CN213986780U - Grounding downlead conduction tester with high testing speed - Google Patents
Grounding downlead conduction tester with high testing speed Download PDFInfo
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- CN213986780U CN213986780U CN202023019931.6U CN202023019931U CN213986780U CN 213986780 U CN213986780 U CN 213986780U CN 202023019931 U CN202023019931 U CN 202023019931U CN 213986780 U CN213986780 U CN 213986780U
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Abstract
The utility model provides a fast ground connection downlead conduction tester of test speed, through setting up photoelectric isolation circuit, keep apart the interference of preceding stage and back stage circuit, the signal of photoelectric isolation circuit output has linear stability for the sinusoidal alternating current signal of signal generation chip AD9850 output keeps stable; the voltage-dividing bias amplifying circuit is arranged to amplify the power of the sine alternating current signal output by the sine wave generating circuit, stabilize the static working point of the field effect transistor Q1 and eliminate the zero drift of the field effect transistor Q1, so that the stability of the output sine alternating current signal is further improved; by arranging the isolation circuit, the coupling between the sinusoidal alternating current signal output by the voltage-dividing bias amplifying circuit and the power supply and the ground is eliminated, the direct current signal is isolated, the sinusoidal alternating current signal is prevented from sudden change caused by the coupling between the power supply and the ground, and the stability of the sinusoidal alternating current signal output after being processed by the voltage-dividing bias amplifying circuit is further improved.
Description
Technical Field
The utility model relates to a ground connection downlead conduction test technical field especially relates to a fast ground connection downlead conduction tester of test.
Background
At present, the resistance of the grounding downlead is measured in a power transmission project by a clamp meter method, a grounding pole does not need to be laid during measurement, a sine wave generating circuit sends out sine alternating current signals, the sine wave alternating current signals are amplified by a power amplifying circuit and then input to a voltage transformer, the voltage transformer is driven to serve as a voltage pole, and the current transformer serves as a current pole, so that the labor intensity of electric power inspection workers can be greatly reduced, and the resistance measurement work of the tower grounding downlead is more convenient and faster. The sine wave alternating current signal is crucial to a detection result of the ground down conductor conduction tester, in order to improve driving capability, a complementary push-pull type power amplification circuit is usually adopted in an existing power amplification circuit, although the sine wave alternating current signal output after being processed by the complementary push-pull type power amplification circuit has enough power and meets the driving requirement of a voltage transformer, the problem that the output sine wave alternating current signal is unstable due to the fact that the sine wave alternating current signal is easily influenced by noise and impedance mismatching exists.
Therefore, in order to solve the above problem, the utility model provides a fast ground connection downlead conduction tester of test through optimizing current complementary push-pull power amplifier circuit, the strong impedance of interference immunity of circuit and the impedance match of circuit improve the stability of the sinusoidal alternating current signal of output.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a fast ground connection downlead conduction tester tests, through optimizing current complementary push-pull power amplifier circuit, the strong impedance of interference immunity and the impedance match of circuit improve the stability of the sinusoidal alternating signal of output.
The technical scheme of the utility model is realized like this: the utility model provides a grounding downlead conduction tester with high testing speed, which comprises a CPU chip, a voltage transformer, a voltage detection module, a sine wave generating circuit, a power supply, a voltage division type bias amplifying circuit and a T-shaped matching circuit;
the output end of the sine wave generating circuit is electrically connected with the input end of the voltage-dividing bias amplifying circuit, the power supply is electrically connected with the power supply end of the voltage-dividing bias amplifying circuit, the output end of the voltage-dividing bias amplifying circuit is electrically connected with the input end of the T-shaped matching circuit, the output end of the T-shaped matching circuit is electrically connected with one end of the grounding down lead and the input end of the voltage detection module through the voltage transformer respectively, the output end of the voltage detection module is electrically connected with the analog input end of the CPU chip, and the other end of the grounding down lead outputs a current signal.
On the basis of the above technical solution, preferably, the power supply further comprises an isolation circuit;
the power supply is electrically connected with the input end of the isolation circuit, and the output end of the isolation circuit is electrically connected with the output end of the voltage division type bias amplifying circuit.
