Speed measurement system of hot-wire anemometer and control method thereof

Abstract

The invention discloses a speed measurement system of a hot-wire anemometer and a control method thereof, and the system comprises a bridge sensor module which comprises a bridge comprising a detection resistor, and when the resistance value of the detection resistor changes along with the wind speed, the voltage difference value of the output end of the bridge is larger than a difference value threshold value; the analog-to-digital conversion circuit is used for converting a voltage analog signal output by the bridge output end into a digital signal; the central processing module is connected with the analog-to-digital conversion circuit and is used for receiving the digital signal and generating a feedback signal based on the digital signal; and the digital-to-analog conversion circuit is used for converting the feedback signal into a bridge top voltage analog signal, inputting the bridge top voltage analog signal to the bridge, and adjusting the bridge top voltage of the bridge to enable the voltage difference value to be smaller than or equal to the difference value threshold value. According to the system, active closed-loop adjustment is realized through a high-speed digital signal processing mode, and compared with a previous negative feedback hot-wire anemometer, the stability of the system is improved, the requirements on the performance of system components are reduced, the anti-electromagnetic interference capability is improved, and measurement errors caused by environmental factors are reduced.

Description

Technical Field

[0001] This invention relates to the field of testing technology, and in particular to a speed measuring system and control method for a hot-wire anemometer. Background Technology

[0002] Hot-wire anemometers are high-precision fluid velocity measuring instruments based on the principle of thermal equilibrium, widely used in aerospace, meteorological monitoring, industrial ventilation, and automotive engineering. Their core function is to indirectly calculate fluid velocity by measuring the change in resistance caused by convective heat transfer in the fluid. Due to their advantages such as fast response, wide measurement range, and ability to measure turbulence parameters, hot-wire anemometers have become indispensable key equipment in fluid dynamics research and engineering practice.

[0003] Current hot-wire anemometer systems generally employ operational amplifiers (op-amps) to construct signal conditioning circuits. After the bridge becomes unbalanced due to wind speed changes at the sensing element, the analog signal output by the bridge is amplified, compared, and processed. A feedback signal is then generated based on this analog signal to adjust the bridge balance, which is a necessary condition for the speed measurement system. However, in complex electromagnetic environments, this method of generating feedback signals based on analog signals has significant limitations in its anti-interference capability. On the one hand, analog signals are susceptible to high-frequency electromagnetic interference (such as radio frequency radiation and power supply harmonics) during transmission and processing, leading to noise superposition in the feedback signal and causing fluctuations in the flow velocity measurement value. On the other hand, the common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR) of the op-amp are limited by device performance, making it difficult to effectively filter out conducted or coupled interference from the analog feedback signal generated. Furthermore, feedback regulation may fail due to negative feedback loop saturation, ultimately resulting in decreased accuracy and compromised stability of the speed measurement system.

[0004] Therefore, improving the measurement accuracy, stability, and environmental adaptability of hot-wire anemometers in complex electromagnetic environments is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a speed measurement system and control method for a hot-wire anemometer that overcomes or at least partially solves the above problems.

[0006] Firstly, a speed measurement system for a hot-wire anemometer is provided, comprising:

[0007] A bridge sensor module includes a bridge containing a detection resistor, wherein when the resistance of the detection resistor changes with wind speed, the voltage difference between the first output terminal and the second output terminal of the bridge is greater than a difference threshold.

[0008] An analog-to-digital converter circuit is connected to the first output terminal and the second output terminal of the bridge circuit, and is used to acquire the first voltage analog signal output from the first output terminal and the second voltage analog signal output from the second output terminal, and convert the first voltage analog signal into a first digital signal and the second voltage analog signal into a second digital signal.

[0009] A central processing module, connected to the analog-to-digital converter circuit, is used to receive the first digital signal and the second digital signal, and generate a feedback signal based on the first digital signal and the second digital signal;

[0010] A digital-to-analog converter circuit, connected to the input terminals of the central processing module and the bridge, is used to convert the feedback signal into an analog signal of the bridge top voltage and input it to the bridge, and adjust the bridge top voltage of the bridge so that the voltage difference is less than or equal to the difference threshold.

[0011] In some embodiments, the bridge includes a first resistor, a second resistor, a detection resistor, and a third resistor, wherein a first end of the first resistor is connected to a first end of the detection resistor, a second end of the first resistor is connected to a second end of the second resistor, a second end of the detection resistor is connected to a second end of the third resistor, and a first end of the third resistor is connected to a first end of the second resistor.

[0012] Wherein, the first end of the first resistor is the first output terminal of the bridge, the first end of the second resistor is the second output terminal of the bridge, the second end of the first resistor is the input terminal of the bridge, and the second end of the detection resistor is grounded.

