Calculation Method, Device, Equipment and Medium for Trim State of Propeller Power System

Abstract

The present application provides a method, device, equipment and medium for calculating the trim state of a propeller power system. The method according to the present application includes: establishing an aviation electric power system simulation model based on the parameters of the electric power system, where the electric power system includes: a battery pack, a motor, and a propeller; constructing a trim constraint of the electric power system according to the aviation electric power system simulation model; solving the trim constraint of the electric power system by using a decoupling algorithm to realize the solution of the trim state sequence of the battery pack, the motor, and the propeller. The technical solution provided by the present application can realize the solution of the trim state sequence of the propeller, the motor, and the battery, and provide a basis for accurately evaluating the energy conversion efficiency of the aircraft power system.

Description

Technical Field

[0001] This document relates to the technical field of propeller power system trimming, and particularly relates to a method, device, equipment and medium for calculating the trimming state of a propeller power system. Background Art

[0002] An electric vertical takeoff and landing aircraft (eVTOL) is a new type of aircraft. Generally, a battery pack is used to drive a permanent magnet synchronous motor, and then the air propeller is driven to provide the power required for the whole aircraft to fly. According to the flight states of the aircraft such as speed, altitude, and thrust demand, determining the trimming working state of this new type of power system is crucial for analyzing and optimizing the flight performance of the whole aircraft.

[0003] Most of the existing trimming analysis methods ignore the influence of flight speed on the performance of the propeller, and do not consider the performance constraints between the components of the electric power system such as the battery pack, the motor, and the propeller. Instead, they use the propulsion power of the aircraft, that is, the product of thrust and speed, to calculate the trimming state of the battery pack. The obtained results may exceed the working ability range of the motor or the propeller, and it is not conducive to accurately evaluating the energy conversion efficiency of the aircraft power system subsequently, resulting in performance analysis deviation and affecting flight safety. Summary of the Invention

[0004] This application provides a method, device, equipment and medium for calculating the trimming state of a propeller power system. By considering the performance constraints between the components of the electric power system such as the battery pack, the motor, and the propeller, it is possible to more accurately analyze and optimize the flight performance of the whole aircraft, ensure that the obtained results meet the actual working ability range of each component, and improve the accuracy of flight performance analysis and flight safety.

[0005] An embodiment of the present invention provides a method for calculating the trimming state of a propeller power system, which is characterized by including:

[0006] Establish an aviation electric power system simulation model based on the parameters of the electric power system, where the electric power system includes: a battery pack, a motor, and a propeller;

[0007] Construct the trimming constraints of the electric power system according to the aviation electric power system simulation model;

[0008] Solve the trimming constraints of the electric power system using a decoupling algorithm to realize the calculation of the trimming state sequences of the battery pack, the motor, and the propeller.

[0009] A device for calculating the trimming state of a propeller power system is characterized by including:

[0010] A model construction module that establishes an aviation electric power system simulation model based on the parameters of the electric power system, where the electric power system includes: a battery pack, a motor, and a propeller;

[0011] A constraint construction module for constructing a trim constraint of an electric power system according to the aviation electric power system simulation model;

[0012] A trim solution module for solving the trim constraint of the electric power system by using a decoupling algorithm to implement the solution of the trim state sequence of the battery pack, the motor, and the propeller.

[0013] An embodiment of the present invention also provides an electronic device, including:

[0014] A processor; and,

[0015] A memory arranged to store computer-executable instructions, which when executed cause the processor to execute the steps of the propeller power system trim state calculation method as described above.

[0016] An embodiment of the present invention also provides a storage medium for storing computer-executable instructions, which when executed implement the steps of the propeller power system trim state calculation method as described above.

