EGR system-based post-oxygen closed-loop control method and controller

Abstract

The application discloses a kind of based on EGR system's post-oxygen closed loop control method and controller, comprising: S1: closing EGR system, according to the speed load determines the post-oxygen basic target voltage of EGR system and the inherent deviation of pre-oxygen basic;S2: opening EGR system, according to EGR rate determines the average correction value of post-oxygen target voltage and the average correction value of pre-oxygen inherent deviation;S3: the average correction value of post-oxygen target voltage is corrected to post-oxygen basic target voltage using, obtains post-oxygen target voltage, using pre-oxygen inherent deviation average correction value is corrected to pre-oxygen basic inherent deviation, obtains pre-oxygen inherent deviation;S4: based on the deviation of post-oxygen measured voltage and post-oxygen target voltage PI control obtains post-oxygen closed loop correction;S5: using post-oxygen closed loop correction and pre-oxygen inherent deviation is corrected to pre-oxygen measured air-fuel ratio, obtains pre-oxygen final measured air-fuel ratio, and make pre-oxygen final measured air-fuel ratio participate in pre-oxygen closed loop PID control, control post-oxygen measured voltage in post-oxygen target voltage vicinity.

Description

Post-oxygen closed-loop control method and controller based on EGR system Technical Field

[0001] This invention relates to the field of automotive exhaust purification technology, and more particularly to a closed-loop control method and controller for post-oxygenation based on an EGR system. Background Technology

[0002] With the implementation of the China VI emission standard for light-duty vehicles in 2018, emission and fuel consumption standards for automobiles have become even stricter. To further reduce nitrogen oxide emissions and fuel consumption, the Exhaust Gas Recirculation (EGR) system has been re-applied to engine control systems. However, current closed-loop oxygen control methods with EGR systems do not consider the impact of exhaust gas combustion on the pre-oxygen signal, catalytic converter window, and post-oxygen voltage.

[0003] After the EGR valve opens, the exhaust gas enters the cylinder for combustion, which mainly has two effects:

[0004] 1. Oxygen sensors have different sensitivities to different exhaust components. The sensitivity of an oxygen sensor is actually the diffusion rate of exhaust components. Oxygen sensors are greatly affected by O2, HC, CO, and H2. Because the combustion of exhaust gas changes the composition of the exhaust, the air-fuel ratio measured by the front oxygen sensor for the same oxygen content will differ under the same speed, load, and EGR rate.

[0005] 2. Similarly, the combustion of exhaust gas changes the composition of the exhaust gas, resulting in different target oxygen voltages under optimal original exhaust conditions.

[0006] Due to the shortcomings of the existing technologies mentioned above, two problems arise:

[0007] 1. Existing closed-loop control methods for post-oxygen are unable to stably control the post-oxygen voltage near the target voltage, thus posing difficulties for emission control.

[0008] 2. The post-oxygen closed-loop correction dlatrmo is the core parameter for diagnosing the pre- and post-oxygen offset. Due to the instability of the post-oxygen voltage control, the absolute value of dlatrmo is too large, which can easily lead to false alarms in the diagnosis of pre- and post-oxygen offset. Summary of the Invention

[0009] The purpose of this invention is to provide a post-oxygen closed-loop control method and controller based on an EGR system, so as to solve the problem that existing post-oxygen closed-loop control methods cannot stably control the post-oxygen voltage near the target voltage.

[0010] To solve the above technical problems, the present invention provides a post-oxygen closed-loop control method based on an EGR system, comprising:

[0011] S1: Turn off the EGR system and determine the basic target voltage U of the EGR system after oxygen based on the engine speed and load. set,i and the inherent deviation λ of pre-oxygen inter,i ;

[0012] S2: Activate the EGR system and determine the average correction value of the post-oxygen target voltage based on the EGR rate. set,cor Average correction value of inherent deviation of pre-oxygen inter,cor ;

[0013] S3: Utilizing the average correction value of the post-oxygen target voltage set,cor Post-oxygen basic target voltage U set,i After correction, the target voltage U of post-oxygen is obtained. set Using the average correction value of the inherent bias of the pre-oxygen inter,cor The fundamental inherent bias λ of pre-oxygen inter,i After correction, the inherent deviation λ of the pre-oxygen is obtained. inter ;

[0014] S4: Based on the measured post-oxygenation voltage U mea and post-oxygen target voltage U set The deviation is controlled by PI to obtain the post-oxygen closed-loop correction dlatrmo.

