A method for optimizing resonant frequency detection

Abstract

The present invention discloses a method for optimizing resonant frequency detection. By comparing the results of two adjacent same-direction frequency sweeps, the measurement error caused by the fluctuation of the measurement to be measured during the frequency sweep is effectively reduced; the frequency sweep range and step are dynamically adjusted according to the detection results, which not only ensures that the system can operate effectively, but also solves the contradiction between the detection time and the frequency sweep range and step; the direction-alternating frequency sweep scheme is adopted to offset the system's delay error. Under ideal conditions, the system delay is fixed, and the offset of the resonant frequency is equal in the two frequency sweep directions.

Description

Technical Field

[0001] The invention belongs to the field of sensor detection, and in particular relates to a method for optimizing resonant frequency detection based on the principle of inductive coupling. Background Art

[0002] Inductive coupling refers to the mutual induction, or coupling, between two adjacent inductors due to electromagnetic induction. Because the two inductors can transmit signals without a direct wire connection, enabling wireless energy and information transfer, inductive coupling has been widely used in fields such as wireless charging and sensors.

[0003] In the sensor field, the principle of inductive coupling has been applied to many detection fields, including displacement detection, pressure detection, flow detection, temperature and humidity detection, etc. In these sensors, the resonant frequency of the LC resonant circuit is often detected as an intermediate quantity, thereby mapping the changes in the sensor to be measured.

[0004] Currently, resonant frequency detection mostly uses a swept frequency method. To obtain the resonant frequency, a swept frequency signal must be emitted at regular frequency intervals within the operating frequency range. Compared to instantaneous voltage and current detection, resonant frequency detection requires a longer time to obtain a single data point. Furthermore, the measured value in the sensor is a constantly changing value that can be affected by various factors and can change during a single sweep, affecting the resonant frequency calculation. Furthermore, to maximize the accuracy of the obtained results, the sweep frequency step size must be reduced to improve the accuracy of the resonant frequency. However, when the sweep frequency speed remains constant due to hardware limitations, a smaller sweep frequency step size results in a longer single sweep time, which not only affects data acquisition speed but also can introduce errors in the test results due to fluctuations in the measured value. Furthermore, when the frequency-varying swept frequency signal excites the sensor system, the sensor system responds with a delay, causing the detected response characteristics at a given moment to lag behind the signal generation, resulting in an offset in the calculated resonant frequency. In general, the current method of frequency sweeping to detect resonant frequency has three shortcomings: 1. The delay of a single detection is too long, resulting in changes in the signal to be detected during a frequency sweep, which will affect the measurement of the resonant frequency; 2. There is a contradiction between the frequency sweep step and the frequency sweep time, making it difficult to improve the accuracy of the test results within the limited test time; 3. There is a delay in the sensor system's response to the frequency sweep signal, which causes the calculated resonant frequency to shift. Therefore, in order to address the shortcomings of existing resonant frequency detection, it is very necessary to optimize the resonant frequency detection algorithm. The resonant frequency optimization detection algorithm proposed in this invention has great practical application value. Summary of the Invention

[0005] In view of the shortcomings of the existing method of scanning frequency detection of resonant frequency, the present invention proposes a method for optimizing resonant frequency detection, which solves the problem that the change of the detected signal affects the measurement of resonant frequency.

[0006] A method for optimizing resonant frequency detection of the present invention comprises the following steps:

[0007] Step 1, set the sweep frequency range [F s ,F e ] and sweep frequency step ΔF to perform a forward frequency sweep;

[0008] Step 2: judging whether there is an extreme value of the output intermediate quantity during the frequency sweep according to the change of the intermediate quantity output during the frequency sweep, wherein the intermediate quantity is voltage or current;

[0009] If there is no extreme value, increase the sweep range and sweep step and return to step 1;

[0010] If there is an extreme value, the sweep frequency when the intermediate value reaches the extreme value is output as the resonant frequency point f0;

[0011] Step 3: Perform a reverse frequency sweep with a sweep range of [F e , F s ], the frequency sweep step is ΔF, and it is determined whether there is an output extreme value in this frequency sweep;

[0012] If there is no extreme value, increase the sweep range and sweep step, and perform another reverse sweep;

[0013] If there is an extreme value, the sweep frequency when the intermediate value reaches the extreme value is output as the resonant frequency point f1;

[0014] Step 4: Perform another forward frequency sweep and determine whether there is an output extreme value in this frequency sweep based on the change in the intermediate quantity output during this frequency sweep.

[0015] If there is no extreme value, increase the sweep range and sweep step and perform another forward sweep;

[0016] If there is an extreme value, the sweep frequency when the intermediate value reaches the extreme value is output as the resonant frequency point f2;

[0017] Step 5, calculate the final resonant frequency point:

[0018] f=(f0+f2+2f1) / 4,

[0019] And determine whether it satisfies:

[0020] f2-f0<3ΔF

[0021] If it is not satisfied, it is considered that the resonant frequency error of this calculation is large, the calculation result is discarded and the process returns to step 1;

[0022] If satisfied, the calculation result is considered valid, the calculated value f is output, the sweep frequency range and step frequency are narrowed, and the process returns to step 1.