[0017] By adopting the embodiment of the present invention, a dynamic simulation model of an aviation electric power system is established, and it is transformed into an equation constraint system according to the trim characteristics; for the equation constraint trim equation system of the electric power system, a decoupling calculation method is introduced. First, through inputs such as the speed and thrust demand of the aircraft, the trim speed of the propeller is calculated, and then the trim duty cycle of the motor is solved, and finally the trim load current of the battery is solved; during the solution process, a quadratic equation of one variable about the trim state quantity needs to be solved multiple times. The invention determines the valid solution according to the range of the component model parameters of the electric power system and the state constraint characteristics; and the solution process does not require repeated iteration, and the key state quantities of the electric power system trim can be quickly determined. It solves the problems in the existing trim analysis methods that ignore the influence of flight speed on the performance of the propeller and do not consider the performance constraints between components of the electric power system such as the battery pack, the motor, and the propeller, and provides a basis for accurately evaluating the energy conversion efficiency of the aircraft power system. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in one or more embodiments of this specification or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in this specification. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a flowchart of the propeller power system trim state calculation method according to the embodiment of the present invention;

[0020] Figure 2Schematic diagram of the trim state calculation device for the propeller power system according to the embodiment of the present invention;

[0021] Figure 3 Schematic diagram for comparing the trim speed of the propeller in the trim state calculation method of the propeller power system according to the embodiment of the present invention with that of Comparative Example 1;

[0022] Figure 4 Schematic diagram for comparing the absolute value of the trim resistance residual speed of the propeller in the trim state calculation method of the propeller power system according to the embodiment of the present invention with that of Comparative Example 1. Detailed implementation manners

[0023] In order to enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings in one or more embodiments of this specification. Obviously, the described embodiments are only a part of the embodiments of this specification, rather than all the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this document.

[0024] Method embodiments

[0025] According to an embodiment of the present invention, a method for calculating the trim state of a propeller power system is provided. Figure 1 Flowchart of the method for calculating the trim state of the propeller power system according to the embodiment of the present invention; according to Figure 1 As shown, the method for calculating the trim state of the propeller power system according to the embodiment of the present invention specifically includes:

[0026] S1. Establish an aviation electric power system simulation model based on the parameters of the electric power system, where the electric power system includes: a battery pack, a motor, and a propeller;

[0027] The parameters of the electric power system in the embodiment of the present invention include: battery pack parameters, motor parameters, and propeller parameters. The battery pack parameters involved include: battery load current, battery output voltage, battery internal resistance, open-circuit voltage, and the number of series-connected and parallel-connected batteries in the battery pack. The motor parameters involved include: motor current, motor controller duty cycle, motor internal resistance, motor back electromotive force constant, motor speed, motor inductance, and motor torque constant. The propeller parameters involved include: propeller torque coefficient, propeller diameter, and the moment of inertia of the motor-propeller shaft. The propeller in the embodiment of the present invention is an air propeller.

[0028] An aviation electric power system simulation model is established according to the above parameters. Compared with other traditional aircraft using fossil fuels, the difference in the electric aircraft in the embodiment of the present invention is the thrust Provided by the electric power system, the simulation model of the aircraft electric power system is as follows:

[0029] (1);

[0030] Among them, is the battery load current, is the battery output voltage, is the battery internal resistance, is the open-circuit voltage, and are the number of series-connected and parallel-connected batteries in the battery pack respectively, is the motor current, is the duty cycle of the motor controller, is the motor internal resistance, is the motor back electromotive force constant, is the motor speed, is the motor inductance, is the motor torque constant, is the propeller torque coefficient, is the propeller diameter, is the moment of inertia of the motor-propeller shaft.

[0031] S2. Construct the trim constraint of the electric power system according to the aircraft electric power system simulation model;

[0032] When the aircraft is in the trim state, the motor and the battery are at the steady-state operating point. Therefore, the change rates of the motor current and the motor speed are zero. Thus, Equation (1) can be simplified as:

[0033] (2);

[0034] Substitute the expression of the motor current in Equation (2) into the first two equality constraints, then the trim equation of the electric power system can be sorted out as the following equality constraint:

[0035] (3);

[0036] Solve the system of equations of Equation (3) with respect to , and to determine the trim states of the propeller, the motor and the battery.

