Frequency response identification device and method for linear fuel metering device

Abstract

The invention provides a frequency response identification device and method for a linear fuel metering device. The device comprises an upper computer module, an operation control unit, a power inversion unit, a permanent magnet servo motor, a ball screw, a coupler, a linear metering valve, an LVDT, a rotary transformer encoding and decoding module, a rotor position signal conditioning module, a motor phase current monitoring module, a pressure sensor, a pressure signal conditioning module and a valve stroke signal conditioning module. A linear metering valve frequency response identification module; and a linear metering valve Pode diagram data statistics module.

Description

Technical Field

[0001] This invention belongs to the field of aero-engine control, and specifically relates to a frequency response identification device and method for a linear fuel metering device. Background Technology

[0002] Fuel metering devices are used to accurately measure fuel flow. As a key feedback component in aero-engine control, they are crucial to engine control performance and reliability. The linear fuel metering valve, as the core component of the metering device, directly affects fuel flow measurement and control due to its opening, closing, and adjustment accuracy. Its precise control model serves as the basis for the design of aero-engine digital electronic controllers. Currently, component-level models of fuel metering devices are relatively easy to provide. However, after assembling multiple components, the overall model is difficult to provide due to the coupling between components. This leads to the frequent use of trial-and-error methods and empirical parameter methods in the design of control algorithms in electronic controllers, lacking a positive design basis in the frequency domain. Fault location is particularly difficult after a control system failure, primarily due to the lack of a control model for the fuel metering device. Summary of the Invention

[0003] This invention proposes a frequency response identification device and method for a linear fuel metering device, which can solve the problem of difficulty in fault location after a control system failure.

[0004] In a first aspect, this application provides a frequency response identification device for a linear fuel metering device, comprising: a host computer module, a computing control unit, a power inverter unit, a permanent magnet servo motor, a ball screw, a coupling, a linear metering valve, an LVDT, a rotary transformer encoding / decoding module, a rotor position signal conditioning module, a motor phase current monitoring module, a pressure sensor, a pressure signal conditioning module, a valve stroke signal conditioning module, a linear metering valve frequency response identification module, and a linear metering valve Bode plot data statistics module, wherein: The host computer module is connected to the computing control unit; the computing control unit is connected to the host computer, the rotary transformer encoding / decoding module, the power inverter unit, the motor phase current monitoring module, the pressure signal conditioning module, the valve travel signal conditioning module, and the linear metering valve frequency response identification module; the power inverter unit is connected to the computing control unit and the permanent magnet servo motor; the permanent magnet servo motor is connected to the power inverter unit, the rotor position signal conditioning module, the motor phase current monitoring module, and the ball screw; the ball screw is connected to the permanent magnet servo motor and the coupling; the coupling is connected to the ball screw and the linear metering valve; the linear metering valve is connected to the coupling, the LVDT, and the pressure sensor; the LVDT is connected to the valve travel signal conditioning module and the linear metering valve; the rotary transformer encoding / decoding module is connected to the rotor position signal conditioning module and the computing control unit; the rotor position signal conditioning module is connected to the permanent magnet servo motor and the rotary transformer encoding / decoding module; the motor phase current monitoring module is connected to the permanent magnet servo motor and the computing control unit; the pressure sensor is connected to the linear metering valve and the pressure signal conditioning module. The pressure signal conditioning module is connected to the pressure sensor and the calculation and control unit respectively; the valve stroke signal conditioning module is connected to the LVDT and the calculation and control unit respectively; the linear metering valve frequency response identification module is connected to the calculation and control unit and the linear metering valve Bode plot data statistics module respectively; the linear metering valve Bode plot data statistics module is connected to the linear metering valve frequency response identification module.

[0005] Specifically, the host computer module is used to interact with the computing and control unit, send motion commands to the device, and visualize the measurement results of the measuring device; The computation and control unit is the core of the device's computation and control. It includes a vector control module and a servo control algorithm module. It outputs a PWM signal, which is converted into a power signal by the power inverter unit and output to the motor winding. On the other hand, it reads AD acquisition information and calculates the motor speed and valve stroke through rotor position information. The servo control algorithm module is used to complete the closed-loop control of the valve linear stroke LVDT position, speed, and current. The vector control module is used to output a PWM signal based on the motor rotor position and motor phase current, combined with the servo control algorithm module. The power inverter unit is used to convert the control PWM signal output by the computing and control unit into a power PWM signal, thereby driving the permanent magnet servo motor to move. The permanent magnet servo motor is used to drive the linear metering valve to move through the coupling under control, thereby realizing fuel flow regulation. At the same time, it feeds back the motor phase current to the current sensor and the motor rotor position to the signal conditioning module.

[0006] Specifically, the ball screw is used to convert the linear motion of the permanent magnet servo motor into linear motion; The coupling is used to connect the lead screw and the metering valve shaft so that the two move synchronously in a straight line. The linear metering valve is optional and can be installed under motor drive to realize fuel flow metering and control. The LVDT is used to measure and provide feedback on the valve travel. It outputs a voltage signal through electromagnetic induction. The voltage amplitude is proportional to the displacement, and the phase reflects the direction of motion. The rotary transformer encoding and decoding module is used to generate a rotary transformer excitation signal, output it to the rotor position signal conditioning module, receive the feedback signal output by the rotor position signal conditioning module, and calculate the motor rotor position based on the phase relationship between the excitation signal and the feedback signal. The rotor position signal conditioning module is used to receive the excitation signal from the rotary transformer encoding and decoding module, condition the signal and output it to the rotary transformer, and receive the feedback signal from the rotary transformer, condition it and output it to the rotary transformer encoding and decoding module. The motor phase current monitoring module is used to monitor the phase current of the three-phase windings of the motor and convert the current signal into a voltage signal suitable for microprocessor sampling. The valve travel signal conditioning module converts the signal acquired by the LVDT into a voltage signal suitable for microprocessor sampling; The pressure sensor module is used to monitor the outlet pressure of the fuel metering device; The pressure signal conditioning module is used to convert the signal collected by the sensor into a voltage signal suitable for sampling by the microprocessor. The linear metering valve frequency response identification module is used to identify the amplitude frequency response and phase frequency response of the fuel metering device through a frequency response identification algorithm, and generate amplitude gain and phase hysteresis data corresponding to each frequency point. The linear metering valve Bode plot data statistics module is used to collect the amplitude gain and phase lag data generated by the frequency response identification module, and convert them according to the amplitude and frequency representation units of the Bode plot, so that the frequency response data conforms to the display units of the Bode plot.

[0007] Specifically, the arithmetic control unit includes a high-speed AD converter, an arithmetic control unit, a logic unit, a data storage unit, and a program storage unit. The arithmetic control unit monitors the LVDT position in real time and receives LVDT position commands from the host computer. It transmits the LVDT position commands and the valve position to the servo control algorithm module. The servo algorithm module and the vector control module cooperate to realize LVDT position servoing. The vector control module outputs the PWM duty cycle command to the arithmetic control unit, which controls the six-channel complementary duty cycle output.