[0023] Furthermore, the increase in the sweep frequency range and the sweep frequency step is specifically, F s =F s -ΔF es , F e =F e +ΔF es , Beneficial effects:

[0024] 1) By comparing the results of two adjacent same-direction sweeps, the measurement error caused by the fluctuation of the measured value during the sweep is effectively reduced;

[0025] 2) The sweep range and step size are dynamically adjusted based on the test results, ensuring the effective operation of the system while resolving the conflict between the test time and the sweep range and step size.

[0026] 3) Using a frequency sweep scheme that alternates between different directions offsets the system's delay error. Ideally, if the system delay is fixed, the resonant frequency offset is equal in both sweep directions. Therefore, by averaging the resonant frequencies detected in both sweep directions, the system's delay error can be offset. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a timing diagram of the method of the present invention;

[0028] Figure 2 It is an execution flow chart of the invention method of this case. DETAILED DESCRIPTION

[0029] A method for optimizing resonant frequency detection of the present invention is as follows: Figure 2 As shown, the following steps are included:

[0030] Step 1, set the sweep frequency range [F s ,F e ] and sweep frequency step ΔF to perform a forward frequency sweep;

[0031] Step 2: Based on the change of the intermediate quantity output during the frequency sweep, determine whether there is an extreme value of the intermediate quantity output during the frequency sweep. Depending on the detection scenario, the intermediate quantity can be voltage or current. Figure 1 If there is no extreme value, increase the sweep range and sweep step and scan again, for example, F s =F s -ΔFes , F e =F e +ΔF es , Return to step 1;

[0032] If there is an extreme value, the sweep frequency when the intermediate value reaches the extreme value is output as the resonant frequency point f0;

[0033] Step 3: Perform a reverse frequency sweep with a sweep range of [F e , F s ], the frequency sweep step is ΔF, and it is determined whether there is an output extreme value in this frequency sweep.

[0034] If there is no extreme value, increase the sweep range and sweep step, F s =F s -ΔF es , F e =F e +ΔF es , Perform another reverse sweep;

[0035] If there is an extreme value, the sweep frequency when the intermediate value reaches the extreme value is output as the resonant frequency point f1;

[0036] Step 4: Perform another forward frequency sweep and determine whether there is an output extreme value in this frequency sweep based on the change in the intermediate quantity output during this frequency sweep.

[0037] If there is no extreme value, increase the sweep range and sweep step, F s =F s -ΔF es , F e =F e +ΔF es , Perform another forward sweep;

[0038] If there is an extreme value, the sweep frequency when the intermediate value reaches the extreme value is output as the resonant frequency point f2;

[0039] Step 5, calculate the final resonant frequency point:

[0040] f=(f0+f2+2f1) / 4,

[0041] And determine whether it satisfies:

[0042] f2-f0<3ΔF

[0043] If it is not satisfied, it is considered that the resonant frequency error of this calculation is large, the calculation result is discarded and the process returns to step 1;

[0044] If satisfied, the calculation result is considered valid, the calculated value f is output, the sweep frequency range and step frequency are narrowed, and the process returns to step 1.

[0045] In summary, the present invention utilizes the comparison of adjacent same-direction sweep results to effectively reduce data errors caused by fluctuations in the measurement; adopts a method of dynamically adjusting the sweep range according to the current resonant frequency value to effectively resolve the contradiction between the sweep step and the sweep time; and adopts a sweep scheme with alternating directions to offset the system's delay error.

Claims

1. A method for optimizing resonant frequency detection, characterized in that: The steps include: Step 1, set the sweep frequency range [F s ,F e ] and sweep frequency step ΔF to perform a forward frequency sweep; Step 2: Based on the change of the intermediate quantity output during the frequency sweep, determine whether there is an extreme value of the intermediate quantity output during the frequency sweep; If there is no extreme value, increase the sweep range and sweep step and return to step 1; If there is an extreme value, the sweep frequency when the intermediate value reaches the extreme value is output as the resonant frequency point f0; Step 3: Perform a reverse frequency sweep with a sweep range of [F e , F s ], the frequency sweep step is ΔF, and it is determined whether there is an output extreme value in this frequency sweep; If there is no extreme value, increase the sweep range and sweep step, and perform another reverse sweep; If there is an extreme value, the sweep frequency when the intermediate value reaches the extreme value is output as the resonant frequency point f1; Step 4: Perform another forward frequency sweep and determine whether there is an output extreme value in this frequency sweep based on the change in the intermediate quantity output during this frequency sweep. If there is no extreme value, increase the sweep range and sweep step and perform another forward sweep; If there is an extreme value, the sweep frequency when the intermediate value reaches the extreme value is output as the resonant frequency point f2; Step 5, calculate the final resonant frequency point: f=(f0+f2+2f1) / 4, And determine whether it satisfies: f2-f0<3ΔF If it is not satisfied, it is considered that the resonant frequency error of this calculation is large, the calculation result is discarded and the process returns to step 1; If satisfied, the calculation result is considered valid, the calculated value f is output, the sweep frequency range and step frequency are narrowed, and the process returns to step 1.

2. The method for optimizing resonant frequency detection according to claim 1, wherein: The intermediate quantity is voltage or current.

3. The method for optimizing resonant frequency detection according to claim 1, characterized in that: The increase in the sweep frequency range and the sweep frequency step is specifically, F s =F s -ΔF es , F e =F e +ΔF es ,

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