CN211697978U - Automobile insulation resistance detection circuit - Google Patents
Automobile insulation resistance detection circuit Download PDFInfo
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- CN211697978U CN211697978U CN201922220998.7U CN201922220998U CN211697978U CN 211697978 U CN211697978 U CN 211697978U CN 201922220998 U CN201922220998 U CN 201922220998U CN 211697978 U CN211697978 U CN 211697978U
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Abstract
The utility model provides an automobile insulation resistance detection circuitry, include: a first detection terminal; a second detection terminal; a first detection resistor connected between the first detection terminal and ground; a second detection resistor connected between the second detection terminal and ground; a first resistor; a first switching unit connected between the first detection terminal and the first resistor; a first resistor connected between the first switching unit and ground; the first differential voltage acquisition circuit is connected between the first detection terminal and the ground; and the second differential voltage acquisition circuit is connected between the second detection terminal and the ground, calculates the resistance values of the first detection resistor and the second detection resistor by controlling the on-off of the first switch unit, and determines the insulation resistance of the automobile according to the resistance values of the first detection resistor and the second detection resistor. Through the embodiment of the utility model provides a, can reliable and stable measurement car insulation resistance to do not influence the normal work of system.
Description
Technical Field
The embodiment of the utility model provides a relate to insulating detection area, especially relate to an automobile insulation resistance detection circuitry.
Background
With the vigorous popularization of environment-friendly electric automobiles, more and more electric automobiles enter the market. The safety problem of the electric vehicle gradually becomes one of the important indexes concerned by the industry, and the power source of the electric vehicle is a high-voltage battery pack which is a high-voltage system, so that the electrical insulation system is an important item of high-voltage safety of the electric vehicle. If the electrical insulation system fails, the leakage current will flow between the two points and accumulate heat on nearby materials, which is very likely to cause fire. Meanwhile, the normal work of electricity can be affected by insulation failure, and in severe cases, the occurrence of electric shock of people can be caused by the insulation failure.
In order to ensure effective insulation between the high-voltage battery pack of the electric vehicle and the vehicle body, an insulation detection unit needs to be equipped for the electric vehicle so as to measure the insulation resistance of the power battery system. In the existing insulation resistance measurement technology, a test signal can form ripple interference in a system, and the normal operation of the system is influenced.
SUMMERY OF THE UTILITY MODEL
In view of the above, there is a need for an automobile insulation resistance detection circuit for stably and reliably measuring the insulation resistance of an automobile without affecting the normal operation of the system.
In order to achieve the above object, an embodiment of the utility model provides an automobile insulation resistance detection circuit, include:
a first detection terminal;
a second detection terminal;
the first detection resistor is connected between the first detection terminal and the ground of the automobile chassis;
the second detection resistor is connected between the second detection terminal and the ground of the automobile chassis;
a first resistor;
a first switch unit connected between the first detection terminal and the first resistor;
the first resistor is connected between the first switch unit and the ground of the automobile chassis;
the first differential voltage acquisition circuit is connected between the first detection terminal and the ground of the automobile chassis;
the second differential voltage acquisition circuit is connected between the second detection terminal and the ground of the automobile chassis;
when the first switch unit is switched off, the first differential voltage acquisition circuit acquires a first output voltage, and the second differential voltage acquisition circuit acquires a second output voltage; when the first switch unit is closed, the first differential voltage acquisition circuit acquires third output voltage, the second differential voltage acquisition circuit acquires fourth output voltage, the resistance values of the first detection resistor and the second detection resistor are calculated according to the first output voltage, the second output voltage, the third output voltage and the fourth output voltage, the resistance values of the first detection resistor and the second detection resistor are compared, and the resistor with the larger resistance value of the first detection resistor and the second detection resistor is used as the insulation resistor of the automobile.
Preferably, the automobile insulation resistance detection circuit further includes:
a second resistor;
a second switching unit connected between the second detection terminal and the second resistor;
and the second resistor is connected between the second switch unit and the ground of the automobile chassis.
