WO2017158373A1 - Mesure de température - Google Patents

Mesure de température Download PDF

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Publication number
WO2017158373A1
WO2017158373A1 PCT/GB2017/050745 GB2017050745W WO2017158373A1 WO 2017158373 A1 WO2017158373 A1 WO 2017158373A1 GB 2017050745 W GB2017050745 W GB 2017050745W WO 2017158373 A1 WO2017158373 A1 WO 2017158373A1
Authority
WO
WIPO (PCT)
Prior art keywords
temperature
fixed value
multiplexer
voltages
value resistors
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2017/050745
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English (en)
Inventor
Peter John Miller
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Johnson Matthey PLC
Original Assignee
Johnson Matthey PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Johnson Matthey PLC filed Critical Johnson Matthey PLC
Publication of WO2017158373A1 publication Critical patent/WO2017158373A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
    • G01K7/16—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using resistive elements
    • 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
    • G01K1/02—Means for indicating or recording specially adapted for thermometers
    • G01K1/026—Means for indicating or recording specially adapted for thermometers arrangements for monitoring a plurality of temperatures, e.g. by multiplexing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K15/00—Testing or calibrating of thermometers
    • G01K15/007—Testing

Definitions

  • the present invention relates to temperature measurement systems and methods for measuring a plurality of temperatures.
  • the present invention relates to temperature measurement systems for use in battery management systems and methods for measuring a plurality of temperatures in battery packs.
  • Known methods of measuring temperatures include temperature dependent resistors, such as thermistors or resistance temperature detectors (RTD), and semi-conductor junctions, such as diodes and transistors.
  • Thermistors can have a negative temperature coefficient (NTC) or a positive temperature coefficient (PTC).
  • NTC negative temperature coefficient
  • PTC positive temperature coefficient
  • a typical system would involve a current source that is passed through a current multiplexer to deliver a source current to multiple temperature detectors such as thermistors or RTDs.
  • the output voltages of the temperature detectors are passed through a voltage multiplexer to create a single signal that is passed to an analogue to digital converter, which creates a digital signal to pass to a processor.
  • the multiplexers have a fixed number of channels available and a single temperature detector will typically be connected to each channel. While such systems work well there is no built in self-test capability so the system cannot confirm that the correct temperature, or indeed any temperature, is being measured.
  • Preferred embodiments of the present invention seek to overcome one or more of the above disadvantages of the prior art. In particular, preferred embodiments of the present invention seek to provide an improved system and method for measuring temperature. Summary of Invention
  • a temperature measurement system comprising: a current source; a first multiplexer having an input channel, connected to the current source, and a plurality of output channels; a second multiplexer having an output channel, connected to a processor, and a plurality of input channels; and a plurality of temperature sensors, each sensor being connected to an output channel of the first multiplexer so that the sensor can receive current from the current source via the first multiplexer and to an input channel of the second multiplexer so that a voltage across the sensor can be monitored by the processor via the second multiplexer; wherein the system further comprises two fixed value resistors, each fixed value resistor being connected to an output channel of the first multiplexer so that the fixed value resistor can receive current from the current source via the first multiplexer and to an input channel of the second multiplexer so that a voltage across the fixed value resistor can be measured by the processor via the second multiplexer.
  • the system may comprise an analogue to digital converter to convert measured voltages into digital signals for
  • the temperature measurement system of the present invention includes two fixed value resistors connected to the multiplexers in the same way as the temperature sensors. Because the resistance of, and hence the voltage dropped across, the fixed value resistors does not change with temperature, the processor can check that the temperature measurement system is operating correctly by confirming that the expected values are being read for the two fixed value resistors. Examples of faults that can be detected include a multiplexer address line being stuck at a value (0 or 1), faults in the current source, faults in any analogue to digital converter included in the circuit (for example between the second multiplexer and the processor) and faults within the multiplexers.
  • the temperature sensors may for example be thermistors, resistance temperature detectors
  • the system may comprise an analogue to digital converter to convert measured voltages into digital signals for processing by the processor.
  • One analogue to digital converter may be provided per input channel of the second multiplexer but preferably a single analogue to digital converter is provided between the output of the second multiplexer and the processor.
  • the processor may, for example, be a microprocessor or an application specific integrated circuit (ASIC).
  • the two fixed value resistors are connected to output channels that are the complement of each other on the first multiplexer and input channels that are the complement of each other on the second multiplexer.
  • the multiplexer has four address lines
  • one of the temperature sensors may be connected to channel 1010 on each multiplexer and the other temperature sensor to 0101 on each multiplexer.
  • other complimentary channel pairs such as 1000 and 0001 , could be used and different complementary pairs could be used on each multiplexer.
  • the two fixed value resistors have different values to each other.
