A high-safety control method for aircraft range extenders

Abstract

A high-safety control method for aircraft range extenders is characterized by two features: 1. Addressing the susceptibility of actuators to saturation in aircraft range extenders, a control plan and anti-saturation controller based on actuator margin and system efficiency are designed. This enables the aircraft range extender to improve the system's actuator margin while maintaining a certain level of efficiency; simultaneously, it ensures closed-loop stability of the system even under actuator saturation conditions. 2. Addressing the complex installation environment and susceptibility to disturbances in aircraft range extenders, an anti-disturbance controller based on a disturbance model is designed, ensuring the system is unaffected by sinusoidal and step disturbances. The aforementioned control method enhances the safety of the aircraft range extender system while maintaining its efficiency.

Description

Technical Field

[0001] This invention relates to the field of aircraft technology, specifically a high-safety control method applicable to aircraft range extenders. Background Technology

[0002] An aircraft range extender is the power generation and electrical system within an aviation hybrid power system, primarily composed of an aircraft piston or turboshaft engine, a generator, and a reduction gearbox. The aircraft piston engine drives the generator to produce electricity, providing power to the aviation hybrid power system and thus increasing the range and flight time of a series hybrid aircraft. The aircraft range extender is directly connected in parallel to the DC bus, therefore its dynamic response significantly impacts the performance and safety of all electrical components on the DC bus. Specifically, unlike automotive range extenders, aviation hybrid systems require faster power response, leading to larger and faster actuator adjustments. This makes actuators prone to saturation, causing closed-loop control steady-state error and even system instability. Furthermore, unlike automotive range extenders, aircraft range extenders have a more compact installation environment, a more complex operating environment, and are subject to more disturbances.

[0003] This patent establishes a high-safety control method for aircraft range extenders with two functions: anti-actuator saturation and anti-disturbance. Through a control plan and anti-saturation controller designed based on actuator margin and system efficiency, the system remains stable even when actuators are saturated. Furthermore, an anti-disturbance controller based on a disturbance model ensures the system is unaffected by specific types of disturbances. This control method improves the safety of the aircraft range extender system while maintaining its efficiency. Summary of the Invention

[0004] This invention discloses a high-safety control method applicable to aircraft range extenders, characterized in that:

[0005] 1. The design process of control plans and anti-saturation controllers based on actuator margins and system efficiency includes the following steps:

[0006] Step 1: Based on the small perturbation linearization method, obtain the first-order 2-input 2-output linear model of the air-to-ground range extender, which has the form of equation (1):

[0007]

[0008] Where, ω e Indicates engine angular velocity, THR indicates throttle opening, i q Indicates the Q-axis current command, N e P indicates engine speed. gen Let A, B, C, and D represent the output power of the power generation system, and let them be matrices in the state-space equations.

[0009] Step 2: Set the throttle opening (THR) and Q-axis current command (i) q Substitute into equation (2) to solve for the actual control quantity sat of the actuator output. THR and sat iq :

[0010]

[0011] Among them, THR max The upper bound of THR, THR min This is the lower bound of THR; similarly, i qmax For i q The upper bound of i qmin For i q The lower bound; and the actual control output of the actuator can be merged into a vector u. s ;

[0012]

[0013] Step 3: By finding the maximum value of equation (5), solve for the control plan that balances system efficiency and actuator margin:

[0014]

[0015] Where, η eng Indicates engine efficiency, η gen These represent generator efficiency, and they are all related to P. gen and N e The function; Q and R are positive semi-definite weight matrices;

[0016] Step 4: Design the K matrix using the pole placement method so that the poles of the characteristic polynomial det(sI-A+BK) have negative real parts;

[0017] Step 5: Establish an anti-saturation controller of the form (6):

[0018]

[0019] Where λ is the state variable of the anti-saturation controller; the definitions of matrices A and B are the same as in equation (1); δ is the actual control quantity u output by the actuator. s The difference between the control quantity u output by the feedforward gain matrix and K; safe It is a reasonably selected state feedback matrix; γ is the output of the anti-saturation controller, which directly acts on the control quantity u.

[0020] 2. The design process of a disturbance rejection controller based on a disturbance model includes the following steps:

[0021] Step 1: In order to make the closed-loop steady-state error of the aircraft range extender system zero, the feedforward gain matrix M is obtained based on equation (7):

[0022] M = [D + (C - DK)(-A + BK)] -1 B] -1 (19)

[0023] Step 2: Based on the Sylvester equation in the form of equation (8), solve for the linear transformation matrix X:

[0024] SX-X(A-BK)=B ε (DK-C) (20)

[0025] Among them, B ε The known information is as follows:

[0026]

[0027] And b ε Generally [0 0 1] T The S matrix is ​​the state matrix of the perturbation model.

