Fault-tolerant control method for acceleration control plan of aero-engine

Abstract

According to the fault-tolerant control method for the acceleration control plan of the aero-engine, in the engine acceleration process of the aero-engine, an acceleration fuel flow target obtained at the current moment j and an acceleration fuel flow at the previous moment j-1 are fused and output according to a control program of the ith acceleration control plan, the total variance of the current moment is obtained through weighted calculation, and then the total variance of each acceleration control plan is used for calculation to obtain a weight; calculating the statistical variance of various planned fuels at the current moment; calculating a new weighted average relative fuel quantity in combination with the posterior probability and the semi-variance until the relative error of the weighted average relative fuel quantities before and after iteration is smaller than a set maximum error; and finally, taking the product of the terminated weighted average relative fuel quantity and the accelerated fuel flow fusion output as the accelerated fuel flow fusion output at the current moment.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft engine control, and in particular to a fault-tolerant control method for an aircraft engine acceleration control plan. Background Art

[0002] Surge is an abnormal working state that must be avoided for the normal operation of aircraft engines. However, in order to complete the acceleration quickly during the acceleration process, it is often necessary to approach the surge boundary of the compressor. This contradiction makes the design of the acceleration control plan particularly strict. In order to prevent acceleration surge caused by uncertain factors such as intake distortion and engine degradation, the designed acceleration control plan often reserves a certain surge margin between the surge boundary to ensure the safety of the acceleration process. In order to further improve the transient performance of advanced engines, reducing the designed surge margin has become a feasible key means, which makes it necessary to strengthen the adaptability of the acceleration control plan to disturbance factors such as sensors, actuators and power extraction. A single acceleration control plan is difficult to avoid abnormal operation or failure of core components caused by a single factor failure. The mixed use of multiple plans has become the main countermeasure to improve fault tolerance.

[0003] The fault-tolerant control methods for the various acceleration control plans currently used are either too simple, with disadvantages such as weak fault tolerance or poor performance retention, or too complex parameter settings and optimization adjustments, with poor adaptability to different engines, and the corresponding calculation methods cannot adapt well to changes in the number of weighted fusion acceleration control plans.

[0004] Therefore, in order to solve the problems of simplicity and versatility of fault-tolerant control methods for various acceleration control plans, a fault-tolerant control method for aircraft engine acceleration control plans with strong application capabilities is needed.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0006] The present invention provides a fault-tolerant control method for an aircraft engine acceleration control plan, which can be adapted to acceleration control plans of different engines and different fusion numbers, avoid acceleration surge caused by significant failure of a single disturbance factor and small-range errors of other disturbance factors, and maintain a certain acceleration performance.

[0007] A fault-tolerant control method for an aircraft engine acceleration control plan includes: S100: During the engine acceleration process of an aircraft engine, i A control program that accelerates the control plan at the current moment j The acceleration fuel flow target obtained ( Wfi ) j , and the previous moment j -1 accelerated fuel flow fusion output ( W f,acc ) j-1 , divide the front and back to get the normalized relative fuel quantity x i,j， ; S200: According to the current time j Calculated i Instantaneous variance of an accelerated control scheme d ti,j and the previous moment j A population variance of -1 d i,j-1 Weighted calculation to get the overall variance at the current moment d i,j , its initial value d i,1 According to the prior knowledge, the overall variance of each accelerated control plan is then used d i,j Calculate the weight oh i,j ; S300: Weighted average relative fuel quantity m j At every moment j The initial value needs to be set as the relative fuel amount x i,j and calculate the statistical variance of multiple planned fuel at the current moment s j ; S400: Based on relative fuel quantity x i,j Relative fuel quantity to weighted average m j Size relationship and the statistical variance of multiple planned fuels at the current moment s j Get the semivariance h i,j , according to the weight oh i,j The posterior probability is calculated with the asymmetric Gaussian distribution function c i,j , and then combined with the posterior probability c i,j and semivariance h i,j Calculate the new weighted average relative fuel quantity m j Repeat step S400 until the weighted average relative fuel quantity before and after the iteration is mj The relative error is less than the set maximum error, and finally the weighted average relative fuel quantity is terminated. m j Fusion output with accelerated fuel flow ( W f,acc ) j-1 The product is used as the current acceleration fuel flow fusion output ( W f,acc ) j .

