CN210269894U - Filter circuit based on weak rotor current signal extraction - Google Patents
Filter circuit based on weak rotor current signal extraction Download PDFInfo
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- CN210269894U CN210269894U CN201920861922.XU CN201920861922U CN210269894U CN 210269894 U CN210269894 U CN 210269894U CN 201920861922 U CN201920861922 U CN 201920861922U CN 210269894 U CN210269894 U CN 210269894U
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Abstract
The utility model discloses a filter circuit based on weak rotor current signal draws uses hierarchical filtering design, splits filter circuit, makes the function target of circuit at different levels more specific more, makes the circuit function at different levels concretize. The characteristics of signals to be processed by each stage of circuits are totally broken up, and the extraction and separation of rotor current signals are facilitated. The primary filter circuit adopts cascade connection of first-order active and passive filters, and the first-order filtering poles are all zero poles, so that the problem interference of poles is avoided, and the stability of the filter circuit is improved due to the combined use of the active filtering and the passive filtering. Because the signal after primary filtering still contains power frequency signal and higher harmonic signal, the amplification factor should not be selected too big, too big amplification factor will make subsequent filtering more difficult, however, too little selection of amplification factor is difficult to play the effect of amplification, adopt gain adjustable inverting amplifier circuit.
Description
Technical Field
The utility model belongs to the technical field of asynchronous machine rotational speed measures, specifically be a filter circuit based on weak rotor current signal draws is related to.
Background
When an induction coil is used for collecting a shaft end leakage magnetic field of the motor, in an induction voltage signal output by the induction coil, the frequency of a stator current signal, namely a power frequency signal, is far higher than that of a rotor current signal, and the signal is weak and is mixed with a large amount of higher harmonic signals. For such weak signal extraction, a signal after simple filtering cannot be used by an envelope detection circuit, and it is difficult to extract a rotor current signal. As for the filter design using the conventional integral butterworth filter design method, the current design scheme is to design using a 3-stage 2-order active low-pass filter, and in the design process, the design is often performed according to the cut-off frequency and the pass-band attenuation according to the inherent design method, and the influence of the problem of the pole of the filter is not fully considered. The pole of the filter is directly related to the stability of the filter, so that the filter is just in normal use but difficult to work for a long time.
In the process of measuring the rotating speed of the asynchronous motor by an induction method, in a shaft end leakage magnetic field of the motor, a rotor current frequency signal is mainly required to be extracted and measured. Since the rotor current frequency signal itself is very weak, the electromotive force generated by the induction coil and related to the rotor current frequency is also very weak. When the subsequent single-chip microcomputer measuring system measures the rotor current frequency signal, certain requirements are placed on the aspects of the waveform, the voltage range, the precision and the like of the rotor current frequency signal. Therefore, the signal output by the induction coil needs to be processed to meet the subsequent measurement requirement. The voltage signal output by the induction coil mainly comprises a rotor frequency signal with the frequency of 0.5-4.5Hz and the power of-50 dBm, a power grid frequency signal with the frequency of 50Hz and the power of-3 dBm and higher harmonics of the power grid frequency signal, the voltage is raised to 6.2V by a voltage stabilizing circuit, the induction signal is in the range of 0-12V, and then the accurate extraction of the 0.5-4.5Hz signal is realized by a filtering and amplifying circuit.
SUMMERY OF THE UTILITY MODEL
In order to solve the above problem, an object of the utility model is to provide a filter circuit based on weak rotor current signal draws.
