WO2021161237A1 - Procédé de prédiction de comportement de résistance thermique de shunts - Google Patents

Procédé de prédiction de comportement de résistance thermique de shunts Download PDF

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Publication number
WO2021161237A1
WO2021161237A1 PCT/IB2021/051168 IB2021051168W WO2021161237A1 WO 2021161237 A1 WO2021161237 A1 WO 2021161237A1 IB 2021051168 W IB2021051168 W IB 2021051168W WO 2021161237 A1 WO2021161237 A1 WO 2021161237A1
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WIPO (PCT)
Prior art keywords
shunt
region
temperature
sensing points
resistance
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Ceased
Application number
PCT/IB2021/051168
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English (en)
Inventor
Nicolas CLAUVELIN
Victor Marten
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Sensata Technologies Inc
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Sendyne Corp
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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K1/00—Details of thermometers not specially adapted for particular types of thermometer
    • G01K1/14—Supports; Fastening devices; Arrangements for mounting thermometers in particular locations
    • G01K1/143—Supports; Fastening devices; Arrangements for mounting thermometers in particular locations for measuring surface temperatures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
    • G01R1/20—Modifications of basic electric elements for use in electric measuring instruments; Structural combinations of such elements with such instruments
    • G01R1/203—Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
    • G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references

Definitions

  • the invention relates to the general goal of accurate current measurements in a shunt, with the measurements being accurate at any of a range of temperatures of the shunt, while minimizing the number of calibration measurements that were previously needed to bring about the desired level of accuracy.
  • the main resistive element of the shunt is constructed by a strip of manganin, or another alloy with similar properties, which is welded to copper plates on both sides. Measurement points are created via any of several methods (welding, inserted pins, soldered pins, direct soldering on PCB or copper extrusions) to provide connections with the measurement circuit electronics.
  • Manganin (or a material with similar properties) exhibits a much higher specific resistance than copper, so its utilization contributes to a smaller overall size for a shunt of a given resistance value.
  • manganin has a very low temperature coefficient, so its resistance value changes veiy little with temperature.
  • Figure 2 shows a typical temperature coefficient of resistence for manganin. The alert reader appreciates that the vertical axis is stretched, and that over wide ranges of temperature the curve shown is actually veiy close to being flat. Copper is a very good conductor of both electricity and heat and its main contribution in the shunt utilization is the efficient dissipation of heat without any significant contribution toward the generation of heat.
  • a typical dependency of resistivity upon temperature for copper is depicted in Figure 3.
  • Typical values for high current shunts such as are being discussed herein are in the range of 10s or 100s of mW.
  • Measurements of large currents are difficult.
  • Various techniques are typically utilized, including sensing of magnetic field around the conductor (for example Hall-effect-based instruments and the like), and measurements based on the voltage drop across a known resistor (shunt).
  • the former method has some specific advantages, one of then being the relative insensitivity to external magnetic fields. Indeed a shunt-base current measurement system is often preferred over other methods.
  • a typical shunt is constructed from two different materials: a first material is made from a “proper” resistive material with very small TCR (Temperature Coefficient of Resistance), and a second material with high conductance (typically copper) is used for the terminals of the shunt, for connection into the circuit.
  • TCR Temporal Coefficient of Resistance
  • a second material with high conductance typically copper
  • the dissimilar materials are attached (mechanically and electrically) to each other with welding, with electron-beam welding often used for the creation of strong and well-defined (narrow) weld lines.
  • Such weld lines are pointed out in Figure 4.
  • the exact dimensions of the Main Resistive Element cannot be controlled exactly. It will be appreciated by the alert reader that it is desirable to have as small resistance of the high-current shunt, as possible, to minimize the so-called resistive or Joule heat losses. Therefore, the width of the Main Resistive Element is made to be very narrow, as to reduce the overall resistance.
  • the TCR of the whole shunt depends on the resistance of the Main Resistive Element and on the resistance of the (copper) portions of the terminals between the welding lines to the Main Resistive Element and the Sensing Points.
  • the invention draws upon an insight that if the distance between the Sensing Points is precisely defined and is repeatable (for example, due to the punching tool used to create the holes for the Sensing Points), then accurate calibration and determination of the Thermal Compensation function of the shunt can be done by means of a single measurement at room temperature.
  • the shunt can be used to achieve veiy accurate current measurements at any of a range of temperatures, and yet (perhaps counter intuitively) the calibration itself only needs to be carried out at a single temperature.
  • Figure 1 shows a typical shunt suitable for measuring large values of current.
  • Figure 2 shows a typical temperature coefficient of resistence for manganin.
  • Figure 3 shows a typical dependency of resistivity upon temperature for copper.
