KR101774664B1 - Apparatus and method for detecting temperature - Google Patents

Apparatus and method for detecting temperature Download PDF

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KR101774664B1
KR101774664B1 KR1020150164317A KR20150164317A KR101774664B1 KR 101774664 B1 KR101774664 B1 KR 101774664B1 KR 1020150164317 A KR1020150164317 A KR 1020150164317A KR 20150164317 A KR20150164317 A KR 20150164317A KR 101774664 B1 KR101774664 B1 KR 101774664B1
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South Korea
Prior art keywords
temperature
reference frequency
processor
capacitor
output voltage
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KR1020150164317A
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Korean (ko)
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KR20170059841A (en
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이재원
나정환
정지혜
곽상훈
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현대자동차주식회사
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    • 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
    • G01K7/34—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements using capacitative 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
    • G01K1/20—Compensating for effects of temperature changes other than those to be measured, e.g. changes in ambient temperature
    • 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
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/145—Indicating the presence of current or voltage
    • G01R19/155—Indicating the presence of voltage

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

The present invention relates to an apparatus and method for measuring a temperature, comprising a frequency generator for generating a voltage of a specific waveform according to a reference frequency, a capacitor connected to an output terminal of the frequency generator for receiving the voltage of the specific waveform, And a processor that adjusts the reference frequency to an output voltage according to the temperature and calculates a temperature using the reference frequency and an output voltage according to the temperature.

Description

[0001] APPARATUS AND METHOD FOR DETECTING TEMPERATURE [0002]

The present invention relates to a temperature measuring apparatus and method, and more particularly, to a temperature measuring apparatus and method that can precisely measure a temperature by utilizing an impedance characteristic of a capacitor varying with frequency.

Generally, a temperature sensor of NTC (Negative Temperature Coefficient) type or PTC (Positive Temperature Coefficient) type is used for the temperature measurement. The resistance value of the sensor increases or decreases according to the temperature change.

Such a temperature sensor has a simple circuit structure and is advantageous in that it is easy to use. However, when the temperature range of the engine room is changed from -40 to 150 degrees, as in the case of a vehicle engine room, the output value of the sensor is 0 or several megaohms (M OMEGA).

Generally, for temperature measurement, one resistor is connected in series to measure the divided value. It is difficult to set an appropriate resistance value when the resistance value changes from several ohms to several mega ohms. When the value is set to a low value, the sensing accuracy is lower than several hundred k ?, and when the temperature sensor has a resistance value of several tens of? This results in high or low temperature regions giving up sensing.

In the case of detecting a disconnection or a short circuit, restriction of disconnection or short circuit detection is inevitable by selecting a resistance value. That is, a section with low sensing accuracy necessarily occurs, and it is impossible to detect a short circuit or a short circuit fault.

KR 101091667 B1

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the related art as described above, and it is an object of the present invention to provide a temperature measuring apparatus and method which can precisely measure a temperature by utilizing an impedance characteristic of a capacitor varying with frequency.

According to an aspect of the present invention, there is provided a temperature measuring apparatus comprising: a frequency generator for generating a voltage of a specific waveform according to a reference frequency; a frequency generator connected to an output terminal of the frequency generator, A temperature sensor for receiving a voltage of the specific waveform and outputting an output voltage according to the temperature, and a control unit for adjusting the reference frequency to an output voltage according to the temperature, And a processor for calculating the output of the processor.

Wherein the temperature sensor is constituted by one or more resistive sensors whose resistance values vary with temperature.

The resistive sensor may be a negative temperature coefficient (NTC) type or a positive temperature coefficient (PTC) type thermistor.

And the processor adjusts the reference frequency to vary the impedance of the capacitor.

The temperature measuring apparatus further includes a switch provided between the capacitor and the temperature sensor for switching the temperature measurement channel under the control of the processor.

The temperature measuring apparatus further includes an amplifier connected to an output terminal of the switch and transmitting measurement data measured through the temperature measurement channel to the processor.

The processor is characterized by calibrating the impedance of the capacitor at regular intervals.

And the processor reduces the reference frequency when the detected output voltage exceeds a target value.

And the processor increases the reference frequency when the detected output voltage is less than a target value.

Meanwhile, the temperature measuring method according to an embodiment of the present invention includes switching a temperature measurement channel by selecting one of the one or more resistive sensors, switching the temperature measurement channel, and determining whether an existing reference frequency exists Generating a voltage of a specific waveform of a reference frequency according to a result of checking whether the existing reference frequency exists, and applying the generated voltage to a capacitor and a selected resistive sensor; detecting an output voltage according to a temperature of the resistive sensor; And adjusting the reference frequency to an output voltage according to the temperature, and calculating a temperature using the frequency of the voltage of the specific waveform and the output voltage.