[0008] In the fault-tolerant control method of the aircraft engine acceleration control plan, in step S200, the weight oh i,j The calculation method is: , , , Where ρ is a set constant, which does not exceed 10 -4 .

[0009] In the fault-tolerant control method of the aircraft engine acceleration control plan, the initial value d i,1 for:

[0010] in( W f,id ) k-1 and( W f,id ) k The model simulation results k -1 and k The real-time optimal fuel at the moment, m is the total number of statistical samples, not less than 3000.

[0011] In the fault-tolerant control method of an aircraft engine acceleration control plan, in step S300, the variance s j The calculation method is: , , , Where n is the total number of accelerated control plans used in weighted fusion, which shall not be less than 2.

[0012] In the fault-tolerant control method of the aircraft engine acceleration control plan, in step S400, h i,j , ci,j And new m j The specific calculation steps are as follows: , , , , , Where β is a set constant, ( m j ) new The new m j , ( m j ) final The final iteration terminates m j .

[0013] In the fault-tolerant control method of the aircraft engine acceleration control plan, in step S400, β takes a value of 0.618.

[0014] Compared with the prior art, the present invention has the following advantages: the present invention has fewer parameters for optimization settings, is easy to use and easy to implement by algorithm, and except for a very small number of parameters that require prior knowledge to determine the initial value, the remaining parameter settings are independent of the specific engine characteristics. It can be generally applied to the weighted fusion needs of no less than two acceleration control plans, without paying attention to the disturbance characteristics of the specific plan. The acceleration process controlled by the disclosed method can still maintain a certain acceleration performance in addition to avoiding surge caused by a single fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0016] In the attached picture: Figure 1 It is a control schematic diagram of a fault-tolerant control method in an aircraft engine acceleration controller provided by an embodiment of the present disclosure; Figure 2It is a flowchart of a fault-tolerant control method for multiple acceleration control plans provided by an embodiment of the present disclosure; Figure 3 is an asymmetric Gaussian distribution function image provided by an embodiment of the present disclosure; Figure 4 It is a box plot of the minimum surge margin statistics of different control methods during the acceleration process under the influence of single factor failure of standard atmosphere at sea level and small-range deviation of other factors provided by an embodiment of the present disclosure; Figure 5 It is a box plot of acceleration time statistics of different control methods during the acceleration process under the influence of single factor failure of sea level standard atmosphere and small-scale deviation of other factors provided by an embodiment of the present disclosure; Figure 6 is the range and simulation points of the flight envelope provided by one embodiment of the present disclosure; Figure 7 It is a box plot of the minimum surge margin statistics of different control methods during acceleration under the influence of single factor failure and small-range deviation of other factors within the flight envelope provided by an embodiment of the present disclosure; Figure 8 It is a box plot of acceleration time statistics of different control methods during the acceleration process under the influence of a single factor failure and a small range deviation of other factors within the flight envelope provided by an embodiment of the present disclosure.

[0017] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0018] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0019] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0020] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0021] like Figure 1 to Figure 8 As shown, the fault-tolerant control method of the aircraft engine acceleration control plan includes the following steps: S100: During the engine acceleration process of an aircraft engine, i A control program that accelerates the control plan at the current moment j The acceleration fuel flow target obtained ( W fi ) j , and the previous moment j -1 accelerated fuel flow fusion output ( W f,acc ) j-1 , divide the front and back to get the normalized relative fuel quantity x i,j， ; S200: According to the current time j Calculated i Instantaneous variance of an accelerated control scheme d ti,j and the previous moment j A population variance of -1 d i,j-1 Weighted calculation to get the overall variance at the current moment d i,j , its initial value d i,1 According to the prior knowledge, the overall variance of each accelerated control plan is then used d i,j Calculate the weight oh i,j ; S300: Weighted average relative fuel quantity m j At every moment j The initial value needs to be set as the relative fuel amount x i,j and calculate the statistical variance of multiple planned fuel at the current moment s j ; S400: Based on relative fuel quantity x i,j Relative fuel quantity to weighted average m j Size relationship and the statistical variance of multiple planned fuels at the current moment s j Get the semivariance hi,j , according to the weight oh i,j The posterior probability is calculated with the asymmetric Gaussian distribution function c i,j , and then combined with the posterior probability c i,j and semivariance h i,j Calculate the new weighted average relative fuel quantity m j Repeat step S400 until the weighted average relative fuel quantity before and after the iteration is m j The relative error is less than the set maximum error, and finally the weighted average relative fuel quantity is terminated. m j Fusion output with accelerated fuel flow ( W f,acc ) j-1 The product is used as the current acceleration fuel flow fusion output ( W f,acc ) j .

