A vortex flowmeter frequency acquisition circuit

Abstract

This invention relates to the field of instrumentation circuit technology, and more particularly to a frequency acquisition circuit for a vortex flowmeter. The circuit includes an MCU control circuit, a frequency acquisition circuit, and a current amplification circuit. The frequency acquisition circuit is used to acquire frequency signals and is electrically connected to the MCU control circuit. It is used to calculate and store the frequency signals. The current amplification circuit is used to amplify the current of the frequency signals and is also electrically connected to the MCU control circuit. It is used to perform a Fast Fourier Transform (FFT) on the amplified frequency signals within the MCU control circuit. This invention improves the accuracy of frequency acquisition and thus enhances measurement precision by having one path of the frequency signal Fi pass through the frequency acquisition circuit and then enter the MCU's TIM1 pin for calculation and data storage, while another path amplifies the frequency Fi and then enters the MCU's ADC5 pin for FFT conversion.

Description

Technical Field

[0001] This invention belongs to the field of instrumentation circuit technology, specifically relating to a frequency acquisition circuit for a vortex flowmeter. Background Technology

[0002] The vortex flow meters currently used in the market have increasingly higher requirements for accuracy, and one aspect of improving accuracy is the accurate measurement of frequency acquisition. In view of this, we propose a frequency acquisition circuit for vortex flow meters. Summary of the Invention

[0003] The purpose of this invention is to address the limitations of existing ultravortex flowmeter frequency acquisition circuits and improve the accuracy of data acquisition by proposing a vortex flowmeter frequency acquisition circuit and battery pack architecture.

[0004] The technical solution adopted in the present invention is as follows:

[0005] One aspect provides a frequency acquisition circuit for a vortex flowmeter, including an MCU control circuit, a frequency acquisition circuit, and a current amplification circuit. The frequency acquisition circuit is used to acquire frequency signals and is electrically connected to the MCU control circuit. It is used to calculate and store the frequency signals. The current amplification circuit is used to amplify the current of the frequency signals and is electrically connected to the MCU control circuit. It is used to perform a fast Fourier transform on the amplified frequency signals within the MCU control circuit.

[0006] As a preferred embodiment of the present invention, the frequency acquisition circuit includes a voltage divider circuit composed of resistors R2 and R4, a field-effect transistor Q1, resistors R1 and R3, and an ESD protection diode E1.

[0007] As a preferred embodiment of the present invention: the frequency signal enters from the voltage divider circuit composed of resistors R2 and R4, resistor R2 is connected to the gate of the field-effect transistor Q1, resistor R4 is connected to the source of the field-effect transistor Q1, the drain of the field-effect transistor Q1 is connected to resistors R1 and R3 respectively, resistor R3 is connected to the ESD protection diode E1 and then connected to the TIMI pin of the MCU control circuit, and resistor R1 is connected to a 3.3V power supply.

[0008] As a preferred embodiment of the present invention, the current amplification circuit includes a voltage divider circuit composed of capacitor C3, resistor R5 and resistor R6, operational amplifier U2 and capacitor C4.

[0009] As a preferred embodiment of the present invention: the frequency signal enters from the capacitor C3, the output terminal of the capacitor C3 is connected to the resistor R5, the resistor R5 is connected to the input terminal of the operational amplifier U2, the 3.3V power supply is connected to the capacitor C4 and the VCC pin of the operational amplifier U2 respectively, and the output terminal of the operational amplifier U2 is connected to the ADC5 pin of the MCU control circuit.

[0010] The vortex flowmeter frequency acquisition circuit of the present invention improves the frequency acquisition accuracy and thus improves the measurement precision by passing the frequency signal Fi through the frequency acquisition circuit to the TIM1 pin of the MCU for calculation and data storage, and by amplifying the frequency Fi with current before passing it to the ADC5 pin of the MCU for FFT conversion. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the circuit block of the present invention;

[0012] Figure 2 This is a schematic diagram of the frequency acquisition circuit of the present invention;

[0013] Figure 3 This is a schematic diagram of the current amplifier circuit of the present invention;

[0014] Figure 4 This is a schematic diagram of the MCU control circuit of the present invention. Detailed Implementation

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in this embodiment can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0016] Reference Figure 1-4 A preferred embodiment of the present invention provides a frequency acquisition circuit for a vortex flowmeter, comprising three parts: an MCU control circuit, a frequency acquisition circuit, and a current amplification circuit.