Still further preferably, the voltage division bias amplifying circuit comprises resistors R1-R3, a capacitor C1, a capacitor C2 and a field effect transistor Q1;
the output end of the sine wave generating circuit is electrically connected with one end of a resistor R1, one end of a resistor R2, one end of a resistor R3 and the grid of a field-effect tube Q1 through a capacitor C1 respectively, the other end of the resistor R1 is electrically connected with a power supply, the other end of a resistor R2 is grounded, the other end of the resistor R3 is grounded through a capacitor C2, the source of a field-effect tube Q1 is grounded, and the drain of the field-effect tube Q1 is electrically connected with the output end of the isolating circuit and the input end of the T-type matching circuit respectively.
Still further preferably, the isolation circuit comprises a polar capacitor C3 and a radio frequency choke RFC;
the power supply is respectively electrically connected with one end of the radio frequency choke RFC and the anode of the polar capacitor C3, the cathode of the polar capacitor C3 is grounded, and the other end of the radio frequency choke RFC is electrically connected with the drain of the field effect transistor Q1.
Still further preferably, the T-type matching circuit includes an inductor L1, a variable capacitor C4, and a variable capacitor C5;
the drain of the field effect transistor Q1 is electrically connected to one end of the variable capacitor C4 and one end of the variable capacitor C5 through the inductor L1, respectively, the other end of the variable capacitor C5 is grounded, and the other end of the variable capacitor C4 is electrically connected to the input end of the voltage transformer.
On the basis of the above technical solution, preferably, the sine wave generating circuit includes a signal generating chip AD9850 and a photoelectric isolation circuit;
the RF _ OUT terminal of the signal generating chip AD9850 is electrically connected with the input terminal of the voltage division type bias amplifying circuit through the photoelectric isolation circuit.
Still further preferably, the optoelectronic isolation circuit comprises a capacitor C6, a capacitor C7, resistors R13-R15, a first operational amplifier LM741, a second operational amplifier LM741 and a linear optocoupler HCNR 201;
the RF _ OUT terminal of the signal generating chip AD9850 is electrically connected to the inverting input terminal of the first operational amplifier LM741 and the third pin of the linear optocoupler HCNR201 through a resistor R13, the non-inverting input end of the first operational amplifier LM741 is grounded, the capacitor C6 is connected in parallel between the inverting input end of the first operational amplifier LM741 and the output end thereof, the output end of the first operational amplifier LM741 is electrically connected with the first pin of the linear optical coupler HCNR201 through the resistor R15, the fourth pin and the fifth pin of the linear optical coupler HCNR201 are grounded, the sixth pin of the linear optical coupler HCNR201 is electrically connected with the inverting input end of the second operational amplifier LM741, the non-inverting input end of the second operational amplifier LM741 is grounded, the resistor R14 is connected in parallel between the inverting input end of the second operational amplifier LM741 and the output end thereof, the capacitor C7 is connected in parallel at two ends of the resistor R14, and the output end of the second operational amplifier LM741 is electrically connected with the input end of the voltage-dividing bias amplifying circuit.
On the basis of the technical scheme, the current transformer and the current detection module are preferably further included;
the current transformer collects current on the grounding down lead and inputs a current signal corresponding to the current to the input end of the current detection module, and the output end of the current detection module is electrically connected with the analog input end of the CPU chip.
