Portable ground controller for micro turbojet engines

Abstract

This invention relates to the field of gas turbine start-up control technology and discloses a portable ground controller for a micro turbojet engine, comprising: an exhaust temperature detection unit, a rotor speed sensing unit, a current monitoring unit, and a control processor. The control processor uses a stored thermal response time constant to perform differential feedforward compensation on the original temperature signal, calculates the thermodynamic characteristic quantity reflecting the transient thermal evolution at the combustion chamber outlet, and extracts the friction loss term from the rotor angular acceleration based on the cold rotation current intensity to generate a dynamic characteristic quantity. It then monitors the phase offset of the thermodynamic characteristic quantity relative to the dynamic characteristic quantity in real time, and outputs a fuel shut-off command when the offset exceeds a safety deviation threshold. This invention eliminates sensor thermal response hysteresis, achieves synchronous alignment of internal energy release and rotor kinetic energy growth on the physical time axis, solves the perception parallax problem in the start-up transient process, and can accurately identify the thermal accumulation evolution and execute protective actions.

Description

Technical Field

[0001] This invention relates to a portable ground controller for a micro turbojet engine, belonging to the field of gas turbine start-up control technology. Background Technology

[0002] Currently, gas turbine units, especially micro turbojet engines, are widely used in unmanned aviation and portable power fields. They use a preset fuel speed mapping table in conjunction with exhaust temperature feedback to regulate fuel flow. In portable field applications, atmospheric density and fuel viscosity fluctuate drastically with altitude or ambient temperature, making it difficult for static control data to adapt to the changing physical conditions. The rotational inertia of the micro turbojet engine rotor is extremely small, but the exhaust temperature sensor has thermal inertia due to the heat capacity of the metal casing, which makes it impossible to capture the transient heat flux density at the combustion chamber outlet in real time. This lag in perception makes it difficult for the control logic to synchronize the release of thermal energy and the increase of kinetic energy on the physical time axis during the start-up transient process.

[0003] To cope with environmental changes, the industry often tries to add physical atmospheric pressure gauges or infrared thermometer arrays, which increases the weight and cost of portable systems and introduces additional hardware failure points. Simple threshold judgment or proportional adjustment cannot eliminate the phase misalignment caused by sensing inertia, causing the system to miss the optimal pulse interception window when approaching the thermal surge limit due to criterion lag. The controller integration process faces the constraints of lightweight hardware layout, and there are also bottlenecks in the control accuracy and anti-interference capability at the software algorithm level. For example, Chinese invention patent CN114687867B discloses a micro turbojet engine controller and starting control method, which realizes automated management of the starting process through a distributed architecture. The core logic is based on a fixed temperature rise threshold and a linear acceleration slope. Such technology fails to dynamically compensate for the thermodynamic delay of the sensor and lacks an integrated decoupling mechanism for mechanical friction loss and atmospheric environmental fluctuations. This makes it impossible for the system to accurately identify the thermal accumulation evolution in the early stage of starting under extreme deployment environments. It is easy to miss the optimal pulse interception window due to the mismatch of the feedback criterion time axis, resulting in overheating ablation or starting failure.

[0004] Therefore, the technical problem to be solved by this invention is how to overcome the perceptual parallax caused by perceptual inertia without introducing external sensors, and to achieve endogenous compensation for atmospheric environmental fluctuations. Summary of the Invention

[0005] To address the problems mentioned in the background art, the technical solution of the present invention is as follows: A portable ground controller for a micro turbojet engine, comprising an exhaust temperature detection unit, a rotor speed sensing unit, a current monitoring unit, and a control processor:

[0006] The control processor is electrically connected to the exhaust temperature detection unit, the rotor speed sensing unit, and the current monitoring unit, respectively; the control processor stores the thermal response time constant characterizing the physical heat capacity of the exhaust temperature detection unit.

[0007] The control processor performs the following operations: based on the raw temperature signal collected by the exhaust temperature detection unit and the thermal response time constant, it calculates the thermodynamic characteristic quantity reflecting the transient temperature evolution trend of the combustion chamber outlet airflow through differential feedforward compensation.

[0008] The rotor angular acceleration is calculated based on the real-time rotational speed collected by the rotor speed sensing unit, and a resistance mapping model that fluctuates with the current ambient temperature is established based on the cold rotation current intensity obtained by the current monitoring unit during the cold rotation stage before engine ignition.

[0009] By subtracting the bearing friction torque loss term from the rotor angular acceleration using a resistance mapping model, dynamic characteristic quantities reflecting the effective work capacity of the rotor are generated.

[0010] Real-time monitoring of the phase shift of thermodynamic characteristics relative to dynamic characteristics, and identification of the transient matching degree between the combustion chamber outlet internal energy release rate and the rotor kinetic energy growth rate based on the phase shift.

[0011] When the phase offset exceeds the preset safety deviation threshold, a fuel shut-off command is output to the fuel system actuator to perform a protective action during the initial thermal buildup evolution stage of startup.

[0012] Preferably, the logic for controlling the processor to calculate thermal characteristic quantities includes: acquiring the rate of change of the original temperature signal over time in real time; multiplying the rate of change by the thermal response time constant to obtain a compensation correction value; and summing the compensation correction value with the original temperature signal to offset the sensing lag caused by the heat capacity of the exhaust temperature detection unit.

[0013] Preferably, the logic for controlling the processor to generate dynamic characteristic quantities includes: determining the basic friction load of the engine under the current environment based on the cold rotation current intensity, and using it as the zero-point reference of the resistance mapping model; during the engine start-up and acceleration phase, determining the dynamic friction torque at the corresponding speed through the resistance mapping model, and subtracting the acceleration component corresponding to the dynamic friction torque from the rotor angular acceleration.

