Frequency conversion grounding impedance tester
By designing an overvoltage protection circuit and a charging protection circuit in the variable frequency ground impedance tester, the problems of unstable power supply and complex protection circuit when the battery is about to run out are solved, thus achieving effective protection for the equipment and extending its service life.
Patent Information
- Application Number
- CN202422537938.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2025-09-12
- Estimated Expiration
- 2034-10-21
AI Technical Summary
Existing variable frequency ground impedance testers have unstable power supply when the battery is about to run out, and the protection circuit structure is complex, resulting in a shortened equipment life and high maintenance costs.
A variable-frequency ground impedance tester was designed, which includes both an overvoltage protection circuit and a charging protection circuit. The overvoltage protection circuit uses a combination of a PMOS transistor and a voltage regulator to promptly cut off unstable voltage output; the charging protection circuit uses an NMOS transistor and a protection chip to prevent overcharging.
It effectively protects the tester and battery, avoids damage to the equipment caused by unstable voltage, simplifies the protection circuit structure, reduces maintenance costs, and extends the service life of the equipment.
Smart Images
Figure CN223333086U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of impedance testing, in particular to a variable frequency grounding impedance tester. Background Art
[0002] A variable frequency ground impedance tester generally refers to a hardware and software system used to accurately measure ground impedance, ground resistance, ground reactance, surface potential gradient of a large grounding grid, contact potential difference, contact voltage, step potential difference, step voltage, transfer potential, ground lead conduction resistance, soil resistivity and other ground characteristic parameters. Existing variable frequency ground impedance testers usually have two power supply modes, one is to directly plug into an AC power source, and the other is to use a backup battery for power supply in the absence of an external power supply. When using a backup battery for power supply, the power supply stability is insufficient when the battery is about to run out, which can easily cause problems when used under an unstable power supply, shortening the service life, and also having an adverse effect on the battery. The existing protection circuit has a complex circuit structure and high repair and maintenance costs. Utility Model Content
[0003] In response to the shortcomings of the existing technology, the utility model provides a variable frequency ground impedance tester, which solves the technical problems of unstable power supply before the battery is exhausted and the complex protection circuit structure in the existing technology, and achieves the purpose of protecting the tester and battery by using a simple protection circuit during use.
[0004] In order to solve the above technical problems, the utility model provides the following technical solutions: a variable frequency ground impedance tester, comprising a battery and a tester for measuring impedance, an overvoltage protection circuit is connected between the battery and the tester, and a charging circuit is connected to the charging side of the battery;
[0005] The overvoltage protection circuit includes a fixed resistor R7, a fixed resistor R9, a voltage regulator D1 and a PMOS transistor Q2 connected in series in sequence, the fixed resistor R9 is connected to the gate of the PMOS transistor Q2, the source of the PMOS transistor Q2 is connected in parallel with the fixed resistor R7, a fixed resistor R8 is connected in parallel between the voltage regulator D1 and the fixed resistor R7, the fixed resistor R8 is connected in series with a transistor Q3 and the fixed resistor R8 is connected to the base of the transistor Q3, the emitter of the transistor Q3 is connected in parallel with the fixed resistor R7, the collector of the transistor Q3 is connected in parallel with the fixed resistor R9, a capacitor C7 is connected in parallel on the side of the voltage regulator D1 and the fixed resistor R7, and the drain of the PMOS transistor Q2 provides an output voltage to the tester.
[0006] Preferably, the charging circuit includes a rectifier circuit for rectifying the charging current, a microprocessor module for filtering the charging current, and a charging protection circuit for protecting the battery in a charging state.
[0007] Preferably, the rectifier circuit includes a 220V AC power input, a transformer and a bridge rectifier connected in parallel with the transformer, a fixed resistor R1 is connected in series to the a-end of the bridge rectifier, a capacitor C1 and a fixed resistor Ra are connected in parallel between the a-end and the b-end of the bridge rectifier, and the fixed resistor R1 and the fixed resistor Ra are directly connected to the DCR# port of the microprocessor module.
[0008] Preferably, the DCR# port of the microprocessor module filters the charging current through a parallel capacitor C5, the V3 port of the microprocessor module transmits the processing current to the charging protection circuit through a fixed resistor R6 and a parallel capacitor C6, the VCC port of the microprocessor module is connected to a 12V external power supply, and the GND port of the microprocessor module is grounded.