The temperature measuring method may further include generating the voltage of the specific waveform according to a preset reference frequency to the selected resistive sensor and applying the generated voltage to the capacitor and the selected resistive sensor when the existing reference frequency does not exist .

And the reference frequency is decreased when the output voltage according to the temperature exceeds the target value in the temperature calculation step.

And the reference frequency is increased when the output voltage according to the temperature is less than a target value in the temperature calculating step.

The present invention can improve the temperature measurement accuracy by measuring the temperature by utilizing the impedance characteristic of the capacitor which changes according to the frequency.

Further, according to the present invention, since the detection performance of disconnection or short circuit is improved, the possibility of false alarm detection is lowered and the reliability of the product can be improved.

1 is a block diagram of a temperature measuring apparatus according to an embodiment of the present invention;
2 is a flow chart illustrating a temperature measurement method in accordance with an embodiment of the present invention.

The terms "comprises", "comprising", "having", and the like are used herein to mean that a component can be implanted unless otherwise specifically stated, Quot; element ".

Also, the terms " part, "" module, " and" module ", as used herein, refer to a unit that processes at least one function or operation and may be implemented as hardware or software or a combination of hardware and software . It is also to be understood that the articles "a", "an", "an" and "the" Can be used.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 shows a block diagram of a temperature measuring apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the temperature measuring device includes a temperature sensor 100 and a measuring device 200.

The temperature sensor 100 serves to sense the ambient temperature. The temperature sensor 100 is composed of one resistive sensor 110 or 120 or two or more resistive sensors 110 and 120 whose resistance value changes according to the temperature. The resistive sensors 110 and 120 may be implemented with a negative temperature coefficient (NTC) type or a positive temperature coefficient (PTC) type thermistor. In the present embodiment, the temperature sensor 100 is configured by two resistive sensors 110 and 120 as an example to facilitate the understanding of the description. However, the present invention is not limited to this, and a temperature sensor 100 composed of three or more resistive sensors (100).

The measuring device 200 measures the ambient temperature through the temperature sensor 100. The meter 200 includes a frequency generator 210, a switch 220, an amplifier 230, a processor 240, and the like.

The input terminal of the frequency generator 210 is connected to the processor 240 and receives a reference frequency output from the processor 240. Then, the frequency generator 210 generates a voltage (for example, 5 V) of a specific waveform according to the input reference frequency. The frequency generator 210 may be implemented as a frequency to voltage converter.

Here, the reference frequency may be a frequency set for each of the resistive sensors 110 and 120 or a frequency set by the processor 240. And, the specific waveform may be a sine wave.

One end of the capacitor C1 is connected to the output terminal of the frequency generator 210. [ The capacitor C1 has an impedance Zc that varies depending on the frequency of a specific waveform output from the frequency generator 210. [ The impedance Zc of the capacitor C1 can be obtained by the following equation (1).

Figure 112015114290872-pat00001

Here, f is the frequency of the waveform output from the frequency generator 210, C is the capacitance of the capacitor C1, and? Is the circumferential rate (= 3.14).

The output terminal of the switch 220 is connected to the other end of the capacitor C1 and the two resistive sensors 110 and 120 and the resistor Rcal are connected to the input terminal. Here, the resistance element performs calibration in order to correct the capacitance C of the capacitor C1 that changes due to the temperature change of the meter 200 itself or the dispersion or aging of the component, The branch is a fixed resistor.

The switch 220 selectively connects one of the two resistive sensors 110 and 120 to the output terminal under the control of the processor 240. In other words, when the selector 220 receives the selection command from the processor 240, the switch 220 selects one input channel (temperature measurement channel) among a plurality of input channels to which the temperature measurement data is input.

The voltage output from the frequency generator 220 is divided by the resistance of the resistive sensor 110 or 120 and the capacitor C1 according to the operation of the switch 220. At this time, the voltage V out applied to the resistive sensor 110 or 120 can be calculated by Equation (2).

Figure 112015114290872-pat00002

Where V ref is the output voltage of the frequency generator 210 and R t is the resistance value of the resistive sensor 110 or 120.

The positive input terminal of the amplifier 230 is connected to the output terminal of the switch 220 and the other terminal of the capacitor C1 and the negative input terminal of the amplifier 230 is connected to the output terminal of the amplifier 230.

The amplifier 230 serves as a buffer for temporarily storing the temperature measurement data output through the output terminal of the switch 220. This amplifier 230 may be implemented as an operational amplifier (OP AMP).

The amplifier 230 receives the voltage divided by the resistive sensor 110 or 120 selected by the switch 220 and transmits the divided voltage to the processor 240.

The processor 240 confirms whether the divided voltage (output voltage) delivered from the amplifier 230 matches the target value (e.g., 2.5 V). At this time, the processor 240 confirms whether the output voltage matches the target value within the tolerance range.