  • the values are selected to give voltages either side (i.e. one above and one below) of the range of voltages generated by the temperature sensors over the temperature range of interest.
  • one of the fixed value resistors may have a value such that the voltage across the fixed value resistor is not less than 75%, preferably 90%, and more preferably 99%, of the minimum voltage generated by the temperature sensors over the temperature range of interest.
  • the voltage across that fixed value resistor is preferably also not more than 105%, preferably 100%, and more preferably
  • the other of the fixed value resistors may have a value such that the voltage across the fixed value resistor is not more than 125%, preferably 1 10%, and more preferably 101 %, of the maximum voltage generated by the temperature sensors over the temperature range of interest.
  • the voltage across that fixed value resistor is preferably also not less than 95%, preferably 100%, and more preferably 100.05%, of the maximum voltage generated by the temperature sensors over the temperature range of interest. In that way the expected measurement range is bracketed by the two fixed value resistors.
  • the processor is configured to use measured voltages across the two fixed value resistors in calculating the temperature measured by a temperature sensor.
  • the processor may be configured to use the measured voltages across the two fixed value resistors to account for imperfections in the current source, multiplexers or any analogue to digital converter in the system.
  • the processor is configured to interpolate between the measured voltages across the two fixed value resistors to calculate the resistance of the temperature sensor based on the known resistance of the fixed value resistors.
  • the interpolation may be carried out directly in a single step or indirectly, for example by using the measured voltages across the two fixed value resistors to calculate coefficients in a linear relationship between voltage and resistance and subsequently using the calculated coefficients to calculate the resistance of the temperature sensor. It will be appreciated that such a calculation may be applied when, for example, a thermistor or RTD is used as the temperature sensor.
  • the processor may be configured to measure voltages across a temperature sensor and the two fixed resistors at different currents and to calculate the temperature based on the currents and the measured voltages.
  • the voltages may be measured at two different currents, at three different currents or even at more different currents.
  • the processor is configured to measure voltages across a temperature sensor and the two fixed resistors at two different currents and to calculate the temperature based on the ratio of the two currents and the difference in the measured voltages across the temperature sensor at the two different currents.
  • the processor is configured to determine the ratio of the currents based on the measured voltages across the two fixed value resistors at the two different currents and to use the ratio thus calculated in the calculation of the temperature.
  • the processor is configured to measure voltages across a temperature sensor and the two fixed resistors at three different currents and to calculate the temperature based on ratios of the currents and the difference in the measured voltages across the temperature sensor at the different currents. Such calculations may be applied when, for example, a transistor or a diode is used as the temperature sensor.
  • the temperature sensor may be a semiconductor temperature sensor and the temperature may be calculated based on the base-emitter voltage of the semiconductor temperature sensor at the different currents.
  • Using two or three different currents may be advantageous in that the measured voltages across the fixed value resistors are used to account for any inaccuracies in the current supplied to the temperature sensors, for example due to inaccuracy in the current source, resistance in the circuit to the sensor, or current leakages in the multiplexers.
  • the system of the invention may be particularly advantageous for use in a battery management system.
  • a battery pack typically contains a number of cells arranged in series and the cell temperature of each cell may be monitored for safety reasons. That monitoring is typically carried out by a battery management system that forms part of the battery pack.
  • a particularly advantageous arrangement includes 14 lithium ion cells arranged in series, giving a cell pack voltage of around 50V. If the temperature of each cell is measured by a temperature sensor in a system of the invention comprising multiplexers with 4 address lines, each multiplexer has 16 channels, which match with the 14 temperature sensors and 2 fixed value resistors. In that way the system makes efficient use of the multiplexers to provide robust and accurate temperature measurement of the cell temperatures.
  • a battery management system comprising a temperature measurement system according to the first aspect of the invention.
  • a method of measuring a plurality of temperatures comprising supplying current from a current source, via a first multiplexer, to a plurality of temperature sensors; and measuring, via a second multiplexer, a voltage across each of the plurality of temperature sensors; wherein the method further comprises supplying current from the current source, via the first multiplexer, to two fixed value resistors; measuring, via the second multiplexer, a voltage dropped across each of the fixed value resistors; and determining the temperature at each of the temperature sensors based on the voltage measured across the temperature sensor and the voltages measured across the fixed value resistors.
  • the method comprises confirming that the voltages measured across the fixed value resistors fall within an expected range. In that way, the correct functioning of the measurement system may be confirmed. Preferably that confirmation is carried out prior to determining the temperature at each of the temperature sensors.
