PM2.5 sensor high and low temperature compensation method

Abstract

The invention relates to the technical field of PM2.5 sensors, in particular to a PM2.5 sensor high and low temperature compensation method, which comprises the following steps of: respectively starting normal temperature calibration, high temperature calibration and low temperature calibration in a calibration bin, circularly detecting whether Grimm reaches a set sampling point or not in the calibration process, closing a stirring mechanism when five concentration values are approached, and stopping the stirring mechanism when five concentration values are approached; standing for two minutes when reaching the calibration points + / -10, then recording the number of particles corresponding to the five calibration points, writing the recorded numerical values into equipment, and storing the recorded numerical values; based on the normal temperature calibration result, the high temperature calibration result and the low temperature calibration result, a compensation function between the high temperature and the normal temperature and a compensation function between the low temperature and the normal temperature are constructed respectively; the temperature value transmitted by the NTC in the product is substituted into a corresponding compensation function, a PM2.5 concentration compensation value is calculated, and the PM2.5 concentration sampling value output by the product is added to the PM2.5 concentration compensation value to obtain a compensated PM2.5 concentration sampling value; according to the invention, the stability and accuracy of measurement of the PM2.5 sensor in different temperature environments can be ensured.

Description

Technical Field

[0001] This invention relates to the field of PM2.5 sensor technology, and in particular to a method for high and low temperature compensation of PM2.5 sensors. Background Technology

[0002] A PM2.5 sensor (also known as a dust sensor) is a measuring device used to measure and monitor fine particulate matter (PM) in the air, with a diameter of less than 2.5 micrometers. Most high-end versions of cars produced by current OEMs include PM2.5 sensors to monitor the real-time status of fine particulate matter inside and outside the vehicle, and to control the air conditioning system by transmitting the real-time values ​​to the air conditioning assembly.

[0003] At normal temperature, PM2.5 sensors can accurately measure fine particulate matter in the air. However, at high and low temperatures, the internal components of the PM2.5 sensor are affected by temperature changes, causing deviations in the measured PM2.5 concentration values. This affects the measurement stability of the PM2.5 sensor under different temperature conditions and makes it impossible to provide the air conditioning assembly with accurate and effective PM2.5 concentration values.

[0004] To ensure the measurement stability of PM2.5 sensors under different temperature environments, current methods primarily focus on selecting components with relatively stable temperature characteristics to reduce the impact of temperature changes. However, this approach places higher performance requirements on the components, leading to a sharp increase in the design and manufacturing costs of PM2.5 sensors. Furthermore, even components with relatively stable temperature characteristics still have limitations. When temperature changes exceed their controllable range, the impact of temperature variations on the components becomes more severe, resulting in significant distortion of the output PM2.5 concentration values. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a high and low temperature compensation method that can ensure the stability and accuracy of PM2.5 sensor measurements under different temperature environments.

[0006] The technical solution adopted by this invention to solve its technical problem is: a PM2.5 sensor high and low temperature compensation method, comprising the following steps:

[0007] S1. Initialization: Configure or reset the various functional modules inside the MCU used;

[0008] S2. Calibration Configuration and Self-Test: Establish communication with the host computer via RS232 serial port, set the calibration configuration in the host computer, select the required calibration channels, and after the settings are completed, the host computer sends the configuration data to the device to be calibrated to perform a self-test, detect whether the channel is connected and provide corresponding indications, and confirm to start the next operation after the operation is completed.

[0009] S3. Room temperature, high temperature and low temperature calibration: After receiving the start command, start room temperature, high temperature and low temperature calibration in the calibration chamber respectively. During the calibration process, check whether Grimm has reached the set sampling point. When it approaches five concentration values, turn off the stirring mechanism and let it stand for two minutes when it reaches the calibration point ±10. Then record the number of particles corresponding to these five calibration points, write the recorded values ​​into the device to be calibrated and save it.

[0010] S4. Compensation function construction: Based on the room temperature calibration results, high temperature calibration results and low temperature calibration results, compensation functions between high temperature and room temperature and between low temperature and room temperature are constructed respectively.

[0011] S5. PM2.5 Concentration Sampling Value Compensation: The temperature value transmitted from the NTC in the product is input into the corresponding compensation function to calculate the PM2.5 concentration compensation value. The PM2.5 concentration sampling value output by the product is added to the PM2.5 concentration compensation value to obtain the compensated PM2.5 concentration sampling value.

[0012] Furthermore, in step S4, the compensation function is the relationship between the temperature value and the PM2.5 concentration compensation value.

[0013] Furthermore, the compensation function represents a linear relationship between the temperature value and the PM2.5 concentration compensation value.

[0014] Furthermore, the compensation function is:

[0015] Δy=kx1+f

[0016] In the formula, Δy represents the PM2.5 concentration compensation value; x1 represents the temperature value; k and f are obtained through fitting.

