CN216748022U - Isolation detection circuit for isolating power supply - Google Patents
Isolation detection circuit for isolating power supply Download PDFInfo
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- CN216748022U CN216748022U CN202122909187.5U CN202122909187U CN216748022U CN 216748022 U CN216748022 U CN 216748022U CN 202122909187 U CN202122909187 U CN 202122909187U CN 216748022 U CN216748022 U CN 216748022U
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Abstract
An isolation detection circuit for isolating a power supply is provided, the isolation detection circuit comprising: the circuit comprises a first resistor, a second resistor, a third resistor and a fourth resistor, wherein one end of the first resistor is connected to the anode of the isolated power supply, the other end of the first resistor is connected to the second resistor, and the other end of the second resistor is connected to the ground; one end of the third resistor is connected to the ground, the other end of the third resistor is connected to the fourth resistor, and the other end of the fourth resistor is connected to the negative electrode of the isolated power supply; comparing the positive detection voltage measured across the second resistor with a preset positive reference voltage and comparing the negative detection voltage measured across the third resistor with a preset negative reference voltage to determine whether the isolation between the positive and negative electrodes of the isolated power supply is abnormal.
Description
Technical Field
The utility model relates to an keep apart electrical power generating system, especially relate to an keep apart detection circuitry for keeping apart power.
Background
The isolation detection circuit is used for detecting the isolation between the anode and the cathode of the isolation power supply. The current isolation detection circuit calculates the total current to be zero based on kirchhoff's law so as to respectively detect the impedance to the ground of the anode and the cathode of the isolation power supply. And confirming whether an isolation circuit of the isolation power supply is abnormal or not based on the magnitude of the impedance value to ground of the anode and the cathode of the isolation power supply and the relation between the impedance to ground of the anode and the cathode, and sending out an alarm signal when the isolation is abnormal. The current isolation detection circuit is interfered by noise due to the fact that current to the ground can cause inaccurate resistance measurement and easily causes false alarm.
SUMMERY OF THE UTILITY MODEL
According to the above-mentioned defect of prior art, the utility model provides an keep apart detection circuitry for keeping apart power, its characterized in that, keep apart detection circuitry includes: a first resistor, a second resistor, a third resistor, and a fourth resistor,
one end of the first resistor is connected to the anode of the isolated power supply, the other end of the first resistor is connected to the second resistor, and the other end of the second resistor is connected to the ground;
one end of the third resistor is connected to the ground, the other end of the third resistor is connected to the fourth resistor, and the other end of the fourth resistor is connected to the negative electrode of the isolated power supply;
comparing the positive detection voltage measured across the second resistor with a preset positive reference voltage and comparing the negative detection voltage measured across the third resistor with a preset negative reference voltage to determine whether the isolation between the positive and negative electrodes of the isolated power supply is abnormal.
Preferably, the first resistance is the same as the fourth resistance, and the second resistance is the same as the third resistance.
Preferably, the first resistance is greater than the second resistance, and the fourth resistance is greater than the third resistance.
Preferably, the first resistance is greater than 10 times the second resistance, and the fourth resistance is greater than 10 times the third resistance.
Preferably, the isolated power source is a lithium battery.
Preferably, when the positive detection voltage is greater than the positive reference voltage or the absolute value of the negative detection voltage is greater than the absolute value of the negative reference voltage, an isolation abnormality alarm signal is sent.
Preferably, the range of the positive reference voltage and the range of the negative reference voltage are calculated from a predetermined value of a positive impedance to ground of the isolated power supply, a predetermined value of a negative impedance to ground of the isolated power supply, and a range of voltages between the positive and negative electrodes of the isolated power supply.
Preferably, the minimum value is selected from the range of the positive reference voltage as the positive reference voltage, and the minimum value is selected from the range of the negative reference voltage as the negative reference voltage.
Preferably, the isolation detection circuit further comprises a comparison circuit including:
a first comparator having a positive input for receiving the positive detection voltage and a negative input for receiving the positive reference voltage;
a second comparator having a positive input terminal for receiving the negative reference voltage and a negative input terminal for receiving the negative detection voltage; and
and the first input end of the OR gate is used for receiving the data of the output end of the first comparator, the second input end of the OR gate is used for receiving the data of the output end of the second comparator, and the output end of the OR gate is used for outputting an isolation abnormity alarm signal.
Preferably, when the output value of the or gate is 1, an isolation abnormality alarm signal is issued.
The utility model discloses an whether isolation detection circuitry detects isolation circuit unusual through anodal detected voltage and the negative pole detected voltage after measuring the partial pressure. With direct measurement isolation resistance among the prior art, perhaps the anodal of corresponding measurement isolation power supply and the earth voltage of negative pole compare, the utility model discloses an it all is minimum quantity to keep apart among the detection circuitry measuring anodal detected voltage and negative pole detected voltage, can reduce the noise interference that brings to the earth current from this for measure more accurately, measured sensitivity is higher, has avoided the alert condition of wrong report.