The utility model discloses a fast ground connection downlead conduction tester of test has following beneficial effect for prior art:
(1) the interference between the front-stage circuit and the rear-stage circuit is isolated by arranging the photoelectric isolation circuit, and the signal output by the photoelectric isolation circuit has linear stability, so that the sinusoidal alternating current signal output by the signal generation chip AD9850 is kept stable;
(2) the voltage-dividing bias amplifying circuit is arranged to amplify the power of the sine alternating current signal output by the sine wave generating circuit, stabilize the static working point of the field effect transistor Q1 and eliminate the zero drift of the field effect transistor Q1, so that the stability of the output sine alternating current signal is further improved;
(3) by arranging the isolation circuit, the coupling between the sinusoidal alternating current signal output by the voltage division type bias amplifying circuit and the power supply and the ground is eliminated, the direct current signal is isolated, the sinusoidal alternating current signal is prevented from sudden change caused by the coupling between the power supply and the ground, and the stability of the sinusoidal alternating current signal output after being processed by the voltage division type bias amplifying circuit is further improved;
(4) by arranging the T-shaped matching circuit, on one hand, the output impedance of the voltage division type bias amplifying circuit is matched with the impedance of the voltage transformer, so that the power loss of the sinusoidal alternating current signal output by the voltage division type bias amplifying circuit is reduced, and the stability of the output sinusoidal alternating current signal is improved; and on the other hand, the voltage-dividing bias amplifying circuit is used for tuning, so that the sinusoidal alternating current signal current output by the voltage-dividing bias amplifying circuit is in phase with the voltage, the reactive loss of the voltage-dividing bias amplifying circuit is further reduced, and the power and the stability of the sinusoidal alternating current signal output by the voltage-dividing bias amplifying circuit are improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a system structure diagram of a fast testing ground down conduction tester of the present invention;
fig. 2 is a circuit diagram of the voltage-dividing bias amplifying circuit, the isolating circuit and the T-type matching circuit in the ground down lead conduction tester with high testing speed of the present invention;
fig. 3 is the utility model discloses a fast ground connection downlead conduction tester's of test circuit diagram of optoelectronic isolation circuit.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to 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 in the present invention, all other embodiments obtained by a person skilled in the art without creative work all belong to the protection scope of the present invention.
As shown in fig. 1, the utility model discloses a fast ground connection downlead conduction tester of test, it includes CPU chip, current transformer, current detection module, voltage detection module and sine wave generating circuit, power, partial pressure formula biasing amplifier circuit, buffer circuit, T type matching circuit.
And the sine wave generating circuit provides a sine alternating current signal for the voltage transformer to drive the voltage transformer to work. In this embodiment, the output terminal of the sine wave generating circuit is electrically connected to the input terminal of the voltage-dividing bias amplifying circuit. Preferably, in this embodiment, the sine wave generating circuit includes a signal generating chip AD9850 and an optoelectronic isolating circuit.
And the signal generation chip AD9850 is used for providing a sinusoidal alternating current signal for the voltage transformer and driving the voltage transformer to work. The RF _ OUT terminal of the signal generating chip AD9850 is electrically connected with the input terminal of the voltage division type bias amplifying circuit through the photoelectric isolation circuit. The RF _ OUT terminal of the signal generating chip AD9850 corresponds to the output terminal of the sine wave generating circuit. In this embodiment, the internal algorithm and the structure of the signal generating chip AD9850 are not improved, and therefore, the internal algorithm and the structure of the signal generating chip AD9850 are not described in detail herein.
The sine alternating current signal output by the signal generation chip AD9850 is usually provided with direct current bias and limited driving capability; the existing photoelectric isolation circuit usually uses optical coupler isolation alone, and the nonlinear problem of the optical coupler exists, so that the output signal is unstable; therefore, in the present embodiment, the optoelectronic isolation circuit is arranged to isolate interference between the front stage circuit and the rear stage circuit, and the signal output by the optoelectronic isolation circuit has linear stability, so that the sinusoidal ac signal output by the signal generating chip AD9850 is kept stable. In this embodiment, the optoelectronic isolation circuit is connected in series in a line between the RF _ OUT terminal of the signal generating chip AD9850 and the input terminal of the voltage-dividing bias amplifying circuit. Preferably, in this embodiment, as shown in fig. 3, the optoelectronic isolation circuit includes a capacitor C6, a capacitor C7, resistors R13-R15, a first operational amplifier LM741, a second operational amplifier LM741, and a linear optocoupler HCNR 201; specifically, an RF _ OUT terminal of the signal generating chip AD9850 is electrically connected to an inverting input terminal of the first operational amplifier LM741 and a third pin of the linear optocoupler HCNR201 through a resistor R13, a non-inverting input terminal of the first operational amplifier LM741 is grounded, a capacitor C6 is connected in parallel between the inverting input terminal of the first operational amplifier LM741 and an output terminal thereof, an output terminal of the first operational amplifier LM741 is electrically connected to the first pin of the linear optocoupler HCNR201 through a resistor R15, a fourth pin and a fifth pin of the linear optocoupler HCNR201 are grounded, a sixth pin of the linear optocoupler HCNR201 is electrically connected to an inverting input terminal of the second operational amplifier LM741, a non-inverting input terminal of the second operational amplifier LM741 is grounded, a resistor R14 is connected in parallel between the inverting input terminal of the second operational amplifier LM741 and the output terminal thereof, a capacitor C7 is connected in parallel to both ends of the resistor R14, and an output terminal of the second operational amplifier LM741 is electrically connected to an input terminal of the voltage-dividing bias amplifying circuit. As shown in fig. 3, Vi denotes a sinusoidal ac signal output from the signal generation chip AD 9850; vo1 represents the sinusoidal ac signal output by the opto-electronic isolation circuit; u2 denotes a first operational amplifier LM 741.