[0008] Specifically, the servo control algorithm module includes: LVDT position control algorithm, speed control algorithm, direct-axis current id control algorithm, and quadrature-axis current iq control algorithm; The position control algorithm receives the position command sent by the host computer, calculates the deviation between the actual measured LVDT position and the position, and implements closed-loop control. The controller is a P controller. The position control algorithm outputs the speed command to the speed control algorithm. The speed control algorithm receives the speed command output by the position loop and the motor rotor position, calculates the actual speed after differentiation, and the deviation between the two calculations is used by the speed controller to implement closed-loop speed control. The speed controller is a PI controller, and the speed loop outputs the quadrature-axis current command iq. The quadrature axis current iq control algorithm receives the quadrature axis current command output by the speed loop and the iq current feedback output by the vector control module. The deviation between the two is calculated and closed-loop control is performed by the iq current controller, which outputs voltage uq to the vector control module. The iq current controller is a PI controller. The direct-axis current id control algorithm calculates the deviation between the id current command (0) and the iq current feedback output from the vector control module. The iq current controller performs closed-loop control and outputs voltage uq to the vector control module. The iq current controller is a PI controller.

[0009] Secondly, this application provides a method for frequency response identification of a linear fuel metering device, including: Step 1: Frequency response identification preparation, used to confirm whether the device frequency response identification conditions are met. If the conditions are met, proceed to the frequency response identification plan; if not, check the identification conditions. Step 2: Frequency response identification plan, used to determine the LVDT position generation method and LVDT position change pattern for frequency response identification; Step 3: Frequency response identification process, used during the execution of the frequency response identification plan to measure the amplitude of the LVDT position at each frequency point, the amplitude of the outlet pressure, the amplitude ratio of the outlet pressure to the LVDT position, the zero-phase position of the LVDT position at each frequency point, the zero-phase position of the outlet pressure, and the hysteresis phase angle of the outlet pressure to the zero-phase position of the LVDT position. Step 4: Frequency response results statistics, used to calculate the amplitude ratio and phase difference of the outlet pressure to the rotor position at each frequency point, forming amplitude-frequency characteristic and phase-frequency characteristic data.

[0010] Specifically, step 1 includes: Step 11: Deploy the fuel metering device to the test bench. Connect the fuel booster pump to the front end of the metering device and connect the flow meter and fixed nozzle to the rear end of the metering device. Start the fuel booster pump and run it to the rated speed. Step 12: The host computer sends the initial position of the LVDT, and the servo motor drives the linear valve to the initial position. Monitor the regulator outlet pressure and fuel flow. When both pressure and fuel flow are zero, proceed to step 13. If the pressure and flow cannot return to zero, terminate the identification preparation and recheck the test conditions. Step 13: The host computer sends the LVDT intermediate position, and the servo motor drives the linear valve to the intermediate position. Monitor the regulator outlet pressure and fuel flow. When the pressure and fuel flow are both within the small range of the intermediate position, proceed to step 14. If the pressure and flow cannot reach the expected position, terminate the identification preparation and recheck the test conditions. Step 14: The host computer sends the maximum position of LVDT, and the servo motor drives the linear valve to operate to the maximum position. Monitor the regulator outlet pressure and fuel flow. When the pressure and fuel flow are both within a small range of the maximum position, the identification preparation ends and the identification preparation completion flag is set, and proceed to step 2. If the pressure and flow cannot reach the expected position, the identification preparation is terminated and the test conditions are rechecked.

[0011] Specifically, step 2 includes: Step 21: The host computer sends the LVDT middle position, and the servo motor drives the linear valve to move forward to the middle position. After the valve stabilizes at the middle position, proceed to step 22. Step 22: Using the middle position of the LVDT as the DC bias, add f1 as the starting frequency, fstep as the step, and f2 as the ending frequency to the LVDT position command. The amplitude is a sinusoidal disturbance of 5% of the rated stroke of the valve. The device controls the motor to follow this position command. Each step frequency command lasts for NN cycles.

[0012] Specifically, step 3 includes: Step 31: Under the sinusoidal disturbance command, the LVDT fluctuates sinusoidally around the middle position, and the outlet pressure of the metering device will fluctuate sinusoidally. Step 32: Statistically calculate the bidirectional zero-crossing points of the measured LVDT position and metering device outlet pressure at each frequency, and calculate the phase delay of pressure tracking of LVDT position accordingly; Statistically calculate the sine amplitude of LVDT position and the sine amplitude of outlet pressure, and calculate the amplitude ratio of metering device outlet pressure tracking of LVDT position accordingly.

[0013] Step 33: The bidirectional zero-crossing point statistical method of the LVDT position is as follows: with Ts as the statistical period, the LVDT position statistically recorded in the current sampling period is denoted as L(k), the LVDT position in the next statistical period is denoted as L(k+1), and the corresponding intermediate position before the perturbation is denoted as L(0). Muti(L) = (L(k) - L(0)) * (L(k+1) - L(0)); if Muti(L) < 0, then the corresponding L(k) is a zero-crossing point; Step 34: The bidirectional zero-crossing point statistical method for the outlet pressure of the metering device is as follows: with Ts as the statistical period, the outlet pressure statistically recorded in the current sampling period is P(k), the rotor position in the next statistical period is P(k+1), and the corresponding intermediate position before the disturbance is P(0). Muti(P) = (P(k) - P(0)) * (P(k+1) - P(0)); if Muti(P) < 0, then the corresponding P(k) is the zero-crossing point. Step 35: Let t0 be the zero-crossing time of the LVDT position. Starting from t0, the number of zero-crossing difference cycles N=0. Start searching for the first zero-crossing time of the metering device outlet pressure, denoted as t1. Perform N+1 operations in each sampling cycle, with a sampling period of Ts. At time t1, t1-t0=N*Ts. Let k=N, then the time difference between the zero-crossing point of a single rotor position and the zero-crossing point of the outlet pressure is k*Ts. Step 36: Each frequency point lasts for NN cycles, for a total of 2NN zero-crossing points. The time differences of the 2NN zero-crossing points are weighted and averaged to obtain the average zero-crossing time difference as kave* Ts. Step 37: Let the frequency of the current sinusoidal disturbance be f(k). The phase lag angle corresponding to this frequency point is calculated as follows: Llag(k) = kave * Ts * f(k) * 360; Step 38: Let L(k) be the zero-crossing point of the valve position. Starting from this zero-crossing point, traverse the point with the maximum amplitude of the LVDT position within (1 / f(k)) / Ts sampling periods, and denote it as Lmax(k). Take the weighted average of Lmax(k) for NN sampling periods to obtain Lmaxave(k). Step 39: Let P(k) be the zero-crossing point of the outlet pressure of the metering device. Starting from this zero-crossing point, within (1 / f(k)) / Ts sampling periods, traverse the point with the maximum amplitude of the outlet pressure of the metering device, and denote it as Pmax(k). Take the weighted average of Pmax(k) for NN sampling periods to obtain Pmaxave(k). Step 310: The method for calculating the amplitude ratio of the metering device outlet pressure to the LVDT position tracking is as follows: Let the sinusoidal amplitude of the metering device outlet pressure corresponding to each traversal frequency point f(k) be Pmaxave(k), and the sinusoidal amplitude of the LVDT position be Lmaxave(k); then the amplitude ratio gain K(k) corresponding to this frequency point is = Pmaxave(k) / Lmaxave(k).