Drawings
Fig. 1 is a schematic diagram of an isolation detection circuit according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a comparison circuit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly apparent, the present invention is further described in detail by the following embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Fig. 1 is a schematic diagram of an isolation detection circuit according to an embodiment of the present invention. As shown in FIG. 1, the isolated power source is a lithium battery with a voltage VbatAnd is the voltage between the positive and negative electrodes of the lithium battery. The voltage of the lithium battery has a certain attenuation with time, and the voltage V of the lithium battery is generallybatFor example, Vmin is 400V, Vmax is 576V, and Vmin and Vmax are fixed values for a particular lithium battery. The isolation resistor Rx is the equivalent resistance of the anode of the lithium battery to the Ground (GND), and the voltage at two ends of the resistor Rx is V+I.e. the voltage of the positive pole of the lithium battery to ground, the voltage value is a positive value. The isolation resistor Ry is the equivalent resistance of the negative pole of the lithium battery to the ground, and the voltage at two ends of the resistor Ry is V-Namely, the voltage of the negative pole of the lithium battery to the ground, the voltage value is negative. It should be understood that the resistor Rx and the resistor Ry are equivalent resistors, which are actually located inside the lithium battery, and are shown in fig. 1 for ease of understanding.
The isolation detection circuit includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4. One end of the first resistor R1 is connected to the anode of the lithium battery, the other end of the first resistor R1 is connected to the second resistor R2, the other end of the second resistor R2 is connected to the ground, and the voltage across the second resistor R2 is the anode detection voltage V1. One end of the third resistor R3 is connected to ground, the other end is connected to the fourth resistor R4, the other end of the fourth resistor R4 is connected to the negative electrode of the lithium battery, and the voltage across the third resistor R3 is the negative electrode detection voltage V2.
The circuit in fig. 1 yields:
Vbat＝V++|V-| (1)
substituting equations (2) and (3) into equation (1) yields:
since the current of the positive electrode of the lithium battery to the ground is equal to the current of the negative electrode to the ground, the following equation can be obtained:
substituting equations (2) and (3) into equation (5) yields:
preferably, the first resistor R1 is the same as the fourth resistor R4, i.e., R1 equals R4, and the second resistor R2 is the same as the third resistor R3, i.e., R2 equals R3, where equation (7) can be further simplified as:
preferably, the first resistor R1 is greater than the second resistor R2, and the fourth resistor R4 is greater than the third resistor R3. More preferably, the first resistor R1 is larger than 10 times the second resistor R2, so that the value of the positive detection voltage V1 is much smaller than the voltage V of the positive electrode of the lithium battery to the ground+. Preferably, the fourth resistor R4 is larger than 10 times the third resistor R3, so that the absolute value of the negative detection voltage V2 is much smaller than the voltage V of the negative electrode of the lithium battery to the ground-Absolute value of (a).
The isolation between the positive electrode and the negative electrode of the lithium battery can be detected by measuring the values of the positive electrode detection voltage V1 and the negative electrode detection voltage V2. Specifically, the positive detection voltage V1 and the preset positive reference voltage V may be comparedRef+(the voltage value is positive) and comparing the negative detection voltage V2 with a predetermined negative reference voltage VRef-(the voltage value is negative) when V1 is more than VRef+Or | V2| > | VRef-And if yes, sending an isolation abnormity alarm signal.
According to the utility model discloses an embodiment can be according to actual needs settlement positive reference voltage VRef+And a negative reference voltage VRef-The value of (c). The positive reference voltage V can also be calculated and set according to the value of the isolation impedance to be achievedRef+And a negative reference voltage VRef-The value of (c). For example, for a lithium battery, it can be set that the isolation condition is satisfied when the isolation resistance Rx and the isolation resistance Ry are both greater than 100K Ω. Determined voltage V based on lithium batterybatAnd the determined values of the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 according to equation (4) and equation (7), i.e. the positive reference voltage V can be calculated respectivelyRef+And a negative reference voltage VRef-A range of values of (c). The positive reference voltage V can be selected from the above range as requiredRef+And a negative reference voltage VRef-The value of (c). For example, selected from the above rangesSelecting the minimum value as positive reference voltage VRef+And a negative reference voltage VRef-The maximum value of (c) may be selected from the above range as the positive reference voltage VRef+And a negative reference voltage VRef-The value of (c).
Fig. 2 is a schematic diagram of a comparison circuit according to an embodiment of the present invention. As shown in fig. 2, the comparison circuit includes a first comparator 201, a second comparator 202, and an or gate 203. The positive input terminal of the first comparator 201 is configured to receive the positive detection voltage V1 of the isolation detection circuit, and the negative input terminal is configured to receive the positive reference voltage VRef+. The positive input terminal of the second comparator 202 is for receiving the negative reference voltage VRef-And the negative input end is used for receiving a negative detection voltage V2 of the isolation detection circuit. A first input of the or-gate 203 is arranged to receive the output data of the first comparator 201, a second input of the or-gate 203 is arranged to receive the output data of the second comparator 202, and an output of the or-gate 203 is arranged to output an alarm signal. Table 1 shows the positive detection voltage V1 and the positive reference voltage VRef+And a negative detection voltage V2 and a negative reference voltage VRef-And the relation between the alarm signals.
