Frequency measuring circuit

Abstract

The utility model discloses a frequency measuring circuit in the field of frequency signal detection. The frequency measuring circuit comprises a frequency signal processing circuit, an analog signal circuit, a digital display circuit and a single-chip microcomputer, a voltage transformer, an amplitude limiting diode, a filter, an amplifying and shaping circuit and a level conversion circuit are sequentially connected into the frequency signal processing circuit; the single-chip microcomputer is provided with a frequency input end, a digital signal output end and a digital display output end, and the single-chip microcomputer is externally connected with a crystal oscillation circuit. The beneficial effects of the utility model are that frequency signals with a larger amplitude range can be measured through the frequency signal processing circuit, and the sensitivity of measurement is improved; the operation speed of the single-chip microcomputer can be improved through clock signals generated by the crystal oscillation circuit, and an average value is obtained by measuring more frequency signals, so that the measurement precision is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to frequency signal measurement field especially a kind of frequency measurement circuit. BACKGROUND

[0002] Frequency signal is an important parameter of hydroelectric generating set, needs to be measured and displayed by special instrument, provides for operation personnel to be patrolled and observed, judges whether unit state is normal.

[0003] Generally, hydroelectric station adopts machine terminal voltage mutual inductor induced voltage as signal source to measure frequency, signal is easy to obtain, and waveform is relatively smooth and stable, but the signal variation amplitude is relatively large.When unit is at low speed, signal amplitude is low and difficult to detect, when speed rises to certain stage but generator excitation is not put into operation, signal is weak and is easily disturbed, accurate measurement cannot be carried out on signal;And signal voltage suddenly strengthens after being connected to network, needs to be limited in amplitude, shaped and so on, otherwise it can cause damage to measurement circuit.Meanwhile, the frequency signal precision measured by existing instrument is low, cannot satisfy the measurement requirement of hydroelectric generating set frequency signal at present stage. SUMMARY

[0004] The purpose of this section is to outline some aspects of the embodiments of the present application and to briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and in the Abstract and the title of the application in order to avoid obscuring the purpose of this section, the Abstract and the title of the application. Such simplifications or omissions cannot be used to limit the scope of the present application.

[0005] In view of the technical problems existing in the prior art, the present application is proposed.

[0006] The purpose of the present application is to provide a frequency measurement circuit, which aims to solve the problem of small amplitude range of frequency signal measurement and low measurement accuracy.

[0007] To solve the above technical problems, the present application provides the following technical solutions: a frequency signal processing circuit, an analog signal circuit, a digital display circuit and a single-chip microcomputer, the single-chip microcomputer is externally connected with a crystal oscillator circuit;

[0008] The frequency signal processing circuit processes alternating voltage, and the processed alternating signal is connected to the frequency input end through a flip-flop;

[0009] The analog signal circuit is provided with a digital-to-analog chip, and the digital-to-analog chip input end is connected to the digital signal output end.

[0010] The digital display circuit is provided with a control chip, and the control chip input end is connected to the digital display output end.

[0011] As a preferred frequency measurement circuit of the utility model, wherein: the frequency signal processing circuit includes voltage transformer, limiting diode, filter, amplification shaping circuit and level conversion circuit.

[0012] As a preferred frequency measurement circuit of the utility model, wherein: the voltage transformer carries out voltage signal isolation to alternating voltage.

[0013] As a preferred frequency measurement circuit of the utility model, wherein: the limiting diode two are a group, two limiting diodes are connected with negative pole and are in series with voltage transformer.

[0014] As a preferred frequency measurement circuit of the utility model, wherein: the filter is equipped with first operational amplifier, and the alternating voltage received by the voltage transformer is clamped by the limiting diode, and the voltage after clamping passes through the first operational amplifier and enters the negative pole of the amplification shaping circuit.

[0015] As a preferred frequency measurement circuit of the utility model, wherein: the level conversion circuit includes optical coupling and trigger in series with the optical coupling, the output end of the amplification shaping circuit is connected with the optical coupling, the voltage after shaping by the amplification shaping circuit enters the optical coupling, and square wave voltage is output by the processing of trigger.

[0016] As a preferred frequency measurement circuit of the utility model, wherein: the output end of the digital-analog chip is connected with the positive pole of the second operational amplifier, the negative pole of the second operational amplifier is connected with adjustable resistance, and the output end of the second operational amplifier is connected with the base of the triode.

[0017] As a preferred frequency measurement circuit of the utility model, wherein: the digital display circuit includes digital tube circuit and indicating lamp display circuit in parallel, and the input end of the digital display circuit is connected with the digital display output end.

[0018] As a preferred frequency measurement circuit of the utility model, wherein: the digital tube circuit is equipped with control chip, and the output end of the control chip is connected with several digital tubes.

