Guided aircraft rudder non-inductive driving vector weak magnetic control method

Abstract

The application discloses a kind of weak magnetic control methods of guided aircraft rudder machine non-inductive drive vector, uses flight control computer and rudder machine drive control system, adopts no position sensor surface-mounted permanent magnet synchronous motor vector control and weak magnetic method, help aircraft in full speed range no position sensor drive.For better adjustment rudder machine in full speed range stable operation, so that aircraft can fly quickly and stably, high-frequency injection method is used in the zero speed stage of rudder machine to start motor, extended Kalman filter state observer is used in low speed and high speed stage, rotor position and speed information are accurately calculated, and speed is expanded through weak magnetic control algorithm to meet the speed requirement of aircraft, achieve aircraft full speed range no position sensor drive, save cost, improve the stability and high speed of guided aircraft flight.

Description

Technical Field

[0001] This invention relates to the field of guided aircraft technology, specifically to a sensorless drive vector magnetic weakening control method for guided aircraft servos. Background Technology

[0002] The speed required for guided aircraft varies at different times during launch and flight. Changes and fluctuations in speed affect the precision of the guided aircraft's servo control, indirectly impacting the guidance effectiveness of the guidance system. While several methods have been implemented to improve the guidance accuracy of guided aircraft, with some success, there is still room for improvement. This is because traditional PID control methods and multi-sensor feedback systems are insufficient to meet the control requirements of high-precision guided aircraft, and many unpredictable factors in practical applications can ultimately affect the accurate guidance of the target.

[0003] Based on existing technology, there is a need for a servo motor magnetic weak drive vector control method that can precisely control guided aircraft and stabilize flight. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a sensorless drive vector magnetic weakening control method for guided aircraft servos. This method enables precise control of the guided aircraft, allowing for accurate and stable launch and flight.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0006] A sensorless vector magnetic weakening control method for a guided aircraft servo motor utilizes a flight control computer and a servo motor drive control system. The overall structure comprises a ground flight control system, data communication circuitry, flight control computer, servo motor drive circuitry, GPS and geomagnetic components, and the servo motor itself. The servo motor employs a sensorless surface-mounted permanent magnet synchronous motor as the drive motor for the guided aircraft. The flight control computer and servo motor drive controller utilize a control architecture with the DSP28335 as the core control chip.

[0007] To better adjust the servo motor to operate stably across the entire speed range and enable the aircraft to fly quickly and stably, a high-frequency injection method is used to start the motor at zero speed. An extended Kalman filter state observer is used at low and high speeds to accurately calculate rotor position and speed information. A field weakening control algorithm is used to extend the speed to meet the aircraft's speed requirements, achieving sensorless operation across the entire speed range of the aircraft. This saves costs and improves the stability and high-speed performance of the guided aircraft.

[0008] The specific steps are as follows:

[0009] S1: Design the flight control computer and servo drive controller, and build a ground-based flight simulation system;

[0010] S2: During the aircraft startup phase, a high-frequency sinusoidal wave injection method is used, that is, injecting symmetrical high-frequency pulses that will not cause the servo rotor to rotate into the coil of the permanent magnet synchronous motor. The high-frequency voltage equation and current expression of the PMSM in the dq axis coordinate system are determined. A bandpass filter is used to remove the fundamental frequency current component, thereby obtaining the current signal and modulating the current signal. A low-pass filter is used to extract the low-frequency signal of the motor rotor position estimation error angle. The rotor position is then calculated from the high-frequency response current, and the servo is driven to rotate through a vector control method.

[0011] S3: During the flight phase of the aircraft, the flight control computer continuously receives real-time attitude data through the GPS and geomagnetic combined attitude detection system. It outputs control signals to the servo motors through the aircraft aerodynamic data mathematical model and the geomagnetic / GPS fusion algorithm, so that the aircraft can fly stably on the predetermined trajectory.

[0012] S4: During the operation of the servo, the rotor position and speed information of the motor are estimated by building an extended Kalman filter state observer and fed back to the flight control computer. The flight control computer controls the speed of the servo through a PID algorithm according to the speed parameter value set by the flight control system, forming a speed loop.

