Turboprop engine propeller rotating speed control method for unmanned aerial vehicle

Abstract

The invention provides a turboprop engine propeller rotating speed control method for an unmanned aerial vehicle, and the control method comprises a propeller rotating speed drift automatic compensation rule which is used for solving the problem of propeller balance rotating speed drift caused by speed selection and step loss of a stepping motor; the control method further comprises a propeller rotating speed and step number relation on-line calibration method, the on-line calibration method does not need to run a special ground test program, other ground tests of the engine can be combined, and calibration can be completed through simple on-line operation. According to the invention, two major problems of a stepping motor speed selection structure of a small and medium-sized turboprop engine propeller speed regulator for an unmanned aerial vehicle are solved, and precise control of the rotating speed of the propeller in an unmanned aerial vehicle mode is realized.

Description

Technical Field

[0001] The invention relates to the technical field of aviation turboprop engines, and in particular to a method for controlling the propeller speed of a turboprop engine for an unmanned aerial vehicle. Background Art

[0002] With the vigorous development of UAV technology, more large military / civilian high-end UAVs have begun to use turboprop engines as their power source. In order to adapt to the widespread use of UAV fly-by-wire flight control, the propeller speed regulator of the turboprop engine has been transformed from the original mechanical control system to an electronic control system. The propeller speed regulator adopts the original core centrifugal flyweight mechanical hydraulic control structure unchanged, and replaces the original mechanical control speed lever with an electromechanical hybrid configuration electronic control speed regulator for electronic speed adjustment by a stepper motor. The electronically controlled propeller speed regulator realizes the propeller electronic speed control function by integrating functional components such as stepper motors, reverse propeller solenoid valves, centrifugal flyweights, and beta valves, meeting the requirements of UAVs for electronic integrated control of engines and propellers and the electronic control requirements of UAV fly-by-wire flight control systems. The engine electronic controller receives the power demand command issued by the UAV, automatically solves the required propeller speed, and solves the number of steps required for the stepper motor to run in the calibration data table by interpolation method based on the propeller speed. The electronic controller sends a stepping command to the stepper motor based on the step count result, and the stepper motor runs the corresponding number of steps to the corresponding speed selection position in a step counting manner to select the propeller to work at different speeds. In order to solve the problem that the corresponding step number instructions of propeller speed regulators of different units are greatly different due to the mechanical manufacturing tolerances and factory commissioning test tolerances of different propeller speed regulators, a special ground test calibration program has also been developed.

[0003] The existing technology does not solve the problem of propeller speed deviation of varying degrees during the flight of the drone caused by stepper motor step loss. The propeller cannot work at the optimal working speed and has varying degrees of speed drift. In addition, the existing ground test calibration procedure developed to address the problem of large differences in the number of step instructions of different propeller speed regulators is cumbersome and requires repeated ground start-up test verification, resulting in a waste of human and material resources. Summary of the invention

[0004] The present invention combines the principle and characteristics of the propeller speed regulator and proposes a new online calibration method for the propeller speed and a law for automatic compensation of the propeller speed offset:

[0005] a) Propeller speed online calibration method: Under the ground running test state, the propeller speed of the UAV turboprop engine is calibrated to obtain the actual running steps of the speed-selective stepper motor corresponding to the required different propeller speeds, and the steps are stored in the electronic controller as the default value.

[0006] Preferably, when the engine is in the ground running test state, the UAV operator pushes up the power lever to check the working condition of the engine. When the engine speed ng is in the range of [86%, 96%], the propeller speed should be between [2000±10]r / min. If the actual propeller speed is lower than this range, it does not meet the requirements. The operator issues the "speed selection motor step increase" command once through the communication command, and then 5 steps are added to the default calibration position of 720 steps corresponding to the speed of [2000±10]r / min. At this time, the propeller speed will increase slightly. If it still does not meet the requirements, the operator continues to issue the "speed selection motor step increase" command, and the speed continues to increase until the propeller speed stabilizes between [2000±10]r / min. At this time, the UAV operator issues the "2000r / min calibration" communication command, and the actual running step number X1 of the current speed selection stepping motor replaces the default 720 steps and is stored in the electronic controller. The updated X1 step number is used as the default value in subsequent operation.