[0015] S5: Correcting dlatrmo and the inherent bias λ of pre-oxygen using post-oxygen closed-loop correction. inter Measured air-fuel ratio λ before oxygen production LSU After correction, the final measured air-fuel ratio λ before oxygen production is obtained. act And make the final measured air-fuel ratio λ before oxygenation act Involved in the pre-oxygen closed-loop PID control, the measured post-oxygen voltage U mea Controlled at the post-oxygen target voltage U set nearby.

[0016] Furthermore, the post-oxygen target voltage U set,i and the inherent deviation λ of pre-oxygen inter,i The specific methods for determining this include:

[0017] S11: During the drum test, shut off the EGR system and run the engine at the set speed and load.

[0018] S12: Adjust the inherent deviation of the front oxygen under the current working condition, so that the rear oxygen voltage is stabilized at different voltage values ​​around 0.68V, and measure the original discharge results at different voltage values;

[0019] S13: Select the first post-oxygenation voltage corresponding to the best original displacement result as the basic target voltage U for post-oxygenation.set,i The first pre-oxygen inherent bias corresponding to the best original displacement result is taken as the pre-oxygen basic inherent bias λ. inter,i .

[0020] Furthermore, the average correction value of the post-oxygen basic target voltage. set,cor Average correction value of inherent deviation of pre-oxygen inter,cor The methods for determining this include:

[0021] S21: During the drum test, the EGR system is activated to run the engine at the set EGR rate and set speed load;

[0022] S22: Adjust the inherent deviation of the front oxygen under the current operating conditions to stabilize the rear oxygen voltage at different voltage values ​​around 0.68V, and measure the original discharge results at different voltage values;

[0023] S23: Select the second post-oxygen voltage and the inherent deviation of the second pre-oxygen voltage corresponding to the best original arrangement result, and then subtract the post-oxygen basic target voltage U from the second post-oxygen voltage. set,i Obtain the post-oxygen target voltage correction value By subtracting the fundamental intrinsic bias λ of pre-oxygen from the second pre-oxygen intrinsic bias inter,i The correction value λ for the inherent bias of the pre-oxygen was obtained. inter,cor ;

[0024] S24: Correction value for post-oxygen target voltage at different speeds and loads under the same EGR rate. Correction value λ for inherent deviation of pre-oxygen inter,cor The average value of the target oxygen voltage at this EGR rate is obtained by taking the average of the two values. set,cor Average correction value of inherent deviation of pre-oxygen inter,cor .

[0025] Furthermore, the post-oxygen target voltage U set The calculation formula is:

[0026] set,cor (1)

[0027] Pre-oxygen inherent bias λ inte The calculation formula is:

[0028] inter,cor (2).

[0029] Furthermore, step S4 specifically includes:

[0030] S41: Adjust the post-oxygen target voltage U set and measured voltage Umea Converted to post-oxygen target air-fuel ratio λ respectively set and measured air-fuel ratio λ mea And based on the target air-fuel ratio λ after oxygen set and measured air-fuel ratio λ mea Calculated oxygen-air-fuel ratio deviation λ delta ;

[0031] S42: Based on the post-oxygen air-fuel ratio deviation λ delta Under the P and I terms of post-oxygen closed-loop control, respectively, calculate the P term output dlahp and I term output dlahi of the post-oxygen closed-loop control.

[0032] S43: Based on the post-oxygen air-fuel ratio deviation λ delta The P-term output dlahp and the I-term output dlahi are used to calculate the post-oxygen closed-loop correction dlatrmo.

[0033] Furthermore, the post-oxygen air-fuel ratio deviation λ delta The calculation formula is:

[0034] (3)

[0035] Where, m ex This refers to the exhaust flow rate.

[0036] Furthermore, the formula for calculating the P-term output dlahp of the post-oxygen closed-loop control is as follows:

[0037] (4)

[0038] in, This is the adjustment coefficient for term P. This is a correction for the P term based on exhaust flow rate;

[0039] (5)

[0040] in, This is the adjustment coefficient for term I. This is a correction for term I based on exhaust flow rate.

[0041] Furthermore, the formula for calculating the post-oxygen closed-loop corrected dlatrmo is as follows:

[0042] (6).

[0043] Furthermore, the final measured air-fuel ratio λ before oxygen production... act The calculation formula is:

[0044] (7).

[0045] In addition, the present invention also discloses a controller, which includes a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, it can implement the above-mentioned oxygen closed-loop control method.