Preferably, the first differential voltage acquisition circuit comprises a first filter circuit, a first voltage stabilizing circuit and a first differential amplification circuit;
two ends of the first filter circuit are respectively connected between the first detection terminal and the ground of the automobile chassis in series through a third resistor and a fourth resistor;
the first differential amplifying circuit and the first voltage stabilizing circuit are respectively connected to two ends of the first filter circuit in parallel.
Preferably, the first filter circuit includes a first capacitor and a second capacitor, the first capacitor is connected between the third resistor and an analog ground, and the second capacitor is connected between the fourth resistor and the analog ground.
Preferably, the first voltage stabilizing circuit includes a first diode and a second diode, a cathode of the first diode is connected between the first differential amplifying circuit and the third resistor, an anode of the first diode is connected with an anode of the second diode, and a cathode of the second diode is connected between the first differential amplifying circuit and the fourth resistor.
Preferably, the first differential amplifier circuit includes a first differential amplifier, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor, the fifth resistor is connected between the third resistor and the non-inverting terminal of the first differential amplifier, the sixth resistor is connected between the non-inverting terminal of the first differential amplifier and the analog ground, the seventh resistor is connected between the fourth resistor and the inverting terminal of the first differential amplifier, and the eighth resistor is connected between the inverting terminal of the first differential amplifier and the output terminal of the first differential amplifier.
Preferably, the resistance of the third resistor is equal to the resistance of the fourth resistor, the resistance of the fifth resistor is equal to the resistance of the seventh resistor, and the resistance of the sixth resistor is equal to the resistance of the eighth resistor.
Preferably, the automobile insulation resistance detection circuit further includes a first impedance resistor connected between the output terminal of the first differential amplification circuit and the fifth voltage terminal.
Preferably, the first switch unit is a high-voltage optical coupling switch network.
Preferably, the second differential voltage acquisition circuit is identical to the first differential voltage acquisition circuit.
The embodiment of the utility model provides a car insulation resistance detection circuitry through insert two detection resistance between the positive negative pole of battery, through the break-make of switch element among the control circuit to obtain the magnitude of voltage on the resistance under the different states, and according to the magnitude of voltage calculates out the resistance of two electricity measuring resistance, with the insulating condition of definite battery positive and negative pole to ground.
Drawings
Fig. 1 is a schematic circuit diagram of an embodiment of the insulation resistance detection circuit of the present invention;
fig. 2 is a schematic circuit diagram of another embodiment of the insulation resistance detection circuit of the present invention;
FIG. 3 is a schematic circuit diagram of the first differential voltage acquisition circuit of FIG. 1;
FIG. 4 is a circuit schematic of a second differential voltage acquisition circuit of FIG. 1;
fig. 5 is a schematic circuit diagram of an insulation resistance detection 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 understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. In the drawings, like reference numbers can indicate functionally identical or similar elements. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.
The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.
Furthermore, in the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present invention. It will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.
It should be noted that the description relating to "first", "second", etc. in the present invention is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.
Referring to fig. 1, a schematic circuit diagram of an embodiment of the insulation resistance detection circuit of the present invention is shown. As shown in fig. 1, the insulation detection circuit mainly includes:
a first detection terminal VHP 1;
a second detection terminal VHN 1;
a first detection resistor Rx connected between the first detection terminal VHP1 and a ground of a chassis of the vehicle;
a second sensing resistor Ry connected between the second sensing terminal VHN1 and a ground of the vehicle chassis;
a first resistor R1;
a first switching unit 10 connected between the first detection terminal VHP1 and the first resistor R1;
the first resistor R1 is connected between the first switch unit 10 and the ground of the automobile chassis;
a first differential voltage acquisition circuit 30 connected between the first detection terminal VHP1 and a ground of the vehicle chassis;
a second differential voltage acquisition circuit 40 connected between the second detection terminal VHN1 and the ground of the vehicle chassis;
when the first switch unit 10 is turned off, the first differential voltage acquisition circuit 30 acquires a first output voltage, and the second differential voltage acquisition circuit 40 acquires a second output voltage; when the first switch unit 10 is closed, the first differential voltage acquisition circuit 30 acquires a third output voltage, the second differential voltage acquisition circuit 40 acquires a fourth output voltage, the resistance values of the first detection resistor Rx and the second detection resistor Ry are calculated according to the first output voltage, the second output voltage, the third output voltage, and the fourth output voltage, the resistance values of the first detection resistor Rx and the second detection resistor Ry are compared, and a resistor with a large resistance value in the first detection resistor Rx and the second detection resistor Ry is used as an insulation resistor of the automobile.
