CN111174965A - Atmospheric pressure altitude switch temperature compensation system - Google Patents
Atmospheric pressure altitude switch temperature compensation system Download PDFInfo
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- CN111174965A CN111174965A CN202010010634.0A CN202010010634A CN111174965A CN 111174965 A CN111174965 A CN 111174965A CN 202010010634 A CN202010010634 A CN 202010010634A CN 111174965 A CN111174965 A CN 111174965A
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 5
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L9/00—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means
- G01L9/08—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of piezoelectric devices, i.e. electric circuits therefor
- G01L9/085—Measuring steady of quasi-steady pressure of fluid or fluent solid material by electric or magnetic pressure-sensitive elements; Transmitting or indicating the displacement of mechanical pressure-sensitive elements, used to measure the steady or quasi-steady pressure of a fluid or fluent solid material, by electric or magnetic means by making use of piezoelectric devices, i.e. electric circuits therefor with temperature compensating means
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L19/00—Details of, or accessories for, apparatus for measuring steady or quasi-steady pressure of a fluent medium insofar as such details or accessories are not special to particular types of pressure gauges
- G01L19/04—Means for compensating for effects of changes of temperature, i.e. other than electric compensation
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Abstract
The invention relates to the field of air pressure switches, in particular to an air pressure height switch temperature compensation system which is applied to an air pressure height switch and comprises a power supply conversion unit, a temperature control switch and a signal operation circuit; the power supply conversion unit converts the input voltage into output voltage with specified magnitude and provides the output voltage to the temperature control switch and the signal operation circuit; the temperature control switch senses the temperature change of the gas to be detected, is turned on at low temperature and transmits a generated signal to the signal operation circuit, and the signal operation circuit corrects the signal input by the air pressure sensor through a preset temperature correction parameter by using the signal input by the temperature control switch and transmits the corrected signal to the driving unit; the technical scheme solves the problem that the output numerical value precision of a domestic air pressure altitude switch in a working environment of-55-40 ℃ is low.
Description
Technical Field
The invention relates to the field of air pressure switches, in particular to a temperature compensation system of an air pressure height switch.
Background
At present, there is a need for a gas pressure switch suitable for gas pressure detection in the 8km altitude range, which is used as a switch for an oxygen valve, and which switches on a solenoid valve to start oxygen supply when the altitude of an aircraft cabin is above 8km, and switches off the solenoid valve to cut off the oxygen supply when the altitude of the cabin is below 8 km.
The main core component of the air pressure switch is composed of an air pressure sensor and a switch drive. At present, the type of an airborne common air pressure switch in China is a sensor based on a diffused silicon crystal, and the sensor is mostly in the form of other assets such as Feishikal, Honeywell and the like. The control drive circuit of the product mainly adopts a singlechip to carry out temperature compensation and on-off control, and the singlechip which can meet the military-grade requirements is also abroad in many cases. In the process of recent trade battles, the product forbidden transport has great influence on military and industrial products in China. For this reason we have used home-made barometric pressure sensors and analog temperature compensation circuits in this design instead of relying on foreign brands.
According to the requirements: the product needs to realize that height switches from 8150m to 8350m are opened to the ground according to the formula:
the corresponding pressure here is 33.8KPa-34.8KPa, and the closed condition is lower than the open condition by between 100-300m, as shown in fig. 1.
It can be seen that 8250100m of the design requirement corresponds to an error of 500 Pa. Then, the sensor with the accuracy of 0.1 percent within the selected range of 10-110KPa is required to be selected when the type of the sensor is selected. Therefore, in the design, the sensors meeting the requirements are selected, mainly the Haschel MXP series is compared with the domestic sensors, and the comparison result shows that: the domestic sensor has the same parameter performance as the Feichka's sensor in the parameters of measuring range, input voltage, output voltage, overload air pressure, damage air pressure, response time and the like, so the domestic FB001 sensor is selected in the design.
According to the requirements of military product manuals, the temperature of electronic products must be in the range of-55 to 120 ℃, the temperature compensation range of conventional sensors available at home and abroad is generally-40 to 85 ℃, and fig. 2 and 3 are respectively a temperature compensation range of Feichka and a temperature curve of a domestic sensor.
As can be seen from FIG. 3, the domestic sensor mainly makes a primary compensation between-40 ℃ and 85 ℃, and the requirement of-55 ℃ to 85 ℃ for the temperature operation of the altitude pressure switch is still not satisfied, so that a secondary compensation circuit needs to be made between-55 ℃ and 0 ℃ in the sensor, and the requirement of 1% FS in the temperature range of-55 ℃ to 85 ℃ is met.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a temperature compensation system for an air pressure altitude switch, and the technical scheme solves the problem that the output numerical value precision of a domestic air pressure altitude switch in a working environment of-55-40 ℃ is low.
