CN116298451A - Current divider, current measurement method and battery system - Google Patents
Current divider, current measurement method and battery system Download PDFInfo
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- CN116298451A CN116298451A CN202310324672.7A CN202310324672A CN116298451A CN 116298451 A CN116298451 A CN 116298451A CN 202310324672 A CN202310324672 A CN 202310324672A CN 116298451 A CN116298451 A CN 116298451A
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- 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
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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
- G01R19/0092—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring current only
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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
- G01R19/32—Compensating for temperature change
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- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The invention discloses a current divider, a current measurement method and a battery system, wherein the current divider comprises a direct current divider body (1); the left end and the right end of the top of the direct current shunt body (1) are respectively provided with a metal terminal component (102); each metal terminal part (102) is respectively connected with one power fixing screw (3) and one signal fixing screw (4); a current detection resistor (100) is arranged in the middle of the direct current shunt body (1); the top surface of the current detection resistor (100) is connected with the bottom surface of the thermistor; the thermistor is connected with a signal acquisition end of an external temperature acquisition plate through a thermistor lead wire on the thermistor. The current divider, the current measurement method and the battery system can effectively reduce the influence of temperature change of the current detection resistor (namely the metal alloy component) on the current value measurement precision of the current divider and improve the current value sampling precision.
Description
Technical Field
The invention relates to the technical field of current detection of new energy battery systems, in particular to a current divider, a current measurement method and a battery system.
Background
At present, a power battery system needs to detect a charge-discharge current value, and in order to control the cost, a current divider is generally selected to detect the charge-discharge current value of the power battery system. The shunt is an instrument for measuring direct current and is manufactured according to the principle that voltage is generated at two ends of a resistor when direct current passes through the resistor.
In the application of the current divider, a larger current is applied to the resistor body (i.e., the current detection resistor) of the current divider, and in view of the fact that the resistor generates heat due to continuous loading, the resistance value of the current divider is affected by temperature change, so that a resistance alloy with a lower temperature coefficient is generally used for preparing the current detection resistor.
However, due to the influence of the manufacturing process of the current detection resistor or the copper electrode provided on the current detection resistor, the temperature coefficient of the finished product of the current detection resistor tends to change to a certain extent compared with that of the base metal alloy, for example, the temperature coefficient is larger, and thus the current detection resistor is easily influenced by the temperature change, and the measurement precision of the current value of the current divider is lower.
In view of the above, in practical use, there is a strong need to develop a technique for effectively reducing the influence of temperature variation on the current measurement accuracy of the shunt.
Disclosure of Invention
The invention aims at overcoming the technical defects existing in the prior art and provides a current divider, a current measuring method and a battery system.
To this end, the invention provides a shunt comprising a dc shunt body;
the left and right ends of the top of the direct current shunt body are respectively provided with a metal terminal component;
each metal terminal part is respectively connected with one power fixing screw and one signal fixing screw;
the middle part of the direct current shunt body is provided with a current detection resistor;
the top surface of the current detection resistor is connected with the bottom surface of the thermistor;
the thermistor is connected with a signal acquisition end of an external temperature acquisition plate through a thermistor lead wire on the thermistor.
In addition, the invention also provides a battery system which comprises a battery module and the current divider;
the positive electrode of the battery module is connected with the positive electrode of the load;
a negative electrode of the battery module through a negative electrode of the load;
two power fixing screws in the shunt are respectively connected with the negative electrode of the battery module and the negative electrode of the load;
and two signal fixing screws in the shunt are used for connecting two voltage testing ends on external voltage acquisition equipment.
In addition, the invention also provides a current measurement method using the shunt, which comprises the following steps:
step S1, connecting two power fixing screws in a shunt with a negative electrode of a battery module and a negative electrode of a load respectively, connecting two signal fixing screws in the shunt with two voltage testing ends on external voltage acquisition equipment, and acquiring voltage values of two ends of a current detection resistor in the shunt through the external voltage acquisition equipment;
wherein, the positive pole of the battery module is connected with the positive pole of the load;
s2, collecting the current temperature of a current detection resistor through a thermistor connected with an external temperature collection plate;
step S3, obtaining the resistance value of the current detection resistor at the current temperature according to the resistance value of the current detection resistor at the reference temperature and the temperature drift coefficient of the resistor;
and step S4, obtaining the current value flowing through the shunt according to the resistance value of the current detection resistor at the current temperature obtained in the step S3 and the voltage value of the two ends of the current detection resistor obtained in the step S1.