[0013] In some embodiments, the bridge sensor module includes a digitally controlled potentiometer connected in parallel with the third resistor.

[0014] In some embodiments, the central processing module is connected to the digitally controlled potentiometer. The central processing module is used to send a resistance control signal to the digitally controlled potentiometer, and the digitally controlled potentiometer is used to receive the resistance control signal and adjust the equivalent resistance value of the third resistor based on the resistance control signal.

[0015] In some embodiments, the central processing module is used for:

[0016] The voltage difference is determined based on the first digital signal and the second digital signal. When the voltage difference is greater than the difference threshold, the target voltage value corresponding to the voltage difference is determined based on the pre-stored mapping relationship between the voltage difference and the target voltage value, and the feedback signal containing the target voltage value is generated.

[0017] The digital-to-analog converter circuit is used to receive the feedback signal and convert the feedback signal into an analog signal of the bridge top voltage, which is then input to the bridge to adjust the bridge top voltage value to the target voltage value.

[0018] In some embodiments, the analog-to-digital converter circuit is connected to the input terminal of the bridge circuit to acquire the bridge top voltage analog signal of the bridge circuit and convert the bridge top voltage analog signal into a third digital signal and send it to the central processing module.

[0019] The central processing module is used to receive the third digital signal, and after the voltage difference is less than or equal to the difference threshold, determine the actual voltage value of the bridge top voltage based on the third digital signal; and determine the wind speed corresponding to the actual voltage value of the bridge top voltage based on the pre-stored mapping relationship between the bridge top voltage value and the wind speed.

[0020] In some embodiments, the speed measurement system further includes a power amplifier circuit connected between the digital-to-analog converter circuit and the bridge sensor module, for amplifying the analog signal of the bridge top voltage.

[0021] In some embodiments, the speed measuring system further includes:

[0022] A square wave generating module is connected to the central processing module and the first output terminal of the bridge, and is used to receive the square wave excitation signal sent by the central processing module and transmit the square wave excitation signal to the bridge through the first output terminal.

[0023] In some embodiments, the speed measuring system further includes:

[0024] A data storage module, connected to the central processing module, is used to store the data processed by the central processing module;

[0025] A wireless communication module, connected to the central processing module, is used to realize wireless data transmission;

[0026] The communication interface module is connected to the central processing module and is used to provide the central processing module with a standardized hardware interface and protocol conversion function.

[0027] Secondly, a control method for a speed measuring system of a hot-wire anemometer is provided, applicable to the speed measuring system described in the first aspect, the method comprising:

[0028] The system receives a first digital signal and a second digital signal from an analog-to-digital converter (ADC). The first digital signal is converted from a first voltage analog signal output by the ADC based on the first output terminal of the bridge, and the second digital signal is converted from a second voltage analog signal output by the ADC based on the second output terminal of the bridge.

[0029] A feedback signal is generated based on the first digital signal and the second digital signal and sent to the digital-to-analog converter circuit. The digital-to-analog converter circuit is used to convert the feedback signal into an analog signal of the bridge top voltage and input it into the bridge. The bridge top voltage of the bridge is adjusted so that the voltage difference is less than or equal to the difference threshold.

[0030] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0031] This invention provides a hot-wire anemometer speed measurement system and its control method, which is achieved through hardware collaboration of a bridge sensor module, an analog-to-digital converter (ADC), a central processing module, and a digital-to-analog converter (DAC). The bridge sensor module converts wind speed changes into analog voltage signals. The ADC converts the analog signals into digital signals. The DAC, as the core hardware, processes the digital signals and generates feedback signals. The DAC converts the feedback signals back into analog signals to adjust the bridge voltage so that the voltage difference is less than or equal to a threshold value, ultimately achieving a balanced state. Compared to existing technologies that generate feedback signals based on analog signals, digital signals are less affected by high-frequency electromagnetic interference and power supply harmonics during transmission and processing, reducing feedback signal distortion caused by noise superposition and thus reducing fluctuations in flow velocity measurements. Furthermore, this system does not rely on the common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR) of operational amplifiers, effectively filtering out conducted or coupled interference and preventing feedback regulation failure due to negative feedback loop saturation. This ensures the reliable achievement of bridge balance, a necessary condition for speed measurement, thereby improving the measurement accuracy, stability, and environmental adaptability of the speed measurement system in complex electromagnetic environments. Improvements in hardware architecture have freed us from the reliance on the negative feedback mechanism of traditional operational amplifiers, thereby enhancing anti-interference capabilities and measurement performance at the hardware level.

