Engine torque control system for parallel coaxial hybrid power unmanned aerial vehicle

Abstract

The invention belongs to the technical field of aviation power and unmanned aerial vehicle control, and discloses an engine torque control system for a parallel coaxial hybrid power unmanned aerial vehicle, and the system comprises a demand torque calculation module which distributes the demand torque of an engine and a motor according to the current flight state of the unmanned aerial vehicle, an energy management strategy and sensor information; the permanent magnet synchronous motor torque observation module is used for calculating a motor observation torque according to the current motor phase current and electrical angle information; the engine torque observation module is used for carrying out on-line observation on the engine torque by designing a torque observer to obtain an engine observation torque; and the torque feedback control module adopts a PI controller, takes the required torque of the engine and the actual torque of the engine as input, and realizes adjustment of control parameters through feedback. By the adoption of the engine torque control system, the rotating speed keeping capacity, the torque distribution efficiency and the energy utilization efficiency are improved, and collaborative optimization of the battery charge state and the propulsion performance is considered.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aviation power and unmanned aerial vehicle control technology, and particularly relates to an engine torque control system for a parallel coaxial hybrid power unmanned aerial vehicle. BACKGROUND

[0002] In the field of unmanned aerial vehicle technology, for a coaxial rigid coupling hybrid power system, the propeller aerodynamic load will change rapidly with the flight task. The traditional single-machine driving scheme relying only on the engine cannot simultaneously consider speed stability and response speed, and in complex task scenarios, problems such as large speed fluctuation and torque output lagging are likely to occur, which affects the flight performance and task execution efficiency of the unmanned aerial vehicle.

[0003] The parallel coaxial hybrid power scheme can utilize the transient torque compensation and energy recovery provided by the motor through the cooperative work of the engine and the motor, and to some extent, the defects of the traditional single-machine scheme are alleviated. However, in this hybrid architecture, the accurate observation and closed-loop regulation of the engine torque, as well as the cooperative distribution of the engine and motor torques, are still key difficulties in improving the overall efficiency and dynamic performance. If the actual engine torque cannot be accurately obtained, the torque distribution strategy will be difficult to accurately execute, thereby reducing the energy utilization efficiency; at the same time, the lack of effective closed-loop control will make the engine output torque difficult to quickly track the required torque, affecting the stability of the unmanned aerial vehicle in the rapid load change scenario.

[0004] Therefore, there is an urgent need for a system that can realize accurate observation, closed-loop control and cooperative distribution of engine torque with motor torque to meet the performance requirements of the parallel coaxial hybrid power unmanned aerial vehicle. SUMMARY

[0005] The purpose of the present application is to provide an engine torque control system for a parallel coaxial hybrid power unmanned aerial vehicle, which realizes accurate observation, closed-loop control and cooperative distribution of engine torque with motor torque to meet the performance requirements of the parallel coaxial hybrid power unmanned aerial vehicle.

[0006] To achieve the above-mentioned purpose, the present application provides an engine torque control system for a parallel coaxial hybrid power unmanned aerial vehicle, comprising a required torque calculation module, a permanent magnet synchronous motor torque observation module, an engine torque observation module and a torque feedback control module. The required torque calculation module allocates the required torque of the engine and the motor according to the current unmanned aerial vehicle flight state, energy management strategy and sensor information. The permanent magnet synchronous motor torque observation module calculates the motor observed torque according to the current motor phase current and electric angle information. The engine torque observation module performs online observation on the engine torque by designing a torque observer to obtain the engine observed torque. Torque feedback control module, PI controller is used, the engine demand torque and engine actual torque as input, through the feedback to achieve the adjustment of control parameters.