[0046] The beneficial effects of this invention are as follows: By calculating the average correction value of the target voltage after oxygen and the average correction value of the inherent deviation of oxygen before oxygen based on the current EGR rate; then, by correcting the target voltage after oxygen with the average correction value of the target voltage after oxygen, the influence of exhaust gas combustion on the target voltage after oxygen under optimal original emission conditions can be eliminated, ensuring that the target voltage after oxygen selected under different EGR rates under various operating conditions can achieve optimal emissions; by correcting the inherent deviation of oxygen before oxygen with the average correction value of the inherent deviation of oxygen before oxygen, the influence of exhaust component changes caused by exhaust gas combustion on the air-fuel ratio measured by oxygen before oxygen can be eliminated, ensuring that the air-fuel ratio signal measured by oxygen before oxygen is true under different EGR rates under various operating conditions; finally, by controlling the target voltage of oxygen before oxygen through closed-loop control, the purpose of optimizing emissions can be achieved, effectively reducing the emissions of CO, NOx and particulate pollutants. Attached Figure Description

[0047] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, use the same reference numerals to denote the same or similar parts. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0048] Figure 1 is a flowchart of the closed-loop control method for post-oxygen with EGR system;

[0049] Figure 2 is a schematic diagram of the closed-loop control principle of the post-oxygen system with EGR.

[0050] Figure 3 shows the post-oxygen voltage performance of a certain EGR project after the introduction of this method. Detailed Implementation

[0051] Figure 1 illustrates a post-oxygen closed-loop control method based on an EGR system, comprising:

[0052] S1: Turn off the EGR system and determine the basic target voltage U of the EGR system after oxygen based on the engine speed and load. set,i and the inherent deviation λ of pre-oxygen inter,i ;

[0053] S2: Activate the EGR system and determine the average correction value of the target oxygen voltage based on the EGR rate (i.e., the ratio of the recirculated exhaust gas volume to the total intake air volume in the intake cylinder). set,cor Average correction value of inherent deviation of pre-oxygen inter,cor ;

[0054] S3: Utilizing the average correction value of the post-oxygen target voltage set,cor Post-oxygen basic target voltage U set,i After correction, the target voltage U of post-oxygen is obtained. set Using the average correction value of the inherent bias of the pre-oxygen inter,cor The fundamental inherent bias λ of pre-oxygen inter,i After correction, the inherent deviation λ of the pre-oxygen is obtained. inter ;

[0055] S4: Based on the measured post-oxygenation voltage U mea and post-oxygen target voltage U set The deviation is controlled by PI to obtain the post-oxygen closed-loop correction dlatrmo;

[0056] S5: Correcting dlatrmo and the inherent bias λ of pre-oxygen using post-oxygen closed-loop correction. inter Measured air-fuel ratio λ before oxygen production LSU After correction, the final measured air-fuel ratio λ before oxygen supply is obtained. act And make the final measured air-fuel ratio λ before oxygenation act Involved in the pre-oxygen closed-loop PID control, the measured post-oxygen voltage U mea Controlled at the post-oxygen target voltage U set nearby.

[0057] This application calculates the post-oxygen target average voltage correction value based on the current EGR rate. set,cor Average correction value of inherent deviation of pre-oxygen inter,cor Correction value of target average voltage after oxygen set,cor Average correction value of inherent deviation of pre-oxygen inter,cor The basic target voltage U after oxygenation was tested respectively. set,i and the inherent deviation λ of pre-oxygen inte By making corrections, we can ensure that we obtain the most accurate measured air-fuel ratio signal before oxygen and the target voltage after oxygen under optimal emission conditions. Furthermore, by controlling the after oxygen voltage near the target voltage through a closed-loop after oxygen system, we can optimize emissions and effectively reduce emissions of CO, NOx, and particulate pollutants.

[0058] According to one embodiment of this application, the post-oxygen basic target voltage U set,i and the inherent deviation λ of pre-oxygen inter,i The specific methods for determining this include

[0059] S11: During the drum test, shut off the EGR system and run the engine at the set speed and load.

[0060] S12: Adjust the inherent deviation of the front oxygen under the current working condition, so that the rear oxygen voltage is stabilized at different voltage values ​​around 0.68V, and measure the original discharge results at different voltage values;

[0061] S13: Select the first post-oxygenation voltage corresponding to the best original displacement result as the basic target voltage U for post-oxygenation. set,i The first pre-oxygen inherent bias corresponding to the best original displacement result is taken as the pre-oxygen basic inherent bias λ. inter,i ;

[0062] For other speed load points, the post-oxygen basic target voltage and pre-oxygen basic inherent deviation are calibrated using the same method described in steps S11-S13 above.

