CN116047167A - Self-applicability insulation detection circuit and detection method for electric automobile - Google Patents

Self-applicability insulation detection circuit and detection method for electric automobile Download PDF

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CN116047167A
CN116047167A CN202310043617.0A CN202310043617A CN116047167A CN 116047167 A CN116047167 A CN 116047167A CN 202310043617 A CN202310043617 A CN 202310043617A CN 116047167 A CN116047167 A CN 116047167A
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relay
resistor
voltage
insulation
circuit
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张龙聪
刘威峰
刘彪
刘方勇
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Shandong Wuzheng Group Co Ltd
Zhejiang Feidie Automobile Manufacturing Co Ltd
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Shandong Wuzheng Group Co Ltd
Zhejiang Feidie Automobile Manufacturing Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/025—Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L3/00—Electric devices on electrically-propelled vehicles for safety purposes; Monitoring operating variables, e.g. speed, deceleration or energy consumption
    • B60L3/0023—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
    • B60L3/0069—Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train relating to the isolation, e.g. ground fault or leak current
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/14—Measuring resistance by measuring current or voltage obtained from a reference source
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

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Abstract

The invention discloses an electric automobile self-applicability insulation detection circuit and a detection method, wherein the detection circuit comprises an insulation resistance detection circuit, a quick charge circuit and a vehicle-mounted power circuit, the quick charge circuit and the insulation resistance detection circuit are connected in parallel and connected with the vehicle-mounted power circuit, and the insulation resistance detection circuit is used for detecting the insulativity of the vehicle-mounted power circuit; according to the invention, the time parameter can be selected according to different working modes of the vehicle, and the time parameter is changed into the sampling time of the insulation detection voltage, so that the time for completing the insulation detection can be changed, the defect of utilizing a fixed parameter is avoided, and the use safety of the vehicle is improved.

Description

Self-applicability insulation detection circuit and detection method for electric automobile
Technical Field
The invention belongs to the technical field of electric automobile control, and particularly relates to an electric automobile self-applicability insulation detection circuit and a detection method.
Background
The shorter the time for completing the insulation detection is, the better the time is, and the personal safety is more reliable, because the times of detecting the result in unit time are more, the vehicle can perform safety treatment according to the detection result; if the detection process takes too long, the human body can be damaged when contacting with the places where insulation such as a vehicle body is problematic during the detection process, so that the longer the detection time is, the better the detection time is, and the time of the existing vehicle models on the market is calibrated in order to adapt to the accompanying direct current charging piles; the calibrated time parameter is usually a fixed value, because the electric vehicle is in a relatively large number of working modes, obviously the rough handling mode is unreasonable, for example, in a driving mode, the Y capacitance of the whole vehicle is different from the Y capacitance of the whole vehicle in a direct current charging mode, so that the insulation voltage is sampled by using different time parameters, thereby shortening the insulation detection time according to the different working modes and better ensuring the personal safety.
In conclusion, the whole vehicle is not distinguished according to the working mode of the whole vehicle, and different time parameters are used for trampling insulation detection; the Y capacitance values of the direct current charging piles are different, and the current vehicles on the market are not matched according to the highest voltage value of the piles, and the insulation detection time is not shortened to the greatest extent.
Disclosure of Invention
The invention provides a self-adaptive insulation detection processing control method for an electric automobile, which solves the defect that the electric automobile in the market at present only uses one fixed calibration time parameter for insulation detection, and the problem that the completion time of insulation monitoring is prolonged and the safety risk of the automobile is increased by only using one fixed time parameter.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
the utility model provides an electric automobile self-adaptation insulation detection circuit, includes insulation resistance detection circuit, fills charge circuit soon and on-vehicle power circuit, fill charge circuit soon and insulation resistance detection circuit parallelly connected and with on-vehicle power circuit is connected, insulation resistance detection circuit is used for detecting on-vehicle power circuit's insulativity.