[0013] S5: When the current rotational speed of the servo has not reached the flight speed set by the flight control system, but the current servo voltage has reached its maximum value, the servo is driven to speed up through the field weakening control algorithm to meet the set flight speed and shorten the flight time.

[0014] With the above design, after receiving the launch command from the ground flight control system, the flight control computer transmits the start control command to the servo controller. Through the high-frequency sine wave injection method, symmetrical high-frequency pulses that will not cause the motor rotor to rotate are injected into the coil of the permanent magnet synchronous motor. The rotor position is calculated from the high-frequency response current, and the sensorless permanent magnet synchronous motor is rotated by vector control to start the aircraft.

[0015] As a preferred embodiment of the present invention, in step S1, the hardware design of the guided aircraft servo control system and the construction of a ground-based flight simulation system are specifically as follows:

[0016] S-A1: Design of flight control computer circuit; the flight control computer uses TI's TMS320F28335 chip, and its main functional modules include: RS422 communication circuit, RS232 communication circuit, A / D acquisition module, power supply module, PWM trigger module, GPS component module, and geomagnetic component module; the flight control computer receives attitude information from the GPS component and geomagnetic component combined attitude detection system and external input speed signal commands, and sends commands to the servo driver through control algorithm;

[0017] S-A2: Designs servo drive circuits and communication circuits to facilitate servo operation and receive speed commands from the flight control computer. The servo drive controller uses the TI TMS320F28335 control chip, suitable for motor control. The main circuit modules include: optocoupler isolation circuit, PWM circuit, RS485 circuit, and RS422 circuit. The DSP's PWM signal processor can output 6 PWM signals, which are optocoupled through the control loop to enable normal operation.

[0018] As a preferred embodiment of the present invention, in step S2, the high-frequency voltage equation and current expression of the PMSM in the dq axis system are determined, the fundamental frequency current component is removed using a bandpass filter to obtain the current signal, and the current signal is amplitude modulated. A low-pass filter is used to extract the low-frequency signal of the motor rotor position estimation error angle. The main purpose of using the high-frequency sine wave injection method is to sensorlessly start the servo motor rotation, so that the aircraft can start flight; specifically:

[0019] S-B1: Establishing the high-frequency voltage equation:

[0020]

[0021] Among them, U d U q and i d i q These are the stator d-axis and q-axis high-frequency voltage and current components in the actual rotational speed synchronous reference coordinate system; L d ,L q and Ri d ,Ri q These are the stator inductance and resistance voltage drops along the d and q axes under high-frequency excitation, respectively; w e It is angular velocity, ψ f It is magnetic flux; as the frequency of the sinusoidal voltage increases, the inductive impedance also increases. When it increases to a sufficiently high level, the resistive impedance becomes negligible compared to the inductive impedance and can be omitted; at zero or low speed of the motor, w e The angular velocity is very small and can be omitted.

[0022] S-B2: Defines the rotor position error formula:

[0023]

[0024] Where θ is the actual rotor position angle. Estimate the angle for rotor position;

[0025] S-B3: Calculate the relationship between high-frequency voltage and current signals in the estimated speed synchronization reference coordinate system:

[0026]

[0027] in, These are the stator d- and q-axis high-frequency voltage and high-frequency current components in the estimated rotational speed synchronous reference coordinate system;

[0028] S-B4: Defines the average inductance as: L avg =(L d +L q ) / 2; the half-differential inductance is: L dif =(L d -L q ) / 2;

[0029] S-B5: A high-frequency voltage signal is injected onto the d-axis in the estimated rotational speed synchronous reference coordinate system. The expression for the injected high-frequency voltage signal is as follows:

[0030]

[0031] Among them, U in The amplitude of the high-frequency voltage signal;

[0032] but:

[0033]

[0034] It can be seen that if the d-axis and q-axis impedances are not equal, i.e., L dif If the value is not equal to 0, then in the estimated synchronous rotating coordinate system, the amplitudes of the high-frequency current components on both the d-axis and q-axis are related to the rotor position estimation error angle Δθ; when the rotor position estimation error angle Δθ = 0, the amplitudes of the high-frequency current components on the d-axis are related to the average inductance L. avg The q-axis high-frequency current is not equal to 0, while the q-axis high-frequency current is equal to 0. Therefore, the q-axis high-frequency current can be processed appropriately and used as the input signal of the rotor position tracking observer to obtain the rotor position and speed.