Specifically, when the first switch 10 is turned off, the first detection resistor Rx and the first differential voltage collecting circuit 30 form a parallel circuit, the second detection resistor Ry and the second differential voltage collecting circuit 40 form a parallel circuit, the first differential voltage collecting circuit 30 collects the first output voltage V1, and the second differential voltage collecting circuit 40 collects the second output voltage V2. When the first switch unit 10 is closed, the first detection resistor Rx, the first resistor R1 and the first differential voltage collecting circuit 30 form a parallel circuit, and after the parallel circuit is connected in parallel, the resistance of the parallel circuit changes (the resistance becomes smaller), the second detection resistor Ry and the second differential voltage collecting circuit 40 form a parallel circuit, the first differential voltage collecting circuit 30 collects a third output voltage V1', and the second differential voltage collecting circuit 40 collects a fourth output voltage V2'.
When the first switch unit 10 is turned off, since the first detection resistor Rx and the first differential voltage acquisition circuit 30 are connected in parallel, the first output voltage V1 is the voltage of the first detection resistor Rx when the first switch unit 10 is turned off; since the second detection resistor Ry is connected in parallel with the second differential voltage collecting circuit 40, the second output voltage V2 is the voltage of the second detection resistor Ry when the first switching unit 10 is turned off. When the first switch unit 10 is closed, since the first detection resistor Rx and the first differential voltage acquisition circuit 30 are connected in parallel, the third output voltage V1' is the voltage of the first detection resistor Rx when the first switch unit 10 is closed; since the second detection resistor Ry is connected in parallel with the second differential voltage collecting circuit 40, the second output voltage V2' is the voltage of the second detection resistor Ry when the first switch unit 10 is closed.
As shown in fig. 1, since the first detection resistor Rx and the second detection resistor Ry are connected to the ground of the chassis of the vehicle, the first detection resistor Rx and the second detection resistor Ry each have a terminal having a potential of 0, the voltage of the first detection resistor Rx is the voltage value at the terminal of the first detection terminal VHP1, and the voltage of the second detection resistor Ry is the voltage value at the terminal of the second detection terminal VHN 1. If the voltage at the first detection terminal VHP1 is VA, the voltage at the second detection terminal VHN1 is VB. When the first switch unit 10 is turned off, the first detection resistor Rx and the second detection resistor Ry are connected in series, and according to the relationship that the currents in the series circuits are equal:
due to the voltage amplification principle of the first and second differential voltage collecting circuits 30 and 40, if the first output voltage V1 is a constant multiple of the voltage VA at the terminal of the first detection terminal VHP1 and the second output voltage V2 is a constant multiple of the voltage VB at the terminal of the second detection terminal VHN1, then:
when the first switch unit 10 is closed, the first detection resistor Rx and the first resistor R1 are connected in parallel, and the parallel resistor is connected in series with the second detection resistor Ry. Due to the voltage amplification principle of the first differential voltage collecting circuit 30 and the second differential voltage collecting circuit 40, if the first output voltage V1 'is a constant multiple of the voltage VA at the terminal of the first detection terminal VHP1, and the second output voltage V2' is a constant multiple of the voltage VB at the terminal of the second detection terminal VHN1, there are:
the formula (i) and the formula (ii) are jointly calculated, since R1 is a known resistor, and in the embodiment, R1 is 1M Ω, the first output voltages V1 and V1 'and the second output voltages V2 and V2' can be acquired by the first differential voltage acquisition circuit 30 and the second differential voltage acquisition circuit 40, and then the resistance values of the first detection resistor Rx and the second detection resistor Ry can be calculated respectively.