[0007] Preferably, the demand torque calculation module is implemented, the specific process is as follows: Step S11, calculate the task target propeller demand pull; According to the flight speed, environmental information including the corresponding atmospheric density and temperature of the altitude collected by the sensor, combined with the target flight attitude corresponding to the flight task including hovering, cruising and climbing, the task target propeller demand pull is calculated through the propeller aerodynamic model As follows: ; Wherein, The propeller pull coefficient is; The atmospheric density is; The propeller speed is; The propeller diameter is; Step S12, calculate the total demand torque of the propeller; Based on the demand pull obtained in step S11 , combined with the propeller load model, the total demand torque As follows: ; Wherein, The propeller torque coefficient is; Step S13, distribute the engine and motor target torque; The energy management strategy takes , battery state of charge SOC, motor state, engine state as input, distributes the engine target torque And the motor target torque ; The torque range corresponding to the engine working is set as , the torque range corresponding to the motor working is , and the output shaft speed target value is ; The specific distribution logic of energy management strategy is as follows: (1) When the battery , the motor output torque is reduced first, the engine torque distribution is increased, the engine works in the upper limit of the torque range, and the motor is used for energy recovery, the motor is switched to generator mode, the motor target torque Is negative, as follows: ; ; Wherein, To recover the torque of the motor, take the value in the torque range of the motor; (2) When the battery , make the engine and motor work in the torque range, as follows: ; , ; (3) When the battery , prefer to increase the motor output torque, the motor switches to the motor mode, reduces the engine torque distribution, and makes the motor work in the upper limit of the torque range, as follows: ; .

[0008] Preferably, the implementation of the permanent magnet synchronous motor torque observation module is as follows: Step S21, collect the original signal; Collect the instantaneous values of the three-phase stator currents of the motor through the current sensor , and , and collect the motor electrical angle through the encoder; Step S22, Clark transformation, i.e. three-phase stationary coordinate system is transformed into two-phase stationary coordinate system; Transform the three-phase currents , and into two-phase stationary coordinate system currents and , eliminating the coupling relationship of the three-phase currents, as follows: ; Step S23, Park transformation, i.e. two-phase stationary coordinate system is transformed into two-phase rotating coordinate system; Transform and into the direct-axis current and the quadrature-axis current in the two-phase rotating coordinate system that rotates synchronously with the motor rotor, so that the current components are directly related to the motor torque control, as follows: ; Step S24, calculate the motor electromagnetic torque; According to the mathematical model of the permanent magnet synchronous motor, use and and the motor parameters to calculate the motor observed torque , as follows: ; wherein, is the number of pole pairs; is the direct axis inductance; is the quadrature axis inductance; is the permanent magnet flux linkage.

[0009] Preferably, the implementation of the engine torque observation module is as follows: Step S31, establishing the co-axial shaft system dynamics equation; Since the engine and the motor are rigidly connected in the same shaft, the co-axial shaft system dynamics equation is established as follows: ; wherein, is the equivalent rotational inertia of the shaft system; is the angular acceleration of the shaft system; is the engine output torque; is the motor torque; B is the viscous damping coefficient of the shaft system; is the propeller load torque, which is calculated by the propeller load model as follows: ; n = ω / (2π); wherein, is the rotational speed; Step S32, constructing a third-order extended state observer; Rewrite the co-axial shaft system dynamics equation into a state space form, and define the state variables , , wherein is the unmodeled disturbance; the state space equation is as follows: ; The output equation is: ; Based on the above state space equation, a third-order extended state observer is constructed, and the observer equation is as follows: ; wherein, , and are the state variables of the observer, respectively; , and are the observation values of , and , respectively; , and are the observer gains; Step S33, calculating the engine observed torque and processing; According to the observer output , combined with the shafting parameters and the propeller load torque, the engine observation torque is calculated reversely , as shown below: ; To avoid the impact of sudden changes in the observation torque on subsequent control, the is limited and smoothed, and the specific process is as follows: (1) Limiting processing: Set the maximum output torque and the minimum output torque of the engine, if , take ; if , take ; (2) Smooth processing: A first-order low-pass filter is used to smooth the after limiting, and the filter transfer function is , where is the filter time constant, and the final output is the processed engine observation torque .

