468 results about "Rotor speed" patented technology

The invention discloses a motor control method and device, electronic equipment and a storage medium. The method comprises the following steps: acquiring a three-phase current, converting the three-phase current into a total current of a current period in a static coordinate system, and extracting a high-frequency current of the current period from the total current; extracting a rotor position and a rotor rotating speed from the high-frequency current; compensating the rotor rotating speed by using the expected rotating speed to obtain a quadrature-axis expected current; converting the total current into a quadrature-direct axis coordinate system, extracting a fundamental frequency current from the quadrature-direct axis coordinate system, compensating the fundamental frequency current by using a quadrature axis expected current and a direct axis bias current to obtain a first expected voltage, superposing the first expected voltage and a direct axis high-frequency voltage, and performing coordinate system conversion on a superposition result by using a rotor position to obtain a second expected voltage; obtaining a second expected voltage under the static coordinate system; and the three-phase current of the current period is controlled according to the second expected voltage to drive the motor, so that the motor has more obvious salient polarity through the direct-axis bias current, and vector control over the electrode is achieved.

The invention relates to a coaxial multi-rotor unmanned aerial vehicle control method based on a Koopman operator, and the method comprises the steps: constructing a deep neural network based on the Koopman operator, and mapping a state variable to a high-dimensional observable space through an encoder; in a high-dimensional observable space, state variables are predicted through a linear connection layer based on dimension rising state variables and rotor rotating speeds; the decoder restores the prediction result to an original state space; training a deep neural network by using historical flight data to obtain codec parameters and a weight of a linear connection layer, and constructing a linear dynamic model of the observation function and the unmanned aerial vehicle; and the prediction controller predicts state variables of future multiple steps of the unmanned aerial vehicle by using a linear dynamics model, and enables the unmanned aerial vehicle to track a given trajectory by minimizing a cost function to obtain optimal control input. Compared with the prior art, the method has the advantages that complete data-driven modeling is realized, and the method can adapt to unmanned aerial vehicles with different sizes, loads and flight conditions.

The invention relates to a non-inductive FOC open-loop to closed-loop switching method and device for an electronic water pump and a vehicle. The method comprises the steps that a rotor is pre-positioned; starting an open loop I-F; switching condition judgment; estimating the rotor speed based on an observer, calculating a normalization factor, and obtaining a mixed scale factor through cubic polynomial operation; acquiring an open-loop current instruction of a q axis and a closed-loop current instruction output by a closed-loop speed PI regulator; performing weighted synthesis on the two paths of current instructions according to the mixing scale factor to obtain a temporary target current instruction, and applying a change rate limit to obtain a final current instruction output in the current period; the original angle error of the observer estimation angle and the open-loop slope angle is calculated and normalized, the allowable adjustment step length and direction of the round are dynamically determined, and the angle correction amount of the round is generated and superposed to the open-loop slope angle to update the rotor angle reference value; and closed-loop switching is completed. According to the invention, the problems of electromagnetic torque impact and rotating speed fluctuation caused by instruction step change are solved.

The invention relates to a dynamic and static pressure mixed gas radial bearing, and belongs to the technical field of air bearings. The shaft sleeve is sleeved with the bearing seat, a limiting part is arranged outside the shaft sleeve, and a limiting groove is correspondingly formed in the inner wall of the bearing seat; in the radial direction, the bump foil assemblies are arranged between the shaft sleeve and the bearing seat, and in the circumferential direction, the bump foil assemblies are arranged between the limiting parts at intervals; a plurality of first air inlet holes are formed in the bottom of the limiting groove, a plurality of second air inlet holes are formed in the limiting part, and the first air inlet holes correspond to the second air inlet holes in position. According to the design, the integrity of the bump foil assembly can be guaranteed, the structure is simple, machining is convenient, and mounting and dismounting are more convenient. When the speed of the rotor is low, the static pressure gas forms a gas film, and the bearing capacity of the dynamic and static pressure mixed gas radial bearing is enhanced. When the rotating speed of the rotor is high, dynamic pressure can be generated on the basis of static pressure, and the dynamic pressure and static pressure mixed gas radial bearing has larger bearing capacity due to superposition of the dynamic pressure and the static pressure.