[0037] S3. Solve the trim constraint of the electric power system using a decoupling algorithm to realize the solution of the trim state sequence of the battery pack, the motor and the propeller.

[0038] The trim constraint of the electric power system, i.e., there are three unknowns in Equation (3), but only two equations, and the equations are non-linear and not easy to solve directly.

[0039] Therefore, the embodiment of the present invention proposes a decoupled solution method for Equation (3). First, the required motor speed is solved through the thrust demand of the aircraft for the propeller to obtain the required motor speed , and then substitute it into Equation (3) to solve and . Specifically as follows:

[0040] The trim thrust of the electric aircraft is provided by the propeller, and the propeller thrust is given by the following formula:

[0041] (4);

[0042] where is the thrust coefficient, are all constant coefficients for fitting the thrust coefficient characteristics, and for the air propeller, , , ; is the propeller advance ratio, is the flight speed of the aircraft. Substitute the trim thrust demand into Equation (4), and the equation about is as follows:

[0043] (5);

[0044] Arrange it into the standard quadratic equation form about the rotational speed :

[0045] (6);

[0046] The above equation is a quadratic equation about the rotational speed , and the two solutions are respectively:

[0047] (7);

[0048] To ensure that the trim speed is positive, the first solution in Equation (7) should be taken:

[0049] (8);

[0050] This is the rotational speed of the propeller that satisfies the trim flight state of the electric aircraft.

[0051] The specific steps for calculating the trim duty cycle of the motor are as follows:

[0052] First, substitute the equilibrium speed obtained by equation (8) into the second fraction of equation (3) to obtain:

[0053] (9);

[0054] This is available Express ; Substituting equation (9) into the first fraction of equation (3), we can get:

[0055] (10);

[0056] Rearrange formula (10) into The quadratic equation of :

[0057] (11);

[0058] The two solutions of the equation are:

[0059] (12);

[0060] Choose the second solution as the trim duty cycle:

[0061] (13);

[0062] The propeller torque is Defined as:

[0063] (14);

[0064] The specific steps to calculate the cell balance load current are as follows:

[0065] Substituting the trim duty cycle obtained from equation (13) into equation (9) yields the trim battery current:

[0066] (15);

[0067] In this way, all state quantities of the electric power system's balancing state are obtained.

[0068] In order to prove the effectiveness of the propeller power system trim state calculation method in the embodiment of the present invention, the embodiment of the present invention is compared with an existing trim method. The embodiment of the present invention considers the electric aviation fixed-wing cruising flight state, and the flight speed is The local atmospheric density is , the air resistance that the electric power system needs to balance is:

[0069] (16);

[0070] in, is the trim lift coefficient, is the reference area, and is a constant coefficient reflecting the aerodynamic drag characteristics of the aircraft, is the total mass of the aircraft, is the acceleration due to gravity. The atmospheric density is related to the flight altitude and is given by the following fitting formula of the standard atmosphere model:

[0071] (17);

[0072] The trim state calculation method of the propeller power system provided in the embodiments of the present invention is compared with the trim method proposed in the comparative method (Barufaldi G. N., Morales M. A. V., da Silva R. G. A. et al. Energy Optimal Climb Performance of Electric Aircraft [A]. AIAA Scitech 2019 Forum [C]. AIAA, 2019, 1 - 19) to prove the effectiveness of the trim state calculation method of the propeller power system provided in the embodiments of the present invention:

[0073] The trim method in the above - mentioned comparative method sets the thrust of the electric aircraft motor - driven propeller as:

[0074] (18);

[0075] where is the comprehensive efficiency of the electric power system, is the maximum power of the electric power system, is the normalized rotational speed of the electric - driven propeller. The trim rotational speed of the electric aircraft is:

[0076] (19);

[0077] where is the maximum rotational speed of the propeller.