[0010] Preferably, the implementation of the torque feedback control module is as follows: Step S41, calculate the torque error; Get the engine target torque output by the demand torque calculation module, and the output by the engine torque observation module, calculate the torque error , as shown below: ; Step S42, PI controller calculation; Input the torque error into the PI controller to calculate the engine control parameter adjustment amount; For throttle opening adjustment, the PI controller output is: ; Where, is the throttle opening adjustment amount; and are throttle opening control PI parameters; is the proportional coefficient; is the integral coefficient; For injection timing adjustment, the PI controller output is: ; Where, is the injection timing adjustment amount; and PI parameters for injection timing control are controlled; For ignition timing adjustment, the PI controller output is: ; Wherein, is the ignition advance angle adjustment amount; and PI parameters for ignition timing control; Step S43, control adjustment is performed; The adjustment amount of the PI controller output 、 Or is sent to the engine actuator to adjust the throttle opening, injection timing or ignition timing, so that the engine output torque quickly tracks the engine target torque , realizing accurate control of the engine torque.

[0011] A UAV includes a propulsion system, an energy system and a flight control system, the propulsion system adopts a parallel hybrid architecture with the engine and the permanent magnet synchronous motor coaxially rigidly connected, and integrates the engine torque control system described above.

[0012] A computer readable storage medium has a computer program stored thereon, and the computer program is executed by a processor to implement the processes described above.

[0013] Therefore, the engine torque control system for parallel coaxial hybrid UAVs described above has the following beneficial effects: (1) Significantly improve the speed stability: the engine torque observation module of the present application can obtain the actual torque in real time, and the PI closed-loop control can make the engine torque quickly track the target value, suppress the speed fluctuation, ensure the flight attitude stability, and adapt to the rapid load change scene.

[0014] (2) Dynamic response speed is improved: the fast adjustment characteristics of the permanent magnet synchronous motor torque are used, and the closed-loop feedback of the engine torque is used to form a collaborative mechanism of "motor transient compensation + engine steady-state output"; in complex task scenarios (such as sudden acceleration and sudden wind disturbance), the dynamic response speed of the total torque of the system is improved, and the decline of flight performance caused by power lag is avoided.

[0015] (3) Optimize energy distribution efficiency, reduce energy consumption and prolong endurance: the demand torque calculation module is based on an energy management strategy, and dynamically allocates the engine and motor torque according to the state of charge of the battery; the engine torque observation module calculates the actual output through the shaft dynamics equation, avoids the waste of excessive fuel injection or throttle opening caused by the deviation between the demand torque and the actual torque, and reduces the loss of invalid energy.

[0016] (4) Enhance system reliability and adaptability: three order extended state observer can not only estimate engine torque, but also compensate for unmodeled disturbances in real time, improve the robustness of torque observation in the case of sensor noise or parameter drift, avoid control instability caused by observation failure; the system corrects the propeller load model through environmental parameters, and can accurately calculate the required torque under different altitudes and temperatures.

[0017] (5) Engineering value: without additional hardware sensors, engine torque observation relies on existing sensors, and is achieved through algorithm fusion, avoiding the addition of high-precision torque sensors, while reducing hardware failure rate and control complexity and cost; the core algorithm is based on a general control chip and can be directly transplanted to different types of parallel coaxial hybrid unmanned aerial vehicles, and the control logic is highly portable.

[0018] The technical solutions of the present application will be further described in detail below with the help of drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a general block diagram of an engine torque control system for a parallel coaxial hybrid unmanned aerial vehicle of the present application; Figure 2 is a torque feedback control model diagram of the present application. DETAILED DESCRIPTION

[0020] The technical solutions of the present application will be further described in detail below with the help of drawings and examples.

