CN219086835U

CN219086835U - Power supply circuit and flowmeter

Info

Publication number: CN219086835U
Application number: CN202223211920.7U
Authority: CN
Inventors: 顾岱鸿; 刘广峰; 薛启启
Original assignee: Beijing Polydoctor Petroleum Technology Co ltd; China University of Petroleum Beijing
Current assignee: Beijing Polydoctor Petroleum Technology Co ltd; China University of Petroleum Beijing
Priority date: 2022-11-29
Filing date: 2022-11-29
Publication date: 2023-05-26
Anticipated expiration: 2032-11-29

Abstract

The utility model provides a power supply circuit and a flowmeter, and relates to the technical field of instruments and meters, wherein the power supply circuit comprises: the battery power supply module comprises a battery power supply and a balance circuit, and the battery power supply is connected with the balance circuit; the battery power supply comprises at least two batteries; the balance circuit is used for preventing the batteries from being mutually charged; the battery power supply module is used for providing a battery power supply mode for the flowmeter; the external power supply module comprises an external power interface, and the external power interface is used for connecting an external power supply; the external power supply module is used for providing an external power supply mode for the flowmeter; the power supply mode switching module is used for connecting the battery power supply module with the external power supply module and comprises a control module; the control module is used for switching the battery power supply mode to the external power supply mode when the connection of the external power supply is detected. By the mode, the flow meter is directly powered when the external power supply is switched, and the balance circuit is further arranged and can prevent the batteries from being mutually charged.

Description

Power supply circuit and flowmeter

Technical Field

The utility model relates to the technical field of instruments and meters, in particular to a power supply circuit and a flowmeter.

Background

In the natural gas collection and transmission process, metering mainly depends on a flowmeter. But at the initial stage of exploitation, on-site supporting facilities are crude, equipment cannot be normally powered, a conventional flowmeter cannot be normally used, and the problem can be solved by the low-power consumption flowmeter, so that on-site flow metering is realized.

The existing low-power consumption flowmeter mainly adopts a rechargeable lithium battery as a power source, and when external power supply is connected, the battery is supplied with power firstly, and then the battery supplies power for the whole system. However, the low-power consumption flowmeter is easy to overcharge due to no charge detection, and the battery is damaged, so that the whole equipment cannot be used normally.

Disclosure of Invention

The utility model provides a power supply circuit and a flowmeter, which are used for solving the problem that the internal battery is charged preferentially when the flowmeter is externally connected with a power supply in the prior art, and overcharge is easy to cause.

The present utility model provides a power supply circuit comprising: the battery power supply module comprises a battery power supply and a balance circuit, and the battery power supply is connected with the balance circuit; the battery power supply comprises at least two batteries; the balance circuit is used for preventing the batteries from being mutually charged; the battery power supply module is used for providing a battery power supply mode for the flowmeter; the external power supply module comprises an external power interface, and the external power interface is used for connecting an external power supply; the external power supply module is used for providing an external power supply mode for the flowmeter; the power supply mode switching module is used for connecting the battery power supply module with the external power supply module and comprises a control module; the control module is used for switching the battery power supply mode to the external power supply mode when the connection of the external power supply is detected.

According to the power supply circuit provided by the utility model, the power supply mode switching module further comprises a photoelectric isolation circuit and a triode circuit, wherein the photoelectric isolation circuit is respectively connected with an external power interface and a control module in the external power supply module, and the triode circuit is respectively connected with the control module and a node between a battery power supply and a balance circuit in the battery power supply module; the photoelectric isolation circuit is used for detecting whether an external power supply is connected with an external power supply interface or not; the triode circuit is used for disconnecting the power supply of the battery power supply module when the triode circuit is connected with an external power supply.

The power supply circuit provided by the utility model further comprises a step-up and step-down processing module, wherein the step-up and step-down processing module is respectively connected with the battery power supply module, the external power supply module and the power supply mode switching module; the buck-boost processing module is used for converting the first voltage provided by the battery power supply module into the second voltage when in the battery power supply mode, and converting the third voltage into the second voltage when in the external power supply mode.

According to the power supply circuit provided by the utility model, the first voltage is 2.8V-3.6V; the second voltage is 3.3V; the third voltage is 24V.

