Propeller power system balancing state calculation method, device, equipment and medium

Abstract

The invention provides a propeller power system trim state calculation method, device and equipment and a medium, and the method comprises the steps that an aviation electric power system simulation model is established based on parameters of an electric power system, and the electric power system comprises a battery pack, a motor and a propeller; according to the aviation electric power system simulation model, the balancing constraint of the electric power system is constructed; and the balancing constraint of the electric power system is solved through a decoupling algorithm, and balancing state sequence calculation of a battery pack, a motor and a propeller is achieved. According to the technical scheme provided by the invention, the balancing state sequence calculation of the propeller, the motor and the battery can be realized, and a basis is provided for accurately evaluating the energy conversion efficiency of an aircraft power system.

Description

Technical Field

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

[0002] Electric vertical take-off and landing aircraft (eVTOL) is a new type of aircraft that generally uses a battery pack to drive a permanent magnet synchronous motor, which in turn drives an air propeller to provide the aircraft with the power required for flight. Determining the trim working state of this new power system based on the aircraft's flight conditions such as speed, altitude, and thrust requirements is crucial for analyzing and optimizing the flight performance of the entire aircraft.

[0003] Most existing balancing analysis methods ignore the impact of flight speed on propeller performance, and do not consider the performance constraints between electric power system components such as battery packs, motors, and propellers. Instead, they use the aircraft's propulsion power, that is, the product of thrust and speed, to solve the balancing state of the battery pack. The result may exceed the working capacity of the motor or propeller, and is not conducive to the subsequent accurate evaluation of the energy conversion efficiency of the aircraft power system, resulting in performance analysis deviations and affecting flight safety. Summary of the invention

[0004] The present application provides a method, device, equipment and medium for calculating the trim state of a propeller power system. By considering the performance constraints among electric power system components such as battery packs, motors, propellers, etc., it is possible to more accurately analyze and optimize the flight performance of the entire aircraft, ensure that the results obtained are in line with the actual working capacity 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 trim state of a propeller power system, which is characterized by comprising: 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 solution of the battery pack, motor and propeller trim state sequence.

[0006] A propeller power system trim state calculation device, characterized in that it comprises: 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 a sequence solution of the trim states of the battery pack, motor and propeller.

[0007] An embodiment of the present invention further provides an electronic device, including: processor; and, 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 as described above.

[0008] An embodiment of the present invention further provides a storage medium for storing computer executable instructions, wherein the computer executable instructions, when executed, implement the steps of the above-mentioned method for calculating the trim state of a propeller power system.

[0009] By adopting the embodiment of the present invention, a dynamic simulation model of the aviation electric power system is established, and it is converted into a set of equations with equal constraints according to the trimming characteristics; a decoupling calculation method is introduced for the set of equations with equal constraints on the electric power system, firstly, 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 cycle of the motor is solved, and finally the trimming load current of the battery is solved; in the solution process, it is necessary to solve the quadratic equations about the trimming state quantity multiple times, and the invention determines the effective solution according to the range of the model parameters of the electric power system components and the state constraint characteristics; and the solution process does not need to be iterated repeatedly, and the key state quantity of the trimming of the electric power system can be quickly determined. It solves the problem that the existing trimming analysis method ignores the influence of the flight speed on the propeller performance, and does not consider the performance constraints between the electric power system components 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate one or more embodiments of this specification or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0011] Figure 1 It is a flow chart of a method for calculating the trim state of a propeller power system according to an embodiment of the present invention; Figure 2 It is a schematic diagram of a propeller power system trim state calculation device according to an embodiment of the present invention; Figure 3 It is a schematic diagram comparing the propeller trim state calculation method of the propeller power system in the embodiment of the present invention and the propeller trim speed in comparative example 1; Figure 4 It is a schematic diagram comparing the propeller trim resistance residual absolute value speed in the propeller power system trim state calculation method in the embodiment of the present invention and the propeller trim resistance residual absolute value speed in comparative example 1. DETAILED DESCRIPTION

[0012] In order to enable those skilled in the art to better understand the technical solutions in one or more embodiments of this specification, the following will be combined with the drawings in one or more embodiments of this specification to clearly and completely describe the technical solutions in one or more embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this specification, not all of the embodiments. Based on one or more embodiments of this specification, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this document.

