CN109297553B - Constant temperature difference control circuit of MEMS hot film type flow sensor - Google Patents

Constant temperature difference control circuit of MEMS hot film type flow sensor Download PDF

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Publication number
CN109297553B
CN109297553B CN201811359379.XA CN201811359379A CN109297553B CN 109297553 B CN109297553 B CN 109297553B CN 201811359379 A CN201811359379 A CN 201811359379A CN 109297553 B CN109297553 B CN 109297553B
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temperature
detection resistor
temperature detection
current source
sensor
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CN109297553A (en
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任臣
王亚林
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CETC 13 Research Institute
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CETC 13 Research Institute
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/6845—Micromachined devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
    • G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
    • G01F1/69—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element of resistive type
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
    • G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
    • G01F1/696—Circuits therefor, e.g. constant-current flow meters
    • G01F1/698—Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters
    • G01F1/699—Feedback or rebalancing circuits, e.g. self heated constant temperature flowmeters by control of a separate heating or cooling element

Abstract

The invention provides a constant temperature difference control circuit of an MEMS hot film type flow sensor, belonging to the technical field of flow sensors, and the circuit comprises: the device comprises a first temperature detection resistor, a second temperature detection resistor, a heating resistor, a closed loop feedback circuit, a first constant current source and a second constant current source; the first temperature detection resistor is arranged at the air inlet of the sensor, and the heating resistor and the second temperature detection resistor are adjacently arranged in the middle of the sensor; the first constant current source is connected with one end of the first temperature detection resistor, and the second constant current source is connected with one end of the second temperature detection resistor; a first common-connection end of the first constant current source and the first temperature detection resistor is connected to a first input end of the closed-loop feedback circuit, and a second common-connection end of the second constant current source and the second temperature detection resistor is connected to a second input end of the closed-loop feedback circuit; the output end of the closed-loop feedback circuit is connected with the heating resistor, so that the constant temperature difference delta T between the air inlet temperature of the sensor and the temperature of the heating area can be accurately ensured.

