Circuit for harmonic detection

Abstract

The utility model discloses a circuit for harmonic detection. The circuit comprises a detected access module, a signal acquisition module, a master control module, an oscillation module and a reference capacitor module, the tested access module is used for generating a sampling signal, and the output end of the tested access module is connected with the input end of the signal acquisition module; the output end of the signal acquisition module is connected with the function end of the main control module; the synchronization end of the main control module is connected with the oscillation module; the reference end of the main control module is connected with the reference capacitor module; the output end of the main control module is used for connecting display equipment. The signal acquisition module processes a sampling signal to eliminate a common-mode signal in the sampling signal, and provides a precise clock signal and a reference voltage for the main control module through the oscillation module and the reference capacitor module, so that the main control module can operate accurately. And the collected signals are converted into digital signals which can be identified by the main control module, so that contained harmonic components are calculated to eliminate interference signals, and the system can be applied to more scenes.

Description

TECHNICAL FIELD

[0001] The utility model relates to circuit detection technical field, especially a kind of circuit for harmonic detection. BACKGROUND

[0002] When the existing power distribution line is detected in the scene where power distribution line and other lines are arranged densely, there is a problem that the detection result of the measured line is inaccurate due to electromagnetic interference (EMI, Electromagnetic Interference).

[0003] In order to solve the adverse effects that may be suffered during harmonic detection, a band-pass filter is usually needed to be used to pass only signals within a specific frequency range to reduce interference. However, when using a band-pass filter, there are still interference signals within a specific range, and the effect of excluding interference is insufficient. Moreover, the band-pass filter is applicable to too few scenes and can only be used in specific frequency cases, so the applicability is poor. UTILITY MODEL CONTENT

[0004] The technical problem to be solved by the utility model is to provide a circuit for harmonic detection, which can effectively exclude interference signals in different scenes.

[0005] In order to solve the above technical problem, the utility model adopts the technical scheme of:

[0006] A circuit for harmonic detection includes a measured access module, a signal acquisition module, a main control module, an oscillation module and a reference capacitor module. The measured access module is used to generate a sampling signal, and the output end of the measured access module is connected with the input end of the signal acquisition module. The output end of the signal acquisition module is connected with the function end of the main control module. The synchronous end of the main control module is connected with the oscillation module. The reference end of the main control module is connected with the reference capacitor module. The output end of the main control module is used to connect a display device.

[0007] Further, the measured access module includes a single-chip microcomputer, a drive chip, a first MOS tube, a second MOS tube and a test resistor. The output end of the single-chip microcomputer is connected with the input end of the drive chip. The source of the first MOS tube is used to be connected with a power supply, and the drain of the first MOS tube is connected with the source of the second MOS tube. The drain of the second MOS tube is connected with one end of the test resistor. The output end of the drive chip is respectively connected with the gate of the first MOS tube and the gate of the second MOS tube. The other end of the test resistor is grounded, and the two ends of the test resistor are used as the output end of the measured access module.

[0008] Further, the signal acquisition module comprises an amplifier unit and an adjusting resistor; a positive input end of the amplifier unit is connected with one end of the test resistor; a negative input end of the amplifier unit is connected with the other end of the test resistor; an output end of the amplifier unit is connected with a function end of the master control module; one end of the adjusting resistor is used for connecting a power supply, and the other end is connected with the positive input end of the amplifier unit.

[0009] Further, the oscillation module comprises a crystal unit, a first capacitor and a second capacitor; a first end of the crystal unit is connected with one end of the first capacitor and a synchronization end of the master control module respectively; a second end of the crystal unit is connected with one end of the second capacitor and the synchronization end of the master control module respectively; the other end of the first capacitor and the other end of the second capacitor are grounded.

[0010] Further, the reference capacitor module comprises at least two parallel capacitor groups; one end of the reference capacitor group is connected with a reference end of the master control module; the other end of the reference capacitor is connected with the reference end of the master control module and grounded.