[0022] In a preferred embodiment of the fault-tolerant control method of the aircraft engine acceleration control plan, in step S200, the weight oh i,j The calculation method is: , , , Where ρ is a set constant, which does not exceed 10 -4 .

[0023] In a preferred embodiment of the fault-tolerant control method of the aircraft engine acceleration control plan, the initial value d i,1 for:

[0024] in( W f,id ) k-1 and( W f,id ) k The model simulation results k -1 and k The real-time optimal fuel at the moment, m is the total number of statistical samples, not less than 3000.

[0025] In a preferred implementation of the fault-tolerant control method for an aircraft engine acceleration control plan, in step S300, the variance s j The calculation method is: , , , Where n is the total number of accelerated control plans used in weighted fusion, which shall not be less than 2.

[0026] In a preferred implementation of the fault-tolerant control method for an aircraft engine acceleration control plan, in step S400, h i,j , c i,j And new m j The specific calculation steps are as follows: , , , , , Where β is a set constant, ( m j ) new The new m j , ( m j ) final The final iteration terminates m j .

[0027] In a preferred implementation of the fault-tolerant control method for an aircraft engine acceleration control plan, in step S400, β takes a value of 0.618.

[0028] In one embodiment, Figure 1 As shown in the figure, a simple fault-tolerant control method for the acceleration control plan of an aircraft engine is applied to the acceleration controller to output the final acceleration fuel flow of weighted fusion. The specific control program flowchart is shown in Figure 2 As shown, the following steps are included: S100: During the engine acceleration process of an aircraft engine, i A control program that accelerates the control plan at the current moment j The acceleration fuel flow target obtained ( W fi ) j , and the previous moment j -1 accelerated fuel flow fusion output (W f,acc ) j-1 , divide the front and back to get the normalized relative fuel quantity x i,j， ; S200: According to the current time j Calculated i Instantaneous variance of an accelerated control scheme d ti,j and the previous moment j A population variance of -1 d i,j-1 Weighted calculation to get the overall variance at the current moment d i,j , its initial value d i,1 According to the prior knowledge, the overall variance of each accelerated control plan is then used d i,j Calculate the weight oh i,j ; S300: Weighted average relative fuel quantity m j At every moment j The initial value needs to be set as the relative fuel amount x i,j and calculate the statistical variance of multiple planned fuel at the current moment s j ; S400: Based on relative fuel quantity x i,j Relative fuel quantity to weighted average m j Size relationship and the statistical variance of multiple planned fuels at the current moment s j Get the semivariance h i,j , according to the weight oh i,j The posterior probability is calculated with the asymmetric Gaussian distribution function c i,j , and then combined with the posterior probability c i,j and semivariance h i,j Calculate the new weighted average relative fuel quantity m j Repeat step S400 until the weighted average relative fuel quantity before and after the iteration is m j The relative error is less than the set maximum error, and finally the weighted average relative fuel quantity is terminated. mj Fusion output with accelerated fuel flow ( W f,acc ) j-1 The product is used as the current acceleration fuel flow fusion output ( W f,acc ) j .

[0029] The above embodiments constitute a complete technical solution of the present disclosure, wherein the number of acceleration control plans adopted can be any number not less than two. The acceleration process controlled by the method described in the present disclosure can avoid a significant decrease in surge margin caused by a single disturbance factor failure and a small range error of other disturbance factors, thereby avoiding the danger of surge; and can avoid a significant decrease in acceleration performance when a single fault affects the acceleration process.