The disclosure relates to monitoring blades of a wind turbine rotor shaft. Example embodiments include a computer-implemented method of monitoring blades of a wind5 turbine (100), the wind turbine (100) having a plurality of blades (103a, 103b) mounted to a hub (102), each blade (103a) comprising one or more strain sensors (109a1-3) mounted to the blade (103a) at corresponding respective distances from the hub (102, 201) along the blade (103a), the method comprising: i) recording (1301) strain measurements from the strain sensors (109a1-3) on each of the plurality of blades10 (103a); ii) recording (1302) a rotor speed of the wind turbine (100); iii) calculating (1303) a statistical measure of each of the recorded strain measurements; iv) calculating (1304) a difference in the statistical measure for strain sensors at corresponding positions on each of the plurality of blades over a range of rotor speeds; and v) identifying (1305) the presence or absence of damage in one of the plurality of blades15 based on the calculated difference.

This disclosure pertains to the field of wind power technology and provides a method, system, equipment, and medium for calculating the velocity distribution of a wind turbine wake field. The method includes: acquiring wind speed, rotor speed, and airfoil aerodynamic data; constructing a prediction function for the wind turbine based on blade deformation data to output load distribution; inputting current blade deformation data to obtain the load distribution; calculating the blade spanwise circulation distribution based on relevant data; obtaining the intensity of wake vortices and shedding vortices based on the circulation distribution, thereby obtaining the wake control point position vector; and solving for the velocity distribution at any location within the downstream wake field of the wind turbine. This process aims to more accurately predict the relevant characteristics of the wind turbine wake field and solve the problem that existing wake field prediction models cannot consider the true shape of the wake. This method can consider the true shape of the wake to obtain an accurate wake field velocity distribution.

The invention belongs to the field of offshore wind power, and discloses a single-pile offshore wind turbine power regulation and load relief method, which comprises the following steps of: constructing a thrust system model of wind to a rotor and a tower; constructing a dual-mass transmission system model of the wind turbine generator; constructing a tower top front-back displacement model and a pile soil front-back displacement model; constructing a rotor speed tracking error model based on an adjustment error method; constructing a tracking error model of the change rate of the front-back displacement of the tower top; constructing an optimal control strategy based on an infinite vision field optimal cost function; and designing an optimal pitch control scheme based on a robust adaptive dynamic programming algorithm. According to the design of the RADP-based propeller pitch controller provided by the invention, the MOWT model does not need to be completely known, so that the calculation cost of the controller is reduced, and the calculation efficiency is improved.

The invention discloses a method, a system, a medium and equipment for evaluating a blade tip timing vibration displacement measurement error under a variable rotating speed. A blade end vibration displacement measurement value is generated based on an included angle between a blade end timing sensor and a rotating speed sensor, an included angle between a rotor blade root and a key phase reference on a rotating shaft, reference arrival time measured by a key phase sensor and a blade end rotating radius; a blade end timing vibration displacement measurement error mathematical model under the variable rotating speed is established, and a measurement error caused by the variable rotating speed is obtained based on the blade end vibration displacement measurement value; evaluating the maximum error of the blade tip timing vibration displacement measurement under the variable rotating speed, and obtaining the maximum error of the blade tip timing vibration displacement measurement under the variable rotating speed based on the measurement error; based on the measurement error and the blade end timing vibration displacement measurement maximum error under the variable rotation speed, the influence of the rotor rotation speed change speed and the blade initial angle position on the blade end timing vibration displacement measurement error is quantified.

The invention relates to a ship-borne unmanned aerial vehicle recycling method and system based on visual navigation and six-degree-of-freedom compensation. The method comprises the following steps: extracting infrared, polarization and fluorescence frequency domain features and fusing to obtain an anti-shielding composite descriptor; constructing a ship dynamics differential model, discretizing the ship dynamics differential model by adopting an explicit multi-step method, and predicting six-degree-of-freedom disturbance data of the ship; a vision and inertia combined cost function is constructed, a vision residual item is calculated, the continuity of the motion track of the unmanned aerial vehicle is restrained, and the optimized real-time pose of the unmanned aerial vehicle is obtained; decomposing the six-degree-of-freedom disturbance data into a body coordinate system compensation amount, setting a backstepping sliding mode control law containing feed-forward compensation, and generating an anti-disturbance trajectory instruction; and air data are collected in real time, the rotor rotating speed is corrected according to the air data, the electromagnetic adsorption force is calculated, and the ship-borne unmanned aerial vehicle is recycled. And the navigation stability under complex sea conditions is enhanced.