[0009] Preferably, the charging protection circuit includes fixed resistors R2, R3 and R4 connected in series in sequence, a capacitor C3 is connected in parallel between the fixed resistors R2 and R3, a protection chip Z is connected in parallel between the fixed resistors R3 and R4, the REF port of the protection chip Z receives the processing current through the fixed resistors R3 and R4, the AN port of the protection chip Z is grounded, the fixed resistor R4 is connected to the negative pole of the battery, the CAT port of the protection chip Z is connected to a fixed resistor R5, the fixed resistor R5 is connected in parallel with an NMOS tube Q1, the gate of the NMOS tube Q1 is connected in parallel to one end of the fixed resistor R5, the source of the NMOS tube Q1 is connected in parallel to the other end of the fixed resistor R5, the drain of the NMOS tube Q1 is connected to the positive pole of the battery, and the capacitor C4 is connected in parallel between the positive and negative poles of the battery.
[0010] Preferably, the model of the microprocessor module is STM32F4, and the model of the protection chip Z is TL431.
[0011] By means of the above technical solution, the utility model provides a variable frequency ground impedance tester, which has at least the following beneficial effects:
[0012] 1. The utility model uses the overvoltage protection circuit to cut off the voltage output in time when the battery is about to be exhausted and the voltage output is unstable, thereby protecting the battery and the tester from being affected by the unstable voltage. At the same time, the structure of the overvoltage protection circuit is simplified, which can reduce costs, make repair and maintenance more convenient, and better protect the tester and battery, thereby extending their service life.
[0013] 2. The utility model can protect the battery during the charging process through the function of the charging circuit. At the same time, the use of the NMOS tube Q1 and the protection chip can better protect the battery and prevent overcharging problems. The charging current can be made more stable through capacitor filtering, thereby increasing the service life of the battery. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:
[0015] Figure 1 This is a circuit structure diagram of a variable frequency ground impedance tester of the utility model;
[0016] Figure 2 This is a circuit diagram of the rectifier circuit of the utility model;
[0017] Figure 3 This is a circuit diagram of the charging protection circuit of the utility model;
[0018] Figure 4 This is a circuit diagram of the overvoltage protection circuit of the utility model;
[0019] Figure 5 This is a circuit diagram of the microprocessor module of the present utility model.
[0020] In the figure: 1. Charging circuit; 11. Rectification circuit; 12. Microprocessor module; 13. Charging protection circuit; 2. Battery; 3. Overvoltage protection circuit; 4. Tester. DETAILED DESCRIPTION
[0021] To make the above-mentioned objectives, features, and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. This will enable a full understanding of how the present invention applies technical means to solve technical problems and achieve technical effects, and to implement the invention accordingly.
[0022] Due to the technical problems of unstable power supply before battery power is exhausted and complex protection circuit structure in the existing technology, please refer to Figure 1 - Figure 5This embodiment provides a variable frequency ground impedance tester that can protect the tester and battery using a simple protection circuit. The variable frequency ground impedance tester includes a battery 2 and a tester 4 for measuring impedance. An overvoltage protection circuit 3 is connected between the battery 2 and the tester 4. The charging side of the battery 2 is connected to a charging circuit 1. The overvoltage protection circuit 3 includes a fixed resistor R7, a fixed resistor R9, a voltage regulator D1, and a PMOS tube Q2 connected in series. The fixed resistor R9 The gate of the PMOS tube Q2 is connected, the source of the PMOS tube Q2 is connected in parallel with the fixed resistor R7, a fixed resistor R8 is connected in parallel between the voltage regulator tube D1 and the fixed resistor R7, the fixed resistor R8 is connected in series with the transistor Q3 and the fixed resistor R8 is connected to the base of the transistor Q3, the emitter of the transistor Q3 is connected in parallel with the fixed resistor R7, the collector of the transistor Q3 is connected in parallel with the fixed resistor R9, the capacitor C7 is connected in parallel on the side of the voltage regulator tube D1 and the fixed resistor R7, and the drain of the PMOS tube Q2 provides the output voltage to the tester 4.