[0017] Furthermore, the relationship between the particle number and the PM2.5 concentration value in step S3 is as follows:

[0018]

[0019] In the formula, y represents the PM2.5 concentration value; x2 represents the number of particles; and a, b, c, d, and e are obtained through polynomial fitting.

[0020] Furthermore, the various functional modules inside the MCU in step S1 include the MCU operating frequency module, the input / output module of the IO port, the timer, and the detection channel module of the ADC.

[0021] Furthermore, in step S2, the host computer is a computer.

[0022] Furthermore, in step S3, the five concentration values ​​are 500, 300, 150, 60, and 24.

[0023] The beneficial effects of this invention are:

[0024] This invention constructs compensation functions between high temperature and room temperature, and between low temperature and room temperature, based on calibration results at room temperature, high temperature, and low temperature. The temperature value transmitted from the NTC in the product is then substituted into the corresponding compensation functions to calculate the PM2.5 concentration compensation value. Finally, the PM2.5 concentration sampling value output by the product is added to the PM2.5 concentration compensation value to obtain the compensated PM2.5 concentration sampling value. This improves the measurement stability and accuracy of the PM2.5 sensor under different temperature environments, enabling it to adapt to various extreme environments. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Figure 1 This is a flowchart of the present invention;

[0027] Figure 2 This is an internal schematic diagram of the designated warehouse in this invention. Detailed Implementation

[0028] The present invention will now be further described in conjunction with the accompanying drawings and preferred embodiments. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention in a schematic manner, and therefore only show the components relevant to the invention.

[0029] Example 1

[0030] like Figure 1 As shown, a method for high and low temperature compensation of a PM2.5 sensor includes the following steps:

[0031] S1. Initialization: Configure or reset the various functional modules inside the MCU (Microcontroller Unit) used.

[0032] Specifically, each functional module includes an MCU operating frequency module, an I / O port input / output module, a timer, and an ADC (digital-to-analog converter) detection channel module. After each functional module is configured, it enters normal operating mode.

[0033] S2. Calibration Configuration and Self-Test: Establish communication with the host computer via RS232 serial port, set the calibration configuration in the host computer, select the required calibration channels, and after the settings are completed, the host computer sends the configuration data to the device to be calibrated for self-testing, checks whether the channel is connected and provides corresponding indications, and confirms to start the next operation after the operation is completed.

[0034] Specifically, the host computer is a computer; the calibration channel is selectable, only the selected channel is calibrated, and the unselected channel is not processed; if the detection channel is connected, it will prompt to start smoke injection; the self-test result is sent back to the host computer. If the self-test is unsuccessful, the configuration needs to be resent to the device to be calibrated for a retest.

[0035] S3. Room temperature, high temperature and low temperature calibration: After receiving the start command, start room temperature, high temperature and low temperature calibration in the calibration chamber respectively. During the calibration process, cyclically check whether the Grimm (PM2.5 detection standard instrument) has reached the set sampling point. When it approaches five concentration values, turn off the stirring mechanism and let it stand for about two minutes when it reaches about ±10 of the calibration point. Then record the particle count corresponding to these five calibration points, write the recorded values ​​into the device to be calibrated and save it.

[0036] Specifically, there are five concentration values: 500, 300, 150, 60, and 24; five calibration points can be set; the stirring mechanism can be a fan; the calibration values ​​and calibration points need to be recorded and stored in a database, which can be traced and exported in Excel format.

[0037] The dust in the calibration chamber is stirred and allowed to settle by a stirring mechanism, resulting in a uniform distribution. Furthermore, the calibration points can be freely adjusted, thus improving the calibration accuracy of the product.

[0038] S4. Construction of compensation functions: Based on the calibration results at room temperature, high temperature and low temperature, compensation functions between high temperature and room temperature and between low temperature and room temperature are constructed respectively.

[0039] Specifically, the compensation function is:

[0040] Δy=kx1+f

[0041] In the formula, Δy represents the PM2.5 concentration compensation value; x1 represents the temperature value; k and f are both obtained through fitting.

[0042] S5. PM2.5 Concentration Sampling Value Compensation: The temperature value transmitted by the NTC (temperature sensor) in the product is input into the corresponding compensation function to calculate the PM2.5 concentration compensation value (i.e. PM2.5 concentration deviation value). The PM2.5 concentration sampling value output by the product is added to the PM2.5 concentration compensation value to obtain the compensated PM2.5 concentration sampling value.

[0043] The relationship between the particle number and PM2.5 concentration in step S3 is as follows:

[0044]

[0045] In the formula, y represents the PM2.5 concentration value; x2 represents the number of particles; and a, b, c, d, and e are all obtained through polynomial fitting.