The resistor R13 is a current-limiting resistor, and prevents the sinusoidal alternating current signal output by the signal generation chip AD9850 from breaking through the first operational amplifier LM741 due to overlarge; the capacitor C7 is a negative feedback capacitor and is used for preventing the first operational amplifier LM741 from self-oscillation and reducing nonlinear distortion; the first operational amplifier LM741 is used for converting the sinusoidal alternating current signal output by the generating chip AD9850 into a stable current signal and improving the stability of the voltage signal output by the photoelectric isolation circuit; the resistor R15 is a current-limiting resistor, and prevents the linear optocoupler HCNR201 from being damaged by overlarge output current of the first operational amplifier LM 741; the linear optocoupler HCNR201 is used for isolating interference of the first operational amplifier LM741 and the second operational amplifier LM741, and performing negative feedback on the first operational amplifier LM741, so that the stability of current output by the first operational amplifier LM741 is improved, and the stability of a voltage signal output by the photoelectric isolation circuit is further improved; the resistor R14, the capacitor C8 and the second operational amplifier LM741 form a negative feedback operational amplifier, current signals output by the linear optocoupler HCNR201 are converted into voltage signals again, the voltage signals output by the photoelectric isolation circuit are only related to the ratio of the resistor R13 to the resistor R14, and the resistance values of the resistor R13 and the resistor R14 are not changed, so that the signals output by the photoelectric isolation circuit have linear stability, and the stability of sinusoidal alternating current signals output by the photoelectric isolation circuit is further improved.
And the power supply provides working voltage for the voltage-dividing type bias amplifying circuit. Specifically, the power supply is electrically connected to the power supply terminal of the voltage-dividing bias amplifier circuit and the input terminal of the isolation circuit. In this embodiment, the improvement of the power supply structure is not involved, and therefore, the circuit structure of the power supply is not described again. As shown in fig. 2, VCC denotes a power supply.
The voltage-dividing bias amplifying circuit amplifies the power of the sine alternating current signal output by the sine wave generating circuit, stabilizes the static working point of the field effect transistor Q1, and eliminates the zero drift of the field effect transistor Q1, thereby further improving the stability of the output sine alternating current signal. In this embodiment, a power source end of the voltage division bias amplifying circuit is electrically connected to a power source, an input end of the voltage division bias amplifying circuit is electrically connected to an output end of the sine wave generating circuit, and an output end of the voltage division bias amplifying circuit is electrically connected to an output end of the isolating circuit and an input end of the T-type matching circuit, respectively. Preferably, in this embodiment, as shown in fig. 2, the voltage division bias amplifying circuit includes resistors R1-R3, a capacitor C1, a capacitor C2, and a field effect transistor Q1; the output end of the sine wave generating circuit is electrically connected with one end of a resistor R1, one end of a resistor R2, one end of a resistor R3 and the grid of a field-effect tube Q1 through a capacitor C1 respectively, the other end of the resistor R1 is electrically connected with a power supply, the other end of a resistor R2 is grounded, the other end of the resistor R3 is grounded through a capacitor C2, the source of a field-effect tube Q1 is grounded, and the drain of the field-effect tube Q1 is electrically connected with the output end of the isolating circuit and the input end of the T-type matching circuit respectively. As shown in fig. 2, the other end of the resistor R1 corresponds to the power supply terminal of the voltage-dividing bias amplifier circuit.