Description

Constant temperature difference control circuit of MEMS hot film type flow sensor
Technical Field
The invention belongs to the technical field of flow sensors, and particularly relates to a constant temperature difference control circuit of an MEMS (micro-electromechanical system) hot film type flow sensor.
Background
The MEMS hot film type flow sensor is based on the theory that the exothermic quantity or the endothermic quantity of fluid is in direct proportion to the mass flow of the fluid, which is put forward by Thomas, a heat source is utilized to heat a sensitive element of the sensor, forced convection heat transfer is generated when gas flows in, so that the temperature field of a sensitive device is changed, and a certain functional relation exists between the variation of the temperature field and the gas, thereby measuring the gas flow value.
Referring to fig. 1, fig. 1 is a typical structural diagram of a MEMS hot film type flow sensor, in which a heating resistor 3 and a temperature detecting resistor 4 of the heating resistor are arranged in the middle of the sensor, a flow detecting resistor 2 is symmetrically arranged upstream and downstream of the heating resistor 3, the flow detecting resistor is a thermistor with a positive temperature coefficient, and a temperature adding resistor 1 is arranged at an air inlet. The measurement principle of the sensor is as follows: the heating resistor 3 is electrified to form a heating area, and the temperature of the heating area is 60-110 ℃ higher than the ambient temperature. When no gas flows, the upper temperature field and the lower temperature field of the resistance of the heating area are symmetrically distributed, as shown by a solid line in the figure; when gas flows through the gas flow, the temperature field changes to a state of a dotted line in the graph, the temperature of the upstream detection resistor is reduced due to the gas flow, the resistance is reduced, meanwhile, the heat of the heating area is carried to the downstream by the gas flow, the temperature of the downstream detection resistor is increased, and the resistance is increased. When the temperature difference delta T between the intake temperature and the heating area is always kept constant, namely the sensor works in a constant temperature difference mode, the temperature difference delta T1 generated by the upstream and downstream detection resistors changes along with the change of the gas flow, and the upstream and downstream detection resistors in the sensor form a Wheatstone bridge to convert a temperature difference signal delta T1 caused by the gas flow into a voltage signal. Therefore, a control circuit capable of accurately ensuring that the difference Δ T between the sensor intake air temperature and the heating area temperature is constant is required.
Disclosure of Invention
The invention aims to provide a constant temperature difference control circuit of an MEMS hot film type flow sensor, which can realize a control circuit capable of accurately ensuring that the temperature difference delta T between the air inlet temperature of the sensor and the temperature difference delta T of a heating area is constant.
In order to achieve the above object, the first aspect of the present invention employs the following technical solutions: provided is a constant temperature difference control circuit of a MEMS hot film type flow sensor, comprising: the device comprises a first temperature detection resistor, a second temperature detection resistor, a heating resistor, a closed loop feedback circuit, a first constant current source and a second constant current source;
the first temperature detection resistor is arranged at an air inlet of the sensor, and the heating resistor and the second temperature detection resistor are adjacently arranged in the middle of the sensor;
the first constant current source is connected with one end of the first temperature detection resistor, and the second constant current source is connected with one end of the second temperature detection resistor;
a first common end of the first constant current source and the first temperature detection resistor is connected to a first input end of the closed-loop feedback circuit, and a second common end of the second constant current source and the second temperature detection resistor is connected to a second input end of the closed-loop feedback circuit; and the output end of the closed-loop feedback circuit is connected with the heating resistor.
Further, the closed loop feedback circuit includes: a differential amplifier and a triode;
the non-inverting input end of the differential amplifier is the first input end of the closed-loop feedback circuit, the inverting input end of the differential amplifier is the second input end of the closed-loop feedback circuit, the output end of the differential amplifier is connected with the base electrode of the triode, and the emitter of the triode is the output end of the closed-loop feedback circuit.
Further, the other end of the first temperature detection resistor is grounded.
Further, the other end of the second temperature detection resistor is grounded.
Further, the resistance value R of the first temperature detection resistor1＝R1-0+k1T1Wherein R is1-0Is the resistance value k of the first temperature detection resistor at 0 DEG C1Temperature system for detecting resistance for first temperature, T1Is the sensor inlet temperature.
Further, the resistance value R of the second temperature detection resistor4＝R4-0+k4T2Wherein R is4-0Is the resistance value, k, of the second temperature detection resistor at 0 DEG C4Temperature system for the second temperature detection resistor, T2Is the sensor heating zone temperature.
Further, the first constant current source current is I1The second constant current source current is I2Said R is1-0、R4-0、k1And k4Satisfies the relationship:
R1I1-R4I2＝R1-0I1+k1T1I1-R4-0I2-k4T2I20, wherein T2-T1Δ T, which is the constant temperature difference at the sensor air inlet from the heating zone.
Further, the circuit further comprises an analog-to-digital converter and a filter; the input end of the analog-to-digital converter is connected with the first input end of the closed-loop feedback circuit, the output end of the analog-to-digital converter is connected with the filter, and the digital signal output by the output end of the filter is used for temperature compensation of the rear-stage sensor.
In a second aspect, an embodiment of the present invention further provides an MEMS thermal film type flow sensor, which includes an ASIC chip, where the ASIC chip is provided with the MEMS thermal film type flow sensor constant temperature difference control circuit according to the first aspect.
The MEMS hot film type flow sensor constant temperature difference control circuit provided by the invention has the beneficial effects that: compared with the prior art, the MEMS hot film type flow sensor constant temperature difference control circuit has the advantages that the first temperature detection resistor and the second temperature detection resistor are respectively provided with the two constant current sources, the currents are constant, when the temperature of the air inlet of the sensor and the temperature of the heating resistor heating area are changed, the resistance values of the first temperature detection resistor and the second temperature detection resistor are changed, the voltages input to the first input end and the second input end of the closed loop feedback circuit are changed, the two voltage differences are amplified by the closed loop feedback circuit and fed back to the heating resistor, and the difference value between the temperature of the air inlet of the sensor and the temperature of the heating resistor heating area is constant by controlling the heating resistor. .
