Piezoelectric ceramic parallel connection-based conducted interference suppression method and system

Abstract

The invention discloses a conducted interference suppression method and system based on piezoelectric ceramic parallel connection. The method comprises the following steps: providing an impedance expression of a single piezoelectric ceramic; establishing a resonant frequency model of the single piezoelectric ceramic by combining the impedance expression and the piezoelectric parameter equation; on the basis, an impedance expression of the piezoelectric ceramics in a parallel state is deduced, so that a resonant frequency design model of the plurality of piezoelectric ceramics in the parallel state is established; conduction interference suppression based on piezoelectric ceramic parallel connection is realized. According to the invention, a plurality of noise peak values of specific frequencies can be significantly attenuated, so that the efficiency of a passive electromagnetic interference (EMI) filter is significantly improved, and the cost of the whole filtering measure is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and particularly to a method and system for suppressing conducted interference based on parallel connection of piezoelectric ceramics. Background Art

[0002] With the rapid development of modern electronic devices and communication systems, the problem of electromagnetic compatibility (EMC) has become increasingly prominent. In particular, the suppression of conducted interference has become one of the key factors affecting the performance of devices and the stability of systems. Conducted interference refers to the electromagnetic interference (EMI) transmitted between different devices through electrical connection paths such as power lines and signal lines. This interference can not only cause unstable operation of devices but may even lead to system failures or data loss. Therefore, how to effectively suppress conducted interference and improve the anti-interference ability of electronic devices has become a technical problem urgently to be solved in the field of electronic engineering.

[0003] Currently, the suppression of conducted interference mainly relies on methods such as filter technology, shielding technology, grounding technology, and material absorption technology. Filter technology filters out interference signals within a specific frequency range by connecting filter elements such as inductors, capacitors, and resistors in series or in parallel on power lines or signal lines. However, in the case of wideband interference or high-power applications, the volume and cost of filters may be relatively high, and their performance may be affected by component nonlinearity and temperature changes. Shielding technology uses a metal shielding layer to cover sensitive circuits or transmission lines to block the intrusion of external electromagnetic waves and the leakage of internal interference. Although it can reduce EMI to a certain extent, for complex systems or high-frequency applications, the shielding effect may not be ideal, and it will increase the weight and cost of the system. Grounding technology reduces the interference current in the ground loop by optimizing the grounding design of the system, thereby reducing the impact of conducted interference. However, in large or complex systems, the optimization of the grounding layout is often complex and difficult to comprehensively cover all interference sources. Material absorption technology uses electromagnetic absorption materials such as ferrite and magnetic materials to absorb and dissipate interference energy. Although it performs excellently in suppressing high-frequency interference, its effect depends on the material selection and application location, and the cost of high-performance materials is relatively high.

[0004] Piezoelectric ceramics, as a material with piezoelectric effect, can achieve energy conversion between mechanical stress and electric field, and are widely used in fields such as sensors, actuators, and energy harvesting. In recent years, researchers have begun to explore the potential of piezoelectric ceramics in EMI suppression, mainly based on their high dielectric constant, good electromagnetic properties, tunability, and the advantages of integration and miniaturization.

[0005] How to use piezoelectric ceramics to suppress conducted interference is the problem faced currently. Summary of the Invention

[0006] The present invention provides a method and system for suppressing conducted interference based on parallel connection of piezoelectric ceramics, which can significantly attenuate the noise peaks at multiple specific frequencies, thereby significantly improving the efficiency of passive EMI filters and reducing the cost of the overall filtering measures.

[0007] The technical solution of the present invention is as follows: A method for suppressing conducted interference based on parallel connection of piezoelectric ceramics, comprising the following steps:

[0008] Step S1: Propose the impedance expression of a single-piece piezoelectric ceramic;

[0009] Step S2: Combine the impedance expression with the piezoelectric parameter equation to establish the resonance frequency model of a single-piece piezoelectric ceramic;

[0010] Step S3: Based on Step S1, derive the impedance expression in the parallel state of piezoelectric ceramics;

[0011] Step S4: Based on Steps S2 and S3, establish the resonance frequency design model of multiple piezoelectric ceramics in the parallel state, and further realize the suppression of conducted interference in the parallel state of piezoelectric ceramics.

[0012] As a preferred technical solution of the present invention patent: In Step S1, the impedance expression of a single-piece piezoelectric ceramic is:

[0013]

[0014] In the formula, Z represents the impedance of a single-piece piezoelectric ceramic, ω represents the angular frequency, j represents the imaginary number, C 0 represents the static capacitance, C m represents the dynamic capacitance, L m represents the dynamic inductance, R m represents the dynamic resistance.