[0023] When the battery 2 is used to power the tester 4, the present invention controls the power supply of the battery 2 to the tester 4 through the PMOS tube Q2, and cooperates with the fixed resistor R7, the fixed resistor R9, the voltage regulator D1 and the transistor Q3 to detect abnormal voltage. When the power supply voltage is less than 5.1V, for example, the power supply voltage is 5V, the voltage regulator tube conduction voltage is 5.1V, so the voltage regulator tube D1 is not turned on, so the transistor Q3 will not be turned on, and then the gate of the PMOS tube Q2 will be pulled to 0V by the fixed resistor R9, the PMOS tube Q2 is turned on, and the output voltage is 5V. If the power supply voltage is about 5.3V, the voltage regulator tube D1 is turned on. The voltage regulator tube D1 is turned on, the emitter voltage of the transistor Q3 is 5.3V, and the base voltage is 5.1V, so the transistor Q3 still will not be turned on. The PMOS tube Q2 will normally conduct and the output voltage is about 5.3V. If the supply voltage is 5.9V, the turn-on voltage of the voltage regulator tube D1 is 5.1V, so it is turned on, and the voltage drop across the fixed resistor R7 is 0.8V. The emitter voltage of the transistor is 5.9V and the base voltage is 5.3V. Therefore, the transistor Q3 is turned on, and the gate voltage of the PMOS tube Q2 becomes 5.9V. Therefore, the PMOS tube Q2 is not turned on, and there will be no output voltage. Through the function of the overvoltage protection circuit, when the battery power is about to be exhausted and the voltage output is unstable, the voltage output can be cut off in time to protect the battery and the tester from being affected by the unstable voltage. At the same time, the structure of the overvoltage protection circuit is more simplified, which can reduce costs and make repair and maintenance more convenient. The tester and battery can be better protected and their service life is extended.
[0024] During the charging process, the charging voltage is prone to fluctuations, and it is easy to overcharge the battery, resulting in a reduction in battery life and service life. Please refer to Figure 2- Figure 4 , this problem is not solved. This embodiment provides a charging circuit 1 including a rectifier circuit 11 for rectifying the charging current, a microprocessor module 12 for filtering the charging current, and a charging protection circuit 13 for protecting the battery 2 in the charging state. The rectifier circuit 11 includes a 220V AC input, a transformer, and a bridge rectifier connected in parallel with the transformer. A fixed resistor R1 is connected in series to the a-end of the bridge rectifier. A capacitor C1 and a fixed resistor Ra are connected in parallel between the a-end and the b-end of the bridge rectifier. The fixed resistor R1 and the fixed resistor Ra are directly connected to the DCR# port of the microprocessor module 12. The DCR# port of the microprocessor module 12 filters the charging current through the parallel capacitor C5. The V3 port of the microprocessor module 12 transmits the processing current to the charging protection circuit 13 through the fixed resistor R6 and the parallel capacitor C6. The VCC port of the microprocessor module 12 is connected to a 12V external power supply. The GND port of the microprocessor module 12 is grounded. The charging protection circuit 13 includes fixed resistors R2, R3, and R4 connected in series in sequence. A capacitor C3 is connected in parallel between the fixed resistors R2 and R3. A protection chip Z is connected in parallel between the fixed resistors R3 and R4. The REF port of the protection chip Z receives the processing current through the fixed resistors R3 and R4. The AN port of the protection chip Z is grounded. The fixed resistor R4 is connected to the negative electrode of the battery. The CAT port of the protection chip Z is connected to a fixed resistor R5. The fixed resistor R5 is connected in parallel with an NMOS transistor Q1. The gate of the NMOS transistor Q1 is connected in parallel to one end of the fixed resistor R5, the source of the NMOS transistor Q1 is connected in parallel to the other end of the fixed resistor R5, the drain of the NMOS transistor Q1 is connected to the positive electrode of the battery, and the capacitor C4 is connected in parallel between the positive and negative electrodes of the battery. The model of the microprocessor module 12 is STM32F4, and the model of the protection chip Z is TL431.