[0014] Specifically, step 4 includes: Step 41: Record the amplitude ratio K(k) and phase difference Llag(k) corresponding to each frequency point f(k). Compress the frequency coordinates according to the logarithmic representation method of Bode plot frequency points and save the data. Step 42: Draw the Bode plot amplitude-frequency response and phase-frequency response diagrams based on the Bode plot data.

[0015] In summary, this invention proposes a frequency response identification device and method for a linear fuel metering device. By identifying the amplitude-frequency and phase-frequency characteristics of the metering device, it provides a basis for constructing the transfer function of the metering device; it also provides a basis for the design of the metering device control algorithm, fault diagnosis, and health management; and it lays the foundation for the safe and reliable control of aero-engine operation. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a frequency response identification device for a linear fuel metering device proposed in this invention. Figure 2 This is a schematic diagram of the structure of a rotary transformer excitation signal conditioner proposed in this invention; Figure 3 This is a schematic diagram of the structure of a rotary transformer output signal conditioner proposed in this invention; Figure 4 This is a schematic diagram of the structure of a power inverter unit proposed in this invention; Figure 5 This is a schematic diagram of the structure of a vector control module proposed in this invention; Figure 6 This is a schematic diagram of the structure of a servo control algorithm module proposed in this invention; Figure 7 This is a schematic diagram of the structure of a pressure signal conditioning module proposed in this invention; Figure 8 This is a schematic diagram of a frequency response identification structure proposed in this invention. Detailed Implementation

[0017] The main function of the linear fuel metering device is to convert the linear motion of the motor into linear motion using a permanent magnet servo motor and a ball screw, drive the linear valve to produce displacement, change the valve and bushing window area, and thus realize fuel flow metering. The valve stroke is monitored through LVDT.

[0018] Example 1 like Figure 1 As shown, this application provides a frequency response identification device for a linear fuel metering device, comprising: a host computer module, a computing control unit, a power inverter unit, a permanent magnet servo motor, a ball screw, a coupling, a linear metering valve, an LVDT, a rotary transformer encoding / decoding module, a rotor position signal conditioning module, a motor phase current monitoring module, a pressure sensor, a pressure signal conditioning module, a valve stroke signal conditioning module, a linear metering valve frequency response identification module, and a linear metering valve Bode plot data statistics module, wherein: The host computer module is connected to the computing control unit; the computing control unit is connected to the host computer, the rotary transformer encoding / decoding module, the power inverter unit, the motor phase current monitoring module, the pressure signal conditioning module, the valve travel signal conditioning module, and the linear metering valve frequency response identification module; the power inverter unit is connected to the computing control unit and the permanent magnet servo motor; the permanent magnet servo motor is connected to the power inverter unit, the rotor position signal conditioning module, the motor phase current monitoring module, and the ball screw; the ball screw is connected to the permanent magnet servo motor and the coupling; the coupling is connected to the ball screw and the linear metering valve; the linear metering valve is connected to the coupling, the LVDT, and the pressure sensor; the LVDT is connected to the valve travel signal conditioning module and the linear metering valve; the rotary transformer encoding / decoding module is connected to the rotor position signal conditioning module and the computing control unit; the rotor position signal conditioning module is connected to the permanent magnet servo motor and the rotary transformer encoding / decoding module; the motor phase current monitoring module is connected to the permanent magnet servo motor and the computing control unit; the pressure sensor is connected to the linear metering valve and the pressure signal conditioning module. The pressure signal conditioning module is connected to the pressure sensor and the calculation and control unit respectively; the valve stroke signal conditioning module is connected to the LVDT and the calculation and control unit respectively; the linear metering valve frequency response identification module is connected to the calculation and control unit and the linear metering valve Bode plot data statistics module respectively; the linear metering valve Bode plot data statistics module is connected to the linear metering valve frequency response identification module.

[0019] Specifically, the host computer module is used to interact with the computing and control unit, send motion commands to the device, and visualize the measurement results of the measuring device; The computation and control unit is the core of the device's computation and control. It includes a vector control module and a servo control algorithm module. It outputs a PWM signal, which is converted into a power signal by the power inverter unit and output to the motor winding. On the other hand, it reads AD acquisition information and calculates the motor speed and valve stroke through rotor position information. The servo control algorithm module is used to complete the closed-loop control of the valve linear travel (LVDT) position, speed, and current. The vector control module is used to output a PWM signal based on the motor rotor position and motor phase current, combined with the servo control algorithm module. The power inverter unit is used to convert the control PWM signal output by the computing and control unit into a power PWM signal, thereby driving the permanent magnet servo motor to move. The permanent magnet servo motor is used to drive the linear metering valve to move through the coupling under control to achieve fuel flow regulation. At the same time, it feeds back the motor phase current to the current sensor and the motor rotor position to the signal conditioning module. The ball screw is used to convert the linear motion of the permanent magnet servo motor into linear motion. The coupling is used to connect the lead screw and the metering valve shaft so that the two move synchronously in a straight line. The linear metering valve is optional and can be installed under motor drive to realize fuel flow metering and control. The LVDT is used to measure and provide feedback on the valve travel. It outputs a voltage signal through electromagnetic induction. The voltage amplitude is proportional to the displacement, and the phase reflects the direction of motion. The rotary transformer encoding and decoding module is used to generate a rotary transformer excitation signal, output it to the rotor position signal conditioning module, receive the feedback signal output by the rotor position signal conditioning module, and calculate the motor rotor position based on the phase relationship between the excitation signal and the feedback signal. The rotor position signal conditioning module is used to receive the excitation signal from the rotary transformer encoding and decoding module, condition the signal and output it to the rotary transformer, and receive the feedback signal from the rotary transformer, condition it and output it to the rotary transformer encoding and decoding module. The motor phase current monitoring module is used to monitor the phase current of the three-phase windings of the motor and convert the current signal into a voltage signal suitable for microprocessor sampling. The valve travel signal conditioning module converts the signal acquired by the LVDT into a voltage signal suitable for microprocessor sampling; The pressure sensor module is used to monitor the outlet pressure of the fuel metering device; The pressure signal conditioning module is used to convert the signal collected by the sensor into a voltage signal suitable for sampling by the microprocessor. The linear metering valve frequency response identification module is used to identify the amplitude frequency response and phase frequency response of the fuel metering device through a frequency response identification algorithm, and generate amplitude gain and phase hysteresis data corresponding to each frequency point. The linear metering valve Bode plot data statistics module is used to collect the amplitude gain and phase lag data generated by the frequency response identification module, and convert them according to the amplitude and frequency representation units of the Bode plot, so that the frequency response data conforms to the display units of the Bode plot.