[0032] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0033] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0034] Figure 1 This is a schematic diagram of the speed measurement system of a hot-wire anemometer provided in an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of a bridge circuit structure provided in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the speed measurement system of another hot-wire anemometer provided in an embodiment of the present invention;

[0037] Figure 4 This is a flowchart of a speed measurement system control method for a hot-wire anemometer provided in an embodiment of the present invention. Detailed Implementation

[0038] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to the accompanying drawings and specific implementation methods. It should be understood that the embodiments of this disclosure and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. Unless otherwise specified, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0039] Figure 1 This is a schematic diagram of the speed measurement system of a hot-wire anemometer provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the speed measurement system includes a bridge sensor module 10, an analog-to-digital converter circuit 20, a central processing module 30, and a digital-to-analog converter circuit 40.

[0040] The bridge sensor module 10 includes a bridge 11 containing a sensing resistor. When the resistance of the sensing resistor changes with wind speed, the voltage difference U between the first output terminal e1 and the second output terminal e2 of the bridge 11 is... e It is greater than the difference threshold.

[0041] The analog-to-digital converter circuit 20 is connected to the first output terminal e1 and the second output terminal e2 of the bridge 11. It acquires the first analog voltage signal output from the first output terminal e1 and the second analog voltage signal output from the second output terminal e2, converts the first analog voltage signal into a first digital signal, and converts the second analog voltage signal into a second digital signal. The central processing module 30 is connected to the analog-to-digital converter circuit 20, receives the first and second digital signals, and generates a feedback signal based on the first and second digital signals. The digital-to-analog converter circuit 40 is connected to the central processing module 30 and the input terminal e0 of the bridge 11. It converts the feedback signal into an analog voltage signal at the bridge top and inputs it to the bridge 11, adjusting the bridge top voltage U0 of the bridge 11 to achieve a voltage difference U0. e Less than or equal to the difference threshold.

[0042] It should be noted that the central processing module 30 provides an initial bridge top voltage to the bridge 11 through the digital-to-analog converter circuit 40, so that the bridge is in a balanced state, and the voltage difference between the first and second output terminals of the bridge is less than or equal to the difference threshold. When the resistance of the sensing resistor changes with the wind speed, the bridge becomes unbalanced, and the voltage difference between the first and second output terminals of the bridge exceeds the difference threshold. At this time, after receiving the first digital signal, the central processing module 30 can obtain the first voltage value output by the first output terminal of the voltage, and after receiving the second digital signal, it can obtain the second voltage value output by the second output terminal of the voltage, and determine the voltage difference based on the first and second voltage values; when the voltage difference exceeds the difference threshold, the central processing module 30 determines that the bridge is unbalanced and generates a feedback signal to be sent to the digital-to-analog converter circuit 40. The digital-to-analog converter circuit 40 converts the feedback signal into an analog signal of the bridge top voltage and inputs it to the bridge 11 to adjust the bridge top voltage U0 of the bridge 11. A change in the bridge voltage U0 at the top of the bridge causes a change in the current flowing through the sensing resistor in the bridge, which in turn causes a change in the temperature of the sensing resistor, and consequently a change in the resistance value of the sensing resistor, thus affecting the voltage difference U. e When the difference is less than or equal to the threshold, the bridge can return to a balanced state. This system achieves active closed-loop regulation through high-speed digital signal processing. Compared to previous negative feedback hot-wire anemometers, this improves system stability, reduces the performance requirements of system components, enhances electromagnetic interference resistance, reduces measurement errors caused by environmental factors, and also meets the requirement of rapid response to wind speed changes.

[0043] In this embodiment, the voltage difference U e This includes the magnitude and sign of the voltage difference.

[0044] For example, the sensing resistor R0 can be a hot wire sensor mounted on a high-precision resistance probe, which has a large temperature coefficient and good stability. When airflow passes through, the temperature and resistance value of the sensing resistor R0 change with the wind speed, thereby generating a differential voltage in the bridge 11, ultimately achieving wind speed measurement.

[0045] Figure 2 This is a schematic diagram of a bridge circuit structure provided in an embodiment of the present invention, as shown below. Figure 2 As shown, the bridge circuit includes a first resistor R1, a second resistor R2, a detection resistor R0, and a third resistor R3. The first end of the first resistor R1 is connected to the first end of the detection resistor R0, the second end of the first resistor R1 is connected to the second end of the second resistor R2, the second end of the detection resistor R0 is connected to the second end of the third resistor R3, and the first end of the third resistor R3 is connected to the first end of the second resistor R2.

[0046] Wherein, the first end of the first resistor R1 is the first output terminal e1 of the bridge 11, the first end of the second resistor R2 is the second output terminal e2 of the bridge 11, the second end of the first resistor R1 is the input terminal e0 of the bridge 11, and the second end of the detection resistor R0 is grounded.