The invention relates to the technical field of aero-engine aerodynamic optimization and computer aided design, and discloses a response surface modeling-based aero-engine low-pressure turbine blade leading edge model numerical optimization design method and structure. According to the method, the wake injection angle is changed by adjusting the flow or the rotating speed of a rotor, accurate matching of Klebanoff stripes and large-scale vortex generation opportunities is achieved, stripe impact is promoted, and large-scale vortex fracture is accelerated; and meanwhile, by constructing a blade front edge modeling parameterization model and establishing a response surface agent model of a modeling design variable parameter combination and a boundary layer velocity mean square error, an optimal design variable parameter combination is determined in a constraint domain by taking maximization of the velocity mean square error in a boundary layer as a target. On the premise that the blade profile load is not changed, the momentum thickness and the total pressure loss of the boundary layer are effectively reduced, the design efficiency and the engineering applicability under the working condition of the low Reynolds number are improved, an additional flow control structure does not need to be introduced, and the structure is simple and easy to implement.

The invention relates to the technical field of unmanned aerial vehicle control, in particular to a physical-data hybrid fault diagnosis method and system for an electric vertical take-off and landing aircraft. The method comprises the following steps: firstly, selecting a proper flight state variable to construct an observer, and generating a residual signal between a rotor rotating speed estimation value and a tracking value; secondly, introducing a random forest to realize positioning isolation of rotor faults; a data set is constructed by integrating physical model data, a random forest classification model is trained, a physical-data hybrid diagnosis model is established, dynamic association between flight states and faults is captured, and multi-fault diagnosis of eVTOL under closed-loop control is realized.

A method for damping drivetrain vibrations of a wind turbine. The drivetrain has, at least, a rotor and a generator. The method includes receiving a first rotational speed signal at a first location along the drivetrain, the first rotational speed signal being a proxy for rotor speed of the rotor. The method also includes receiving a second rotational speed signal at a second location along the drivetrain, the second location being downwind from the first location, the second rotational speed signal being a proxy for generator speed of the generator. Further, the method includes determining a speed error based on a comparison of the first and second rotational speed signals. Moreover, the method includes determining a torque deviation signal for the wind turbine configured to dampen the drivetrain vibrations when the speed error exceeds a first speed threshold. In addition, the method includes applying the torque deviation signal to the generator to dampen the drivetrain vibrations.

The invention relates to the technical field of motor control, and discloses a sensorless direct-current brushless motor control system which comprises a motor modeling module, a state estimation module, a deep learning prediction module, a filtering fusion module, a self-adaptive control module and a control execution module. The invention also discloses a sensorless direct current brushless motor control method, which comprises the following steps of: model establishment: constructing an electrical model and a mechanical model for describing the dynamic behavior of the motor so as to obtain a motor operation dynamic model suitable for control calculation; and state estimation: performing preliminary estimation on the rotor position and the rotor speed of the motor by utilizing the running dynamic model and combining current and voltage real-time signals acquired in the running process of the motor. According to the method, high-precision and high-stability control of the motor under different load and operation conditions is realized through adaptive control and rotor state estimation optimization technologies, real-time dynamic adjustment and commutation accuracy of the motor are ensured, and the overall control performance is improved.

The invention aims to provide the clearance distance signal extraction and safety control method based on the laser radar, which is accurate in signal identification, clear in computational logic and efficient in closed loop control. The method comprises the following steps: a, fixing a laser radar system below a cabin of the wind driven generator; b, measuring the distance from the laser radar unit to a target point at the tail end of the blade by adopting a flight time principle; c, a data processing unit of the fan receives measurement data of the multiple laser radar units, an effective blade reflection signal is recognized through a signal aggregation statistical method, and the clearance distance between the blade and the tower is calculated according to the reflection signal; d, the clearance distance data between the blades and the tower is monitored in real time, and the optimal pitch angle adjustment amount is calculated through a fan control system in combination with the wind speed and rotor rotating speed parameters; and e, dynamically adjusting the pitch angle of the blade through a variable pitch execution mechanism of the fan. The method is applied to the technical field of laser radars.

The invention relates to the technical field of motor control, and discloses a vector control application of a direct drive motor, which comprises the following steps: S1, collecting stator current, rotor speed and bus voltage signals of the motor, and carrying out filtering preprocessing on the collected signals; and S2, constructing a self-adaptive flux linkage observation model, estimating a stator flux linkage in real time based on stator current and bus voltage signals in combination with rotor rotating speed information, and correcting stator resistance and inductance parameters through a model reference self-adaptive algorithm. According to the method, the motor parameters are corrected in real time through the self-adaptive flux linkage observation model, parameter drift caused by factors such as temperature change and magnetic saturation is effectively counteracted, and the accuracy of flux linkage estimation is improved; the improved PI regulator realizes online self-tuning of control parameters through a fuzzy control algorithm, can quickly adapt to changes of dynamic characteristics of the motor, and shortens the regulation response time of flux linkage and torque; and the resistance of the system to external interferences such as load fluctuation, power supply voltage change and the like is enhanced.