[0019] As a preferred frequency measurement circuit of the utility model, wherein: the indicating lamp display circuit is equipped with connecting head, the key interface is connected in the connecting head, the key joint is connected to the single-chip microcomputer, and the output end of the connecting head is connected with several indicating lamps.

[0020] The frequency signal processing circuit can measure the frequency signal with a larger amplitude range, and the sensitivity of measurement is improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor on the basis of these drawings. Among them:

[0022] Figure 1 The frequency measurement circuit single-chip microcomputer structure diagram of an embodiment provided by the present application;

[0023] Figure 2 The frequency signal processing circuit structure diagram of an embodiment provided by the present application;

[0024] Figure 3 The analog signal circuit structure diagram of an embodiment provided by the present application;

[0025] Figure 4 The digital display circuit structure diagram of an embodiment provided by the present application. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings of the specification.

[0027] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.

[0028] Secondly, the present application is described in detail in combination with the schematic diagram, in order to facilitate the description, the sectional view of the device structure will be partially enlarged without the general proportion, and the schematic diagram is only an example, which should not limit the scope of protection of the present application here. In addition, the three-dimensional spatial dimensions of length, width and depth should be included in actual manufacture.

[0029] Embodiment 1

[0030] Refer toFigures 1-4 The embodiment provides a frequency measurement circuit, which comprises a frequency signal processing circuit 100, a limiting diode 102 in the frequency signal processing circuit 100 performs bidirectional clamping processing on an alternating voltage, and the processed alternating signal is connected to a frequency input end 401 of a single-chip microcomputer 400 through a flip-flop 105b; an analog signal circuit 200, which comprises a digital-analog chip 201, an input end of the digital-analog chip 201 is connected to a digital signal output end 402 of the single-chip microcomputer 400; and a digital display circuit 300, which comprises a control chip 301a, an input end of the control chip 301a is connected to a digital display output end 403 of the single-chip microcomputer 400.

[0031] Specifically, the frequency signal processing circuit 100 is used for collecting an induced voltage signal and performing multiple processing on the induced voltage signal, so that the induced voltage signal becomes a square wave signal capable of being received by the single-chip microcomputer 400; the analog signal circuit 200 converts a digital signal transmitted by the single-chip microcomputer 400 into an analog voltage signal of 0-5V, and finally outputs a current signal of 0-20mA; the digital display circuit 300 transmits a signal output by the single-chip microcomputer 400 to a digital tube, and displays the signal in a digital display mode; the single-chip microcomputer 400 serves as a hub of the whole measurement circuit and a transfer station of the voltage signal processing, and can receive a square wave signal output by the frequency signal processing circuit 100 and a key signal, and transmit the processed signals to the next-stage digital-analog signal circuit 200 and the digital display circuit 300 respectively.

[0032] It should be noted that the model of the flip-flop 105b in the frequency signal processing circuit 100 is 74HC74, the model of the digital-analog chip 201 in the analog signal circuit 200 is TLC5620, the model of the control chip 301a in the digital display circuit 300 is PS7219, and the model of the single-chip microcomputer 400 is 78E58.

[0033] Further, the single-chip microcomputer 400 has multiple interfaces, in addition to a frequency input end 401, a signal output end 402 and a digital display output end 403 used for signal transmission, the single-chip microcomputer 400 is further provided with an interface for connecting a crystal oscillation circuit and an interface for connecting a data storage circuit, wherein the speed of processing signals by the single-chip microcomputer 400 is controlled through a clock signal, and the crystal oscillation circuit can provide the single-chip microcomputer 400 with clock signals of different frequencies, so as to control the running speed of the single-chip microcomputer 400.

[0034] When the frequency measurement circuit is used for measurement, the voltage signal is first isolated by the frequency signal processing circuit 100, and then the voltage signal is filtered, amplified and shaped by the limiting diode 102 and other devices, and finally the voltage signal obtained by the frequency signal processing circuit 100 is converted into a square wave signal and transmitted to the single-chip microcomputer 400, which converts the square wave signal into a digital signal after calculation and further processing; the digital signal processed by the single-chip microcomputer 400 is output to the analog signal circuit 200, and finally the digital signal is converted into a current signal that can be received by an external system, and the entire measurement circuit is remotely monitored by an external monitoring system to ensure normal operation of the measurement circuit.

[0035] The instrument is the carrier of the frequency measurement circuit, and a plurality of keys are arranged on the control panel of the instrument, and the key signals generated by pressing the keys can be directly transmitted to the single-chip microcomputer 400, so as to adjust the running speed of the single-chip microcomputer 400, and the indicator lamp and the display screen on the instrument control panel are controlled by the digital display circuit 300.

[0036] By arranging the frequency measurement circuit, the amplitude range of the measurement signal can be greatly improved, and the measurement accuracy is higher under the condition that the sampling frequency is the same, so that the accuracy of the measurement data is greatly improved, and the work efficiency of detection is improved.