The power supply is used for supplying working voltage to the field effect transistor Q1; the capacitor C1 is a coupling capacitor and is used for isolating direct current components in the sine wave signals output by the sine wave generating circuit; the resistor R1 and the resistor R2 are voltage-dividing bias resistors, and the resistor R1 is used for stabilizing the static working point of the field-effect transistor Q1 so that the field-effect transistor Q1 always works in an amplification region; the resistor R2 is used for stabilizing the grid bias voltage of the field effect transistor Q1, eliminating the zero drift of the field effect transistor Q1 and improving the anti-interference performance of the field effect transistor; the resistor R3 and the capacitor C2 are protection circuits and are used for preventing the grid voltage of the field effect transistor Q1 from suddenly changing and breaking down the field effect transistor Q1; the field effect transistor Q1 is an amplifier transistor for amplifying the sinusoidal ac signal output from the output terminal of the sinusoidal wave generating circuit. The power supply, the resistors R1-R3, the capacitor C1, the capacitor C2 and the field effect transistor Q1 form a voltage division type bias amplifying circuit, the power of a sine alternating current signal output by the output end of the sine wave generating circuit is amplified, the static working point of the field effect transistor Q1 is stabilized, zero drift of the field effect transistor Q1 is eliminated, and therefore the stability of the output sine alternating current signal is improved.
The isolation circuit eliminates the coupling between the sinusoidal alternating current signal output by the voltage division type bias amplifying circuit and the power supply and the ground, isolates the direct current signal, prevents the sinusoidal alternating current signal output by the voltage division type bias amplifying circuit from sudden change due to the coupling between the power supply and the ground, and further improves the stability of the sinusoidal alternating current signal output after being processed by the voltage division type bias amplifying circuit. In this embodiment, the input terminal of the isolation circuit is electrically connected to the power supply, and the output terminal of the isolation circuit is electrically connected to the output terminal of the voltage-dividing bias amplifier circuit. Preferably, in this embodiment, as shown in fig. 2, the isolation circuit includes a polar capacitor C3 and a radio frequency choke RFC; specifically, the power supply is electrically connected with one end of the radio frequency choke RFC and the anode of the polar capacitor C3 respectively, the cathode of the polar capacitor C3 is grounded, and the other end of the radio frequency choke RFC is electrically connected with the drain of the field effect transistor Q1; wherein, one end of the radio frequency choke RFC correspondingly represents the input end of the isolation circuit; the other end of the radio frequency choke RFC correspondingly represents the output end of the isolation circuit. The RFC is used for eliminating the coupling between an alternating current signal output by the voltage division type bias amplifying circuit and a power supply and the ground; the capacitor C3 is a blocking capacitor, and isolates the direct current path from the alternating current path, thereby further improving the stability of the sinusoidal alternating current signal output by the voltage division type bias amplifying circuit.
On one hand, the T-shaped matching circuit enables the output impedance of the voltage division type bias amplifying circuit to be matched with the impedance of the voltage transformer, reduces the power loss of the sine alternating current signal output by the voltage division type bias amplifying circuit, and improves the stability of the output sine alternating current signal; and on the other hand, the voltage-dividing bias amplifying circuit is used for tuning, so that the sinusoidal alternating current signal current output by the voltage-dividing bias amplifying circuit is in phase with the voltage, the reactive loss of the voltage-dividing bias amplifying circuit is further reduced, and the power and the stability of the sinusoidal alternating current signal output by the voltage-dividing bias amplifying circuit are improved. In this embodiment, an input end of the T-type matching circuit is electrically connected to an output end of the voltage division bias amplifying circuit, and an output end of the T-type matching circuit is electrically connected to one end of the ground down lead and an input end of the voltage detection module through the voltage transformer, respectively. Preferably, in this embodiment, as shown in fig. 2, the T-type matching circuit includes an inductor L1, a variable capacitor C4, and a variable capacitor C5; specifically, the drain of the field effect transistor Q1 is electrically connected to one end of the variable capacitor C4 and one end of the variable capacitor C5 through the inductor L1, respectively, the other end of the variable capacitor C5 is grounded, and the other end of the variable capacitor C4 is electrically connected to the input end of the voltage transformer. Vo2 represents the sinusoidal ac signal output by the T-type matching circuit, as shown in fig. 2.