[0047] In this embodiment, the first resistor R1, the second resistor R2, the detection resistor R0, and the third resistor R3 constitute a Wheatstone bridge. The first resistor R1 and the second resistor R2 are both fixed resistors, and the third resistor R3 is an adjustable resistor.

[0048] In some embodiments, the bridge sensor module 10 includes a digitally controlled potentiometer connected in parallel with the third resistor R3. The digitally controlled potentiometer allows for precise adjustment of the equivalent resistance value of the third resistor R3 via digital control. This design accurately determines the overheat ratio of the bridge 11, thereby precisely controlling the operating temperature of the sensing resistor R0. This is crucial for ensuring the accuracy of wind speed measurement, as the operating temperature of the sensing resistor R0 directly affects the sensitivity and linearity of its resistance value as a function of wind speed.

[0049] In some embodiments, the central processing module 30 is connected to the digitally controlled potentiometer 12. The central processing module 30 sends a resistance control signal to the digitally controlled potentiometer 12, and the digitally controlled potentiometer 12 receives the resistance control signal and adjusts the equivalent resistance value of the third resistor R3 based on the resistance control signal. Adjusting the equivalent resistance value of the third resistor via digital control, compared to a traditional mechanically adjustable resistor, allows for a faster and more stable response to the control commands of the central processing module. Furthermore, its digital control characteristics are compatible with the digital circuit design of the entire system (such as the central processing module and analog-to-digital / digital-to-analog converter circuits), reducing errors in the analog adjustment stage, improving adjustment accuracy and stability, and further enhancing the system's stability and anti-interference capability in complex environments.

[0050] It should be noted that the resistance of the digitally controlled potentiometer and the third resistor connected in parallel is the equivalent resistance of the third resistor. By adjusting the equivalent resistance value of the third resistor R3, the bridge 11 can reach an initial balanced state. At this time, the voltage difference U between the first voltage output from the first output terminal e1 and the second voltage output from the second output terminal e2 in the bridge 11 is... e The voltage difference is less than or equal to a preset threshold value (e.g., 0.00001V). This process determines the operating temperature of the sensing resistor R0 because the overheat ratio of bridge 11 is determined by the resistance of the bridge arms. Changes in the equivalent resistance of the third resistor R3 alter the overheat ratio, thus setting the heating temperature of the sensing resistor R0. When the wind speed changes, the airflow carries away the heat from the sensing resistor R0, causing a change in its resistance, disrupting the original balance of bridge 11, and causing the voltage difference U to... e The difference is greater than a preset threshold. Through this mechanism, the bridge 11 can convert wind speed changes into measurable electrical signals, providing a basis for subsequent wind speed calculations. After the bridge 11 reaches its initial equilibrium state, the central processing module 30 can provide the initial bridge top voltage to the bridge 11 through the digital-to-analog converter circuit 40. By precisely adjusting the equivalent resistance value of the third resistor R3 to achieve circuit balancing, the long-term stability and measurement accuracy of the system can be improved from a hardware perspective.

[0051] Optionally, the digitally controlled potentiometer 12 is an AD5272 digitally controlled potentiometer. The AD5272 digitally controlled potentiometer has high accuracy and stability, and small size, which is conducive to adapting to the miniaturization design requirements of modules.

[0052] In some embodiments, the central processing module 30 is used to determine the voltage difference based on the first digital signal and the second digital signal. When the voltage difference is greater than a difference threshold, it determines the target voltage value corresponding to the voltage difference based on a pre-stored mapping relationship between the voltage difference and the target voltage value, and generates a feedback signal containing the target voltage value. The digital-to-analog converter circuit 40 is used to receive the feedback signal and convert it into an analog signal of the bridge top voltage, which is then input to the bridge 11 to adjust the voltage value of the bridge top voltage U0 of the bridge 11 to the target voltage value.

[0053] In the above embodiment, the bridge top voltage U0 of the bridge 11 is precisely adjusted through an active closed-loop feedback mechanism. When the bridge 11 generates a voltage difference U exceeding the difference threshold due to wind speed changes, the adjustment is made accordingly. e At this time, the central processing module 30 quickly determines the target voltage value and generates a feedback signal based on the pre-stored mapping relationship between the voltage difference and the target voltage value. After being converted into an analog signal by the digital-to-analog converter circuit 40, the bridge top voltage U0 is directly adjusted, which can quickly rebalance the bridge 11, ensuring the real-time performance and accuracy of wind speed measurement and avoiding the influence of voltage difference U0. e Measurement errors caused by persistence.

