CN111830337B - Leakage detection method and leakage detection system - Google Patents
Leakage detection method and leakage detection system Download PDFInfo
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- CN111830337B CN111830337B CN202010490516.4A CN202010490516A CN111830337B CN 111830337 B CN111830337 B CN 111830337B CN 202010490516 A CN202010490516 A CN 202010490516A CN 111830337 B CN111830337 B CN 111830337B
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- 238000001514 detection method Methods 0.000 title claims abstract description 29
- 238000005259 measurement Methods 0.000 claims abstract description 16
- 238000011084 recovery Methods 0.000 claims description 13
- 238000000034 method Methods 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000005611 electricity Effects 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 230000032683 aging Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 230000008569 process Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
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- 244000038293 primary consumers Species 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/005—Testing of electric installations on transport means
- G01R31/006—Testing of electric installations on transport means on road vehicles, e.g. automobiles or trucks
- G01R31/007—Testing of electric installations on transport means on road vehicles, e.g. automobiles or trucks using microprocessors or computers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16566—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533
- G01R19/16571—Circuits and arrangements for comparing voltage or current with one or several thresholds and for indicating the result not covered by subgroups G01R19/16504, G01R19/16528, G01R19/16533 comparing AC or DC current with one threshold, e.g. load current, over-current, surge current or fault current
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
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Abstract
The invention provides a leakage detection method, which comprises the following steps: s1, counting deviation values related to current measurement precision in the electrical system; s2, calculating the sum of actual measurement currents of all branches in the electrical system; s3, comparing the sum of the currents with the deviation value, judging that the electric system has the electric leakage phenomenon if the sum of the currents is larger than the deviation value, otherwise, judging that the electric system is normal. The invention has the advantages that the components in the electric system can be effectively protected from damage, and the personal safety is not threatened, thereby improving the safety of the whole vehicle.
Description
Technical Field
The invention relates to the field of automobile control, in particular to a leakage detection method and a leakage detection system.
Background
In the automotive industry, a micro-hybrid powertrain is a relatively new powertrain that differs from a conventional powertrain by the addition of a 48V motor. The 48V motor provides power for the whole vehicle when the engine starts and stops and accelerates to assist; the 48V battery pack is charged by the generator when the engine rotates normally; and the engine can also recover power during braking, and can be converted into electric energy to be stored in a 48V battery pack.
The current 48V micro-hybrid power system mainly comprises a 48V motor, a 48V battery pack, a DC/DC module, a 48V load and other components. Since these components are dispersed in various locations throughout the vehicle, some are in the front cabin of the engine, some are under the cabin seat, and some are in the trunk, the components need to be connected by wiring harnesses. Over time, long-term operation of a vehicle in various environments will most likely lead to the phenomenon of aging of the insulation layer of the wire harness. And the aging of the wire harness insulating layer will cause the occurrence of electric leakage.
On the one hand, it is known that 48V dc is a critical safe voltage and is liable to cause damage to the human body.
On the other hand, when the 48V electrical network has the electricity leakage phenomenon, the electricity leakage current can cause short circuit to ground, and damage to parts.
In addition, the nature of electric leakage is also energy loss, that is to say, the energy recovery and boosting effect of the 48V electric system is greatly reduced, and if serious, the phenomenon of power shortage of the 48V battery can be caused, so that the electric energy management of the whole vehicle is influenced, and the energy among all the components in the system cannot be balanced.
Disclosure of Invention
In order to solve the problems, the electric leakage detection needs to be carried out on the 48V electric system, so that the influence on the 48V electric system and personal safety is reduced, safer and more reliable driving experience is brought to passengers.
The electric leakage detection method is used for detecting the electric leakage condition of an electric system and comprises the following steps:
s1, counting deviation values related to current measurement precision in the electrical system;
s2, calculating the sum of actual measurement currents of all branches in the electrical system;
S3, comparing the sum of the currents with the deviation value, judging that the electric system has the electric leakage phenomenon if the sum of the currents is larger than the deviation value, otherwise, judging that the electric system is normal.