The magnetizing system comprises a tray, a positioning chuck, a tip cone piece and a magnetizing head, a magnetic induction unit is arranged in the magnetizing head, the rotor is driven by the positioning chuck to rotate, the tip cone piece abuts against the other end of the rotor, the system comprises a parameter initialization module, a magnetizing parameter database is loaded, and initial parameters are preset; the magnetizing simulation calculation module is used for obtaining pre-estimated parameters such as magnetizing time through finite element simulation based on the magnetic induction intensity; the magnetic uniformity detection module is used for monitoring and calculating the magnetizing uniformity in real time; and the parameter dynamic regulation and control module is used for regulating the rotating speed of the rotor according to the uniformity and regulating and controlling the magnetizing current through a temperature sensor and a mapping model. The problems that in the magnetizing process of an existing permanent magnet motor rotor, magnetizing uniformity is insufficient, a real-time monitoring and dynamic adjusting mechanism is lacked, and the magnetizing quality is unstable and positioning precision is poor due to the fact that the magnetizing quality is prone to being affected by temperature are solved.

The invention provides a rotor wing shielding compensation method for helicopter satellite communication, and relates to the technical field of helicopter communication methods, and the method comprises the following steps: collecting angular velocity data in real time through a rotor wing main shaft sensor, constructing a rotating speed state equation, and providing accurate input for phase prediction; predicting a rotor phase based on an extended Kalman filter; a dynamic time slot distribution function is designed, so that the communication time slot length is automatically adjusted along with the rotation speed change of the rotor; a non-linear phase error caused by rotor vibration is counteracted through a feed-forward compensation item; closed-loop time calibration of a communication protocol and a mechanical system is realized by adopting double PID controllers. According to the method, real-time closed-loop synchronization of a mechanical system and a communication protocol is realized by establishing a three-dimensional mapping relation of rotor rotating speed-phase-communication time slot, so that the problem of nonlinear error accumulation during dynamic change of the rotating speed is solved.

The invention relates to the field of motor control, and discloses a 100kW-level low-rotating-speed composite-structure energy-saving motor and a driving control method, and the method comprises the steps: firstly, detecting the rotor rotating speed, stator current, bearing temperature and vibration signals of the motor in real time through a sensor module; a data analysis module calculates change values of the rotating speed of the rotor in a plurality of continuous monitoring periods, accumulates the change values to obtain a comprehensive fluctuation ratio, and compares the comprehensive fluctuation ratio with a preset fluctuation ratio threshold interval; then, the current running state of the motor is judged according to a comparison result; the motor operation states comprise stable operation, overload operation and light load operation; finally, if the motor is in the stable operation state, the current driving parameters are maintained; if the motor is in the overload operation state or the light-load operation state, the current driving parameters are adjusted until the motor is in the stable operation state, and therefore the motor driving parameters are dynamically monitored and adjusted to maintain the motor in the stable state.

The invention discloses a brushless motor rotor angle determination method and device, equipment and a storage medium. The method comprises the following steps: synchronously acquiring original angle data of a Hall sensor, an incremental encoder and a back electromotive force observation module; respectively determining confidence coefficients of the Hall sensor, the incremental encoder and the back electromotive force observation module according to the rotating speed of the rotor, and performing weighted fusion on the original angle data of the Hall sensor, the incremental encoder and the back electromotive force observation module to obtain an initial fusion angle; based on the motor temperature, the motor phase current and the rotor speed, calculating a temperature drift compensation angle through a segmented temperature drift coupling model, and compensating the initial fusion angle according to the temperature drift compensation angle to obtain a temperature drift compensated angle; and inputting the temperature drift compensated angle into an extended Kalman filter for state estimation and filtering to obtain a rotor angle estimation value at the current moment. By means of the method, high-precision real-time calculation of the rotor angle within the wide temperature range and the full rotating speed range can be achieved.