[0007] Preferably, when the engine is in the ground running test state, the UAV operator pushes up the power lever to check the engine working condition. When the engine speed ng≥96%, the propeller speed should be between [2200±10]r / min. If the actual propeller speed is lower than this range, it does not meet the requirements. The operator issues the "speed selection motor step increase" command once through the communication command, and then 5 steps are added to the default calibration position of 1080 steps corresponding to the [2200±10] speed. If it still does not meet the requirements, the "speed selection motor step increase" command is continued to be issued, and the speed continues to increase until the propeller speed stabilizes between [2200±10]r / min. At this time, the UAV operator issues the "2200r / min calibration" communication command, and the actual running step number X2 of the current speed selection stepper motor replaces the default 1080 steps and is stored in the controller. The updated X2 step number is used as the default value in subsequent operations.

[0008] Preferably, for different engines, more different propeller speed calibration requirements can be met by executing the same method.

[0009] b) Automatic propeller speed compensation rule: During flight, the speed selection step command CLA automatically selects the default value of the number of steps. If the actual speed monitored does not meet the requirements, the propeller speed is controlled by the automatic propeller speed compensation rule. The specific steps include: if the propeller speed is greater than the default value of the number of steps, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by a certain number of steps; if the propeller speed still does not meet the requirements, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by a certain number of steps again, and so on, until the stable range of the propeller speed meets the requirements; if the propeller speed is less than the default value of the number of steps, the electronic controller automatically issues a command to control the stepper motor to increase the number of steps by a certain number of steps; if the propeller speed still does not meet the requirements, the electronic controller automatically issues a command to control the stepper motor to increase the number of steps by a certain number of steps again, and so on, until the stable range of the propeller speed meets the requirements.

[0010] The electronic controller is powered on again, the current operation ends, and the number of speed selection step instructions returns to the calibrated state.

[0011] Preferably, during flight, when the engine speed ng ≥ 96%, the speed selection step instruction CLA automatically selects X2 steps (calibrated value), and when the power lever instruction PLA change rate is ≤ ±4° / s, it is determined after a delay of 5s that the propeller speed ns should be between [2200±10]r / min. If the propeller speed ns collected is greater than this range and is maintained within the range of [2210, 2244]r / min for more than 1s, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If the ns collected is still maintained within the range of [2210, 2244]r / min for more than 1s, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by 15 steps again, and so on, until the speed stability range meets the requirement of [2200±10]r / min. In order to distinguish stepper motor failures, the maximum automatic reduction in the number of steps of the stepper motor under this number of steps shall not exceed 105 steps;

[0012] If the collected ns is maintained at [2244,2288] for more than 1s, the electronic controller automatically sends a command to control the stepper motor to reduce the number of steps by 30 steps, so as to adjust the speed to the stable range more quickly. The above steps are repeated in sequence, and the maximum reduction does not exceed 105 steps.

[0013] Preferably, when the engine speed ng ≥ 96%, the speed selection step command CLA automatically selects the X2 step, and when the power lever PLA command change rate is ≤ ± 4° / s, after a delay of 5s, it is determined that the propeller speed ns should be between [2200 ± 10] r / min. If the acquisition of ns ≤ 2190r / min is maintained for more than 1s, the electronic controller automatically issues a command to control the stepper motor to increase the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If the acquisition of ns ≤ 2190r / min is maintained for more than 1s, the electronic controller automatically issues a command to control the stepper motor to increase the number of steps by 15 steps again, and so on. The maximum increase in the number of steps of the stepper motor does not exceed 150 steps.

[0014] Preferably, when the engine speed ng ≥ 86%, the speed selection step instruction CLA automatically selects X1 step (calibrated value), and after a delay of 5s, it is determined that the propeller speed ns should be between [2000±10]r / min. If the propeller speed ns is collected and maintained at [2000±10]r / min for more than 1s, the electronic controller automatically issues an instruction to control the stepper motor to reduce the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If the ns is collected and maintained at [2000±10]r / min for more than 1s, the electronic controller automatically issues an instruction to control the stepper motor to reduce the number of steps by 15 steps again, and so on. The maximum reduction in the number of steps of the stepper motor does not exceed 150 steps.