According to the power supply circuit provided by the utility model, the batteries are lithium thionyl chloride batteries, and a parallel connection mode is adopted between the batteries.

The utility model also provides a flowmeter, which comprises a control system, a man-machine interaction system, a communication system, a data acquisition system and a power supply circuit of the flowmeter; the power supply circuit, the man-machine interaction system, the communication system and the data acquisition system are respectively connected with the control system.

According to the flowmeter provided by the utility model, in an external power supply mode, the control system adjusts the working frequency of the flowmeter to be a first working frequency; in the battery power supply mode, the control system adjusts the operating frequency of the flowmeter to a second operating frequency; wherein the first operating frequency is higher than the second operating frequency.

According to the flowmeter provided by the utility model, the first working frequency is 72Mhz, and the second working frequency is 24Mhz.

The flowmeter provided by the utility model further comprises a key wake-up circuit; the man-machine interaction system comprises a display module; in an external power supply mode, the key wake-up circuit outputs a high-level signal, and the control system supplies power to the man-machine interaction system and the communication system in response to the high-level signal of the key wake-up circuit; in the battery power supply mode, the key wake-up circuit outputs a low-level signal, and the control system stops supplying power to the display module and the communication system in response to the low-level signal of the key wake-up circuit.

According to the flowmeter provided by the utility model, the flowmeter further comprises two zero calibration keys, and when the two zero calibration keys are triggered simultaneously, the flowmeter performs zero calibration.

The utility model provides a power supply circuit and a flowmeter, wherein the power supply circuit comprises: the battery power supply module comprises a battery power supply and a balance circuit, and the battery power supply is connected with the balance circuit; the battery power supply comprises at least two batteries; the balance circuit is used for preventing the batteries from being mutually charged; the battery power supply module is used for providing a battery power supply mode for the flowmeter; the external power supply module comprises an external power interface, and the external power interface is used for connecting an external power supply; the external power supply module is used for providing an external power supply mode for the flowmeter; the power supply mode switching module is used for connecting the battery power supply module with the external power supply module and comprises a control module; the control module is used for switching the battery power supply mode to the external power supply mode when the connection of the external power supply is detected. By the mode, the flow meter is directly powered when the external power supply is switched, and the balance circuit is further arranged and can prevent the batteries from being mutually charged.

Drawings

In order to more clearly illustrate the utility model or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the utility model, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of an embodiment of a power supply circuit of the present utility model;

FIG. 2 is a schematic diagram of another embodiment of a power supply circuit of the present utility model;

FIG. 3 is a schematic circuit diagram of an embodiment of a photo-isolation circuit according to the present utility model;

FIG. 4 is a schematic circuit diagram of an embodiment of a battery power module and a power mode switching module according to the present utility model;

FIG. 5 is a schematic circuit diagram of an embodiment of an external power module according to the present utility model;

FIG. 6 is a schematic diagram of an embodiment of a flowmeter of the present utility model;

FIG. 7 is a schematic diagram illustrating operation of an embodiment of a key wake-up circuit according to the present utility model;

fig. 8 is a schematic circuit diagram of a key wake-up circuit according to an embodiment of the utility model.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the present utility model more apparent, the technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present utility model, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Referring to fig. 1, fig. 1 is a schematic diagram illustrating a power supply circuit according to an embodiment of the utility model. In this embodiment, the power supply circuit may include: a battery power supply module 110, an external power supply module 120, and a power supply mode switching module 130.

The battery power supply module 110 comprises a battery power supply and a balance circuit, wherein the battery power supply is connected with the balance circuit; the battery power supply comprises at least two batteries; the balance circuit is used for preventing the batteries from being mutually charged; the battery powered module 110 is used to provide a battery powered mode for the flow meter.

Optionally, the batteries are lithium thionyl chloride batteries, and a parallel connection mode is adopted between the batteries. Wherein the lithium thionyl chloride battery is a disposable battery and cannot be charged.

The external power supply module 120 includes an external power interface for connecting an external power source; the external power module 120 is used to provide an external power mode for the flow meter.

The power supply mode switching module 130 is used for connecting the battery power supply module and the external power supply module, and comprises a control module; the control module is used for switching the battery power supply mode to the external power supply mode when the connection of the external power supply is detected. Alternatively, the control module may be an ARM controller.

