CN216816907U - Leakage current detection prompting circuit - Google Patents
Leakage current detection prompting circuit Download PDFInfo
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- CN216816907U CN216816907U CN202122441850.3U CN202122441850U CN216816907U CN 216816907 U CN216816907 U CN 216816907U CN 202122441850 U CN202122441850 U CN 202122441850U CN 216816907 U CN216816907 U CN 216816907U
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Abstract
The utility model discloses a leakage current detection prompting circuit, which comprises a detection circuit 1, a detection circuit 2, a differential amplification circuit and a prompting circuit, wherein the detection circuit comprises a first detection circuit, a second detection circuit and a third detection circuit; and the positive and negative loops of the input end of the switching power supply are respectively connected with sampling resistors R1 and R2; the detection circuits 1 and 2 are respectively connected with two ends of the sampling resistors R1 and R2, and are used for detecting voltages at two ends of the sampling resistors R1 and R2, generating voltage signals 1 and 2, and respectively outputting the voltage signals to two input ends of the differential amplification circuit; the differential amplifying circuit is connected between the detection circuits 1 and 2 and the prompting circuit and is used for comparing the voltage signals 1 and 2 and outputting the difference value to the input end of the voltage prompting circuit after amplifying; the prompting circuit is used for giving out a leakage prompt when the difference value between the voltage signals 1 and 2 exceeds a certain threshold value. Therefore, whether the power supply leaks electricity or not can be measured quickly, accurately and efficiently.
Description
Technical Field
The utility model relates to a detection circuit, in particular to a leakage current detection prompt circuit, and belongs to the technical field of electrical switches.
Background
Switching power supplies are a common type of power conversion device and can be found in almost any electrical device. It is also one of the most vulnerable components of electrical equipment to failure. When the electric equipment has faults such as circuit damage or skin breaking, the equipment shell is electrified, once a person touches the shell, the danger of electric shock can occur, and the electric equipment can be damaged due to overlarge leakage current.
Most of the switch power supplies in the current market only have the function of a switch circuit, and have no function of detecting whether electric leakage exists. In the prior art, a leakage current transformer is used for detecting leakage current, and the leakage current is detected by collecting the magnitude of the leakage current and adding an operational amplifier and a filter; also there is the device that is used for specially detecting this kind of condition, needs the user to use the device by oneself and detects whether electric leakage, but all the function is miscellaneous, the operation is not convenient, purchase cost is higher, can't the scale use widely.
SUMMERY OF THE UTILITY MODEL
In view of the above existing technical problems, the present invention provides a leakage current detection prompting circuit, which can prompt a user to know that the leakage current is too large as soon as possible through the prompting of an LED lamp when the leakage current reaches a certain value.
In order to achieve the above object, the present invention provides a leakage current detection prompting circuit, which includes a detection circuit 1, a detection circuit 2, a differential amplification circuit and a prompting circuit; and the positive and negative loops of the input end of the switching power supply are respectively connected with sampling resistors R1 and R2;
the detection circuits 1 and 2 are respectively connected with two ends of the sampling resistors R1 and R2, and are used for detecting voltages at two ends of the sampling resistors R1 and R2, generating voltage signals 1 and 2, and respectively outputting the voltage signals to two input ends of the differential amplification circuit;
the differential amplification circuit is connected between the detection circuits 1 and 2 and the prompting circuit, and is used for comparing the voltage signals 1 and 2 and outputting the difference value to the input end of the voltage prompting circuit after amplifying;
the prompting circuit is used for giving out an electric leakage prompt when the difference value between the voltage signals 1 and 2 exceeds a certain threshold value.
Further, the detection circuit 1, 2 comprises a microcontroller U4 and a microcontroller U4';
the positive potential end and the negative potential end of the resistor R1 are respectively connected with the positive input end and the negative input end of the microcontroller U4, and the output end of the microcontroller U4 is connected with one input end of the differential amplification circuit; the positive potential end and the negative potential end of the resistor R2 are respectively connected with the positive input end and the negative input end of the microcontroller U4 ', and the output end of the microcontroller U4' is connected with the other input end of the differential amplification circuit.
Furthermore, the microcontroller U4 and the microcontroller U4' employ INA181a1 series chips.
Further, the differential amplification circuit comprises an operational amplifier U3 and resistors R5-R7;
the output ends of the detection circuits 1 and 2 are respectively connected with the inverting input end and the inverting input end of the operational amplifier U3, the positive power supply end of the operational amplifier U3 is grounded, the negative power supply end is grounded, and the output end is connected with the input end of the prompt circuit.
