Ultrasonic gas metering circuit

Abstract

The utility model relates to an ultrasonic wave gas meter measurement circuit. The boost power conversion circuit is used for converting the input low voltage power supply into high voltage output, the voltage output control circuit is connected with the boost power conversion circuit, the high voltage output is controlled by external signal, and it is decided whether to supply power to the subsequent circuit, the transducer working circuit selects the emission and reception transducer through analog switch, is used for emitting and receiving ultrasonic wave signal, the multi-gear adjustable amplification signal circuit includes operational amplifier and four channel analog switch, and the received ultrasonic wave signal is switched through four channel analog switch feedback resistance and realizes gain adjustable. The boost power conversion circuit of the utility model realizes the step-up of output voltage, controls output voltage through the synergistic effect of field effect tube and control signal, realizes the function of overcurrent protection, and the multi-gear adjustable amplification signal circuit selects suitable amplification multiple, ensures the signal intensity required to be obtained, and improves the measurement accuracy and system stability.

Description

Technical Field

[0001] This utility model relates to an ultrasonic gas metering circuit. Background Technology

[0002] In ultrasonic gas metering instruments, the metering circuit is the core component, playing a decisive role in the accurate transmission, reception, and processing of ultrasonic signals, as well as the accurate calculation of flow rate.

[0003] With the upgrading of smart gas metering technology, ultrasonic metering has been gradually applied to residential and commercial gas metering scenarios due to its advantages such as high sensitivity and accurate measurement. However, existing solutions still face many technical bottlenecks in practical applications, directly affecting metering accuracy and system stability: various interference factors in the external environment can easily interfere with the propagation and reception of ultrasonic waves, significantly affecting metering accuracy; when the gas flow rate is under different operating conditions, the signal quality received by the ultrasonic transducer varies, which will directly interfere with the accuracy of gas metering results, especially in various gas environments, where the signal-to-noise ratio drops sharply compared to the air environment; and when the system experiences abnormal load, overcurrent, short circuit, or enters a dormant state, it will also pose a severe challenge to the stable operation of the ultrasonic metering circuit. Utility Model Content

[0004] In view of the problems existing in the prior art, the purpose of this utility model is to provide a technical solution for an ultrasonic gas meter metering circuit.

[0005] The ultrasonic gas meter metering circuit is characterized by comprising: A boost power converter circuit is used to convert a low-voltage input power supply into a high-voltage output. The voltage output control circuit is connected to the boost power conversion circuit. The high voltage output is controlled by an external signal to determine whether to supply power to subsequent circuits. The transducer operating circuit includes two transducers and an analog switch. The analog switch is used to select the transmitting and receiving transducers for transmitting and receiving ultrasonic signals. The multi-level adjustable signal amplification circuit includes an operational amplifier and a four-channel analog switch. The received ultrasonic signal is switched by the four-channel analog switch to achieve adjustable gain through switching the feedback resistor. The output of the boost power conversion circuit is connected to the transducer working circuit via the voltage output control circuit, and the output signal of the transducer working circuit is sent to the multi-level adjustable amplification signal circuit.

[0006] The ultrasonic gas meter metering circuit is characterized in that the boost power conversion circuit uses a boost chip U5, model TPS61096A. The boost chip U5 achieves voltage boosting through inductor L5, and achieves output voltage stabilization and filtering through feedback resistors R13 and R20, and capacitors C24 and C31.

[0007] The ultrasonic gas meter metering circuit is characterized in that the voltage output control circuit includes a field-effect transistor Q6 and a field-effect transistor Q7. The conduction and cutoff of the field-effect transistor Q7 are controlled by the control signal Tx5vEn, thereby controlling the conduction state of the field-effect transistor Q6 and realizing the switching control of the VCC-TX voltage output.

[0008] The ultrasonic gas meter metering circuit is characterized in that the analog switch U7 of the transducer working circuit is model TS12A44515, and one transducer is selected as the transmitter and the other as the receiver by control signal Sel1 and control signal Sel2.

[0009] The ultrasonic gas meter metering circuit is characterized in that the multi-level adjustable amplification signal circuit includes: The four-channel analog switch U4, model number TMUX1204; Operational amplifier U10, model OPA838; Multiple feedback resistors are connected to different channels of the four-channel analog switch U4; Among them, the four-channel analog switch U4 selects different feedback resistors connected to the inverting input terminal of the operational amplifier U10 through the control signal to realize the switching of gain levels.

