High-safety control method suitable for aviation range extender

Abstract

A high-safety control method suitable for an aviation range extender is characterized by comprising the following two characteristics: 1, aiming at the characteristic that the aviation range extender is resistant to easy saturation of an actuator, a control plan and an anti-saturation controller based on the allowance of the actuator and the system efficiency are designed, so that the aviation range extender can be effectively controlled under the condition of ensuring certain efficiency; the actuator margin of the system is improved; meanwhile, even under the condition that the actuator is saturated, the closed loop stability of the system can be ensured; and 2, aiming at the characteristics that the aviation range extender is complex in installation environment and is subjected to much disturbance, an anti-disturbance controller based on a disturbance model is designed, and the system can be ensured not to be influenced by sine disturbance and step disturbance. According to the control method, the safety of the aviation range extender system can be improved on the basis of ensuring the efficiency of the aviation range extender system.

Description

Technical Field

[0001] The invention relates to the technical field of aviation vehicles, and in particular to a high-safety control method suitable for an aviation range extender. Background Art

[0002] The aviation range extender is a subsystem of the aviation hybrid power system, which is mainly composed of an aviation piston engine or a turboshaft engine, a generator and a reducer. The aviation piston engine drives the generator to generate electricity, providing electrical energy for the aviation hybrid power system, thereby increasing the range and flight time of the series hybrid aircraft. The aviation range extender is directly connected in parallel to the bus, so its dynamic response seriously affects the performance and safety of all electrical appliances on the DC bus. Specifically, unlike the automotive range extender, the aviation hybrid system requires a faster power response, which will result in a larger adjustment range and faster speed for the actuator, so the actuator is prone to saturation, causing closed-loop control static error or even system instability; unlike the automotive range extender, the aviation range extender has a more compact installation environment and a more complex operating environment, and the system is subject to more disturbances.

[0003] This patent establishes a high-safety control method for aviation range extenders with two functions: anti-actuator saturation and anti-disturbance. Through the control plan and anti-saturation controller designed based on actuator margin and system efficiency, the system is guaranteed to be stable when the actuator is saturated; through the anti-disturbance controller based on the disturbance model, the system is guaranteed not to be affected by specific types of disturbances. The above control method can improve the safety of the aviation range extender system while ensuring the efficiency of the aviation range extender system. Summary of the invention

[0004] The present invention discloses a high-safety control method applicable to an aviation range extender, which is characterized by:

[0005] 1. The design process of the control plan and anti-windup controller based on actuator margin and system efficiency includes the following steps:

[0006] Step 1: Based on the small disturbance linearization method, the first-order 2-input 2-output linear model of the aviation range extender is obtained, and it has the form of formula (1):

[0007]

[0008] Among them, ω e represents the engine angular velocity, THR represents the throttle opening, i q Indicates the Q-axis current command, N e Indicates engine speed, P gen represents the power output of the power generation system, A, B, C, D are matrices in the state space equation;

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

[0010]

[0011] Among them, THR max is the upper bound of THR, THR min is the lower bound of THR; similarly, i qmax for i q The upper bound of i qmin for i q The lower bound of the actuator output can be combined into a vector u s ;

[0012]

[0013] Step 3: By solving the maximum value of equation (5), the control plan that takes into account both system efficiency and actuator margin is solved:

[0014]

[0015] Among them, η eng represents the engine efficiency, η gen represents the generator efficiency, which is related to P gen and N e function; Q and R are semi-positive definite weight matrices;

[0016] Step 4: Design the K matrix by 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-windup controller in the form of equation (6):

[0018]

[0019] Where λ is the state variable of the anti-saturation controller; the definitions of the A and B matrices are the same as in equation (1); δ is the control variable u of the actual output of the actuator s The difference between the control quantity u output by the feedforward gain matrix; K safe 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 the disturbance-resistant controller based on the disturbance model includes the following steps:

[0021] Step 1: In order to make the closed-loop static error of the aviation range extender system 0, the feedforward gain matrix M is solved based on equation (7):

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

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

[0024] SX-X(A-BK)=B ε (DK-C) (20)

[0025] Among them, B ε It is known that:

[0026]