[0021] As shown in Figure 1 , an engine torque control system for a parallel coaxial hybrid unmanned aerial vehicle of the present application is applied to a parallel hybrid system of an unmanned aerial vehicle, wherein the engine and the motor (including both functions of an electric motor and a generator) are coaxially rigidly connected in a hybrid power architecture.

[0022] The engine torque control system for a parallel coaxial hybrid unmanned aerial vehicle proposed by the present application comprises the following modules: a required torque calculation module, a permanent magnet synchronous motor torque observation module, an engine torque observation module, and a torque feedback control module.

[0023] The required torque calculation module can allocate the required torque of the engine and the motor according to the current unmanned aerial vehicle flight state, energy management strategy, and sensor information. The permanent magnet synchronous motor torque observation module can calculate the motor observation torque according to the current motor phase current and electrical angle information. The engine torque observation module can observe the engine torque online through the design of a torque observer to obtain the engine observation torque.

[0024] Torque feedback control module, taking engine demand torque and engine actual torque as input, adjusts control parameters (including but not limited to throttle opening, fuel injection time, ignition time) through feedback, thereby improving engine output performance, to improve the speed maintaining ability, torque distribution efficiency and energy utilization efficiency of the coaxial hybrid unmanned aerial vehicle under rapid load change and complex task scenarios.

[0025] Embodiment 1 Step S1, realization of demand torque calculation module.

[0026] According to the task demand, the environmental information and flight speed collected by the sensor are calculated to obtain the task target propeller demand pull; the total demand torque is output through the propeller load model; finally, based on the energy management strategy, the target torque of the motor and the engine is distributed according to the demand torque, the battery SOC, the motor and the engine state information, the engine and the motor are maintained in the high efficiency working area under the condition of meeting the task demand, and the output shaft speed is stable.

[0027] Step S11, calculate the task target propeller demand pull.

[0028] According to the flight speed collected by the sensor , environmental information (altitude , atmospheric density , temperature ), combined with the target flight attitude corresponding to the flight task (such as hovering, cruising, climbing), the task target propeller demand pull is calculated through the propeller aerodynamic model , as shown below: ; Among them, is the propeller pull coefficient (determined by the propeller model); is the atmospheric density; is the propeller speed (unit: r / s); is the propeller diameter (unit: m).

[0029] In actual calculation, the propeller pull coefficient needs to be corrected according to different flight attitudes , for example, the hovering pull coefficient is taken in hovering state, and the cruising pull coefficient is taken in cruising state.

[0030] Step S12, calculate the total demand torque of the propeller.

[0031] Based on the demand pull obtained in step S11 , combined with the propeller load model, the total demand torque is calculated, as shown below: ; wherein, is the propeller torque coefficient (related to propeller model, flight attitude, obtained by propeller performance manual or experimental calibration).

[0032] Step S13, distribute engine and motor target torque.

[0033] The energy management strategy takes battery state of charge SOC, motor state (current power , speed ), engine state (current power , speed ) as input, follows the principle of "engine and motor maintaining in high efficiency working area, ensuring output shaft speed stability, and considering battery SOC balance", and distributes engine target torque and motor target torque .

[0034] Set the torque range corresponding to the engine high efficiency working area as , the torque range corresponding to the motor high efficiency working area as , and the output shaft speed target value as . Then the specific distribution logic of the energy management strategy is as follows: (1) When the battery (high threshold 80%) is, preferentially reduce the motor output torque, increase the engine torque distribution, make the engine work near the upper limit of the high efficiency area, and at the same time use the motor for energy recovery, the motor is switched to generator mode, and the motor target torque is negative, as shown below: ; ; wherein, is the motor recovery torque, taking the value in the motor high efficiency recovery torque range.

[0035] (2) When the battery , make the engine and motor work in the high efficiency area, as shown below: ; , ; (3) When the battery , preferentially increase the motor output torque, the motor is switched to motor mode, reduce the engine torque distribution, make the motor work near the upper limit of the high efficiency area, as shown below: ; ; Here, the energy management unit inputs the required torque into the control units of the engine and electric motor.