[0025] The utility model uses a bridge rectifier to rectify the current, making the charging current more stable, and then outputs the charging current to the microprocessor module 12. The microprocessor module 12 filters the charging current and repairs the problems such as missing waveform in the charging current and outputs the processed current. After the charging protection circuit receives the processed current, the NMOS tube Q1 is turned on to charge the battery 2. When the voltage of the battery 2 slowly rises to the rated charging voltage, such as 14.8V, the REF terminal voltage of the protection chip Z will reach 2.5V. At this time, the CAT and AN ports of the protection chip Z will be turned on, the gate of the NMOS tube Q1 becomes a low potential, and the NMOS tube Q1 is turned off, thereby completing the charging and protecting the battery. Through the action of the charging circuit, the battery can be charged and protected during the charging process. At the same time, the combined action of the NMOS tube Q1 and the protection chip can better protect the battery and prevent overcharging problems. The charging current can be made more stable through capacitor filtering, thereby increasing the service life of the battery.
[0026] The above embodiments provide a detailed introduction to the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method and core idea of the present invention. At the same time, for those skilled in the art, according to the idea of the present invention, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.
Claims
1. A variable frequency ground impedance tester, comprising a battery (2) and a tester (4) for measuring impedance, characterized in that: An overvoltage protection circuit (3) is connected between the battery (2) and the tester (4), and a charging circuit (1) is connected to the charging side of the battery (2); The overvoltage protection circuit (3) comprises a fixed resistor R7, a fixed resistor R9, a voltage regulator D1 and a PMOS tube Q2 connected in series in sequence, the fixed resistor R9 is connected to the gate of the PMOS tube Q2, the source of the PMOS tube Q2 is connected in parallel with the fixed resistor R7, a fixed resistor R8 is connected in parallel between the voltage regulator D1 and the fixed resistor R7, the fixed resistor R8 is connected in series with a transistor Q3 and the fixed resistor R8 is connected to the base of the transistor Q3, the emitter of the transistor Q3 is connected in parallel with the fixed resistor R7, the collector of the transistor Q3 is connected in parallel with the fixed resistor R9, a capacitor C7 is connected in parallel on the side of the voltage regulator D1 and the fixed resistor R7, and the drain of the PMOS tube Q2 provides an output voltage to the tester (4).
2. A variable frequency ground impedance tester according to claim 1, characterized in that: The charging circuit (1) comprises a rectifier circuit (11) for rectifying the charging current, a microprocessor module (12) for filtering the charging current, and a charging protection circuit (13) for protecting the battery (2) in a charging state.
3. A variable frequency ground impedance tester according to claim 2, characterized in that: The rectifier circuit (11) includes a 220V AC power input, a transformer, and a bridge rectifier connected in parallel with the transformer. A fixed resistor R1 is connected in series to the a-end of the bridge rectifier. A capacitor C1 and a fixed resistor Ra are connected in parallel between the a-end and the b-end of the bridge rectifier. The fixed resistor R1 and the fixed resistor Ra are directly connected to the DCR# port of the microprocessor module (12).
4. A variable frequency ground impedance tester according to claim 2, characterized in that: The DCR# port of the microprocessor module (12) filters the charging current through a parallel capacitor C5, the V3 port of the microprocessor module (12) transmits the processing current to the charging protection circuit (13) through a fixed resistor R6 and a parallel capacitor C6, the VCC port of the microprocessor module (12) is connected to a 12V external power supply, and the GND port of the microprocessor module (12) is grounded.
5. The variable frequency ground impedance tester according to claim 2, characterized in that: The charging protection circuit (13) comprises fixed resistors R2, R3 and R4 connected in series in sequence, a capacitor C3 is connected in parallel between the fixed resistors R2 and R3, a protection chip Z is connected in parallel between the fixed resistors R3 and R4, a REF port of the protection chip Z receives a processing current through the fixed resistors R3 and R4, an AN port of the protection chip Z is grounded, the fixed resistor R4 is connected to the negative electrode of the battery, a CAT port of the protection chip Z is connected to a fixed resistor R5, the fixed resistor R5 is connected in parallel to an NMOS transistor Q1, a gate of the NMOS transistor Q1 is connected in parallel to one end of the fixed resistor R5, a source of the NMOS transistor Q1 is connected in parallel to the other end of the fixed resistor R5, a drain of the NMOS transistor Q1 is connected to the positive electrode of the battery, and a capacitor C4 is connected in parallel between the positive and negative electrodes of the battery.
6. The variable frequency ground impedance tester according to claim 5, characterized in that: The model of the microprocessor module (12) is STM32F4, and the model of the protection chip Z is TL431.