[0014] Preferably, the signal sampling frequency of the control processor is set to be no less than 100Hz, and the control processor triggers a fuel shut-off command when the growth slope of the thermodynamic characteristic quantity deviates positively from the growth slope of the power characteristic quantity.

[0015] Preferably, the system also includes an integrated control housing, with the control processor fixed inside the integrated control housing, and the outside of the integrated control housing is provided with an aviation electrical connector for interfacing with the external wiring harness of the micro turbojet engine.

[0016] Preferably, the control processor dynamically calculates the safety deviation threshold based on the preset operating condition envelope, and when the phase offset exceeds the safety deviation threshold for a duration of 50ms, the control processor outputs a fuel shut-off command.

[0017] Preferably, the real-time calculation of thermal characteristic quantities follows the following formula: ,in, It is a thermodynamic characteristic quantity. This represents the temperature value corresponding to the original temperature signal. The thermal response time constant is expressed in seconds. The rate of change of temperature over time, in units of / s.

[0018] Preferably, the control processor also stores a sensor aging correction factor determined based on the engine's historical starting cycle count, and the control processor performs online numerical correction of the thermal response time constant based on the sensor aging correction factor.

[0019] Preferably, if the control processor detects that the power characteristic quantity does not produce a positive step of a preset amplitude within a preset time after the ignition pulse is emitted, it determines that the start-up has failed and forcibly executes the fuel shut-off command.

[0020] Preferably, the control processor monitors the system bus voltage in real time through the current monitoring unit, and executes power drop protection logic by reducing the judgment weight of the power characteristic quantity when the bus voltage is lower than 10V.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. In a micro turbojet engine, by introducing a sensing inertial compensation mechanism in the coupled calculation of angular acceleration and exhaust temperature change rate, the thermal response lag caused by the physical heat capacity of the thermocouple measurement end is eliminated. This enables the thermodynamic operator characterizing the release of combustion internal energy and the dynamic operator characterizing the growth of rotor kinetic energy to be synchronously aligned on the physical time axis. This solves the sensing parallax problem in the transient process of micro turbojet engine startup and ensures that the fuel supply pulse interception action can be accurately applied to the initial stage of thermal accumulation evolution.

[0023] 2. By utilizing the current feedback and speed characteristics of the starter motor at different operating stages, a mechanical loss detection path independent of the thermodynamic cycle is constructed. This eliminates the interference caused by the fluctuation of bearing friction torque with ambient temperature and service life, ensuring that the determination of the starting thermal efficiency factor is controlled only by the aerodynamic thermodynamic state in the combustion chamber. This avoids the logic overcompensation phenomenon caused by hardware aging or lubrication characteristic deviation, and improves the stability of the controller for the engine's health status throughout its entire life cycle.

[0024] 3. By combining the quasi-steady-state speed feedback during the cold start phase before ignition, the driving process of the starter motor is reused as an atmospheric density sensing unit. Through the physical causal chain between the compressor aerodynamic resistance and the ambient air pressure, the dynamic migration of the start-up safety window boundary value is realized. This allows the propulsion device to autonomously correct the fuel supply trajectory according to the real-time altitude conditions without relying on external air pressure compensation hardware, thus eliminating the calibration redundancy of the portable system when deployed across regions. Attached Figure Description

[0025] Figure 1 This is a flowchart of the control logic based on thermal response compensation and phase alignment of the present invention.

[0026] Figure 2 This is a schematic diagram of the hardware architecture and functional principle of the control processor of the system of the present invention. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] This invention provides a portable ground controller for a micro turbojet engine, comprising an exhaust temperature detection unit, a rotor speed sensing unit, a current monitoring unit, and a control processor. The control processor is electrically connected to the exhaust temperature detection unit, the rotor speed sensing unit, and the current monitoring unit, respectively. The control processor stores a thermal response time constant characterizing the physical properties of the exhaust temperature detection unit. The exhaust temperature detection unit is used to acquire the engine's real-time exhaust temperature and convert it into a raw temperature signal. The rotor speed sensing unit is used to acquire the rotor rotation frequency and convert it into real-time speed. The current monitoring unit is used to acquire the real-time drive current of the starter motor. The control processor is used to determine the thermal response time constant. For the original temperature signal By performing differential feedforward compensation, thermodynamic characteristic quantities reflecting the transient temperature evolution at the combustion chamber outlet are obtained. The control processor is used to determine the real-time drive current. Rotor angular acceleration The friction loss term is removed from the middle section to generate dynamic characteristic quantities; the control processor is used to monitor the thermodynamic characteristic quantities. The phase offset relative to the power characteristic quantity is used to output a fuel cut-off command when the phase offset exceeds the safety deviation threshold; to address the issue of parallax in the physical time axis caused by the sensing lag of the exhaust temperature sensor due to the heat capacity of the metal casing, which leads to the relationship between heat release and kinetic energy growth, the control processor processes the raw temperature signal... Perform phase advance compensation; obtain the preset thermal response time constant. And based on real-time temperature measurements First-order differential term with time and thermal response time constant The product of the original temperature signal Perform feedforward gain compensation; thermodynamic characteristic quantities Real-time calculations follow the formula below: ,in, It is a thermodynamic characteristic quantity. The original temperature signal The corresponding real-time temperature measurement value, The thermal response time constant is expressed in units of 1000 kJ / m². , To measure the rate of change of temperature over time, the unit is... For example, when the system sampling frequency is set to 100Hz, if at the current time... It is 450.5 The previous value was 448.2. Then the calculation yields 230 If the thermal response time constant It is 0.3 The calculated thermodynamic characteristic quantity It is 519.5 This calculation process restores the measured values ​​to characteristic operators reflecting the transient heat flow at the combustion chamber outlet, and synchronizes them with dynamic characteristic quantities through sampling. This enables the calculation of the starting thermal efficiency factor while eliminating sensor physical hysteresis interference. .