[0078] The parameters of the eVTOL aircraft used in the embodiments of the present invention are shown in Table 1:

[0079] Table 1 Parameters of eVTOL Aircraft

[0080]

[0081] A series of combinations of flight conditions within the expected flight range of the selected example electric aircraft (including: speed, altitude, power consumption) are selected. When comparing the two methods, Table 2 shows the comparison of the trimming results between Example 1 and Comparative Example 1. Table 2 shows the propeller trimming speeds of Example 1 and Comparative Example 1 under three speeds (120, 160, 200 km / h), two flight altitudes (2 km, 4 km), and two battery power consumptions (0 Ah, 1.5 Ah).

[0082] Table 2 Comparison of the calculation method provided by the embodiment of the present invention and the trimming results of Comparative Example 1

[0083]

[0084] In addition, Example 1 additionally gives the duty cycle of the motor controller and the battery load current. Figure 3 The comparison of the propeller trimming speeds between the method for calculating the trimming state of the propeller power system provided by the embodiment of the present invention and Comparative Example 1 under different flight states is given. Figure 4 The resistance residuals of the method for calculating the trimming state of the propeller power system disclosed in the embodiment of the present invention and Comparative Example 1 are given, that is, the absolute value of the difference between the total propeller thrust and the aerodynamic resistance.

[0085] According to Figure 3 and Figure 4 It can be seen that the method for calculating the trimming state of the propeller power system provided by the embodiment of the present invention takes into account the influence of the air inflow caused by the flight speed on the propeller performance, and the trimming accuracy is significantly improved. The trimming residuals of the method for calculating the trimming state of the propeller power system provided by the embodiment of the present invention are all below 10 N, while the residuals of the comparative example are all above 20 N, and the maximum can reach more than 900 N; the method of the present invention can additionally reveal the duty cycle of the motor controller and the battery load current under the trimming state, and thus can more accurately evaluate the energy utilization efficiency of the electric power system.

[0086] By adopting the embodiments of the present invention, the following beneficial effects are achieved: By adopting the embodiments of the present invention, a dynamic simulation model of an aviation electric power system is established and transformed into an equation constraint system of equations according to the trimming characteristics; for the equation constraint trimming system of equations of the electric power system, a decoupling calculation method is introduced. First, the trimming speed of the propeller is calculated through inputs such as the speed and thrust demand of the aircraft, and then the trimming duty ratio of the motor is solved, and finally the trimming load current of the battery is solved; during the solving process, a quadratic equation of one variable about the trimming state quantity needs to be solved multiple times. The invention determines the valid solution according to the range of the component model parameters of the electric power system and the state constraint characteristics; and the solving process does not require repeated iteration, and the key state quantities of the trimming of the electric power system can be quickly determined. It solves the problems in the existing trimming analysis methods that ignore the influence of flight speed on the performance of the propeller and do not consider the performance constraints between components of the electric power system such as the battery pack, motor, and propeller, and provides a basis for accurately evaluating the energy conversion efficiency of the aircraft power system.

[0087] Device Embodiment 1

[0088] According to an embodiment of the present invention, there is provided a device for calculating the trimming state of a propeller power system. Figure 2 For the schematic diagram of the device for calculating the trimming state of the propeller power system according to the embodiment of the present invention, according to Figure 2 As shown, the device for calculating the trimming state of the propeller power system according to the embodiment of the present invention specifically includes:

[0089] A model construction module 20, which establishes an aviation electric power system simulation model based on the parameters of the electric power system, and the electric power system includes: a battery pack, a motor, and a propeller;

[0090] A constraint construction module 22, which is used to construct the trimming constraints of the electric power system according to the aviation electric power system simulation model;

[0091] A trimming calculation module 24, which is used to solve the trimming constraints of the electric power system by using a decoupling algorithm to realize the solution of the trimming state sequence of the battery pack, the motor, and the propeller.

[0092] This device embodiment is a device embodiment corresponding to the above method embodiment one by one. For the specific implementation of each module, please refer to the above method embodiment and will not be elaborated here.