In order to solve the technical problems, the invention provides the following technical scheme:
a temperature compensation system of an air pressure height switch is applied to the air pressure height switch, the air pressure height switch comprises an air pressure sensor and a driving unit, the air pressure sensor senses the pressure change of a detected gas and transmits a generated signal to the driving unit, and the driving unit processes the acquired signal and outputs the signal to an execution element after the processing is finished;
the temperature compensation system comprises a power supply conversion unit, a temperature control switch and a signal operation circuit;
the power supply conversion unit converts the input voltage into output voltage with specified magnitude and provides the output voltage to the temperature control switch and the signal operation circuit;
the temperature control switch senses the temperature change of the measured gas, is turned on at low temperature and transmits a generated signal to the signal operation circuit, and the signal operation circuit corrects the signal input by the air pressure sensor through a preset temperature correction parameter by using the signal input by the temperature control switch and transmits the corrected signal to the driving unit.
Preferably, the temperature control switch comprises a temperature sensor, a second signal comparator and a switch; the temperature sensor senses the temperature change of the gas to be detected, transmits the generated signal to the signal operation circuit through the switch, and simultaneously transmits the generated signal to the second signal comparison circuit; the second signal comparator compares signals input by the temperature sensor and sends an opening and closing signal to the switch.
Preferably, the power conversion unit comprises a power supply, a common mode filter, a voltage regulator tube, a third resistor, a first differential mode inductor, a second differential mode inductor and a third differential mode inductor;
the positive terminal of the power supply is electrically connected with the input end of the voltage-stabilizing tube through the first differential mode inductor, the third resistor, the first core wire external terminal of the common mode filter and the second core wire external terminal of the common mode filter in sequence;
the negative end of the power supply is electrically connected with the ground wire sequentially through the second differential mode inductor, the first shielding layer external terminal of the common mode filter and the second shielding layer external terminal of the common mode filter;
the earth terminal of the voltage-stabilizing tube is electrically connected with the earth wire, and the temperature control switch and the positive terminal of the signal operation circuit are electrically connected with the output terminal of the voltage-stabilizing tube.
Preferably, the power conversion unit further includes a voltage dependent resistor and a self-recovery fuse, two ends of the voltage dependent resistor are electrically connected to two ends of the power supply, and two ends of the self-recovery fuse are electrically connected to an input end of the voltage dependent resistor and an input end of the first differential mode inductor.
Preferably, a diode is connected in series between the output end of the self-recovery fuse and the input end of the first differential-mode inductor, and the input end of the diode is electrically connected with the output end of the self-recovery fuse.
Preferably, at least one capacitor is connected in series between the diode and the first differential-mode inductor, between the third resistor and the common-mode filter, between the common-mode filter and the voltage regulator tube, between the voltage regulator tube and the third differential-mode inductor, and between the positive terminal of the temperature control switch and the signal operation circuit and the third differential-mode inductor, and is electrically connected with a ground wire.
Preferably, an ESD protection diode is connected in series between the third resistor and the common-mode filter and between the positive terminal of the temperature control switch and the signal operation circuit and the third differential-mode inductor, and is electrically connected to the ground, and an input end of the ESD protection diode is electrically connected to the ground.
Preferably, a third low-pass filter capacitor and a second resistor are sequentially connected in series between the diode and the first differential-mode inductor and electrically connected with the casing, and a fourth low-pass filter capacitor and an earth wire are connected in series at the input end of the second resistor.
Preferably, the second signal comparison circuit comprises a second signal comparator, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a twelfth low-pass filter capacitor and a thirteenth low-pass filter capacitor, the output end of the temperature sensor is electrically connected with the negative end of the second signal comparator through the fourth resistor and the fifth resistor in sequence, one end of the twelfth low-pass filter capacitor is electrically connected with the joint of the fourth resistor and the fifth resistor, one end of the thirteenth low-pass filter capacitor is electrically connected with the joint of the fifth resistor and the second signal comparator, and the other ends of the twelfth low-pass filter capacitor and the thirteenth low-pass filter capacitor are electrically connected with the ground wire; the output end of the power conversion unit is electrically connected with the positive end of the second signal comparator through a sixth resistor, the output end of the second signal comparator is electrically connected with the input end of the driving unit through an eighth resistor, and two ends of the seventh resistor are respectively electrically connected with the negative end and the output end of the second signal comparator.
Preferably, the second signal comparator is a hysteresis comparator.