[0028] Step 3: Based on X obtained in Step 2, calculate B according to Equation (10). σ :

[0029] B σ =-XB ε (twenty two)

[0030] Step 4: Design K using the pole placement method v A matrix such that the characteristic polynomial det(sI-S+B) σ K v The poles have negative real parts;

[0031] Step 5: K can be obtained through equation (11) x matrix:

[0032] K x =KK v X (23)

[0033] Step 6: Take the B obtained in Step 3 σ K obtained in step 4 v K obtained in step 5 x The disturbance rejection controller takes the following forms:

[0034]

[0035] Where ν is the state variable of the perturbation model, u k This is the control quantity output by the disturbance controller. Attached Figure Description

[0036] Figure 1This is a control system architecture diagram of the present invention applied to an aircraft range extender system.

[0037] Beneficial technical effects

[0038] This invention patent addresses the problems of actuator saturation and control system susceptibility to interference in aircraft range extenders. It proposes a high-safety control method suitable for aircraft range extenders, which prevents the system from generating closed-loop steady-state error or instability when the actuator is saturated, prevents disturbances from affecting the range extender system, and enhances the system's safety while ensuring the efficiency of the aircraft range extender. Detailed Implementation Plan

[0039] Technical solution:

[0040] The specific embodiments of this invention are described below with reference to the accompanying drawings:

[0041] 1. Establishment of a linear model for aircraft range extenders

[0042] Assume the aircraft range extender control system adopts the power-speed dual closed-loop control architecture shown in the figure: power generation closed-loop is achieved by adjusting the engine throttle (THR); and power generation closed-loop is achieved by adjusting the Q-axis current (i). q To achieve a closed-loop rotational speed control, the linear model of the air-to-ground range extender system, excluding the delay element, can be assumed to be a first-order 2-input 2-output system with the following general form:

[0043]

[0044] Where, ω e Indicates engine angular velocity, THR indicates throttle opening, i q Indicates the Q-axis current command, N e P indicates engine speed. gen The output power of the power generation system is represented by A, B, C, and D, which are matrices in the state-space equations. They are obtained by the small disturbance linearization method shown in equation (26). Specifically, by applying control variables THR and i to the steady-state operating point of the controlled object in the open-loop state, respectively... q and state quantity ω e By applying a ±1% perturbation, and by solving the partial derivatives of the state variables with respect to the perturbation and the partial derivatives of the output variables with respect to the perturbation, the Jacobi matrix is ​​formed, thereby obtaining the specific values ​​of matrices A, B, C, and D.

[0045]

[0046] 2. Implementation of anti-actuator saturation function

[0047] For aircraft range extenders, the actuators mainly include a throttle servo and an inverter: the throttle servo adjusts the throttle opening (THR), and the inverter adjusts the Q-axis current (i).q However, the throttle body servo has a limited travel, and the inverter has a limited duty cycle range, therefore THR and i q Both are bounded:

[0048]

[0049] Among them, THR max The upper bound of THR, THR min This is the lower bound of THR; similarly, i qmax For i q The upper bound of i qmin For i q The lower bound; the actual control output of the actuator can be combined into a vector u. s :

[0050]

[0051] When the actuator reaches its upper or lower bound, the actual control input to the aircraft range extender cannot continue to change. This may cause a steady-state error in the controlled variable or even system instability. To ensure that the actuator has a larger margin, a control plan that fully considers the actuator margin needs to be designed. That is, the controlled variable of the aircraft range extender, i.e., the power generation P, at different power levels. gen Reference command N for rotational speed e ;

[0052] Next, the control plan is solved based on equation (30):

[0053]

[0054] Where, η eng Indicates engine efficiency, η gen These represent generator efficiency, and they are all related to P. gen and N e The function; Q and R are semi-positive definite weight matrices; by solving the maximum value of equation (30), a control plan that takes into account both system efficiency and actuator margin is obtained;

[0055] Place the above control plan in Figure 1 The corresponding position in the middle can ensure that when the aircraft range extender is working in the control plan, not only is the system highly efficient, but also that there is sufficient margin for adjustment of the actuator at both the upper and lower limits, preventing the actuator from falling into saturation due to instantaneous large adjustments;

[0056] On the other hand, in extreme cases, the actuator may still saturate, so it is necessary to design an anti-saturation controller to ensure the closed-loop stability of the system under execution saturation.

[0057] The state-space form of the anti-saturation controller is:

[0058]

[0059] Where λ is the state variable of the anti-saturation controller; matrices A and B are defined in the same way as in equation (25); K safe K is the state feedback matrix that is reasonably selected; K is the state feedback matrix of the system design described by pole placement pair equation (25), and the placement principle is that all closed-loop poles are located in (-30,0); δ is the actual control quantity u output by the actuator. s The control quantity u output by the feedforward decoupled controller d The difference; γ is the output of the anti-saturation controller, which directly acts on the control quantity u; placing the anti-saturation controller at Figure 1 The corresponding position in the middle allows the anti-saturation controller to be activated and dominate the poles of the closed-loop system once δ is not 0, thus ensuring that the system remains closed-loop stable.