[0029] To eliminate the interference of bearing frictional resistance fluctuations with ambient temperature on the starting criteria, the real-time drive current of the starter motor is used. A drag mapping model is established to isolate non-combustion power consumption; during the cold start phase before the engine executes the ignition sequence, the control processor obtains the real-time drive current of the starter motor under constant power through the current monitoring unit. Since motor torque is directly proportional to current intensity, real-time speed is established. With real-time drive current The characteristic mapping curve is used, with the current intensity obtained during the cold rotation stage as the basic friction load and as the zero-point reference of the resistance mapping model; during the engine start-up and acceleration stage, the dynamic friction torque at the corresponding speed is determined through the resistance mapping model, and the rotor angular acceleration is used as the reference. Subtract the frictional load offset corresponding to the dynamic frictional torque from the middle. This generates dynamic characteristic quantities that reflect the effective work capacity of the rotor; the procedure eliminates the resistance torque deviation caused by lubricating oil viscosity or bearing wear, thus improving the starting thermal efficiency factor. The determination is controlled by the aerodynamic and thermodynamic state within the combustion chamber; based on the fact that changes in atmospheric density alter the compressor's aerodynamic drag when the portable controller is deployed at different altitudes, the quasi-steady-state speed before ignition is utilized. Correct the safety deviation threshold; during the preheating phase before the ignition command is executed, control the processor to obtain the quasi-steady-state speed of the engine under constant starting power. Since the air resistance experienced by the rotor is proportional to the ambient density, the control processor determines the quasi-steady-state rotational speed. The boundary value of the high and low linear adjustment safety deviation threshold is used to compensate for the influence of atmospheric density on the compressor aerodynamic load; when the quasi-steady-state speed... When operating at higher RPMs, the ambient air density is lower, and the system adjusts its safety deviation threshold to compensate for the thermal stress damage caused by decreased cooling efficiency at high altitudes. To suppress combustion chamber pressure pulsations and system resonance caused by discrete fuel injection, the control processor adjusts the real-time RPM... Extract the rotational speed ripple component; control the processor to adjust the rotor angular acceleration. Perform high-frequency sampling to filter out rotor angular acceleration. The DC component is preserved, and the minute frequency oscillation component caused by the aerodynamic load fluctuation of the blades is retained. Spectral analysis is then performed on this component to identify the characteristic frequency of the fluctuation. When the frequency of the fuel supply pulse signal Entering the wave characteristic frequency Within the preset bandwidth, the frequency is adjusted by changing the pulse width of the duty cycle. Shift to fluctuation characteristic frequency Outside the range of influence, this operation interrupted the evolution frequency of the airflow velocity cluster, thereby achieving the regulation of the inlet flow field.

[0030] To achieve thermodynamic characteristic quantities under a unified spatiotemporal reference The phase offset of the dynamic characteristic quantities is quantized and compared, and the control processor executes the heterogeneous signal time reference alignment procedure; the control processor opens a signal smoothing buffer with a length of 50ms to obtain the phase-compensated thermodynamic characteristic quantities. The real-time sequence and the real-time sequence of dynamic characteristics after loss stripping are obtained; since the rotor dynamic response and thermodynamic response have different time constants, a first-order hysteresis mapping is performed on the dynamic characteristics within the signal smoothing buffer to simulate the energy release trend of the combustion chamber outlet in the time domain; the phase offset is calculated according to the following formula: ,in, Phase offset, in units of , This is a thermodynamic characteristic quantity, with units of . , For dynamic characteristic quantities, the unit is . , This is the mapping coefficient from kinetic to thermodynamic, with a value of 0.4. , Current real-time speed The corresponding quasi-steady-state exhaust temperature reference value is given below, in units of This mechanism characterizes the degree of energy mismatch during engine start-up. The system connects to the external wiring harness of the micro turbojet engine via an aviation electrical connector on the outside of the integrated control box. If the power characteristic quantity does not produce a positive step of a preset amplitude within a preset time after the ignition pulse is detected, the control processor determines that the start-up has failed and outputs a fuel shut-off command. The current monitoring unit monitors the system bus voltage in real time, and when the bus voltage is below 10V, the power drop protection logic is executed by reducing the judgment weight of the power characteristic quantity.