[0030] In another embodiment, the normalization method of the multiple acceleration control plan fuel flow rates in step S100 is:

[0031] In another embodiment, in step S200, the oh i,j The calculation method is:

[0032]

[0033] Where ρ is a constant, which is set based on experience and is generally small, not exceeding 10 -4 .

[0034] Initial Value d i,1 According to the prior knowledge setting, the average variance between the normalized fuel and the normalized optimal fuel obtained by simulating the model under different fault conditions can be obtained, as shown in the formula:

[0035] in( W f,id ) k-1 and( W f,id ) k The model simulation results k -1 and k The real-time optimal fuel at the moment, m is the total number of statistical samples, generally not less than 3000.

[0036]

[0037] In another embodiment, in step S300, the variance s j The calculation method is:

[0038]

[0039]

[0040] Where n is the total number of plans used in weighted fusion, not less than 2.

[0041] In another embodiment, the image of the asymmetric Gaussian distribution in step S400 is as follows: Figure 3 As shown, h i,j , c i,j And new m j The specific calculation steps are as follows:

[0042]

[0043]

[0044]

[0045]

[0046] Where β is a set constant, and generally a value of 0.618 has a better effect. ( m j ) new The new m j , ( m j ) final The final iteration terminates m j .

[0047] The disturbance factors injected in this example, in addition to the normal error influence of the temperature sensor, also take into account the large-scale fault error of the pressure sensor, the fuel metering error and fault, and the normal range and abnormal range of the engine's own power extraction, as shown in Table 1.

[0048] Table 1

[0049] in, L ex is the power extraction size of the engine, p t2is the total intake pressure of the engine, p t25 is the compressor inlet total pressure, p t31 is the compressor outlet total pressure, T t2 is the total engine intake air temperature.

[0050] This example simulates a specific engine component level model to verify the effectiveness of the proposed simple fault-tolerant control method. p t2 The converted fuel flow plan p t31 The weighted fusion of the converted fuel flow plan and the N-dot plan) is used to prove that this method can be better than the two plans (for p t31 The converted fuel flow plan and N-dot plan) take the minimum value, the median of the three plans and directly use oh i,j The method of weighting the three planned fuels can better prevent compressor surge during the acceleration process to verify the characteristics of the method disclosed in the present invention. The specific process is as follows: According to the provisions of the deviation of disturbance factors and the magnitude of fault impact as described in Table 1, assuming that under the standard atmospheric design conditions at sea level, a large-scale fault deviation of a random single disturbance factor and a small-scale deviation of other factors are injected into a specific engine component-level model, the minimum value (2ASs) of two plans, the median (Median) of three plans, and the direct oh i,j The method of weighting three planned fuel (WA) and the simple fault-tolerant control method (EMAD) described in this disclosure were tested for full acceleration, and 3000 groups of tests were conducted under different disturbance combinations. The so-called full acceleration refers to the acceleration process from the engine slow state to the intermediate state. In this process, the throttle lever is pushed quickly to input the step command of the speed control, which fully reflects the effect of the acceleration control plan at different speeds. The minimum surge margin of each method in each acceleration process was counted. SM min For comparison, Figure 4 As shown, SM id Represents the theoretical surge margin target for the design. Figure 4 It shows that the proposed EMAD method can effectively stay away from the surge boundary under fault conditions, the Median method has reached the surge boundary, and the WA method is also very close to the surge boundary. t acc Distribution box plot Figure 5 As shown in Figure 1, according to the requirements of JSSG-2007B, the full acceleration time is defined as the time to reach 95% of the target thrust change. Figure 5 It shows that the proposed EMAD method can better ensure the stability of acceleration performance than the 2ASs method. In summary, the simple fault-tolerant control method proposed in this disclosure can effectively avoid surge and avoid a significant decrease in acceleration performance at sea level.