  • the method may include confirming that the voltages measured across the fixed value resistors fall within 10%, preferably 1 % of their expected values. If they do, the method may include using those voltages in the calculation of the temperatures at each of the temperature sensors. If they do not, the method may include entering an error state.
  • the temperature at a temperature sensor is determined by relating, for example by interpolation, the voltage across the sensor to the voltages across the two fixed value resistors and thus determining the resistance of the sensor based on the known resistances of the two fixed value resistors.
  • Such a method may be advantageous in that the calculation does not used the value of the current supplied by the current source and thus accounts for any errors due to differences between the theoretical and actual values of the current delivered from the current source.
  • the temperature at a temperature sensor is determined by supplying multiple, for example two or three, different currents from the current source and measuring the voltages across the sensor and the fixed value resistors at each of the different currents and determining the temperature based on, for example the difference in, the voltages across the sensor measured at the different currents and, for example ratios of, the different currents.
  • ratios of the different currents are determined based on the voltages measured across the fixed value resistors at the different currents. That may provide the advantage that the calculation does not use the theoretical value of the supplied current and thus accounts for any errors between the theoretical current and the actual current supplied to the sensors and the fixed value resistors.
  • Figure 1 is schematic diagram of a temperature measurement system according to an embodiment of the invention.
  • a temperature measurement system 1 comprises a current source 2.
  • the current source 2 is connected to the input channel 5 of a first multiplexer M ⁇ .
  • the first multiplexer Iv ⁇ has four output channels 6a, 6b, 6c and 6d with addresses 00, 01 , 10 and 1 1 respectively.
  • Channels 6a and 6d are connected to temperature sensors T 2 and T 7 while channels 6b and 6c are connected to fixed value resistors R 2 and F ⁇ .
  • the temperature sensors and T 2 are thermistors.
  • the temperature sensors and T 2 and the fixed value resistors F ⁇ and R 2 are also connected to the input channels 7a, 7b, 7c and 7d of a second multiplexer M 2 .
  • the multiplexer M 2 outputs the signals from the temperature sensors and T 2 and the fixed value resistors R ⁇ and R 2 on output channel 8 to a processor 3 via an analogue to digital converter ADC.
  • the processor 3 can control the address lines 4 of the multiplexers Iv ⁇ and M 2 .
  • the current source In use the current source generates a current which is supplied to the temperature sensors and T 2 and the fixed value resistors R ⁇ and R 2 via the multiplexer M ⁇ .
  • the processor 3 measures the voltages dropped across each of the temperature sensors and T 2 and the fixed value resistors RT and R 2 via the multiplexer M 2 and the analogue to digital converter ADC.
  • the temperatures at the temperature sensors and T 2 are measured by measuring the resistance of the thermistors. That can be done by comparing the voltages measured across the fixed value resistors with the voltages measured across the thermistors.
  • R ⁇ ⁇ / ⁇ .
  • errors in the current source or elsewhere in the system may alter the value of the current delivered to the temperature sensors and T 2 and the fixed value resistors R ⁇ and R 2 from the theoretical value I supplied by the source or may result in offset errors in the measured voltages.
  • the temperature sensors could also be another type of temperature sensor, such as RTDs or diodes or transistors.
  • voltage measurements may be taken at multiple, for example two or three, different currents in order to calculate the temperature.
  • voltage measurements may be taken at two different currents I , and l 2 .
  • the ratio l 2 / of the actual current supplied to the resistors can be determined from the measured voltages across the resistors R ⁇ and R 2 without needing to use the theoretical current values supplied from the current source.
  • the embodiment of the invention thus uses the voltages measured across the fixed value resistors RT and R 2 to correct for correctable errors in the measurement circuit and thus to improve the accuracy of the temperature measurement.
  • the system 1 also uses the voltages to check that the system is working as expected. For example, if the second multiplexer M 2 has failed such that the first bit is stuck at 0, then the voltages will always be measured on channels 7a or 7b, even if channels 7c or 7d were intended.
  • the system 1 detects that the voltage obtained on, allegedly, channel 7c does not match within a predetermined tolerance (say 1 %) the value that would be expected for resistor R ⁇ for the current supplied by the current source 2. Since the deviation exceeds the allowable tolerance the system 1 does not use the voltage to calculate temperatures from the temperature sensors and T 2 , but instead enters an error mode and issues an alert.
  • the tolerance is chosen so that anticipated normal variations in the performance of the current source or multiplexer current leakages (i.e. correctable errors) do not trigger the error mode and are instead compensated in the calculation method, while fatal errors, such as failure of a multiplexer or M 2 to correctly select the instructed channel will trigger the error mode. In that way a robust and accurate measurement system is provided.
  • the multiplexers could include more channels and thus more temperature sensors could be connected to the system along with the two fixed value resistors. In some embodiments a mixture of different types of temperature sensors could be used.
  • the processor 3 could be the battery management system of a battery pack, for example for an electric vehicle, and the temperature sensors ⁇ and T 2 (and others if present) could be mounted on individual cells within the battery pack.
  • the multiplexers have four address lines, giving 16 channels, 14 of which are connected to temperature sensors attached to lithium ion cells in series in a battery pack of around 50V and two of which are connected to fixed value resistors.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