The embodiment of the utility model provides a disconnection and closure through the first switch unit of control to through differential voltage acquisition circuit in order to calculate first detection resistance with the resistance of second detection resistance can realize the reliable and stable measurement of insulation resistance among the electric power battery system, and does not influence the normal work of system.
In an exemplary embodiment, with reference to fig. 2, the insulation resistance detection circuit further includes, in addition to the components in fig. 1:
a second resistor R2;
a second switching unit 20 connected between the second detection terminal VHN1 and the second resistor R2;
the second resistor R2 is connected between the second switch unit 20 and the ground of the vehicle chassis.
Specifically, when the first switching unit 10 fails, the first and second detection resistors Rx and Ry may be measured by controlling the opening and closing of the second switch 20.
It should be noted that, the first switch unit 10 and the second switch unit 20 are in a main-standby relationship, and when the first switch unit 10 is normal, the second switch unit 20 may be opened, and the first detection resistor Rx and the second detection resistor Ry may be measured by controlling the opening and closing of the first switch unit 10. When the first switch unit 10 is damaged, that is, the first switch unit 10 is always in an open state or an open state, the second switch unit 20 is controlled to be opened and closed to measure the first detection resistor Rx and the second detection resistor Ry, and the specific calculation process is the same as the above calculation process, which is not repeated herein. In the embodiment of the present invention, when the first switch unit 10 can be normally opened and closed and the second switch unit 20 is always in the open state, the opening and closing of the first switch unit 10 are controlled as an example to be described in detail. The first switch unit 10 and the second switch unit 20 may be high-voltage optical coupling switch networks.
In an exemplary embodiment, please refer to fig. 2, which is a circuit diagram of the first differential voltage collecting circuit in fig. 1. The first differential voltage collecting circuit 30 may include a first filter circuit 31, a first voltage stabilizing circuit 32 and a first differential amplifying circuit 33;
both ends of the first filter circuit 31 are connected in series between the first detection terminal VHP1 and the ground of the vehicle chassis through a third resistor R3 and a fourth resistor R4, respectively;
the first differential amplifier circuit 33 and the first voltage regulator circuit 32 are connected in parallel to the first filter circuit 31 at both ends of the first filter circuit 31, respectively.
Specifically, in practical applications, the third resistor R3 and the fourth resistor R4 may respectively include a plurality of resistors. For convenience of calculation, the third resistor R3 and the fourth resistor R4 may be set to have equal resistance values, that is, the sum of the resistance values of the plurality of resistors equivalent to the third resistor R3 is equal to the sum of the resistance values of the plurality of resistors equivalent to the fourth resistor R4. Referring to fig. 3, the resistance values of the third resistor R3 and the fourth resistor R4 may be 3M Ω, respectively. Illustratively, to reach 3M Ω, the resistances of the third resistor R3 and the fourth resistor R4 may be implemented by a series connection of a plurality of resistors.
In an exemplary embodiment, fig. 4 is a specific circuit schematic diagram of an insulation resistance detection circuit according to an embodiment of the present invention. The first filter circuit 31 may include a first capacitor C1 and a second capacitor C2, the first capacitor C1 is connected between the third resistor R3 and an analog ground, and the second capacitor C2 is connected between the fourth resistor R4 and the analog ground. The interference of electromagnetic waves can be filtered out by the first filter circuit 31. In this embodiment, the parameters of the first capacitor C1 and the second capacitor C2 may be 30 pF/50V.
The first voltage stabilizing circuit 32 comprises a first diode D1 and a second diode D2, wherein the cathode of the first diode D1 is connected between the first differential amplifier circuit 33 and the third resistor R3, the anode of the first diode D1 is connected with the anode of the second diode D2, and the cathode of the second diode D2 is connected between the first differential amplifier circuit 33 and the fourth resistor R4. In the present embodiment, the first diode D1 and the second diode D2 may be BZT52C22-7-F diodes.