  • Figure 4 shows a simplified make-up of a typical shunt.
  • Figure 5 depicts thermal characteristics of several shunts that are nearly identical.
  • Figure 6 shows a plurality of sloped lines each representing the resistance dependence of a particular shunt that differs from other shunts.
  • Figure 7 shows how other shunts (among many shunts) compare with a nominal-center shunt in terms of deviations due to temperature change.
  • Figure 8 shows manufacturing variations from one shunt to the next in thermal behavior of each of the shunts.
  • Figure 9 shows which shows in block diagram form a shunt resistance model.
  • Figure 10 shows a number of curves each modeling resistance as a function of temperature, each curve tied to a particular geometry of a particular shunt.
  • Figure 11 shows in block diagram form the sequence of steps for arriving at a resistance model for a particular shunt.
  • Figure 12 shows selection of one curve based upon one resistance measurement of a shunt at one temperature.
  • a single calibration measurement takes place for a particular shunt (typically a shunt that has just been manufactured).
  • a single measurement permits later use of the shunt to cariy out accurate current measurements across a range of temperatures differing substantially from that single temperature at which the calibration measurement was carried out.
  • Figure 5 depicts thermal characteristics of several shunts that are nearly identical but with the variation of the resistance due to variations of the width for the Main Resistive Element.
  • Each angled line on the graph shows dependence of resistance upon temperature for each of a number of particular shunts, each different from the next due to non-identical values for the width of the Main Resistive Element.
  • the insight relied upon for the present invention will now be understood by the alert reader.
  • the alert reader will recognize that the individual curves for individual shunts among many, can be readily rotated, based on the initial room-temperature resistance for each particular shunt, with the result that only a single pre-computed Compensation Table or Formula has to be discovered (specifically, and only for the shunt with the nominal room-temperature resistance).
  • a key parameter in shunt-based current measurement systems is the resistance of the shunt as a function of the shunt temperature.
  • the temperature of a particular shunt when in use for actual current measurements is likely to change from time to time; for example the temperature of the shunt can increase for the veiy reason that a high current has recently flowed through the shunt.
  • the temperature of the shunt can increase due to various physical effects.
  • the shunt is of course necessarily thermally coupled with its environment, and thus this also affects the temperature of the shunt. Said differently, if the temperature nearby to the shunt goes higher or lower, this may tend to raise or lower the temperature of the shunt accordingly.
  • the insight is that for each particular shunt that has been manufactured, a single-point calibration method can be performed at a single temperature point.
  • the method described here makes it possible in a shunt-based current measurement system to account for variations in the shunt dimensional properties due to the manufacturing process (for example the above- mentioned variations in welding). In particular, it accounts for variations in the geometric parameters of the shunt. For a copper-manganin shunt it will account for variations in the ratio of the two components. This method is enhances the accuracy of the shunt-based current measurement system while maintaining a fast calibration time.
  • Figure 9 shows in block diagram form a shunt resistance model.
  • a model for shunt resistance as a function of temperature is constructed from physics-based and knowledge-based approaches. The outcome is a model for resistance that takes two inputs - the temperature of the shunt T, and a value alpha that pulls together the geometical (dimensional) parameters of the particular shunt.
  • the knowledge-based approach draws upon data collected from a large number of shunts, to validate the physics-based model.
  • Figure 10 shows a number of curves (functions) predicting resistance of a particular shunt over a range of temperatures, and each curve takes into account variations in geometry of particular shunts. For each particular shunt that has been manufactured, we carry out just one resistance measurement at some predetermined temperature, and this permits selecting one or another of the curves depicted in Figure 10 for that shunt.
  • Figure 11 shows in block diagram form the sequence of steps for arriving at a resistance model for a particular shunt.
  • the first block assumes that we have arrived at a functional model for resistivity as a function of temperature, the model yielding a shunt resistance based upon a temperature at which the calibration took place, and the value alpha that is based upon the known geometry of the shunt, here assumed to be a precise knowledge of the distance between Sensing Points.
  • Figure 12 shows selection of one curve based upon one resistance measurement of a shunt at one temperature.
  • one resistance measurement is carried out, and this permits selecting one curve from the model. That curve is relied upon subsequently to permit accurate current measurements in actual operation. It will thus be helpful to make a distinction between calibration and operation.
  • a particular shunt, perhaps newly manufactured, will get calibrated. After that, it is placed into operation.
  • the operational phase involves many current measurements, each of which involves passing a current through the shunt and measuring voltage at sensing points, and making note of the temperature of the shunt at the time of the voltage measurement.