Compared with the prior art, the invention has the following beneficial effects:
the current temperature of the current detection resistor is acquired through the film thermistor (NTC) connected with the external temperature acquisition plate, and then the resistance value at the current temperature is obtained according to the resistance value of the current detection resistor at the reference temperature and the temperature drift coefficient of the resistor, so that the resistance value of the current detection resistor at the current temperature is obtained through calculation according to the resistance value of the current detection resistor at the reference temperature and the temperature drift coefficient of the resistor, and then the current value flowing through the current detection resistor is finally obtained according to the resistance value of the current detection resistor at the current temperature and the voltage values at two ends of the current detection resistor acquired through two signal fixing screws connected with external voltage acquisition equipment.
The current divider, the current measurement method and the battery system effectively solve the problem that the current detection precision of the current divider is reduced due to the temperature change of the metal alloy (namely the alloy for the current detection resistor) of the current divider in the prior art, and meanwhile, an outer shell is not required to be additionally designed.
The current divider and the battery system provided by the invention can monitor the temperature of the power fixing screw, judge that the connection is abnormal when the temperature is abnormal, report the fault, and perform maintenance treatment, so that the temperature of the current detection resistor is prevented from being influenced by abnormal temperature change, and the sampling precision is prevented from being reduced.
According to the shunt and the battery system, the threaded fastening glue is coated between the signal fixing screw and the metal terminal component, so that the influence on the sampling value of the voltage at the two ends of the direct current shunt body caused by loosening of threaded connection between the signal fixing screw and the metal terminal component can be avoided, and the sampling precision of the resistance value of the final current detection resistor is further influenced.
The current divider and the battery system provided by the invention can more effectively lead out the heat on the current detection resistor, so that the heat conduction and heat dissipation effects are better, and the influence of temperature change on measurement accuracy is further reduced.
The shunt provided by the invention can have various different specifications and sizes, and has strong applicability.
Drawings
Fig. 1 is a schematic structural diagram of a diverter connected to a battery box according to the present invention;
fig. 2 is a schematic structural diagram of a dc shunt body according to the present invention;
FIG. 3 is a schematic diagram of the connection between a current divider and a battery system and a load according to the present invention;
in the figure: 1. a DC shunt body; 2. a thin film thermistor (NTC); 3. a power set screw; 4. a signal fixing screw; 5. thread fastening glue;
6. a thermal pad; 7. a heat-conducting adhesive; 8. a battery case;
11. a toroidal thermistor (NTC); 21. a thermistor (NTC) lead; 22. a heat-conducting double-sided adhesive tape;
111. a toroidal thermistor (NTC) lead;
100. a current detection resistor; 101. a power fixing screw threaded hole; 102. a metal terminal member.
P, load.
Detailed Description
The technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first", "a second", etc. may explicitly or implicitly include one or more such feature. In the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art in a specific case.
The invention will be described in detail below with reference to the drawings in connection with embodiments.
Referring to fig. 1 to 3, the present invention provides a current divider applied to a battery system, and specifically includes a dc current divider body 1;
the left and right ends of the top of the direct current shunt body 1 are respectively provided with a metal terminal part 102;
each metal terminal part 102 is connected with one power fixing screw 3 and one signal fixing screw 4 respectively; the concrete structure is as follows: each metal terminal part 102 is respectively provided with a power fixing screw threaded hole 101; the power fixing screw 3 is used for outputting the current of the battery module to the copper bar fixing metal terminal part 102 and realizing the insulation connection between the current divider and the bottom of the battery box body 8;
the middle part of the direct current shunt body 1 is provided with a current detection resistor 100;
the top surface of the current detection resistor 100 is connected with the bottom surface of the thermistor;
the thermistor is connected with a signal acquisition end of an external temperature acquisition board through a thermistor lead wire 21 on the thermistor.
The thermistor is preferably a thin film thermistor (NTC) 2.
