Low-power-consumption traveling wave low-pass filter based on single power supply

Abstract

The utility model discloses a low-power-consumption traveling wave low-pass filter based on a single power supply. The low-power-consumption traveling wave low-pass filter comprises an operational amplifier and the single power supply, an in-phase input end of the operational amplifier is connected with a signal input end after passing through a resistor R9, a resistor R8 and a resistor R6, the in-phase input end and the resistor R9 are grounded through a capacitor C19, the resistors R9 and R8 are connected with an output end of the operational amplifier through a capacitor C18, the resistors R8 and R6 are connected with a power supply after passing through a resistor R7 and a resistor bridge circuit, and the resistor bridge circuit is connected with the power supply. A grounding capacitor C20 and a grounding resistor R10 are respectively connected between the resistor R7 and the resistance bridge circuit; the resistance bridge circuit is further connected with the inverting input end and the output end OUT of the operational amplifier, and the output end OUT is connected with the signal output end. According to the utility model, by using the specially designed single power supply type low-pass filter, the low power consumption characteristic is realized while the filtering performance is ensured, and the low-power consumption low-pass filter can be adapted to products with high requirements on low power consumption, such as a cable monitoring device and a distributed fault monitoring device, and is wide and flexible in application range.

Description

Technical Field

[0001] The utility model belongs to the field of power detection, and particularly relates to a low-power traveling wave low-pass filter based on a single power supply. Background Art

[0002] The power lines of the distribution network and the transmission network are intricate. When in an abnormal state, the waveforms will transmit crosstalk in the cable and are also superimposed with a large number of interference signals. These situations make it very difficult to obtain the waveform data of the actual abnormal state of the power line, making it difficult for technicians to use the high-frequency waveform characteristics that are bound to appear during line faults to diagnose the specific fault location of the line, thus laying a potential fault hazard for the subsequent continuous operation of the power line.

[0003] The main function of the low-pass filter is to allow low-frequency signals to pass through while suppressing signals higher than a specific cut-off frequency. Therefore, in signal processing, the low-pass filter is used to remove noise in the signal or smooth the signal data. Therefore, based on this low-pass filter, the high-frequency interference waveforms generated during power grid operation can be suppressed, providing a basis for subsequent data acquisition, waveform reproduction, fault analysis, and fault location.

[0004] The commonly used Butterworth low-pass filter is the flattest in the passband, without ripples, has a small order, and good real-time performance. However, the transition band is relatively large, and the phase is non-linear, which may cause waveform distortion after filtering. Traditional filters generally use positive and negative dual power supplies to supply power in order to match the input signal and the subsequent circuit. However, due to the BUCK and BOOST circuits with high voltage differences in the power supply scheme, there is naturally a problem of high power consumption, and it has no advantage in products with high low-power requirements. Summary of the Utility Model

[0005] In order to solve the above technical problems, the utility model provides a low-power traveling wave low-pass filter based on a single power supply.

[0006] The technical solution provided by the utility model is as follows:

[0007] A low-power traveling-wave low-pass filter based on a single power supply, comprising an operational amplifier U1, a power supply, and several resistors and capacitors; the non-inverting input terminal IN+ of the operational amplifier U1 is sequentially connected to the signal input terminal through a resistor R9, a resistor R8, and a resistor R6. A capacitor C19 is grounded between the non-inverting input terminal IN+ and the resistor R9. A capacitor C18 is connected between the resistors R9 and R8 and the output terminal of the operational amplifier U1. Between the resistors R8 and R6, it is sequentially connected to the power supply through a resistor R7 and a resistor bridge circuit. A grounded capacitor C20 and a grounded resistor R10 are respectively connected between the resistor R7 and the resistor bridge circuit; the resistor bridge circuit is also respectively connected to the inverting input terminal IN- and the output terminal OUT of the operational amplifier U1. The output terminal OUT is connected to the signal output terminal, and the power supply interface of the operational amplifier U1 is connected to the power supply.

[0008] Further, the resistor bridge circuit is formed by sequentially connecting a resistor R11, a resistor R12, a resistor R13, and a resistor R21 end to end. Between the resistors R11 and R12, it is connected to the inverting input terminal IN- of the operational amplifier U1. Between the resistors R12 and R13, it is connected to the output terminal OUT of the operational amplifier U1. Between the resistors R13 and R21, it is connected to the power supply. Between the resistor R21 and the resistor R11, it is connected to the resistor R7.

[0009] Further, the resistors R11 and R12 are variable resistors for adjusting the gain of the filter.

[0010] Further, the signal input terminal includes a relay J1 connected to the resistor R6 through a DC-blocking capacitor C17.

[0011] Further, the signal output terminal includes a relay J2 connected to the output terminal OUT of the operational amplifier U1 through a DC-blocking capacitor C21.

[0012] Further, a grounded resistor R75 is also connected between the capacitor C21 and the relay J2.

[0013] Advantages of the present utility model:

[0014] Compared with the traditional dual-power supply scheme, by using a specially designed single-power supply type low-pass filter, the present utility model has the characteristics of low power consumption while ensuring the filtering performance. It can be adapted to products with high requirements for low power consumption, such as cable monitoring devices and distributed fault monitoring devices. It can meet the usage requirements after simple power supply, and has a wide application range and flexibility. Description of the Drawings

[0015] The drawings are used to provide a further understanding of the present utility model, and constitute a part of the specification. They are used to explain the present utility model together with the embodiments of the present utility model, and do not constitute a limitation to the present utility model.

[0016] Figure 1 is the circuit schematic diagram provided by an embodiment of the present utility model;

[0017] Figure 2 is the circuit simulation Bode plot provided by an embodiment of the present utility model. Specific embodiments

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0019] This embodiment provides a low-power traveling-wave low-pass filter based on a single power supply, as Figure 1 shown, which mainly consists of an operational amplifier, a power supply, and several resistors and capacitors.