Table 1: relation between positive detection voltage V1, negative detection voltage V2 and alarm signal
As can be seen from Table 1, only when V1 is not more than VRef+And | V2| < | V |Ref-When | indicates that the isolation is normal, and when V1 > VRef+Or | V2| > | VRef-And when the voltage is lower than the preset voltage, the isolation abnormality is represented, and an isolation abnormality alarm signal is sent out.
According to the above embodiment, the utility model discloses an isolation detection circuitry detects isolation circuit whether unusual through positive pole detected voltage V1 and negative pole detected voltage V2 after measuring the partial pressure. The voltage V at two ends of the isolation resistor Rx and Ry or the corresponding isolation resistor Rx is measured in the prior art+And isolating the resistor Ry acrossPressure V-Compared with the prior art, the utility model discloses a positive pole detection voltage V1 and negative pole detection voltage V2 of measurement among the isolation detection circuit are for voltage V+And V-The method has the advantages that the method is extremely small, so that noise interference brought by the ground current can be reduced, the measurement is more accurate, the measurement sensitivity is higher, and the condition of false alarm is avoided. And the utility model provides an keep apart detection circuitry simple structure can reduce the detection cost.
Although the above embodiment has been described by taking a lithium battery as an example, the present invention is not limited thereto, and the isolation detection circuit of the present invention can be applied to all isolation power supplies, such as batteries.
Although the present invention has been described in connection with the preferred embodiments, it is not intended to limit the invention to the embodiments described herein, but rather, to include various changes and modifications without departing from the scope of the invention.
Claims (10)
1. An isolation detection circuit for isolating a power supply, the isolation detection circuit comprising: a first resistor, a second resistor, a third resistor, and a fourth resistor,
one end of the first resistor is connected to the anode of the isolated power supply, the other end of the first resistor is connected to the second resistor, and the other end of the second resistor is connected to the ground;
one end of the third resistor is connected to the ground, the other end of the third resistor is connected to the fourth resistor, and the other end of the fourth resistor is connected to the negative electrode of the isolated power supply;
comparing the positive detection voltage measured across the second resistor with a preset positive reference voltage and comparing the negative detection voltage measured across the third resistor with a preset negative reference voltage to determine whether the isolation between the positive and negative electrodes of the isolated power supply is abnormal.
2. The isolation detection circuit for the isolated power supply of claim 1, wherein the first resistor is the same as the fourth resistor, and the second resistor is the same as the third resistor.
3. The isolation detection circuit for the isolated power supply of claim 1, wherein the first resistance is greater than the second resistance, and the fourth resistance is greater than the third resistance.
4. The isolation detection circuit for the isolated power supply of claim 3, wherein the first resistance is greater than 10 times the second resistance, and the fourth resistance is greater than 10 times the third resistance.
5. The isolation detection circuit for an isolated power supply of claim 1, wherein the isolated power supply is a lithium battery.
6. The isolation detection circuit for the isolated power supply of claim 1, wherein an isolation anomaly alarm signal is issued when the positive detection voltage is greater than the positive reference voltage or the absolute value of the negative detection voltage is greater than the absolute value of the negative reference voltage.
7. The isolation detection circuit for the isolated power supply of claim 1, wherein the range of the positive reference voltage and the range of the negative reference voltage are calculated from a value of a positive ground impedance of a predetermined isolated power supply, a value of a negative ground impedance of a predetermined isolated power supply, and a range of voltages between the positive and negative poles of the isolated power supply.
8. The isolation detection circuit for the isolated power supply of claim 7, wherein a minimum value is selected from the range of positive reference voltages as a positive reference voltage and a minimum value is selected from the range of negative reference voltages as a negative reference voltage.
9. The isolation detection circuit for an isolated power supply of any of claims 1-8, wherein the isolation detection circuit further comprises a comparison circuit comprising:
a first comparator having a positive input for receiving the positive detection voltage and a negative input for receiving the positive reference voltage;
a second comparator having a positive input for receiving the negative reference voltage and a negative input for receiving the negative detection voltage; and
and the first input end of the OR gate is used for receiving the data of the output end of the first comparator, the second input end of the OR gate is used for receiving the data of the output end of the second comparator, and the output end of the OR gate is used for outputting an isolation abnormity alarm signal.
10. The isolation detection circuit for an isolated power supply of claim 9, wherein an isolation anomaly alarm signal is issued when the output value of the or gate is 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122909187.5U CN216748022U (en) | 2021-11-25 | 2021-11-25 | Isolation detection circuit for isolating power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122909187.5U CN216748022U (en) | 2021-11-25 | 2021-11-25 | Isolation detection circuit for isolating power supply |
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| Publication Number | Publication Date |
|---|---|
| CN216748022U true CN216748022U (en) | 2022-06-14 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202122909187.5U Active CN216748022U (en) | 2021-11-25 | 2021-11-25 | Isolation detection circuit for isolating power supply |
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- 2021-11-25 CN CN202122909187.5U patent/CN216748022U/en active Active
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