Compared with the prior art, the invention has the beneficial effects that:
the power supply conversion unit converts the input voltage of the wire harness terminal into output voltage with specified magnitude and provides the output voltage to the air pressure sensor, the driving unit, the temperature control switch and the signal operation circuit; the existing domestic air pressure sensor can only realize the requirement of outputting a high-precision numerical value in a working environment at the temperature of-40-85 ℃, but cannot realize the requirement of outputting the high-precision numerical value in a working environment at the temperature of-55-85 ℃, so that secondary temperature compensation is required to be carried out on a signal output by the air pressure sensor, when the air temperature is 0-85 ℃, a signal operation circuit directly transmits the signal input by the air pressure sensor to a driving unit, when the air temperature is-55-0 ℃, a temperature control switch is turned on and outputs an air temperature signal to the signal operation circuit, and the signal operation circuit carries out compensation correction on the signal input by the air pressure sensor through a preset temperature correction parameter by utilizing the signal input by the temperature control switch; the preset temperature correction parameter obtaining method comprises the following steps: firstly, testing and recording the gas pressure obtained by a gas pressure sensor under different temperature conditions; wherein the standard temperature is T0, and the test value of the air pressure sensor is P0; t1, T2, T3 and T4 are different temperature values, and test values P1, P2, P3 and P4 of the air pressure sensors at T1, T2, T3 and T4 are recorded; according to the formula Pm ═ AxTm + B; obtaining a value of the temperature correction parameter A, B by using a least square fitting algorithm; fitting the pressure sensor test value at the Tm temperature to a pressure value at the standard temperature of T0, and then according to the formula P, obtaining a pressure value of Pm-Ax (Tm-T0); obtaining a pressure test value after secondary temperature compensation; when pressure monitoring is formally started, the signal operation circuit calls a temperature correction parameter A, B corresponding to the gas sensor to perform secondary temperature compensation correction on gas pressure data to obtain a pressure value after secondary temperature compensation, wherein the pressure value after the secondary temperature compensation is a high-precision and high-stability numerical value; and the signal operation circuit transmits the corrected signal to the driving unit.
Compared with the prior art, the invention meets the requirement that the domestic air pressure altitude switch outputs high-precision numerical values in the working environment of-55-85 ℃.
Drawings
FIG. 1 is a pressure error curve;
FIG. 2 is a range of temperature compensation for a Freescale sensor;
FIG. 3 is a graph of FB001 sensor temperature;
FIG. 4 is a schematic view of a pneumatic height switch of the present invention;
FIG. 5 is a diagram of a barometric altitude switch temperature compensation system of the present invention;
FIG. 6 is a voltage conversion circuit according to the present invention;
FIG. 7 shows a voltage regulator circuit according to the present invention;
FIG. 8 is a signal comparison circuit of the present invention;
FIG. 9 is an isolated driver circuit of the present invention;
the reference numbers in the figures are:
t1-common mode filter;
RV 1-piezo-resistor; r2 — second resistance; r3 — third resistance; r4-fourth resistor; r5-fifth resistor; r6-sixth resistance; r7-rent at seventh point; r8 — eighth resistance;
f1 — self-healing fuse;
d1-diode; d2 — first ESD protection diode; d3 — a second ESD protection diode;
l1 — first differential-mode inductance; l2 — second differential-mode inductance; l3 — third differential-mode inductance;
c1 — first low-pass filter capacitance; c2 — second low-pass filter capacitance; c3 — third low-pass filter capacitance; c4-fourth low-pass filter capacitance; c5 — fifth low-pass filter capacitance; c6 — sixth low-pass filter capacitance; c7-seventh low-pass filter capacitance; c8 — eighth low-pass filter capacitance; c9 — ninth low-pass filter capacitor; c1-tenth low-pass filter capacitance; c11 — eleventh low-pass filter capacitance; c12 — twelfth low-pass filter capacitance; c13-thirteenth low-pass filter capacitor;
U1B-second signal comparator.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further 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.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
As shown in fig. 4, the barometric altitude switch includes a housing, a hardware circuit and a wire harness terminal, wherein the hardware circuit is fixedly installed inside the housing, and the wire harness terminal penetrates through the housing and is electrically connected with the hardware circuit;
the hardware circuit comprises a circuit board, and an air pressure acquisition unit, a temperature compensation unit and a driving unit which are integrated on the circuit board;
the wire harness terminal is used for transmitting external power to the hardware circuit and outputting signals of the driving unit to the outside;
the air pressure acquisition unit senses the pressure change of the detected air and transmits the generated signal to the temperature compensation unit;
the temperature acquisition unit senses the temperature change of the gas to be detected, transmits the generated signal to the temperature compensation unit,
the temperature compensation unit compensates and corrects the signal input by the gas acquisition unit through the signal input by the temperature acquisition unit, and then transmits the corrected signal to the driving unit;
the driving unit processes the acquired signals and outputs the signals through the wiring harness terminal after the processing is finished.
A housing for mounting a circuit board and electronic components; the air pressure acquisition unit is used for converting the air pressure at the current height into a voltage signal; the temperature acquisition unit is used for converting the current gas temperature into a voltage signal; the temperature compensation unit is used for compensating and correcting the signal input by the gas acquisition unit by using the signal input by the temperature acquisition unit and the corresponding temperature correction parameter, and outputting a high-precision and high-stability numerical value to the driving unit; and the driving unit is used for processing the acquired signals and outputting the signals after the processing is finished.