[0017] The analog signal acquired in the current amplifier circuit is amplified by the operational amplifier and then enters the ADC pin of the MCU control circuit for FFT (Fast Fourier Transform). According to the Nyquist sampling principle, the sampling frequency fs must be greater than or equal to twice the highest frequency of the signal to avoid aliasing. Therefore, the highest frequency that fs can sample is fs / 2. When the microcontroller performs FFT on the sampling frequency, it takes n points in the time domain to perform spectral analysis on the sampled signal, which means dividing the digital frequency W into n parts. Only by knowing the original sampling frequency fs can the actual frequency corresponding to each n points be determined, thus deriving the actual frequency.

[0018] Therefore, a frequency acquisition circuit is used to acquire and calculate the frequency signal to obtain an accurate actual frequency value, and the frequency value is stored in the microcontroller for FFT transformation.

[0019] Specifically, the MCU control circuit uses the STM32F103CBT6 microcontroller.

[0020] Among them, Figure 1 As shown, the frequency signal Fi passes through the frequency acquisition circuit and then enters the TIM1 pin of the MCU control circuit for calculation and data storage. The other path amplifies the frequency Fi and then enters the ADC5 pin of the MCU control circuit for FFT conversion.

[0021] In the frequency acquisition circuit, such as Figure 2 As shown, the analog signal Fi is attenuated by the voltage divider circuit of resistors R2 and R4, and enters the gate of the field-effect transistor Q1 to control the MOSFET switch. The drain of the field-effect transistor Q1 is connected to the power supply of 3.3V through the pull-up resistor R1. Another path enters the TIM1 pin of the MCU control circuit through the current limiting resistor R3. An ESD protection diode is connected in parallel at the TIM1 pin of the MCU control circuit for electrostatic protection.

[0022] In the current amplification circuit, such as Figure 3 As shown, the frequency signal Fi is attenuated by the voltage divider circuit of resistors R5 and R6 after passing through the DC blocking capacitor C3. It then enters the operational amplifier U2 to amplify the current. The capacitor C4 at the 3.3V power supply of the operational amplifier U2 is a filter capacitor. The output pin of the operational amplifier U2 is connected to the ADC5 pin of the MCU control circuit.

[0023] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0024] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A frequency acquisition circuit for a vortex flowmeter, characterized in that: It includes an MCU control circuit, a frequency acquisition circuit, and a current amplification circuit. The frequency acquisition circuit is used to acquire frequency signals and is electrically connected to the MCU control circuit. It is used to calculate and store the frequency signals. The current amplification circuit is used to amplify the current of the frequency signals and is electrically connected to the MCU control circuit. It is used to perform a fast Fourier transform on the amplified frequency signals within the MCU control circuit. The frequency signal passes through the frequency acquisition circuit and then enters the TIM1 pin of the MCU control circuit for calculation and data storage. The other path amplifies the frequency signal and then enters the ADC5 pin of the MCU control circuit for FFT conversion. The frequency acquisition circuit includes a voltage divider circuit composed of resistors R2 and R4, a field-effect transistor Q1, resistors R1 and R3, and an ESD protection diode E1. The frequency signal enters from the voltage divider circuit composed of resistors R2 and R4. Resistor R2 is connected to the gate of the field-effect transistor Q1, resistor R4 is connected to the source of the field-effect transistor Q1, the drain of the field-effect transistor Q1 is connected to resistors R1 and R3 respectively, resistor R3 is connected to the ESD protection diode E1 and then connected to the TIMI pin of the MCU control circuit, and resistor R1 is connected to a 3.3V power supply. The current amplification circuit includes a voltage divider circuit composed of capacitor C3, resistor R5 and resistor R6, operational amplifier U2 and capacitor C4. The frequency signal enters through capacitor C3, the output terminal of capacitor C3 is connected to resistor R5, resistor R5 is connected to the input terminal of operational amplifier U2, the 3.3V power supply is connected to capacitor C4 and the VCC pin of operational amplifier U2 respectively, and the output terminal of operational amplifier U2 is connected to the ADC5 pin of the MCU control circuit.

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