[0036] Step S2: Implementation of the permanent magnet synchronous motor torque observation module.

[0037] The permanent magnet synchronous motor torque observation module collects the motor phase current and electrical angle in real time through current sensors and encoders, and obtains the observed motor torque through coordinate transformation and mathematical model calculation. .

[0038] Step S21: Acquire the raw signal.

[0039] The instantaneous value of the three-phase stator current of the motor is collected by a current sensor. , and The electric angle of the motor is collected by the encoder. (Unit: rad)

[0040] Step S22, Clark transformation (three-phase stationary coordinate system → two-phase stationary coordinate system).

[0041] Three-phase current , and Transformed into current in a two-phase stationary coordinate system and This eliminates the coupling relationship of the three-phase currents, as shown below: ; Step S23, Park transformation (two-phase stationary coordinate system → two-phase rotating coordinate system).

[0042] Will and Transformed into direct-axis current in a two-phase rotating coordinate system (dq coordinate system) that rotates synchronously with the motor rotor. and cross-axis current This directly links the current component to the motor torque control, as shown below: ; Step S24: Calculate the electromagnetic torque of the motor.

[0043] Based on the mathematical model of permanent magnet synchronous motor, using and and motor parameters (number of pole pairs) Direct-axis inductor quadrature axis inductance Permanent magnet flux ), calculate the observed torque of the motor As shown below: ; Take a certain type of permanent magnet synchronous motor as an example, its parameters are 、 、 、 , if the transformation is obtained 、 , the motor observation torque is as follows: .

[0044] Step S3, realization of engine torque observation module.

[0045] The engine torque observation module is based on the co-axial shafting dynamics equation, a three-order extended state observer is constructed to realize online estimation of engine torque.

[0046] Step S31, establish co-axial shafting dynamics equation.

[0047] Since the engine and the motor are rigidly connected coaxially, the co-axial shafting dynamics equation is established as follows: ; Among them, is the equivalent moment of inertia of the shafting (unit: kg·m 2 , obtained by superimposing the moments of inertia of the engine, motor, transmission shaft and propeller); is the angular acceleration of the shafting (unit: rad / s 2 , obtained by differentiating the rotational speed ); is the engine output torque (to be observed); is the motor torque (obtained in step S24 ); B is the viscous damping coefficient of the shafting (unit: N·m·s / rad, calibrated by experiment); is the propeller load torque, calculated by the propeller load model as follows: ; n=ω / (2π).

[0048] Among them, is the rotational speed.

[0049] Step S32, construct a three-order extended state observer.

[0050] Rewrite the co-axial shafting dynamics equation into state space form, define state variables 、 、 ( is the unmodeled disturbance), the state space equation is as follows: ; The output equation is: .

[0051] Based on the above state space equation, a three-order extended state observer is constructed, and the observer equation is as follows: ; wherein, , and are the state variables of the observer; , and are the observation values of , and ; , and are the observer gains (determined by the pole placement method to ensure the convergence of the observer, for example, take , , , is the observer bandwidth, usually 10-50 rad / s.

[0052] Step S33, calculate the engine observation torque and process.

[0053] According to the observation value of , combined with the shaft system parameters and the propeller load torque, the engine observation torque is calculated as follows: ; In order to avoid the sudden change of the observation torque affecting the subsequent control, the is limited and smoothed, and the specific process is as follows: (1) Limiting processing: set the maximum output torque of the engine and the minimum output torque (determined by the engine performance parameters), if , take ; if , take ; (2) Smooth processing: a first-order low-pass filter is used to smooth the after limiting, and the filter transfer function is , wherein is the filter time constant (usually 0.01-0.1s), and the final output is the processed engine observation torque .

[0054] Step S4, realization of torque feedback control module.