[0015] Preferably, when the engine speed ng≥86%, the speed selection step instruction CLA selects X1 step (calibrated value), and after a delay of 5s, it is determined that ns should be between [2000±10]r / min. If ns≤1990r / min is collected and maintained for more than 1s, the electronic controller automatically sends an instruction to control the stepper motor to increase the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If ns≤1990r / min is collected and maintained for more than 1s, the electronic controller automatically sends an instruction to control the stepper motor to increase the number of steps by 15 steps again, and so on. The maximum increase in the number of steps of the stepper motor shall not exceed 100 steps.

[0016] Preferably, when the engine speed is 94%≤ng≤96%, the speed selection step command CLA is maintained at the last state after compensation.

[0017] Beneficial effect: The existing propeller speed regulators of small and medium-sized turboprop engines for large unmanned aerial vehicles generally use stepper motors as speed selection actuators. The engine electronic controller performs speed selection open-loop control on the stepper motor by counting steps. Different step positions need to be selected for different propeller speeds. The step positions need to be calibrated according to the proprietary calibration procedure in the engine ground test for the relationship between the propeller speed and the step position. When the engine electronic controller controls the stepper motor to select the propeller speed, it first uses the table lookup interpolation method to find the calibration steps corresponding to different speeds according to the required propeller speed. The number of steps corresponding to different speeds has different default values. The controller then controls the stepper motor to run the corresponding number of steps to select the required propeller speed. However, due to the inherent step loss phenomenon of the stepper motor, there is random step loss (out of step) during operation. The number of steps lost each time is different, and the deviation speed is also different. In the same flight process, the longer the running time, the greater the cumulative deviation of the step loss, causing the propeller to deviate from its required optimal balanced working speed. Due to the limited structure of the propeller speed regulator, it is impossible to collect the stepper motor running position feedback signal according to the commonly used method of adding a displacement sensor to perform position closed-loop control to correct the deviation caused by the step loss. In the manned aircraft mode, the pilot usually uses the manual mode to fine-tune the actual propeller speed to ensure that the propeller works at the required optimal speed. In the unmanned aircraft mode, the flight mission system information that the pilot needs to pay attention to is far more than that of the manned aircraft, requiring the engine and propeller to have full autonomous control capabilities, automatically perform speed selection, and reduce the burden on the pilot. Therefore, the present invention proposes a propeller speed drift automatic compensation law to solve the propeller balance speed drift problem caused by the step loss of the stepper motor speed selection. In addition, due to the existence of mechanical manufacturing tolerances and factory commissioning test tolerances of the propeller speed regulator, different sets of propeller speed regulators select the same propeller speed and there are large differences in the corresponding actual step number instructions. It is necessary to repeatedly perform the engine ground test operation calibration program to find the relationship between the propeller speed and the step number of the stepper motor, and write the corresponding relationship between the actual step number and the speed into the controller program. The calibration process is cumbersome and there is a large waste of human and material resources. To this end, the present invention also proposes an online calibration method for the relationship between propeller speed and number of steps. This method does not require running a special ground test program, and can be combined with other ground tests of the engine to complete the calibration through simple online operations. Through the above two methods, the two major problems of the stepper motor speed selection structure of the propeller speed regulator of small and medium-sized turboprop engines for drones are solved, and the precise control of the propeller speed in drone mode is achieved. DETAILED DESCRIPTION

[0018] Taking a certain type of turboprop engine as an example, the optimal flight operating speed of the propeller is divided into three balanced speeds of 1700r / min, 1800r / min, and 1900r / min. The corresponding engine speed ranges are [80%, 90%], [90%, 96%], and [96%, 100%], respectively. The default step values ​​are 540 steps, 760 steps, and 960 steps.

[0019] a) Propeller speed online calibration method:

[0020] 1) When the engine is in the ground running test state, the UAV operator pushes up the power lever to check the engine working condition. When the engine speed ng is in the range of [80%, 90%], the propeller speed should be between [1700±10]r / min. If it does not meet the requirements, the operator issues the "speed selection motor step increase" command once through the communication command, and then 5 steps are added to the default calibration position of 540 steps corresponding to the speed of [1700±10]r / min. If it still does not meet the requirements, the "speed selection motor step increase" command is issued once again, and the propeller speed is stabilized between [1700±10]. At this time, the UAV operator issues the "1700r / min calibration" communication command, and the actual running step number of the current speed selection stepper motor 550 steps replaces the default 540 steps and is stored in the electronic controller. In subsequent operations, 550 is used as the default step number corresponding to the speed of 1700r / min.