Preferably, the vehicle-mounted power circuit comprises a power battery pack, a main positive relay S1, a main negative relay S2, a pre-charging resistor R1, a pre-charging relay S5 and a capacitor;
the main positive relay S1, the pre-charging resistor R1 and the pre-charging relay S5 are connected in series and are connected with the power battery VBat+, and the main negative relay S2 is connected with the negative electrode of the power battery;
the capacitor Cy+ is connected between the positive pole of the power battery and the ground, and the capacitor Cy-is connected between the power battery VBat-and the ground.
Preferably, the fast charging loop comprises a fast charging positive electrode contactor S6, a fast charging negative electrode contactor S7, a direct current charging pile capacitor Cy pile+, a direct current charging pile capacitor Cy pile-and a direct current charging pile;
the positive pole of the direct current charging pile is connected with the main positive relay S1 through a fast charging positive pole contactor S6, and the negative pole of the direct current charging pile is connected with the main negative relay S2 through a fast charging negative pole contactor connection S7;
the direct-current charging pile capacitor Cy pile is connected between the positive electrode of the direct-current charging pile and the ground, and the direct-current charging pile capacitor Cy pile is connected between the negative electrode of the direct-current charging pile and the ground;
when the fast charging positive electrode contactor S6, the fast charging negative electrode contactor S7, the main positive relay S1 and the main negative relay S2 are all closed, the direct current charging pile is used for fast supplementing electricity to the power battery pack.
Preferably, the insulation resistance detection circuit comprises three detection unit groups formed by connecting resistors R and relays S in parallel;
the first group of detection units are formed by connecting a resistor Rp and a resistor Rn in series and are connected with the power battery pack;
the resistor Rp is an equivalent resistor of the power battery pack VBat+ to the ground, and the resistor Rn is an equivalent resistor of the power battery pack VBat-to the ground, which is not an actual resistor;
the second group of detection units are formed by connecting a resistor R2, a resistor R3, a resistor R7 and a resistor R6 in series and are connected with the power battery pack;
a voltage acquisition point Vhad is connected between the resistor R2 and the resistor R3, and a voltage acquisition point Vlad is connected between the resistor R7 and the resistor R6;
the third group of detection units are formed by serially connecting a relay S3, a resistor R4, a resistor R8 and the relay S4 and are connected with the power battery pack.
Preferably, the insulation resistance detection circuit, the capacitor cy+, the capacitor Cy-, the dc charging stake capacitor Cy stake+ and the dc charging stake capacitor Cy stake-form an RC circuit;
the RC circuit has the functions of filtering and anti-interference on the insulation detection circuit.
Preferably, the power battery pack is composed of a plurality of power batteries.
The invention also provides a detection method of the self-applicability insulation detection circuit of the electric automobile, which is applied to a battery management system and comprises the following steps:
step S1: the quick-charging positive electrode contactor S6, the quick-charging negative electrode contactor S7, the main positive relay S1 and the main negative relay S2 are controlled to be closed, and the direct-current charging pile power battery pack is subjected to quick power charging;
step S2: setting a positive electrode grounding voltage VH and a negative electrode grounding voltage VL on an insulation resistance detection circuit, acquiring VHad and Vlad voltage values by a battery management system, and calculating to obtain the positive electrode grounding voltage VH and the negative electrode grounding voltage VL;
Figure BDA0004051506670000031
the VHad is a resistor R3 voltage value measured by the sampling circuit;
Figure BDA0004051506670000032
the VLad is a voltage value of a resistor R7 obtained by measuring a sampling circuit;
step S3: the insulation detection is in an initial state and is ready to enter a first state (at this time S1/S2/S6/S7 is closed, S3/S4/S5 is open);
vbat=vh+vl (formula 1-a);
Figure BDA0004051506670000033
wherein:
VBAT represents the terminal voltage of the power battery pack, rcircuit= (r2+r3), RCircuit' = (r6+r7) in equation 1-b; VH and VL are measured with relay S1 and relay S2 closed; since the resistance values of (R2+R3) and (R6+R7) reach megaohms, VH and VL are assumed to be 250V,
VH
at maximum, rcircuit=milliamp level, which can be treated as 0, because it is much smaller than the safe electrical current of the human body by 2mA, which can be ignored, equation 1-b is treated as public 1-c;