The air pressure acquisition unit is a silicon piezoresistive pressure sensor, the temperature acquisition unit comprises a first temperature sensor, and the temperature compensation unit comprises a primary temperature compensation circuit; the first temperature sensor senses the temperature change of the gas to be detected and transmits a generated signal to the primary temperature compensation circuit; the primary temperature compensation circuit compensates and corrects the signal input by the gas acquisition unit through the signal input by the first temperature sensor, and then transmits the corrected signal to the driving unit.
The silicon piezoresistive pressure sensor is used for sensing the pressure change of the gas to be detected and transmitting a generated signal to the primary temperature compensation circuit; the first temperature sensor is used for collecting the ambient temperature and transmitting a signal to the primary temperature compensation circuit; and the primary temperature compensation circuit is used for realizing circuit balance and temperature compensation and transmitting the corrected data to the driving unit.
The temperature acquisition unit also comprises a second temperature sensor, and the temperature compensation unit also comprises a secondary temperature compensation circuit; the second temperature sensor senses the temperature change of the gas to be detected and transmits the generated signal to the secondary temperature compensation circuit; the secondary temperature compensation circuit compensates and corrects the signal input by the primary temperature compensation circuit through the signal input by the second temperature sensor, and then transmits the corrected signal to the driving unit.
When the temperature is 0-85 ℃, the secondary temperature compensation circuit directly transmits the signal input by the primary temperature compensation circuit to the driving unit, when the temperature is-55-0 ℃, the secondary temperature compensation circuit performs compensation correction on the signal input by the primary temperature compensation circuit through the signal input by the second temperature sensor, and then transmits the corrected signal to the driving unit, so that the requirement of outputting a high-precision numerical value in a working environment of the air pressure acquisition unit at the temperature of-55-85 ℃ is met.
The air pressure acquisition unit is an air pressure sensor, and the temperature acquisition unit comprises a secondary temperature compensation circuit; the air pressure sensor senses the pressure change of the measured gas and transmits the generated signal to the secondary temperature compensation circuit; the second temperature sensor senses the temperature change of the gas to be detected and transmits the generated signal to the secondary temperature compensation circuit; the secondary temperature compensation circuit compensates and corrects the signal input by the air pressure sensor through the signal input by the second temperature sensor, and then transmits the corrected signal to the driving unit.
Because the existing domestic air pressure sensor internally comprises the silicon piezoresistive pressure sensor, the first temperature sensor and the primary temperature compensation circuit, the existing domestic air pressure sensor can be directly purchased for the combination of the silicon piezoresistive pressure sensor, the first temperature sensor and the primary temperature compensation circuit; meanwhile, the existing domestic air pressure sensor can only meet the requirement of outputting high-precision numerical values in a working environment at-40-85 ℃, but cannot meet the requirement of outputting high-precision numerical values in a working environment at a temperature of-55-85 ℃, so that the second temperature sensor and the secondary temperature compensation circuit are required to carry out secondary temperature compensation on signals output by the air pressure sensor, when the air temperature is 0-85 ℃, the secondary temperature compensation circuit directly transmits signals input by the air pressure sensor to the driving unit, when the air temperature is-55-0 ℃, the secondary temperature compensation circuit carries out compensation and correction on the signals input by the air pressure sensor through the signals input by the second temperature sensor, and then transmits the corrected signals to the driving unit, thereby meeting the requirement of outputting high-precision numerical values in a working environment at a temperature of-55-85 ℃ of the air pressure acquisition unit.
The shell is made of aviation aluminum.
The aviation aluminum product can form good shielding, avoids external environment to the influence of internal circuit.
The dielectric material of the circuit board is FR 4.
The FR4 epoxy glass fiber cloth substrate has higher mechanical property, dimensional stability, impact resistance and moisture resistance than a paper substrate, has excellent electrical property, higher working temperature and small influence of the environment on the performance, and is suitable for manufacturing double-sided PCBs.
Compared with the air pressure sensor with the primary temperature compensation circuit and the secondary temperature compensation circuit, the air pressure sensor is improved, and the temperature compensation system formed by the second temperature sensor and the secondary temperature compensation circuit is easier to modify, so that the temperature compensation system of the air pressure sensor made in China is preferably researched and developed.
A temperature compensation system for a barometric altitude switch, as shown in fig. 5, is applied to the barometric altitude switch;
the temperature compensation signal processing unit comprises a power supply conversion unit, a temperature control switch and a signal operation circuit;
the power supply conversion unit converts the input voltage into output voltage with specified magnitude and provides the output voltage to the air pressure sensor, the temperature control switch, the signal operation circuit and the driving unit;
the temperature control switch senses the temperature change of the measured gas, is turned on at low temperature and transmits a generated signal to the signal operation circuit, and the signal operation circuit corrects the signal input by the air pressure sensor through a preset temperature correction parameter by using the signal input by the temperature control switch and transmits the corrected signal to the driving unit.