On one hand, the variable capacitor C4 and the variable capacitor C5 are used for tuning and adjusting the phase of the current and the voltage of the sinusoidal alternating current signal output by the voltage division bias amplification circuit so as to reduce the reactive loss in the circuit; on the other hand, the voltage-dividing type bias amplifying circuit is used for filtering harmonic components of the sinusoidal alternating current signal output by the voltage-dividing type bias amplifying circuit, and further improving the power of the sinusoidal alternating current signal output by the voltage-dividing type bias amplifying circuit, so that the stability of the output sinusoidal alternating current signal is improved; the inductor L2 resonates with the variable capacitor C4 and the variable capacitor C5, so that the output impedance of the voltage division type bias amplifying circuit is matched with the impedance of the voltage transformer, and the power and the stability of the sinusoidal alternating current signal output by the voltage division type bias amplifying circuit are improved.
The voltage transformer is a voltage pole of the grounding down conductor conduction tester, the voltage transformer starts to work after receiving a sinusoidal alternating current signal output by the T-shaped matching circuit, induced electromotive force is generated, the grounding down conductor is electrified, a voltage signal is output to the voltage detection module, and the voltage signal is amplified and filtered by the voltage detection module and then input to the CPU chip. In this embodiment, an input end of the voltage transformer is electrically connected to an output end of the T-type matching circuit, an output end of the voltage transformer is electrically connected to one end of the ground down lead and an input end of the voltage detection module, an output end of the voltage detection module is electrically connected to an analog input end of the CPU chip, and the other end of the ground down lead outputs a current signal. In this embodiment, the structure of the voltage transformer and the voltage detection module is not improved, and therefore, the circuit structures of the voltage transformer and the voltage detection module are not described in detail herein. Preferably, JDZ (X) -3, 6 and 10 can be used as the voltage transformer.
The current transformer is a current pole of the grounding down lead conduction tester, when the voltage transformer generates induced electromotive force, the grounding down lead is electrified and current is generated, the current transformer collects current signals on the grounding down lead, and the current signals are input to the current detection module to be subjected to I/V conversion, filtering and rectification processing and then are input to the CPU chip. In this embodiment, the input terminal of the current transformer is electrically connected to the other end of the ground down conductor, the output terminal of the current transformer is electrically connected to the input terminal of the current detection module, and the output terminal of the current detection module is electrically connected to the analog input terminal of the CPU chip. In this embodiment, the structure of the current transformer and the current detection module is not improved, and therefore, the circuit structures of the current transformer and the current detection module are not described in detail herein. Preferably, the current transformer can be selected from LZBJ 9-10A.
And the CPU chip receives the voltage signal output by the voltage acquisition module and the electric signal output by the current acquisition module and obtains the resistance value of the grounding down lead according to the two paths of electric signals. In this embodiment, the analog input terminal of the CPU chip is electrically connected to the output terminal of the current detection module, and the analog input terminal of the CPU chip is electrically connected to the output terminal of the voltage detection module. In this embodiment, the improvement of the internal algorithm and the structure of the CPU chip is not involved, and therefore, the internal algorithm and the structure of the CPU chip are not described in detail herein. Preferably, the CPU chip can adopt MSP 430; wherein the end P1.1 correspondingly represents an analog input end connected with the voltage detection module; the end P1.2 corresponds to an analog input end connected with the current detection module.