Figure BDA0004051506670000034
deducing:
Figure BDA0004051506670000035
step S4: the insulation detection ends the first state and prepares to enter the second state;
control relay S3 closed, measure VH' voltage:
Figure BDA0004051506670000036
measuring VL' voltage:
Figure BDA0004051506670000041
wherein:
the positive ground voltage after closing the relay S3 is defined as VH ', and the negative ground voltage after closing the relay three S3 is defined as VL'; VHad' is the voltage sample value of resistor R3 after closing relay S3; VLad' is the voltage sample value of resistor R7 after closing relay S3;
from this, it can be seen that:
Figure BDA0004051506670000042
and (3) calculating a formula:
substituting formula 1-a and formula 1-d into formula 2-a; setting r0= (r2+r3)// r4, performing the operation results in:
Figure BDA0004051506670000043
further simplify:
Figure BDA0004051506670000044
further simplify:
Figure BDA0004051506670000045
further simplify:
Figure BDA0004051506670000046
substituting equation 1-d into equation 3-d yields further:
Figure BDA0004051506670000047
obtaining the resistance of the positive electrode to ground equivalent resistance Rp and the negative electrode to ground equivalent resistance Rn;
step S5: opening the relay S3, ending the second state of insulation detection, and preparing to enter a third state;
closing relay S4, making VH "measurements:
Figure BDA0004051506670000048
VL "measurements were made:
Figure BDA0004051506670000051
wherein:
the positive ground voltage after closing relay S4 is defined as VH ", and the negative ground voltage after closing relay S4 is defined as VL"; VHad "is the voltage sample value of the resistor R3 after closing the relay S4, VLad" is the voltage value of the resistor R7 after closing the relay S4;
from this, it can be seen that:
Figure BDA0004051506670000052
and (3) calculating a formula:
taking equations 1-a and 1-e into equations 2-b, let R0' = (R6+R7)// R8 perform the operation to obtain:
Figure BDA0004051506670000053
further simplify:
Figure BDA0004051506670000054
further simplify:
Figure BDA0004051506670000055
further simplify:
Figure BDA0004051506670000056
it is possible to take equation 1-e into equation 4-d:
Figure BDA0004051506670000057
the resistance of the positive electrode to ground equivalent resistance Rp and the negative electrode to ground equivalent resistance Rn is obtained.
Preferably, the insulation detects the second state and the insulation detects the smaller values of Rp and Rn reached by the third state measurement.
The beneficial effects of adopting above technical scheme are:
1. the time parameter can be selected according to different vehicle working modes, and is changed into the sampling time of the insulation detection voltage, so that the time for completing the insulation detection can be changed, the defect of utilizing a fixed parameter is avoided, and the use safety of the vehicle is improved.
2. The time parameter can be matched according to the highest voltage of the charging pile, so that the time for completing insulation detection can be changed, the defect of utilizing a fixed parameter is avoided, and the use safety of the vehicle is improved.
Drawings
Fig. 1 is a schematic diagram of a self-adaptive insulation detection circuit structure of an electric automobile.
Detailed Description
The following detailed description of the embodiments of the invention, given by way of example only, is presented in the accompanying drawings to aid in a more complete, accurate and thorough understanding of the concepts and aspects of the invention, and to aid in its practice, by those skilled in the art.
Example 1:
as shown in FIG. 1, the self-adaptive insulation detection circuit of the electric automobile comprises an insulation resistance detection circuit, a quick charging circuit and a vehicle-mounted power circuit, wherein the quick charging circuit and the insulation resistance detection circuit are connected in parallel and connected with the vehicle-mounted power circuit, and the insulation resistance detection circuit is used for detecting the insulativity of the vehicle-mounted power circuit.
Further, the vehicle-mounted power circuit comprises a power battery pack, a main positive relay S1, a main negative relay S2, a pre-charging resistor R1, a pre-charging relay S5 and a capacitor.
The main positive relay S1, the pre-charging resistor R1 and the pre-charging relay S5 are connected in series and are connected with the power battery VBat+, and the main negative relay S2 is connected with the negative electrode of the power battery; the capacitor Cy+ is connected between the positive electrode of the power battery pack and the ground, and the capacitor Cy-is connected between the power battery pack VBat-and the ground;
specifically, the power battery pack is composed of a plurality of power batteries.