The power supply conversion unit converts the input voltage of the wire harness terminal into output voltage with specified magnitude and provides the output voltage to the air pressure sensor, the driving unit, the temperature control switch and the signal operation circuit;
the existing domestic air pressure sensor can only realize the requirement of outputting a high-precision numerical value in a working environment at the temperature of-40-85 ℃, but cannot realize the requirement of outputting the high-precision numerical value in a working environment at the temperature of-55-85 ℃, so that secondary temperature compensation is required to be carried out on a signal output by the air pressure sensor, when the air temperature is 0-85 ℃, a signal operation circuit directly transmits the signal input by the air pressure sensor to a driving unit, when the air temperature is-55-0 ℃, a temperature control switch is turned on and outputs an air temperature signal to the signal operation circuit, and the signal operation circuit carries out compensation correction on the signal input by the air pressure sensor through a preset temperature correction parameter by utilizing the signal input by the temperature control switch;
the preset temperature correction parameter obtaining method comprises the following steps: firstly, testing and recording the gas pressure obtained by a gas pressure sensor under different temperature conditions; wherein the standard temperature is T0, and the test value of the air pressure sensor is P0; the common-mode filters T1, T2, T3 and T4 are different temperature values, and air pressure sensor test values P1, P2, P3 and P4 of the common-mode filters T1, T2, T3 and T4 are recorded; according to the formula Pm ═ AxTm + B; obtaining a value of the temperature correction parameter A, B by using a least square fitting algorithm;
fitting the pressure sensor test value at the Tm temperature to a pressure value at the standard temperature of T0, and then according to the formula P, obtaining a pressure value of Pm-Ax (Tm-T0); obtaining a pressure test value after secondary temperature compensation; when pressure monitoring is formally started, the signal operation circuit calls a temperature correction parameter A, B corresponding to the gas sensor to perform secondary temperature compensation correction on gas pressure data to obtain a pressure value after secondary temperature compensation, wherein the pressure value after the secondary temperature compensation is a high-precision and high-stability numerical value;
the signal operation circuit transmits the corrected signal to the driving unit, so that the requirement that the air pressure height switch outputs a high-precision numerical value in a working environment at the temperature of-55-85 ℃ is met.
The driving unit comprises a first signal comparison circuit and an isolation driving circuit, the first signal comparison circuit processes signals input by the temperature compensation unit and outputs the signals to the isolation driving circuit after the signals are processed, and the isolation driving circuit outputs the signals through a wire harness terminal.
The first signal comparison circuit is used for comparing a signal input by the temperature compensation unit with a preset threshold value, outputting a high level or a low level to the isolation driving circuit according to a comparison result, and outputting a signal through the wiring harness terminal according to the level of the input signal, so that the execution unit is started or closed.
The temperature control switch comprises a temperature sensor, a second signal comparator and a switch; the temperature sensor senses the temperature change of the gas to be detected, transmits the generated signal to the signal operation circuit through the switch, and simultaneously transmits the generated signal to the second signal comparison circuit; the second signal comparator compares signals input by the temperature sensor and sends an opening and closing signal to the switch.
Under the normal temperature state, the switch is closed, and the signal operation circuit directly transmits the signal input by the air pressure sensor to the driving unit; when the ambient temperature is extremely high, the signal output by the temperature sensor exceeds a preset threshold value of the second signal comparator, the second signal comparator starts the switch, the temperature sensor outputs a signal to the signal operation circuit through the switch, and the signal operation circuit performs secondary temperature compensation on the signal input by the air pressure sensor.
As shown in fig. 6 and 7, the power conversion unit includes a power supply, a common mode filter T1, a voltage regulator tube, a third resistor R3, a first differential-mode inductor L1, a second differential-mode inductor L2, and a third differential-mode inductor L3;
the positive terminal of the power supply is electrically connected with the input end of the voltage regulator tube through a first differential mode inductor L1, a third resistor R3, a first core wire external terminal of a common mode filter T1 and a second core wire external terminal of a common mode filter T1 in sequence;
the negative end of the power supply is electrically connected with the ground wire sequentially through a second differential mode inductor L2, a first shielding layer external terminal of the common mode filter T1 and a second shielding layer external terminal of the common mode filter T1;
the earth terminal of the voltage-stabilizing tube is electrically connected with the earth wire, and the temperature control switch and the positive terminal of the signal operation circuit are electrically connected with the output terminal of the voltage-stabilizing tube.