Furthermore, the output end resistor R10 of the operational amplifier U3 is connected with the input end of the prompting circuit.
Furthermore, the positive power terminal of the operational amplifier U3 is connected to ground via a capacitor C6.
Furthermore, the prompting circuit comprises a voltage stabilizing diode Z1, a resistor R9, a triode Q2 and a light emitting diode D2;
the output end of the differential amplification circuit is connected with the cathode of a voltage stabilizing diode Z1, and the anode of the voltage stabilizing diode Z1 is grounded through a resistor R9; the common end of the voltage-stabilizing diode Z1 and the resistor R9 is connected with the base electrode of the triode Q2; the emitter of the triode Q2 is grounded; the collector of the transistor Q2 is connected to the cathode of the led D2, and the anode of the led D2 is connected to the Vcc terminal of the switching power supply.
Furthermore, the emitter of the transistor Q2 is grounded via a resistor R8.
Furthermore, the cathode or the anode of the led D2 is connected in series with a buzzer.
According to the technical scheme, the method utilizes kirchhoff's law to measure the current of the positive loop and the current of the negative loop of the input end of the switching power supply respectively, and if the current of the positive pole and the current of the negative pole in the switching power supply are not equal, the current leakage exists at the rear stage of the measuring point. Therefore, the magnitude of the leakage current can be obtained by comparing the current difference between the anode and the cathode of the switching power supply. When the current difference reaches a certain value, the conduction voltage of the Q1 triode is switched on, and the light emitting diode D2 emits light to indicate the prompt.
The utility model has the following beneficial effects: when the switch power supply generates electric leakage, the electric leakage detection prompting circuit is conducted, and an alarm is given to a user through the light-emitting diode and the buzzer.
Compared with the prior art, the utility model has the following technical advantages:
1. the leakage inspection is performed without manual operation, and the inspection efficiency is improved.
2. The method can realize quick, accurate and efficient measurement of whether the power supply leaks electricity or not.
2. Convenient operation, low cost and wide application range.
Drawings
FIG. 1 is a schematic diagram of the connection of the present invention to a switching converter module;
FIG. 2 is a schematic diagram of a conventional switching conversion circuit topology BUCK;
fig. 3 is a circuit diagram of the present invention.
Detailed Description
Preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While the preferred embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
As shown in figure 1, the circuit of the utility model is connected with a switch converter module, the magnitudes of currents on positive and negative loops of an input end of a switch power supply are respectively detected by using kirchhoff's law, and if the currents of the positive pole and the negative pole of the switch power supply are not equal, the current leakage exists at the rear stage of a detection point. Therefore, the magnitude of the leakage current can be obtained by comparing the current difference between the anode and the cathode of the switching power supply.
As shown in fig. 2, a switching power supply of BUCK topology controlled by a single voltage ring is taken as an example. The positive electrode of the input end of the switching power supply is connected with one end of a resistor R1, the other end of the resistor R1 is connected with the collector of an NPN type triode Q1, the emitter of the NPN type triode Q1 is connected with one end of an inductor L1, and the other end of the inductor L1 is connected with the positive electrode of a load; the negative pole of the input end of the switch power supply is connected with one end of the resistor R2, and the other end of the resistor R2 is connected with the negative pole of the load. Two ends of the capacitor C1 are respectively connected in parallel with the anode and the cathode of the load. The cathode of the light emitting diode D1 is connected to the emitter of the NPN transistor Q1, and the anode thereof is connected to the other end of the resistor R2. The base of the NPN type triode Q1 is connected with the driving module, the driving module is connected with the output end of the operational amplifier U2, the non-inverting input end of the operational amplifier U2 is connected with the output end of the operational amplifier U1, and the inverting input end of the operational amplifier U1 is connected with one end of the voltage stabilizing diode Z1 and connected with the common end of the resistors R3 and R4. The anode of the load is grounded through resistors R3 and R4.
In the circuit, the NPN type triode Q1 can drive the light-emitting diode D1 to emit light; the operational amplifier U1 is connected with a set voltage for controlling the output size (generally between 0-3.3V); the operational amplifier U2 is a PWM generating module and is reversely connected with a carrier signal of a sawtooth wave; the load is simply an analog power supply load.