[0063] Drum tests show that with the current oxygen closed-loop control, the results of the primary exhaust vary significantly under different post-oxygen voltages, and the best results are obtained only when the post-oxygen voltage is controlled around 0.68V. In actual control, the post-oxygen voltage (i.e., the target post-oxygen voltage) under the optimal primary exhaust at different speed loads varies. Therefore, this invention, when measuring the pre-arrangement results, operates the engine at a set speed load while stabilizing the post-oxygen voltage around 0.68V.

[0064] Furthermore, the characteristic curve of the front oxygen sensor (the air-fuel ratio corresponding to the pump current) is calibrated based on a standard air-fuel mixture. Different engines have different air-fuel mixture compositions compared to the standard mixture; the air-fuel mixture composition also varies under different operating conditions for the same engine. This results in the front oxygen sensor measuring different air-fuel ratios for the same oxygen content when applied to different engines or the same engine under different operating conditions. The system assumes that when the rear oxygen voltage is at the target voltage, the theoretical front oxygen air-fuel ratio should be 1. The deviation between the actual and theoretical air-fuel ratio at this point is defined as the inherent deviation of the front oxygen sensor under the current operating condition.

[0065] According to one embodiment of this application, the average correction value of the post-oxygen target voltage. set,cor Average correction value of inherent deviation of pre-oxygen inter,cor The methods for determining this include:

[0066] S21: During the drum test, the EGR system is activated to run the engine at the set EGR rate and set speed load;

[0067] S22: Adjust the inherent deviation of the front oxygen under the current operating conditions to stabilize the rear oxygen voltage at different voltage values ​​around 0.68V, and measure the original discharge results at different voltage values;

[0068] S23: Select the second post-oxygen voltage and the inherent deviation of the second pre-oxygen voltage corresponding to the best original arrangement result, and then subtract the post-oxygen basic target voltage U from the second post-oxygen voltage. set,i Obtain the post-oxygen target voltage correction value By subtracting the fundamental pre-oxygen bias λ from the second pre-oxygen inherent bias inter,i The correction value λ for the inherent bias of the pre-oxygen was obtained. inter,cor ;

[0069] S24: Correction value for post-oxygen target voltage at different speeds and loads under the same EGR rate. Correction value λ for inherent deviation of pre-oxygen inter,cor The average value of the target oxygen voltage at this EGR rate is obtained by taking the average values ​​of the two values. set,cor Average correction value of inherent deviation of pre-oxygen inter,cor .

[0070] After completing steps S1 and S2 above, when the engine operates at a certain speed, load, and EGR rate, the basic target voltage U of the post-oxygen system, determined by the above steps, will be directly used according to the linear difference. set,i Average correction value of post-oxygen target voltage set,cor and the inherent deviation λ of pre-oxygen inter,i Average correction value of inherent deviation of pre-oxygen inter,cor .

[0071] According to one embodiment of this application, the post-oxygen target voltage U set The calculation formula is:

[0072] set,cor (1)

[0073] Average correction value of post-oxygen target voltage set,co The correction can eliminate the influence of exhaust gas combustion on the target voltage of post-oxygen under the optimal original emission, ensuring that the target voltage of post-oxygen selected under different EGR rates under various operating conditions can achieve the optimal emission.

[0074] Pre-oxygen inherent bias λ inte The calculation formula is:

[0075] inter,cor (2)

[0076] Average correction value based on pre-oxygen inherent deviation inter,corThe correction eliminates the influence of exhaust gas composition changes caused by exhaust gas combustion on the actual measured air-fuel ratio of the pre-oxygen, ensuring the accuracy of the air-fuel ratio signal measured at different EGR rates under various operating conditions.

[0077] According to one embodiment of this application, step S4 specifically includes:

[0078] S41: Adjust the post-oxygen target voltage U set and measured voltage U mea The target air-fuel ratio λ is obtained by converting the voltage and air-fuel ratio using characteristic conversion (there is a one-to-one correspondence between voltage and air-fuel ratio). set and measured air-fuel ratio λ mea And based on the target air-fuel ratio λ after oxygen set and measured air-fuel ratio λ mea Calculated oxygen-air-fuel ratio deviation λ delta ;

[0079] S42: Based on the post-oxygen air-fuel ratio deviation λ delta Under the P and I terms of post-oxygen closed-loop control, respectively, calculate the P term output dlahp and I term output dlahi of the post-oxygen closed-loop control.