[0054] It should be noted that the voltage difference Ue includes both the magnitude and the sign of the difference. When Ue is positive, the bridge top voltage needs to be increased to the target voltage value; for example, this can be achieved by increasing the initial bridge top voltage to reach the target value. When Ue is negative, the bridge top voltage needs to be decreased to the target voltage value; for example, this can be achieved by decreasing the initial bridge top voltage to reach the target value. The adjustment coefficient of the bridge top voltage is related to the magnitude of the voltage difference Ue. When Ue is large, the adjustment coefficient can be increased to quickly adjust the bridge top voltage to the target value; when Ue is small, the adjustment coefficient can be decreased to gradually approach the target value. This adjustment method can prevent over-adjustment from causing the bridge top voltage to oscillate back and forth, while also improving the convergence speed. The correspondence between the bridge top voltage and Ue can be determined through pre-calibration.

[0055] In some embodiments, the analog-to-digital converter 20 is connected to the input terminal e0 of the bridge 11, and is used to acquire the analog signal of the bridge top voltage of the bridge 11, and convert the analog signal of the bridge top voltage into a third digital signal and send it to the central processing module 30. The central processing module 30 is used to receive the third digital signal, and after the voltage difference is less than or equal to the difference threshold, determine the actual voltage value of the bridge top voltage U0 based on the third digital signal; and determine the wind speed corresponding to the actual voltage value of the bridge top voltage U0 based on the pre-stored mapping relationship between the voltage value of the bridge top voltage U0 and the wind speed.

[0056] It should be noted that the mapping relationship between the voltage difference and the target voltage value, as well as the mapping relationship between the bridge top voltage value and the wind speed, which are pre-stored in the central processing module 30, can be pre-calibrated. For example, by measuring the balanced bridge top voltage under different wind speeds, the functional relationship between the bridge top voltage value and the wind speed can be obtained. This functional relationship can be stored in the central processing module 30. When measuring other wind speeds, the corresponding wind speed can be obtained based on this functional relationship and the actual obtained bridge top voltage value, thereby completing the wind speed measurement.

[0057] For example, the central processing module 30 also stores a digital filtering algorithm and a resolution adjustment algorithm. The digital filtering algorithm can filter the received digital signal to remove noise interference; the resolution adjustment algorithm allows the speed measurement system to flexibly adjust the resolution of the measured wind speed results according to user needs.

[0058] In some embodiments, the speed measurement system further includes a power amplifier circuit 50, which is connected between the digital-to-analog converter circuit 20 and the bridge sensor module 10, and is used to amplify the analog signal of the bridge top voltage.

[0059] In some embodiments, the speed measurement system further includes a square wave generation module 60, which is connected to the central processing module 30 and the first output terminal of the bridge 11. The square wave generation module 60 is used to receive the square wave excitation signal sent by the central processing module 30 and transmit the square wave excitation signal to the bridge 11. The central processing module 30 is used to generate a square wave excitation signal and send it to the square wave generation module 60.

[0060] By transmitting the square wave excitation signal to the bridge 11, a disturbance is generated in the bridge, causing the voltage difference to exceed the difference threshold. The central processing module 30 can judge the response capability and stability of the speed measurement system based on the changes in the received digital signal. Thus, by adjusting the adjustment coefficient of the bridge top voltage, the dynamic performance of the system can be optimized, ensuring that the bridge 11 can quickly reach equilibrium when the wind speed changes, thereby improving the measurement accuracy and response speed of the speed measurement system.

[0061] For example, the central processing module 30 monitors the voltage difference and the amplitude and speed of the change in the bridge top voltage based on the received digital signal; if the signal fluctuation exceeds the preset range, it indicates that the system is unstable and the bridge top voltage adjustment coefficient needs to be reduced; if the signal changes slowly and the response time is long, it indicates that the system response capability is poor and the bridge top voltage adjustment coefficient needs to be increased to optimize the response speed.

[0062] Figure 3 This is a schematic diagram of the structure of another hot-wire anemometer speed measurement system provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the central processing module 30 is an STM32 microcontroller, the analog-to-digital conversion circuit 20 uses an AD7616 analog-to-digital converter, and the digital-to-analog conversion circuit 40 uses a DAC8830 digital-to-analog converter.

[0063] It should be noted that hot-wire anemometers typically include three bridge sensor modules 10 ( Figure 3 (Only two are shown in the image), used to detect wind speed in different directions. The AD7616 analog-to-digital converter includes eight channels. Channels 1, 2, and 3 are connected to the first output, second output, and input terminals of a bridge 11 to obtain a first voltage analog signal, a second voltage analog signal, and a third voltage analog signal. Channels 4, 5, and 6 are connected to the first output, second output, and input terminals of another bridge 11 to obtain the first voltage analog signal, the second voltage analog signal, and the third voltage analog signal.

[0064] In some embodiments, the speed measurement system further includes a data storage module 70, a wireless communication module 80, and a communication interface module 90.