[0027] And b ε Usually [0 0 1] T ; S matrix is ​​the state matrix of the disturbance model;

[0028] Step 3: Based on X obtained in step 2, calculate B based on formula (10) σ :

[0029] B σ =-XB ε (twenty two)

[0030] Step 4: Design K by pole placement v Matrix, so that the characteristic polynomial det(sI-S+B σ K v ) poles have negative real parts;

[0031] Step 5: K can be obtained by formula (11) x matrix:

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

[0033] Step 6: Add the B obtained in step 3 σ , K obtained in step 4 v , K obtained in step 5 x , the form of the anti-disturbance controller is:

[0034]

[0035] Among them, ν is the state quantity of the disturbance model, u k is the control quantity output by the disturbance controller. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0037] Beneficial technical effects

[0038] In response to the problems of easy saturation of the actuator and susceptibility of the control system to interference in aviation range extenders, the patent of this invention proposes a high-safety control method suitable for aviation range extenders to prevent the system from generating closed-loop static error or instability when the actuator is saturated, and to prevent the influence of disturbances on the range extender system. Under the premise of ensuring the efficiency of the aviation range extender, the safety of the system is enhanced. Specific implementation plan

[0039] Technical solution:

[0040] The following is a detailed description of the specific implementation methods of the present invention in conjunction with the accompanying drawings:

[0041] 1. Establishment of the linear model of aviation range extender

[0042] Assume that the control system of the aviation range extender adopts the power-speed dual closed-loop control architecture as shown in the figure: by adjusting the engine throttle THR, the power generation power closed loop is realized; by adjusting the Q-axis current i q , realizing the speed closed loop; then the linear model of the aviation range extender system without delay link can be assumed to be a first-order 2-input 2-output system, and has the following general form:

[0043]

[0044] Among them, ω e represents the engine angular velocity, THR represents the throttle opening, i q Indicates the Q-axis current command, N e Indicates engine speed, P gen represents the power output of the power generation system; A, B, C, and D are matrices in the state space equation, which are obtained by the small disturbance linearization method shown in equation (26); specifically, by giving the control variables THR, i q and the state quantity ω e Apply a disturbance of ±1%, and form the Jacobian matrix by solving the partial derivative of the state quantity with respect to the disturbance quantity and the partial derivative of the output quantity with respect to the disturbance quantity, so as to obtain the specific values ​​of the A, B, C, and D matrices;

[0045]

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

[0047] For the aviation range extender, its actuator mainly includes the throttle servo and inverter: the throttle opening THR is adjusted by the throttle servo, and the Q-axis current i is adjusted by the inverter.q ; However, the throttle servo travel is limited and the inverter duty cycle range is limited, so THR and i q are all bounded:

[0048]

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

[0050]

[0051] When the actuator reaches the upper and lower limits, the actual control quantity input into the aviation range extender cannot continue to change, which may cause static error of the controlled quantity or even system instability. In order to ensure that the actuator has a larger margin, it is necessary to design a control plan that fully considers the actuator margin, that is, the controlled quantity of the aviation range extender at different power levels, that is, the power generation power P gen and the reference command N of the speed e ;

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

[0053]

[0054] Among them, η eng represents the engine efficiency, η gen represents the generator efficiency, which is related to P gen and N e 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 control plan can ensure that when the aviation range extender works on the control plan, not only the system efficiency is high, but also the upper and lower limits of the actuator distance have sufficient margin for adjustment, preventing the actuator from being saturated due to instantaneous large adjustments;

[0056] On the other hand, in extreme cases, the actuator may still fall into saturation, 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-windup controller is:

[0058]

[0059] Where λ is the state variable of the anti-saturation controller; the A and B matrices are defined in the same way as in (25); K safe is a reasonably selected state feedback matrix; K is the state feedback matrix designed for the system described by equation (25) using pole configuration. The configuration principle is that all closed-loop poles are located at (-30, 0); δ is the control quantity u actually output by the actuator s The control quantity u output by the feedforward decoupling controller d The difference between the two; γ is the output of the anti-saturation controller, which directly acts on the control quantity u; the anti-saturation controller is placed at Figure 1 The corresponding position in , once δ is not 0, the anti-saturation controller can be activated and dominate the pole of the closed-loop system, thereby ensuring that the system is still closed-loop stable.