[0031] The physical essence of the sensor aging correction factor is to characterize the surface evolution of the alloy cladding in the exhaust temperature detection unit under long-term high-temperature thermal cycling. As the cumulative number of engine start cycles increases, a layer of oxide scale and carbon deposits with a thickness ranging from 0.02mm to 0.08mm will physically form on the probe surface. The thermal conductivity of this coating layer is much lower than that of the metal substrate, resulting in a physical increase in the effective heat capacity of the temperature sensing end. The correction process is not a simple numerical scaling, but based on the material evolution trend. Whenever the historical number of start cycles reaches 500 steps, the system automatically adjusts the thermal response time constant. The physical reference value is compensated upwards by 8% to 12% to offset the thermal conduction hysteresis caused by the thickening of the oxide layer. During the commissioning procedure, this system supports manual input of the probe's measured diameter increment via the calibration interface. If the probe's outer diameter increases by more than 0.1mm from the original specification due to carbon buildup, the control processor will forcibly trigger a sensor maintenance warning and lock the correction factor to the safe upper limit to ensure that the differential feedforward compensation logic does not produce sensing distortion due to material aging. The dynamic calculation of the operating condition envelope is achieved by reusing the starter motor as a virtual atmospheric density meter. During the start-up preheating stage, the control processor drives the starter motor to operate at a fixed 15% pulse width duty cycle. At this time, the aerodynamic resistance of the compressor blades affects the quasi-steady-state speed. The only physical variable, under high-altitude conditions at 4500m, is the reduced blade rotational damping due to the thin air, resulting in a decrease in the measured rotational speed. The speed will be physically increased by about 2500 rpm compared to the sea level standard value. The dynamic tightening logic of the safety deviation threshold is essentially a physical transfer of the thermal stress protection margin. Due to the significant decrease in the mass flow rate of cooling air entering the turbine at high altitudes, the system physically narrows the matching deviation range between thermal and power (from 80℃ to 55℃) to shut off the fuel regulating valve in advance before the turbine blades undergo physical melting and deformation. During the commissioning procedure, the operator needs to perform a zero-position cold rotation at the initial deployment location using the calibration knob on the control box panel. The system will record the maximum cold rotation resistance torque under the current environment as the physical zero-point reference for all subsequent judgments.

[0032] Example 1: At an altitude of 4500m and an ambient temperature of -15°C Under high-altitude field conditions, the micro turbojet engine executes the starting procedure. Due to physical constraints such as the ambient air density being lower than the sea-level standard value and the increased viscosity of the bearing lubricating oil due to low temperature, the starter motor drives the rotor into the cold-running stage, and the current monitoring unit obtains the real-time drive current. The current value is maintained in the range of 12A to 15A as the rotor overcomes viscous resistance. The control processor then uses the acquired real-time drive current... With real-time speed The corresponding relationship is used to determine the frictional load offset at the current rotational speed. 150 During the preheating phase before ignition, the control processor monitors the quasi-steady-state speed achieved under constant drive power. 12000 Corresponding to the current ambient air density, the control processor adjusts the safety deviation threshold from 80 under standard operating conditions. Adjusted to 45 During the millisecond-level evolution process after the ignition command is executed, the fuel-air mixture in the combustion chamber ignites, and the exhaust temperature detection unit feeds back the original temperature signal. Initial measurement temperature The sensing lag is caused by the heat capacity of the metal casing of the exhaust temperature detection unit, and the control processor calls the stored thermal response time constant. For the original temperature signal The calculation process for feedforward gain compensation follows the formula below: ,in, This is a thermodynamic characteristic quantity, with units of . , The original temperature signal The corresponding real-time temperature measurement value, in units of , The thermal response time constant is 0.3. , To measure the rate of change of temperature over time, the unit is... .

[0033] At a sampling frequency of 100Hz, if two adjacent sampling periods are within The incremental determination of the temperature change rate is 180. The calculated thermodynamic characteristic quantity Reaching 480 This value eliminates the interference of sensor physical inertia on signal phase, enabling the thermodynamic parameters to synchronize with the rotor dynamic response on the physical time axis; the control processor calculates the real-time rotational speed in real time. The second derivative is used to obtain the rotor angular acceleration. And subtract the frictional load bias generated by the resistance mapping model from it. This generates dynamic characteristic quantities that reflect the effective work capacity of the rotor, which, along with phase-compensated thermodynamic characteristic quantities... Common input start-up thermal efficiency factor The judgment logic is as follows: when the system detects a thermodynamic characteristic quantity... The temperature rise gradient and the growth gradient of the dynamic characteristic quantity show a mismatch, and the thermodynamic characteristic quantity The phase offset relative to the dynamic characteristic quantity exceeds 45 When the safety deviation threshold is reached, the control processor controls the temperature rise within 150°C before the thermal buildup evolves to the over-temperature limit. The internal reduction of the solenoid valve's opening duty cycle completes the interception and regulation of the oil supply pulse signal; during this process, the rotor angular acceleration is adjusted. By performing high-frequency sampling and filtering out the DC component, the characteristic frequency of pressure pulsation in the inlet flow field is identified. The frequency of the fuel supply pulse signal is 45Hz. By fine-tuning the width of the fuel supply pulse, the frequency of the fuel supply pulse signal is adjusted. Shifting to 60Hz avoids the resonance range of the system's inherent frequency, and the engine rotor, after being adjusted by the fuel supply pulse, crosses 30,000... The high-risk range for thermal buildup occurs when the peak exhaust temperature remains stable at 680°C. Within the safe range, as the rotor speed continues to increase, the dynamic characteristic quantity generates a positive step and enters a quasi-steady-state operation mode.

[0034] Example 2: In a starting test of a miniature turbojet engine simulating low outdoor temperatures and accompanied by broadband electromagnetic noise interference, the test system used a measurement resolution of 0.1. Thermocouple sensors and Hall effect tachometers with a sampling frequency of 1000Hz were used in this experiment to obtain data restoration parameters under non-ideal operating conditions. Gaussian white noise with a signal-to-noise ratio of 20dB was superimposed to simulate the 5% random amplitude disturbance of the speed signal caused by the magnetic field fluctuations generated by the commutation of the starter motor. The sampling frequency of the start-up test was set to 100Hz. This parameter was determined by balancing the computational load of the microcontroller with the fidelity of the signal reconstruction. Since the main frequency band of the exhaust temperature is below 5Hz, 100Hz was determined as the sampling step size under this condition based on the sampling theorem and with a 20-fold oversampling margin reserved to cooperate with the differential feedforward compensation algorithm. During the testing of the sample group of this invention, the ambient temperature was maintained at -10°C. The real-time drive current obtained by the starter motor during the cold start phase before engine ignition. The value is 14.2A. The control processor determines the angular acceleration bias caused by mechanical losses under the current operating condition through a drag mapping model. It is 135.5 .