In order to improve the sampling precision, the reference voltage needs a low ripple factor, the voltage regulator tube is used for converting 16V voltage into 5V, and the common mode filter T1 is used for filtering common mode electromagnetic interference on a signal line, and simultaneously inhibiting the common mode filter from emitting electromagnetic interference outwards, so that the normal work of other electronic equipment in the same electromagnetic environment is prevented from being influenced; the first differential mode inductor L1, the second differential mode inductor L2 and the third differential mode inductor L3 are used for isolating alternating current coefficients to achieve the effect of reducing voltage ripples; the third resistor R3 is a high-precision resistor, and high-precision conversion of signals is realized.
The power conversion unit further comprises a voltage dependent resistor RV1 and a self-recovery fuse F1, two ends of the voltage dependent resistor RV1 are electrically connected with two ends of a power supply respectively, and two ends of the self-recovery fuse F1 are electrically connected with an input end of the voltage dependent resistor RV1 and an input end of the first differential mode inductor L1 respectively.
The voltage dependent resistor RV1 is mainly used for voltage clamping when the circuit bears overvoltage, and absorbing redundant current to protect sensitive devices. Therefore, the voltage is controlled within a reasonable range, overvoltage is prevented, and the overvoltage protection function is realized; the self-recovery fuse F1 is used for forming a high-resistance state along with the continuous rise of current when the circuit has a fault or an abnormality, thereby automatically disconnecting the circuit, preventing the raised current from possibly damaging some important devices or valuable devices in the circuit and simultaneously preventing the circuit from being burnt to cause fire, and after the fault is eliminated, the self-recovery fuse is recovered to be in a low-resistance state, thereby completing the protection of the circuit without manual replacement.
A diode D1 is connected in series between the output end of the self-recovery fuse F1 and the input end of the first differential-mode inductor L1, and the input end of the diode D1 is electrically connected with the output end of the self-recovery fuse F1.
When the power supply is connected reversely, the diode D1 presents high impedance, thereby realizing the protection function when the power supply is connected reversely.
At least one capacitor is connected in series between the diode D1 and the first differential-mode inductor L1, between the third resistor R3 and the common-mode filter T1, between the common-mode filter T1 and the voltage regulator tube, between the voltage regulator tube and the third differential-mode inductor L3, and between the positive terminal of the temperature control switch and the signal operation circuit and the third differential-mode inductor L3, and the capacitors are electrically connected with the ground wire.
A first low-pass filter capacitor C1 and a second low-pass filter capacitor C2 are connected in series between the diode D1 and the first differential mode inductor L1 and are electrically connected with the ground wire, a fifth low-pass filter capacitor C5 is connected in series between the third resistor R3 and the common mode filter T1 and is electrically connected with the ground wire, a sixth low-pass filter capacitor C6, a seventh low-pass filter capacitor C7 and an eighth low-pass filter capacitor C8 are connected in series between the common mode filter T1 and the voltage regulator tube and are electrically connected with the ground wire, a ninth low-pass filter capacitor C9 and a tenth low-pass filter capacitor C1 are connected in series between the voltage regulator tube and the third differential mode inductor L3 and are electrically connected with the ground wire, an eleventh low-pass filter capacitor C11 is connected in series between the positive electrode end of the temperature control switch and the signal arithmetic circuit and the third differential mode inductor L3 and is electrically connected with the ground wire, and the first low-pass filter capacitor C1, the second low-pass filter capacitor C2, the fifth low-pass filter capacitor C, The eighth low-pass filter capacitor C8, the ninth low-pass filter capacitor C9, the tenth low-pass filter capacitor C1 and the eleventh low-pass filter capacitor C11 are all low-pass filter capacitors, and are used for suppressing the influence of high-frequency signals on the back-end circuit.
An ESD protection diode is connected in series between the third resistor R3 and the common-mode filter T1 and between the positive terminal of the temperature control switch and the signal operation circuit and the third differential-mode inductor L3 and is electrically connected with the ground wire, and the input end of the ESD protection diode is electrically connected with the ground wire.
A first ESD protection diode D2 is connected in series between the third resistor R3 and the common-mode filter T1 and is electrically connected with the ground wire, a second ESD protection diode D3 is connected in series between the positive end of the temperature control switch and signal operation circuit and the third differential-mode inductor L3 and is electrically connected with the ground wire, and the ESD protection diodes realize the ESD protection function of 25KV5 KV.
A third low-pass filter capacitor C3 and a second resistor R2 are sequentially connected in series between the diode D1 and the first differential-mode inductor L1 and electrically connected with the chassis, and a fourth low-pass filter capacitor C4 is connected in series at the input end of the second resistor R2 and electrically connected with the ground wire.
The second resistor R2 is a high-precision resistor, the third low-pass filter capacitor C3 and the fourth low-pass filter capacitor C4 are low-pass filter capacitors, and the second resistor R2, the third low-pass filter capacitor C3 and the fourth low-pass filter capacitor C4 are used for grounding of the machine shell, so that static electricity accumulation is prevented.