[0021] 2) When the engine speed is between [90%, 96%], the propeller speed should be between [1800±10]r / min. If it is lower than this range and does not meet the requirements, the operator sends the "speed selection motor step increase" command once through the communication command, and then 5 steps are added to the default calibration position of 760 steps corresponding to the speed of [1800±10]r / min. At this time, the propeller speed is stabilized between [2190, 2210] to meet the requirements. At this time, the UAV operator sends the "1800r / min calibration" communication command, and the actual running step number of the current speed selection stepper motor 765 replaces the default 760 steps and is stored in the controller. In subsequent operations, 765 is used as the default step number corresponding to the speed of 1800r / min.

[0022] 3) When the engine speed is between [96%, 100%], the propeller speed should be between [1900±10]r / min. If it is higher than this range and does not meet the requirements, the operator sends a "speed selection motor step reduction" command once through the communication command, and then the default calibration position corresponding to the speed of [1900±10]r / min is reduced by 5 steps. At this time, the propeller speed is stabilized between [1900±10]r / min and meets the requirements. At this time, the UAV operator sends a "1900r / min calibration" communication command, and the actual running steps of the current speed selection stepper motor 955 replace the default 960 steps and store them in the controller. In subsequent operations, 955 is used as the default step number corresponding to the speed of 1800r / min.

[0023] b) Automatic compensation rules for propeller speed:

[0024] 1) During flight, when the engine speed ng ≥ 96%, the speed selection step command CLA automatically selects 955 steps (calibrated value). When the power lever command PLA change rate is ≤ ±4° / s, the propeller speed ns is determined to be between [1900±10] r / min after a delay of 5s. If the propeller speed ns is collected and maintained at [1900, 1944] for more than 1s, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If the ns is collected and maintained at [1900, 1940] for more than 1s, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by 15 steps again, and so on. The maximum reduction in the number of steps of the stepper motor shall not exceed 105 steps;

[0025] 2) If the collected ns is maintained at [1940,1980] for more than 1s, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by 30 steps, and so on, and the maximum reduction does not exceed 105 steps;

[0026] 3) When the engine speed ng is between [90%, 96%], the speed selection step command CLA automatically selects 955 steps (calibrated value). When the power lever PLA command change rate is ≤±4° / s, after a delay of 5s, it is determined that the propeller speed ns should be between [1800±10]r / min. If the acquisition of ns≤1790r / min is maintained for more than 1s, the electronic controller automatically issues a command to control the stepper motor to increase the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If the acquisition of ns≤1790r / min is maintained for more than 1s, the electronic controller automatically issues a command to control the stepper motor to increase the number of steps by 15 steps again, and so on, until the speed meets the requirement of [1800±10]r / min. The maximum increase in the number of steps of the stepper motor shall not exceed 150 steps.

[0027] 4) When the engine speed ng is between [80%, 90%], the speed selection step command CLA automatically selects 550 steps. After a delay of 5s, it is determined that the propeller speed ns should be between [1700±10]r / min. If the propeller speed ns≥1710r / min is collected and maintained for more than 1s, the electronic controller automatically sends a command to control the stepper motor to reduce the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If the ns is collected and maintained for more than 1s at ns≥1710r / min, the electronic controller automatically sends a command to control the stepper motor to reduce the number of steps by 15 steps again, and so on, until the speed meets the requirement of [1700±10]r / min. The maximum reduction in the number of steps of the stepper motor shall not exceed 150 steps;

[0028] 5) When the engine speed ng is between [80%, 90%], the speed selection step command CLA selects 550 steps (calibrated value). After a delay of 5s, it is determined that ns should be between [1700±10]r / min. If the collected ns≤1690r / min is maintained for more than 1s, the electronic controller automatically sends a command to control the stepper motor to increase the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If the collected ns≤1690r / min is maintained for more than 1s, the electronic controller automatically sends a command to control the stepper motor to increase the number of steps by 15 steps again, and so on. The maximum increase in the number of steps of the stepper motor shall not exceed 100 steps.

