A passive filter circuit

Abstract

The utility model relates to a kind of passive filter circuit, the utility model provides a kind of passive filter circuit, including first capacitor C1, second capacitor C2, first inductor L1 and second inductor L2, one end of the first inductor L1 as first input, the other end of the first inductor L1 and one end of the first capacitor C1 are connected in parallel after as first output;One end of the second inductor L2 as second input, the other end of the second inductor L2 and one end of the second capacitor C2 are connected in parallel after as second output;The other end of the first capacitor C1 is also connected together with the other end of the second capacitor C2 first parallel connection before grounding again.The technical scheme provided by the utility model makes common-mode interference signal import ground, improves the filtering effect, and the first capacitor C1, second capacitor C2 capacitance is smaller, widens the through frequency band range, expands the application range of filter circuit.

Description

Technical Field

[0001] This utility model belongs to the field of electromagnetic compatibility technology, and in particular relates to a passive filter circuit. Background Technology

[0002] From an electromagnetic compatibility (EMC) perspective, high-voltage, high-current power supply systems generate a massive instantaneous surge of energy upon startup, causing electromagnetic interference and affecting the normal operation of surrounding electrical components. Generally, the smaller the size of an electrical component, the more susceptible it is to electromagnetic interference. For example, electronic switches and sensors are highly vulnerable to EMC, which can disrupt their normal operation, causing them to release incorrect electrical signals and consequently affecting the reliability of the entire electronic system. Therefore, appropriate filtering circuits are often configured at the input terminals of these components. Common filtering circuits include active and passive filtering circuits. For smaller components like electronic switches and sensors, passive filtering circuits are typically used.

[0003] In the prior art, patent document with publication number "CN207884490U" discloses a high-voltage, high-current DC passive filter circuit, including an input protection circuit, a common-mode passive filter circuit, a differential-mode passive filter circuit, and an output protection circuit. The input protection circuit, common-mode passive filter circuit, differential-mode passive filter circuit, and output protection circuit are connected sequentially. The common-mode passive filter circuit includes a common-mode inductor L1. The input side of the common-mode inductor L1 is connected to capacitors C21 and C22 connected in series. Capacitor C23 is then connected between capacitors C21 and C22, and capacitor C23 is grounded. The output side of the common-mode inductor L1 is connected to capacitors C24 and C25 connected in series. Capacitor C24 and C25 are then connected between capacitors C24 and C25, and capacitor C26 is grounded. This patented technical solution effectively suppresses conducted electromagnetic interference in high-voltage, high-current power supply systems and ensures the safe use of the high-voltage, high-current filter.

[0004] However, existing passive filter circuits mainly include low-pass filter circuits, high-pass filter circuits, and band-pass filter circuits. Among them, the band-pass filter circuit can be regarded as the result of a low-pass filter circuit and a high-pass filter circuit connected in series. The low-pass filter circuit is further divided into RC low-pass filter circuit, LR low-pass filter circuit, and LC low-pass filter circuit. The high-pass filter circuit is further divided into CR high-pass filter circuit, RL high-pass filter circuit, and CL high-pass filter circuit. For filter circuits, the frequency range they pass through is usually inversely proportional to the inductance value of the inductor, the capacitance value of the capacitor, and the resistance value. For RC low-pass filter circuits and LC low-pass filter circuits, increasing the capacitance value is beneficial to improving the noise filtering effect, but it will also narrow the frequency range of the effective signal in the filter circuit, affecting the applicable range of the filter circuit. Utility Model Content

[0005] To solve the above-mentioned technical problems, this utility model provides a passive filter circuit.

[0006] This utility model provides a passive filter circuit, including a first capacitor C1, a second capacitor C2, a first inductor L1 and a second inductor L2. One end of the first inductor L1 serves as a first input terminal (1), and the other end of the first inductor L1 is connected in parallel with one end of the first capacitor C1 to serve as a first output terminal (2). One end of the second inductor L2 serves as a second input terminal (3), and the other end of the second inductor L2 is connected in parallel with one end of the second capacitor C2 to serve as a second output terminal (4). The other end of the first capacitor C1 is also connected in parallel with the other end of the second capacitor C2 before being grounded.

[0007] The capacitance of the first capacitor C1 is equal to the capacitance of the second capacitor C2.

[0008] The capacitance of the first capacitor C1 or the second capacitor C2 is between 1 μF and 40 μF.

[0009] The inductance value of the first inductor L1 is equal to the inductance value of the second inductor L2.