[0010] The ultrasonic gas meter metering circuit is characterized in that the operational amplifier U10 constitutes a non-inverting amplifier circuit, its positive input terminal receives the input signal through capacitor C43, and its inverting input terminal forms negative feedback with the output terminal through a selected feedback resistor.

[0011] The ultrasonic gas meter metering circuit is characterized in that the feedback resistors are feedback resistor R15, feedback resistor R23, feedback resistor R24 ​​and feedback resistor R27.

[0012] The ultrasonic gas meter metering circuit is characterized in that the multi-level adjustable amplification signal circuit further includes an enable control signal RxEn, which is used to control the shutdown and activation of the operational amplifier U10.

[0013] The ultrasonic gas meter metering circuit is characterized in that the boost power conversion circuit boosts the 3.0V input voltage to 12V output.

[0014] Advantages of this utility model: 1. The multi-level adjustable signal amplification circuit selects four different channels and connects the corresponding feedback resistors (R15, R23, R24, R27) to the feedback loop of the operational amplifier. Different resistor values ​​correspond to different gain levels, thereby achieving precise adjustment of the amplification factor. This allows the circuit to flexibly switch the gain according to the actual amplitude of the transducer output signal, avoiding the signal weakness or saturation problems that occur in fixed-gain circuits in wide-range measurement. It ensures optimal signal processing under various flow conditions, improving the adaptability and overall accuracy of the metering system.

[0015] 2. Since signal amplitude is proportional to supply voltage, the boost power conversion circuit significantly enhances the relative amplitude of the useful signal strength with respect to noise after increasing the supply voltage to 12V. This effectively improves the signal-to-noise ratio, signal purity, and anti-interference performance. This design helps suppress the phenomenon of weak signals being overwhelmed by noise, reduces the risk of missed or incorrect measurements during low-flow metering, and significantly improves the stability and accuracy of the entire metering system. It is particularly suitable for gas meter applications in low-power designs, long-distance signal transmission, or complex electromagnetic environments.

[0016] 3. The voltage output control circuit can quickly cut off the high voltage in case of abnormal load, overcurrent, short circuit, or system hibernation, effectively avoiding unnecessary power consumption and heat generation, and protecting subsequent circuits in fault conditions; it automatically turns on during normal operation to ensure that the metering and transmitting modules receive sufficient driving force. This enables on-demand power supply for both high and low voltage loads, significantly reducing overall power consumption while ensuring full functionality, greatly extending charging cycles or battery life, and further improving the reliability and intrinsic safety performance of the smart gas meter. Attached Figure Description

[0017] Figure 1 This is a block diagram of the modules of this utility model; Figure 2 This utility model relates to a boost power conversion circuit and a voltage output control circuit; Figure 3 This is the transducer working circuit of this utility model; Figure 4 This utility model relates to a multi-level adjustable signal amplification circuit. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings: An ultrasonic gas meter metering circuit includes: a boost power conversion circuit for converting an input low-voltage power supply into a high-voltage output; a voltage output control circuit connected to the boost power conversion circuit, wherein the high-voltage output is controlled by an external signal to determine whether to supply power to subsequent circuits; a transducer operating circuit including two transducers and an analog switch, wherein the analog switch selects the transmitting and receiving transducers for transmitting and receiving ultrasonic signals; and a multi-level adjustable amplification signal circuit including an operational amplifier and a four-channel analog switch, wherein the received ultrasonic signal achieves adjustable gain by switching the feedback resistor through the four-channel analog switch; the output of the boost power conversion circuit is connected to the transducer operating circuit via the voltage output control circuit, and the output signal of the transducer operating circuit is sent to the multi-level adjustable amplification signal circuit.

[0019] The boost power conversion circuit uses a boost chip U5, model TPS61096A. The boost chip U5 achieves voltage boosting through inductor L5, and achieves output voltage stabilization and filtering through feedback resistors R13 and R20, and capacitors C24 and C31. The boost power conversion circuit boosts the 3.0V input voltage to 12V output.

[0020] The voltage output control circuit includes a P-channel MOSFET Q6 and an N-channel MOSFET Q7. The N-channel MOSFET Q7 is turned on and off by the control signal Tx5vEn, which in turn controls the conduction state of the P-channel MOSFET Q6, thereby realizing the switching control of the VCC-TX voltage output.