[0011] Further, the master control module comprises a digital signal processing chip; a sampling pin of the digital signal processing chip is connected with an output end of the measured access module; an output pin of the digital signal processing chip is used for connecting a display device; a crystal pin of the digital signal processing chip is connected with the oscillation module; a reference pin of the digital signal processing chip is connected with the reference capacitor module.

[0012] Further, an amplification module is further included; an input end of the amplification module is connected with an output end of the master control module; the amplification module comprises at least two output branches of different frequencies for strobe connection with a display device.

[0013] Further, the amplification module comprises a first branch; the first branch comprises a first RC filter; an input end of the first RC filter is connected with an output end of the master control module, and an output end of the first RC filter is used for connecting a display device.

[0014] Further, the amplification module comprises a second branch; the second branch comprises a Butterworth low-pass filter and a second RC filter; an input end of the Butterworth low-pass filter is connected with an output end of the master control module, an output end of the Butterworth low-pass filter is connected with an input end of the second RC filter; an output end of the second RC filter is used for connecting a display device.

[0015] Further, the amplification module comprises a third branch; the third branch comprises a Bessel filter and a third RC filter; an input end of the Bessel filter is connected with an output end of the main control module, and an output end of the Bessel filter is connected with an input end of the third RC filter; and an output end of the third RC filter is used for being connected with a display device.

[0016] The utility model discloses beneficial effect lies in: through the sampling signal that measured access module generates, the common mode signal in sampling signal is handled and eliminated to signal acquisition module, simultaneously through oscillation module and reference capacitor module respectively for main control module provide accurate clock signal and reference voltage, make main control module can accurate operation, and the signal that will gather is converted into the digital signal of being recognized to main control module to calculate the harmonic component containing, exclude interference signal, relative to the mode of excluding interference based on band pass filter of prior art, can be applied to more scene. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is the module schematic drawing of a circuit for harmonic detection in the utility model embodiment;

[0018] Figure 2 It is the circuit connection schematic drawing of measured access module in a circuit for harmonic detection in the utility model embodiment;

[0019] Figure 3 It is the circuit connection schematic drawing of signal acquisition module in a circuit for harmonic detection in the utility model embodiment;

[0020] Figure 4 It is the circuit connection schematic drawing of oscillation module in a circuit for harmonic detection in the utility model embodiment;

[0021] Figure 5 It is the circuit connection schematic drawing of reference capacitor module in a circuit for harmonic detection in the utility model embodiment;

[0022] Label explanation:

[0023] 1, measured access module;SM, single-chip microcomputer;U1, drive chip;Q1, first MOS tube;Q2, second MOS tube;R1, test resistance;

[0024] 2, signal acquisition module;U2, amplifier unit;R2, adjusting resistance;

[0025] 3, main control module;4, oscillation module;X, crystal oscillator unit;C1, first capacitor;C2, second capacitor;5, reference capacitor module. DETAILED DESCRIPTION

[0026] The technical contents, purposes and effects of the utility model will be illustrated in detail in combination with the embodiments and the drawings.

[0027] A circuit for harmonic detection, comprising a measured access module, a signal acquisition module, a main control module, an oscillation module and a reference capacitor module; the measured access module is used for generating a sampling signal, and the output end of the measured access module is connected with the input end of the signal acquisition module; the output end of the signal acquisition module is connected with the function end of the main control module; the synchronous end of the main control module is connected with the oscillation module; the reference end of the main control module is connected with the reference capacitor module; and the output end of the main control module is used for connecting a display device.

[0028] From the above description, the utility model has the beneficial effects that: after the measured access module generates a sampling signal, the signal acquisition module processes and eliminates the common-mode signal in the sampling signal, at the same time, the oscillation module and the reference capacitor module respectively provide accurate clock signals and reference voltages for the main control module, so that the main control module can accurately operate, and the collected signal is converted into a digital signal that can be recognized by the main control module, thereby calculating the contained harmonic components and excluding interference signals, and compared with the existing interference exclusion mode based on a band-pass filter, the utility model can be applied to more scenes.