[0020] Specifically, when the test device is in operation, it is deployed on a ground platform, and the system is pressurized by a fuel pump to provide the fuel pressure and hydraulic force required for the operation of the linear fuel metering device.

[0021] Specifically, the permanent magnet servo motor is installed using fixed fixtures to ensure reliable motor support. The motor shaft is concentric with the valve shaft, and after the motor and metering valve are connected via a coupling, the motor is almost unaffected by radial forces during movement. The permanent magnet servo motor includes three-phase windings (A, B, and C) and integrates a rotary transformer for rotor position measurement. The rotor of the rotary transformer is coaxial with the motor rotor, and the zero point of the rotary transformer is aligned with the zero-crossing point of the opposite electromotive force of motor A. Specifically, the arithmetic control unit is the core of the arithmetic control of the measuring device. It contains a high-speed AD converter, arithmetic control unit, logic unit, data storage unit, program storage unit, etc. The computation control unit monitors the LVDT position in real time and receives LVDT position commands from the host computer. It transmits the LVDT position commands and the valve position (LVDT position) to the servo control algorithm module. The servo algorithm module and the vector control module cooperate to realize LVDT position servoing. The vector control module outputs the PWM duty cycle command to the computation control unit, which controls the six-channel complementary duty cycle output.

[0022] Specifically, the rotary transformer encoding / decoding module generates a sinusoidal excitation signal with an output frequency of fsolve, an amplitude of amp1, and a DC bias of amp2; it receives a sine differential and cosine differential signal with a DC bias of amp2 and a peak value of amp3 from the rotor position signal conditioning module; the internal position calculation algorithm calculates the rotor position, and the calculation result is output to the arithmetic control unit via a parallel bus.

[0023] Specifically, the rotor position signal conditioning module includes: a rotary transformer excitation signal conditioner and a rotary transformer output signal conditioner; like Figure 2 As shown, the sinusoidal signal with amplitude amp1 output from the resolver encoder / decoder module is amplified using high-bandwidth power amplification, increasing the peak-to-peak value to amp4. The resolver excitation signal conditioner consists of an active filter bias circuit and a voltage amplifier circuit connected in series. The active filter bias circuit superimposes the sinusoidal signal with amplitude amp1 output from the resolver excitation signal generator with the DC bias signal amp2, and then performs a second-order active Chebyshev filter on the signal. The filter parameters are adjusted by resistors and capacitors.

[0024] like Figure 3As shown, the output signal conditioner of the rotary transformer consists of an electrostatic discharge (ESD) protector, an active filter, and a signal amplifier connected in series. The ESD protector is used to prevent damage to the subsequent circuitry caused by static electricity from the human body during the insertion and removal of the rotary transformer's electrical connector. The active filter is a second-order active Chebyshev filter with DC bias function, and its parameter configuration is consistent with that of the excitation signal conditioner. The signal amplifier is used to condition the signal with a peak value of amp1 from the rotary transformer output into a sine differential and cosine differential signal with a peak value of amp5.

[0025] Specifically, such as Figure 4 As shown, the power inverter unit includes a gate driver and a power inverter unit connected in sequence; The gate driver receives the TTL signal output by the operational control unit and converts it into a signal with a strong drive current of 15V required for each MOS transistor of the power inverter unit to operate. The power inverter unit receives the control signal from the gate driver and, under the control of the gate driver, realizes the switching of the MOS transistor; the gate driver and the power inverter unit work together to realize the conversion of TTL signal to power signal.

[0026] Specifically, the motor phase current monitoring module includes: a Hall current sensor, a signal conditioner, and a current measuring device connected in sequence.

[0027] The primary terminal of the Hall current sensor is connected in series in each phase line of the motor. When the motor phase current flows through the Hall sensor, the secondary terminal of the sensor will sense the corresponding voltage, realizing the I / V conversion from current to voltage. The signal conditioner is a voltage follower connected in series with an RC low-pass filter. The voltage signal output by the current sensor is connected to the non-inverting input of the follower, the inverting input of the follower is connected to the output, and the output of the follower is connected to the RC filter. The current measuring device periodically samples the RC-filtered voltage value at the fsolve frequency, and combines the correspondence between the Hall current sensor current and the output voltage to calculate the motor phase current in reverse from the voltage value.

[0028] Specifically, such as Figure 5 As shown, the vector control module includes a Clark transform module, a Park transform module, an inverse Park transform module, and an SVPWM vector calculation module; The Clark transformation module, based on the principle of amplitude equivalence, transforms the three-phase AC current into two-phase currents iα and iβ in a stationary coordinate system. The Park transformation integrates iα, iβ, and the motor rotor position θ to calculate the direct-axis current id and quadrature-axis current iq in the rotating coordinate system. The inverse Park transformation receives the direct-axis voltage Ud, quadrature-axis voltage Uq, and motor rotor position θ output by the servo control algorithm module, and converts the voltages in the two-phase rotating coordinate system into voltages Uα and Uβ in the two-phase stationary coordinate system. The SVPWM vector calculation module performs sector analysis, vector calculation, and correction based on Uα and Uβ, and outputs 6-channel PWM.

[0029] Specifically, such as Figure 6 As shown, the servo control algorithm module includes: LVDT position control algorithm, speed control algorithm, direct axis current id control algorithm, and quadrature axis current iq control algorithm.

[0030] The position control algorithm receives the position command sent by the host computer, calculates the deviation between the actual measured LVDT position and the position, and implements closed-loop control. The controller is a P controller. The position control algorithm outputs the speed command to the speed control algorithm. The speed control algorithm receives the speed command output by the position loop and the motor rotor position, calculates the actual speed after differentiation, and the deviation between the two calculations is used by the speed controller to implement closed-loop speed control. The speed controller is a PI controller, and the speed loop outputs the quadrature-axis current command iq. The quadrature axis current iq control algorithm receives the quadrature axis current command output by the speed loop and the iq current feedback output by the vector control module. The deviation between the two is calculated and closed-loop control is performed by the iq current controller, which outputs voltage uq to the vector control module. The iq current controller is a PI controller. The direct-axis current id control algorithm calculates the deviation between the id current command (0) and the iq current feedback output from the vector control module. The iq current controller performs closed-loop control and outputs voltage uq to the vector control module. The iq current controller is a PI controller.