In some embodiments, the power supply mode switching module further includes a photo-isolation circuit and a triode circuit, referring to fig. 2, fig. 2 is a schematic diagram of a power supply circuit according to another embodiment of the present utility model.

The battery powered module 210 includes a battery power supply and balancing circuitry. The power mode switching module 230 includes a control module, a photo-isolation circuit, and a triode circuit. The external power module 220 includes an external power interface.

The photoelectric isolation circuit is respectively connected with an external power interface and a control module in the external power supply module, and the triode circuit is respectively connected with the control module and a node between a battery power supply and the balance circuit in the battery power supply module 210; the photoelectric isolation circuit is used for detecting whether an external power supply is connected with an external power supply interface or not; the triode circuit is used for disconnecting the power supply of the battery power supply module 210 when the external power supply is connected.

Referring to fig. 3, fig. 3 is a schematic circuit structure of an embodiment of the optoelectronic isolation circuit of the present utility model. In this embodiment, the optoelectronic isolation circuit includes a first resistor R1, a first capacitor C1, a light emitting diode LED1, and a first chip U1.

The first chip U1 includes four pins. The first end of the first resistor R1 is connected with the working voltage positive pole VIN+, the second end of the first resistor R1 is connected with the input end of the light emitting diode LED1, and the output end of the light emitting diode LED1 is connected with the first pin of the first chip U1.

The second pin of the first chip U1 is connected with the working voltage negative electrode VIN-, and the first capacitor C1 is connected between the first end of the first resistor R1 and the second pin of the first chip U1. The third pin of the first chip U1 is connected to the node 3V3, and the fourth pin of the first chip U1 is connected to another place, irrespective of the present solution, which is not described here.

The chip type of the first chip U1 may be IS281GR.

In some embodiments, the power supply circuit may further include a buck-boost processing module. With continued reference to fig. 2, the buck-boost processing module 240 is respectively connected to the battery power module 210, the external power module 220, and the power mode switching module 230; the buck-boost processing module 240 is configured to convert a first voltage provided by the battery power module into a second voltage in the battery power mode and convert a third voltage into the second voltage in the external power mode.

Optionally, the first voltage is 2.8V to 3.6V; the second voltage is 3.3V; the third voltage is 24V.

Alternatively, the buck-boost processing module 240 may include a DCDC buck circuit and a DCDC buck-boost circuit. The DCDC step-down circuit is respectively connected with an external power interface, and the DCDC step-up and step-down circuit is respectively connected with the balance circuit and the DCDC step-up and step-down circuit. The step-up and step-down processing module stabilizes the first voltage or the third voltage at the second voltage, so that the normal operation of the back-end circuit is realized.

For example, the DCDC buck-boost circuit may stabilize a battery voltage of 2.6V to 4.2V at 3.3V. The DCDC voltage reduction circuit can stabilize the 24V battery voltage at 3.3V. The buck-boost processing module can provide an operating voltage of 3.3V for the back-end circuit.

Referring to fig. 4-5, fig. 4 is a schematic circuit diagram of an embodiment of a battery power module and a power mode switching module according to the present utility model. Fig. 5 is a schematic circuit diagram of an embodiment of an external power module according to the present utility model.

In this embodiment, the battery power supply module and the power supply mode switching module may include a battery, a first diode D1, a second resistor R2, a first switch SW1, a first fuse F1, a second capacitor C2, a third capacitor C3, a second chip U2, a third resistor R3, a fourth capacitor C4, a fourth resistor R4, a first transistor Q1, and a third chip U3.

The second chip U2 and the third chip U3 each include 6 pins, wherein the sixth pins (N/C) of the second chip U2 and the third chip U3 are all connected in a blank.

The battery includes two pins, which serve as a battery positive electrode B + and a battery negative electrode B-, respectively. The input end of the first diode D1 is connected with the battery anode B+, and the output end of the first diode D1 is connected with the first end of the second resistor R2. Battery negative electrode B-ground GND.

The first diode D1 is a threshold diode, which is equivalent to the function of a balancing circuit, so that the voltages output by the batteries are balanced.

The first switch SW1 includes three pins. The second end of the first switch SW1 is connected to the second end of the second resistor R2, the third end of the first switch SW1 is connected to the first end of the first fuse F1, and the first end of the first switch SW1 is connected in an idle state. The second end of the first switch SW1 is a fixed end, and the first end and the third end of the first switch SW1 are movable ends.