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed for the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a MEMS hot film flow sensor according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a temperature difference control circuit of a MEMS hot film type flow sensor according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a constant temperature difference control circuit of a MEMS thermal film type flow sensor according to another embodiment of the present invention.
Wherein, in the figures, the respective reference numerals:
the temperature detection circuit comprises a first temperature detection resistor-100, a second temperature detection resistor-200, a heating resistor-300, a closed loop feedback circuit-400, a first constant current source-500, a second constant current source-600, a differential amplifier-410, a triode-420, an analog-to-digital converter-700 and a filter-800.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Referring to fig. 1 and fig. 2, a constant temperature difference control circuit of the MEMS hot film type flow sensor according to the present invention will be described. The MEMS hot film type flow sensor constant temperature difference control circuit comprises: a first temperature detection resistor 100, a second temperature detection resistor 200, a heating resistor 300, a closed loop feedback circuit 400, a first constant current source 500, and a second constant current source 600.
The first temperature detection resistor 100 is arranged at the air inlet of the sensor (shown in 1 in fig. 1), and the heating resistor 300 and the second temperature detection resistor 200 are adjacently arranged in the middle of the sensor (shown in 3 and 4 in fig. 1);
the first constant current source 500 is connected to one end of the first temperature detection resistor 100, and the second constant current source 600 is connected to one end of the second temperature detection resistor 200;
a first common end of the first constant current source 500 and the first temperature detection resistor 100 is connected to a first input end 401 of the closed-loop feedback circuit 400, and a second common end of the second constant current source 600 and the second temperature detection resistor 200 is connected to a second input end 402 of the closed-loop feedback circuit 400; the output 403 of the closed-loop feedback circuit 400 is connected to the heating resistor 300.
In this embodiment, the first temperature detecting resistor 100 and the second temperature detecting resistor 200 are both temperature sensitive resistors. The first temperature detection resistor 100 is used for measuring the temperature at the air inlet of the sensor, and the second temperature detection resistor 200 is used for measuring the temperature of the heating zone of the heating resistor 300 of the sensor.
It can be known from the above description that, the first temperature detection resistor and the second temperature detection resistor are two constant current sources respectively, the current is constant, when the temperature at the air inlet of the sensor and the temperature at the heating resistor heating area change, the resistance values of the first temperature detection resistor and the second temperature detection resistor change, the voltage input to the first input end and the second input end of the closed-loop feedback circuit changes, the two voltage differences are amplified by the closed-loop feedback circuit and fed back to the heating resistor, and the difference between the temperature at the air inlet of the sensor and the temperature at the heating resistor heating area is constant by controlling the heating resistor.
Further, referring to fig. 2, as an embodiment of the constant temperature difference control circuit of the MEMS hot film type flow sensor provided in the present invention, the closed-loop feedback circuit 400 includes: a differential amplifier 410 and a transistor 420;
the non-inverting input terminal of the differential amplifier 410 is the first input terminal of the closed-loop feedback circuit, the inverting input terminal of the differential amplifier 420 is the second input terminal of the closed-loop feedback circuit, the output terminal of the differential amplifier 410 is connected with the base of the triode 420, and the emitter of the triode 420 is the output terminal of the closed-loop feedback circuit.
From the above description, the differential amplifier and the triode are used for amplifying and feeding back the voltage difference, so that the structure is simple and the cost is low.
Further, referring to fig. 2, the other end of the first temperature detection resistor 100 is grounded. The other end of the second temperature detection resistor 200 is grounded. One end of the heating resistor 300 is connected with the closed-loop feedback circuit 400, and the other end is grounded.
Further, the resistance value R of the first temperature detection resistor1＝R1-0+k1T1Wherein R is1-0Is the resistance value k of the first temperature detection resistor at 0 DEG C1Temperature system for detecting resistance for first temperature, T1Is the sensor inlet temperature.
Resistance R of the second temperature detection resistor4＝R4-0+k4T2Wherein R is4-0Is the resistance value, k, of the second temperature detection resistor at 0 DEG C4Temperature system for the second temperature detection resistor, T2Is the sensor heating zone temperature.
The first constant current source has a current I1The second constant current source current is I2Said R is1-0、R4-0、k1And k4Satisfies the relationship:
R1I1-R4I2＝R1-0I1+k1T1I1-R4-0I2-k4T2I20, wherein T2-T1Δ T, which is the constant temperature difference at the sensor air inlet from the heating zone.
From the above description, it can be seen that by properly designing R1-0、R4-0、k1And k4Thus, the constant temperature difference between the air inlet of the sensor and the heating area can be ensured.
Further, referring to fig. 2 and fig. 3, as a specific embodiment of the constant temperature difference control circuit of the MEMS thermal film type flow sensor provided in the present invention, the constant temperature difference control circuit of the MEMS thermal film type flow sensor further includes: analog-to-digital converter 700 and filter 800. The input end of the analog-to-digital converter 800 is connected with the first input end of the closed-loop feedback circuit 400, the output end of the analog-to-digital converter 700 is connected with the filter 800, and the digital signal output by the output end of the filter 800 is used for temperature compensation of the rear-stage sensor.
In the present embodiment, the analog-to-digital converter 700 is a second-order Σ Δ analog-to-digital converter, which realizes signal conversion.
In this embodiment, the filter 800 is a low-pass filter, such as a CIC filter + IIR filter, and implements down-sampling, respectively, so that the output data amount is reduced and the high-frequency noise is filtered.
In a second aspect, an embodiment of the present invention further provides an MEMS thermal film type flow sensor, which includes an ASIC chip, where the ASIC chip is provided with the above-mentioned MEMS thermal film type flow sensor constant temperature difference control circuit.
In the embodiment, the ASIC chip is an ASIC chip manufactured by a 0.18 μm process and has a miniaturized integrated feature.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (6)