Since the temperature has a great influence on the resistance value of the current detection resistor 100 (i.e., the metal alloy component) of the shunt, that is, a certain temperature drift exists, the accuracy of the sampled current value is affected after the resistance value changes. Therefore, the temperature of the current detection resistor 100 (i.e. metal alloy component) is collected by using the thin film thermistor (NTC) 2, the thin film thermistor (NTC) 2 is tightly adhered to the metal alloy part (i.e. the current detection resistor 100) of the direct current shunt body 1 by using the heat conducting double faced adhesive tape 22, and is connected with the external temperature collection board through the thermistor lead 21, the resistance value of the external temperature collection board for the thin film thermistor is processed according to the temperature characteristic table (RT table), converted into the current temperature value and used as the current temperature of the current detection resistor 100, and then the collected resistance value of the current detection resistor 100 (i.e. the metal alloy component) can be corrected to the theoretical resistance value at the current temperature according to the resistance values (i.e. the theoretical temperature drift value, the physical parameter of the resistor) or the resistance temperature drift coefficient TCR of the current detection resistor 100 at different temperature values, and the current value flowing through the current detection resistor 100 can be corrected by correcting the resistance value of the current detection resistor 100 due to the current i=voltage U/resistor R.
The resistance will change with temperature. The ratio of the resistance to the temperature change is called the temperature coefficient of resistance (also called the temperature drift coefficient TCR), that is, the change of the resistance value caused by the unit temperature, specifically refers to the change degree of the resistivity of the resistor per degree celsius when the temperature rises or drops, and is physically defined as the expansion coefficient of the resistive material.
The temperature coefficient of resistance (also referred to as the temperature coefficient of resistance) is in ppm/. Degree.C. From the resistance change rate and the temperature difference under the reference temperature condition, the resistance temperature coefficient of the resistor can be obtained by the following formula, that is, in step S3, the resistance value of the flow detection resistor 100 at the current temperature can be calculated by the following formula:
temperature coefficient of resistance tcr= (R-Ra)/Ra ++ (T-Ta) ×1000000 in ppm/°c;
in the above formula, ra is the resistance of the resistor under the condition of the reference temperature, ta is the reference temperature, R is the resistance of the resistor under the condition of any temperature, and T is any temperature.
The thin film thermistor (NTC) 2 is adhered to the current sensing resistor 100 (i.e., metal alloy part) of the shunt using the heat conductive double sided tape 22, and has the following advantages:
the heat-conducting double-sided tape 22 has high heat conduction and insulation characteristics, has adhesion and adhesiveness, and can enable the film thermistor (NTC) 2 to be tightly attached to the current detection resistor 100, so that the temperature on the current detection resistor 100 during overcurrent is effectively collected.
In the invention, each metal terminal part 102 is respectively provided with a power fixing screw threaded hole 101;
the top of each metal terminal member 102 is connected to the lower end of one power set screw 3, respectively.
In the concrete implementation of the invention, each power fixing screw 3 is respectively positioned at the inner side of an annular terminal at one end of an annular thermistor 11;
the annular terminals of the two annular thermistors 11 are respectively arranged at the top of the two metal terminal parts 102, specifically at the peripheral edges of the power fixing screw threaded holes 101 arranged on the metal terminal parts 102.
Preferably, the annular thermistor 11 is connected to the signal acquisition end of the external temperature acquisition board by an annular thermistor lead 111 thereon.
In the present invention, the annular thermistor (NTC) 11 is welded to the periphery of the power fixing screw hole 101 of the shunt by laser welding, and the annular thermistor (NTC) 11 and the dc shunt body 1 together can constitute a new shunt device.
It should be noted that, for the present invention, the NTC resistance value collected by the annular thermistor (NTC) 11 may be led out to an external temperature collection board through the annular thermistor lead 111, where the external temperature collection board is used for collecting and processing temperature data; if the temperature rise of the installation part of the annular thermistor (NTC) 11 is abnormal due to loosening of the power fixing screw 3, the external temperature acquisition plate can act to control and cut off the current loop of the shunt.
The metal terminal part 102 is also provided with a signal fixing screw threaded hole, and the metal terminal part 102 is in threaded connection with the lower end of the signal fixing screw 4 through the signal fixing screw threaded hole;
the signal fixing screw 4 is connected to an external voltage collecting device, such as a direct current voltmeter or a battery management system BMS, to obtain the voltage values of both ends of the current detecting resistor 100.
In the invention, the screw thread fastening glue 5 is smeared on the screw thread connecting part of the signal fixing screw 4 and the metal terminal part 102, so that the influence on the sampling precision of the resistance value caused by the loosening of the screw thread connecting between the signal fixing screw 4 and the metal terminal part 102 can be prevented.