[0037] Embodiment 2

[0038] Reference Figures 2-3 For the second embodiment of the utility model, the embodiment is based on the previous embodiment, and the difference between the embodiment and the previous embodiment is that: the frequency signal processing circuit 100 includes a voltage transformer 101, a limiting diode 102, a filter 103, an amplification shaping circuit 104 and a level conversion circuit 105; the voltage transformer 101 performs voltage signal isolation on the alternating voltage; the two limiting diodes 102 are connected in series, and the negative poles of the two limiting diodes 102 are connected to the voltage transformer 101; the filter 103 is provided with a first operational amplifier 103a, the alternating voltage received by the voltage transformer 101 is clamped by the limiting diode 102, the clamped voltage passes through the first operational amplifier 103a and enters the negative pole of the amplification shaping circuit 104; the level conversion circuit 105 includes an optocoupler 105a and a flip-flop 105b connected in series with the optocoupler 105a, the output end of the amplification shaping circuit 104 is connected to the optocoupler 105a, the voltage shaped by the amplification shaping circuit 104 enters the optocoupler 105a and outputs a square wave voltage through the processing of the flip-flop 105b; the output end of the digital-analog chip 201 is connected to the positive pole of the second operational amplifier 202, the negative pole of the second operational amplifier 202 is connected to the adjustable resistor 203, and the output end of the second operational amplifier 202 is connected to the base of the triode 204.

[0039] Specifically, the voltage transformer 101 can transform the high voltage at the water turbine end into low voltage, which not only ensures the safety of the meter and the measurement circuit, but also isolates the high voltage from the staff, thereby improving the safety.

[0040] Preferably, the two limiting diodes 102 are of the same structure, and when the input voltage is too high, the limiting diodes 102 are forward biased to divert the excess voltage and reduce the amplitude of the output signal; when the input voltage is too low, the limiting diodes 102 are reverse blocked to block the input voltage. Through the two limiting diodes 102 arranged oppositely, the AC voltage signal collected by the voltage transformer 101 can be bidirectionally limited in amplitude, thereby ensuring the stability of the collected voltage signal.

[0041] Further, the model of the first operational amplifier 103a in the filter 103 is MC1558, and through the resistance and capacitance arranged in the filter 103, a two-order low-pass active filter is formed, which can filter high-frequency signals.

[0042] It should be noted that the model of the optocoupler 105a is TLP521, which can not only convert the level but also achieve electrical isolation to avoid damage to the circuit. Moreover, the input and output ends of the optocoupler 105a are coupled through optical signals, which can effectively suppress electromagnetic interference and radio frequency interference, thereby improving the stability and reliability of the signal.

[0043] Specifically, the second operational amplifier 202 is of the model M1558. In the analog signal circuit 200, the digital-to-analog chip 201 converts the digital signal output by the single-chip microcomputer 400 into an analog voltage signal in the range of 0-5V, and then the analog voltage signal is converted into a current signal in the range of 0-20mA through the processing of the triode 204 of the model 8050. The finally output current signal can be received by the monitoring system connected outside the meter, thereby realizing real-time monitoring of the frequency measurement circuit in the meter, avoiding the deviation of the measurement data caused by the damage of the measurement circuit, and causing the delay of the maintenance. It is worth mentioning that by adjusting the resistance value of the adjustable resistor 203, the analog signal circuit 200 can be matched with different loads, thereby improving the application range of the analog signal circuit 200.

[0044] Embodiment 3

[0045] Reference Figure 4For the third embodiment of the utility model, the embodiment provides a pipe bending machine, the embodiment is based on the last embodiment, and is different from the last embodiment, that is: the digital display circuit 300 includes the nixie tube circuit 301 and the indicator light display circuit 302 in parallel, the input end of the digital display circuit 300 is connected with the digital display output end 403; the nixie tube circuit 301 is equipped with the control chip 301a, the output end of the control chip 301a is connected with a plurality of nixie tubes 301b; the indicator light display circuit 302 is equipped with the connecting head 302a, the connecting head 302a is connected with the key interface 302b, the key interface 302b is connected to the single-chip microcomputer 400, and the output end of the connecting head 302a is connected with a plurality of indicator lights 302c.

[0046] Specifically, in addition to being capable of outputting digital signals to the analog signal circuit 200, the single-chip microcomputer 400 also transmits signals to the digital display circuit 300, the transmitted signals are converted into control signals after being processed by the control chip 301a, and the control chip 301a can control each nixie tube 301b, so the control chip 301a can be used as a switch of each nixie tube 301b, and it should be noted that the nixie tube 301b is arranged on the instrument display panel.