[0035] S-B6: The expression for calculating the high-frequency response current is:

[0036]

[0037] The high-frequency pulse voltage signal injection method uses a bandpass filter to filter out the fundamental frequency current component, thereby obtaining the current signal. This current signal is then amplitude modulated, and a low-pass filter is used to extract the low-frequency signal representing the motor rotor position estimation error angle. The expression is:

[0038]

[0039] in, For the input estimation signal, K h For error gain, this formula indicates that the estimated rotor angle of the motor tends to be similar to the actual angle. The principle of the high-frequency pulse voltage signal injection method is as follows: Figure 1As shown.

[0040] As a preferred embodiment of the present invention, in step S3, the flight control computer continuously receives real-time attitude data through the GPS and geomagnetic combined attitude detection system, and outputs control signals to the servo motors through the aircraft aerodynamic data mathematical model and the geomagnetic / GPS fusion algorithm, so that the aircraft can fly stably on the predetermined trajectory.

[0041] As an improvement of the present invention, in step S4, the servo motor of the guided aircraft servo control system is controlled by a surface-mounted permanent magnet synchronous motor using an extended Kalman filter observer.

[0042] A state observer is essentially a mathematical model that simulates a real controlled object, used to determine state variables that cannot be obtained through measurement. For a servo motor system, if there are no sensors to measure the motor's speed and rotor position, a state observer can be built to estimate the motor's rotor and rotor position. Specifically:

[0043] The state-space equations of a linear system are:

[0044]

[0045] Equations for permanent magnet synchronous motors:

[0046]

[0047] The above equation means that, abstracting each phase as a series connection of a resistor R, an inductor L, and a back electromotive force, the voltage of each phase is the sum of the voltage drops of the first three terms, and the back electromotive force is the velocity multiplied by the magnetic flux linkage, i.e., w. e ψ f The resistance R, inductance L, and flux linkage in the equation are inherent parameters of the motor, and the current i α i β The values ​​can be obtained through the sampling resistor, leaving only the angle θ and rotational speed w. e The motor equations are transformed into state-space expressions:

[0048]

[0049] S-C1: Confirm that the state variables are respectively The matrix representation is then:

[0050]

[0051] S-C2: The expression for the input u in the α-β coordinate system in the state-space equations is:

[0052]

[0053] The output matrix y is the current matrix measured by the sampling resistor:

[0054]

[0055] Then the H and B matrices can be represented as:

[0056]

[0057] The matrix representation at this point is:

[0058]

[0059]

[0060] For this state-space representation, the linear Ax cannot be explicitly represented because the motor system is not linear. Therefore, a nonlinear term f(x) is used instead; f(x) is defined as:

[0061]

[0062] The state-space equation then becomes:

[0063]

[0064] An extended Kalman filter can be used to handle this type of nonlinear motor system. The state-space equation f(x) is nonlinear. To perform Kalman filtering on a nonlinear system, it needs to be linearized. Taylor series expansion is one method to linearize a nonlinear system. Expanding f(x) using the Taylor series and taking the first two terms:

[0065]

[0066] Take the partial derivative of f(x):

[0067]

[0068] At this point, the state-space equations become:

[0069]

[0070] The state equations are based on continuous systems and need to be transformed into discretized systems before a Kalman filter state observer can be implemented in a microcontroller; in the discretized system, The state-space equations are then expressed as:

[0071]

[0072] x k =x k-1 +(f(xk-1 )+Bu k-1 )Δt

[0073] = (I+FΔt)x k-1 +Bu k-1 Δt

[0074] Let A = (I + FΔt), the extended Kalman filter process consists of the following five steps:

[0075] ① Calculate the estimated value

[0076]

[0077] ② Calculate the error covariance

[0078]

[0079] ③ Calculate the Kalman gain

[0080]

[0081] ④ Revised estimates

[0082]

[0083] ⑤ Update the error covariance for the next calculation.