[0093] Device Embodiment 2

[0094] According to an embodiment of the present invention, there is provided an electronic device, including:

[0095] A processor; and,

[0096] A memory arranged to store computer-executable instructions, and the computer-executable instructions, when executed, cause the processor to execute the steps of the above method embodiment.

[0097] Third Embodiment of the Device

[0098] According to an embodiment of the present invention, a storage medium is provided for storing computer-executable instructions, and the computer-executable instructions, when executed, implement the steps of the method embodiment as described above.

[0099] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating the trim state of a propeller power system, characterized in that include: Establishing an aviation electric power system simulation model based on the parameters of the electric power system, wherein the electric power system includes: a battery pack, a motor, and a propeller; Constructing the trim constraints of the electric power system according to the aviation electric power system simulation model; The decoupling algorithm is used to solve the trim constraints of the electric power system to achieve the sequence solution of the battery pack, motor and propeller trim states; The aviation electric power system simulation model is obtained by formula 1: Formula 1; in, is the battery load current, is the battery output voltage, is the internal resistance of the battery, is the open circuit voltage, and are the number of batteries connected in series and in parallel in the battery pack, is the motor current, is the motor controller duty cycle, is the internal resistance of the motor, is the motor back electromotive force constant, is the motor speed, is the motor inductance, is the motor torque constant, is the propeller torque coefficient, is the propeller diameter, is the moment of inertia of the motor-propeller shaft, is the atmospheric density, where the motor speed is equal to the propeller speed.

2. The method according to claim 1, characterized in that The use of a decoupling algorithm to solve the trim constraints of the electric power system specifically includes: By calculating the thrust demand of the aircraft on the propeller Solving the motor speed in the trim constraints of the electric power system , and then solve the motor trim duty cycle and battery trim load current.

3. The method according to claim 1, characterized in that The steps for obtaining the trim constraints of the electric power system are as follows: Motor current according to the motor and battery pack balance status and motor speed The rate of change is zero and we get: Formula 2; Then the trim constraints of the electric power system are obtained as follows: Formula 3.

4. The method according to claim 3, characterized in that The thrust requirement of the aircraft for the propeller Obtained by formula 4: Formula 4: in, is the thrust coefficient, are all constant coefficients for fitting thrust coefficient characteristics, and for air propellers, , , ; is the propeller advance ratio, is the flight speed of the aircraft.

5. The method according to claim 4, characterized in that The motor trim duty cycle is obtained by formula 5: Formula 5: in, is the propeller torque; The propeller torque is obtained by formula 6: Formula 6.

6. The method according to claim 5, characterized in that The battery balancing load current is obtained by formula 7: Formula 7.

7. A propeller power system trim state calculation device, characterized in that: include: A model building module, which establishes an aviation electric power system simulation model based on the parameters of the electric power system, wherein the electric power system includes: a battery pack, a motor, and a propeller; A constraint construction module, used for constructing a trim constraint of the electric power system according to the aviation electric power system simulation model; The trim solution module is used to solve the trim constraints of the electric power system using a decoupling algorithm to achieve the trim state sequence solution of the battery pack, motor and propeller; The aviation electric power system simulation model is obtained by formula 1: Formula 1; in, is the battery load current, is the battery output voltage, is the internal resistance of the battery, is the open circuit voltage, and are the number of batteries connected in series and in parallel in the battery pack, is the motor current, is the motor controller duty cycle, is the internal resistance of the motor, is the motor back electromotive force constant, is the motor speed, is the motor inductance, is the motor torque constant, is the propeller torque coefficient, is the propeller diameter, is the moment of inertia of the motor-propeller shaft, is the atmospheric density, where the motor speed is equal to the propeller speed.

8. An electronic device comprising: processor; as well as, A memory arranged to store computer executable instructions, which, when executed, cause the processor to perform the steps of the propeller power system trim state calculation method according to any one of claims 1 to 6.

9. A storage medium for storing computer executable instructions, wherein the computer executable instructions, when executed, implement the steps of the method for calculating the trim state of a propeller power system as described in any one of claims 1 to 6.

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