[0010] The inductance value of the first inductor L1 or the inductance value of the second inductor L2 is 1mH to 10mH.

[0011] The passive filter circuit also includes a third capacitor C3, which is bridged between the first input terminal (1) and the second input terminal (3).

[0012] The passive filter circuit also includes a fourth capacitor C4, which is bridged between the first input terminal (1) and the second input terminal (3).

[0013] The passive filter circuit also includes a third inductor L3. One end of the third inductor L3 is connected in parallel with one end of the fifth capacitor C5 to serve as the third input terminal (5). The other end of the third inductor L3 is connected in parallel with one end of the sixth capacitor C6 to serve as the third output terminal (6). The other end of the fifth capacitor C5 is also connected in parallel with the other end of the sixth capacitor C6 before being grounded. The inductance value of the third inductor L3 is equal to the inductance value of the first inductor L1.

[0014] The inductance value of the third inductor L3 is 1mH to 10mH.

[0015] The capacitance of the fifth capacitor C5 is from 1 μF to 80 μF, and the capacitance of the sixth capacitor C6 is from 1 nF to 50 nF.

[0016] The beneficial effects of this utility model are as follows: Using the technical solution provided by this utility model, the first inductor L1 and the second inductor L2 are used to suppress common-mode interference signals and filter out high-frequency noise in the power supply network. Since the other end of the first capacitor C1 is connected in parallel with the other end of the second capacitor C2 before being grounded, a low-impedance grounding path is provided for the common-mode interference signal, allowing the common-mode interference signal to be guided to the ground wire, completely filtering out the common-mode interference signal and improving the circuit filtering effect. Furthermore, after the first capacitor C1 and the second capacitor C2 are grounded, they can also filter out bypass high-frequency noise and avoid circuit self-oscillation. In addition, by selecting the first capacitor C1 and the second capacitor C2 with smaller capacitance values, the effective signal passing frequency range in the filtering circuit can be increased while ensuring the stability of the circuit's noise and ripple filtering effect, thus expanding the applicable range of the filtering circuit. Attached Figure Description

[0017] Figure 1 This is the circuit diagram of this utility model.

[0018] In the diagram: 1-First input terminal, 2-First output terminal, 3-Second input terminal, 4-Second output terminal, 5-Third input terminal, 6-Third output terminal. Detailed Implementation

[0019] The technical solution of this utility model will be further described below with reference to the accompanying drawings, but the scope of protection claimed is not limited to the description. This utility model provides a passive filter circuit, such as Figure 1 As shown, the system includes a first capacitor C1, a second capacitor C2, a first inductor L1, and a second inductor L2. One end of the first inductor L1 serves as the first input terminal 1, and the other end of the first inductor L1 is connected in parallel with one end of the first capacitor C1 to serve as the first output terminal 2. One end of the second inductor L2 serves as the second input terminal 3, and the other end of the second inductor L2 is connected in parallel with one end of the second capacitor C2 to serve as the second output terminal 4. The other end of the first capacitor C1 is also connected in parallel with the other end of the second capacitor C2 before being grounded.

[0020] Using the technical solution provided by this utility model, the first inductor L1 and the second inductor L2 are used to suppress common-mode interference signals and filter out high-frequency noise in the power supply network. Since the other end of the first capacitor C1 is connected in parallel with the other end of the second capacitor C2 before being grounded, a low-impedance grounding path is provided for the common-mode interference signal, allowing the common-mode interference signal to be guided to the ground wire, thus completely filtering out the common-mode interference signal and improving the filtering effect of the circuit. After the first capacitor C1 and the second capacitor C2 are grounded, they can also filter out bypass high-frequency noise and avoid circuit self-oscillation. In addition, the first capacitor C1 and the second capacitor C2 with smaller capacitance values ​​can be selected, which can improve the pass frequency range of the effective signal in the filtering circuit while ensuring the stability of the circuit in filtering noise and ripple, thus expanding the applicable range of the filtering circuit.

[0021] Specifically, the capacitance of the first capacitor C1 is equal to that of the second capacitor C2. The capacitance of either the first capacitor C1 or the second capacitor C2 is between 1 μF and 40 μF. The inductance of the first inductor L1 is equal to that of the second inductor L2. Preferably, the inductance of either the first inductor L1 or the second inductor L2 is between 1 mH and 10 mH. It can be seen that in the technical solution provided by this utility model, the capacitance values ​​of the first capacitor C1, the second capacitor C2, the first inductor L1, and the second inductor L2 are all relatively small. Since the pass frequency range of the filter circuit is inversely proportional to the product of the characteristic parameters of the capacitors and inductors, the filter circuit provided by this utility model has a wider pass frequency range, which is beneficial for expanding the applicability of the filter circuit.