  • each shunt comprising a first region made of a first material having a first specific resistivity, each shunt having to one side of the first region a second region made of a second material having a second specific resistivity, the second region mechanically connected to the first region, each shunt having to an opposite side of the first region a third region made of the second material, the third region mechanically connected to the first region, the second specific resistivity being lower than the first specific resistivity, the second material varying in resistivity as a function of temperature more than the first material, the second region and third region each having a respective first and second sensing point, for each shunt the first and second sensing points defining a known respective distance therebetween.
  • One part of the calibration process is that for for each shunt among the plurality of other shunts in addition to the first shunt, measurements of resistance between the sensing points are carried out at each of a plurality of temperatures, and a note is made of the distance between the sensing points for the each shunt.
  • Another part of the calibration process is that a model is devised for shunt resistance as a function of temperature and as a function of the distance between the sensing points.
  • Another part of the calibration process is that for some particular shunt, typically a shunt that has just been manufactured, a single calibration defined by a measurement of resistance between the sensing points at a single predetermined temperature is carried out, and a note is made of the distance between the sensing points for the first shunt.
  • the first shunt is then placed into operational service.
  • a first operation is carried out with the first shunt, measuring a first operational current at a first operational temperature that is different from the single predetermined temperature, the first operational current arrived at by measuring a first voltage between the sensing points and dividing it by a first resistance derived from the model based upon the first operational temperature. It will be borne in mind that the derivation of the first resistance from the model does not depend upon geometric measurements at the first shunt other than the distance between the sensing points for the first shunt.
  • the shunt in operation, arrives at some second operational temperature that is different from the single predetermined temperature and that is different from the first operational temperature.
  • a second operation is carried out with the first shunt, measuring a second operational current.
  • the second operational current is arrived at by measuring a second voltage between the sensing points and dividing it by a second resistance derived from the model based upon the second temperature. It is again borne in mind that the derivation of the second resistance from the model does not depend upon geometric measurements at the first shunt other than the distance between the sensing points for the first shunt.
  • the shunt in operation, arrives at some third operational temperature that is different from the single predetermined temperature and that is different from the first operational temperature and that is different from the second operational temperature.
  • a third operation is carried out with the first shunt, measuring a third operational current.
  • the third operational current is arrived at by measuring a third voltage between the sensing points and dividing it by a third resistance derived from the model based upon the third temperature. It is yet again borne in mind that the derivation of the third resistance from the model does not depend upon geometric measurements at the first shunt other than the distance between the sensing points for the first shunt.
  • the first material is manganin and the second material is copper.
  • the mechanical connection between the first and second region is a welded connection
  • the mechanical connection between the first and third regions is a welded connection
  • the model that is devised for this inventive approach to predicting thermal resistive behavior of shunts.
  • the benefits of the invention do not require the use of any particular model other than that the model require and depend upon the limited inputs described, such as a resistance measurement of a newly manufactured shunt at a single temperature as distinguished from some other model that would require measurements at each of several distinct temperatures.
  • the model could be as simple as the selection of one or another of the sloped lines depicted in Figure 5, depending on the resistance that was measured in the newly manufactured shunt.
  • the model could, as discussed above, be a model based upon physics, taking into account the dimensions and geometry of the various parts of the shunt, the known electrical properties of the material from which each of the parts of the shut is made, and the physical locations of the sensing points.
  • the model could, as discussed above, be a model based upon a methodical empirical measurement of resistances in various shunts at various temperatures, with an assumption that the manufacturing process that yielded the shunts is fairly consistent in the resulting geometry of the parts of the shunt, and is fairly consistent in the places where the sensing points are connected to the shunt. Desirably the model can be a blend of these two approaches.
  • the alert reader will have no difficulty selecting a model among these possible approaches, or devising a model that is a blend of two or more of these possible approaches.
  • the steps of the method are detailed above, and in the claims, it is not intended that the method be limited to any one exact detailed model, but instead it is intended merely that the model be a suitable model which, for a particular newly manufactured shunt, takes as its input only a resistance measurement at a single temperature, and does not require, for that particular newly manufactured shunt, a plurality of resistance measurements at a plurality of respective temperatures.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)