[0035] The data conversion records during the start-up process are shown in Table 1. Table 1 shows the heterogeneous signal operatorization process of the sample group of this invention within the 500ms interval before ignition start-up, by reading the original temperature signal. And apply the thermal response time constant With a feedforward gain compensation of 0.3s, the thermodynamic characteristic quantity reflecting the transient thermal evolution at the combustion chamber outlet was calculated. Synchronously acquire real-time rotational speed And calculate the rotor angular acceleration. Subtracting angular acceleration bias The dynamic characteristic quantity is then generated, which in turn is derived from the thermodynamic characteristic quantity. The starting thermal efficiency factor is determined by the ratio of the derivative over time to the dynamic characteristic quantity. ; in time At any time, measure the temperature Only 460.3 The thermal characteristics reconstructed by the algorithm Reached 525.8 At this time, the thermal efficiency factor is activated. The value climbed from 1.12 to 1.85. Since this value exceeded the preset safety envelope limit of 1.5, the control processor... The system continuously outputs commands to adjust the width of the fuel supply pulses, reducing the total fuel supply by 20% and limiting the subsequent heat accumulation slope within a preset safety window. In contrast, the control group, which did not employ this method, suffers from a lag in the physical response of the exhaust temperature sensor. At that moment, its criteria were still in the safe zone, leading to... The time was 820.5. The data showed that the peak temperature was above the threshold temperature, and the comparative data confirmed the effectiveness of the sensing inertial cancellation mechanism in predicting the pulse interception window.

[0036] Table 1: Processing of heterogeneous signals as operators in the sample group of this invention within the 500ms interval before ignition.

[0037]

[0038] To determine the physical boundaries of key parameter ranges, the stripping effect under different lubricant viscosity gradients was tested. The real-time drive current measured during the cold start phase was also examined. When the value is below the lower limit of 5A, the accuracy of extracting dynamic characteristic quantities decreases by 30% because the bearing friction term and the aerodynamic drag term overlap in magnitude, resulting in a decrease in the starting thermal efficiency factor. The volatility rose to 0.25, making it unable to reliably identify abnormal heat buildup in the combustion chamber; and when the real-time drive current... When the value exceeds the upper limit of 25A, the rotor system exhibits nonlinear characteristics indicating the entry into the boundary friction state. At this point, the angular acceleration bias generated by the drag mapping model... A saturation effect occurs, and further increasing the compensation amount cannot further reduce the phase offset; instead, it increases the static processing delay of the control processor. Gradient comparison data reveals that in the real-time drive current... Within the operating window of 10A to 20A, the system maintains an accuracy rate of approximately 98.5% in identifying startup ablation risks, and the thermal characteristic values... The phase compensation residual stabilizes within 15ms; after the start-up test, the dynamic characteristic quantity is within the real-time speed range. A positive slope step is generated when the engine reaches 35,000 rpm, indicating that the engine is switching from starter motor-assisted drive to self-sustaining operation. The system then adjusts the speed based on the measured quasi-steady-state speed. The dynamic correction of safety deviation thresholds has enabled coverage of low-density working conditions at altitudes up to 4500m.

[0039] Example 3: This example combines Figures 1 to 2 A portable ground controller for a micro turbojet engine is described, such as... Figure 1As shown, basic physical parameters are acquired through multiple parallel channels. The exhaust temperature detection unit is responsible for acquiring the raw temperature signal. This signal is processed by the differential feedforward compensation module, which uses the thermal response time constant for correction, to calculate the thermodynamic characteristic quantity reflecting the transient thermal evolution of the combustion chamber outlet. At the same time, the rotor speed sensing unit acquires the real-time speed and performs rotor angular acceleration calculation based on the real-time speed derivative. The current monitoring unit acquires the cold rotation current intensity and establishes a benchmark based on the cold rotation current to construct a resistance mapping model. The logic flow converges to the friction loss stripping stage, where the resistance mapping model is used to generate the dynamic characteristic quantity reflecting the effective work capacity of the rotor. Then, the system enters the phase offset monitoring stage. By comparing the thermodynamic characteristic quantity and the dynamic characteristic quantity, the matching degree of internal energy release and kinetic energy growth is identified, and it is further determined whether the offset is greater than the safety deviation threshold to determine whether heat accumulation has occurred. If the determination result confirms that heat accumulation has occurred, a fuel shut-off command is output to execute the protection action.

[0040] like Figure 2 As shown, the hardware architecture of this system mainly consists of a micro turbojet engine and a portable ground controller that serves as an integrated control box. The two communicate and connect via an aviation electrical connector. The micro turbojet engine integrates an exhaust temperature detection unit with a metal-clad thermocouple, a rotor speed sensing unit with Hall effect and magnetoelectric sensors that also serves as a drag load detector, a starter motor, and a fuel system actuator containing a solenoid valve and a fuel pump. The portable ground controller is equipped with a current monitoring unit connected to a portable power supply and busbar to monitor busbar voltage and drive current. It also includes a control processor (MCU / DSP) as the core computing unit, which integrates multiple functional modules: first, post-thermal response compensation logic, which stores the thermal response time constant; second, dynamic characteristic stripping logic containing a drag mapping model; third, phase offset and safety threshold monitoring logic integrating sensor aging correction factors; and finally, a fuel shut-off command generation module.