[0013] Method Embodiment According to an embodiment of the present invention, a method for calculating the trim state of a propeller power system is provided. Figure 1 Flow chart of the method for calculating the trim state of a propeller power system according to an embodiment of the present invention; Figure 1 As shown, the method for calculating the trim state of a propeller power system according to an embodiment of the present invention specifically includes: S1. 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; 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 batteries connected in series and parallel 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, 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.

[0014] The simulation model of the aviation electric power system is established based on the above parameters. The difference between the electric aircraft of the embodiment of the present invention and other traditional aircraft using fossil fuels is the thrust. Provided by the electric power system, the simulation model of the aviation electric power system is as follows: (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.

[0015] S2. constructing a trim constraint of the electric power system according to the aviation electric power system simulation model; When the aircraft is in trim, the motor and battery are at a steady-state operating point, so the motor current and speed The rate of change is zero, so equation (1) can be simplified to: (2); The motor current in formula (2) Substituting the expression into the first two equality constraints, the balancing equation of the electric power system can be organized into the following equality constraints: (3); Solving equation (3) about , and The set of equations can determine the trim state of the propeller, motor and battery.

[0016] S3. The decoupling algorithm is used to solve the trim constraints of the electric power system to achieve the sequence solution of the trim states of the battery pack, motor and propeller.

[0017] The balancing constraint of the electric power system, that is, equation (3), contains three unknown quantities, but there are only two equations, and the equations are nonlinear and difficult to solve directly.

[0018] To this end, the embodiment of the present invention proposes a decoupling solution method of formula (3), firstly, the thrust demand of the aircraft for the propeller is calculated. Solve for the required propeller trim speed , and then substitute it into formula (3) to solve and The details are as follows: Trimming thrust for electric aircraft Provided by the propeller, the propeller thrust is given by the following 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 aircraft's flight speed, and the trim thrust requirement Substituting into formula (4), we can get The equation is as follows: (5); Organize it into about speed The standard quadratic form of is: (6); The above formula is about the speed The two solutions of the quadratic equation are: (7); To ensure that the trim speed is a positive number, the first solution in equation (7) should be taken: (8); This is the propeller speed that satisfies the electric aircraft's trimmed flight state.

[0019] The specific steps to calculate the motor trim duty cycle are as follows: First, substitute the equilibrium speed obtained by equation (8) into the second fraction of equation (3) to obtain: (9); This is available Express ; Substituting equation (9) into the first fraction of equation (3), we can get: (10); Rearrange formula (10) into The quadratic equation of : (11); The two solutions of the equation are: (12); Choose the second solution as the trim duty cycle: (13); The propeller torque is Defined as: (14); The specific steps to calculate the cell balance load current are as follows: Substituting the trim duty cycle obtained from equation (13) into equation (9) yields the trim battery current: (15); In this way, all state quantities of the electric power system's balancing state are obtained.

[0020] 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: (16); in, is the trim lift coefficient, is the reference area, and is a constant coefficient that reflects the aerodynamic drag characteristics of an 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 standard atmospheric model fitting formula: (17); The propeller power system trim state calculation method provided in the embodiment of the present invention is compared with the trim method proposed in the comparative method (Barufaldi GN, Morales MAV, da Silva RGA et al. Energy Optimal Climb Performance of Electric Aircraft [A]. AIAAScitech 2019 Forum [C]. AIAA, 2019, 1-19), thereby proving the effectiveness of the propeller power system trim state calculation method provided in the embodiment of the present invention: The trimming method in the above comparison method sets the thrust of the electric aircraft motor-driven propeller to: (18); in, is the overall efficiency of the electric power system, is the maximum power of the electric power system, is the normalized electric propeller speed. The trim speed of the electric aircraft is: (19); in, is the maximum propeller speed.