In order to detect the current magnitude of the positive and negative loops of the input end of the switching power supply, the resistors R1 and R2 are sampling resistors. The positive potential end of the resistor R1 is a detection point 1+, and the negative potential end is a detection point 1-; the positive potential end of the resistor R2 is a detection point 2-, the negative potential end is a detection point 2+, and the 4 detection points are directly connected with the two detection circuits. Because the resistance of the sampling resistor is generally very small, and the voltage values at the two ends of the resistors R1 and R2 are also relatively small, the utility model not only needs the detection circuit to collect the voltages at the two ends of the resistors R1 and R2, but also needs the differential amplification circuit to amplify the difference value of the two voltages, and starts the prompt circuit under the condition of relatively large difference value.
The utility model comprises a detection circuit 1, a detection circuit 2, a differential amplification circuit and a prompt circuit; the detection circuits 1 and 2 are respectively connected with two ends of the sampling resistors R1 and R2, and are used for detecting voltages at two ends of the sampling resistors R1 and R2, generating voltage signals 1 and 2, and respectively outputting the voltage signals to two input ends of the differential amplification circuit; the differential amplification circuit is connected between the detection circuits 1 and 2 and the prompting circuit, and is used for comparing the voltage signals 1 and 2 and outputting the difference value to the input end of the voltage prompting circuit after amplifying; the prompting circuit is used for giving out an electric leakage prompt when the difference value between the voltage signals 1 and 2 exceeds a certain threshold value.
As shown in fig. 3, in practice, the detection circuit 1, 2 includes a microcontroller U4 and a microcontroller U4'; the differential amplification circuit comprises an operational amplifier U3, a capacitor C6 and resistors R5-R7; the prompting circuit comprises a triode Q2, a voltage stabilizing diode Z1, a light emitting diode D2 and resistors R8-R10; the specific circuit connection relationship is as follows.
The microcontroller U4, U4', an operational amplifier U3, a triode Q2, a Zener diode Z1, a capacitor C6, a light-emitting diode D2 and resistors R5-R10; in implementation, the microcontrollers U4 and U4' adopt INA181A1 series chips.
The detection point 1+ and the detection point 1-are respectively connected with the positive input end and the negative input end of the microcontroller U4, and the output end of the microcontroller U4 is connected with the non-inverting input end of the operational amplifier U3 through a resistor R6;
the detection point 2+ and the detection point 2-are respectively connected with the positive input end and the negative input end of the microcontroller U4 ', and the output end of the microcontroller U4' is connected with the inverting input end of the operational amplifier U3 through a resistor R5;
the positive power supply end of the operational amplifier U3 is grounded through a capacitor C6, the negative power supply end is grounded, the output end is connected with the cathode of a voltage stabilizing diode Z1 through a resistor R10, and the anode of the voltage stabilizing diode Z1 is grounded through a resistor R9;
the VCC end of the switch power supply is connected with the anode of the LED D2, the cathode of the LED D2 is connected with the collector of the triode Q2, the emitter of the triode Q2 is grounded through a resistor R8, and the base of the triode Q2 is connected with the common end of the Zener diode Z1 and the resistor R9.
The working principle of the circuit is as follows: the microcontroller U4 collects voltages at two ends of the resistor R1 through a detection point 1+ and a detection point 1, the microcontroller U4 'collects voltages at two ends of the resistor R2 through a detection point 2+ and a detection point 2, then output ends of the microcontrollers U4 and U4' are respectively connected to a non-inverting input end and an inverting input end of the operational amplifier U3, and the operational amplifier U3 is used for comparing voltage values output by the two microcontrollers and outputting a difference value after amplifying the difference value. The zener diode Z1 and the resistor R9 divide the output voltage of the operational amplifier U3. When the regulated voltage of the zener diode Z1 is reached, the output voltage is distributed to the resistor R9, and when the voltage across the resistor R9 reaches the conduction voltage of the NPN transistor Q2, the NPN transistor Q2 is turned on, and the light emitting diode D2 lights up. In addition, the diode D2 may be connected in series with a buzzer to sound an alarm.
The output voltage V4 of the microcontroller U4, the output voltage V4 'of the microcontroller U4' and the output voltage V3 of the operational amplifier U3 are calculated as follows:
V4＝(Vdetection 1+-VDetection 1-)*A
V4′＝(VDetection 2+-VDetection 2-)*A
In the formula, V4 is a multiple of the voltage on the pick-up R1, i.e., the output voltage of U4. A is the amplification factor of the microcontroller U4, U4', and is generally 20 times, 50 times, 100 times, 200 times.