[0041] Example 4: When the system faces the initial state differences of the starter motor overcoming the viscous resistance of lubricating oil under different ambient temperatures, the control processor executes the parameter initialization procedure of the resistance mapping model; during the 2-second cold start period before the engine enters the ignition sequence, the control processor issues a power drive command with a constant duty cycle of 15% to the starter motor and monitors the real-time speed. The growth slope is calculated, and when the rotational speed fluctuation rate is below 0.5% for five consecutive sampling periods, the rotor is determined to have reached a quasi-steady state. At this point, the current monitoring unit collects the real-time drive current. The current is 15.2A; the control processor utilizes the pre-stored torque current coefficient to adjust the real-time drive current. Convert to current frictional load bias Frictional load bias The calculation follows the formula: ,in, This represents the frictional load bias, in units of... , The preset torque conversion operator has a value of 10.5. , The current is the real-time drive current of the starter motor, in amperes (A); the frictional load offset is calculated under this operating condition. It is 159.6 This value was used as the rotor angular velocity during the subsequent acceleration phase. The zero-point subtraction benchmark eliminates dynamic measurement errors caused by the temperature drift of lubricating oil properties; to address the atmospheric density compensation requirements under different altitude deployment scenarios, the control processor obtains the quasi-steady-state rotational speed during the preheating stage. Dynamically reconstruct safety deviation threshold To eliminate the influence of compressor aerodynamic load variations on the starting criteria; it internally stores reference speeds under standard sea-level operating conditions. For 10000 and the corresponding initial threshold For 80 Corrected safety deviation threshold Determined according to the following linear mapping method: ,in, This represents the safety deviation threshold under the current operating conditions, in units of... , The initial safety deviation threshold under standard operating conditions is set to 80. , The measured quasi-steady-state speed under constant starting power, in units of , The standard reference speed is set to 10000. , This is the density compensation coefficient, with a value of 0.01. If the measured quasi-steady-state speed 12500 At that time, the current safety deviation threshold is calculated. 55 Through this calibration procedure, the system actively tightens the determination boundary of phase offset under high-altitude operating conditions, thus offsetting the decreasing trend of turbine cooling capacity caused by thin air.

[0042] During startup and acceleration, in order to perform spectrum offset optimization to avoid the resonance risk caused by discrete pulse oil supply, the control processor adjusts the rotor angular acceleration after deducting friction losses. Perform a 512-point Fast Fourier Transform (FFT) operation based on a Hamming window; acquire raw speed data from the rotor speed sensing unit at a frequency of 1000Hz, and extract rotor angular acceleration within a sliding window consisting of 512 data samples. The pulsating residual components are calculated, and the power spectral density is used to identify the pulsation characteristic frequency corresponding to the point of maximum amplitude. When the frequency of the oil supply pulse signal output by the system With fluctuation characteristic frequency When the absolute value of the difference is less than 5Hz, the control processor, while keeping the total fuel injection duration constant, injects a pseudo-random time jitter amount that follows a uniform distribution into the falling edge of the fuel injection pulse, thereby changing the frequency of the fuel injection pulse signal. This generates an asynchronous offset of 10 Hz; the procedure transforms the periodic aerodynamic excitation generated by discrete injection into a fluctuating characteristic frequency. The blades are stripped at the inlet without altering the inlet structure to suppress blade start-up stall. The control processor then processes the thermodynamic characteristics. The starting thermal efficiency factor is obtained by performing a normalized convolution operation with the dynamic characteristic quantity. When the starting thermal efficiency factor If the calculation cycle exceeds 1.6 for three consecutive cycles, the system determines that a localized thermal overload has occurred in the combustion chamber due to excessively low atmospheric density, and reduces the fuel injection duty cycle from 35% to 15% to execute an interception action; as the engine speed rises to 40,000... The instantaneous increment of the dynamic characteristic quantity exceeds 200. Furthermore, when the duration reaches 100ms, the system determines that the engine has crossed the thermal equilibrium brittleness range and entered a self-sustaining operation state, ensuring the reproducibility of the controller in the field environment.

[0043] Example 5: In the verification process for the consistency of mechanical resistance of bearings from different batches, the test bench maintains standard atmospheric pressure and 20 The ambient temperature controls the processor to drive the starter motor according to 2000... For the gradient speed step sequence, cold rotation is performed, and the current monitoring unit synchronously collects the real-time drive current at each speed step point. Using the sample points, a first-order linear fit is performed on the speed and current dataset using the least squares method to calculate the torque conversion operator. Its unit is The control processor will use the calibrated torque conversion operator Stored in non-volatile memory, as a reference for subsequent field deployment phases using real-time drive current. In the middle of the calculation of angular acceleration bias The physical benchmark; in the response consistency verification of the exhaust temperature detection unit, a controlled step thermal flow field is used to evaluate the thermal response time constant. Calibration was performed using a constant-temperature hot air source to generate 400... The temperature rise step signal is used to place the exhaust temperature detection unit into the thermal flow field, and the control processor is set to 1 Time resolution recording of raw temperature signals The rising curve was observed, and the original temperature signal was measured. The control processor determines the time interval taken for the temperature to rise from the initial ambient temperature to 63.2% of the initial temperature rise as the thermal response time constant. Its unit is The thermal response time constant As a phase correction parameter in the differential feedforward compensation algorithm, it is used to adjust the thermodynamic characteristic quantities. Align the temperature change trend at the combustion chamber outlet with the physical time axis; determine the thermal response time constant. The temperature step response test procedure was adopted, and the exhaust temperature detection unit was placed in an environment with a constant flow rate and a capacity of 400°C. Within a heat flow field with a temperature step amplitude, the raw temperature signal is recorded using a high-speed data acquisition instrument. The curve showing the increase over time represents the original temperature signal. The time taken for the temperature to rise from the initial ambient temperature to 63.2% of the total temperature rise is defined as the thermal response time constant. Calibration value.