The second end of the first fuse F1 is connected to the fourth pin (IN) of the second chip U2. The third resistor R3 is connected between the fourth pin (IN) and the third pin (ON/OFF) of the second chip U2.

The second capacitor C2 and the third capacitor C3 are connected in parallel, and the other end of the second capacitor C2 and the third capacitor C3 connected in parallel is grounded GND between one end and a node between the third resistor R3 and the second chip U2 and between the second end of the first fuse F1.

The fifth pin (GND) and the second pin (GND) of the second chip U2 are grounded GND,

the first pin (OUT) of the second chip U2 is connected to the node 3V 3.

The first end of the fourth capacitor C4 is connected to the first pin (OUT) of the second chip U2, and the second end of the fourth capacitor C4 is grounded GND.

The input end of the first triode Q1 is connected with the first end of the fourth resistor R4, the first end of the first triode Q1 is connected with a node between the third resistor R3 and a third pin (ON/OFF) of the second chip U2, and the second end of the first triode Q1 is grounded GND.

The fifth pin (GND) and the second pin (GND) of the third chip U3 are grounded GND, the fourth pin (IN) of the third chip U3 is connected with the second end of the fourth resistor R4, and the fourth pin (IN) of the third chip U3 is connected with the third pin (ON/OFF) of the third chip U3.

The third pin (ON/OFF) of the third chip U3 is connected to the node 1V1; the first pin (OUT) of the third chip U3 is connected to other circuits, irrespective of the present solution, and is omitted here.

As shown in fig. 5, the external power supply includes a first pin and a second pin, the second pin is used as a positive pole vin+ of the operating power supply, and the first pin is used as a negative pole VIN-of the operating power supply. The first end of the second fuse F2 is connected to the positive electrode vin+, and the second end of the second fuse F2 is connected to the input end of the second diode D2.

The transformer T1 comprises four pins, a first pin of the transformer T1 is connected with the output end of the second diode D2, and a second pin of the transformer T1 is connected with the negative electrode VIN-. The first end of the varistor RV1 is connected to a node between the second end of the second fuse F2 and the input of the second diode D2, and the second end of the varistor RV1 is connected to a node between the second pin of the transformer T1 and the negative pole VIN-.

The third diode D3, the fifth capacitor C5 and the sixth capacitor are connected in parallel, one end of the third diode D is connected to the fourth pin of the transformer T1, and the other end of the third diode D is connected to the third pin of the transformer T1. The input end of the third diode D3 is connected to the third pin of the transformer T1, and the output end of the third diode D3 is connected to the fourth pin of the transformer T1.

The fourth chip U4 includes five pins, wherein the fourth does not participate in the connection of the present solution. The first pin (GND) of the fourth chip U4 is connected to the third pin of the transformer T1. The second pin (VIN) of the fourth chip U4 is connected to the fourth pin of the transformer T1.

The first end of the seventh capacitor C7 is connected to the second pin (VIN) of the fourth chip U4, and the second end of the seventh capacitor C7 is connected to the third pin (+vo) of the fourth chip U4. The first end of the eighth capacitor C8 is connected to the first pin (GND) of the fourth chip U4, and the second end of the eighth capacitor C8 is connected to the fifth pin (0V) of the fourth chip U4. The fifth pin (0V) of the fourth chip U4 is grounded GND.

The first end of the first inductor L1 is connected to the third pin (+vo) of the fourth chip U4, and the second end of the first inductor L1 is connected to a node between the fifth pin (SD), the seventh pin (IN), and the eighth pin (IN/2) of the fifth chip U5. The fifth pin (SD), the seventh pin (IN) and the eighth pin (IN/2) of the fifth chip U5 are connected.

The ninth capacitor C9, the tenth capacitor C10 and the eleventh capacitor C11 are connected in parallel, one end of which is connected to a node between the third pin (+ VO) of the fourth chip U4 and the first end of the first inductor L1, and the other end of which is grounded GND.

The twelfth capacitor C12 and the thirteenth capacitor C13 are connected in parallel, one end of which is connected to a node between the pin of the fifth chip U5 and the second end of the first inductor L1, and the other end of which is grounded GND.