The bottom surface of the current detection resistor 100 (i.e. the metal alloy part) in the direct current shunt body 1 is contacted with the top surface of the heat conduction pad 6;
the bottom surface of the heat conducting pad 6 is adhered to the top of the battery box body 8 positioned outside through the heat conducting adhesive 7.
The current detection resistor 100 (i.e., metal alloy member) can conduct heat of the current detection resistor 100 (i.e., metal alloy member) to the battery case 8 through the heat conductive pad 6. The heat conduction glue 7 is arranged between the heat conduction pad 6 and the battery box body 8, the heat conduction glue 7 not only plays a role in fixing, but also can more effectively conduct out heat on the current detection resistor 100 due to the fact that the area of the battery box body 8 is larger and is in good contact with external air, and therefore better heat conduction and heat dissipation effects are achieved.
The dc shunt body 1 of the present invention may be a metal alloy shunt for current detection based on resistance, which is commonly used in the market at present. This is a well-known electronic component that is mature in the prior art and will not be described in detail herein.
The thin film thermistor (NTC) 2 of the present invention is preferably a thin film thermistor that has high mechanical strength, high induction speed, and good environmental reliability, and is authenticated by AEC-Q200.
The annular thermistor (NTC) 11 in the present invention, in particular a thermistor (NTC) with an annular terminal, i.e. also commonly referred to as OT terminal; the ring terminal is welded to the peripheral edge of the power set screw threaded hole 101.
The annular thermistor (NTC) 11 is preferably an OT annular thermistor which meets the requirement of screw holes by specification and size, has high mechanical strength, high induction speed and good environmental reliability and passes the authentication of AEC-Q200; the OT annular NTC can be adjusted according to the size of the diverter mounting threaded hole; the OT annular NTC is fixed at the power fixing screw threaded hole of the shunt in a laser welding mode and is responsible for collecting the temperature of the connection position of the power fixing screw and the copper bar of the battery module and the temperature of the metal terminal part 102, and when the temperature is abnormal, the connection is judged to be abnormal, the fault is reported, and the maintenance treatment is carried out. The heat generation at the time of overcurrent due to loosening of the screw connection is prevented from being serious, and thus abnormal change of the temperature at the metal alloy part (i.e., the current detection resistor 100) is affected.
The dc shunt body 1 of the present invention is preferably a resistor body welded by electron beam of manganese copper alloy.
The fixing screw in the invention is preferably a screw which meets national standard requirements and meets the installation requirement specification of the shunt. The fixing screws are divided into a power fixing screw 3 and a signal fixing screw 4, wherein the power fixing screw 3 is in threaded connection with a reserved threaded hole on an external battery system current output copper bar and a power fixing screw threaded hole 101 on a metal terminal part 102 of the shunt (the battery system current output copper bar is positioned between a nut of the power fixing screw 3 and the metal terminal part 102, and the power fixing screw 3 vertically penetrates through the threaded hole on the copper bar), so that the battery system current output copper bar and the shunt are fixed together, and accordingly, the current output by the battery system flows through the shunt through the copper bar. The signal fixing screw 4 is screwed into a corresponding threaded hole provided in the metal terminal member 102 (i.e., as a member for collecting the voltage across the dc shunt body).
The grain fastening glue 5 in the invention is preferably a detachable locking glue, and can be used for detaching a workpiece by using a hand tool.
The heat conduction pad 6 in the invention is preferably a heat conduction pad with the heat conduction coefficient more than or equal to 1.5W/mk, the insulation withstand voltage meeting 3000VAC and the leakage current less than 1 mA; the thermal pad may vary according to different dimensional variations of the shunt;
the heat conducting glue 7 in the invention is preferably electric insulating glue; the heat conducting pad 6 and the heat conducting glue 7 can ensure the normal insulation value of the system.
The current temperature of the current detection resistor 100 is acquired through the film thermistor (NTC) 2 connected with the external temperature acquisition plate, and then the resistance value at the current temperature is obtained according to the resistance value of the current detection resistor at the reference temperature and the resistance temperature drift coefficient, so that the resistance value of the current detection resistor 100 at the current temperature is calculated according to the resistance value of the current detection resistor 100 at the reference temperature and the resistance temperature drift coefficient, and then the current value flowing through the current detection resistor 100 is finally obtained according to the resistance value of the current detection resistor 100 at the current temperature and the voltage values at two ends of the current detection resistor 100 acquired through two signal fixing screws connected with external voltage acquisition equipment.