1. A MEMS thermal film flow sensor constant temperature differential control circuit, comprising: the device comprises a first temperature detection resistor, a second temperature detection resistor, a heating resistor, a closed loop feedback circuit, a first constant current source and a second constant current source;
the first temperature detection resistor is arranged at an air inlet of the sensor, and the heating resistor and the second temperature detection resistor are adjacently arranged in the middle of the sensor;
the first constant current source is connected with one end of the first temperature detection resistor, and the second constant current source is connected with one end of the second temperature detection resistor;
a first common end of the first constant current source and the first temperature detection resistor is connected to a first input end of the closed-loop feedback circuit, and a second common end of the second constant current source and the second temperature detection resistor is connected to a second input end of the closed-loop feedback circuit; the output end of the closed loop feedback circuit is connected with the heating resistor;
the resistance value of the first temperature detection resistor is R1＝R1-0+k1T1Wherein R is1-0Is the resistance value k of the first temperature detection resistor at 0 DEG C1Temperature system for detecting resistance for first temperature, T1Is the sensor inlet temperature;
the resistance value of the second temperature detection resistor is R4＝R4-0+k4T2Wherein R is4-0Is the resistance value, k, of the second temperature detection resistor at 0 DEG C4Temperature system for the second temperature detection resistor, T2A temperature for heating a zone for the sensor;
the first constant current source has a current I1The second constant current source current is I2Said R is1-0、R4-0、k1And k4Satisfies the relationship:
R1I1-R4I2＝R1-0I1+k1T1I1-R4-0I2-k4T2I20, wherein T2-T1Δ T, which is the constant temperature difference at the sensor air inlet from the heating zone.
2. The MEMS hot film flow sensor constant temperature differential control circuit of claim 1, wherein the closed loop feedback circuit comprises: a differential amplifier and a triode;
the non-inverting input end of the differential amplifier is the first input end of the closed-loop feedback circuit, the inverting input end of the differential amplifier is the second input end of the closed-loop feedback circuit, the output end of the differential amplifier is connected with the base electrode of the triode, and the emitter of the triode is the output end of the closed-loop feedback circuit.
3. The MEMS hot film flow sensor differential temperature control circuit of claim 1, wherein the other end of the first temperature sensing resistor is grounded.
4. The MEMS hot film flow sensor differential temperature control circuit of claim 1, wherein the second temperature sensing resistor has another end grounded.
5. The MEMS hot film flow sensor constant temperature differential control circuit of any of claims 1 to 4, further comprising an analog to digital converter and a filter; the input end of the analog-to-digital converter is connected with the first input end of the closed-loop feedback circuit, the output end of the analog-to-digital converter is connected with the filter, and the digital signal output by the output end of the filter is used for temperature compensation of the rear-stage sensor.
6. A MEMS thermal film flow sensor comprising an ASIC chip having the MEMS thermal film flow sensor constant temperature differential control circuit of any of claims 1 to 5 disposed thereon.
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CN110274649B (en) * 2019-06-13 2020-09-01 武汉大学 Thermal temperature difference type flow sensor based on MEMS technology and preparation method thereof
CN111323090B (en) * 2020-03-02 2021-12-14 深圳大学 Micro flow sensor based on thermal feedback, airflow measuring system and measuring method
CN112730886A (en) * 2020-12-21 2021-04-30 上海交通大学 Flexible MEMS flow velocity sensor based on amorphous germanium thermal resistor
CN113157008B (en) * 2021-04-01 2022-08-23 青岛芯笙微纳电子科技有限公司 MEMS mass flow controller and control method
CN113670452B (en) * 2021-08-18 2023-05-12 深圳市汇顶科技股份有限公司 Non-contact temperature measuring device, temperature measuring module and electronic equipment therein

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JPS6432120A (en) * 1987-07-29 1989-02-02 Sharp Kk Flow sensor
JP3366818B2 (en) * 1997-01-16 2003-01-14 株式会社日立製作所 Thermal air flow meter
JP3758081B2 (en) * 2001-06-05 2006-03-22 三菱電機株式会社 Thermal flow detector
JP2003279395A (en) * 2002-03-20 2003-10-02 Mitsui Mining & Smelting Co Ltd Flow rate measuring method and flowmeter
JP5209232B2 (en) * 2007-05-24 2013-06-12 アズビル株式会社 Thermal flow meter
CN102141422B (en) * 2010-12-31 2012-03-07 北京航空航天大学 Flow-temperature integrated measurement device for moonlet single-phase fluid thermal control loop

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