[0080] S43: Based on the post-oxygen air-fuel ratio deviation λ delta The P-term output dlahp and the I-term output dlahi are used to calculate the post-oxygen closed-loop correction dlatrmo.

[0081] According to one embodiment of this application, the post-oxygen air-fuel ratio deviation λ delta The calculation formula is:

[0082] (3)

[0083] Where, m ex This refers to the exhaust flow rate.

[0084] According to one embodiment of this application, the formula for calculating the P-term output dlahp of the post-oxygen closed-loop control is as follows:

[0085] (4)

[0086] in, This is the adjustment coefficient for term P. This is a correction for the P term based on exhaust flow rate;

[0087] (5)

[0088] in, This is the adjustment coefficient for term I. This is a correction for term I based on exhaust flow rate.

[0089] According to one embodiment of this application, the formula for calculating the post-oxygen closed-loop modified dlatrmo is as follows:

[0090] (6).

[0091] According to one embodiment of this application, the final measured air-fuel ratio λ before oxygenation... act The calculation formula is:

[0092] (7).

[0093] The post-oxygen closed-loop control principle is shown in Figure 2. The post-oxygen closed-loop control conditions must be met: both the post-oxygen closed-loop P condition and the post-oxygen closed-loop I condition must be met simultaneously.

[0094] 1. The following conditions must be met simultaneously for the post-oxygen closed-loop P condition:

[0095] A. Start-up successful and no catalytic converter damage or misfire.

[0096] B. Pre-oxygen closed-loop and reliable pre-oxygen supply.

[0097] C. The target air-fuel ratio is 1 and the exhaust flow integral reaches the threshold.

[0098] D. Catalyst temperature is within a certain range

[0099] 2. The following conditions must be met simultaneously for post-oxygen closed-loop condition I.

[0100] A. Load change rate is within a certain range

[0101] B. Desorption flow rate diagnosis was not performed.

[0102] C. Speed ​​load is within a certain range

[0103] D. The target air-fuel ratio is 1 and the exhaust flow integral reaches the threshold.

[0104] E. Catalyst temperature is within a certain range

[0105] Furthermore, this invention also discloses a controller, which includes a memory and a processor. The memory stores a computer program, and when the computer program is executed by the processor, it can implement the aforementioned post-oxygen closed-loop control method. This controller can be mounted on a range extender to perform post-oxygen closed-loop control of the EGR system.

[0106] Verification has shown that existing EGR systems using the post-oxygen closed-loop control method of this scheme can effectively control the post-oxygen voltage to stabilize near the target voltage (as shown in Figure 3), and can effectively reduce the emissions of CO, NOx and particulate pollutants (as shown in Table 1).

[0107] Table 1. Emissions performance before and after the introduction of the EGR system in this scheme.

[0108]

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A closed-loop control method for post-oxygenation based on an EGR system, characterized in that, include: S1: Turn off the EGR system and determine the basic target voltage U of the EGR system after oxygen based on the engine speed and load. set,i and the inherent deviation λ of pre-oxygen inter,i S2: Turn on the EGR system and determine the average correction value of the target oxygen voltage based on the EGR rate. set,cor Average correction value of inherent deviation of pre-oxygen inter,cor S3: Utilize the average correction value of the post-oxygen target voltage set,cor Post-oxygen basic target voltage U set,i After correction, the target voltage U of post-oxygen is obtained. set Using the average correction value of the pre-oxygen inherent deviation inter,cor The fundamental inherent bias λ of pre-oxygen inter,i After correction, the inherent deviation λ of the pre-oxygen is obtained. inter S4: Based on the measured post-oxygen voltage U mea and the post-oxygen target voltage U set S5: Using the deviation to obtain the post-oxygen closed-loop correction dlatrmo through PI control; S6: Using the post-oxygen closed-loop correction dlatrmo and the pre-oxygen inherent deviation λ inter Measured air-fuel ratio λ before oxygen production LSU After correction, the final measured air-fuel ratio λ before oxygen supply is obtained. act And make the final measured air-fuel ratio λ of the pre-oxygen act Involved in the pre-oxygen closed-loop PID control, the measured post-oxygen voltage U mea Controlled at the post-oxygen target voltage U set nearby.