The current divider provided by the invention effectively solves the problem of current detection accuracy reduction of the current divider caused by temperature change of the metal alloy (namely the alloy for the current detection resistor) of the current divider in the prior art, and meanwhile, an outer shell is not required to be additionally designed.
The current divider provided by the invention can monitor the temperature of the power fixing screw 3, judge that the connection is abnormal when the temperature is abnormal, report faults, carry out maintenance treatment, avoid the influence of abnormal temperature change on the temperature of the current detection resistor 100 (namely, the metal alloy part, namely, the metal alloy part) and prevent the reduction of sampling precision.
Meanwhile, the shunt provided by the invention is characterized in that the screw thread fastening glue 5 is coated between the signal fixing screw 4 and the metal terminal part 102, so that signal sampling connection is stabilized, and the influence on the sampling value of the voltage at two ends of the direct current shunt body 1 due to loosening of the screw thread connection between the signal fixing screw 4 and the metal terminal part 102 is avoided, and then the sampling precision of the resistance value of the final current detection resistor 100 is influenced.
In addition, referring to fig. 1 and 3, the present invention also provides a battery system including a battery module (battery) and a current divider as described above;
the positive electrode of the battery module is connected with the positive electrode of the load P;
the negative electrode of the battery module is connected with the negative electrode of the load through a shunt;
two power fixing screws 3 in the shunt are respectively connected with the negative electrode of the battery module and the negative electrode of the load;
and two signal fixing screws 4 in the shunt are used for connecting two voltage testing ends on external voltage acquisition equipment.
The battery system also comprises a battery box body 8, wherein the battery module and the current divider are both positioned in the battery box body 8, and the current divider is positioned between the battery module and the bottom of the battery box body 8;
preferably, the current divider is connected with the battery box 8 in an insulating manner by an insulator.
Specifically, the negative electrode lead wire (such as a current output copper bar) of the battery module is connected to the power fixing screw of the current divider, and the power fixing screw is connected with the bottom of the battery box 8 in an insulating manner through an insulator.
The load refers to a device for receiving electric energy in a circuit, and is a generic term for various electric appliances. For example, common loads are power-consuming components such as resistors, light bulbs, air conditioners, motors, and the like.
The insulator is a device which is mounted between conductors of different electric potentials or between a conductor and a ground member and can withstand voltage and mechanical stress, and is a conventional device known in the art. For example, insulators are classified by structure, and may be classified into column insulators, suspension insulators, pin insulators, butterfly insulators, tension insulators, anti-fouling insulators, sleeve insulators, and the like. In addition, insulators are classified into porcelain insulators, glass insulators, composite insulators, and the like according to the insulating materials used.
Fig. 3 is a schematic diagram showing a connection relationship between a current divider and a battery module and a load located outside according to the present invention; the battery module (battery) is used for providing working electricity for the load (P), the positive electrode of the battery module is connected with the positive electrode of the load (P), and the negative electrode of the battery module is connected with the negative electrode of the load (P) through the current divider provided by the invention. Wherein, the negative electrode of the battery module (battery) and the negative electrode of the load (P) are respectively connected with the power fixing screw 3 on one metal terminal part 102 of the direct current shunt body 1;
referring to fig. 3, two voltage test terminals (ISENSEL) of a Battery Management System (BMS) may be specifically connected to two signal fixing screws 4 on two metal terminal parts 102 of the dc shunt body 1;
referring to fig. 3, the current divider of the present invention is disposed between the negative electrode of the battery module (battery) and the negative electrode of the load (P), the current output by the battery module flows through the current detection resistor 100 (i.e., the metal alloy component) in the dc current divider body 1, the metal alloy component has a certain resistance value, the battery management system BMS collects the voltage values at two ends of the current detection resistor 100 (i.e., the metal alloy component) according to the voltage calculation formula u=ir, and the current value flowing through the current divider can be estimated according to the voltage values and the resistance value of the metal alloy component.