[0060] 3. Implementation of anti-disturbance function

[0061] For aviation range extenders, the main sources of interference can be divided into two categories: electromagnetic interference caused by power changes in the high-voltage system and engine torque step terms caused by sudden changes in incoming flow. In order to offset the impact of these two types of disturbances on control, an anti-disturbance controller based on a disturbance observer can be designed. The specific implementation plan is as follows:

[0062] First solve Figure 1 The feedforward gain matrix M in is:

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

[0064] When solving the Sylvester equation, solve for the X matrix:

[0065] SX-X(A-BK)=B ε (DK-C) (33)

[0066] Among them, B ε It is known that:

[0067]

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

[0069] After solving X according to equation (33), we can calculate B σ :

[0070] B σ =-XB ε (35)

[0071] Design K by pole placement method v Matrix, so 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 by formula (36): x matrix:

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

[0074] Finally, the disturbance rejection controller takes the form:

[0075]

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

Claims

1. A high-safety control method applicable to an aviation range extender, characterized in that: The anti-saturation function of the aviation range extender is realized by a control plan and an anti-saturation controller based on actuator margin and system efficiency; the anti-disturbance function of the aviation range extender is realized by an anti-disturbance controller based on a disturbance model.

2. A high-safety control method suitable for an aviation range extender according to claim 1, characterized in that: The design process of the control plan and anti-windup controller based on actuator margin and system efficiency includes the following steps: Step 1: Based on the small disturbance linearization method, the first-order 2-input 2-output linear model of the aviation range extender is obtained. The model has the form shown in formula (1): Among them, ω e represents the engine angular velocity, THR represents the throttle opening, i q Indicates the Q-axis current command, N e Indicates engine speed, P gen represents the power output of the power generation system, A, B, C, D are matrices in the state space equation; Step 2: Convert the throttle opening THR and Q-axis current command i q Substitute into equation (2) and solve for the actual output control quantity sat of the actuator: THR and sat iq : Among them, THR max is the upper bound of THR, THR min is the lower bound of THR; similarly, i qmax for i q The upper bound of i qmin for i q The lower bound of the actuator output can be combined into a vector u s ; Step 3: By solving the maximum value of equation (5), the control plan that takes into account both system efficiency and actuator margin is solved: Among them, η eng represents the engine efficiency, η gen represents the generator efficiency, which is related to P gen and N e function; Q and R are semi-positive definite weight matrices; Step 4: Design the K matrix by pole placement method so that the poles of the characteristic polynomial det(sI-A+BK) have negative real parts; Step 5: Establish an anti-windup controller in the form of equation (6): Where λ is the state variable of the anti-saturation controller; the definitions of the A and B matrices are the same as in equation (1); δ is the control variable u of the actual output of the actuator s The difference between the control quantity u output by the feedforward gain matrix; K safe is a reasonably selected state feedback matrix; γ is the output of the anti-saturation controller, which directly acts on the control quantity u.

3. A high-safety control method suitable for an aviation range extender according to claim 1, characterized in that: The design process of the disturbance-resistant controller based on the disturbance model includes the following steps: Step 1: In order to make the closed-loop static error of the aviation range extender system 0, the feedforward gain matrix M is solved based on equation (7): M=[D+(C-DK)(-A+BK) -1 B] -1 (7) Step 2: Based on the Sylvester equation shown in equation (8), solve the linear transformation matrix X: SX-X(A-BK)=B ε (DK-C) (8) Among them, B ε It is known that: And b ε Usually [0 0 1] T ; S matrix is ​​the state matrix of the disturbance model; Step 3: Based on X obtained in step 2, calculate B based on formula (10) σ : B σ =-XB ε (10) Step 4: Design K by pole placement v Matrix, so that the characteristic polynomial det(sI-S+B σ K v ) poles have negative real parts; Step 5: K can be obtained by formula (11) x matrix: K x =K-K v X (11) Step 6: Add the B obtained in step 3 σ , K obtained in step 4 v , K obtained in step 5 x , the form of the anti-disturbance controller is: Among them, ν is the state quantity of the disturbance model, u k is the control quantity output by the disturbance controller.

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