In the above-mentioned leakage detection method, after the leakage phenomenon is determined, the power supply of the electrical system is interrupted and an alarm is given.
In the above-mentioned leakage detection method, the accuracy of any one of the branch currents is a product of an actual measurement value of the branch current and a measurement accuracy of the actual measurement value.
In the above-mentioned leakage detection method, in step S1, the precision deviation value is a square root of a sum of squares of the precision of each branch current.
In the above-mentioned leakage detection method, in step S2, the current flowing out of the power supply terminal is a positive value, and the currents of the other branches are negative values.
In the above-mentioned leakage detection method, in step S3, if the duration of the absolute value of the sum of the currents greater than the deviation value is greater than or equal to the preset time t, it is determined that a leakage phenomenon exists in the electrical system.
In the above-mentioned leakage detection method, each step is performed after the electrical system enters a stable operating state.
In the above leakage detection method, each branch is provided with a current sensor, and current data of each branch collected by the current sensor is uploaded through the bus.
Another object of the present invention is to provide an electrical leakage detecting system, which detects whether an electrical leakage phenomenon exists in the electrical system in real time according to the electrical leakage detecting method described in any one of the above.
The above-mentioned electric leakage detection system includes:
the electronic control unit is used for receiving the current data of each branch and judging whether the leakage phenomenon exists or not;
a battery management system for providing output current data of the battery;
The power-assisted recovery motor is used for providing current data of the power-assisted recovery motor; a load capable of providing self current data;
And the direct current converter provides the current value output by the direct current converter to the electronic control unit through the bus.
According to the technical scheme, the leakage condition of the electrical system is judged by comparing the precision deviation value and the closed loop current sum, if the leakage phenomenon is judged, the power supply of the electrical system is stopped, and the continuation of the leakage phenomenon is prevented, so that the components in the electrical system can be effectively protected from being damaged, the personal safety is not threatened, and the safety of the whole vehicle is ensured. Meanwhile, as the system can send out an alarm, maintenance personnel can check the electrical system in time so as to reduce the damage of parts caused by electric leakage, thereby avoiding unnecessary economic loss.
Drawings
FIG. 1 is a schematic circuit diagram of an embodiment of the present invention;
FIG. 2 is a system frame diagram of an embodiment of the present invention.
Detailed Description
In order to make the objects and features of the present application more comprehensible, embodiments accompanied with figures are described in detail below. This application may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Moreover, embodiments of the application and features of embodiments are allowed to be combined with or replaced with each other without conflict. The advantages and features of the present application will become more apparent in conjunction with the following description.
It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
It should be further noted that the step numbering in the present invention is for ease of reference, and not to limit the order of precedence. The steps of the respective order are emphasized, and will be specifically described in specific terms.
In micro-hybrid systems (particularly in the automotive field), 48V motors and 48V batteries are currently predominantly used. The 48V battery provides energy (mainly refers to large current) for the 48V motor when the vehicle starts, so that the 48V motor can actively output torque, the engine is helped to quickly increase the rotating speed, the starting time of the vehicle is shortened, and when the gasoline engine is connected to a power system, transition is gentle, and the situation of shaking of the vehicle is avoided.
Meanwhile, a 12V electrical system is arranged on the vehicle, and the voltage of the 48V battery can be reduced to 12V through the DC/DC module for the 12V system on the vehicle.
However, due to the critical safety of 48V direct current, once the electric leakage phenomenon occurs, the safety of people and vehicles is affected. Therefore, the invention aims to provide a technical scheme capable of timely finding out electric leakage and timely giving an alarm.
Based on kirchhoff's current law, let the current of the branch circuit containing the power output device in the closed loop be positive current, and the current of the other power consumption device branches be negative current, then the sum of the current of all the branches in the closed loop should be 0, namely in the closed loop:
Wherein I sum represents the absolute value of the sum of all the branch currents in the closed loop, I n represents the current value of each branch, and N is the number of branches.
In fact, however, even under normal conditions, the sum is typically a number close to 0 due to measurement errors.