In addition, the invention also provides a measuring method of the diverter, which comprises the following steps:
step S1, connecting two power fixing screws 3 in a shunt with a negative electrode of a battery module and a negative electrode of a load respectively, connecting two signal fixing screws 4 in the shunt with two voltage testing ends on external voltage acquisition equipment, and acquiring voltage values of two ends of a current detection resistor 100 in the shunt through the external voltage acquisition equipment;
wherein, the positive pole of the battery module is connected with the positive pole of the load;
step S2, collecting the current temperature of the current detection resistor 100 (namely, the metal alloy component) through a film thermistor 2 (NTC) connected with an external temperature collection plate;
step S3, obtaining the resistance value of the current detection resistor 100 at the current temperature according to the resistance value (for example, the resistance value of 25 ℃ is the nominal value) of the current detection resistor 100 at the reference temperature and the resistance temperature drift coefficient;
all substances have a resistance value which changes with a change in temperature. The resistor is not exceptional, and the resistance value changes with temperature. The change ratio of the resistance is called a temperature coefficient of resistance (also called a temperature drift coefficient TCR of resistance), that is, the change of the resistance value caused by a unit temperature, specifically refers to the change degree of the resistivity of the resistance per degree celsius when the temperature rises or drops, and is physically defined as the expansion coefficient of the resistance material.
The temperature coefficient of resistance (also referred to as the temperature coefficient of resistance) is in ppm/. Degree.C. From the resistance change rate and the temperature difference under the reference temperature condition, the resistance temperature coefficient of the resistor can be obtained by the following formula, that is, in step S3, the resistance value of the flow detection resistor 100 at the current temperature can be calculated by the following formula:
temperature coefficient of resistance tcr= (R-Ra)/Ra ++ (T-Ta) ×1000000 in ppm/°c;
in the above formula, ra is the resistance of the resistor under the condition of the reference temperature, ta is the reference temperature, R is the resistance of the resistor under the condition of any temperature, and T is any temperature.
Step S4, obtaining a current value flowing through the shunt, that is, a measurement result of the shunt, according to the resistance value of the current detection resistor 100 at the present temperature obtained in step S3 and the voltage values of both ends of the current detection resistor 100 obtained in step S1. Therefore, accuracy correction of the measured current value of the shunt is realized, and degradation of the shunt current detection accuracy due to temperature change of the metal alloy of the shunt (i.e., the alloy for the current detection resistor) is avoided.
The current value flowing through the shunt is calculated by dividing the voltage value across the current detection resistor 100 by the resistance value of the current detection resistor 100 at the present temperature.
According to the invention, by means of reducing adverse temperature influence, preventing additional resistance superposition, effectively radiating generated heat and the like, the influence of temperature change on the sampling precision of the shunt in a natural cooling system is effectively reduced, and the use precision of the shunt is improved.
In summary, the design of the current divider, the current measurement method and the battery system provided by the invention is scientific, the current temperature of the current detection resistor is collected through the film thermistor (NTC) connected with the external temperature collection plate, and then the resistance value at the current temperature is obtained according to the resistance value of the current detection resistor at the reference temperature and the resistance temperature drift coefficient, so that the resistance value of the current detection resistor at the current temperature is obtained through calculation according to the resistance value of the current detection resistor at the reference temperature and the resistance temperature drift coefficient, and then the current value flowing through the current divider is finally obtained according to the resistance value of the current detection resistor at the current temperature and the voltage values at two ends of the current detection resistor collected through two signal fixing screws connected with external voltage collection equipment, therefore, the influence of the temperature change of the current detection resistor (namely the metal alloy component) on the current value measurement precision of the current divider is effectively reduced, the current value sampling precision of the current divider is improved, and the current value sampling precision of the current divider is significant.
The current divider, the current measurement method and the battery system effectively solve the problem that the current detection precision of the current divider is reduced due to the temperature change of the metal alloy (namely the alloy for the current detection resistor) of the current divider in the prior art, and meanwhile, an outer shell is not required to be additionally designed.
The current divider and the battery system provided by the invention can monitor the temperature of the power fixing screw, judge that the connection is abnormal when the temperature is abnormal, report the fault, and perform maintenance treatment, so that the temperature of the current detection resistor is prevented from being influenced by abnormal temperature change, and the sampling precision is prevented from being reduced.
According to the shunt and the battery system, the threaded fastening glue is coated between the signal fixing screw and the metal terminal component, so that the influence on the sampling value of the voltage at the two ends of the direct current shunt body caused by loosening of threaded connection between the signal fixing screw and the metal terminal component can be avoided, and the sampling precision of the resistance value of the final current detection resistor is further influenced.
The current divider and the battery system provided by the invention can more effectively lead out the heat on the current detection resistor, so that the heat conduction and heat dissipation effects are better, and the influence of temperature change on measurement accuracy is further reduced.