The first signal comparison circuit and the second signal comparison circuit have the same structure, the output end of the first signal comparison circuit is communicated with the isolation driving circuit, and the output end of the second signal comparison circuit is communicated with the switch.
As shown in fig. 8, the second signal comparing circuit includes a second signal comparator U1B, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a twelfth low-pass filter capacitor C12 and a thirteenth low-pass filter capacitor C13, the output end of the temperature sensor is electrically connected to the negative terminal of the second signal comparator U1B through the fourth resistor R4 and the fifth resistor R5 in sequence, one end of the twelfth low-pass filter capacitor C12 is electrically connected to the connection between the fourth resistor R4 and the fifth resistor R5, one end of the thirteenth low-pass filter capacitor C13 is electrically connected to the connection between the fifth resistor R5 and the second signal comparator U1B, and the other ends of the twelfth low-pass filter capacitor C12 and the thirteenth low-pass filter capacitor C13 are electrically connected to the ground; the output end of the power conversion unit is electrically connected with the positive end of the second signal comparator U1B through a sixth resistor R6, the output end of the second signal comparator U1B is electrically connected with the input end of the driving unit through an eighth resistor R8, and two ends of the seventh point resistor R7 are respectively and electrically connected with the negative end and the output end of the second signal comparator U1B.
The second signal comparator U1B compares signals input by the temperature sensor and outputs a high level or is turned off, and the fourth resistor R4, the fifth resistor R5, the twelfth low-pass filter capacitor C12 and the thirteenth low-pass filter capacitor C13 realize two low-pass filtering functions, thereby reducing the interference of the signals.
The first signal comparator and the second signal comparator are hysteresis comparators.
The hysteresis comparator is characterized in that the hysteresis comparator has two thresholds which are not equal, the transmission characteristic of the hysteresis comparator has the shape of a hysteresis curve, and the hysteresis comparator is used for eliminating the oscillation opening and closing of a switch caused by unstable target high temperature.
As shown in fig. 9, the isolation driving circuit includes a photocoupler relay, pin 1 of the photocoupler relay is electrically connected to the output end of the first signal comparing circuit, pin 3 of the photocoupler relay is electrically connected to the ground, pin 5 of the photocoupler is connected to the negative electrode of the power supply, and pin 4 and pin 6 of the photocoupler are electrically connected to the zero line end of the actuator.
Keep apart drive circuit and be used for realizing low limit control, when keeping apart drive circuit's 1 foot input high level, trigger switching on of opto-coupler to realize opening of MOS pipe, switch on of output low level control circuit, thereby intercommunication executive component's zero line end and the intercommunication of power negative pole, opto-coupler relay realizes the isolation, avoids this switch to external circuit's influence.
The working principle of the invention is as follows:
the shell is made of aviation aluminum and used for mounting a circuit board and electronic components, so that good shielding can be formed, and the influence of the external environment on an internal circuit is avoided; the air pressure sensor is used for converting the air pressure at the current height into a voltage signal; the second temperature sensor is used for converting the current gas temperature into a voltage signal; the secondary temperature compensation circuit is used for compensating and correcting the signal input by the air pressure sensor by using the signal input by the second temperature sensor and the corresponding temperature correction parameter; when the temperature is 0-85 ℃, the secondary temperature compensation circuit directly transmits a signal input by the air pressure sensor to the hysteresis comparator; when the temperature is-55-0 ℃, the secondary temperature compensation circuit compensates and corrects the signal input by the air pressure sensor through the signal input by the second temperature sensor, and then transmits the corrected signal to the hysteresis comparator; the hysteresis comparator compares a signal input by the temperature compensation unit with a preset threshold value, outputs a high level or a low level to the optocoupler relay according to a comparison result, and the optocoupler relay connects or disconnects a circuit of the execution unit through the wiring harness terminal according to the level of the input signal.
Claims (10)
1. A temperature compensation system of an air pressure height switch is applied to the air pressure height switch, the air pressure height switch comprises an air pressure sensor and a driving unit, the air pressure sensor senses the pressure change of a detected gas and transmits a generated signal to the driving unit, and the driving unit processes the acquired signal and outputs the signal to an execution element after the processing is finished;
the temperature compensation system is characterized by comprising a power supply conversion unit, a temperature control switch and a signal operation circuit;
the power supply conversion unit converts the input voltage into output voltage with specified magnitude and provides the output voltage to the temperature control switch and the signal operation circuit;
the temperature control switch senses the temperature change of the measured gas, is turned on at low temperature and transmits a generated signal to the signal operation circuit, and the signal operation circuit corrects the signal input by the air pressure sensor through a preset temperature correction parameter by using the signal input by the temperature control switch and transmits the corrected signal to the driving unit.