Further, the quick charge loop comprises a quick charge positive electrode contactor S6, a quick charge negative electrode contactor S7, a direct current charge pile capacitor Cy pile+, a direct current charge pile capacitor Cy pile-and a direct current charge pile;
the positive pole of the direct current charging pile is connected with the main positive relay S1 through a fast charging positive pole contactor S6, and the negative pole of the direct current charging pile is connected with the main negative relay S2 through a fast charging negative pole contactor connection S7; the direct-current charging pile capacitor Cy pile is connected between the positive electrode of the direct-current charging pile and the ground, and the direct-current charging pile capacitor Cy pile is connected between the negative electrode of the direct-current charging pile and the ground;
when the fast charging positive electrode contactor S6, the fast charging negative electrode contactor S7, the main positive relay S1 and the main negative relay S2 are all closed, the direct current charging pile is used for fast supplementing electricity to the power battery pack.
Further, the insulation resistance detection circuit comprises three detection unit groups formed by connecting resistors R and relays S in parallel;
the first group of detection units are formed by connecting a resistor Rp and a resistor Rn in series and are connected with the power battery pack;
the insulation state of the self-adaptive insulation detection circuit of the electric automobile can be expressed by the insulation resistance to ground, and can comprise the insulation resistance to ground of the positive electrode and the insulation resistance to ground of the negative electrode; for example, rp connected by a dotted line in fig. 1 is an equivalent resistance of the power battery vbat+ to the ground, rn is an equivalent resistance of the power battery VBat-to-the ground, both are equivalent resistances, the dotted line is not connected in the actual vehicle circuit, but the resistance Rp and the resistance Rn are actually present, so that the insulation state of the electric vehicle self-adaptive insulation detection circuit can be obtained based on the resistance Rp and the resistance Rn.
The second group of detection units are formed by connecting a resistor R2, a resistor R3, a resistor R7 and a resistor R6 in series and are connected with the power battery pack; a voltage acquisition point Vhad is connected between the resistor R2 and the resistor R3, and a voltage acquisition point Vlad is connected between the resistor R7 and the resistor R6;
the third group of detection units are formed by serially connecting a relay S3, a resistor R4, a resistor R8 and the relay S4 and are connected with the power battery pack.
Further, the insulation resistance detection circuit, the capacitor Cy+, the capacitor Cy-, the DC charging pile capacitor Cy pile+ and the DC charging pile capacitor Cy pile-form an RC circuit;
the RC circuit has the functions of filtering and anti-interference on the insulation detection circuit.
Example 2:
an electric automobile self-adaptation insulation detection circuit is applied to a battery management system and comprises the following steps:
step S1: the quick-charging positive electrode contactor S6, the quick-charging negative electrode contactor S7, the main positive relay S1 and the main negative relay S2 are controlled to be closed, and the direct-current charging pile power battery pack is subjected to quick power charging;
step S2: setting a positive electrode-to-ground voltage VH and a negative electrode-to-ground voltage VL on an insulation resistance detection circuit, wherein the voltages of the Vhad and Vlad are slowly increased due to the existence of a capacitor, and the voltages of the Vhad and Vlad are increased to a stable state after a time T0, so that the collected Vhad and Vlad are considered to be effective only after a time T0 is waited after S1/S2/S6/S7 is closed;
after the time T0, the battery management system acquires VHad and Vlad voltage values, and the battery management system acquires VHad and Vlad voltage values and calculates positive electrode ground voltage VH and negative electrode ground voltage VL;
Figure BDA0004051506670000081
the VHad is a resistor R3 voltage value measured by the sampling circuit;
Figure BDA0004051506670000082
the VLad is a voltage value of a resistor R7 obtained by measuring a sampling circuit;
step S3: the insulation detection is in an initial state and is ready to enter a first state (at this time S1/S2/S6/S7 is closed, S3/S4/S5 is open);