[0015] As a preferred technical solution of the present invention patent: In Step S2, combine the impedance expression with the piezoelectric parameter equation to establish the resonance frequency model of a single-piece piezoelectric ceramic, so that the resonance frequency can be designed by adjusting the size of the single-piece piezoelectric ceramic according to the established model.

[0016] Among them, the piezoelectric parameter equation is:

[0017]

[0018] In the formula, represents the dielectric constant component under the action of constant stress, k p is the electromechanical coupling coefficient, a is the side length of the piezoelectric ceramic, h is its thickness, σ E is the Poisson's ratio, t is the resonance times, ρ is the density, is the elastic compliance coefficient, Qm is the mechanical quality factor, f r is the resonance frequency of a single piezoelectric ceramic.

[0019] In step S2, the resonance frequency model of a single piezoelectric ceramic is:

[0020]

[0021] The impedance expression in the parallel state of piezoelectric ceramics is:

[0022]

[0023] In the formula, Z m represents the impedance of the parallel piezoelectric ceramics, n represents the number of parallel piezoelectric ceramics, R mn represents the dynamic resistance in the parallel state of piezoelectric ceramics, C mn represents the dynamic capacitance in the parallel state of piezoelectric ceramics, L mn represents the dynamic inductance in the parallel state of piezoelectric ceramics.

[0024] In step S4,

[0025] The resonance frequency design model of multiple piezoelectric ceramics in the parallel state is:

[0026]

[0027] In the formula, f m represents the resonance frequency of the parallel piezoelectric ceramics.

[0028] A conducted interference suppression system based on the parallel connection of piezoelectric ceramics, comprising:

[0029] A single impedance module for presenting the impedance expression of a single piezoelectric ceramic;

[0030] A single resonance frequency module for establishing the resonance frequency model of a single piezoelectric ceramic by combining the impedance expression and the piezoelectric parameter equation;

[0031] A parallel connection module for deriving the impedance expression in the parallel state of piezoelectric ceramics;

[0032] A design module for establishing the resonance frequency design model of multiple piezoelectric ceramics in the parallel state, thereby achieving the suppression of conducted interference in the parallel state of piezoelectric ceramics.

[0033] In the operation of the present invention, by presenting the impedance expression of a single-piece piezoelectric ceramic, combining the impedance expression with the piezoelectric parameter equation, a resonance frequency design model of the single-piece piezoelectric ceramic is established. On this basis, the impedance expression of the piezoelectric ceramic in a parallel state is derived, and then the resonance frequency design model of multiple piezoelectric ceramics in a parallel state is derived, thereby realizing the suppression of conducted interference in the parallel state of the piezoelectric ceramics. This method can significantly attenuate the noise peaks at multiple specific frequencies, thereby significantly improving the efficiency of the passive EMI filter and reducing the cost of the overall filtering measure. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flowchart of a method for suppressing conducted interference based on the parallel connection of piezoelectric ceramics according to an embodiment of the present invention patent;

[0035] Figure 2 is a schematic diagram of the equivalent circuit structure of a single-piece piezoelectric ceramic according to an embodiment of the present invention patent;

[0036] Figure 3 is a schematic diagram of the equivalent circuit structure in the parallel state of piezoelectric ceramics according to an embodiment of the present invention patent;

[0037] Figure 4 is a physical photograph of a piezoelectric ceramic (a = 8 mm, h = 0.5 mm) according to an embodiment of the present invention;

[0038] Figure 5 is a physical photograph of a piezoelectric ceramic (a = 4 mm, h = 0.5 mm) according to an embodiment of the present invention.

[0039] Figure 6 is a schematic diagram of using the parallel connection of piezoelectric ceramics or filter capacitors to suppress conducted interference in a flyback converter according to an embodiment of the present invention;

[0040] Figure 7 is the suppression effect of conducted interference using different filtering measures according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention and should not be used to limit the protection scope of the present invention.

[0042] Refer to Figure 1 , a method for suppressing conducted interference based on the parallel connection of piezoelectric ceramics provided by an embodiment of the present invention performs the following steps S1 - S5, and can realize the resonance frequency design in the parallel state of the piezoelectric ceramics, thereby suppressing the noise peaks at multiple specific frequencies.

[0043] The method includes the following steps:

[0044] Step S1: Present the impedance expression of a single-piece piezoelectric ceramic;

[0045] Referring to Figure 2 the equivalent circuit structure of the single-piece piezoelectric ceramic shown, derive its impedance expression:

[0046]

[0047] In the formula, Z represents the impedance of the single-piece piezoelectric ceramic, ω represents the angular frequency, j represents the imaginary number, C 0 represents the static capacitance, C m represents the dynamic capacitance, L m represents the dynamic inductance, R m represents the dynamic resistance.