2. The barometric altitude switch temperature compensation system of claim 1, wherein the temperature controlled switch comprises a temperature sensor, a second signal comparator and a switch; the temperature sensor senses the temperature change of the gas to be detected, transmits the generated signal to the signal operation circuit through the switch, and simultaneously transmits the generated signal to the second signal comparison circuit; the second signal comparator compares signals input by the temperature sensor and sends an opening and closing signal to the switch.
3. A barometric altitude switch temperature compensation system according to claim 3, wherein the power conversion unit comprises a power supply, a common mode filter (T1), a voltage regulator, a third resistor (R3), a first differential mode inductor (L1), a second differential mode inductor (L2), and a third differential mode inductor (L3);
the positive terminal of the power supply is electrically connected with the input end of the voltage regulator tube through a first differential mode inductor (L1), a third resistor (R3), a first core wire external terminal of a common mode filter (T1) and a second core wire external terminal of the common mode filter (T1) in sequence;
the negative end of the power supply is electrically connected with the ground wire sequentially through a second differential mode inductor (L2), a first shielding layer external terminal of the common mode filter (T1) and a second shielding layer external terminal of the common mode filter (T1);
the earth terminal of the voltage-stabilizing tube is electrically connected with the earth wire, and the temperature control switch and the positive terminal of the signal operation circuit are electrically connected with the output terminal of the voltage-stabilizing tube.
4. A barometric altitude switch temperature compensation system according to claim 3, wherein said power conversion unit further comprises a voltage dependent resistor (RV1) and a self-recovery fuse (F1), two ends of said voltage dependent resistor (RV1) are electrically connected to two ends of said power supply, two ends of said self-recovery fuse (F1) are electrically connected to said input end of said voltage dependent resistor (RV1) and said input end of said first differential mode inductor (L1).
5. A barometric altitude switch temperature compensation system according to claim 4, wherein a diode (D1) is connected in series between the output of the self-recovery fuse (F1) and the input of the first differential-mode inductor (L1), and the input of the diode (D1) is electrically connected to the output of the self-recovery fuse (F1).
6. A barometric altitude switch temperature compensation system according to claim 5, wherein at least one capacitor is connected in series between the diode (D1) and the first differential mode inductor (L1), between the third resistor (R3) and the common mode filter (T1), between the common mode filter (T1) and the voltage regulator tube, between the voltage regulator tube and the third differential mode inductor (L3), and between the positive terminal of the temperature control switch and the signal operation circuit and the third differential mode inductor (L3) to be electrically connected with the ground line.
7. A barometric altitude switch temperature compensation system according to claim 6, wherein an ESD protection diode is connected in series between the third resistor (R3) and the common mode filter (T1), and between the positive terminal of the temperature control switch and the signal operation circuit and the third differential mode inductor (L3) to be electrically connected to the ground, and the input terminal of the ESD protection diode is electrically connected to the ground.
8. A barometric altitude switch temperature compensation system according to claim 7, wherein a third low-pass filter capacitor (C3) and a second resistor (R2) are connected in series between the diode (D1) and the first differential mode inductor (L1) in sequence and electrically connected with the housing, and a fourth low-pass filter capacitor (C4) is connected in series with the input end of the second resistor (R2) and electrically connected with the ground.
9. A barometric altitude switch temperature compensation system according to claim 8, wherein the second signal comparison circuit comprises a second signal comparator (U1B), a fourth resistor (R4), a fifth resistor (R5), a sixth resistor (R6), a seventh node (R7), an eighth resistor (R8), a twelfth low-pass filter capacitor (C12) and a thirteenth low-pass filter capacitor (C13), wherein the output end of the temperature sensor is electrically connected with the negative end of the second signal comparator (U1B) through the fourth resistor (R4) and the fifth resistor (R5) in sequence, one end of the twelfth low-pass filter capacitor (C12) is electrically connected with the connection position of the fourth resistor (R4) and the fifth resistor (R5), one end of the thirteenth low-pass filter capacitor (C13) is electrically connected with the connection position of the fifth resistor (R5) and the second signal comparator (U1B), and the other ends of the twelfth low-pass filter capacitor (C12) and the thirteenth low-pass filter capacitor (C13) are electrically connected with the ground wire; the output end of the power conversion unit is electrically connected with the positive end of the second signal comparator (U1B) through a sixth resistor (R6), the output end of the second signal comparator (U1B) is electrically connected with the input end of the driving unit through an eighth resistor (R8), and two ends of the seventh point (R7) are respectively and electrically connected with the negative end and the output end of the second signal comparator (U1B).
10. A barometric altitude switch temperature compensation system according to claim 9, wherein the second signal comparator is a hysteresis comparator.
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| CN202010010634.0A CN111174965A (en) | 2020-01-06 | 2020-01-06 | Atmospheric pressure altitude switch temperature compensation system |
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| CN202010010634.0A CN111174965A (en) | 2020-01-06 | 2020-01-06 | Atmospheric pressure altitude switch temperature compensation system |
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Application publication date: 20200519 |