The purpose of the utility model can be realized by the following technical scheme:
a filter circuit based on weak rotor current signal extraction comprises a first-order passive low-pass filter circuit, a first-order active low-pass filter circuit and a reverse signal amplification circuit which are connected with each other;
the first-order passive low-pass filter circuit comprises a resistor R3, a resistor R4, a capacitor C1 and a capacitor C2, wherein one end of the resistor R3 is connected with the anodes of the resistor R4 and the capacitor C1;
the other end of the resistor R4 is respectively connected with the anode of the capacitor C2 and the resistor R5;
the first-order active low-pass filter circuit comprises an inverting amplifier U1A and an inverting amplifier U1B, wherein an inverting input end of the inverting amplifier U1A is connected with the other end of a resistor R5 and is connected with an output end through a resistor R6 and a capacitor C3 which are connected in parallel, a non-inverting input end is grounded through a resistor R7, and an output end is connected with a resistor R8;
the non-inverting input end of the inverting amplifier U1B is grounded through a resistor R11, the inverting input end is connected with the other end of the resistor R10 and is connected with the output end through a resistor R12 and a capacitor C6 which are connected in parallel, and the output end is connected with a resistor R13;
the inverting amplifying circuit comprises an inverting amplifier U1C, wherein the non-inverting input end of the inverting amplifier U1C is grounded through a resistor R15, the inverting input end is connected with a resistor R14, and the inverting input end is connected with the output end through a resistor R16 and a resistor R22 which are connected in series.
Furthermore, the negative electrode of the capacitor C2 and the negative electrode of the capacitor C1 are both grounded.
Further, the 11 pin of the inverting amplifier U1A is connected to a negative voltage, and the 4 pin is connected to a positive voltage.
Furthermore, the resistors (R8) are respectively connected with the anode of the capacitor C5, the resistor R10 and the cathode of the capacitor C5 are grounded.
Further, the resistor R13 is connected to the resistor R14 and the capacitor C7, respectively.
Further, the resistor R16 is connected to the resistor R18 and the resistor R22, respectively, and the other end of the resistor R18 is grounded.
Further, the models of the inverting amplifier U1A, the inverting amplifier U1B and the inverting amplifier U1C are LM324 AD.
The utility model has the advantages that:
the application discloses filter circuit based on weak rotor current signal draws uses hierarchical filtering design, splits filter circuit apart, and the function target of making each level of circuit function concretize more clearly more at each level of circuit. The characteristics of signals to be processed by each stage of circuits are totally broken up, and the extraction and separation of rotor current signals are facilitated. The primary filter circuit adopts cascade connection of first-order active and passive filters, and the first-order filtering poles are all zero poles, so that the problem interference of poles is avoided, and the stability of the filter circuit is improved due to the combined use of the active filtering and the passive filtering. Because the signal after primary filtering still contains power frequency signal and higher harmonic signal, the amplification factor should not be selected too big, too big amplification factor will make subsequent filtering more difficult, however, too little selection of amplification factor is difficult to play the effect of amplification, adopt gain adjustable inverting amplifier circuit.
Drawings
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Fig. 1 is a schematic circuit diagram of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.
A filter circuit based on weak rotor current signal extraction comprises a first-order passive low-pass filter circuit, a first-order active low-pass filter circuit and a reverse signal amplifying circuit which are connected with each other, as shown in figure 1;
the first-order passive low-pass filter circuit comprises a resistor R3, a resistor R4, a capacitor C1 and a capacitor C2, wherein one end of the resistor R3 is connected with the anodes of the resistor R4 and the capacitor C1;
the circuit is added with an alternating current signal source to simulate signals collected by the induction coil;
specifically, one end of the resistor R3 is connected to the ac signal source V1, the ac signal source V2, and the ac signal source V3, respectively;
specifically, the other ends of the ac signal source V1, the ac signal source V2, and the ac signal source V3 are respectively connected to the resistor R1, the resistor R2, and the resistor R9;