The shunt provided by the invention can have various different specifications and sizes, and has strong applicability. The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A shunt, characterized by comprising a direct current shunt body (1);
the left end and the right end of the top of the direct current shunt body (1) are respectively provided with a metal terminal component (102);
each metal terminal part (102) is respectively connected with one power fixing screw (3) and one signal fixing screw (4);
a current detection resistor (100) is arranged in the middle of the direct current shunt body (1);
the top surface of the current detection resistor (100) is connected with the bottom surface of the thermistor;
the thermistor is connected with a signal acquisition end of an external temperature acquisition plate through a thermistor lead wire on the thermistor.
2. The shunt of claim 1, wherein said thermistor is a thin film thermistor;
preferably, the top surface of the current detection resistor (100) is adhered to the film thermistor through a heat-conducting double-sided adhesive tape (22).
3. The shunt of claim 1 wherein said each metal terminal member (102) is provided with a power set screw threaded bore (101) and a signal set screw threaded bore;
each metal terminal part (102) is respectively in threaded connection with the power fixing screw (3) and the signal fixing screw (4) through the power fixing screw threaded hole (101) and the signal fixing screw threaded hole.
4. A shunt according to claim 1, characterized in that each power set screw (3) is located inside a ring terminal at one end of a ring thermistor (11);
the ring terminals of the two ring thermistors (11) are respectively arranged on the tops of the two metal terminal parts (102).
5. The shunt of claim 4 wherein said annular thermistor (11) is connected to a signal acquisition terminal of an external temperature acquisition board by an annular thermistor lead (111) thereon.
6. Shunt according to claim 1, characterized in that the connection of the metal terminal part (102) with the signal fixing screw (4) is provided with a thread tightening glue (5).
7. The shunt of claim 1 wherein said current sensing resistor (100) bottom surface is bonded to said heat conducting pad (6) top surface by a heat conducting glue;
the bottom surface of the heat conducting pad (6) is adhered with the battery box body (8) through heat conducting glue.
8. A battery system comprising a battery module and the shunt according to any one of claims 1 to 7;
the positive electrode of the battery module is connected with the positive electrode of the load;
the negative electrode of the battery module is connected with the negative electrode of the load through a shunt;
two power fixing screws (3) in the shunt are respectively connected with the negative electrode of the battery module and the negative electrode of the load;
and two signal fixing screws (4) in the shunt are used for connecting two voltage testing ends on external voltage acquisition equipment.
9. The battery system of claim 8, further comprising a battery housing (8), wherein the battery module and the current divider are both located in the battery housing (8), and wherein the current divider is located between the battery module and the bottom of the battery housing (8);
preferably, the current divider is connected with the battery box (8) in an insulating way through an insulator.
10. A current measurement method using the shunt according to any one of claims 1 to 7, characterized by comprising the steps of:
step S1, connecting two power fixing screws (3) in a shunt with a negative electrode of a battery module and a negative electrode of a load respectively, connecting two signal fixing screws (4) in the shunt with two voltage testing ends on external voltage acquisition equipment, and acquiring voltage values of two ends of a current detection resistor (100) in the shunt through the external voltage acquisition equipment;
wherein, the positive pole of the battery module is connected with the positive pole of the load;
s2, collecting the current temperature of a current detection resistor (100) through a thermistor connected with an external temperature collection plate;
step S3, obtaining the resistance value of the current detection resistor (100) at the current temperature according to the resistance value of the current detection resistor (100) at the reference temperature and the resistance temperature drift coefficient;
and step S4, obtaining the current value flowing through the shunt according to the resistance value of the current detection resistor (100) at the current temperature obtained in the step S3 and the voltage value of the two ends of the current detection resistor (100) obtained in the step S1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310324672.7A CN116298451A (en) | 2023-03-29 | 2023-03-29 | Current divider, current measurement method and battery system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310324672.7A CN116298451A (en) | 2023-03-29 | 2023-03-29 | Current divider, current measurement method and battery system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116298451A true CN116298451A (en) | 2023-06-23 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310324672.7A Pending CN116298451A (en) | 2023-03-29 | 2023-03-29 | Current divider, current measurement method and battery system |
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| Country | Link |
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| CN (1) | CN116298451A (en) |
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2023
- 2023-03-29 CN CN202310324672.7A patent/CN116298451A/en active Pending
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