[0029] Further, the measured access module comprises a single-chip microcomputer, a drive chip, a first MOS tube, a second MOS tube and a test resistor; the output end of the single-chip microcomputer is connected with the input end of the drive chip; the source of the first MOS tube is used for being connected with a power supply, the drain of the first MOS tube is connected with the source of the second MOS tube; the drain of the second MOS tube is connected with one end of the test resistor; the output end of the drive chip is respectively connected with the gate of the first MOS tube and the gate of the second MOS tube; the other end of the test resistor is grounded, and the two ends of the test resistor are used as the output end of the measured access module.

[0030] From the above description, the first MOS tube and the second MOS tube form a half-bridge drive circuit, and the single-chip microcomputer is arranged to send a PWM signal for control, so as to drive the two MOS tubes of the half-bridge to output correspondingly, and the two ends of the test resistor are used as the input end of the signal acquisition circuit, so as to realize current sampling; at the same time, arranging the test resistor at the near-ground end of the second MOS tube can eliminate the common-mode interference possibly generated by the PWM signal when the single-chip microcomputer controls the drive chip.

[0031] Further, the signal acquisition module comprises an amplifier unit and an adjusting resistor; a positive input end of the amplifier unit is connected with one end of the test resistor; a negative input end of the amplifier unit is connected with the other end of the test resistor; an output end of the amplifier unit is connected with a function end of the master control module; one end of the adjusting resistor is used for connecting a power supply, and the other end is connected with the positive input end of the amplifier unit.

[0032] From the above description, it can be known that the two input ends of the amplifier are connected to the two ends of the test resistor, so as to collect and change the size of the current, and at the same time, the power supply is connected in parallel with the adjusting resistor at the positive input end of the amplifier, so as to adjust the size of the signal sampled by the amplifier.

[0033] Further, the oscillation module comprises a crystal oscillator unit, a first capacitor and a second capacitor; a first end of the crystal oscillator unit is connected with one end of the first capacitor and a synchronization end of the master control module respectively; a second end of the crystal oscillator unit is connected with one end of the second capacitor and the synchronization end of the master control module respectively; the other end of the first capacitor and the other end of the second capacitor are grounded.

[0034] From the above description, it can be known that the oscillation module is composed of the crystal oscillator unit, the first capacitor and the second capacitor, which can provide an accurate clock signal for the master control module, so as to realize fine time control and meet the demand of high-precision control.

[0035] Further, the reference capacitor module comprises at least two parallel capacitors to form a reference capacitor group; one end of the reference capacitor group is connected with a reference end of the master control module; the other end of the reference capacitor is connected with the reference end of the master control module and grounded.

[0036] From the above description, it can be known that the reference capacitor group is composed of multiple capacitors in parallel, so as to adjust the number and value of the capacitors according to the actual voltage demand, and provide a stable reference voltage for the master control module.

[0037] Further, the master control module comprises a digital signal processing chip; a sampling pin of the digital signal processing chip is connected with an output end of the measured access module; an output pin of the digital signal processing chip is used for connecting a display device; a crystal oscillator pin of the digital signal processing chip is connected with the oscillation module; and a reference pin of the digital signal processing chip is connected with the reference capacitor module.

[0038] From the above description, it can be known that the digital signal processing chip is used as the master control module, and the pins of the digital signal processing chip are connected with other modules for collaborative control, so as to realize the functions of signal acquisition, signal conversion, harmonic component calculation and the like.

[0039] Further, the amplification module is further included; the input end of the amplification module is connected with the output end of the main control module; the amplification module includes at least two output branches of different frequencies for being connected with the display device.

[0040] From the above description, by setting the amplification module, and the output end of the amplification module is divided into multiple amplification branches, so that the access of different models of display devices can be met.

[0041] Further, the amplification module includes a first branch; the first branch includes a first RC filter; the input end of the first RC filter is connected with the output end of the main control module, and the output end of the first RC filter is used for being connected with the display device.