vbat=vh+vl (formula 1-a);
Figure BDA0004051506670000083
wherein:
VBAT represents the terminal voltage of the power battery pack, rcircuit= (r2+r3), RCircuit' = (r6+r7) in equation 1-b; VH and VL are measured with relay S1 and relay S2 closed; since the resistance values (R2+R3) and (R6+R7) reach megaohms, VH and VL are assumed to be 250V, and the maximum value is the
Figure BDA0004051506670000084
=milliampere level, which can be processed to 0, because it is far smaller than the safe electric current of human body 2mA, which can be ignored, equation 1-b is processed to be publicized 1-c;
Figure BDA0004051506670000085
deducing:
Figure BDA0004051506670000086
step S4: the insulation detection ends the first state and prepares to enter the second state;
the control relay S3 is closed, and at this time, the voltages VHad and VLad are slowly increased due to the capacitor, so that it is necessary to wait for a period of time for the voltage to stabilize, and the measured value is accurate. In the normal running mode, only the capacitor Cy+ and Cy-are required to be charged, and in the fast charging mode, the Cy pile+ and Cy pile-are required to be charged in addition to the Cy+ to increase the voltage stabilizing time;
when the BMS recognizes that the vehicle is in a quick charge mode and waits for the time T1, the voltage is considered to be stable, the voltage values of VHad and VLad are collected for calculation, and the time T1 can be obtained through actual measurement;
after closing relay S3, after waiting for T1 time, VH' voltage is measured:
Figure BDA0004051506670000091
measuring VL' voltage:
Figure BDA0004051506670000092
wherein:
the positive ground voltage after closing the relay S3 is defined as VH ', and the negative ground voltage after closing the relay three S3 is defined as VL'; VHad' is the voltage sample value of resistor R3 after closing relay S3; VLad' is the voltage sample value of resistor R7 after closing relay S3;
from this, it can be seen that:
Figure BDA0004051506670000093
and (3) calculating a formula:
substituting formula 1-a and formula 1-d into formula 2-a; setting r0= (r2+r3)// r4, performing the operation results in:
Figure BDA0004051506670000094
further simplify:
Figure BDA0004051506670000095
further simplify:
Figure BDA0004051506670000096
further simplify:
Figure BDA0004051506670000097
substituting equation 1-d into equation 3-d yields further:
Figure BDA0004051506670000098
obtaining the resistance of the positive electrode to ground equivalent resistance Rp and the negative electrode to ground equivalent resistance Rn;
step S5: opening the relay S3, ending the second state of insulation detection, and preparing to enter a third state;
the relay S4 is closed, and the VHad and VLad voltages are slowly increased due to the capacitor, so that the measured value is accurate after a period of time for voltage stabilization is required. In the normal running mode, only the capacitor Cy+ and Cy-are required to be charged, and in the fast charging mode, the Cy pile+ and Cy pile-are required to be charged in addition to the Cy+ to increase the voltage stabilizing time;
when the BMS recognizes that the vehicle is in a quick charge mode and waits for the time T2, the voltage is considered to be stable, the voltage value of VHad/VLad is collected for calculation, and the time T2 can be obtained through actual measurement;
after closing relay S4, after waiting for T2 time, VH "measurements were made:
Figure BDA0004051506670000101
VL "measurements were made:
Figure BDA0004051506670000102
wherein:
the positive ground voltage after closing relay S4 is defined as VH ", and the negative ground voltage after closing relay S4 is defined as VL"; VHad "is the voltage sample value of the resistor R3 after closing the relay S4, VLad" is the voltage value of the resistor R7 after closing the relay S4;
from this, it can be seen that:
Figure BDA0004051506670000103
and (3) calculating a formula:
taking equations 1-a and 1-e into equations 2-b, let R0' = (R6+R7)// R8 perform the operation to obtain:
Figure BDA0004051506670000104
further simplify:
Figure BDA0004051506670000105
further simplify:
Figure BDA0004051506670000106
further simplify:
Figure BDA0004051506670000107
/>
it is possible to take equation 1-e into equation 4-d:
Figure BDA0004051506670000111
the resistance of the positive electrode to ground equivalent resistance Rp and the negative electrode to ground equivalent resistance Rn is obtained.
In summary, the smaller values of Rp and Rn, which are measured in the second state and the third state, are the insulation resistance values measured by the detection method.