[0021] The eVTOL aircraft parameters used in the embodiment of the present invention are shown in Table 1: Table 1 eVTOL aircraft parameters

[0022] A series of flight condition combinations (including: speed, altitude, power consumption) within the expected flight range of the example electric aircraft were selected to compare the two methods. Table 2 is a comparison of the trimming results of Example 1 and Comparative Example 1. Table 2 shows the propeller trim 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).

[0023] Table 2 Comparison of the balancing results of the calculation method provided by the embodiment of the present invention and the comparative example 1

[0024] In addition, Example 1 additionally provides the motor controller duty cycle and the battery load current. Figure 3 A comparison of the propeller trim speed calculation method of the propeller power system provided by the embodiment of the present invention and the propeller trim speed calculation method of the comparative example 1 under different flight states is given. Figure 4 The drag residual, that is, the absolute value of the difference between the propeller total thrust and the aerodynamic drag, of the propeller power system trim state calculation method disclosed in the embodiment of the present invention and comparative example 1 is given.

[0025] according to Figure 3 and Figure 4 It can be seen that the method for calculating the trim state of a propeller power system provided by the embodiment of the present invention takes into account the influence of the air flow caused by the flight speed on the propeller performance, and the trim accuracy is significantly improved. The trim residuals of the method for calculating the trim state of a propeller power system provided by the embodiment of the present invention are all below 10N, while the comparative residuals are all above 20N, and the maximum can reach more than 900N. The method of the present invention can additionally reveal the duty cycle of the motor controller and the battery load current in the trim state, thereby more accurately evaluating the energy utilization efficiency of the electric power system.

[0026] By adopting the embodiment of the present invention, the following beneficial effects are achieved: by adopting the embodiment of the present invention, a dynamic simulation model of the aviation electric power system is established, and it is converted into a set of equations with equal constraints according to the trimming characteristics; a decoupling calculation method is introduced for the set of equations with equal constraints on the electric power system, firstly, 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 cycle of the motor is solved, and finally the trimming load current of the battery is solved; in the solution process, the quadratic equations about the trimming state quantity need to be solved multiple times, and the invention determines the effective solution according to the range of the model parameters of the electric power system components and the state constraint characteristics; and the solution process does not need to be iterated repeatedly, and the key state quantity of the trimming of the electric power system can be quickly determined. It solves the problem that the existing trimming analysis method ignores the influence of the flight speed on the propeller performance, and does not consider the performance constraints between the electric power system components 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.

[0027] Device Example 1 According to an embodiment of the present invention, a propeller power system trim state calculation device is provided. Figure 2 Schematic diagram of a propeller power system trim state calculation device according to an embodiment of the present invention. Figure 2 As shown, the propeller power system trim state calculation device of the embodiment of the present invention specifically includes: A model building module 20 is used to build 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 22, configured to construct a trim constraint of the electric power system according to the aviation electric power system simulation model; The trim solution module 24 is used to solve the trim constraints of the electric power system using a decoupling algorithm to achieve a sequence solution of the trim states of the battery pack, the motor and the propeller.

[0028] This device embodiment is a device embodiment that corresponds one-to-one to the above method embodiment. Please refer to the above method embodiment for the specific implementation of each module, which will not be repeated here.

[0029] Device Example 2 According to an embodiment of the present invention, an electronic device is provided, including: processor; and, A memory is arranged to store computer executable instructions, which when executed cause the processor to perform the steps of the above method embodiments.

[0030] Device Example 3 According to an embodiment of the present invention, a storage medium is provided for storing computer executable instructions, wherein the computer executable instructions implement the steps of the above method embodiment when executed.

[0031] 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 it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, 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 solution of the battery pack, motor and propeller trim state sequence.

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 propeller trim speed in the trim constraint of the electric power system , and then solve the motor trim duty cycle and battery trim load current.

3. The method according to claim 2, characterized in that 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.

4. The method according to claim 3, 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.

5. The method according to claim 4, 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.

6. The method according to claim 5, 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.

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

8. 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 a sequence solution of the trim states of the battery pack, motor and propeller.

9. 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 7.

10. 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 claimed in any one of claims 1 to 7.

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