[0065] The data storage module 70 is connected to the central processing module 30 and is used to store data processed by the central processing module 30, such as detected wind speed data, to achieve local storage functionality. The wireless communication module 80 is connected to the central processing module 30 and is used to achieve wireless data transmission. The communication interface module 90 is connected to the central processing module 30 and is used to provide a standardized hardware interface and protocol conversion function for the central processing module 30.

[0066] The data storage module 70 uses non-volatile memory chips (such as flash memory), and its storage capacity can be selected according to actual needs, facilitating users to query and analyze historical data later. When wireless transmission is unavailable, it can work with the system to locally store offline measurement data. The wireless communication module 80 uses common wireless communication technologies such as Bluetooth, Wi-Fi, ZigBee, or 4G / 5G communication modules, enabling wireless transmission of processed wind speed data to external devices (such as mobile phones, tablets, remote monitoring centers, etc.), meeting the needs of measurement scenarios requiring wireless operation, such as UAV meteorological monitoring and portable environmental measurement instruments. The communication interface module 90 can select traditional wired communication interfaces such as USB, RS-485, and CAN interfaces. Besides providing standardized hardware interfaces and protocol conversion functions, it can also work with the wireless communication module 80 to provide multiple options for data transmission, meeting different communication needs, such as supporting data interaction and system updates with a host computer via serial port. The inclusion of these modules greatly expands the application scope of the speed measurement system.

[0067] In this embodiment, the speed measurement system also includes a power supply module for supplying power to the various modules and circuits within the system. The power supply module includes a multi-stage power filtering circuit to reduce power supply noise and meet the requirements for high-frequency, small-fluctuation wind speed measurement in complex scenarios. For example, the multi-stage power filtering circuit can convert 12V to 6.5V, then to 5V, and finally to 3.3V. Through multiple voltage reduction steps, each reduction filters out a portion of the noise.

[0068] In this embodiment, the various modules and circuits in the speed measurement system (including the bridge sensor module 10, analog-to-digital converter circuit 20, central processing module 30, digital-to-analog converter circuit 40, power amplifier circuit 50, square wave generator module 60, data storage module 70, wireless communication module 80, and communication interface module 90) are integrated on the same PCB board using high-density integrated circuit packaging technology. This not only significantly reduces the overall size of the speed measurement system and improves its integration level, but also better adapts to application scenarios with demanding space requirements. Simultaneously, this integration method helps optimize circuit layout, and with a reasonable shielding design, it enhances the speed measurement system's resistance to electromagnetic interference, enabling it to operate stably in complex electromagnetic environments.

[0069] For example, the above circuit modules are integrated on a PCB board with dimensions of 200mm×200mm×5mm.

[0070] Based on the same inventive concept, embodiments of the present invention also provide a control method for a speed measurement system of a hot-wire anemometer. Figure 4 This is a flowchart of a speed measurement system control method for a hot-wire anemometer provided in an embodiment of the present invention, as shown below. Figure 4 As shown, the method includes:

[0071] Step S110: Receive the first digital signal and the second digital signal sent by the analog-to-digital converter circuit. The first digital signal is converted from the first voltage analog signal output by the analog-to-digital converter circuit based on the first output terminal of the bridge, and the second digital signal is converted from the second voltage analog signal output by the analog-to-digital converter circuit based on the second output terminal of the bridge.

[0072] Step S120: Generate a feedback signal based on the first digital signal and the second digital signal and send it to the digital-to-analog converter circuit. The digital-to-analog converter circuit is used to convert the feedback signal into an analog signal of the bridge top voltage and input it into the bridge. Adjust the bridge top voltage of the bridge so that the voltage difference is less than or equal to the difference threshold.

[0073] It should be noted that the execution entity of the above control method can be the central processing module described in the above embodiments. The central processing module 30 provides an initial bridge top voltage to the bridge 11 through the digital-to-analog converter circuit 40, so that the bridge is in a balanced state, and the voltage difference between the first output terminal and the second output terminal of the bridge is less than or equal to the difference threshold. When the resistance of the detection resistor changes with the wind speed, the bridge becomes unbalanced, and the voltage difference between the first output terminal and the second output terminal of the bridge is greater than the difference threshold. At this time, after receiving the first digital signal, the central processing module 30 can obtain the first voltage value output by the first output terminal of the voltage, and after receiving the second digital signal, it can obtain the second voltage value output by the second output terminal of the voltage, and determine the voltage difference based on the first voltage value and the second voltage value; when the voltage difference is greater than the difference threshold, the central processing module 30 determines that the bridge is unbalanced at this time, and generates a feedback signal to be sent to the digital-to-analog converter circuit 40. The digital-to-analog converter circuit 40 converts the feedback signal into a bridge top voltage analog signal and inputs it to the bridge 11 to adjust the bridge top voltage U0 of the bridge 11. A change in the bridge voltage U0 at the top of the bridge causes a change in the current flowing through the sensing resistor in the bridge, which in turn causes a change in the temperature of the sensing resistor, and consequently a change in the resistance value of the sensing resistor, thus affecting the voltage difference U. e If the difference is less than or equal to the threshold, the bridge can be restored to a balanced state.