The invention provides a continuous wave mud pulse code modulation method, device and equipment and a storage medium, and belongs to the technical field of oil and gas drilling. The method comprises the following steps: encoding detected target acquisition information into a multi-system code element; two code elements are taken as a group to form a code element group, and the code element group controls the rotating speed of a rotor together to form a modulated pressure wave signal for determining a phase delay degree and a phase switching position corresponding to the phase delay degree; wherein the phase switching position is a time period when the corresponding phase delay degree occurs in a modulation period of the code element group to the pressure wave signal. According to the invention, on the premise of not additionally occupying frequency band resources, the transmission information amount is doubled, so that the signal transmission rate based on the continuous wave mud pulse is doubled, and the defect of low transmission rate in the traditional code modulation mode for the continuous wave mud pulse is overcome.

The invention relates to the technical field of motor control, and particularly provides a permanent magnet synchronous motor sensorless control method and system, and the method comprises the steps: designing a linear state observer according to a stator voltage equation of a permanent magnet synchronous motor, and replacing an error linear term in the linear state observer with a nonlinear function containing an error term, a generalized nonlinear state observer is formed to accurately obtain the back electromotive force estimation value of the motor, a traditional orthogonal phase-locked loop is improved, a parallel phase-locked loop structure is adopted, the back electromotive force estimation values of a # imgabs0 # shaft and a # imgabs1 # shaft are subjected to parallel calculation, and rotor position estimation and rotor speed estimation are obtained. The generalized nonlinear state observer and the parallel-connected phase-locked loop structure are designed to replace a traditional second-order linear state observer and a cascaded orthogonal phase-locked loop structure, and the dynamic performance, the anti-interference performance and the rotor position estimation precision of the permanent magnet synchronous motor under complex working conditions are effectively improved.

A ride-on power trowel has first and second engines mounted to a rigid frame. Each of first and second drive loops have a hydraulic pump powered by such an engine and a drive motor powered by the hydraulic pump. Rotor assemblies are coupled to the drive motors and configured to contact a concrete surface beneath the frame. A feedback controller sets rotor speed in each assembly to a power limited speed based on loads sensed in the drive loops. The power limited speed is an estimated maximum rotor speed achievable for the highest sensed load, which may be affected by operating data received from the engine associated with the highest sensed load.

The invention belongs to the technical field of wind power control, and discloses a wind driven generator fixed time adaptive neural network variable pitch control method, which comprises the following steps: step 1, establishing a kinetic model of a wind driven generator, and initializing a system state and control parameters; 2, aiming at the wind driven generator system with external interference, designing a fixed time sliding mode surface based on a sliding mode thought; and step 3, designing a fixed-time adaptive neural network variable pitch controller. The method has the advantages that under the conditions that external interference exists in the wind driven generator and parameters are uncertain, rapid convergence of the rotor rotating speed tracking error within fixed time is achieved, and the convergence time does not depend on the initial state.

The invention discloses a position-sensorless heavy-load starting method for a permanent magnet synchronous motor. The method comprises the following steps: establishing a discrete current model of the permanent magnet synchronous motor in a two-phase static coordinate system under the excitation of a high-frequency square wave signal; injecting the six-pulse voltage into the permanent magnet synchronous motor based on a three-phase static coordinate system to carry out rotor magnetic pole identification so as to correct the initial electrical angle of the rotor, and further obtaining a rotor position error signal in combination with a discrete current model; a rotor position error signal is processed through an improved phase-locked loop control system based on model reference self-adaption, and then the finally estimated rotating speed and electrical angle of the rotor are obtained; and then inputting the signal as a feedback signal into a magnetic field orientation control system to realize position-sensorless closed-loop starting control of the permanent magnet synchronous motor under a heavy load condition. By means of the method, the reliability of the starting process and the stability of a control system can be remarkably improved, and therefore reliable position-free closed-loop control under the low-speed large-load working condition and even within the full-speed domain range is achieved.

The invention discloses a wind turbine generator multi-stage self-adaptive droop control method considering rotor kinetic energy constraint and frequency change rate, which comprises the following steps: 1, constructing a rotation speed influence factor based on a Logistic function, mapping a rotor rotation speed into a frequency modulation contribution coefficient, and quantitatively evaluating a rotor kinetic energy releasable range of a fan under different operation conditions; 2, designing a self-adaptive droop control strategy based on a segmented frequency change rate, adjusting a droop coefficient in real time by identifying a frequency change rate interval, forming a hierarchical response mechanism, providing strong active support in a sharp frequency drop stage to quickly suppress frequency drop, and converting into moderate support in a frequency recovery stage to maintain stability and prevent secondary drop; and 3, building a wind-fire combined system simulation model, and verifying the effectiveness of the provided strategy in the aspects of improving the frequency response characteristic of the system and improving the frequency stability through a multi-scene contrast experiment. According to the method, the frequency regulation capability of the power system under the high wind power permeability can be remarkably enhanced.