[0055] The torque feedback control module adopts a PI (proportional-integral) controller, taking the error between the engine target torque and the observed torque as input, and outputting the adjustment amount of the engine control parameter (throttle opening, injection pulse width or ignition time) to realize closed-loop control. The torque feedback control model is shown in FIG. 1. Figure 2

[0056] Step S41, calculate the torque error.

[0057] The engine target torque output by the demand torque acquisition module and the observed torque output by the engine torque observation module are input into the PI controller to calculate the torque error , as shown below: .

[0058] Step S42, PI controller calculation.

[0059] The torque error is input into the PI controller to calculate the engine control parameter adjustment amount.

[0060] For throttle opening adjustment, the PI controller output is: ; wherein, is the throttle opening adjustment amount; and are the throttle opening control PI parameters. is the proportional coefficient; is the integral coefficient; determined by engineering setting method, for example, using trial and error method, first set , increase until the system appears slight oscillation, then decrease until the oscillation disappears, and then gradually increase to make the system have no static error and the response speed meet the requirements.

[0061] For injection time adjustment, the PI controller output is: ; wherein, is the injection time adjustment amount; and are the injection time control PI parameters.

[0062] For ignition time adjustment, the PI controller output is: ; wherein, is the ignition advance angle adjustment amount; and ​To control the PI parameters at the ignition timing.

[0063] Step S43: Perform control adjustment.

[0064] The adjustment amount of the PI controller output (or , The signal is sent to the engine actuator to adjust the throttle opening (or injection timing, ignition timing) so that the engine output torque quickly tracks the engine target torque. This enables precise control of engine torque.

[0065] For example, when When the actual engine torque is less than the required torque, When the value is positive, the throttle opening increases, increasing the engine's intake air volume and thus improving the engine's output torque; when... hour, A negative value reduces the throttle opening and lowers the engine's output torque.

[0066] Example 2 To verify the effectiveness of the system of the present invention, this embodiment constructs a parallel coaxial hybrid unmanned aerial vehicle experimental platform, and the experimental parameters are as follows: The engine model is a small gasoline engine with a maximum power of 20kW and a maximum torque of 80N·m; the permanent magnet synchronous motor parameters are: number of pole pairs. Direct-axis inductor quadrature axis inductance Permanent magnet flux Equivalent moment of inertia of shaft system Shaft system viscous damping coefficient propeller diameter propeller thrust coefficient propeller torque coefficient .

[0067] The experimental scenario was set as a drone switching from hovering to climbing (a rapid load change scenario). The performance of the system of this invention was compared with that of a traditional closed-loop control system without torque observation. The experimental results are as follows: Speed ​​maintenance capability: When the load changes, the speed fluctuation of the system of this invention is less than 5%, while the speed fluctuation of the traditional system is greater than 15%; Torque response speed: The response time of the engine torque tracking demand of the system of this invention is less than 0.2s, while the response time of the traditional system is greater than 0.5s; Energy utilization efficiency: In a 1-hour cruise test, the energy utilization efficiency of the system of the present invention is 12% higher than that of the traditional system.

[0068] The experimental results show that the system can effectively improve the performance of the parallel coaxial hybrid power unmanned aerial vehicle under rapid load change and complex task scenarios.

[0069] The application further provides an unmanned aerial vehicle, comprising a propulsion system, an energy system and a flight control system, wherein the propulsion system adopts a parallel hybrid architecture in which an engine and a permanent magnet synchronous motor are rigidly connected in a coaxial manner, and the engine torque control system is integrated.

[0070] If the above functions are realized in the form of software function units and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the application or the part of the technical solutions that essentially contribute to the prior art can be embodied in the form of a software product stored in a storage medium, including a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device) to execute all or part of the steps of the method described in the various embodiments of the application. The aforementioned storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk and various program code storage media.