L'invention concerne un système de mesure de température. Le système comprend: une source de courant; un premier multiplexeur ayant un canal d'entrée raccordé à la source de courant, et une pluralité de canaux de sortie; un second multiplexeur ayant un canal de sortie raccordé à un processeur, et une pluralité de canaux d'entrée; et une pluralité de capteurs de température. Chaque capteur est raccordé d'une part à un canal de sortie du premier multiplexeur de sorte que le capteur puisse recevoir du courant d'une source de courant par le biais du premier multiplexeur, et d'autre part à un canal d'entrée du second multiplexeur de sorte qu'une tension aux bornes du capteur puisse être surveillée par le processeur par le biais du second multiplexeur. Le système comprend en outre deux résistances de valeur fixe. Chaque résistance de valeur fixe est raccordée d'une part à un canal de sortie du premier multiplexeur de sorte que la résistance de valeur fixe puisse recevoir du courant de la source de courant par le biais du premier multiplexeur, et d'autre part à un canal d'entrée du second multiplexeur de sorte qu'une tension aux bornes de la résistance de valeur fixe puisse être mesurée par le processeur par le biais du second multiplexeur.
PCT/GB2017/050745 2016-03-18 2017-03-17 Mesure de température Ceased WO2017158373A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
GB1604660.9 2016-03-18
GB1700144.7A GB2547978B (en) 2016-03-18 2016-03-18 Temperature measurement
GB1700143.9A GB2548452B (en) 2016-03-18 2016-03-18 Temperature Measurement
GB1604660.9A GB2541482B (en) 2016-03-18 2016-03-18 Temperature measurement
GB1700143.9 2017-01-05
GB1700144.7 2017-01-05