In summary, if there is a leakage current in the rear stage of the detection point in the switching power supply, the values of the current and the voltage collected by the resistors R1 and R2 will be different. If the voltage values of the resistors R1 and R2 are greatly different, the base voltage of the NPN type triode Q1 is greatly improved, the NPN type triode Q1 is conducted, and the light-emitting diode D2 is lightened, so that the situation of leakage current is prompted; if the voltage values of the resistors R1 and R2 are not different, the output voltage of the operational amplifier U3 does not reach the on voltage (generally 0.7V) of the transistor Q1, and the light emitting diode D2 will not emit light.
The utility model can realize the effects of quickly, accurately and efficiently measuring whether the power supply generates electric leakage or not, has convenient operation and low cost and is suitable for large-scale popularization and use.
Having described embodiments of the present disclosure, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (9)
1. A leakage current detection prompting circuit is characterized by comprising a detection circuit 1, a detection circuit 2, a differential amplification circuit and a prompting circuit; and the positive and negative loops of the input end of the switching power supply are respectively connected with sampling resistors R1 and R2;
the detection circuits 1 and 2 are respectively connected with two ends of the sampling resistors R1 and R2, and are used for detecting voltages at two ends of the sampling resistors R1 and R2, generating voltage signals 1 and 2, and respectively outputting the voltage signals to two input ends of the differential amplification circuit;
the differential amplification circuit is connected between the detection circuits 1 and 2 and the prompting circuit, and is used for comparing the voltage signals 1 and 2 and outputting the difference value to the input end of the voltage prompting circuit after amplifying;
the prompting circuit is used for giving out an electric leakage prompt when the difference value between the voltage signals 1 and 2 exceeds a certain threshold value.
2. A leakage current detection prompting circuit according to claim 1, characterized in that the detection circuits 1, 2 comprise a microcontroller U4 and a microcontroller U4';
the positive potential end and the negative potential end of the resistor R1 are respectively connected with the positive input end and the negative input end of the microcontroller U4, and the output end of the microcontroller U4 is connected with one input end of the differential amplification circuit; the positive potential end and the negative potential end of the resistor R2 are respectively connected with the positive input end and the negative input end of the microcontroller U4 ', and the output end of the microcontroller U4' is connected with the other input end of the differential amplification circuit.
3. The leakage current detection prompt circuit as claimed in claim 2, wherein the microcontroller U4 and the microcontroller U4' employ INA181a1 series chips.
4. A leakage current detection prompt circuit according to claim 1, wherein the differential amplifier circuit comprises an operational amplifier U3 and resistors R5-R7;
the output ends of the detection circuits 1 and 2 are respectively connected with the inverting input end and the inverting input end of the operational amplifier U3, the positive power supply end of the operational amplifier U3 is grounded, the negative power supply end is grounded, and the output end is connected with the input end of the prompt circuit.
5. A leakage current detection prompt circuit as claimed in claim 4, wherein an output resistor R10 of the operational amplifier U3 is connected to an input terminal of the prompt circuit.
6. The leakage current detection prompt circuit of claim 4, wherein the positive power terminal of the operational amplifier U3 is connected to ground via a capacitor C6.
7. A leakage current detection prompt circuit according to any one of claims 1-6, wherein the prompt circuit comprises a Zener diode Z1, a resistor R9, a transistor Q2, and a light emitting diode D2;
the output end of the differential amplification circuit is connected with the cathode of a voltage stabilizing diode Z1, and the anode of the voltage stabilizing diode Z1 is grounded through a resistor R9; the common end of the voltage-stabilizing diode Z1 and the resistor R9 is connected with the base electrode of the triode Q2; the emitter of the triode Q2 is grounded; the collector of the transistor Q2 is connected to the cathode of the led D2, and the anode of the led D2 is connected to the Vcc terminal of the switching power supply.
8. The leakage current detection and prompting circuit of claim 7, wherein an emitter of the transistor Q2 is grounded via a resistor R8.
9. A leakage current detection and alarm circuit according to claim 7, wherein a buzzer is connected in series with a cathode or an anode of said light emitting diode D2.
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| CN202122441850.3U CN216816907U (en) | 2021-10-11 | 2021-10-11 | Leakage current detection prompting circuit |
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| CN202122441850.3U CN216816907U (en) | 2021-10-11 | 2021-10-11 | Leakage current detection prompting circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024022030A1 (en) * | 2022-07-28 | 2024-02-01 | 比亚迪股份有限公司 | Electric leakage detection device and method, and vehicle |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024022030A1 (en) * | 2022-07-28 | 2024-02-01 | 比亚迪股份有限公司 | Electric leakage detection device and method, and vehicle |
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