[0044] Determine the torque conversion operator The starter motor needs to be controlled to execute equally spaced speed step commands within the range of 5000rpm to 20000rpm, and the real-time speed at each speed point needs to be recorded. When the volatility is below 0.2% for 10 consecutive sampling periods, it is determined to have entered a quasi-steady state; real-time drive current is collected synchronously. A first-order linear regression equation is used to fit the speed and current data points, and the slope of the resulting fitted curve is used as the torque conversion operator. The quantization parameters are stored in the non-volatile memory unit of the control processor and used as the online calculation of the friction load bias. Basis; Establish dynamic characteristic quantities To thermodynamic characteristic quantity The mapping relationship was determined by calibrating the mapping coefficients through a full-condition frequency sweep test on a ground test bench. Compared with the quasi-steady-state exhaust temperature reference value Within the engine's self-sustaining operating range, the engine speed setpoint was changed in 2000 rpm increments, and the phase-compensated thermodynamic characteristic quantities at each speed equilibrium point were recorded. Dynamic characteristic quantity after deducting losses The phase offset is calculated according to the formula. ,in Phase offset, in units of , This is a thermodynamic characteristic quantity, with units of . , This is a dynamic characteristic quantity, with units of rad / s. 2 , This is the dynamic-to-thermal mapping coefficient, with a value of 0.4. s / rad, Current real-time speed Corresponding to the quasi-steady-state exhaust temperature reference value, in units of By constructing a bivariate correlation matrix and performing residual minimization, the mapping coefficients that make the phase offset approach zero under steady-state conditions are determined. and corresponding temperature reference table; determine the standard reference speed. Initial threshold of standard operating conditions Following sea-level standard atmospheric conditions ( , Bench calibration procedure: First, control the starter motor to drive the engine at a fixed 15% duty cycle to perform cold start. After the speed stabilizes, set the quasi-steady-state speed at this point as the standard reference speed. For micro turbojet engines with a thrust range of 3kg to 50kg, The physical values ​​and the rotor moment of inertia It is inversely proportional to the square root and usually falls on to The interval; then, under this standard operating condition, ignition and start-up are performed, and thermodynamic characteristic quantities are collected under the frontline critical state without turbine overheating and ablation. Relative to dynamic characteristic quantity The maximum permissible phase offset is determined as the initial threshold. ; The engineering physical boundary is limited by the thermal stress limit of the high-temperature alloy material of the turbine blade, which typically ranges from [value missing]. to Determine the density compensation coefficient The multi-altitude / low-pressure chamber simulation step calibration procedure was adopted: under different ambient air pressures or simulated altitudes from 0m to 5000m, the starter motor drive power was kept the same (15% duty cycle), and the cold start quasi-steady-state speed was recorded at each air pressure. Change Simultaneously determine the maximum phase shift threshold that the system can tolerate while ensuring that thermal surge and overheating do not occur in the combustion chamber. Using linear regression to obtain Deviation with rotational speed The decreasing slope yields the density compensation coefficient. Its physical essence is the tightening of the thermal protection margin corresponding to the unit cold rotation speed drift; for different compressor pressure ratios and compressor blade aerodynamic damping characteristics. The applicable value range for the project is: to Real-time correction of safety deviation thresholds requires the control processor to obtain the initial threshold under standard atmospheric pressure conditions. Compared with standard reference speed In the pre-ignition phase of the starting sequence, the quasi-steady-state speed under constant drive power is obtained using the current monitoring unit. By calculating the quasi-steady-state speed With reference speed The deviation is determined by introducing a density compensation coefficient based on the calibration procedure. The current cycle protection limit is adjusted in a linear decreasing manner, so that the protection limit automatically shifts with the fluctuation of ambient density, compensating for the decrease in compressor aerodynamic drag and the deterioration of turbine cooling efficiency caused by the thin air.

[0045] Example 6: In the engineering procedure for offline identification of aerodynamic stall frequency characteristics of the inlet, the control processor is connected to the rotor angular acceleration sampling frequency of 1000Hz. In the original sequence, the test bench simulated airflow distortion conditions of varying intensities by adjusting the intake valves with different blockage ratios. The control processor performed sliding window processing with a 50% overlap rate on each of the acquired 1024 sampling points, used a Blackman window function to suppress spectral leakage, and converted the time-domain fluctuations into frequency-domain energy distributions by performing a radix-2 discrete Fourier transform. This process was used to identify the characteristic frequencies of the fluctuations. At that time, the control processor searches for the maximum point of the power spectral density within a bandwidth of 10Hz to 100Hz, and determines the frequency corresponding to the maximum point as the stall characteristic fundamental frequency under the current operating condition; when the amplitude of the maximum point is not less than 4.2 times the average background noise, the control processor sets the fluctuation characteristic frequency as the minimum frequency. The feature index table is locked and stored as the basis for calculating the frequency avoidance step of the oil supply pulse signal during subsequent online operation.