[0046] Based on the calibration results at room temperature, high temperature, and low temperature, compensation functions between high temperature and room temperature, and between low temperature and room temperature, were constructed respectively. Then, the temperature value transmitted by the NTC in the product was substituted into the corresponding compensation function to calculate the PM2.5 concentration compensation value. Finally, the PM2.5 concentration sampling value output by the product was added to the PM2.5 concentration compensation value to obtain the compensated PM2.5 concentration sampling value. This improved the measurement stability and accuracy of the PM2.5 sensor under different temperature environments, enabling it to adapt to various extreme environments.

[0047] The following example illustrates how to construct a compensation function between high temperature and room temperature:

[0048] Assume that the PM2.5 concentration at room temperature (26℃) is L1, at high temperature (40℃) it is L2, at high temperature (60℃) it is L3, and at high temperature (85℃) it is L4; calculate or fit the compensation function based on the data (40, L2-L1), (60, L3-L1), and (85, L4-L1).

[0049] Example 2

[0050] like Figure 2 As shown, the calibration chamber contains a calibration motherboard, a protocol conversion device, a Grimm, a stirring mechanism, and a device to be calibrated. The calibration motherboard communicates with the host computer via RS232 and connects to the device to be calibrated via CAN communication. The Grimm connects to the calibration motherboard via the protocol conversion device. The stirring mechanism is electrically connected to the calibration motherboard and its stirring is controlled by the calibration motherboard. The smoke injection mechanism is electrically connected to the calibration motherboard and its smoke injection is controlled by the calibration motherboard.

[0051] Specifically, the MCU is installed on the calibration motherboard; the host computer communicates wirelessly with the mobile device via a wireless router, and the mobile device is a mobile phone or tablet; the protocol conversion device is an Ethernet to CAN device, which sends corresponding commands and reads the Grimm measurement value through the TCP / IP communication protocol, and after protocol conversion, finally converts it into CAN and sends it to the calibration motherboard for processing.

[0052] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for high and low temperature compensation of a PM2.5 sensor, characterized in that, Includes the following steps: S1. Initialization: Configure or reset the various functional modules inside the MCU used; S2. Calibration Configuration and Self-Test: Establish communication with the host computer via RS232 serial port, set the calibration configuration in the host computer, select the required calibration channels, and after the settings are completed, the host computer sends the configuration data to the device to be calibrated to perform a self-test, detect whether the channel is connected and provide corresponding indications, and confirm to start the next operation after the operation is completed. S3. Room temperature, high temperature and low temperature calibration: After receiving the start command, start room temperature, high temperature and low temperature calibration in the calibration chamber respectively. During the calibration process, check whether Grimm has reached the set sampling point. When it approaches five concentration values, turn off the stirring mechanism and let it stand for two minutes when it reaches the calibration point ±10. Then record the number of particles corresponding to these five calibration points, write the recorded values ​​into the device to be calibrated and save it. S4. Compensation function construction: Based on the room temperature calibration results, high temperature calibration results and low temperature calibration results, compensation functions between high temperature and room temperature and between low temperature and room temperature are constructed respectively. S5. PM2.5 Concentration Sampling Value Compensation: The temperature value transmitted from the NTC in the product is input into the corresponding compensation function to calculate the PM2.5 concentration compensation value. The PM2.5 concentration sampling value output by the product is added to the PM2.5 concentration compensation value to obtain the compensated PM2.5 concentration sampling value.

2. The PM2.5 sensor high and low temperature compensation method according to claim 1, characterized in that, In step S4, the compensation function is the relationship between the temperature value and the PM2.5 concentration compensation value.

3. The PM2.5 sensor high and low temperature compensation method according to claim 2, characterized in that, The compensation function represents the linear relationship between temperature and PM2.5 concentration compensation values.

4. The PM2.5 sensor high and low temperature compensation method according to claim 3, characterized in that, The compensation function is: Δy=kx1+f In the formula, Δy represents the PM2.5 concentration compensation value; x1 represents the temperature value; k and f are obtained through fitting.

5. The PM2.5 sensor high and low temperature compensation method according to claim 1, characterized in that, The relationship between the particle number and PM2.5 concentration in step S3 is as follows: In the formula, y represents the PM2.5 concentration value; x2 represents the number of particles; and a, b, c, d, and e are obtained through polynomial fitting.

6. The PM2.5 sensor high and low temperature compensation method according to claim 1, characterized in that, The various functional modules inside the MCU in step S1 include the MCU operating frequency module, the input / output module of the IO port, the timer, and the detection channel module of the ADC.

7. The PM2.5 sensor high and low temperature compensation method according to claim 1, characterized in that, In step S2, the host computer is a computer.

8. The PM2.5 sensor high and low temperature compensation method according to claim 1, characterized in that, In step S3, the five concentration values ​​are 500, 300, 150, 60, and 24.

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