Abstract

L'invention s'appuie sur une idée selon laquelle, si la distance entre les points de détection d'un shunt est définie avec précision et est reproductible (par exemple, en raison de l'outil de poinçonnage utilisé pour créer les trous pour les points de détection), l'étalonnage et la détermination précis de la fonction de compensation thermique du shunt peuvent être exécutés au moyen d'une mesure unique à température ambiante. En d'autres termes, une fois que l'étalonnage selon l'invention a été exécuté, le shunt peut être utilisé pour obtenir des mesures de courant très précises dans n'importe quelle plage de températures ; pourtant (peut-être de manière contre-intuitive), l'étalonnage même doit uniquement être exécuté à une température unique.
PCT/IB2021/051168 2020-02-12 2021-02-12 Procédé de prédiction de comportement de résistance thermique de shunts Ceased WO2021161237A1 (fr)

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US202062975680P 2020-02-12 2020-02-12
US62/975,680 2020-02-12

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114755490A (zh) * 2022-03-24 2022-07-15 浙江瑞银电子有限公司 一种大电流分流器
CN116026495A (zh) * 2022-12-30 2023-04-28 北京康斯特仪表科技股份有限公司 一种温度仪表的多任务检测方法及检测主机
CN117590115A (zh) * 2023-11-16 2024-02-23 宁波博银谐波科技有限公司 一种电阻器的测试方法及测试装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011028870A1 (fr) * 2009-09-04 2011-03-10 Vishay Dale Electronics, Inc. Résistance avec compensation de coefficient thermique de résistance électrique (tcr)
KR101448936B1 (ko) * 2014-03-27 2014-10-13 태성전장주식회사 전류센서용 션트 저항 모듈과 이를 이용한 차량용 배터리
US20170012331A1 (en) * 2014-10-23 2017-01-12 Quantum Force Engineering Limited Battery Assembly
US9632163B2 (en) * 2011-06-29 2017-04-25 Robert Bosch Gmbh Method and system for calibrating a shunt resistor
US20170212148A1 (en) * 2014-08-01 2017-07-27 Isabellenhuette Heusler Gmbh & Co. Kg Resistor, in particular low-resistance current measuring resistor

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011028870A1 (fr) * 2009-09-04 2011-03-10 Vishay Dale Electronics, Inc. Résistance avec compensation de coefficient thermique de résistance électrique (tcr)
US9632163B2 (en) * 2011-06-29 2017-04-25 Robert Bosch Gmbh Method and system for calibrating a shunt resistor
KR101448936B1 (ko) * 2014-03-27 2014-10-13 태성전장주식회사 전류센서용 션트 저항 모듈과 이를 이용한 차량용 배터리
US20170212148A1 (en) * 2014-08-01 2017-07-27 Isabellenhuette Heusler Gmbh & Co. Kg Resistor, in particular low-resistance current measuring resistor
US20170012331A1 (en) * 2014-10-23 2017-01-12 Quantum Force Engineering Limited Battery Assembly

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114755490A (zh) * 2022-03-24 2022-07-15 浙江瑞银电子有限公司 一种大电流分流器
CN116026495A (zh) * 2022-12-30 2023-04-28 北京康斯特仪表科技股份有限公司 一种温度仪表的多任务检测方法及检测主机
CN117590115A (zh) * 2023-11-16 2024-02-23 宁波博银谐波科技有限公司 一种电阻器的测试方法及测试装置

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