Detection circuit and method of LC resonant transducer

Abstract

The invention provides a detection circuit of an LC resonant transducer. The detection circuit comprises an FPGA-based SoPC system, a pulse generator, a transmitting coil, a reading coil and an analog-to-digital converter, the FPGA-based SoPC system controls the pulse generator to generate an excitation signal via the transmitting coil, the LC resonant transducer absorbs energy of the excitation signal and generates an attenuation signal via induction, the attenuation signal is received by the reading coil and sampled by the analog-to-digital converter, the FPGA-based SoPC system calculates a frequency spectrum of output signals of the LC resonant transducer via DFT, and the resonant frequency is detected. The invention also provides a detection method of the detection circuit of the LC resonant transducer. The frequency spectrum of the output signals of the LC resonant transducer is obtained, and a resonant frequency of the LC resonant transducer is obtained via a peak value detection algorithm. According to the detection circuit and method, complexity and excitation signals of the detection circuit of the LC resonant transducer have less interference in the transducer signals, and the measuring speed and portability are improved.

Description

technical field [0001] The invention relates to the field of sensor detection, in particular to a detection circuit and a detection method of an LC resonant sensor. Background technique [0002] The core component of the LC resonant sensor is an LC resonant circuit composed of an inductance and a capacitor in series, in which the inductance or capacitance is used as a sensitive unit to sense the measured (for example: pressure, temperature, chemical quantity, etc.), and the measured value is converted into an LC resonant circuit the resonant frequency. In order to obtain the LC resonant sensor signal, the detection circuit needs to be matched with it. figure 1 It is a commonly used LC resonant sensor detection circuit in the prior art. Its detection principle is mainly based on the impedance change method, that is, using the frequency characteristics of the equivalent input impedance of the sensor and the read coil (amplitude-frequency, phase-frequency, real part- frequenc...

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Problems solved by technology

[0004] According to the working principle of the LC resonant sensor, a high-precision network analyzer is often used in the laboratory to measure the impedance phase spectrum of the reading coil, and the resonant frequency of the sensor is detected from the impedance phase spectrum, but the network analyzer is large in size and equipment Heavy, high cost, due to the limitations of the above-mentioned volume, cost and other aspects of the network analyzer, it is difficult to apply it in actual detection

The closed-loop detection circuit proposed by M.Nowak et al. is to measure the resonant frequency of the sensor by locking the position where the impedance phase of the read coil is zero; the detection circuit based on the voltage-controlled oscillator (VCO) proposed by J.Coosemans et al. Control the VCO output sweep signal to measure the frequency characteristics of the input impedance of the read coil, so as to realize the measurement of the sensor resonance frequency; however, for the LC resonance sensor with high resonance frequency, it is difficult to achieve a stable closed loop by using the closed-loop circuit detection method; The frequency sweep signal quality (amplitude consistency, frequency interval, etc.) generated by the VCO detection method is poor, and the detection speed is slow

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