The utility model discloses a theory of operation is: the signal generating chip outputs a sinusoidal alternating current signal, the sinusoidal alternating current signal is isolated from the interference between a front-stage circuit and a rear-stage circuit by a photoelectric isolation circuit, the photoelectric isolation circuit outputs a linear sinusoidal alternating current signal to a voltage division bias amplifying circuit, the voltage division bias amplifying circuit amplifies the power of the sinusoidal alternating current signal and eliminates zero drift of the circuit, meanwhile, the isolation circuit eliminates the coupling between the sinusoidal alternating current signal output by the voltage division bias amplifying circuit and a power supply and the ground, the voltage division bias amplifying circuit inputs the processed sinusoidal alternating current signal to a T-shaped matching circuit, the T-shaped matching circuit enables the output impedance of the voltage division bias amplifying circuit to be matched with the impedance of a voltage transformer, enables the current and the voltage of the sinusoidal alternating current signal output by the voltage division bias amplifying circuit to be in phase, outputs a stable sinusoidal alternating current signal to the voltage transformer and drives the voltage transformer to generate electromotive force, one path of the electromotive force is output to a voltage detection module, and the voltage detection module collects a voltage signal corresponding to the electromotive force, amplifies and filters the voltage signal and inputs the amplified voltage signal to a CPU chip; and the other path of the current is input to the grounding down lead, at the moment, the grounding down lead is electrified and generates current, the current transformer collects a current signal on the grounding down lead, the current signal is input to the current detection module to be subjected to I/V conversion, filtering and rectification, and then is input to the CPU chip, and finally the CPU chip obtains the resistance value of the grounding down lead according to the received signal.
The beneficial effect of this embodiment does: the interference between the front-stage circuit and the rear-stage circuit is isolated by arranging the photoelectric isolation circuit, and the signal output by the photoelectric isolation circuit has linear stability, so that the sinusoidal alternating current signal output by the signal generation chip AD9850 is kept stable;
the voltage-dividing bias amplifying circuit is arranged to amplify the power of the sine alternating current signal output by the sine wave generating circuit, stabilize the static working point of the field effect transistor Q1 and eliminate the zero drift of the field effect transistor Q1, so that the stability of the output sine alternating current signal is further improved;
by arranging the isolation circuit, the coupling between the sinusoidal alternating current signal output by the voltage division type bias amplifying circuit and the power supply and the ground is eliminated, the direct current signal is isolated, the sinusoidal alternating current signal is prevented from sudden change caused by the coupling between the power supply and the ground, and the stability of the sinusoidal alternating current signal output after being processed by the voltage division type bias amplifying circuit is further improved;
by arranging the T-shaped matching circuit, on one hand, the output impedance of the voltage division type bias amplifying circuit is matched with the impedance of the voltage transformer, so that the power loss of the sinusoidal alternating current signal output by the voltage division type bias amplifying circuit is reduced, and the stability of the output sinusoidal alternating current signal is improved; and on the other hand, the voltage-dividing bias amplifying circuit is used for tuning, so that the sinusoidal alternating current signal current output by the voltage-dividing bias amplifying circuit is in phase with the voltage, the reactive loss of the voltage-dividing bias amplifying circuit is further reduced, and the power and the stability of the sinusoidal alternating current signal output by the voltage-dividing bias amplifying circuit are improved.
The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. The utility model provides a fast ground connection downlead conduction tester of test speed, its includes CPU chip, voltage transformer, voltage detection module and sine wave generating circuit, its characterized in that: the power supply, the voltage division type bias amplifying circuit and the T-shaped matching circuit are also included;
the output end of the sine wave generating circuit is electrically connected with the input end of the voltage-dividing bias amplifying circuit, the power supply is electrically connected with the power supply end of the voltage-dividing bias amplifying circuit, the output end of the voltage-dividing bias amplifying circuit is electrically connected with the input end of the T-shaped matching circuit, the output end of the T-shaped matching circuit is respectively electrically connected with one end of the grounding down lead and the input end of the voltage detection module through the voltage transformer, the output end of the voltage detection module is electrically connected with the analog input end of the CPU chip, and the other end of the grounding down lead outputs a current signal.
2. The conduction tester of the ground down lead with high test speed according to claim 1, characterized in that: also includes an isolation circuit;
the power supply is electrically connected with the input end of the isolation circuit, and the output end of the isolation circuit is electrically connected with the output end of the voltage division type bias amplifying circuit.