[0042] From the above description, the first RC filter is used as the first branch, so that the signal with the output frequency not higher than the first preset frequency can be limited.

[0043] Further, the amplification module includes a second branch; the second branch includes a Butterworth low-pass filter and a second RC filter; the input end of the Butterworth low-pass filter is connected with the output end of the main control module, the output end of the Butterworth low-pass filter is connected with the input end of the second RC filter, and the output end of the second RC filter is used for being connected with the display device.

[0044] From the above description, the second branch is composed of the Butterworth low-pass filter and the second RC filter, so that the output signal with the output frequency in the second preset frequency band can be limited.

[0045] Further, the amplification module includes a third branch; the third branch includes a Bessel filter and a third RC filter; the input end of the Bessel filter is connected with the output end of the main control module, the output end of the Bessel filter is connected with the input end of the third RC filter, and the output end of the third RC filter is used for being connected with the display device.

[0046] From the above description, the third branch is composed of the Bessel filter and the third RC filter, so that the output signal with the output frequency in the third preset frequency band can be limited.

[0047] The circuit for harmonic detection provided by the utility model can be applied to the current harmonic detection scene, and the following is described through a specific embodiment.

[0048] Embodiment one

[0049] Please refer to Figure 1The application relates to a circuit for harmonic detection, which comprises a measured access module 1, a signal collection module 2, a main control module 3, an oscillation module 4 and a reference capacitor module 5; the measured access module 1 is used for generating a sampling signal, and the output end of the measured access module 1 is connected with the input end of the signal collection module 2; the output end of the signal collection module 2 is connected with the function end of the main control module 3; the synchronous end of the main control module 3 is connected with the oscillation module 4; the reference end of the main control module 3 is connected with the reference capacitor module 5; and the output end of the main control module 3 is used for connecting a display device.

[0050] Please refer to Figure 2 The measured access module 1 comprises a single-chip microcomputer SM, a driving chip U1, a first MOS tube Q1, a second MOS tube Q2 and a test resistor R1; wherein the measured access module 1 is used for simulating a measured circuit, in an optional embodiment, the driving chip U1 adopts an IR2101 chip; the output end of the single-chip microcomputer SM is connected with the input end of the driving chip U1; the source electrode of the first MOS tube Q1 is used for being connected with a power supply, the drain electrode of the first MOS tube Q1 is connected with the source electrode of the second MOS tube Q2; the drain electrode of the second MOS tube Q2 is connected with one end of the test resistor R1; the output end of the driving chip U1 is respectively connected with the gate electrode of the first MOS tube Q1 and the gate electrode of the second MOS tube Q2, specifically, the gate electrode of the first MOS tube Q1 and the gate electrode of the second MOS tube Q2 are also connected to the driving chip U1 through a resistor in series, so that the first MOS tube Q1 and the second MOS tube Q2 form a half-bridge structure; the IR2101 chip is controlled by the PWM signal sent by the single-chip microcomputer SM, so as to drive the two MOS tubes of the half-bridge to output correspondingly; the other end of the test resistor R1 is grounded, and the two ends of the test resistor R1 are used as the output end of the measured access module 1, that is, the two ends (a node 1 and a node 2) of the test resistor R1 are used as the input end of the signal collection module 2, so as to realize current sampling; meanwhile, since the test resistor R1 is arranged at the near-ground end of the second MOS tube Q2, the common-mode interference generated by the PWM signal when the single-chip microcomputer SM controls the driving chip U1 can be eliminated.

[0051] Please refer to Figure 3 The signal collection module 2 comprises an amplifier unit U2 and an adjusting resistor R2; the positive-phase input end of the amplifier unit U2 is connected with one end (a node 1) of the test resistor R1 through a sampling resistor (R3), and the inverting-phase input end of the amplifier unit U2 is also connected with the other end (a node 2) of the test resistor R1 through a sampling resistor (R4); the output end of the amplifier unit U2 is connected with the function end of the main control module 3; one end of the adjusting resistor R2 is used for being connected with a power supply, and the other end is connected with the positive-phase input end of the amplifier unit U2, so as to adjust the signal size sampled by the amplifier unit U2.