[0060] 3. Implementation of anti-disturbance function

[0061] For aircraft range extenders, the main sources of disturbance can be divided into two categories: electromagnetic interference caused by changes in high-voltage system power and engine torque step disturbance caused by sudden changes in incoming flow. To counteract the impact of these two types of disturbances on control, a disturbance rejection controller based on a disturbance observer can be designed. The specific implementation scheme is as follows:

[0062] First, solve... Figure 1 The feedforward gain matrix M in the figure:

[0063] M = [D + (C - DK)(-A + BK)] -1 B] -1 (32)

[0064] In solving the Sylvester equation, we need to find the X matrix:

[0065] SX-X(A-BK)=B ε (DK-C) (33)

[0066] Among them, B ε The known information is as follows:

[0067]

[0068] Among them, b ε Generally [0 0 1] T ;

[0069] After obtaining X from equation (33), B can be calculated. σ :

[0070] B σ =-XB ε (35)

[0071] Design K using the pole placement method v A matrix such that the characteristic polynomial det(sI-S+B) σ K v The poles are [-8 -9 -10 -11 -12 -13]. T ;

[0072] Finally, K can be obtained through equation (36). x matrix:

[0073] K x =KK v X (36)

[0074] Ultimately, the disturbance rejection controller takes the following form:

[0075]

[0076] Place the disturbance rejection controller in Figure 1 At the corresponding position, the electromagnetic interference caused by the power change of the high-voltage system and the engine torque step term caused by the sudden change in the incoming flow can be compensated by the control quantity, so that the performance of the aircraft range extender is not affected by the disturbance.

Claims

1. A high-safety control method suitable for aircraft range extenders, characterized in that: The anti-saturation function of the aircraft range extender is achieved through a control plan and anti-saturation controller based on actuator margin and system efficiency; the disturbance rejection function of the aircraft range extender is achieved through a disturbance rejection controller based on a disturbance model. The design process of control plans and anti-saturation controllers based on actuator margins and system efficiency includes the following steps: Step 1: Based on the small perturbation linearization method, obtain the first-order 2-input 2-output linear model of the air-to-ground range extender, which has the form shown in equation (1): Where, ω e Indicates engine angular velocity, THR indicates throttle opening, i q Indicates the Q-axis current command, N e P indicates engine speed. gen Let A, B, C, and D represent the output power of the power generation system, and let them be matrices in the state-space equations. Step 2: Set the throttle opening (THR) and Q-axis current command (i) q Substitute into equation (2) to solve for the actual control quantity sat of the actuator output. THR and sat iq : Among them, THR max The upper bound of THR, THR min This is the lower bound of THR; similarly, i qmax For i q The upper bound of i qmin For i q The lower bound; and the actual control output of the actuator can be merged into a vector u. s ; Step 3: By finding the maximum value of equation (5), solve for the control plan that balances system efficiency and actuator margin: Where, η eng Indicates engine efficiency, η gen These represent generator efficiency, and they are all related to P. gen and N e The function; Q and R are positive semi-definite weight matrices; Step 4: Design the K matrix using the pole placement method so that the poles of the characteristic polynomial det(sI-A+BK) have negative real parts; Step 5: Establish an anti-saturation controller of the form (6): Where λ is the state variable of the anti-saturation controller; matrices A and B are defined as in equation (1); δ is the actual control quantity u output by the actuator. s The difference between the control quantity u output by the feedforward gain matrix and K; safe It is a reasonably selected state feedback matrix; γ is the output of the anti-saturation controller, which directly acts on the control quantity u.

2. The high-safety control method for aircraft range extenders according to claim 1, characterized in that: The design process of a disturbance rejection controller based on a disturbance model includes the following steps: Step 1: In order to make the closed-loop steady-state error of the aircraft range extender system zero, the feedforward gain matrix M is obtained based on equation (7): M=[D+(C-DK)(-A+BK) -1 B] -1 (7) Step 2: Based on the Sylvester equation in the form of equation (8), solve for the linear transformation matrix X: SX-X(A-BK)=B ε (DK-C) (8) Among them, B ε The known information is: And b ε Generally [0 0 1] T The S matrix is ​​the state matrix of the perturbation model. Step 3: Based on X obtained in Step 2, calculate B according to Equation (10). σ : B σ =-XB ε (10) Step 4: Design K using the pole placement method v A matrix such that the characteristic polynomial det(sI-S+B) σ K v The poles have negative real parts; Step 5: K can be obtained through equation (11) x matrix: K x =K-K v X (11) Step 6: Take the B obtained in Step 3 σ K obtained in step 4 v K obtained in step 5 x The disturbance rejection controller takes the following forms: Where ν is the state variable of the perturbation model, u k This is the control quantity output by the disturbance controller.

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