[0021] The analog switch U7 in the transducer operating circuit, model TS12A44515, selects one transducer as the transmitter and the other as the receiver through control signals Sel1 and Sel2.

[0022] The multi-level adjustable amplification signal circuit includes: a four-channel analog switch U4, model TMUX1204; an operational amplifier U10, model OPA838; and multiple feedback resistors (feedback resistor R15, feedback resistor R23, feedback resistor R24, and feedback resistor R27), which are respectively connected to different channels of the four-channel analog switch U4. The four-channel analog switch U4 selects different feedback resistors connected to the inverting input of the operational amplifier U10 through a control signal to realize the switching of gain levels.

[0023] The multi-level adjustable amplification signal circuit also includes an enable control signal RxEn, used to control the turn-off and enable of operational amplifier U10. Operational amplifier U10 forms a non-inverting amplifier circuit, with its positive input terminal receiving the input signal through capacitor C43, and its inverting input terminal forming negative feedback with the output terminal through a selected feedback resistor. Example

[0024] Figure 2 The boost power conversion circuit, with boost chip U5 as its core, realizes the function of "input voltage boosting and subsequent voltage output control". In the specific implementation scheme, the boost chip model TPS61096A is used. The level conversion pins 1 and 2 of boost chip U5 are directly grounded. The power input pin 3 of boost chip U5 is connected to the input power supply EXT_VCC, and is also grounded through capacitors C22 and C26, and is also connected to the switching pin 4 of U5 through inductor L5. The inductor peak current limit selection pin 5 of U5 is directly grounded. The output voltage feedback pin 7 of U5 is connected to the output voltage detection pin 8 of chip U5 through resistor R13 and capacitor C24 in parallel; at the same time, the output voltage feedback pin 7 of U5 is connected to the PAD pin 13 of U5 through resistor R20 and grounded. The ground pin 10 of U5 is directly grounded.

[0025] U5 is a boost DC-DC converter that uses the property of an inductor to generate an induced voltage that prevents current changes, thus boosting the voltage. The input voltage EXT_VCC is filtered by capacitors C22 and C26 to remove power supply noise and provide a stable input voltage for the boost chip. The chip's EN pin 6 is connected to the control signal TxPwr. When TxPwr is low, the inductor is in an energy storage state, stopping the boost function; when TxPwr is high, inductor L5 discharges, and the boost function begins. Inductor L5 alternately stores energy and releases energy to the output during the on / off cycles of the internal transistors, achieving the boost. Resistors R13 and R20, after voltage division, are connected to the chip's FB pin 7, adjusting the internal switching logic through feedback to stabilize the output voltage within the required range. Capacitor C31 filters the boosted output voltage, significantly reducing ripple amplitude and improving voltage stability.

[0026] Output pin 9 of U5 is grounded through capacitor C31 and connected to the source (S) of MOSFET Q6. It is also connected to the gate (G) of MOSFET Q6 through resistor R10 and to the drain (D) of MOSFET Q7 through resistor R9. The drain (D) of MOSFET Q6 is connected to the voltage output node VCC-TX through resistor FB1. The gate of MOSFET Q7 is connected to the control signal Tx5vEn, and its gate is connected to the source (S) through resistor R7 and grounded. MOSFET Q6 is a P-channel MOSFET, and Q7 is an N-channel MOSFET.

[0027] The voltage output control circuit determines whether the boosted voltage is transmitted to the VCC-TX voltage output node. When subsequent circuits require voltage, the control signal Tx5vEn outputs a high level, and MOSFET Q7 is turned on. The drain of MOSFET Q7 is essentially grounded, pulling the gate voltage of MOSFET Q6 down to a low level. MOSFET Q6 then conducts because its gate voltage is lower than its source voltage. At this time, the boosted voltage is output from MOSFET Q6 through the current-limiting resistor FB1 to VCC-TX. FB1 is a current-limiting resistor to prevent overcurrent. When subsequent circuits do not require voltage, the control signal Tx5vEn outputs a low level: MOSFET Q7 is turned off. Therefore, the source (S) and gate (G) of MOSFET Q6 are both connected to a high level, MOSFET Q6 is turned off, and the voltage output node VCC-TX has no output.