[0052] Please refer to Figure 4 andFigure 5 The oscillation module 4 comprises a crystal unit X, a first capacitor C1 and a second capacitor C2; a first end of the crystal unit X is connected with one end of the first capacitor C1 and a synchronization end of the master control module 3 respectively; a second end of the crystal unit X is connected with one end of the second capacitor C2 and the synchronization end of the master control module 3 respectively; the other end of the first capacitor C1 and the other end of the second capacitor C2 are grounded; the oscillation module 4 is an external crystal oscillator, which is used to provide an accurate clock signal to realize fine time control and meet the high-precision requirement. The reference capacitor module 5 comprises at least two parallel capacitor groups; one end of the reference capacitor group is connected with a reference end of the master control module 3; the other end of the reference capacitor is connected with the reference end of the master control module 3 and grounded; as shown in FIG. 4, the reference capacitor group is composed of the capacitor C7 and the capacitor C8; the reference capacitor module 5 is used to provide a stable reference voltage, so as to ensure that the analog-to-digital converter built in the master control module 3 can accurately operate, and convert the collected signal into a digital signal which can be processed by the master control module 3, so as to calculate the harmonic components contained. Figure 5

[0053] In an optional embodiment, the master control module 3 comprises a digital signal processing chip (DSP); a sampling pin of the digital signal processing chip is connected with the output end of the measured access module 1; an output pin of the digital signal processing chip is used to be connected with a display device; a crystal oscillator pin of the digital signal processing chip is connected with the oscillation module 4; a reference pin of the digital signal processing chip is connected with the reference capacitor module 5; specifically, for example, the reset end is a reset pin, the function end contains SCLK and CS pins, the output end includes DIN and DOUT pins, the synchronization end is an OSC pin, and the reference end is a refcap pin.

[0054] Wherein, before the result is output to the display device, an amplification module can be additionally provided based on the different signal frequencies of the measured line and the different working ranges of the display device; the amplification module is a multi-terminal amplification circuit, an input end of the amplification module is connected with an output end of the master control module 3; the amplification module comprises at least two output branches of different frequencies which are used to be connected with the display device; that is, the output of the amplification module is divided into multiple amplification branches, so as to be able to meet the access of more models of display devices, for example, in the embodiment, it is divided into three branches;

[0055] The first branch comprises a first RC filter; an input end of the first RC filter is connected with an output end of the master control module 3, and an output end of the first RC filter is used to be connected with the display device, for limiting the signal whose frequency is not higher than frequency A.

[0056] ​The second branch includes a Butterworth low-pass filter and a second RC filter; an input end of the Butterworth low-pass filter is connected with an output end of the main control module 3, an output end of the Butterworth low-pass filter is connected with an input end of the second RC filter; an output end of the second RC filter is used for being connected with a display device, for limiting an output signal of the output frequency A-B.

[0057] The third branch includes a Bessel filter and a third RC filter; an input end of the Bessel filter is connected with an output end of the main control module 3, an output end of the Bessel filter is connected with an input end of the third RC filter; an output end of the third RC filter is used for being connected with a display device, for limiting an output signal of the output frequency B-C. Among the three branches, the first branch has the lowest cost, is mainly suitable for a low-frequency type scene; the passband response and roll-off speed of the second branch are also the flattest; the response speed and signal distortion of the third branch are the smallest. When testing, a corresponding branch can be freely selected from the above three branches and connected with the display device according to test requirements, having high flexibility; without needing to select a corresponding type of display device for different test signals every time, time and cost are saved.

[0058] The above only describes the embodiments of the present application, and does not limit the patent range of the present application, and any equivalent transformation or direct or indirect application in the related technical field by using the content of the present application specification and drawings is also included in the patent protection range of the present application.