[0071] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered a list of executable instructions for implementing logic functions, and can be specifically embodied in any computer-readable medium for use by an instruction execution system, apparatus or device, such as a computer-based system, a system including a processor or other system that can fetch and execute instructions from the instruction execution system, apparatus or device, or in conjunction with these instructions. For the purpose of this specification, the "computer-readable medium" can be any device that can contain, store, communicate, propagate or transport programs for use by an instruction execution system, apparatus or device, or in conjunction with these instruction execution systems, apparatus or devices.

[0072] More specific examples (a non-exhaustive list) of the computer-readable medium include the following: an electrical connection (electronic) having one or more wires, a portable computer diskette (magnetic), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium can also be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, for instance via an optical scanner, then compiled, interpreted, or otherwise processed, and stored in a computer memory in a form that is then accessible for execution by a computer.

[0073] It is worth noting that the contents not elaborated in the present application are all prior art and are well known to those skilled in the art.

[0074] Therefore, the application adopts the above-mentioned engine torque control system for a parallel coaxial hybrid unmanned aerial vehicle, and through the integrated design of "precise observation-intelligent distribution-closed loop control", breakthroughs are achieved in three core dimensions of dynamic performance, energy efficiency and reliability, so that the parallel coaxial hybrid unmanned aerial vehicle can adapt to rapid load changes, complex environments and long endurance task requirements, and provides key technical support for the engineering application of hybrid unmanned aerial vehicles.

[0075] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or equivalently replace the technical solutions of the present application, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. An engine torque control system for a coaxial hybrid powered unmanned aerial vehicle in parallel, characterized by, The torque feedback control module adopts a PI controller, taking the engine demand torque and the actual engine torque as inputs, and adjusts the control parameters through feedback. The demand torque calculation module is implemented in the following specific process: Step S11, calculate the task target propeller demand tension; Step S12, calculate the total demand torque of the propeller; Step S13, allocate the engine and motor target torque; 2. The engine torque control system for a coaxial hybrid unmanned aerial vehicle in parallel according to claim 1, characterized in that, The implementation of the permanent magnet synchronous motor torque observation module is as follows: Step S21, collect the original signal; According to the flight speed collected by the sensor, environmental information including the atmospheric density and temperature corresponding to the altitude, and the target flight attitude corresponding to the flight task including hovering, cruising and climbing, the required pulling force of the propeller for the task target is calculated through a propeller aerodynamic model As shown below: ； wherein, is the propeller drag coefficient; is the atmospheric density; is the propeller rotational speed; is the propeller diameter; Step S22, Clark transformation, i.e. three-phase static coordinate system to two-phase static coordinate system; Based on the demand tension obtained in step S11 , in combination with the propeller load model, the total demand torque is calculated , as shown below: ； wherein, is the propeller torque coefficient; Step S23, Park transformation, i.e. two-phase static coordinate system to two-phase rotating coordinate system; The energy management strategy takes as inputs battery state of charge SOC, motor state, engine state, and distributes engine target torque and motor target torque ; The torque range corresponding to the engine working is set as , the torque range corresponding to the motor working is set as , and the output shaft rotating speed target value is ; the specific distribution logic of the energy management strategy is as follows: (1) When the battery is low, the motor output torque is reduced preferentially, the engine torque distribution is increased, the engine is operated at the upper limit of the torque range, and the motor is used for energy recovery. The motor switches to the generator mode, and the motor target torque is negative, as shown below: ； ； wherein, is the motor recovery torque, taken as a value in the range of the motor torque; (2) When the battery is low, the engine and motor are both operated in the torque range, as follows: ； ， ； (3) When the battery is low, the motor output torque is increased preferentially, the motor is switched to the motor mode, the engine torque distribution is reduced, and the motor is operated at the upper limit of the torque range, as shown below. ； 。 3. The engine torque control system for a coaxial hybrid power unmanned aerial vehicle in parallel according to claim 1, characterized in that, Step S24, calculate the motor electromagnetic torque; The implementation of the engine torque observation module is as follows: Collecting three-phase stator current instantaneous value of motor through current sensor , and Collecting motor electric angle through encoder ; Step S31, establish the co-axial shaft system dynamics equation; transforming three-phase currents , and into currents and in a two-phase stationary coordinate system, eliminating the coupling relationship of the three-phase currents, as follows: ； Since the engine and motor are rigidly connected coaxially, the co-axial shaft system dynamics equation is established as follows: Transforming and the direct-axis current in a two-phase rotating coordinate system that rotates synchronously with the motor rotor and the quadrature-axis current so that the current components are directly linked to motor torque control as follows: ； n=ω / (2π); Based on the mathematical model of permanent magnet synchronous motor, using and And motor parameters, calculate the observed torque of the motor. As shown below: ； wherein, is the number of pole pairs; is the direct axis inductance; is the quadrature axis inductance; is the permanent magnet flux linkage.