[0047] Preferably, the signals transmitted by the single-chip microcomputer 400 are also transmitted to the indicator light display circuit 302, and the signals are converted into control signals for controlling the switches of the indicator lights 302c after being input into the connecting head 302a, and it should be noted that the indicator lights 302c are arranged on the display panel of the instrument.

[0048] In summary, the digital display circuit 300 can display the model output by the single-chip microcomputer 400 on the instrument display panel, and the measured data can be observed by the staff in real time, and since the frequency measurement circuit has higher accuracy, more digits can be displayed on the display panel, and the reflected measured data is more accurate.

[0049] It is important to note that the construction and arrangements of the application shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications can be made to the embodiments without departing from the novel teachings and advantages of the subject matter described herein. For example, elements described as integrated in a single unit can be separated, elements described as separate can be integrated, and the position, number, shape, and arrangements of elements can be varied. Accordingly, all such modifications are intended to be included within the scope of the present inventive subject matter. The order or sequence of any process or method steps can be varied or re-sequenced without departing from the general nature of the claims. Any "means plus function" clauses are intended to cover the structures described herein as performing the recited functionality and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes, and omissions can be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the present inventive subject matter. Accordingly, the present inventive subject matter is not limited to the particular embodiments described and illustrated herein, but extends to equivalents of which the foregoing describes are intended to cover.

[0050] Furthermore, in order to provide a concise description of the exemplary embodiments, not all features of an actual implementation can be described (i.e., those pertaining to the

[0051] It is understood that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions can be made. Such development efforts can inevitably lead to a number of substitutions, modifications, changes, and omissions of parts illustrated as having a specific configuration. Such are the natural consequences of research and development efforts, and

[0052] It should be noted that the above examples are intended to illustrate the technical solutions of the present application but not limit the present application, and although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the present application, and all should be included in the scope of the claims of the present application.

Claims

1. A frequency measurement circuit, characterized in that: include, A frequency signal processing circuit (100) includes a limiting diode (102), wherein the limiting diode (102) performs bidirectional clamping processing on an AC voltage, and the processed AC signal is connected to a frequency input terminal (401) of a single-chip microcomputer (400) via a trigger (105b); An analog signal circuit (200) comprises a digital-analog chip (201), wherein an input end of the digital-analog chip (201) is connected to a digital signal output end (402) of the single-chip microcomputer (400); The digital display circuit (300) comprises a control chip (301a), wherein the input end of the control chip (301a) is connected to the digital display output end (403) of the single-chip microcomputer (400).

2. The frequency measurement circuit according to claim 1, wherein: The frequency signal processing circuit (100) comprises a voltage transformer (101), a limiting diode (102), a filter (103), an amplifying and shaping circuit (104), and a level conversion circuit (105).

3. The frequency measurement circuit according to claim 2, wherein: The voltage transformer (101) performs voltage signal isolation on the AC voltage.

4. The frequency measurement circuit according to claim 3, wherein: The two limiting diodes (102) form a group, and the two limiting diodes (102) have their cathodes connected and are connected in series with the voltage transformer (101).

5. The frequency measurement circuit according to claim 4, wherein: A first operational amplifier (103a) is provided in the filter (103), and the AC voltage received by the voltage transformer (101) is clamped by the limiting diode (102). The clamped voltage passes through the first operational amplifier (103a) and enters the negative electrode of the amplifying and shaping circuit (104).

6. The frequency measurement circuit according to claim 5, wherein: The level conversion circuit (105) comprises an optical coupler (105a) and a trigger (105b) connected in series with the optical coupler (105a); the output end of the amplifying and shaping circuit (104) is connected to the optical coupler (105a); the voltage shaped by the amplifying and shaping circuit (104) enters the optical coupler (105a) and is processed by the trigger (105b) to output a square wave voltage.

7. The frequency measurement circuit according to claim 6, wherein: The output end of the digital-analog chip (201) is connected to the positive electrode of the second operational amplifier (202), the negative electrode of the second operational amplifier (202) is connected to the adjustable resistor (203), and the output end of the second operational amplifier (202) is connected to the base of the transistor (204).

8. The frequency measurement circuit according to claim 7, wherein: The digital display circuit (300) comprises a digital tube circuit (301) and an indicator light display circuit (302) connected in parallel, and an input end of the digital display circuit (300) is connected to the digital display output end (403).

9. The frequency measurement circuit according to claim 8, wherein: A control chip (301a) is provided in the digital tube circuit (301), and an output end of the control chip (301a) is connected to a plurality of digital tubes (301b).

10. The frequency measurement circuit according to claim 9, wherein: The indicator light display circuit (302) is provided with a connector (302a), the connector (302a) is connected to a key interface (302b), the key interface (302b) is connected to the single-chip microcomputer (400), and the output end of the connector (302a) is connected to a plurality of indicator lights (302c).

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