The sixth pin (ERR) of the fifth chip U5 is connected to the ground GND, and the fourth pin (GND) of the fifth chip U5 is connected to the ground GND. The third pin (NR) of the fifth chip U5 is connected to the first end of the fifteenth capacitor C15, and the second pin (OUT) of the fifth chip U5, the first pin (OUT/2) of the fifth chip U5, the second end of the fifteenth capacitor C15, and the first end of the fourteenth capacitor C14 are connected together to connect the node 1V1. The second terminal of the fourteenth capacitor C14 is grounded.

The second chip U2 and the third chip U3 have the same model and are SIP32431DR3-T1GE3. The fourth chip U4 is model URB2405YMD-6WR3. The signal of the fifth chip U5 is ADP3303ARZ-3.3.

In summary, the present utility model provides a power supply circuit, which can achieve the following technical effects:

1. cell output balance: when no external power is supplied, a plurality of batteries are used as a working source of the system, a balance circuit is designed at the output end of each battery, the balance circuit can ensure the balance of the voltage output of the batteries, the phenomenon that the system cannot work due to the mutual charging of the batteries is prevented, and a DCDC voltage stabilizing circuit is designed at the rear end of each diode to output stable voltage.

2. External power supply and battery power supply automatic switch-over: when an external power supply is input, a triode and a power switch chip are adopted to switch the power supply of the system to the external power supply.

The present utility model also provides a flowmeter, referring to fig. 6, fig. 6 is a schematic structural diagram of an embodiment of the flowmeter according to the present utility model, where in the embodiment, the flowmeter may include a control system 610, a man-machine interaction system 620, a communication system 630, a data acquisition system 640, and a power supply circuit 650 of the flowmeter.

The power supply circuit 650, the man-machine interaction system 620, the communication system 630 and the data acquisition system 640 are respectively connected to the control system 610.

The man-machine interaction system 620 is used for inputting user instructions and feeding back processing results to the user. The communication system 630 is used to implement wireless communication, and may remotely receive a user instruction or remotely feed back a processing result. The data acquisition system 640 is used to enable measurement of flow.

In some embodiments, in the external power mode, the control system adjusts the operating frequency of the flow meter to a first operating frequency; in the battery power supply mode, the control system adjusts the operating frequency of the flowmeter to a second operating frequency; wherein the first operating frequency is higher than the second operating frequency.

Alternatively, the first operating frequency is 72Mhz and the second operating frequency is 24Mhz.

In some embodiments, the flow meter may further comprise a key wake-up circuit; the man-machine interaction system comprises a display module; in an external power supply mode, the key wake-up circuit outputs a high-level signal, and the control system supplies power to the man-machine interaction system and the communication system in response to the high-level signal of the key wake-up circuit; in the battery power supply mode, the key wake-up circuit outputs a low-level signal, and the control system stops supplying power to the display module and the communication system in response to the low-level signal of the key wake-up circuit.

Referring to fig. 7-8, fig. 7 is a schematic diagram illustrating an operation of an embodiment of the key wake-up circuit of the present utility model, and fig. 8 is a schematic diagram illustrating a circuit structure of an embodiment of the key wake-up circuit of the present utility model.

As shown in fig. 7, the control system may be an ARM module, the control module in the power supply system may be an ARM controller, and the ARM controller may be integrated in the ARM module. The ARM module can also comprise a FLASH controller.

The key wake-up circuit sends a low-level signal or a low-level signal to the ARM module, and the ARM module responds to the level signal to control the power switch so as to control the power supply of the man-machine interaction system and the communication system.

As shown in fig. 8, the key wake-up circuit includes a push button switch S1, a second triode Q2, a sixteenth capacitor C16, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7.

The first end of the seventh resistor R7 is connected to the node 3V3, the second end of the seventh resistor R7 is connected to the first end of the push button switch S1, and the second end of the push button switch S1 is grounded to GND. The first end of the fifth resistor is connected with the first end of the second triode Q2, the second end of the second triode Q3 is connected with the node 3V3, the input end of the second triode Q3 is connected with the first end of the sixth resistor R6, and the second end of the sixth resistor R6 is connected with a node between the second end of the seventh resistor R7 and the first end of the button switch S1.