4. The engine torque control system for a coaxial hybrid power unmanned aerial vehicle in parallel according to claim 1, characterized in that, Step S32, construct a three-order extended state observer; Based on the above state space equation, a three-order extended state observer is constructed, and the observer equation is as follows: Step S33, calculate the engine observed torque and process it; ； wherein, is the shafting equivalent moment of inertia; is the shafting angular acceleration; is the engine output torque; is the motor torque; B is the shafting viscous damping coefficient; is the propeller load torque, calculated by the propeller load model as follows: ； The implementation of the torque feedback control module is as follows: wherein N is rotational speed; Step S41, calculate the torque error; The dynamics equations of the coaxial shafting are rewritten in the state space form, and the state variables are defined , , where is the unmodeled disturbance; the state space equation is as follows: ； The output equation is then: ; Step S42, PI controller calculation; ； wherein , and are state variables of the observer; , and are observation values of , and ; , and are observer gains; For throttle opening adjustment, the PI controller output is: According to the observer output , combined with the shafting parameters and the propeller load torque, the engine observed torque is calculated reversely , as shown below: ； To avoid the impact of sudden change of the observed torque on subsequent control, the observed torque is limited and smoothed, and the specific process is as follows: Limiting and smoothing the observed torque (1) Limiting processing: set the maximum output torque of the engine and the minimum output torque , if , take ; if , take ; (2) Smoothing processing: a first-order low-pass filter is used to smooth the amplitude-limited engine observed torque , and the filter transfer function is , where is a filter time constant, and the final output is the processed engine observed torque .

5. The engine torque control system for a coaxial hybrid power unmanned aerial vehicle in parallel according to claim 1, characterized in that, For injection timing adjustment, the PI controller output is: For ignition timing adjustment, the PI controller output is: the engine target torque output by the demand torque acquisition calculation module and the engine torque observation module output , the torque error is calculated as follows: ； Step S43, execute control adjustment; correcting the torque error inputting the PI controller to calculate the engine control parameter adjustment amount; The propulsion system adopts a parallel hybrid architecture with the engine and permanent magnet synchronous motor rigidly connected coaxially, and integrates the engine torque control system according to any one of claims 1-5. ； wherein, is a throttle opening degree adjustment amount; and is a throttle opening degree control PI parameter; is a proportional coefficient; is an integral coefficient; The computer program is executed by a processor to realize the process according to any one of claims 1-5. ； wherein, is the injection timing adjustment amount; and is the injection timing control PI parameter; ​ ； wherein, is the ignition advance angle adjustment amount; and is the ignition timing control PI parameter; ​ The adjustment amount of the PI controller output , or The signal is sent to the engine actuator to adjust the throttle opening, injection timing, or ignition timing, so that the engine output torque quickly tracks the engine target torque. This enables precise control of engine torque.

6. A drone, characterized in that, ​ 7. A computer readable storage medium storing a computer program, characterized in that, ​

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