Claims

1. A circuit for harmonic detection, characterized in that, It includes the under-test access module, signal acquisition module, main control module, oscillation module, and reference capacitor module; The access module under test is used to generate a sampling signal, and the output terminal of the access module under test is connected to the input terminal of the signal acquisition module. The output terminal of the signal acquisition module is connected to the functional terminal of the main control module; The synchronization terminal of the main control module is connected to the oscillation module; The reference terminal of the main control module is connected to the reference capacitor module; The output of the main control module is used to connect to the display device.

2. The circuit for harmonic detection according to claim 1, characterized in that, The tested access module includes a microcontroller, a driver chip, a first MOSFET, a second MOSFET, and a test resistor; The output terminal of the microcontroller is connected to the input terminal of the driver chip; The source of the first MOSFET is connected to the power supply, and the drain of the first MOSFET is connected to the source of the second MOSFET. The drain of the second MOS transistor is connected to one end of the test resistor; The output terminal of the driver chip is connected to the gate of the first MOS transistor and the gate of the second MOS transistor, respectively. The other end of the test resistor is grounded, and both ends of the test resistor serve as the output terminals of the connected module under test.

3. The circuit for harmonic detection according to claim 2, characterized in that, The signal acquisition module includes an amplifier unit and an adjustment resistor; The non-inverting input terminal of the amplifier unit is connected to one end of the test resistor; The inverting input terminal of the amplifier unit is connected to the other end of the test resistor; The output terminal of the amplifier unit is connected to the functional terminal of the main control module; One end of the regulating resistor is used to connect to the power supply, and the other end is connected to the non-inverting input terminal of the amplifier unit.

4. The circuit for harmonic detection according to claim 1, characterized in that, The oscillation module includes a crystal oscillator unit, a first capacitor, and a second capacitor; The first end of the crystal oscillator unit is connected to one end of the first capacitor and the synchronization end of the main control module, respectively. The second end of the crystal oscillator unit is connected to one end of the second capacitor and the synchronization terminal of the main control module, respectively. The other end of the first capacitor and the other end of the second capacitor are grounded.

5. The circuit for harmonic detection according to claim 1, characterized in that, The reference capacitor module includes at least two capacitors connected in parallel to form a reference capacitor group; One end of the reference capacitor bank is connected to the reference terminal of the main control module; The other end of the reference capacitor is connected to the reference terminal of the main control module and grounded.

6. The circuit for harmonic detection according to claim 1, characterized in that, The main control module includes a digital signal processing chip; The sampling pin of the digital signal processing chip is connected to the output terminal of the access module under test; The output pins of the digital signal processing chip are used to connect to a display device; The crystal pin of the digital signal processing chip is connected to the oscillation module; The reference pin of the digital signal processing chip is connected to the reference capacitor module.

7. The circuit for harmonic detection according to claim 1, characterized in that, It also includes an amplification module; The input terminal of the amplification module is connected to the output terminal of the main control module; The amplification module includes at least two output branches with different frequencies for selective connection to the display device.

8. The circuit for harmonic detection according to claim 7, characterized in that, The amplification module includes a first branch; The first branch includes a first RC filter; The input terminal of the first RC filter is connected to the output terminal of the main control module, and the output terminal of the first RC filter is used to connect to the display device.

9. A circuit for harmonic detection according to claim 7, characterized in that, The amplification module includes a second branch; The second branch includes a Butterworth low-pass filter and a second RC filter; The input terminal of the Butterworth low-pass filter is connected to the output terminal of the main control module, and the output terminal of the Butterworth low-pass filter is connected to the input terminal of the second RC filter. The output of the second RC filter is used to connect to a display device.

10. A circuit for harmonic detection according to claim 7, characterized in that, The amplification module includes a third branch; The third branch includes a Bessel filter and a third RC filter; The input terminal of the Bessel filter is connected to the output terminal of the main control module, and the output terminal of the Bessel filter is connected to the input terminal of the third RC filter. The output of the third RC filter is used to connect to a display device.

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