On the other hand, from a statistical point of view, since the accuracy of the measured current of each branch is known, the accuracy deviation value of the closed loop can be calculated by a formula. Specifically, the deviation value may be calculated by the following equation 2:
Wherein I offset denotes the error range calculated from the measurement accuracy, I n denotes the current value of each branch, and f acn denotes the measurement accuracy of each branch.
In both aspects, the aforementioned floating range of the sum I sum approaching 0 due to measurement errors can be determined by the statistical accuracy deviation value I offset. That is, when the value of the sum is significantly beyond the calculated precision deviation value, it is considered that the 48V electrical system suffers from the leakage phenomenon.
Because the 48V electrical system is not an indispensable part for the running of the vehicle, the 48V electrical system can be commanded to be powered down after the electrical system of the vehicle judges that the 48V electrical system has the electric leakage phenomenon, thereby timely protecting the safety of people and vehicles.
As shown in fig. 1, the primary consumers of electricity in a 48V electrical system are shown, and these devices form a closed loop. In the figure, the 48V battery is the power output in a closed loop, and thus the current I mvb of this branch is labeled as positive. And if the current I mv_load of the 48V load branch is marked as a negative value, the current I brm of the power recovery motor branch needs to be treated differently, when the power recovery motor works in a power generation mode, the current I brm is marked as a positive value, and when the power recovery motor works in a motor mode, the current I brm is marked as a negative value, and the current I dcdc of the DC/DC conversion module branch is marked as a negative value. From the theory of kirchhoff's current law, it can be deduced from equation 1 that the sum of the currents I sum of the entire closed circuit shown in fig. 1 should be:
Isum＝|Imvb+Imv_load+Ibrm+Idcdc|＝0
In practice, the absolute value of I sum is a value close to 0.
Let the measurement accuracy of each branch in the graph be f mvb、fmv_load、fbrm and f dcdc respectively, then it can be deduced from equation 2 that the accuracy deviation value of the whole closed circuit shown in fig. 1 is:
After the specific values of the above-mentioned I sum and I offset are obtained, a comparison is made, if I sum>Ioffset, it is determined that there is a leakage phenomenon in the closed loop shown in fig. 1, the power supply of the 48V electrical system is required to be interrupted, and an alarm is sent to the driver and the passenger, requiring manual intervention and maintenance.
Further, in order to eliminate the influence of spike noise during the running process of the vehicle (because the noise is affirmative to cause erroneous judgment), the duration of I sum>Ioffset is monitored, i.e. when the system judges I sum>Ioffset, the operations of interrupting power supply, giving an alarm, etc. are not immediately performed, but whether I sum>Ioffset is continuously established is continuously judged and monitored. If I sum>Ioffset is only established once, the next determination result is no, then it can be considered that the former establishment of I sum>Ioffset is caused by external interference, but not a real leakage phenomenon. Specifically, a preset time t may be preset, and timing is started after the first determination that I sum>Ioffset is established, and if the continuous time t determines that I sum>Ioffset is established, then it is considered that the 48V electrical system has a leakage condition, and manual intervention and maintenance are required.
Further, each of the above steps is performed after the 48V electrical system enters a steady state operation. The stable operation state can be considered as a state that each controller in the 48V electrical system has completed initializing the safety self-checking process and begins to send a correct signal.
Fig. 2 is a system block diagram of a leakage detection system that may be used to implement the aforementioned leakage detection method. The figure includes an electronic control unit (ECU, electric Control Unit), a Battery management system (BMS, battery MANAGEMENT SYSTEM), a boost recovery motor (BRM, boost Recuperation Motor), a direct current converter (DC/DC), and a load capable of providing self current data.
Wherein, the current data between ECU, BMS, BRM, DC/DC and the load is exchanged through the bus.
Specifically, the ECU is a control unit, receives ECU, BMS, BRM, DC/DC and real-time current data provided by a load, calculates I sum and I offset according to a formula (1) and a formula (2), and then timely sends out an alarm according to a comparison result. The load is a direct load of a 48V electrical system, and the DC/DC converts the 48V voltage into 12V voltage for the 12V electrical system on the vehicle. Specifically, the alarm forms include lighting a trouble light on a console in a vehicle and an audible alarm.