The processor 240 calculates a temperature value using the output voltage of the amplifier 230 and the current reference frequency of the frequency generator 210 when the output voltage matches the target value. That is, the processor 240 calculates the resistance value of the resistive sensor 110 or 120 that varies according to the ambient temperature using Equations (1) and (2). Then, the processor 240 calculates the temperature corresponding to the resistance value of the calculated resistive sensor 110 or 120.

On the other hand, the processor 240 checks whether the output voltage exceeds the target value if the output voltage does not match the target value. The processor 240 reduces the reference frequency when the output voltage exceeds the target value and adjusts the output voltage (divided voltage) by the resistive sensor 110 or 120 to reach the target value.

Meanwhile, when the output voltage of the amplifier 230 does not exceed the target value, the processor 240 adjusts the output voltage (divided voltage) by the resistive sensor 110 or 120 to reach the target value by increasing the reference frequency .

In addition, the processor 240 performs the calibration at a predetermined cycle to correct the capacitance C of the capacitor C1 due to a change in the temperature of the measuring instrument 200 itself, a dispersion or aging of the components.

At this time, the processor 240 controls the switch 220 to connect the resistance element Rcal having a predetermined resistance value. That is, the processor 240 switches to the channel for calibration through the control of the switch 220. The processor 240 controls the frequency generator 210 to generate a reference frequency for calibration to check the capacitance C of the capacitor C1. In other words, the processor 240 measures the output voltage by the resistance element Rcal and calculates the capacitance of the capacitor C1 using the measured value.

In the present embodiment, calibration is performed to correct capacitance change due to deterioration of the capacitor C1. However, the necessity of calibration and the execution cycle are different according to application characteristics, and thus, it can be selectively used.

The processor 240 includes a storage medium (not shown) for storing data such as a reference frequency, a target value, and a calibration reference frequency set for each resistive sensor. The storage medium (not shown) may be a memory embedded in the processor 240 or a separately provided memory.

2 is a flowchart illustrating a method of measuring a temperature according to an embodiment of the present invention. In this embodiment, the case where the temperature sensor 100 is composed of two resistive sensors 110 and 120 will be described as an example.

As shown in FIG. 2, the processor 240 transmits a channel selection command to the switch 220 to switch the temperature measurement channel (S110). In other words, the processor 240 selects one of the two resistive sensors 110 and 120 as the temperature measurement channel through the switch 220 control. For example, the processor 240 controls the switch 220 to switch from the first resistive sensor 110 to the second resistive sensor 120.

The processor 240 determines whether an existing reference frequency for the switched channel exists (S120). The processor 240 confirms whether there is a previously used reference frequency corresponding to the resistive sensor 110 or 120 selected as the sensor to be used for the temperature measurement by the switch 220. [

If there is an existing reference frequency corresponding to the switched channel, the processor 240 controls the frequency generator 210 to apply a voltage of a specific waveform corresponding to the existing reference frequency (S130). The processor 240 provides a reference frequency to the frequency generator 210 and the frequency generator 210 generates and applies a voltage of a particular waveform corresponding to the reference frequency to the capacitor C1 and the selected resistive sensor 110 or 120 do. Here, the specific waveform may be a sine wave.

If the existing reference frequency corresponding to the channel switched in S120 does not exist, the processor 240 generates and applies a voltage of a specific waveform according to the reference frequency set in the switched channel (S135). The processor 240 is data at an initial reference frequency corresponding to the resistive sensor 110 or 120 selected by the switch 220 and does not reflect the change in capacitance due to deterioration and aging of the capacitor C1.

The processor 240 confirms whether the divided output voltage for the switched channel coincides with the target value (S140). At this time, the processor 240 confirms whether the divided output voltage and the target value coincide within an allowable error range.

When the divided output voltage and the target value coincide with each other, the processor 240 calculates the temperature using the current reference frequency and the divided output voltage (S150). The processor 240 calculates the temperature by substituting the current reference frequency of the frequency generator 210 and the output voltage according to the temperature detected through the temperature sensor 100 into Equation (1) and Equation (2).

If the output voltage divided by the voltage at step S140 does not match the target value, the processor 240 checks whether the divided output voltage for the switched channel exceeds the target value (S145). The processor 240 detects the divided output voltage according to the resistance value according to the temperature of the selected resistive sensor 110 or 120. That is, the processor 240 detects the voltage across the resistive sensor 110 or 120. Then, the processor 240 compares the detected output voltage with a predetermined target value.

The processor 240 reduces the reference frequency of the frequency generator 210 when the output voltage exceeds the target value (S160). The processor 240 reduces the reference frequency of the frequency generator 210 so that the output voltage reaches the target value.