[0028] Figure 3This is the transducer operating circuit, including a 4-channel analog switch U7, MOSFETs Q8 and Q9, transducer one J5, transducer two J6, filter capacitor C33, and pull-down resistor R49. The high voltage VCC-TX output from the voltage output control circuit is input to the drains of MOSFETs Q8 and Q9 via resistors R21 and R22, respectively. The external control signal RxSel1 is input to the gate of MOSFET Q8. The source of MOSFET Q8 is directly grounded. When the external control signal RxSel1 is high, the gate voltage of MOSFET Q8 is greater than the source voltage, MOSFET Q8 is turned on, and the drain of MOSFET Q8 is pulled to the source potential (USS_GND), and the control signal Sel1 outputs a low level. Conversely, when the external control signal RxSel1 is low, MOSFET Q8 is turned off, and the drain of MOSFET Q8 is pulled up to a high level by the resistor, and the control signal Sel1 outputs a high level. The operating principle of external control signals RxSel2 and Sel2 is the same as that of external control signals RxSel1 and Sel1. The high voltage VCC-TX is connected to pin 14 of the power input of the 4-channel analog switch U7. Pins 1 and 8 of the 4-channel analog switch U7 are simultaneously connected to transducer one J5, and pins 3 and 11 of the 4-channel analog switch U7 are simultaneously connected to transducer two J6. In this example, the analog switch U7 is a TS12A44515 four-channel analog switch. External control signals (RxSel1, RxSel2) are converted from high to low levels by MOSFETs Q8 and Q9 to obtain Sel1 and Sel2 that analog switch U7 can recognize. The high and low levels of Sel1 / Sel2 control the on / off switching of the internal switch of analog switch U7, thereby switching the connection relationship between transducer J5 and transducer J6 and the "transmit signal (SIGNAL_TX) / receive signal (SIGNAL_RX)", realizing the time-division multiplexing of the "transmit mode" and "receive mode" of the two transducers. C33 is a power supply filter to stabilize the power supply of analog switch U7 and reduce the impact of power supply noise on the signal conversion of the transducers. Pull-down resistor R49 pulls the default level of Sel2 low. When there is no control signal, Sel2 is stably kept at a low level, ensuring the reliability of the transducer's transmit / receive mode switching logic.

[0029] Figure 4This is a multi-level adjustable signal amplification circuit. U4 is a 4-channel analog switch; in this specific implementation, a TMUX1204 analog switch is used. Pins 2, 4, 7, and 9 of U4 are connected to the inverting input pin 4 of operational amplifier U10 via resistors R24, R15, R23, and R27, respectively. Pin 3 of U4 is directly grounded. The enable pin 5 of U4 is connected to the shutdown pin 5 of operational amplifier U10 via resistor R68. The drain pin 8 of U4 is connected to the inverting input pin 4 of operational amplifier U10 via capacitor C39, and is directly connected to the output pin 1 of operational amplifier U10. The power supply pin 6 of U4 is connected to the input power supply VCC-RX. Pin 5 of U4 is connected to RxEn, which is the enable signal. U4 selects four different channels via control pins (A0, S1, S3, EN, etc.), and connects the corresponding feedback resistors (R15, R23, R24, R27) to the operational amplifier's feedback loop. Different resistors correspond to different gain levels, and the amplification factor is changed by connecting different resistors. Adaptive gain amplification is applied to the input signal, ensuring that weak signals are effectively amplified while preventing the signal from becoming too strong. Finally, the amplified signal is output to meet the requirements of subsequent signal processing.

[0030] The RxEn signal is used to control the enable of the amplifier circuit. Combined with the control signal of the four-channel analog switch, it enables switching of the multi-level gain of the output voltage signal SIGNAL_RX of the transducer operating circuit. U10 is a high-speed operational amplifier; in this specific implementation, an OPA838 operational amplifier is used. The inverting input pin 4 of U10 is connected to ground through resistor R60 and capacitor C40. The non-inverting input pin 3 of U10 is connected to the power supply through resistor R65 and resistor R66, grounded through resistor R67 and capacitor C45, and receives signals through capacitor C43. The positive power supply pin 6 of U10 is connected to the power supply and grounded through capacitor C41. The negative power supply pin 2 of U10 is connected to ground. The output pin 1 of U10 outputs a signal through resistor R63, resistor R64, and capacitor C42; the output pin 1 is then grounded through resistor R63 and capacitor C44.