[0020] Specifically, the non-inverting input terminal IN+ of the operational amplifier U1 is sequentially connected to the signal input terminal through resistors R9, R8, and R6. A capacitor C19 is grounded between the non-inverting input terminal IN+ and the resistor R9. A capacitor C18 is connected between the resistors R9 and R8 and the output terminal of the operational amplifier U1. A resistor R7 and a resistor bridge circuit are sequentially connected between the resistors R8 and R6 and then connected to the power supply. A grounded capacitor C20 and a grounded resistor R10 are respectively connected between the resistor R7 and the resistor bridge circuit. The resistor bridge circuit is composed of resistors R11, R12, R13, and R21 connected end to end in sequence. The connection between the resistors R11 and R12 is connected to the inverting input terminal IN- of the operational amplifier U1. The connection between the resistors R12 and R13 is connected to the output terminal OUT of the operational amplifier U1. The connection between the resistors R13 and R21 is connected to the power supply. The connection between the resistors R21 and R11 is connected to the resistor R7. The output terminal OUT of the operational amplifier U1 is connected to the signal output terminal. The power supply interface of the operational amplifier U1 is connected to the power supply. The signal input terminal includes a relay J1 connected to the resistor R6 through a capacitor C17. The signal output terminal includes a relay J2 connected to the output terminal OUT of the operational amplifier U1 through a capacitor C21. A grounded resistor R75 is also connected between the capacitor C21 and the relay J2.

[0021] In this embodiment, a single 5V power supply is adopted. The resistors R21 and R10 are used for voltage division to obtain a bias voltage of 1 / 2×5V. The function of C20 is energy storage and filtering of the bias voltage. Assume that the capacitance values of capacitors C18 and C19 are C (unit: F), and the resistance values of resistors R8 and R9 are R (unit: Ω). To balance the resistances of the two input terminals of the operational amplifier U1 to the ground, it should be ensured that R 11 / / R 12 = 2R. Capacitors C17 and C21 are respectively used as DC blocking capacitors for input and output signals, and their value ranges are ≥100C. The function of the R75 resistor is to output the load, and its value range is between 500Ω and 1000Ω to stabilize the output signal voltage. By adjusting the resistance values of R11 and R12, different gain results can be obtained, but the gain needs to be kept within 3 times to prevent circuit oscillation. When the gain of the circuit is set to 1, R11 and R12 are short-circuited with 0Ω, and the resistance values can be ignored. At this time, R13 is removed.

[0022] Set the cut-off frequency of this low-pass filter to f0 (unit: Hz), then Set the amplification factor to A u , then The quality factor of the circuit is: The application scenario of this embodiment is for filtering power traveling waves with frequencies below 1MHz. The frequency range of the traveling wave is 2K~1MHz. Therefore, the cut-off frequency is limited to 1.129MHz. At this time, the corresponding calculation of the R value is As Figure 2 shown, it is the simulation Bode characteristic diagram of the circuit. When this embodiment circuit is actually used, it is a micro-module, and the installation environment is for PCB board-level installation. The power supply feature of the circuit is single 5V power supply, which is a simpler design compared with the conventional one (the conventional scheme requires ± power supplies and a VREF reference power supply). The most direct manifestation is the reduction of the overall circuit power consumption.

[0023] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; under the idea of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other variations in different aspects of the present invention as described above. For the sake of brevity, they are not provided in detail; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of each embodiment of the present application.

Claims

1. A low-power traveling wave low-pass filter based on a single power supply, characterized in that: It includes an operational amplifier U1, a power supply and a plurality of resistors and capacitors; the in-phase input terminal IN+ of the operational amplifier U1 is connected to the signal input terminal through resistors R9, R8 and R6 in sequence, the in-phase input terminal IN+ and the resistor R9 are grounded through a capacitor C19, the resistors R9 and R8 are connected to the output terminal of the operational amplifier U1 through a capacitor C18, the resistors R8 and R6 are connected to the power supply through resistors R7 and a resistor bridge circuit in sequence, and a grounded capacitor C20 and a grounded resistor R10 are respectively connected between the resistor R7 and the resistor bridge circuit; the resistor bridge circuit is also respectively connected to the inverting input terminal IN- and the output terminal OUT of the operational amplifier U1, the output terminal OUT is connected to the signal output terminal, and the power supply interface of the operational amplifier U1 is connected to the power supply.

2. A low-power traveling wave low-pass filter based on a single power supply as claimed in claim 1, characterized in that: The resistor bridge circuit is formed by connecting resistors R11, R12, R13 and R21 end to end in sequence, wherein resistors R11 and R12 are connected to the inverting input terminal IN- of the operational amplifier U1, resistors R12 and R13 are connected to the output terminal OUT of the operational amplifier U1, resistors R13 and R21 are connected to a power supply, and resistors R21 and R11 are connected to resistor R7.

3. A low-power traveling wave low-pass filter based on a single power supply as claimed in claim 2, characterized in that: The resistor R11 and the resistor R12 are variable resistors for adjusting the filter gain.

4. A low-power traveling wave low-pass filter based on a single power supply as claimed in claim 1, characterized in that: The signal input terminal includes a relay J1 connected to a resistor R6 via a DC blocking capacitor C17.

5. A low-power traveling wave low-pass filter based on a single power supply as claimed in claim 1, characterized in that: The signal output terminal includes a relay J2 connected to the output terminal OUT of the operational amplifier U1 through a DC blocking capacitor C21.

6. A low-power traveling wave low-pass filter based on a single power supply as claimed in claim 5, characterized in that: A grounded resistor R75 is also connected between the capacitor C21 and the relay J2.

Images