The first terminal of the sixteenth capacitor C16 is connected to a node between the second terminal of the sixth resistor R6, the second terminal of the seventh resistor R7 and the first terminal of the push button switch S1. The second end of the fifth resistor R5 and the second end of the sixteenth capacitor C16 are grounded.

The nodes 3V3 and 1V1 are different circuits connected to the same node.

In some embodiments, the flow meter further comprises two zero calibration keys, the flow meter performing zero calibration when both zero calibration keys are activated simultaneously. When the flow is empty, the zero calibration of the equipment is carried out through the two keys at the same time, so that the device is stable and reliable, and misoperation of the key jitter controller is prevented.

In summary, the utility model also provides a flowmeter with low power consumption, which is mainly characterized in the following aspects:

1. the key wake-up circuit controls the power switch to enable the man-machine interaction system and the communication system to work normally only when the control system receives a high-level signal of the key wake-up circuit, and the man-machine interaction system and the communication system can be suspended to work when the control system is not needed, so that the working power consumption is reduced.

2. The working frequency of the battery in the power supply mode is lower than that of the battery in the external power supply mode, so that the power consumption of the system can be reduced, and the service time of the internal battery can be prolonged.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present utility model, and are not limiting; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present utility model.

Claims

1. A power supply circuit, comprising:

the battery power supply module comprises a battery power supply and a balance circuit, wherein the battery power supply is connected with the balance circuit; the battery power supply comprises at least two batteries; the balance circuit is used for preventing the batteries from being mutually charged; the battery power supply module is used for providing a battery power supply mode for the flowmeter;

the external power supply module comprises an external power interface, and the external power interface is used for connecting an external power supply; the external power supply module is used for providing an external power supply mode for the flowmeter;

the power supply mode switching module is used for connecting the battery power supply module and the external power supply module and comprises a control module; the control module is used for switching the battery power supply mode to the external power supply mode when the connection of the external power supply is detected.

2. The power supply circuit of claim 1, wherein the power supply mode switching module further comprises a photo-isolation circuit and a triode circuit, the photo-isolation circuit being respectively connected to the external power supply interface in the external power supply module and the control module, the triode circuit being respectively connected to nodes between the battery power supply and the balancing circuit in the control module and the battery power supply module;

the photoelectric isolation circuit is used for detecting whether the external power supply is connected with the external power supply interface or not; the triode circuit is used for disconnecting the power supply of the battery power supply module when the external power supply is connected.

3. The power supply circuit of claim 1, further comprising a buck-boost processing module connected to the battery power supply module, the external power supply module, and the power supply mode switching module, respectively;

the buck-boost processing module is used for converting a first voltage provided by the battery power supply module into a second voltage when in the battery power supply mode, and converting a third voltage into the second voltage when in the external power supply mode.

4. A power supply circuit according to claim 3, wherein the first voltage is 2.8V to 3.6V; the second voltage is 3.3V; the third voltage is 24V.

5. The power supply circuit of claim 1, wherein the batteries are lithium thionyl chloride batteries, and wherein the batteries are connected in parallel.

6. A flowmeter comprising a control system, a human-machine interaction system, a communication system, a data acquisition system, and the power supply circuit of the flowmeter of any of claims 1-5;

the power supply circuit, the man-machine interaction system, the communication system and the data acquisition system are respectively connected with the control system.

7. The flowmeter of claim 6, wherein,

the control system adjusts the operating frequency of the flowmeter to a first operating frequency when in the external power supply mode; the control system adjusts the operating frequency of the flow meter to a second operating frequency when in the battery-powered mode; wherein the first operating frequency is higher than the second operating frequency.

8. The flowmeter of claim 7, wherein,

the first operating frequency is 72Mhz and the second operating frequency is 24Mhz.

9. The flowmeter of claim 6, further comprising a key wake-up circuit; the man-machine interaction system comprises a display module;

when in the external power supply mode, the key wake-up circuit outputs a high-level signal, and the control system supplies power to the man-machine interaction system and the communication system in response to the high-level signal of the key wake-up circuit;

and in the battery power supply mode, the key wake-up circuit outputs a low-level signal, and the control system stops supplying power to the display module and the communication system in response to the low-level signal of the key wake-up circuit.

10. The flowmeter of claim 7, further comprising two zero calibration keys, wherein the flowmeter performs zero calibration when the two zero calibration keys are activated simultaneously.