2. The post-oxygen closed-loop control method based on an EGR system according to claim 1, characterized in that, The post-oxygenation basic target voltage U set,i and the inherent deviation λ of pre-oxygen inter,i The specific determination method includes: S11: During the drum test, the EGR system is turned off, and the engine is run at a set speed and load; S12: The inherent deviation of the front oxygen voltage under the current operating conditions is adjusted to stabilize the rear oxygen voltage at different voltage values ​​around 0.68V, and the original exhaust results at different voltage values ​​are measured; S13: The first rear oxygen voltage corresponding to the best original exhaust result is selected as the basic target voltage U for the rear oxygen voltage. set,i The first pre-oxygen inherent bias corresponding to the best original displacement result is taken as the pre-oxygen basic inherent bias λ. inter,i .

3. The post-oxygen closed-loop control method based on an EGR system according to claim 2, characterized in that, The average correction value of the post-oxygen target voltage set,cor Average correction value of inherent deviation of pre-oxygen inter,cor The determination method includes: S21: During the drum test, the EGR system is turned on, and the engine is operated at a set EGR rate and a set speed load; S22: The inherent deviation of the front oxygen under the current operating conditions is adjusted to stabilize the rear oxygen voltage at different voltage values ​​around 0.68V, and the original exhaust results at different voltage values ​​are measured; S23: The second rear oxygen voltage and the second inherent deviation of the front oxygen corresponding to the best original exhaust result are selected, and then the basic target voltage U of the rear oxygen is subtracted from the second rear oxygen voltage. set,i Obtain the post-oxygen target voltage correction value The second pre-oxygen inherent bias is obtained by subtracting the pre-oxygen fundamental inherent bias λ. inter,i The pre-oxygen inherent deviation correction value λ is obtained. inter,cor S24: Correction value of the post-oxygen target voltage for different speed loads at the same EGR rate. Correction value λ for inherent deviation of pre-oxygen inter,cor The average value of the target oxygen voltage at this EGR rate is obtained by taking the average values ​​of the two values. set,cor Average correction value of inherent deviation of pre-oxygen inter,cor 。 4. The post-oxygen closed-loop control method based on an EGR system according to claim 3, characterized in that, The post-oxygen target voltage U set The calculation formula is: set,cor (1) The inherent deviation λ of the pre-oxygen inte The calculation formula is: inter,cor （2）。 5. The post-oxygen closed-loop control method based on an EGR system according to claim 4, characterized in that, Step S4 specifically includes: S41: setting the post-oxygen target voltage U... set and measured voltage U mea Converted to post-oxygen target air-fuel ratio λ respectively set and measured air-fuel ratio λ mea And according to the target air-fuel ratio λ after oxygenation set and measured air-fuel ratio λ mea Calculated oxygen-air-fuel ratio deviation λ delta S42: Based on the aforementioned post-oxygen air-fuel ratio deviation λ delta Under the P and I term control conditions of the post-oxygen closed-loop system, respectively, calculate the P term output dlahp and the I term output dlahi of the post-oxygen closed-loop control; S43: Based on the post-oxygen air-fuel ratio deviation λ delta The P-term output dlahp and the I-term output dlahi are used to calculate the post-oxygen closed-loop correction dlatrmo.

6. The post-oxygen closed-loop control method based on an EGR system according to claim 5, characterized in that, The post-oxygen air-fuel ratio deviation λ delta The calculation formula is: (3) Where, m ex This refers to the exhaust flow rate.

7. The post-oxygen closed-loop control method based on an EGR system according to claim 6, characterized in that, The formula for calculating the output dlahp of the P-term in the post-oxygen closed-loop control is as follows: (4) Among them, This is the adjustment coefficient for term P. This is a correction for the P term based on exhaust flow rate; (5) Among them, This is the adjustment coefficient for term I. This is a correction for term I based on exhaust flow rate.

8. The post-oxygen closed-loop control method based on an EGR system according to claim 7, characterized in that, The formula for calculating the post-oxygen closed-loop corrected dlatrmo is as follows: （6）。 9. The post-oxygen closed-loop control method based on an EGR system according to claim 8, characterized in that, The final measured air-fuel ratio λ before oxygenation act The calculation formula is: （7）。 10. A controller, characterized in that, The controller includes a memory and a processor. The memory stores a computer program, which, when executed by the processor, can implement the post-oxygen closed-loop control method according to any one of claims 1-8.

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