While the invention has been described above by way of example with reference to the accompanying drawings, it is to be understood that the invention is not limited to the particular embodiments described, but is capable of numerous insubstantial modifications of the inventive concept and solution; or the invention is not improved, and the conception and the technical scheme are directly applied to other occasions and are all within the protection scope of the invention.

Claims (8)

1. The utility model provides an electric automobile self-adaptation insulation detection circuit which characterized in that, includes insulation resistance detection circuit, fills charge circuit soon and on-vehicle power circuit, fill charge circuit soon and insulation resistance detection circuit parallelly connected and with on-vehicle power circuit is connected, insulation resistance detection circuit is used for detecting on-vehicle power circuit's insulativity.
2. The electric automobile self-applicability insulation detection circuit according to claim 1, wherein the on-board power circuit comprises a power battery pack, a main positive relay S1, a main negative relay S2, a pre-charge resistor R1, a pre-charge relay S5 and a capacitor;
the main positive relay S1, the pre-charging resistor R1 and the pre-charging relay S5 are connected in series and are connected with the power battery VBat+, and the main negative relay S2 is connected with the negative electrode of the power battery;
the capacitor Cy+ is connected between the positive pole of the power battery and the ground, and the capacitor Cy-is connected between the power battery VBat-and the ground.
3. The electric vehicle self-adaptive insulation detection circuit according to claim 2, wherein the fast charging circuit comprises a fast charging positive contactor S6, a fast charging negative contactor S7, a direct current charging pile capacitor Cy pile+, a direct current charging pile capacitor Cy pile-and a direct current charging pile;
the positive pole of the direct current charging pile is connected with the main positive relay S1 through a fast charging positive pole contactor S6, and the negative pole of the direct current charging pile is connected with the main negative relay S2 through a fast charging negative pole contactor connection S7;
the direct-current charging pile capacitor Cy pile is connected between the positive electrode of the direct-current charging pile and the ground, and the direct-current charging pile capacitor Cy pile is connected between the negative electrode of the direct-current charging pile and the ground;
when the fast charging positive electrode contactor S6, the fast charging negative electrode contactor S7, the main positive relay S1 and the main negative relay S2 are all closed, the direct current charging pile is used for fast supplementing electricity to the power battery pack.
4. The self-adaptive insulation detection circuit for an electric automobile according to claim 1, wherein the insulation resistance detection circuit comprises three detection unit groups consisting of resistors R and relays S connected in parallel;
the first group of detection units are formed by connecting a resistor Rp and a resistor Rn in series and are connected with the power battery pack;
the resistor Rp is an equivalent resistor of the power battery pack VBat+ to the ground, and the resistor Rn is an equivalent resistor of the power battery pack VBat-to the ground, which is not an actual resistor;
the second group of detection units are formed by connecting a resistor R2, a resistor R3, a resistor R7 and a resistor R6 in series and are connected with the power battery pack;
a voltage acquisition point Vhad is connected between the resistor R2 and the resistor R3, and a voltage acquisition point Vlad is connected between the resistor R7 and the resistor R6;
the third group of detection units are formed by serially connecting a relay S3, a resistor R4, a resistor R8 and the relay S4 and are connected with the power battery pack.
5. The self-adaptive insulation detection circuit for an electric vehicle according to claim 3, wherein the insulation resistance detection circuit, the capacitor cy+, the capacitor Cy-, the dc charging stake capacitor Cy stake+ and the dc charging stake capacitor Cy stake-form an RC circuit;
the RC circuit has the functions of filtering and anti-interference on the insulation detection circuit.
6. The self-adaptive insulation detection circuit for an electric vehicle according to claim 2, wherein the power battery pack is composed of a plurality of power batteries.