After the ECU gives an alarm and cuts off the power supply of the 48V electrical system, the battery of the 12V electrical system still holds electric quantity, so that the work of the 12V electrical system (the power utilization of each electronic control device in the vehicle) is not influenced temporarily after the 48V electrical system is powered off, namely the control of the vehicle is not influenced temporarily, and the vehicle is stopped safely.
The electric leakage detection method and the electric leakage detection system ensure the safety of the 48V electric system on the vehicle, reduce unnecessary energy loss, simultaneously play a role in protecting each part in the 48V electric system, effectively reduce unnecessary cost caused by the damage of each part and improve the driving safety.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (8)
1. An electric leakage detection method for detecting an electric leakage condition of an electric system, the electric system including a power assist recovery motor, a battery, a dc converter, and a load, the power assist recovery motor, the battery, the dc converter, and the load forming a closed loop, characterized by comprising the steps of:
s1, counting the measurement precision of a power-assisted recovery motor branch, a battery branch, a direct current converter branch and a load branch, and obtaining a precision deviation value of the whole closed loop according to the measurement precision of each branch, wherein the precision deviation value is the square root of the sum of the squares of the products of the actual measurement value of each branch current and the measurement precision of the branch;
S2, calculating the current sum of the whole closed loop through the actual measured current of the power recovery motor branch, the actual measured current of the battery branch, the actual measured current of the direct current converter branch and the actual measured current of the load branch;
s3, comparing the current sum of the whole closed loop with the precision deviation value, judging that the electric system has the electric leakage phenomenon if the current sum of the whole closed loop is larger than the precision deviation value, otherwise, judging that the electric system is normal.
2. The leakage detection method according to claim 1, wherein after the leakage phenomenon is determined, the power supply of the electrical system is interrupted and an alarm is given.
3. The method of claim 1, wherein in step S2, the current flowing out of the power supply terminal is positive, and the currents of the other branches are negative.
4. The leakage detection method according to claim 1, wherein in step S3, if the duration of the absolute value of the sum of currents of the whole closed loop and the precision deviation value is greater than or equal to a preset time t, it is determined that there is a leakage phenomenon in the electrical system.
5. A leakage detection method according to claim 1, wherein said steps are performed after said electrical system has entered a steady state operation.
6. The leakage detection method according to claim 1, wherein each branch is provided with a current sensor, and current data of each branch collected by the current sensor is uploaded through a bus.
7. A leakage detection system, characterized in that the leakage detection method according to any one of claims 1 to 6 detects in real time whether or not a leakage phenomenon exists in the electrical system.
8. The electrical leakage detection system according to claim 7, comprising:
the electronic control unit is used for receiving the current data of each branch and judging whether the leakage phenomenon exists or not;
a battery management system for providing output current data of the battery;
The power-assisted recovery motor is used for providing current data of the power-assisted recovery motor; a load capable of providing self current data;
and the direct current converter provides the current value output by the direct current converter to the electronic control unit through a bus.
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| CN106199315A (en) * | 2016-08-31 | 2016-12-07 | 重庆长安汽车股份有限公司 | The hybrid power vehicle high voltage system leak current fault diagnostic equipment and method |
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| JP2010060329A (en) * | 2008-09-01 | 2010-03-18 | Patokkusu Japan Kk | Apparatus and method for measuring leakage current of electrical path and electric instrument |
| US8421444B2 (en) * | 2009-12-31 | 2013-04-16 | Schneider Electric USA, Inc. | Compact, two stage, zero flux electronically compensated current or voltage transducer employing dual magnetic cores having substantially dissimilar magnetic characteristics |
| KR20130028302A (en) * | 2011-09-09 | 2013-03-19 | 김보경 | On-line power cable insulation monitoring system and methods |
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| JP6709338B2 (en) * | 2017-05-30 | 2020-06-10 | 株式会社 シーディエヌ | Leakage detection method |
| CN209313420U (en) * | 2018-12-29 | 2019-08-27 | 苏州新丰综合能源服务有限公司 | A kind of family DC leakage monitoring for protection device |
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