[0051] Furthermore, the present disclosure also simulates and verifies four fault-tolerant control methods through large-sample random disturbance simulation within the full flight envelope. The specific process is as follows: According to the provisions of the deviation of disturbance factors and the magnitude of fault influence as described in Table 1, the same single disturbance factor fault error and other disturbance factor small range deviations are randomly injected into the engine model at each full acceleration within the full flight envelope, where the flight envelope is as follows: Figure 6 As shown in Figure 2, 10,000 sets of repeated acceleration processes under different disturbance conditions were performed within the envelope, and the minimum surge margin in each acceleration process was calculated. SM min For comparison, Figure 7 As shown, SM b Indicates the surge boundary. Figure 7 It shows that compared with the Median and WA methods, the proposed EMAD method can ensure that surge does not occur far from the surge boundary under full-envelope fault conditions. The distribution box plot of the full-range acceleration time difference between the proposed EMAD method and the 2ASs method is shown in Figure 2. Figure 8 As shown in the figure, the distribution shows that the proposed EMAD method has a smaller acceleration time in the whole flight envelope than the 2ASs method under disturbance, which means that the EMAD method can also avoid a significant decrease in acceleration time in the whole flight envelope. In general, only the simple fault-tolerant control method proposed in the present disclosure can avoid a significant decrease in acceleration performance while ensuring that the surge boundary is not approached in the whole envelope. It can be seen that this method is not only simple and easy to use, but also has obvious benefits.

[0052] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. A fault-tolerant control method for an aircraft engine acceleration control plan, characterized in that: The steps include: S100: During the engine acceleration process of an aircraft engine, i A control program that accelerates the control plan at the current moment j The acceleration fuel flow target obtained ( W fi ) j , and the previous moment j -1 accelerated fuel flow fusion output ( W f,acc ) j-1 , divide the front and back to get the normalized relative fuel quantity x i,j， ; S200: According to the current time j Calculated i Instantaneous variance of an accelerated control scheme d ti,j and the previous moment j A population variance of -1 d i,j-1 Weighted calculation to get the overall variance at the current moment d i,j , its initial value d i,1 According to the prior knowledge, the overall variance of each accelerated control plan is then used d i,j Calculate the weight ω i,j ; S300: Weighted average relative fuel quantity μ j At every moment j The initial value needs to be set as the relative fuel amount x i,j and calculate the statistical variance of multiple planned fuel at the current moment σ j ; S4 00: According to relative fuel quantity x i,j Relative fuel quantity to weighted average μ j Size relationship and the statistical variance of multiple planned fuels at the current moment σ j Get the semivariance h i,j , according to the weight ω i,j The posterior probability is calculated with the asymmetric Gaussian distribution function γ i,j , and then combined with the posterior probability γ i,j and semivariance h i,j Calculate the new weighted average relative fuel quantity μ j Repeat step S400 until the weighted average relative fuel quantity before and after the iteration is μ j The relative error is less than the set maximum error, and finally the weighted average relative fuel quantity is terminated. μ j Fusion output with accelerated fuel flow ( W f,acc ) j-1 The product is used as the current acceleration fuel flow fusion output ( W f,acc ) j .

2. The fault-tolerant control method for an aircraft engine acceleration control plan according to claim 1, characterized in that: Preferably, in step S200, the weight ω i,j The calculation method is: ， ， ， Where ρ is a set constant, which does not exceed 10 -4 .

3. The fault-tolerant control method for an aircraft engine acceleration control plan according to claim 1, characterized in that: Initial Value d i,1 for: ； in( W f,id ) k-1 and( W f,id ) k The model simulation results k -1 and k The real-time optimal fuel at the moment, m is the total number of statistical samples, not less than 3000.

4. The fault-tolerant control method for an aircraft engine acceleration control plan according to claim 1, characterized in that: In step S300, the variance σ j The calculation method is: ， ， ， Where n is the total number of accelerated control plans used in weighted fusion, which shall not be less than 2.

5. The fault-tolerant control method for an aircraft engine acceleration control plan according to claim 4, characterized in that: In step S400, h i,j , γ i,j And new μ j The specific calculation steps are as follows: ， ， ， ， ， Where β is a set constant, ( μ j ) new The new μ j , ( μ j ) final The final iteration terminates μ j .

6. The fault-tolerant control method for an aircraft engine acceleration control plan according to claim 5, characterized in that: In step S400, β takes the value of 0.618.

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