[0048] Step S2: Based on the impedance expression of the single-piece piezoelectric ceramic proposed in Step S1 and combined with the piezoelectric parameter equation, establish a resonance frequency model of the single-piece piezoelectric ceramic, so that the resonance frequency can be designed by adjusting the size of the single-piece piezoelectric ceramic according to the established model.

[0049] Among them, the piezoelectric parameter equation is:

[0050]

[0051] In the formula, represents the dielectric constant component under constant stress, k p is the electromechanical coupling coefficient, a is the side length of the piezoelectric ceramic, h is the thickness of the piezoelectric ceramic, σ E is the Poisson's ratio, t is the resonance times, ρ is the density, is the elastic compliance coefficient, Q m is the mechanical quality factor, f r is the resonance frequency of the single-piece piezoelectric ceramic. According to the piezoelectric parameter equation, a resonance frequency model can be established:

[0052]

[0053] Step S3: On this basis, according to the equivalent circuit structure of the piezoelectric ceramics in parallel state (as Figure 3 shown), derive its impedance expression:

[0054]

[0055] In the formula, Z m represents the impedance of the parallel piezoelectric ceramics, n represents the number of parallel piezoelectric ceramics, R mn represents the dynamic resistance of the piezoelectric ceramics in parallel state, C mn represents the dynamic capacitance of the piezoelectric ceramics in parallel state, L mn represents the dynamic inductance of the piezoelectric ceramics in parallel state.

[0056] Step S4: Establish a resonance frequency design model for multiple piezoelectric ceramics in a parallel state to achieve suppression of conducted interference based on the parallel state of piezoelectric ceramics.

[0057] In the field of conducted interference suppression, due to its inherent resonance characteristics, a single piezoelectric ceramic can usually only effectively suppress the noise peak at a specific frequency. This limitation makes it difficult for a single piezoelectric ceramic element to meet the actual application requirements when facing broadband or multi-band interference sources.

[0058] To solve this problem, the present invention realizes the simultaneous suppression of multiple frequency interference peaks through the superposition of multiple resonance points. Combining steps S2 and S3, an expression related to the size of the piezoelectric ceramic can be obtained, thereby establishing a resonance frequency design model for multiple piezoelectric ceramics in parallel:

[0059]

[0060] In the formula, f m represents the resonance frequency of the parallel piezoelectric ceramics.

[0061] In step S4, a resonance frequency design model for multiple piezoelectric ceramics in a parallel state is established. According to this model, by designing the size of multiple piezoelectric ceramics, the noise peaks at multiple specific frequencies can be significantly attenuated, thereby significantly improving the efficiency of the passive EMI filter and reducing the cost of the overall filtering measure.

[0062] In application, the size of the piezoelectric ceramic can be designed according to the target frequency, and the corresponding quantity can be set according to different application requirements.

[0063] A conducted interference suppression system based on the parallel connection of piezoelectric ceramics includes:

[0064] A single impedance module for presenting the impedance expression of a single piezoelectric ceramic;

[0065] A single resonance frequency module for establishing a resonance frequency model of a single piezoelectric ceramic by combining the impedance expression and the piezoelectric parameter equation;

[0066] A parallel module for deriving the impedance expression in the parallel state of piezoelectric ceramics;

[0067] A design module for establishing a resonance frequency design model for multiple piezoelectric ceramics in a parallel state, and further achieving suppression of conducted interference based on the parallel state of piezoelectric ceramics.

[0068] Piezoelectric ceramics have a relatively high dielectric constant and low loss, and can exhibit excellent electromagnetic characteristics under high-frequency electric fields, which helps to effectively filter out high-frequency interference signals. By adjusting the geometric structure and electrode layout of piezoelectric ceramics, the tuning of their electrical characteristics can be achieved to meet the requirements of interference suppression in different frequency ranges. In addition, piezoelectric ceramic elements are small in size and easy to integrate into electronic devices without significantly increasing the volume and weight of the system, meeting the needs of modern miniaturized electronic devices.

[0069] In the operation of the present invention, a wider frequency band and more efficient interference filtering effect are achieved while maintaining the low cost and high reliability of the system. The present invention should be able to make full use of the excellent electromagnetic characteristics of piezoelectric ceramics, and through optimizing the parallel configuration and electrical parameters, achieve efficient suppression of multi-band interference, and have good tunability and integration characteristics to meet the strict requirements of modern electronic devices for electromagnetic compatibility.