Specifically, when a current passes through the cathode of the first diode D1 and the cathode of the second diode D2, the current will not pass through the first diode D1 and the second diode D2 due to the reverse blocking characteristic of the diodes, and when a certain breakdown voltage threshold is reached, the zener diode will break down in the reverse direction, thereby achieving the effect of stabilizing the voltage.
The first differential amplifier circuit 33 includes a first differential amplifier U2A, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, and an eighth resistor R8, the fifth resistor R5 is connected between the third resistor R3 and the non-inverting terminal of the first differential amplifier 33, the sixth resistor R6 is connected between the non-inverting terminal of the first differential amplifier 33 and the analog ground, the seventh resistor R7 is connected between the fourth resistor R4 and the inverting terminal of the first differential amplifier 33, and the eighth resistor R8 is connected between the inverting terminal of the first differential amplifier 33 and the output terminal of the first differential amplifier 33. In this embodiment, the resistances of the fifth resistor R5, the sixth resistor R6, the seventh resistor R7 and the eighth resistor R8 may all be 10K Ω.
The output voltage of the first differential amplifier 33 can be calculated according to the principle of the virtual short-break of the differential amplifier. Referring to fig. 1, when the first switch unit 10 is turned off, the voltage at the end point of the first detection terminal VHP1 is VA, the voltage at the non-inverting end of the first differential amplifier 33 is V +, and the voltage at the inverting end of the first differential amplifier 33 is V-The calculation formula is as follows:
V+＝V-；........................⑤
by substituting R3 ═ R4, R5 ═ R7, and R6 ═ R8 into the above equation, it can be calculated:
from the above calculation results, it can be seen that the first output voltage V1 and the voltage V at the end of the first detection terminal VHP1AProportional relation, and the ratio is a constant.
In particular, the first and second differential amplifiers U2A and U2B may be LMC6482 CMOS dual rail-to-rail input and output operational amplifiers.
In an exemplary embodiment, please refer to fig. 3, which is a circuit diagram of the second differential voltage collecting circuit in fig. 1. The second differential voltage collecting circuit 40 is the same as the first differential voltage collecting circuit 30 shown in fig. 2, except that names and labels of electrical components in this embodiment are different, and functions of each electrical component are the same as those of the first differential voltage collecting circuit 30, and are not repeated in this embodiment. In order to describe the reference numbers of each electrical component corresponding to fig. 3, the connection relationship between each electrical component is described simply in conjunction with the reference numbers of each electrical component, specifically as follows:
the second differential voltage acquisition circuit 40 comprises a second filter circuit 41, a second voltage stabilizing circuit 42 and a second differential amplification circuit 43;
two ends of the second filter circuit 41 are respectively connected between the ground of the automobile chassis and the second detection terminal VHN1 in series through a tenth resistor R10 and an eleventh resistor R11;
the second differential amplifier circuit 43 and the second voltage regulator circuit 42 are respectively connected in parallel with the second filter circuit 41 at two ends of the second filter circuit 41.
The second filter circuit 41 includes a third capacitor C3 and a fourth capacitor C4, the third capacitor C3 is connected between the tenth resistor R10 and the analog ground, and the fourth capacitor C4 is connected between the eleventh resistor R11 and the analog ground. In this embodiment, the parameters of the third capacitor C3 and the fourth capacitor C4 may be 30 pF/50V.
The second stabilizing circuit 42 includes a third diode D3 and a fourth diode D4, a cathode of the third diode D3 is connected between the second differential amplifier circuit 43 and the tenth resistor R10, an anode of the third diode D3 is connected to an anode of the fourth diode D4, and a cathode of the fourth diode D4 is connected between the second differential amplifier circuit 43 and the eleventh resistor R11. In the present embodiment, the third diode D3 and the fourth diode D4 may be BZT52C22-7-F diodes.