The invention provides a blade state monitoring method, device and system of a wind turbine generator. The blade state monitoring method of the wind turbine generator comprises the following steps: acquiring an impeller rotation video of the wind turbine generator; performing frame-by-frame image processing on the impeller rotation video to obtain a real-time clearance value of each blade in the impeller, and constructing clearance time sequence data of each blade by using the real-time clearance value of each blade; obtaining an unbalanced component sequence of each blade by using the clearance time sequence data of each blade and a preset clearance reference value; and determining the unbalance level of the impeller according to the unbalance component sequence of each blade and the rotating speed time sequence data of the impeller. According to the invention, the online real-time monitoring of the operation state of the wind turbine generator blade can be realized in a non-contact manner, the deployment is flexible, the precision is controllable, and the hardware cost is low.

A method for detecting and responding to a failure in a drivetrain of a wind turbine includes estimating a first rotational speed signal at a first location along the drivetrain via one or more rate gyroscopes mounted in a hub, the first rotational speed signal being a proxy for rotor speed of a rotor. The method also includes processing the first rotational speed signal to account for a bias in the first rotational speed signal due to use of the rate gyroscope(s). Further, the method includes receiving a second rotational speed signal at a second location along the drivetrain, the second location being downwind from the first location, the first and second locations being on opposing sides of a potential slip location of the drivetrain. Moreover, the method includes determining a speed error based on a comparison of the first and second rotational speed signals. In addition, the method includes comparing the speed error to a threshold and implementing a control action when the speed error exceeds the threshold.

The application discloses a kind of offshore wind turbine pitch control methods based on predefined time adaptive dynamic programming, comprising: establishing single-pile offshore wind power generator full coupling mathematical model;The single-pile offshore wind power generator full coupling mathematical model includes the motion equation of system and the mathematical model of double-mass transmission system;Using the mathematical model of double-mass transmission system constructs rotor speed tracking error, adopts error adjustment method to process the non-affine characteristic of system, obtains the nonlinear affine model of single-pile offshore wind power generation system in combination with motion equation;The control strategy is constructed as the infinite time domain optimal performance index function of the change of pitch angle;Using predefined time nonlinear disturbance estimator estimates disturbance term in nonlinear affine model;To the equivalent form of Hamilton-Jacobi-Bellman equation of infinite time domain optimal performance index function, the approximate optimal control method based on only evaluation type neural network is used to solve equation to obtain optimal control strategy.

The present application relates to the technical field of aero-engine aerodynamic optimization and computer-aided design, and discloses a numerical optimization design method and structure for aero-engine low-pressure turbine blade leading edge modeling based on response surface modeling. The method realizes precise matching of Klebanoff stripe and large-scale vortex generation timing by adjusting flow or rotor speed to change wake injection angle, and promotes stripe impact and accelerates large-scale vortex breakup. Meanwhile, by constructing a blade leading edge modeling parameterization model and establishing a response surface proxy model for the combination of modeling design variable parameters and boundary layer velocity mean square deviation, the optimal design variable parameter combination is determined in the constraint domain with the maximum velocity mean square deviation in the boundary layer as the target. The present application effectively reduces the boundary layer momentum thickness and total pressure loss under the premise of ensuring constant blade load, improves the design efficiency and engineering applicability under low Reynolds number conditions, and does not need to introduce additional flow control structures, thus being simple in structure and easy to implement.

The hot fluorine defrosting valve for the refrigerating unit comprises a valve body, a main pipe, a first branch pipe and a second branch pipe are arranged on the valve body, a connecting plate is fixedly connected to the top of the valve body, a servo motor is installed on the top of the connecting plate, a rotating shaft of the servo motor penetrates through the top of the valve body, and the rotating shaft of the servo motor is fixedly connected with the main pipe. The first branch pipe is fixedly connected with a valve element, a rotor is installed in the first branch pipe, and a Hall sensor and a temperature sensor are installed on the inner wall of the first branch pipe. According to the utility model, the microcontroller receives a temperature signal monitored by the temperature sensor, and precisely controls the servo motor to adjust the position of the valve core by combining with the rotating speed of the rotor detected by the Hall sensor, so that high-temperature and high-pressure hot fluorine enters the evaporator for defrosting, the Hall sensor ensures the stability of flow, and the temperature sensor monitors the temperature of a pipeline in real time; the microcontroller automatically controls the servo motor to adjust the state of the valve element according to sensor data and preset data.