[0074] In some embodiments, step S120, generating a feedback signal based on the first digital signal and the second digital signal, includes:

[0075] The voltage difference is determined based on the first digital signal and the second digital signal. When the voltage difference is greater than the difference threshold, the target voltage value corresponding to the voltage difference is determined based on the pre-stored mapping relationship between the voltage difference and the target voltage value, and a feedback signal containing the target voltage value is generated.

[0076] In some embodiments, before performing steps S110-S120 above, the control method further includes:

[0077] A resistance control signal is sent to the digitally controlled potentiometer. The resistance control signal is used to instruct the digitally controlled potentiometer to adjust the equivalent resistance value of the third resistor based on the resistance control signal, so that the bridge reaches the initial balance state.

[0078] In some embodiments, before performing steps S110-S120 above, the control method further includes:

[0079] A square wave excitation signal is generated and sent to the square wave generation module, so that the square wave generation module transmits the square wave excitation signal to the bridge to generate a disturbance to the bridge, so that the voltage difference is greater than the difference threshold.

[0080] Based on the received digital signal, the voltage difference and the amplitude and rate of change of the bridge top voltage are monitored. If the amplitude or rate of change exceeds the preset range, the adjustment coefficient of the bridge top voltage is adjusted to generate a bridge top voltage adjustment signal and send it to the analog-to-digital conversion circuit. The bridge top voltage adjustment signal is used to instruct the analog-to-digital conversion circuit to adjust the voltage value of the bridge top voltage input to the bridge input terminal based on the bridge top voltage adjustment signal.

[0081] In some embodiments, the control method further includes:

[0082] The circuit receives a third digital signal from the analog-to-digital converter (ADC) circuit. If the voltage difference is less than or equal to a threshold value, it determines the actual voltage value of the bridge top voltage U0 based on the third digital signal. Based on a pre-stored mapping relationship between the bridge top voltage U0 and wind speed, it determines the wind speed corresponding to the actual bridge top voltage U0. The third digital signal is generated by the ADC circuit from the analog signal of the bridge top voltage input to the bridge.

[0083] It should be noted that the mapping relationship between the voltage difference and the target voltage value, as well as the mapping relationship between the bridge top voltage and the wind speed, which are pre-stored in the central processing module 30, can be pre-calibrated.

[0084] In some embodiments, the control method further includes:

[0085] The received digital signal is filtered based on a pre-stored digital filtering algorithm to remove noise interference.

[0086] The technical solutions provided in the above embodiments of this application have at least the following technical effects or advantages:

[0087] This invention provides a hot-wire anemometer speed measurement system and its control method, which is achieved through hardware collaboration of a bridge sensor module, an analog-to-digital converter (ADC), a central processing module, and a digital-to-analog converter (DAC). The bridge sensor module converts wind speed changes into analog voltage signals. The ADC converts the analog signals into digital signals. The DAC, as the core hardware, processes the digital signals and generates feedback signals. The DAC converts the feedback signals back into analog signals to adjust the bridge voltage so that the voltage difference is less than or equal to a threshold value, ultimately achieving a balanced state. Compared to existing technologies that generate feedback signals based on analog signals, digital signals are less affected by high-frequency electromagnetic interference and power supply harmonics during transmission and processing, reducing feedback signal distortion caused by noise superposition and thus reducing fluctuations in flow velocity measurements. Furthermore, this system does not rely on the common-mode rejection ratio (CMRR) and power supply rejection ratio (PSRR) of operational amplifiers, effectively filtering out conducted or coupled interference and preventing feedback regulation failure due to negative feedback loop saturation. This ensures the reliable achievement of bridge balance, a necessary condition for speed measurement, thereby improving the measurement accuracy, stability, and environmental adaptability of the speed measurement system in complex electromagnetic environments. Improvements in hardware architecture have freed us from the reliance on the negative feedback mechanism of traditional operational amplifiers, thereby enhancing anti-interference capabilities and measurement performance at the hardware level.

[0088] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0089] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0090] It should be noted that the above embodiments are illustrative of the invention and not restrictive of the invention, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims.