[0022] In addition, the passive filter circuit also includes a third capacitor C3, which is bridged between the first input terminal 1 and the second input terminal 3. Preferably, the capacitance of the third capacitor C3 is between 1μF and 100μF. The passive filter circuit also includes a fourth capacitor C4, which is bridged between the first input terminal 1 and the second input terminal 3. Preferably, the capacitance of the fourth capacitor C4 is between 1nF and 30nF. Using the technical solution of this utility model, both the third capacitor C3 and the fourth capacitor C4 are bridged between the first input terminal 1 and the second input terminal 3. The third capacitor C3 and the fourth capacitor C4 are used to suppress differential-mode interference signals and improve circuit stability. The smaller capacitance of the third capacitor C3 also suppresses high-frequency noise in the circuit and reduces leakage current. The larger capacitance of the fourth capacitor C4 is used to filter out low-frequency interference signals and enhance the filtering effect.

[0023] In addition, the passive filter circuit also includes a third inductor L3. One end of the third inductor L3 is connected in parallel with one end of the fifth capacitor C5 to serve as the third input terminal 5. The other end of the third inductor L3 is connected in parallel with one end of the sixth capacitor C6 to serve as the third output terminal 6. The other end of the fifth capacitor C5 is also connected in parallel with the other end of the sixth capacitor C6 before being grounded. The inductance value of the third inductor L3 is equal to the inductance value of the first inductor L1. Preferably, the inductance value of the third inductor L3 is 1mH to 10mH. The third inductor L3 is a ferrite inductor. The capacitance value of the fifth capacitor C5 is 1μF to 80μF, and the capacitance value of the sixth capacitor C6 is 1nF to 50nF. The first output terminal 2, the second output terminal 4, and the third output terminal 6 are respectively used to connect to the input terminals of the sensor.

Claims

1. A passive filter circuit, characterized in that: It includes a first capacitor C1, a second capacitor C2, a first inductor L1 and a second inductor L2. One end of the first inductor L1 serves as the first input terminal (1), and the other end of the first inductor L1 is connected in parallel with one end of the first capacitor C1 to serve as the first output terminal (2). One end of the second inductor L2 serves as the second input terminal (3), and the other end of the second inductor L2 is connected in parallel with one end of the second capacitor C2 to serve as the second output terminal (4). The other end of the first capacitor C1 is also connected in parallel with the other end of the second capacitor C2 before being grounded.

2. The passive filter circuit as described in claim 1, characterized in that: The capacitance of the first capacitor C1 is equal to the capacitance of the second capacitor C2.

3. The passive filter circuit as described in claim 2, characterized in that: The capacitance of the first capacitor C1 or the second capacitor C2 is between 1 μF and 40 μF.

4. The passive filter circuit as described in claim 1, characterized in that: The inductance value of the first inductor L1 is equal to the inductance value of the second inductor L2.

5. A passive filter circuit as described in claim 4, characterized in that: The inductance value of the first inductor L1 or the inductance value of the second inductor L2 is 1mH to 10mH.

6. A passive filter circuit as described in claim 1, characterized in that: The passive filter circuit also includes a third capacitor C3, which is bridged between the first input terminal (1) and the second input terminal (3).

7. A passive filter circuit as described in claim 1, characterized in that: The passive filter circuit also includes a fourth capacitor C4, which is bridged between the first input terminal (1) and the second input terminal (3).

8. A passive filter circuit as described in claim 1, characterized in that: The passive filter circuit also includes a third inductor L3. One end of the third inductor L3 is connected in parallel with one end of the fifth capacitor C5 to serve as the third input terminal (5). The other end of the third inductor L3 is connected in parallel with one end of the sixth capacitor C6 to serve as the third output terminal (6). The other end of the fifth capacitor C5 is also connected in parallel with the other end of the sixth capacitor C6 before being grounded. The inductance value of the third inductor L3 is equal to the inductance value of the first inductor L1.

9. A passive filter circuit as described in claim 8, characterized in that: The inductance value of the third inductor L3 is 1mH to 10mH.

10. A passive filter circuit as described in claim 8, characterized in that: The capacitance of the fifth capacitor C5 is from 1 μF to 80 μF, and the capacitance of the sixth capacitor C6 is from 1 nF to 50 nF.

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