The second differential amplifier circuit 43 includes a second differential amplifier U2B, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14 and a fifteenth resistor R15, the twelfth resistor R12 is connected between the tenth resistor R10 and the non-inverting terminal of the second differential amplifier U2B, the thirteenth resistor R13 is connected between the non-inverting terminal of the second differential amplifier U2B and the analog ground, the fourteenth resistor R14 is connected between the eleventh resistor R11 and the inverting terminal of the second differential amplifier U2B, and the fifteenth resistor R15 is connected between the inverting terminal of the second differential amplifier U2B and the output terminal of the second differential amplifier U2B. In this embodiment, the resistance values of the tenth resistor R10 and the eleventh resistor R11 may be 3M Ω, and the resistance values of the twelfth resistor R12, the thirteenth resistor R13, the fourteenth resistor R14 and the fifteenth resistor R15 may be 10K Ω.
As can be seen from fig. 4 and the above description, the second differential voltage acquisition circuit 40 is the same as the first differential voltage acquisition circuit 30, so the calculation formula is the same, and is not repeated herein. If the voltage at the second detection terminal VHN1 is VBCombining the above calculation formula, it can calculate:
from the above calculation results, it can be seen that the second output voltage V2 and the endpoint voltage V of the second detection terminal VHN2BProportional relation, the ratio is also a constant.
Referring to fig. 1, when the first switch unit 10 is turned off, the actual voltage across Rx is VAThe actual voltage across Ry is VBTherefore, it is
Since V1 and V2 are the output voltages of the voltage differential amplifier circuit, the voltage can be directly measured. R4, R7, R8, R11, R14 and R15 are constants, so V1 and VAIn a constant direct proportional relationship, V2 and VBIs in a constant direct proportional relationship.
Can be equivalently expressed as formula ①
The relationship equation of Rx and Ry is obtained by substituting the measured values of V1 and V2 into equation ①.
Similarly, when the first switch unit 10 is closed, the measured values of V1 'and V2' are substituted into formula ②
To obtain another relationship equation for Rx and Ry. Combining these two equations, the resistance values of Rx and Ry can be calculated. The calculated resistance values of Rx and Ry are then compared to determine the resistance magnitude relationship of Rx and Ry.
In an exemplary embodiment, with continuing reference to fig. 4, the vehicle insulation resistance detection circuit further includes a first impedance resistor R9 connected between the output terminal of the first differential amplifying circuit 33 and a fifth voltage terminal ISO _ SAMP 1; the vehicle insulation resistance detection circuit further includes a second resistance resistor R16 connected between the output terminal of the second differential amplifier circuit 43 and a sixth voltage terminal ISO _ SAMP 2. The first impedance resistor R9 and the second impedance resistor R16 are mainly used as current limiting resistors, and when a rear-stage circuit is short-circuited, the operational amplifier is protected from being damaged.
In an exemplary embodiment, with continuing reference to fig. 4, the vehicle insulation resistance detection circuit further includes a fifth capacitor C5 and a sixth capacitor C6, the fifth capacitor C5 is connected between the power supply terminal PV5P0 of the first differential amplifier U2A and the analog ground, and the sixth capacitor C6 is connected between the power supply terminal PV5P0 of the second differential amplifier U2B and the analog ground, and performs a filtering function. The parameters of the fifth capacitor C5 and the sixth capacitor C6 may be 0.1 uF/50V.
The embodiment of the utility model provides a car insulation resistance detection circuitry through insert two detection resistance between the positive negative pole of battery, through the break-make of switch element among the control circuit to obtain the magnitude of voltage on the resistance under the different states, and according to the magnitude of voltage calculates out the resistance of two electricity measuring resistance, with the insulating condition of definite battery positive and negative pole to ground.
The above embodiment numbers of the present invention are only for description, and do not represent the advantages and disadvantages of the embodiments.
Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner.
The above is only the preferred embodiment of the present invention, and not the scope of the present invention, all the equivalent structures or equivalent flow changes made by the contents of the specification and the drawings or the direct or indirect application in other related technical fields are included in the patent protection scope of the present invention.