Publications (1)

Publication Number Publication Date
WO2017158373A1 true WO2017158373A1 (fr) 2017-09-21

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PCT/GB2017/050745 Ceased WO2017158373A1 (fr) 2016-03-18 2017-03-17 Mesure de température

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GB (3) GB2548452B (fr)
WO (1) WO2017158373A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111552275A (zh) * 2020-05-20 2020-08-18 深圳开立生物医疗科技股份有限公司 一种温控校准装置、温控设备及其方法
CN113514699A (zh) * 2020-04-09 2021-10-19 台达电子工业股份有限公司 热控系统、热控方法与温度校正装置

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Publication number Priority date Publication date Assignee Title
DE102016224918A1 (de) * 2016-12-14 2018-06-14 Bayerische Motoren Werke Aktiengesellschaft Verfahren zum Überprüfen eines Temperatursensors einer Hochvolt-Batterie, sowie Antriebsstrang mit einer solchen Hochvolt-Batterie
FR3096758B1 (fr) 2019-05-29 2021-06-25 Valeo Vision Procédé de fonctionnement d'un dispositif pour véhicule automobile et dispositif pour véhicule automobile
FR3105411A1 (fr) 2019-12-19 2021-06-25 Psa Automobiles Sa Dispositif de mesure à deux sondes de température pour un véhicule
EP4060299B1 (fr) 2021-03-18 2025-04-23 B/E Aerospace, Inc. Dispositif multiplexeur
DE102021208562A1 (de) * 2021-08-06 2023-02-09 Carl Zeiss Smt Gmbh Temperaturmessvorrichtung, lithographieanlage und verfahren zum messen einer temperatur
US20230366754A1 (en) * 2022-05-11 2023-11-16 Cirrus Logic International Semiconductor Ltd. Single-point temperature calibration of resistance-based temperature measurements
CN115752792B (zh) * 2022-11-14 2024-08-23 常州大学 一种多路温度测量电路及测量方法

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Publication number Priority date Publication date Assignee Title
EP0120102A1 (fr) * 1983-03-23 1984-10-03 Firma Carl Zeiss Dispositif de mesure de température
DE3313559A1 (de) * 1983-04-14 1984-10-25 Siemens AG, 1000 Berlin und 8000 München Anordnung zum messen und/oder ueberwachen der temperaturen in maschinen oder geraeten
EP2199766A2 (fr) * 2008-12-18 2010-06-23 BSH Bosch und Siemens Hausgeräte GmbH Vaisselle de cuisson dotée d'un circuit de mesure de la température

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US8182139B2 (en) * 2008-05-30 2012-05-22 Apple Inc. Calibration of temperature sensing circuitry in an electronic device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0120102A1 (fr) * 1983-03-23 1984-10-03 Firma Carl Zeiss Dispositif de mesure de température
DE3313559A1 (de) * 1983-04-14 1984-10-25 Siemens AG, 1000 Berlin und 8000 München Anordnung zum messen und/oder ueberwachen der temperaturen in maschinen oder geraeten
EP2199766A2 (fr) * 2008-12-18 2010-06-23 BSH Bosch und Siemens Hausgeräte GmbH Vaisselle de cuisson dotée d'un circuit de mesure de la température

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113514699A (zh) * 2020-04-09 2021-10-19 台达电子工业股份有限公司 热控系统、热控方法与温度校正装置
CN111552275A (zh) * 2020-05-20 2020-08-18 深圳开立生物医疗科技股份有限公司 一种温控校准装置、温控设备及其方法

Also Published As

Publication number Publication date
GB2548452B (en) 2018-03-07
GB2541482A (en) 2017-02-22
GB2547978A (en) 2017-09-06
GB201604660D0 (en) 2016-05-04
GB2541482B (en) 2018-01-31
GB2547978B (en) 2018-02-07
GB201700144D0 (en) 2017-02-22
GB201700143D0 (en) 2017-02-22
GB2548452A (en) 2017-09-20

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