[0046] When the system faces a pulse interception condition caused by the dynamic evolution of the combustion chamber outlet thermal accumulation rate, the fuel injection duty cycle adjustment step size is determined by executing a program, and the control processor determines the step size based on the phase-compensated thermodynamic characteristics. The second-order rate of change determines the level of thermal runaway trend; the system's internal preset temperature gradient response coefficient Corrected fuel supply duty cycle Determined in the following manner: ,in, The adjusted fuel supply duty cycle is expressed in % (%). The fuel supply duty cycle before adjustment is expressed in % (%). This is the gain adjustment factor, and its unit is... ; Thermodynamic characteristic quantity The second derivative with time, i.e., the acceleration due to temperature rise, is expressed in units of . Determine the gain adjustment factor The calibration procedure employs a combination of dynamic response and lean shutdown margin: On a hardware-in-the-loop test bench or actual test rig, a step duty cycle disturbance is injected into the fuel system, and the second-order rate of change of the fuel duty cycle adjustment and thermodynamic characteristic quantities is measured. The transfer function between them; Set to accelerate temperature rise The feedback gain converges rapidly to zero within 100ms, while the adjusted fuel supply duty cycle is verified. The fuel supply should not be lower than the minimum sustaining fuel supply at the current engine speed to avoid triggering lean-fuel stall; this should be adjusted according to the dynamic response time constant of different fuel pumps and the atomization delay of the nozzles. The applicable value range for the project is: to If thermodynamic characteristic quantities are detected The temperature rise acceleration is 120 Furthermore, for fuel servo systems with a typical response time of 20ms, the calibrated and preset gain adjustment factor... It is 0.05 The calculated duty cycle deduction is 6%, and the control processor reduces the current 30% fuel supply duty cycle to 24%. This procedure achieves nonlinear coupling between the adjustment depth of the discrete pulse and the degree of physical heat energy release, so that the engine can maintain a stable starting thermal balance under different fuel viscosity conditions.

[0047] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A portable ground controller for a micro turbojet engine, characterized in that, It includes an exhaust temperature detection unit, a rotor speed sensing unit, a current monitoring unit, and a control processor: The control processor is electrically connected to the exhaust temperature detection unit, the rotor speed sensing unit, and the current monitoring unit, respectively; the control processor stores the thermal response time constant characterizing the physical heat capacity of the exhaust temperature detection unit. The control processor performs the following operations: based on the raw temperature signal collected by the exhaust temperature detection unit and the thermal response time constant, it calculates the thermodynamic characteristic quantity reflecting the transient temperature evolution trend of the combustion chamber outlet airflow through differential feedforward compensation. The rotor angular acceleration is calculated based on the real-time rotational speed collected by the rotor speed sensing unit, and a resistance mapping model that fluctuates with the current ambient temperature is established based on the cold rotation current intensity obtained by the current monitoring unit during the cold rotation stage before engine ignition. By subtracting the bearing friction torque loss term from the rotor angular acceleration using a resistance mapping model, dynamic characteristic quantities reflecting the effective work capacity of the rotor are generated. Real-time monitoring of the phase shift of thermodynamic characteristics relative to dynamic characteristics, and identification of the transient matching degree between the combustion chamber outlet internal energy release rate and the rotor kinetic energy growth rate based on the phase shift. When the phase offset exceeds the preset safety deviation threshold, a fuel shut-off command is output to the fuel system actuator to perform a protective action during the initial thermal buildup evolution stage of startup.

2. The portable ground controller for a micro turbojet engine according to claim 1, characterized in that, The logic for controlling the processor to calculate thermal characteristic quantities includes: acquiring the rate of change of the original temperature signal over time in real time; multiplying the rate of change by the thermal response time constant to obtain a compensation correction value; and summing the compensation correction value with the original temperature signal to offset the sensing lag caused by the heat capacity of the exhaust temperature detection unit.

3. A portable ground controller for a micro turbojet engine according to claim 1, characterized in that, The logic for controlling the processor to generate dynamic characteristic quantities includes: determining the basic friction load of the engine under the current environment based on the cold rotation current intensity, and using it as the zero-point reference of the resistance mapping model; during the engine start-up and acceleration phase, determining the dynamic friction torque at the corresponding speed through the resistance mapping model, and subtracting the acceleration component corresponding to the dynamic friction torque from the rotor angular acceleration.

4. A portable ground controller for a micro turbojet engine according to claim 1, characterized in that, The signal sampling frequency of the control processor is set to be no less than 100Hz, and the control processor triggers a fuel shut-off command when the growth slope of the thermodynamic characteristic quantity deviates positively from the growth slope of the dynamic characteristic quantity.

5. A portable ground controller for a micro turbojet engine according to claim 1, characterized in that, The system also includes an integrated control housing, with the control processor fixed inside the integrated control housing, and an aviation electrical connector for interfacing with the external wiring harness of the micro turbojet engine on the outside of the integrated control housing.

6. A portable ground controller for a micro turbojet engine according to claim 1, characterized in that, The control processor dynamically calculates the safety deviation threshold based on the preset operating condition envelope, and when the phase offset exceeds the safety deviation threshold for a duration of 50ms, the control processor outputs a fuel shut-off command.

7. A portable ground controller for a micro turbojet engine according to claim 1, characterized in that, The real-time calculation of thermodynamic characteristic quantities follows the formula: ,in, It is a thermodynamic characteristic quantity. This represents the temperature value corresponding to the original temperature signal. The thermal response time constant is expressed in seconds. The rate of change of temperature over time, in units of / s.

8. A portable ground controller for a micro turbojet engine according to claim 1, characterized in that, The control processor also stores sensor aging correction factors determined based on the engine's historical starting cycle count. The control processor performs online numerical correction of the thermal response time constant based on the sensor aging correction factors.

9. A portable ground controller for a micro turbojet engine according to claim 1, characterized in that, If the control processor detects that the power characteristic quantity does not produce a positive step of a preset amplitude within a preset time after the ignition pulse is emitted, it determines that the start-up has failed and forcibly executes the fuel shut-off command.

10. A portable ground controller for a micro turbojet engine according to claim 1, characterized in that, The control processor monitors the system's bus voltage in real time through the current monitoring unit, and executes power drop protection logic by reducing the judgment weight of the power characteristic quantity when the bus voltage is lower than 10V.

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