[0031] Specifically, the pressure sensor is a piezoresistive pressure sensor that receives a current excitation source and feeds back a voltage signal corresponding to the fuel pressure.

[0032] Specifically, such as Figure 7 As shown, the pressure signal conditioning module includes: excitation signal and pressure sensor signal conditioning; The signal excitation source generates the constant current required for the pressure sensor to operate. It consists of a voltage reference module and a voltage-controlled constant current source. The voltage-controlled constant current source receives the voltage input from the voltage reference module and generates current. The voltage value corresponding to the constant current is determined by the characteristics of the voltage-controlled constant current source itself. The voltage reference module is a high-precision reference source with feedback adjustment.

[0033] The sensor signal conditioning process involves receiving the weak voltage output from the pressure sensor, amplifying the signal to a 0-3V voltage signal using an integrating operational amplifier, adjusting the integration time constant using capacitor C1 (the time constant is determined based on the signal noise level), and performing high-speed AD conversion at the fsample sampling frequency. The sampling result is then converted into a physical pressure value based on the correlation between voltage and fuel pressure.

[0034] Specifically, the linear metering valve frequency response identification module includes: linear metering valve frequency response identification preparation, linear metering valve frequency response identification plan, linear metering valve frequency response identification implementation, and linear metering valve frequency response result statistics.

[0035] The method for preparing the frequency response identification of the linear metering gate is as follows: Deploy the fuel metering device on the test bench. Connect the fuel booster pump to the front end of the metering device and connect the flow meter and fixed nozzle to the rear end of the metering device. Start the fuel booster pump and run it to the rated speed. The host computer sends the LVDT initial position, and the servo motor drives the linear valve to the initial position. The regulator outlet pressure and fuel flow are monitored. When both pressure and fuel flow are zero, the next stage begins. If the pressure and flow cannot return to zero, the identification preparation is terminated and the test conditions are rechecked. The host computer sends the LVDT intermediate position, and the servo motor drives the linear valve to operate to the intermediate position. The regulator outlet pressure and fuel flow are monitored. When the pressure and fuel flow are both within the small range of the intermediate position, the next stage is entered. If the pressure and flow cannot reach the expected position, the identification preparation is terminated and the test conditions are rechecked. The host computer sends the maximum position of LVDT, and the servo motor drives the linear valve to operate to the maximum position. The regulator outlet pressure and fuel flow are monitored. When the pressure and fuel flow are both within a small range of the maximum position, the identification preparation ends and the identification preparation completion flag is set. If the pressure and flow cannot reach the expected position, the identification preparation is terminated and the test conditions are rechecked. The frequency response identification scheme for the linear metering valve is as follows: The host computer sends the LVDT intermediate position, and the servo motor drives the linear valve to advance to the intermediate position. After the valve stabilizes at the intermediate position, the frequency response identification program is entered. With the LVDT middle position as DC bias, the LVDT position command is superimposed with f1 as the starting frequency, fstep as the step, and f2 as the ending frequency, with an amplitude of 5% of the valve's rated stroke as a sinusoidal disturbance. The device controls the motor to follow this position command, and each step frequency command lasts for 10 cycles. Under the sinusoidal disturbance command, the LVDT fluctuates sinusoidally around the middle position, and the outlet pressure of the metering device will fluctuate sinusoidally. like Figure 8 As shown, the measured LVDT position and metering device outlet pressure at each frequency are statistically analyzed to determine the bidirectional zero-crossing points, and the phase delay of pressure tracking of LVDT position is calculated accordingly. The sine amplitude of LVDT position and the sine amplitude of outlet pressure are statistically analyzed to calculate the amplitude ratio of metering device outlet pressure tracking of LVDT position.

[0036] The bidirectional zero-crossing point statistical method for LVDT position is as follows: with Ts as the statistical period, the LVDT position statistically recorded in the current sampling period is denoted as L(k), the LVDT position in the next statistical period is denoted as L(k+1), and the corresponding intermediate position before the perturbation is denoted as L(0). Muti(L) = (L(k) - L(0)) * (L(k+1) - L(0)); if Muti(L) < 0, then the corresponding L(k) is a zero-crossing point. The bidirectional zero-crossing statistical method for the outlet pressure of the metering device is as follows: with Ts as the statistical period, the outlet pressure statistically recorded in the current sampling period is P(k), the rotor position in the next statistical period is P(k+1), and the corresponding intermediate position before the disturbance is P(0). Muti(P) = (P(k) - P(0)) * (P(k+1) - P(0)); if Muti(P) < 0, then the corresponding P(k) is the zero-crossing point. The method for measuring the phase delay of the outlet pressure for LVDT position tracking is as follows: Let t0 be the zero-crossing time of the LVDT position. Starting from t0, the number of zero-crossing difference cycles N=0. Start searching for the first zero-crossing time of the metering device outlet pressure, denoted as t1. Perform N+1 operations in each sampling cycle, with a sampling period of Ts. At time t1, we have t1-t0=N*Ts. Let k=N, then the time difference between the zero-crossing point of a single rotor position and the zero-crossing point of the outlet pressure is k*Ts. Each frequency point lasts for NN cycles, with a total of 2NN zero crossings. The time differences of the 2NN zero crossings are weighted and averaged to obtain the average zero crossing time difference as kave*Ts. Let the frequency of the current sinusoidal disturbance be f(k). Then the phase lag angle corresponding to this frequency point is calculated as follows: Llag(k) = kave * Ts * f(k) * 360; The method for measuring the sinusoidal amplitude of the LVDT position is as follows: Let L(k) be the zero-crossing point of the valve position. Starting from this zero-crossing point, within (1 / f(k)) / Ts sampling periods, traverse the point with the maximum amplitude of the LVDT position, denoted as Lmax(k). Take the weighted average of Lmax(k) over NN sampling periods to obtain Lmaxave(k). The method for measuring the sinusoidal amplitude of the outlet pressure of the metering device is as follows: Let P(k) be the zero-crossing point of the outlet pressure of the metering device. Starting from this zero-crossing point, within (1 / f(k)) / Ts sampling periods, traverse the point with the maximum amplitude of the outlet pressure of the metering device, which is denoted as Pmax(k). The weighted average of Pmax(k) for NN sampling periods is obtained as Pmaxave(k). The method for calculating the amplitude ratio of the metering device outlet pressure to the LVDT position tracking is as follows: Let the sinusoidal amplitude of the metering device outlet pressure corresponding to each traversal frequency point f(k) be Pmaxave(k), and the sinusoidal amplitude of the LVDT position be Lmaxave(k); then the amplitude ratio gain K(k) corresponding to this frequency point = Pmaxave(k) / Lmaxave(k); The statistical method for the frequency response results of the linear metering valve is as follows: record the amplitude ratio K(k) and phase difference Llag(k) corresponding to each frequency point f(k), compress the frequency coordinates according to the logarithmic representation method of the frequency points of the Bode plot, save the data, and facilitate the plotting of the amplitude-frequency characteristic and phase-frequency characteristic of the Bode plot.