7. The detection method of the self-adaptive insulation detection circuit for the electric automobile according to any one of claims 3 to 4, applied to a battery management system, comprising the steps of:
step S1: the quick-charging positive electrode contactor S6, the quick-charging negative electrode contactor S7, the main positive relay S1 and the main negative relay S2 are controlled to be closed, and the direct-current charging pile power battery pack is subjected to quick power charging;
step S2: setting a positive electrode grounding voltage VH and a negative electrode grounding voltage VL on an insulation resistance detection circuit, acquiring VHad and Vlad voltage values by a battery management system, and calculating to obtain the positive electrode grounding voltage VH and the negative electrode grounding voltage VL;
Figure QLYQS_1
the VHad is a resistor R3 voltage value measured by the sampling circuit;
Figure QLYQS_2
the VLad is a voltage value of a resistor R7 obtained by measuring a sampling circuit;
step S3: the insulation detection is in an initial state and is ready to enter a first state (at this time S1/S2/S6/S7 is closed, S3/S4/S5 is open);
vbat=vh+vl (formula 1-a);
Figure QLYQS_3
wherein:
VBAT represents the terminal voltage of the power battery pack, rcircuit= (r2+r3), RCircuit' = (r6+r7) in equation 1-b; VH and VL are measured with relay S1 and relay S2 closed
To (3) the point; since the resistance values (R2+R3) and (R6+R7) reach megaohms, VH and VL are assumed to be 250V, and the maximum value is the
Figure QLYQS_4
Can be processed to be 0, and can be ignored because the safe electric current of the human body is far smaller than 2mA, and the formula 1-b is processed to be 1-c;
Figure QLYQS_5
deducing:
Figure QLYQS_6
step S4: the insulation detection ends the first state and prepares to enter the second state;
control relay S3 closed, measure VH' voltage:
Figure QLYQS_7
measuring VL' voltage:
Figure QLYQS_8
wherein:
the positive ground voltage after closing the relay S3 is defined as VH ', and the negative ground voltage after closing the relay three S3 is defined as VL'; VHad' is the voltage sample value of resistor R3 after closing relay S3; VLad' is the voltage sample value of resistor R7 after closing relay S3;
from this, it can be seen that:
Figure QLYQS_9
and (3) calculating a formula:
substituting formula 1-a and formula 1-d into formula 2-a; setting r0= (r2+r3)// r4, performing the operation results in:
Figure QLYQS_10
further simplify:
Figure QLYQS_11
further simplify:
Figure QLYQS_12
further simplify:
Figure QLYQS_13
substituting equation 1-d into equation 3-d yields further:
Figure QLYQS_14
obtaining the resistance of the positive electrode to ground equivalent resistance Rp and the negative electrode to ground equivalent resistance Rn;
step S5: opening the relay S3, ending the second state of insulation detection, and preparing to enter a third state;
closing relay S4, making VH "measurements:
Figure QLYQS_15
VL "measurements were made:
Figure QLYQS_16
wherein:
the positive ground voltage after closing relay S4 is defined as VH ", and the negative ground voltage after closing relay S4 is defined as VL"; VHad "is the voltage sample value of the resistor R3 after closing the relay S4, VLad" is the voltage value of the resistor R7 after closing the relay S4;
from this, it can be seen that:
Figure QLYQS_17
and (3) calculating a formula:
taking equations 1-a and 1-e into equations 2-b, let R0' = (R6+R7)// R8 perform the operation to obtain:
Figure QLYQS_18
further simplify:
Figure QLYQS_19
further simplify:
Figure QLYQS_20
further simplify:
Figure QLYQS_21
it is possible to take equation 1-e into equation 4-d:
Figure QLYQS_22
the resistance of the positive electrode to ground equivalent resistance Rp and the negative electrode to ground equivalent resistance Rn is obtained.
8. The method of claim 7, wherein the insulation detects the second state and the insulation detects the smaller values of Rp and Rn that the third state measures.
CN202310043617.0A 2023-01-29 2023-01-29 Self-applicability insulation detection circuit and detection method for electric automobile Pending CN116047167A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117517906A (en) * 2024-01-02 2024-02-06 博最科技(苏州)有限公司 Insulation detection calculation method of self-adaptive Y capacitor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117517906A (en) * 2024-01-02 2024-02-06 博最科技(苏州)有限公司 Insulation detection calculation method of self-adaptive Y capacitor
CN117517906B (en) * 2024-01-02 2024-03-22 博最科技(苏州)有限公司 Insulation detection calculation method of self-adaptive Y capacitor

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