[0070] To verify the effectiveness of the proposed method, the present invention takes a flyback converter (switching frequency of 210 kHz) as an example, and designs two piezoelectric ceramics according to the designed model of the resonant frequency of multiple piezoelectric ceramics in parallel state, which can greatly attenuate the noise peaks at its switching frequency and the second harmonic. The sizes are a = 8 mm, h = 0.5 mm (as Figure 4 shown), a = 4 mm, h = 0.5 mm (as Figure 5 shown), and place them at the input of the flyback converter to suppress conducted interference (as Figure 6 shown, where PZT represents piezoelectric ceramics, and C Y represents the filter capacitor). To evaluate the conducted interference suppression performance of the piezoelectric ceramics, the present invention takes the suppression effect of a 2.7 nf filter capacitor as a reference. The results of the two filtering measures are as Figure 7 shown. At the switching frequency, the piezoelectric ceramics suppress 11.4 dB more conducted interference than the filter capacitor, and also suppress 7.8 dB more at the second harmonic. The experimental results show that compared with the traditional filter capacitor, the method proposed by the present invention can greatly suppress the noise peaks at multiple frequencies.

[0071] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above specific embodiments. Without departing from the core idea of the present invention, those of ordinary skill in the art can still make various changes and adjustments within the scope of their professional knowledge.

Claims

1. A method for suppressing conducted interference based on piezoelectric ceramic parallel connection, characterized in that: The following steps are involved: Step S1: Propose an impedance expression of a single piezoelectric ceramic; Step S2: combining the impedance expression with the piezoelectric parameter equation to establish a resonant frequency model of a single piezoelectric ceramic; Step S3: Based on step S1, deriving an impedance expression of the piezoelectric ceramic in a parallel state; Step S4: Based on steps S2 and S3, a resonant frequency design model of multiple piezoelectric ceramics in parallel is established, thereby realizing conduction interference suppression based on the piezoelectric ceramics in parallel.

2. A method for suppressing conducted interference based on piezoelectric ceramic parallel connection according to claim 1, characterized in that: In step S1, the impedance expression of the single-piece piezoelectric ceramic is: Where Z represents the impedance of a single piezoelectric ceramic, ω represents the angular frequency, j represents an imaginary number, C0 represents the static capacitance, and C m Represents dynamic capacitance, L m Represents dynamic inductance, R m Represents dynamic resistance.

3. A method for suppressing conducted interference based on piezoelectric ceramic parallel connection according to claim 2, characterized in that: In step S2, the piezoelectric parameter equation is: In the formula, represents the dielectric constant component under constant stress, k p is the electromechanical coupling coefficient, a is the side length of the piezoelectric ceramic, h is the thickness of the piezoelectric ceramic, σ E is Poisson's ratio, t is the number of resonances, ρ is the density, is the elastic compliance coefficient, Q m is the mechanical quality factor, f r is the resonant frequency of the monolithic piezoelectric ceramic.

4. A method for suppressing conducted interference based on piezoelectric ceramic parallel connection according to claim 3, characterized in that: In step S2, The resonant frequency model of a single piece of piezoelectric ceramic is:

5. The method for suppressing conducted interference based on piezoelectric ceramic parallel connection according to claim 4, characterized in that: In step S3, The impedance expression of piezoelectric ceramics in parallel state is: In the formula, Z m represents the impedance of parallel piezoelectric ceramics, n represents the number of piezoelectric ceramics in parallel, R mn Indicates the dynamic resistance of piezoelectric ceramics in parallel, C mn Indicates the dynamic capacitance of piezoelectric ceramics in parallel, L mn It represents the dynamic inductance of piezoelectric ceramics in parallel.

6. The method for suppressing conducted interference based on parallel connection of piezoelectric ceramics according to claim 5, characterized in that: In step S4, The resonant frequency design model of multiple piezoelectric ceramics in parallel is: In the formula, f m Represents the resonant frequency of parallel piezoelectric ceramics.

7. A conducted interference suppression system based on piezoelectric ceramic parallel connection, characterized in that: include: Single impedance module, used to propose the impedance expression of a single piezoelectric ceramic; Single resonant frequency module, used to combine the impedance expression with the piezoelectric parameter equation to establish the resonant frequency model of a single piezoelectric ceramic; Parallel module, used to derive the impedance expression of piezoelectric ceramics in parallel state; The design module is used to establish a resonant frequency design model of multiple piezoelectric ceramics in parallel, thereby realizing the suppression of conducted interference based on the piezoelectric ceramics in parallel.

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