[0029] 6) The electronic controller is powered on again, the current operation ends, and the number of speed selection step instructions returns to the calibrated state.

[0030] The method described in the present invention has been developed into a product, which has been tested separately and actually used on a certain type of turboprop engine. Ground tests and flight tests have been carried out with the turboprop engine, and it has been equipped in batches for users to use. The test and use results all show that the method is reasonable, feasible, and highly reliable, and has promotional significance. It can ensure that the same type of turboprop engine can accurately select the speed of the propeller within the full envelope.

Claims

1. A method for controlling the propeller speed of a turboprop engine for an unmanned aerial vehicle, characterized in that: The steps include: Under the ground running test state, the propeller speed of the UAV turboprop engine is calibrated to obtain the actual running steps of the speed-selecting stepper motor corresponding to the required different propeller speeds, and the steps are stored in the electronic controller as the default value; During the flight, the speed selection step command CLA automatically selects the default value of the number of steps. If the actual speed monitored does not meet the requirements, the propeller speed is controlled by the propeller speed automatic compensation law. The specific steps include: if the propeller speed is greater than the default value of the number of steps, the electronic controller automatically issues a command to control the number of steps of the stepper motor to decrease by a certain number of steps; if the propeller speed still does not meet the requirements, the electronic controller automatically issues a command to control the number of steps of the stepper motor to decrease by a certain number of steps again, and so on, until the stable range of the propeller speed meets the requirements; if the propeller speed is less than the default value of the number of steps, the electronic controller automatically issues a command to control the number of steps of the stepper motor to increase by a certain number of steps; if the propeller speed still does not meet the requirements, the electronic controller automatically issues a command to control the number of steps of the stepper motor to increase by a certain number of steps again, and so on, until the stable range of the propeller speed meets the requirements; The electronic controller is powered on again, the current operation ends, and the number of speed selection step instructions returns to the calibrated state.

2. The method for controlling the propeller speed of a turboprop engine for an unmanned aerial vehicle according to claim 1, characterized in that: In the ground running test state, the propeller speed of the UAV turboprop engine is calibrated to obtain the actual running steps of the current speed-selecting stepper motor, which is stored in the electronic controller as the default step number. The specific steps include: When the engine is in the ground running test state, the UAV operator pushes up the power lever to check the engine working condition. If the actual propeller speed is lower than the set speed range, it does not meet the requirements. The operator sends an "increase the number of steps of the speed selection motor" command once through the communication command, and then a number of steps are added to the running steps of the speed selection stepper motor at the default calibration position corresponding to the set speed range. At this time, the propeller speed will increase. If it still does not meet the requirements, the operator continues to send the "increase the number of steps of the speed selection motor" command, and the speed continues to increase until the propeller speed stabilizes within the set speed range; at this time, the UAV operator sends a write communication command to replace the default running steps of the speed selection stepper motor with the actual running steps of the current speed selection stepper motor and store it in the electronic controller. In subsequent operations, the updated actual running steps of the current speed selection stepper motor are used as the default value.

3. The method for controlling the propeller speed of a turboprop engine for an unmanned aerial vehicle according to claim 2, characterized in that: In the ground running test state, the propeller speed of the UAV turboprop engine is calibrated to obtain the actual running steps of the current speed-selecting stepper motor, which is stored in the electronic controller as the default step number. The specific steps include: When the engine is in the ground running test state, the UAV operator pushes up the power lever to check the engine working condition. When the engine speed ng is in the range of [86%, 96%], the propeller speed should be between [2000±10]r / min. If the actual propeller speed is lower than this range, it does not meet the requirements. The operator issues the "speed selection motor step increase" command once through the communication command, and 5 steps are added to the default calibration position of 720 steps corresponding to the speed of [2000±10]r / min. At this time, the propeller speed will increase slightly. If it still does not meet the requirements, the operator continues to issue the "speed selection motor step increase" command, and the speed continues to increase until the propeller speed stabilizes between [2000±10]r / min. At this time, the UAV operator issues the "2000r / min calibration" communication command, and the actual running step number X1 of the current speed selection stepper motor replaces the default 720 steps and is stored in the electronic controller. The updated X1 step number is used as the default value in subsequent operations.