Claims

1. A speed measurement system for a hot-wire anemometer, characterized in that, include: A bridge sensor module includes a bridge containing a detection resistor, wherein when the resistance of the detection resistor changes with wind speed, the voltage difference between the first output terminal and the second output terminal of the bridge is greater than a difference threshold. An analog-to-digital converter circuit is connected to the first output terminal and the second output terminal of the bridge circuit, and is used to acquire the first voltage analog signal output from the first output terminal and the second voltage analog signal output from the second output terminal, and convert the first voltage analog signal into a first digital signal and the second voltage analog signal into a second digital signal. A central processing module, connected to the analog-to-digital converter circuit, is used to receive the first digital signal and the second digital signal, and generate a feedback signal based on the first digital signal and the second digital signal; A digital-to-analog converter circuit, connected to the input terminals of the central processing module and the bridge, is used to convert the feedback signal into an analog signal of the bridge top voltage and input it to the bridge, and adjust the bridge top voltage of the bridge so that the voltage difference is less than or equal to the difference threshold.

2. The speed measuring system according to claim 1, characterized in that, The bridge circuit includes a first resistor, a second resistor, a detection resistor, and a third resistor. The first end of the first resistor is connected to the first end of the detection resistor, the second end of the first resistor is connected to the second end of the second resistor, the second end of the detection resistor is connected to the second end of the third resistor, and the first end of the third resistor is connected to the first end of the second resistor. Wherein, the first end of the first resistor is the first output terminal of the bridge, the first end of the second resistor is the second output terminal of the bridge, the second end of the first resistor is the input terminal of the bridge, and the second end of the detection resistor is grounded.

3. The speed measuring system according to claim 2, characterized in that, The bridge sensor module includes a digitally controlled potentiometer connected in parallel with the third resistor.

4. The speed measuring system according to claim 3, characterized in that, The central processing module is connected to the digitally controlled potentiometer. The central processing module is used to send a resistance control signal to the digitally controlled potentiometer. The digitally controlled potentiometer is used to receive the resistance control signal and adjust the equivalent resistance value of the third resistor based on the resistance control signal.

5. The speed measuring system according to claim 1, characterized in that, The central processing module is used for: The voltage difference is determined based on the first digital signal and the second digital signal. When the voltage difference is greater than the difference threshold, the target voltage value corresponding to the voltage difference is determined based on the pre-stored mapping relationship between the voltage difference and the target voltage value, and the feedback signal containing the target voltage value is generated. The digital-to-analog converter circuit is used to receive the feedback signal and convert the feedback signal into an analog signal of the bridge top voltage, which is then input to the bridge to adjust the bridge top voltage value to the target voltage value.

6. The speed measuring system according to claim 1, characterized in that, The analog-to-digital converter circuit is connected to the input terminal of the bridge circuit and is used to acquire the bridge top voltage analog signal of the bridge circuit and convert the bridge top voltage analog signal into a third digital signal and send it to the central processing module. The central processing module is used to receive the third digital signal and, after the voltage difference is less than or equal to the difference threshold, determine the actual voltage value of the bridge top voltage based on the third digital signal; Based on the pre-stored mapping relationship between the voltage value of the bridge top voltage and the wind speed, the wind speed corresponding to the actual voltage value of the bridge top voltage is determined.

7. The speed measuring system according to claim 1, characterized in that, The speed measurement system also includes a power amplifier circuit, which is connected between the digital-to-analog converter circuit and the bridge sensor module, and is used to amplify the analog signal of the bridge top voltage.

8. The speed measuring system according to claim 1, characterized in that, The speed measurement system also includes: A square wave generating module is connected to the central processing module and the first output terminal of the bridge, and is used to receive the square wave excitation signal sent by the central processing module and transmit the square wave excitation signal to the bridge through the first output terminal.

9. The speed measuring system according to claim 1, characterized in that, The speed measurement system also includes: A data storage module, connected to the central processing module, is used to store the data processed by the central processing module; A wireless communication module, connected to the central processing module, is used to realize wireless data transmission; The communication interface module is connected to the central processing module and is used to provide the central processing module with a standardized hardware interface and protocol conversion function.

10. A control method for a speed measurement system of a hot-wire anemometer, characterized in that, The method, applicable to any one of claims 1 to 9, comprises: The system receives a first digital signal and a second digital signal from an analog-to-digital converter (ADC). The first digital signal is converted from a first voltage analog signal output by the ADC based on the first output terminal of the bridge, and the second digital signal is converted from a second voltage analog signal output by the ADC based on the second output terminal of the bridge. A feedback signal is generated based on the first digital signal and the second digital signal and sent to the digital-to-analog converter circuit. The digital-to-analog converter circuit is used to convert the feedback signal into an analog signal of the bridge top voltage and input it into the bridge. The bridge top voltage of the bridge is adjusted so that the voltage difference is less than or equal to the difference threshold.

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