[0037] In summary, this invention proposes a frequency response identification device for a linear fuel metering device. By identifying the amplitude-frequency and phase-frequency characteristics, the overall transfer function of the metering device can be further constructed, serving as the basis for electronic controller design, as well as for fault diagnosis, health management, and design optimization of the fuel metering device, thus laying the foundation for improving the control performance and operational safety of aero-engines.

[0038] Example 2 This application provides a frequency response identification method for a linear fuel metering device, applied to the frequency response identification device for a linear fuel metering device provided in the above embodiments. The method includes: Step 1: Preparation for frequency response identification of linear metering gate.

[0039] Specifically, step 1 includes: Step 11: Deploy the fuel metering device to the test bench. Connect the fuel booster pump to the front end of the metering device and connect the flow meter and fixed nozzle to the rear end of the metering device. Start the fuel booster pump and run it to the rated speed. Step 12: The host computer sends the initial position of the LVDT, and the servo motor drives the linear valve to the initial position. Monitor the regulator outlet pressure and fuel flow. When both pressure and fuel flow are zero, proceed to step 13. If the pressure and flow cannot return to zero, terminate the identification preparation and recheck the test conditions. Step 13: The host computer sends the LVDT intermediate position, and the servo motor drives the linear valve to the intermediate position. Monitor the regulator outlet pressure and fuel flow. When the pressure and fuel flow are both within the small range of the intermediate position, proceed to step 14. If the pressure and flow cannot reach the expected position, terminate the identification preparation and recheck the test conditions. Step 14: The host computer sends the maximum position of LVDT, and the servo motor drives the linear valve to operate to the maximum position. Monitor the regulator outlet pressure and fuel flow. When the pressure and fuel flow are both within a small range of the maximum position, the identification preparation ends and the identification preparation completion flag is set, and proceed to step 2. If the pressure and flow cannot reach the expected position, terminate the identification preparation and recheck the test conditions. Step 2: Linear Metering Valve Frequency Response Identification Plan. Specifically, this includes the following steps: Step 21: The host computer sends the LVDT middle position, and the servo motor drives the linear valve to move forward to the middle position. After the valve stabilizes at the middle position, proceed to step 22. Step 22: With the LVDT middle position as DC bias, add f1 as the starting frequency, fstep as the step, and f2 as the ending frequency to the LVDT position command. The amplitude is a sinusoidal disturbance of 5% of the rated stroke of the valve. The device controls the motor to follow this position command. Each step frequency command lasts for 10 cycles. Step 3: Frequency response identification process of linear metering valve. Specifically, it includes the following steps: Step 31: Under the sinusoidal disturbance command, the LVDT fluctuates sinusoidally around the middle position, and the outlet pressure of the metering device will fluctuate sinusoidally. Step 32: Statistically calculate the bidirectional zero-crossing points of the measured LVDT position and metering device outlet pressure at each frequency, and calculate the phase delay of pressure tracking of LVDT position accordingly; Statistically calculate the sine amplitude of LVDT position and the sine amplitude of outlet pressure, and calculate the amplitude ratio of metering device outlet pressure tracking of LVDT position accordingly.

[0040] Step 33: The bidirectional zero-crossing point statistical method of the LVDT position is as follows: with Ts as the statistical period, the LVDT position statistically recorded in the current sampling period is denoted as L(k), the LVDT position in the next statistical period is denoted as L(k+1), and the corresponding intermediate position before the perturbation is denoted as L(0). Muti(L) = (L(k) - L(0)) * (L(k+1) - L(0)); if Muti(L) < 0, then the corresponding L(k) is a zero-crossing point; Step 34: The bidirectional zero-crossing point statistical method for the outlet pressure of the metering device is as follows: with Ts as the statistical period, the outlet pressure statistically recorded in the current sampling period is P(k), the rotor position in the next statistical period is P(k+1), and the corresponding intermediate position before the disturbance is P(0). Muti(P) = (P(k) - P(0)) * (P(k+1) - P(0)); if Muti(P) < 0, then the corresponding P(k) is the zero-crossing point. Step 35: Let t0 be the zero-crossing time of the LVDT position. Starting from t0, the number of zero-crossing difference cycles N=0. Start searching for the first zero-crossing time of the metering device outlet pressure, denoted as t1. Perform N+1 operations in each sampling cycle, with a sampling period of Ts. At time t1, t1-t0=N*Ts. Let k=N, then the time difference between the zero-crossing point of a single rotor position and the zero-crossing point of the outlet pressure is k*Ts. Step 36: Each frequency point lasts for NN cycles, with a total of 2NN zero crossings. The time differences of the 2NN zero crossings are weighted and averaged to obtain the average zero crossing time difference as kave*2NN. Step 37: Let the frequency of the current sinusoidal disturbance be f(k). The phase lag angle corresponding to this frequency point is calculated as follows: Llag(k) = kave * Ts * f(k) * 360. Step 38: Let L(k) be the zero-crossing point of the valve position. Starting from this zero-crossing point, traverse the point with the maximum amplitude of the LVDT position within (1 / f(k)) / Ts sampling periods, and denote it as Lmax(k). Take the weighted average of Lmax(k) for NN sampling periods to obtain Lmaxave(k). Step 39: Let P(k) be the zero point of the outlet pressure of the metering device. Starting from this zero point, within (1 / f(k)) / Ts sampling periods, traverse the point with the maximum amplitude of the outlet pressure of the metering device, and denote it as Pmax(k). Take the weighted average of Pmax(k) for NN sampling periods to obtain Pmaxave(k). Step 310: The method for calculating the amplitude ratio of the metering device outlet pressure to the LVDT position tracking is as follows: Let the sinusoidal amplitude of the metering device outlet pressure corresponding to each traversal frequency point f(k) be Pmaxave(k), and the sinusoidal amplitude of the LVDT position be Lmaxave(k); then the amplitude ratio gain K(k) corresponding to this frequency point = Pmaxave(k) / Lmaxave(k); Step 4: Statistical analysis of the frequency response results of the linear metering valve. Specifically, this includes the following steps: Step 41: Record the amplitude ratio K(k) and phase difference Llag(k) corresponding to each frequency point f(k). Compress the frequency coordinates according to the logarithmic representation method of Bode plot frequency points and save the data. Step 42: Draw the Bode plot amplitude-frequency response and phase-frequency response diagrams based on the Bode plot data.