[0031] U10, along with other resistors and capacitors, constitutes a non-inverting amplifier circuit, ensuring high-frequency signal amplification performance. When the RxEn signal controls the amplifier circuit, the signal is input to the non-inverting input through coupling capacitor C43. The DC bias at the non-inverting input is provided by a network composed of R65, R66, and C45, ensuring the operational amplifier operates in the linear region. The inverting input is connected to the output through a feedback resistor selected by an analog switch, forming negative feedback. The amplification factor of operational amplifier U10 is directly determined by the ratio of resistor R60 to the feedback resistor controlled by U4. Meanwhile, C41 and C46 serve as power supply filters, reducing power supply noise. C44 and C42 are used for high-frequency filtering or impedance matching of the output amplified signal. This circuit is effectively applicable to various application scenarios, allowing for the acquisition of the required signal strength by adjusting different amplification factors under varying conditions such as air temperature, humidity, and gas medium changes.

[0032] This utility model's boost power conversion circuit utilizes the alternating energy storage and release characteristics of inductors to achieve output voltage boosting. Simultaneously, through the synergistic effect of a field-effect transistor and a control signal, the output voltage is controlled, providing overcurrent protection. The boosted voltage supplies power to the transducer's operating circuit, which receives the ultrasonic signal captured by the transducer and converts it into a corresponding voltage signal, which is then output to a multi-level adjustable amplification signal circuit. This circuit employs a four-channel analog switch to dynamically adjust the feedback resistor value, thereby achieving adjustable amplifier gain. By selecting an appropriate amplification factor, the required signal strength is ensured, improving measurement accuracy and system stability.

Claims

1. An ultrasonic gas meter metering circuit, characterized in that... include: A boost power converter circuit is used to convert a low-voltage input power supply into a high-voltage output. The voltage output control circuit is connected to the boost power conversion circuit. The high voltage output is controlled by an external signal to determine whether to supply power to subsequent circuits. The transducer operating circuit includes two transducers and an analog switch. The analog switch is used to select the transmitting and receiving transducers for transmitting and receiving ultrasonic signals. The multi-level adjustable signal amplification circuit includes an operational amplifier and a four-channel analog switch. The received ultrasonic signal is switched by the four-channel analog switch to achieve adjustable gain through switching the feedback resistor. The output of the boost power conversion circuit is connected to the transducer working circuit via the voltage output control circuit, and the output signal of the transducer working circuit is sent to the multi-level adjustable amplification signal circuit.

2. The ultrasonic gas meter metering circuit according to claim 1, characterized in that... The boost power conversion circuit uses a boost chip U5, model TPS61096A. The boost chip U5 achieves voltage boosting through inductor L5, and achieves output voltage stabilization and filtering through feedback resistors R13 and R20, and capacitors C24 and C31.

3. The ultrasonic gas meter metering circuit according to claim 1, characterized in that... The voltage output control circuit includes field-effect transistors Q6 and Q7. The control signal Tx5vEn controls the conduction and cutoff of field-effect transistor Q7, thereby controlling the conduction state of field-effect transistor Q6 and realizing the switching control of VCC-TX voltage output.

4. The ultrasonic gas metering circuit according to claim 1, characterized in that... The analog switch U7 of the transducer working circuit is model TS12A44515. It selects one transducer as the transmitter and the other as the receiver through control signals Sel1 and Sel2.

5. The ultrasonic gas metering circuit according to claim 1, characterized in that... The multi-level adjustable signal amplification circuit includes: The four-channel analog switch U4, model number TMUX1204; Operational amplifier U10, model OPA838; Multiple feedback resistors are connected to different channels of the four-channel analog switch U4; Among them, the four-channel analog switch U4 selects different feedback resistors connected to the inverting input terminal of the operational amplifier U10 through the control signal to realize the switching of gain levels.

6. The ultrasonic gas metering circuit according to claim 5, characterized in that... The operational amplifier U10 forms a non-inverting amplifier circuit. Its positive input terminal receives the input signal through capacitor C43, and its inverting input terminal forms negative feedback with the output terminal through a selected feedback resistor.

7. The ultrasonic gas meter metering circuit according to claim 5 or 6, characterized in that... The feedback resistors are feedback resistor R15, feedback resistor R23, feedback resistor R24 ​​and feedback resistor R27.

8. The ultrasonic gas metering circuit according to claim 1, characterized in that... The multi-level adjustable amplification signal circuit also includes an enable control signal RxEn, which is used to control the shutdown and activation of operational amplifier U10.

9. The ultrasonic gas meter metering circuit according to claim 1, characterized in that... The boost power conversion circuit boosts the 3.0V input voltage to a 12V output.

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