it should be noted that the peak voltages of the ac signal source V1, the ac signal source V2, and the ac signal source V3 are 0.00145Vpk, 0.22Vpk, and 0.0135Vpk, respectively, and the frequencies are 4Hz, 50Hz, and 150Hz, respectively;
specifically, the other ends of the resistor R1, the resistor R2 and the resistor R9 are all grounded;
the other end of the resistor R4 is respectively connected with the anode of the capacitor C2 and the resistor R5;
specifically, the negative electrode of the capacitor C2 and the negative electrode of the capacitor C1 are both grounded;
the first-order active low-pass filter circuit comprises an inverting amplifier U1A and an inverting amplifier U1B, wherein an inverting input end of the inverting amplifier U1A is connected with the other end of a resistor R5 and is connected with an output end through a resistor R6 and a capacitor C3 which are connected in parallel, a non-inverting input end is grounded through a resistor R7, and an output end is connected with a resistor R8;
specifically, the 11 pin of the inverting amplifier U1A is connected with a negative voltage, and the 4 pin is connected with a positive voltage;
the positive voltage is 6V, and the negative voltage is-6V;
it should be noted that, in the process of using Multism simulation, it is difficult to simulate a real magnetic field, so that ac voltage sources with different frequencies and peak values are used in parallel to replace an induction signal input part, which makes the voltage-boosting circuit difficult to simulate, and filtering amplification in subsequent circuits is all directed at processing two ends of an inductor, i.e. an output signal of an induction coil, so that voltage offset is added to the ac voltage sources, and the voltage-boosting circuit cannot be completely simulated, so that ac voltage sources with different frequencies and peak values are finally used in parallel, a dc offset is 0V to simulate the input part of the induction coil, and a power supply part of the circuit uses a bipolar power supply of ± 6V to supply power;
specifically, the resistors R8 are respectively connected with the anode of the capacitor C5 and the resistor R10;
specifically, the negative electrode of the capacitor C5 is grounded;
the non-inverting input end of the inverting amplifier U1B is grounded through a resistor R11, the inverting input end is connected with the other end of the resistor R10 and is connected with the output end through a resistor R12 and a capacitor C6 which are connected in parallel, and the output end is connected with a resistor R13;
specifically, the resistor R13 is respectively connected to the resistor R14 and the capacitor C7, and the other end of the capacitor C7 is grounded;
the inverting amplifying circuit comprises an inverting amplifier U1C, wherein the non-inverting input end of the inverting amplifier U1C is grounded through a resistor R15, the inverting input end is connected with a resistor R14, and is connected with the output end through a resistor R16 and a resistor R22 which are connected in series;
specifically, the resistor R16 is connected to the resistor R18 and the resistor R22, respectively, and the other end of the resistor R18 is grounded;
specifically, the models of the inverting amplifier U1A, the inverting amplifier U1B and the inverting amplifier U1C are LM324 AD;
it should be noted that the resistor R1 is 1K Ω, the resistor R2 is 1K Ω, the resistor R9 is 1K Ω, the resistor R3 is 2K Ω, the resistor R4 is 2K Ω, the resistor R5 is 8.2K Ω, the resistor R6 is 150K Ω, the resistor R7 is 16K Ω, the resistor R8 is 2K Ω, the resistor R10 is 8.2K Ω, the resistor R11 is 15K Ω, the resistor R12 is 150K Ω, the resistor R13 is 5.1K Ω, the resistor R14 is 150K Ω, the resistor R15 is 68K Ω, the resistor R16 is 200K Ω, the resistor R18 is 2K Ω, and the resistor R22 is 75K Ω;
note that the capacitance C1 was 10 μ F, the capacitance C2 was 4.7 μ F, the capacitance C3 was 0.1 μ F, the capacitance C5 was 4.7 μ F, the capacitance C6 was 0.22 μ F, and the capacitance C7 was 1 μ F;
it should be noted that the first-order active low-pass amplifying circuit can compensate the attenuation of the signal after passing through the first-order passive low-pass filtering circuit; the amplifying circuit is used for amplifying the signal to be large enough and processing the signal by a subsequent circuit;
it should be noted that the gain of the inverting amplifier circuit is adjustable, because the signal after primary filtering still contains a power frequency signal and a higher harmonic signal, the amplification factor is not suitable to be selected too much, the subsequent filtering is more difficult due to the too large amplification factor, and the amplification function is difficult due to the too small selection of the amplification factor.