[0041] This invention is primarily used in aero-engine control systems. Its main function is to address the lack of a control model for linear fuel metering devices by designing a frequency response identification device for these devices. This provides a reference for the design and analysis of fuel metering device control algorithms, facilitating algorithm optimization; it also serves as a basis for fault diagnosis and health management of the metering device; and it lays the foundation for improving the control performance and operational safety of aero-engines.

Claims

1. A frequency response identification device for a linear fuel metering device, characterized in that, include: The system includes a host computer module, a computation and control unit, a power inverter unit, a permanent magnet servo motor, a ball screw, a coupling, a linear metering valve, an LVDT (Low Voltage Detector), a rotary transformer encoding / decoding module, a rotor position signal conditioning module, a motor phase current monitoring module, a pressure sensor, a pressure signal conditioning module, a valve travel signal conditioning module, a linear metering valve frequency response identification module, and a linear metering valve Bode plot data statistics module. Among these: The host computer module is connected to the computing control unit; the computing control unit is connected to the host computer, the rotary transformer encoding / decoding module, the power inverter unit, the motor phase current monitoring module, the pressure signal conditioning module, the valve travel signal conditioning module, and the linear metering valve frequency response identification module; the power inverter unit is connected to the computing control unit and the permanent magnet servo motor; the permanent magnet servo motor is connected to the power inverter unit, the rotor position signal conditioning module, the motor phase current monitoring module, and the ball screw; the ball screw is connected to the permanent magnet servo motor and the coupling; the coupling is connected to the ball screw and the linear metering valve; the linear metering valve is connected to the coupling, the LVDT, and the pressure sensor; the LVDT is connected to the valve travel signal conditioning module and the linear metering valve; the rotary transformer encoding / decoding module is connected to the rotor position signal conditioning module and the computing control unit; the rotor position signal conditioning module is connected to the permanent magnet servo motor and the rotary transformer encoding / decoding module; the motor phase current monitoring module is connected to the permanent magnet servo motor and the computing control unit; the pressure sensor is connected to the linear metering valve and the pressure signal conditioning module. The pressure signal conditioning module is connected to the pressure sensor and the calculation and control unit respectively; the valve stroke signal conditioning module is connected to the LVDT and the calculation and control unit respectively; the linear metering valve frequency response identification module is connected to the calculation and control unit and the linear metering valve Bode plot data statistics module respectively; the linear metering valve Bode plot data statistics module is connected to the linear metering valve frequency response identification module.

2. The apparatus according to claim 1, characterized in that, The host computer module is used to interact with the computing and control unit, send motion commands to the device, and visualize the measurement results of the measuring device; The computation and control unit is the core of the device's computation and control. It includes a vector control module and a servo control algorithm module. It outputs a PWM signal, which is converted into a power signal by the power inverter unit and output to the motor winding. On the other hand, it reads AD acquisition information and calculates the motor speed and valve stroke through rotor position information. The servo control algorithm module is used to complete the closed-loop control of the valve linear stroke LVDT position, speed, and current. The vector control module is used to output a PWM signal based on the motor rotor position and motor phase current, combined with the servo control algorithm module. The power inverter unit is used to convert the control PWM signal output by the computing and control unit into a power PWM signal, thereby driving the permanent magnet servo motor to move. The permanent magnet servo motor is used to drive the linear metering valve to move through the coupling under control, thereby realizing fuel flow regulation. At the same time, it feeds back the motor phase current to the current sensor and the motor rotor position to the signal conditioning module.

3. The apparatus according to claim 1, characterized in that, The ball screw is used to convert the linear motion of the permanent magnet servo motor into linear motion. The coupling is used to connect the lead screw and the metering valve shaft so that the two move synchronously in a straight line. The linear metering valve is optional and can be installed under motor drive to realize fuel flow metering and control. The LVDT is used to measure and provide feedback on the valve travel. It outputs a voltage signal through electromagnetic induction. The voltage amplitude is proportional to the displacement, and the phase reflects the direction of motion. The rotary transformer encoding and decoding module is used to generate a rotary transformer excitation signal, output it to the rotor position signal conditioning module, receive the feedback signal output by the rotor position signal conditioning module, and calculate the motor rotor position based on the phase relationship between the excitation signal and the feedback signal. The rotor position signal conditioning module is used to receive the excitation signal from the rotary transformer encoding and decoding module, condition the signal and output it to the rotary transformer, and receive the feedback signal from the rotary transformer, condition it and output it to the rotary transformer encoding and decoding module. The motor phase current monitoring module is used to monitor the phase current of the three-phase windings of the motor and convert the current signal into a voltage signal suitable for microprocessor sampling. The valve travel signal conditioning module converts the signal acquired by the LVDT into a voltage signal suitable for microprocessor sampling; The pressure sensor module is used to monitor the outlet pressure of the fuel metering device; The pressure signal conditioning module is used to convert the signal collected by the sensor into a voltage signal suitable for sampling by the microprocessor. The linear metering valve frequency response identification module is used to identify the amplitude frequency response and phase frequency response of the fuel metering device through a frequency response identification algorithm, and generate amplitude gain and phase hysteresis data corresponding to each frequency point. The linear metering valve Bode plot data statistics module is used to collect the amplitude gain and phase lag data generated by the frequency response identification module, and convert them according to the amplitude and frequency representation units of the Bode plot, so that the frequency response data conforms to the display units of the Bode plot.

4. The apparatus according to claim 1, characterized in that, The arithmetic control unit includes a high-speed AD converter, an arithmetic control unit, a logic unit, a data storage unit, and a program storage unit. The arithmetic control unit monitors the LVDT position in real time and receives LVDT position commands from the host computer. It transmits the LVDT position commands and the valve position to the servo control algorithm module. The servo algorithm module and the vector control module cooperate to realize LVDT position servoing. The vector control module outputs the PWM duty cycle command to the arithmetic control unit, which controls the six-channel complementary duty cycle output.

5. The apparatus according to claim 1, characterized in that, The servo control algorithm module includes: LVDT position control algorithm, speed control algorithm, direct-axis current id control algorithm, and quadrature-axis current iq control algorithm; The position control algorithm receives the position command sent by the host computer, calculates the deviation between the actual measured LVDT position and the position, and implements closed-loop control. The controller is a P controller. The position control algorithm outputs the speed command to the speed control algorithm. The speed control algorithm receives the speed command output by the position loop and the motor rotor position, calculates the actual speed after differentiation, and the deviation between the two calculations is used by the speed controller to implement closed-loop speed control. The speed controller is a PI controller, and the speed loop outputs the quadrature-axis current command iq. The quadrature axis current iq control algorithm receives the quadrature axis current command output by the speed loop and the iq current feedback output by the vector control module. The deviation between the two is calculated and closed-loop control is performed by the iq current controller, which outputs voltage uq to the vector control module. The iq current controller is a PI controller. The direct-axis current id control algorithm calculates the deviation between the id current command (0) and the iq current feedback output from the vector control module. The iq current controller performs closed-loop control and outputs voltage uq to the vector control module. The iq current controller is a PI controller.