Meanwhile, the processor 240 increases the reference frequency of the frequency generator 210 if the divided voltage does not exceed the target value (S165). The processor 240 increases the reference frequency of the frequency generator 210 so that the output voltage reaches the target value.

In other words, in S160 and S165, the processor 240 adjusts the reference frequency of the frequency generator 210 so that the divided voltage can reach the target value. Then, the processor 240 stores the adjusted reference frequency in the memory (not shown) together with the current channel information.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. The codes and code segments constituting the computer program may be easily deduced by those skilled in the art. Such a computer program can be stored in a computer-readable storage medium, readable and executed by a computer, thereby realizing an embodiment of the present invention.

100: Temperature sensor
110, 120: Resistive sensor
200: Measuring instrument
210: Frequency generator
220: Switch
230: Amplifier
240: processor

Claims (16)

A frequency generator for generating a voltage of a specific waveform according to a reference frequency,
A capacitor connected to an output terminal of the frequency generator to receive the voltage of the specific waveform,
A temperature sensor for receiving the voltage of the specific waveform and outputting an output voltage according to the temperature,
A switch to which the capacitor and the output terminal are connected and to which the temperature sensor and the input terminal are connected,
And a processor for adjusting the reference frequency to an output voltage according to the temperature and calculating a temperature using the reference frequency and an output voltage according to the temperature,
Wherein the processor corrects the capacitance of the capacitor by using a resistance element connected to an input terminal of the switch.
The method according to claim 1,
The temperature sensor comprises:
And at least one resistive sensor whose resistance value varies with temperature.
3. The method of claim 2,
The resistive sensor comprises:
A negative temperature coefficient (NTC) type or a positive temperature coefficient (PTC) type thermistor.
3. The method of claim 2,
The reference frequency may be,
And the frequency is set for each of the resistance sensors.
3. The method of claim 2,
The reference frequency may be,
And the frequency is set by the processor.
The method according to claim 1,
The processor includes:
And adjusts the impedance of the capacitor by adjusting the reference frequency.
The method according to claim 1,
The switch
And a temperature measuring unit installed between the capacitor and the temperature sensor for switching the temperature measuring channel under the control of the processor.
8. The method of claim 7,
Further comprising an amplifier connected to an output terminal of the switch for transmitting measurement data measured through the temperature measurement channel to the processor.
9. The method of claim 8,
The amplifier includes:
An operational amplifier (OP AMP).
The method according to claim 1,
The processor includes:
And the impedance of the capacitor is calibrated at every predetermined period.
The method according to claim 1,
The processor includes:
And decreases the reference frequency when the detected output voltage exceeds a target value.
The method according to claim 1,
The processor includes:
And increases the reference frequency when the detected output voltage is less than a target value.
Selecting one of the one or more resistive sensors to switch the temperature measurement channel,
Determining whether an existing reference frequency exists after switching the temperature measurement channel,
Generating a voltage of a predetermined waveform of a reference frequency according to a result of checking whether the existing reference frequency exists, and applying the generated voltage to the capacitor and the selected resistive sensor;
Detecting an output voltage according to the temperature of the resistive sensor, and
Adjusting the reference frequency to an output voltage according to the temperature, and calculating a temperature using the frequency of the voltage of the specific waveform and the output voltage,
The capacitance of the capacitor is corrected using a resistance element connected to the input terminal of the switch when the capacitor is connected to the output terminal and the switch is connected to the resistive sensor and the input terminal is controlled to control the switch. Gt;
14. The method of claim 13,
Further comprising the step of generating a voltage of the specific waveform according to a preset reference frequency to the selected resistive sensor and applying the generated voltage to the capacitor and the selected resistive sensor if the existing reference frequency does not exist, Way.
14. The method of claim 13,
In the temperature calculating step,
And decreasing the reference frequency when the output voltage according to the temperature exceeds a target value.
14. The method of claim 13,
In the temperature calculating step,
And increasing the reference frequency when the output voltage according to the temperature is less than a target value.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100210270B1 (en) * 1995-09-26 1999-07-15 티엔디 가부시끼 가이샤 Temperature measuring device having range of wide and narrow error
JP2000088674A (en) * 1998-09-17 2000-03-31 Canon Inc Method and device for measuring environment
JP2013235991A (en) 2012-05-10 2013-11-21 Ulvac Japan Ltd Power feeding device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100210270B1 (en) * 1995-09-26 1999-07-15 티엔디 가부시끼 가이샤 Temperature measuring device having range of wide and narrow error
JP2000088674A (en) * 1998-09-17 2000-03-31 Canon Inc Method and device for measuring environment
JP2013235991A (en) 2012-05-10 2013-11-21 Ulvac Japan Ltd Power feeding device

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