4. The method for controlling the propeller speed of a turboprop engine for an unmanned aerial vehicle according to claim 2, characterized in that: In the ground running test state, the propeller speed of the UAV turboprop engine is calibrated to obtain the actual running steps of the current speed-selecting stepper motor, which is stored in the electronic controller as the default step number. The specific steps include: When the engine speed ng≥96%, the propeller speed should be between [2200±10]r / min. If the actual propeller speed is lower than this range, it does not meet the requirements. The operator sends the "speed selection motor step increase" command once through the communication command, and 5 steps are added to the default calibration position of 1080 steps corresponding to the [2200±10] speed. If it still does not meet the requirements, continue to send the "speed selection motor step increase" command, and the speed will continue to increase until the propeller speed stabilizes between [2200±10]r / min; at this time, the UAV operator sends the "2200r / min calibration" communication command, and the actual running step number X2 of the current speed selection stepper motor replaces the default 1080 steps and is stored in the controller. The updated X2 step number is used as the default value in subsequent operations.

5. The method for controlling the propeller speed of a turboprop engine for an unmanned aerial vehicle according to claim 1, characterized in that: The propeller speed automatic compensation rules include: during flight, when the engine speed ng ≥ 96%, the speed selection step command CLA automatically selects the default value of the number of steps, and when the power lever command PLA change rate is ≤ ± 4° / s, after a delay of 5s, it is determined that the propeller speed ns should be between [2200±10]r / min; if the propeller speed ns collected is greater than this range and is maintained within the range of [2210, 2244]r / min for more than 1s, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by 15 steps; after the adjustment is completed, the ns range is determined again after a delay of 5s. If the ns collected is still maintained within the range of [2210, 2244]r / min for more than 1s, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by 15 steps again, and so on, until the speed stability range meets the requirement of [2200±10]r / min, and the maximum automatic reduction in the number of steps of the stepper motor does not exceed 105 steps; If the collected ns is maintained at [2244,2288] for more than 1s, the electronic controller automatically issues a command to control the stepper motor to reduce the number of steps by 30 steps, and so on as mentioned above, until the speed stability range meets the requirement of [2200±10]r / min. The maximum automatic reduction in the number of steps of the stepper motor shall not exceed 105 steps.

6. The method for controlling the propeller speed of a turboprop engine for a UAV according to claim 1, characterized in that: The automatic compensation rules for propeller speed include: during flight, when the engine speed ng ≥ 96%, the speed selection step command CLA automatically selects the default step value; when the power lever PLA command change rate is ≤ ± 4° / s, the propeller speed ns is determined to be between [2200 ± 10] r / min after a delay of 5s; if ns ≤ 2190r / min is collected and maintained for more than 1s, the electronic controller automatically issues a command to control the stepper motor to increase the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If ns ≤ 2190r / min is collected and maintained for more than 1s, the electronic controller automatically issues a command to control the stepper motor to increase the number of steps by 15 steps again, and so on. The maximum increase in the number of steps of the stepper motor shall not exceed 150 steps.

7. The method for controlling the propeller speed of a turboprop engine for a UAV according to claim 1, characterized in that: The automatic compensation rules for propeller speed include: during flight, when the engine speed ng ≥ 86%, the speed stepping instruction CLA selects the default value of the number of steps, and after a delay of 5s, it is determined that ns should be between [2000±10]r / min. If ns≤1990r / min is collected and maintained for more than 1s, the electronic controller automatically sends a command to control the stepper motor to increase the number of steps by 15 steps. After the adjustment is completed, the ns range is determined again after a delay of 5s. If ns≤1990r / min is collected and maintained for more than 1s, the electronic controller automatically sends a command to control the stepper motor to increase the number of steps by 15 steps again, and so on. The maximum increase in the number of steps of the stepper motor shall not exceed 100 steps.

8. The method for controlling the propeller speed of a turboprop engine for an unmanned aerial vehicle according to claim 1, characterized in that: The propeller speed automatic compensation rule includes: during flight, when the engine speed is 94%≤ng≤96%, the speed selection step command CLA is maintained at the previous state after compensation.