3. The conduction tester of the ground down lead with high testing speed of claim 2, characterized in that: the voltage division type bias amplifying circuit comprises resistors R1-R3, a capacitor C1, a capacitor C2 and a field effect transistor Q1;
the output end of the sine wave generating circuit is electrically connected with one end of a resistor R1, one end of a resistor R2, one end of a resistor R3 and the grid of a field-effect tube Q1 through a capacitor C1 respectively, the other end of the resistor R1 is electrically connected with a power supply, the other end of the resistor R2 is grounded, the other end of the resistor R3 is grounded through a capacitor C2, the source of a field-effect tube Q1 is grounded, and the drain of the field-effect tube Q1 is electrically connected with the output end of the isolating circuit and the input end of the T-shaped matching circuit respectively.
4. The conduction tester of the ground down lead with high testing speed of claim 3, characterized in that: the isolation circuit comprises a polar capacitor C3 and a radio frequency choke RFC;
the power supply is respectively electrically connected with one end of the radio frequency choke RFC and the anode of the polar capacitor C3, the cathode of the polar capacitor C3 is grounded, and the other end of the radio frequency choke RFC is electrically connected with the drain electrode of the field effect transistor Q1.
5. The conduction tester of the ground down lead with high testing speed of claim 3, characterized in that: the T-type matching circuit comprises an inductor L1, a variable capacitor C4 and a variable capacitor C5;
the drain of the field effect transistor Q1 is electrically connected to one end of the variable capacitor C4 and one end of the variable capacitor C5 through the inductor L1, respectively, the other end of the variable capacitor C5 is grounded, and the other end of the variable capacitor C4 is electrically connected to the input end of the voltage transformer.
6. The conduction tester of the ground down lead with high test speed according to claim 1, characterized in that: the sine wave generating circuit comprises a signal generating chip AD9850 and a photoelectric isolation circuit;
the RF _ OUT end of the signal generating chip AD9850 is electrically connected with the input end of the voltage division type bias amplifying circuit through the photoelectric isolation circuit.
7. The conduction tester of the ground down lead with high testing speed of claim 6, characterized in that: the photoelectric isolation circuit comprises a capacitor C6, a capacitor C7, resistors R13-R15, a first operational amplifier LM741, a second operational amplifier LM741 and a linear optocoupler HCNR 201;
the RF _ OUT terminal of the signal generating chip AD9850 is electrically connected to the inverting input terminal of the first operational amplifier LM741 and the third pin of the linear optocoupler HCNR201 through a resistor R13, the non-inverting input end of the first operational amplifier LM741 is grounded, the capacitor C6 is connected in parallel between the inverting input end of the first operational amplifier LM741 and the output end thereof, the output end of the first operational amplifier LM741 is electrically connected with the first pin of the linear optical coupler HCNR201 through the resistor R15, the fourth pin and the fifth pin of the linear optical coupler HCNR201 are grounded, the sixth pin of the linear optical coupler HCNR201 is electrically connected with the inverting input end of the second operational amplifier LM741, the non-inverting input end of the second operational amplifier LM741 is grounded, the resistor R14 is connected in parallel between the inverting input end of the second operational amplifier LM741 and the output end thereof, the capacitor C7 is connected in parallel at two ends of the resistor R14, and the output end of the second operational amplifier LM741 is electrically connected with the input end of the voltage-dividing bias amplifying circuit.
8. The conduction tester of the ground down lead with high test speed according to claim 1, characterized in that: the current transformer and the current detection module are also included;
the current transformer collects current on the grounding down lead and inputs a current signal corresponding to the current to the input end of the current detection module, and the output end of the current detection module is electrically connected with the analog input end of the CPU chip.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114111850A (en) * | 2021-11-25 | 2022-03-01 | 荣成歌尔微电子有限公司 | Microphone, electronic equipment, coupling capacitance type sensor and signal processing method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114111850A (en) * | 2021-11-25 | 2022-03-01 | 荣成歌尔微电子有限公司 | Microphone, electronic equipment, coupling capacitance type sensor and signal processing method thereof |
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