In the description herein, references to the description of "one embodiment," "an example," "a specific example," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is merely exemplary and illustrative of the structure of the invention, and various modifications, additions and substitutions as described in the detailed description may be made by those skilled in the art without departing from the structure or exceeding the scope of the invention as defined in the claims.
Claims (7)
1. A filter circuit based on weak rotor current signal extraction is characterized by comprising a first-order passive low-pass filter circuit, a first-order active low-pass filter circuit and a reverse signal amplifying circuit which are connected with each other;
the first-order passive low-pass filter circuit comprises a resistor R3, a resistor R4, a capacitor C1 and a capacitor C2, wherein one end of the resistor R3 is connected with the anodes of the resistor R4 and the capacitor C1;
the other end of the resistor R4 is respectively connected with the anode of the capacitor C2 and the resistor R5;
the first-order active low-pass filter circuit comprises an inverting amplifier U1A and an inverting amplifier U1B, wherein an inverting input end of the inverting amplifier U1A is connected with the other end of a resistor R5 and is connected with an output end through a resistor R6 and a capacitor C3 which are connected in parallel, a non-inverting input end is grounded through a resistor R7, and an output end is connected with a resistor R8;
the non-inverting input end of the inverting amplifier U1B is grounded through a resistor R11, the inverting input end is connected with the other end of the resistor R10 and is connected with the output end through a resistor R12 and a capacitor C6 which are connected in parallel, and the output end is connected with a resistor R13;
the inverting amplifying circuit comprises an inverting amplifier U1C, wherein the non-inverting input end of the inverting amplifier U1C is grounded through a resistor R15, the inverting input end is connected with a resistor R14, and the inverting input end is connected with the output end through a resistor R16 and a resistor R22 which are connected in series.
2. The filtering circuit based on weak rotor current signal extraction as claimed in claim 1, wherein: and the negative electrode of the capacitor C2 and the negative electrode of the capacitor C1 are both grounded.
3. The filtering circuit based on weak rotor current signal extraction as claimed in claim 1, wherein: the inverting amplifier U1A has its 11 pin connected to a negative voltage and its 4 pin connected to a positive voltage.
4. The filtering circuit based on weak rotor current signal extraction as claimed in claim 1, wherein: the resistor R8 is respectively connected with the anode of the capacitor C5 and the resistor R10, and the cathode of the capacitor C5 is grounded.
5. The filtering circuit based on weak rotor current signal extraction as claimed in claim 1, wherein: the resistor R13 is respectively connected with the resistor R14 and the capacitor C7.
6. The filtering circuit based on weak rotor current signal extraction as claimed in claim 1, wherein: the resistor R16 is respectively connected with the resistor R18 and the resistor R22, and the other end of the resistor R18 is grounded.
7. The filtering circuit based on weak rotor current signal extraction as claimed in claim 1, wherein: the models of the inverting amplifier U1A, the inverting amplifier U1B and the inverting amplifier U1C are LM324 AD.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201920861922.XU CN210269894U (en) | 2019-06-10 | 2019-06-10 | Filter circuit based on weak rotor current signal extraction |
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| CN201920861922.XU CN210269894U (en) | 2019-06-10 | 2019-06-10 | Filter circuit based on weak rotor current signal extraction |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115575694A (en) * | 2022-12-09 | 2023-01-06 | 阳明量子科技(深圳)有限公司 | Constant potential rectifier capable of detecting micro-current signal |
| CN115855130A (en) * | 2022-12-28 | 2023-03-28 | 长春奥普光电技术股份有限公司 | Method for extracting coded signal of grating system |
-
2019
- 2019-06-10 CN CN201920861922.XU patent/CN210269894U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115575694A (en) * | 2022-12-09 | 2023-01-06 | 阳明量子科技(深圳)有限公司 | Constant potential rectifier capable of detecting micro-current signal |
| CN115855130A (en) * | 2022-12-28 | 2023-03-28 | 长春奥普光电技术股份有限公司 | Method for extracting coded signal of grating system |
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Granted publication date: 20200407 Termination date: 20210610 |