Claims (10)
1. An automotive insulation resistance detection circuit, comprising:
a first detection terminal;
a second detection terminal;
the first detection resistor is connected between the first detection terminal and the ground of the automobile chassis;
the second detection resistor is connected between the second detection terminal and the ground of the automobile chassis;
a first resistor;
a first switch unit connected between the first detection terminal and the first resistor;
the first resistor is connected between the first switch unit and the ground of the automobile chassis;
the first differential voltage acquisition circuit is connected between the first detection terminal and the ground of the automobile chassis;
the second differential voltage acquisition circuit is connected between the second detection terminal and the ground of the automobile chassis;
when the first switch unit is switched off, the first differential voltage acquisition circuit acquires a first output voltage, and the second differential voltage acquisition circuit acquires a second output voltage; when the first switch unit is closed, the first differential voltage acquisition circuit acquires third output voltage, the second differential voltage acquisition circuit acquires fourth output voltage, the resistance values of the first detection resistor and the second detection resistor are calculated according to the first output voltage, the second output voltage, the third output voltage and the fourth output voltage, the resistance values of the first detection resistor and the second detection resistor are compared, and the resistor with the large resistance value in the first detection resistor and the second detection resistor is used as the insulation resistor of the automobile.
2. The automotive insulation resistance detection circuit of claim 1, further comprising:
a second resistor;
a second switching unit connected between the second detection terminal and the second resistor;
and the second resistor is connected between the second switch unit and the ground of the automobile chassis.
3. The automotive insulation resistance detection circuit of claim 1, wherein:
the first differential voltage acquisition circuit comprises a first filter circuit, a first voltage stabilizing circuit and a first differential amplification circuit;
two ends of the first filter circuit are respectively connected between the first detection terminal and the ground of the automobile chassis in series through a third resistor and a fourth resistor;
the first differential amplifying circuit and the first voltage stabilizing circuit are respectively connected to two ends of the first filter circuit in parallel.
4. The automotive insulation resistance detection circuit of claim 3, wherein the first filter circuit comprises a first capacitor and a second capacitor, the first capacitor being connected between the third resistor and an analog ground, the second capacitor being connected between the fourth resistor and the analog ground.
5. The automotive insulation resistance detection circuit of claim 3, wherein the first regulator circuit includes a first diode and a second diode, a cathode of the first diode is connected between the first differential amplifier circuit and the third resistor, an anode of the first diode is connected to an anode of the second diode, and a cathode of the second diode is connected between the first differential amplifier circuit and the fourth resistor.
6. The vehicle insulation resistance detection circuit according to claim 4, wherein the first differential amplifier circuit includes a first differential amplifier, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor, the fifth resistor is connected between the third resistor and the non-inverting terminal of the first differential amplifier, the sixth resistor is connected between the non-inverting terminal of the first differential amplifier and the analog ground, the seventh resistor is connected between the fourth resistor and the inverting terminal of the first differential amplifier, and the eighth resistor is connected between the inverting terminal of the first differential amplifier and the output terminal of the first differential amplifier.
7. The automobile insulation resistance detection circuit according to claim 6, wherein a resistance value of the third resistor is equal to a resistance value of the fourth resistor, a resistance value of the fifth resistor is equal to a resistance value of the seventh resistor, and a resistance value of the sixth resistor is equal to a resistance value of the eighth resistor.
8. The vehicle insulation resistance detection circuit according to claim 3 or 6, further comprising a first impedance resistor connected between the output terminal of the first differential amplification circuit and the fifth voltage terminal.
9. The automobile insulation resistance detection circuit according to claim 1, wherein the first switch unit is a high-voltage optocoupler switch network.
10. The automotive insulation resistance detection circuit of claim 1, wherein the second differential voltage acquisition circuit is identical to the first differential voltage acquisition circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922220998.7U CN211697978U (en) | 2019-12-09 | 2019-12-09 | Automobile insulation resistance detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922220998.7U CN211697978U (en) | 2019-12-09 | 2019-12-09 | Automobile insulation resistance detection circuit |
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| CN211697978U true CN211697978U (en) | 2020-10-16 |
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| CN201922220998.7U Active CN211697978U (en) | 2019-12-09 | 2019-12-09 | Automobile insulation resistance detection circuit |
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2019
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