water company) is also disconnected. When the server detects the disconnection, it will generate corresponding alarm information for troubleshooting. If a low-frequency interference alarm is transmitted to the server, the server will also generate a corresponding alarm, enabling timely troubleshooting.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A smart water meter anti-low-frequency interference power-off control device, characterized in that: Includes power supply control circuit, detection circuit, and detection control circuit; The power supply control circuit has its input terminal connected to the power supply of the smart water meter, and its output terminal supplying power to the load of the smart water meter. The detection circuit is used to detect low-frequency interference in the environment where the smart water meter is located and output a control signal under low-frequency interference. The detection control circuit has its input terminal connected to the output terminal of the detection circuit and its output terminal connected to the control terminal of the power supply control circuit. It is used to output a high level to the control terminal of the power supply control circuit when the detection circuit outputs a control signal and to turn off the power supply circuit of the power supply control circuit through the high level.

2. The intelligent water meter anti-low frequency interference power-off control device according to claim 1, characterized in that: The power supply control circuit includes a PMOS transistor Q1, resistors R7, R8, R9, R10, and R11, a diode D1, a transistor T3, and a self-resetting manual switch SW1. The source of PMOS transistor Q1 is connected to the power supply of the smart water meter as the input terminal of the power supply control circuit. The drain of PMOS transistor is connected to the positive terminal of diode D1. The negative terminal of diode D1 is used as the output terminal of the power supply control circuit to supply power to the load RL. One end of resistor R7 is connected to the source of PMOS transistor Q1, and the other end of resistor R7 is connected to the gate of PMOS transistor Q1. The gate of PMOS transistor Q1 is connected to the collector of transistor T3 through resistor R9. The emitter of transistor T3 is grounded. The drain of PMOS transistor Q1 is grounded through resistors R10 and R11 connected in series. The common connection point between resistors R10 and R11 is connected to the base of transistor T3. The drain of PMOS transistor Q1 is grounded through capacitor C4. One end of the self-reset manual switch SW1 is connected to the source of PMOS transistor Q1, and the other end of the self-reset manual switch is connected to the common ground between the drain of PMOS transistor Q1 and capacitor C4 through resistor R8. The gate of PMOS transistor Q1 serves as the control terminal of the power supply control circuit.

3. The intelligent water meter anti-low frequency interference power-off control device according to claim 2, characterized in that: The detection circuit includes an antenna ANT, a low-pass filter circuit, a diode D2, and a comparator circuit; The output terminal of the antenna ANT is connected to the input terminal of the low-pass filter circuit. The output terminal of the low-pass filter circuit is connected to the positive terminal of the diode D2. The negative terminal of the diode D2 is grounded through the capacitor C2. The negative terminal of the diode D2 is connected to the input terminal of the comparator circuit. The output terminal of the comparator circuit serves as the output terminal of the detection circuit.

4. The intelligent water meter anti-low frequency interference power-off control device according to claim 3, characterized in that: The low-pass filter circuit includes capacitor C1, capacitor C5, and inductor L1; One end of capacitor C1 is connected to the output terminal of antenna ANT, and the other end of capacitor C1 is grounded. The common connection point between capacitor C1 and antenna ANT is connected to one end of inductor L1, and the other end of inductor L1 is grounded through capacitor C5. The common connection point between inductor L1 and capacitor C5 serves as the output terminal of the low-pass filter circuit.

5. The intelligent water meter anti-low frequency interference power-off control device according to claim 3, characterized in that: The comparison circuit includes comparator U1, resistor R1, resistor R2, resistor R3, and resistor R4; The non-inverting input of comparator U1 is connected to one end of resistor R1, and the other end of resistor R1 serves as the input of the comparator circuit. One end of resistor R3 is connected to the output of the power supply control circuit, and the other end of resistor R3 is grounded through resistor R2. The common connection point between resistors R2 and R3 is connected to the inverting input of comparator U1. The output of comparator U1 is connected to one end of resistor R4, and the other end of resistor R4 serves as the output of the comparator circuit.

6. The intelligent water meter anti-low frequency interference power-off control device according to claim 5, characterized in that: The comparison circuit also includes a capacitor C3, one end of which is connected to a resistor R4 as one end of the output terminal of the comparison circuit, and the other end of the capacitor C3 is grounded.

7. The intelligent water meter anti-low frequency interference power-off control device according to claim 2, characterized in that: The detection control circuit includes transistor T1, transistor T2, and resistor R6; The emitter of transistor T1 is connected to the source of PMOS transistor Q1. The collector of transistor T1 serves as the control output of the detection and control circuit. The base of transistor T1 is connected to the source of PMOS transistor Q1. The collector of transistor T2 is connected to the base of transistor T1 through resistor R6. The emitter of transistor T2 is grounded. The base of transistor T2 serves as the input of the detection and control circuit. Among them, transistor T1 is a P-type transistor.

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