6. A method for frequency response identification of a linear fuel metering device, characterized in that, include: Step 1: Frequency response identification preparation, used to confirm whether the device frequency response identification conditions are met. If the conditions are met, proceed to the frequency response identification plan; if not, check the identification conditions. Step 2: Frequency response identification plan, used to determine the LVDT position generation method and LVDT position change pattern for frequency response identification; Step 3: Frequency response identification process, used during the execution of the frequency response identification plan to measure the amplitude of the LVDT position at each frequency point, the amplitude of the outlet pressure, the amplitude ratio of the outlet pressure to the LVDT position, the zero-phase position of the LVDT position at each frequency point, the zero-phase position of the outlet pressure, and the hysteresis phase angle of the outlet pressure to the zero-phase position of the LVDT position. Step 4: Frequency response results statistics, used to calculate the amplitude ratio and phase difference of the outlet pressure to the rotor position at each frequency point, forming amplitude-frequency characteristic and phase-frequency characteristic data.

7. The method according to claim 6, characterized in that, Step 1 includes: Step 11: Deploy the fuel metering device to the test bench. Connect the fuel booster pump to the front end of the metering device and connect the flow meter and fixed nozzle to the rear end of the metering device. Start the fuel booster pump and run it to the rated speed. Step 12: The host computer sends the initial position of the LVDT, and the servo motor drives the linear valve to the initial position. Monitor the regulator outlet pressure and fuel flow. When both pressure and fuel flow are zero, proceed to step 13. If the pressure and flow cannot return to zero, terminate the identification preparation and recheck the test conditions. Step 13: The host computer sends the LVDT intermediate position, and the servo motor drives the linear valve to the intermediate position. Monitor the regulator outlet pressure and fuel flow. When the pressure and fuel flow are both within the small range of the intermediate position, proceed to step 14. If the pressure and flow cannot reach the expected position, terminate the identification preparation and recheck the test conditions. Step 14: The host computer sends the maximum position of LVDT, and the servo motor drives the linear valve to operate to the maximum position. Monitor the regulator outlet pressure and fuel flow. When the pressure and fuel flow are both within a small range of the maximum position, the identification preparation ends and the identification preparation completion flag is set, and proceed to step 2. If the pressure and flow cannot reach the expected position, the identification preparation is terminated and the test conditions are rechecked.

8. The method according to claim 6, characterized in that, Step 2 includes: Step 21: The host computer sends the LVDT middle position, and the servo motor drives the linear valve to move forward to the middle position. After the valve stabilizes at the middle position, proceed to step 22. Step 22: Using the middle position of the LVDT as the DC bias, add f1 as the starting frequency, fstep as the step, and f2 as the ending frequency to the LVDT position command. The amplitude is a sinusoidal disturbance of 5% of the rated stroke of the valve. The device controls the motor to follow this position command. Each step frequency command lasts for NN cycles.

9. The method according to claim 6, characterized in that, Step 3 includes: Step 31: Under the sinusoidal disturbance command, the LVDT fluctuates sinusoidally around the middle position, and the outlet pressure of the metering device will fluctuate sinusoidally. Step 32: Statistically calculate the bidirectional zero-crossing points of the measured LVDT position and metering device outlet pressure at each frequency, and calculate the phase delay of pressure tracking of LVDT position accordingly; Statistically calculate the sine amplitude of LVDT position and the sine amplitude of outlet pressure, and calculate the amplitude ratio of metering device outlet pressure tracking of LVDT position accordingly. Step 33: The bidirectional zero-crossing point statistical method of the LVDT position is as follows: with Ts as the statistical period, the LVDT position statistically recorded in the current sampling period is denoted as L(k), the LVDT position in the next statistical period is denoted as L(k+1), and the corresponding intermediate position before the perturbation is denoted as L(0). Muti(L) = (L(k) - L(0)) * (L(k+1) - L(0)); if Muti(L) < 0, then the corresponding L(k) is a zero-crossing point; Step 34: The bidirectional zero-crossing point statistical method for the outlet pressure of the metering device is as follows: with Ts as the statistical period, the outlet pressure statistically recorded in the current sampling period is P(k), the rotor position in the next statistical period is P(k+1), and the corresponding intermediate position before the disturbance is P(0). Muti(P) = (P(k) - P(0)) * (P(k+1) - P(0)); if Muti(P) < 0, then the corresponding P(k) is the zero-crossing point. Step 35: Let t0 be the zero-crossing time of the LVDT position. Starting from t0, the number of zero-crossing difference cycles N=0. Start searching for the first zero-crossing time of the metering device outlet pressure, denoted as t1. Perform N+1 operations in each sampling cycle, with a sampling period of Ts. At time t1, t1-t0=N*Ts. Let k=N, then the time difference between the zero-crossing point of a single rotor position and the zero-crossing point of the outlet pressure is k*Ts. Step 36: Each frequency point lasts for NN cycles, with a total of 2NN zero-crossing points. The time differences of the 2NN zero-crossing points are weighted and averaged to obtain the average zero-crossing time difference as kave*Ts. Step 37: Let the frequency of the current sinusoidal disturbance be f(k). The phase lag angle corresponding to this frequency point is calculated as follows: Llag(k) = kave * Ts * f(k) * 360. Step 38: Let L(k) be the zero-crossing point of the valve position. Starting from this zero-crossing point, traverse the point with the maximum amplitude of the LVDT position within (1 / f(k)) / Ts sampling periods, and denote it as Lmax(k). Take the weighted average of Lmax(k) over k sampling periods to obtain Lmaxave(k). Step 39: Let P(k) be the zero point of the outlet pressure of the metering device. Starting from this zero point, within (1 / f(k)) / Ts sampling periods, traverse the point with the maximum amplitude of the outlet pressure of the metering device, and denote it as Pmax(k). Take the weighted average of Pmax(k) for k sampling periods to obtain Pmaxave(k). Step 310: The method for calculating the amplitude ratio of the metering device outlet pressure to the LVDT position tracking is as follows: Let the sinusoidal amplitude of the metering device outlet pressure corresponding to each traversal frequency point f(k) be Pmaxave(k), and the sinusoidal amplitude of the LVDT position be Lmaxave(k); then the amplitude ratio gain K(k) corresponding to this frequency point is = Pmaxave(k) / Lmaxave(k).

10. The method according to claim 6, characterized in that, Step 4 includes: Step 41: Record the amplitude ratio K(k) and phase difference Llag(k) corresponding to each frequency point f(k). Compress the frequency coordinates according to the logarithmic representation of frequency points on the Bode plot and save the data. Step 42: Draw the Bode plot amplitude-frequency response and phase-frequency response diagrams based on the Bode plot data.

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