[0084]

[0085] In the five equations above, Δt is the sampling time, Q is the model error, and R is the measurement error;

[0086] S-C3: Control Id=0, compare the speed obtained without sensors with the speed reference, and control the value of Iq through PID control;

[0087] For speed closed-loop PID control, PD control is generally used. The theoretical calculated values ​​of Kp and Kd are:

[0088]

[0089] Where β is the bandwidth of the speed loop, typically 50 rad / s; J is the moment of inertia of the motor, an inherent parameter of the motor; P is the number of pole pairs of the motor; ψ f It is the magnetic flux of the motor.

[0090] As an improvement of the present invention, in step S5, under the rated condition of the armature voltage of the servo motor, as the servo motor speed increases, the spatial rotational speed of the armature reaction magnetic field also continuously increases. When the armature voltage reaches the limit value, the speed of the servo motor is limited and cannot be increased further. However, the guided aircraft requires high speed. In order to reach the set speed value and increase the servo motor speed, the back electromotive force inside the servo motor must not exceed the rated value of the servo motor. The back electromotive force is proportional to the product of the air gap magnetic flux inside the servo motor. In order to keep the product of speed and magnetic flux constant, the air gap magnetic flux can only be reduced to ensure that the speed can be increased. In order to reduce the air gap magnetic flux and keep the back electromotive force constant, the demagnetizing effect of the direct-axis armature current can be used, which can weaken the excitation magnetic flux of the rotor.

[0091] In a preferred embodiment of the present invention, in step S5, the terminal voltage and terminal current of the motor are defined as Us and Is, respectively, and the maximum voltage and maximum current are defined as Usmax and Ismax, respectively. These two parameters are subject to the following constraints:

[0092] i s ≤I smax

[0093] U s ≤U smax

[0094] Based on the field weakening control principle of voltage regulation, the dq axis serves as the input voltage for field weakening, and its output is mainly controlled by a current loop PI regulator, where Udc is the inverter DC bus voltage; therefore:

[0095]

[0096] I d 2 +I q 2 ≤I s 2

[0097] When the motor voltage reaches its voltage limit, field weakening is necessary to redistribute the currents Id and Iq. This is achieved by comparing the magnitudes of the voltages, i.e., comparing... and The magnitude of Iq is adjusted by the angle of the integral regulator so that when the voltage is used to its maximum value, the current of Iq is distributed, so that a part of the magnetic weakening component of Id is generated, while the component of itself is reduced, and finally the magnetic weakening effect is achieved.

[0098] The technical effects of this invention are as follows: By designing a flight control computer and servo drive control system, this invention employs a sensorless surface-mounted permanent magnet synchronous motor vector control and field weakening method. It uses a high-frequency injection method to start the motor at zero speed, and an extended Kalman filter state observer to accurately calculate rotor position and speed information at low and high speeds. Furthermore, it uses a field weakening control algorithm to extend the speed range to meet the aircraft's speed requirements, achieving sensorless drive across the entire speed range of the aircraft. This saves costs, improves the precise and high-performance control of the guided aircraft, and results in stable flight. Attached Figure Description

[0099] Figure 1 This is a schematic diagram of the flight control computer circuit in this invention;

[0100] Figure 2 This is a schematic diagram of the servo drive controller circuit in this invention;

[0101] Figure 3 This is a physical image of the servo motor assembly in this invention;

[0102] Figure 4 This is a block diagram of the guided aircraft control system in this invention;

[0103] Figure 5 This is a block diagram of high-frequency injection in this invention. Detailed Implementation

[0104] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0105] A sensorless vector field weakening control method for guided aircraft servos is disclosed. This method utilizes a flight control computer and a servo drive control system, employing sensorless surface-mounted permanent magnet synchronous motor vector control and field weakening techniques to enable sensorless actuation across the entire speed range. The control flow of this method is as follows: Figure 4 As shown.

[0106] To better adjust the servo motor for stable operation across the entire speed range, enabling the aircraft to fly quickly and stably, a high-frequency injection method is used to start the motor at zero speed. During low and high speed phases, an extended Kalman filter state observer is used to accurately calculate rotor position and speed information. Furthermore, a field weakening control algorithm is employed to extend the speed range to meet the aircraft's speed requirements. This achieves sensorless operation across the entire speed range, saving costs and improving the stability and high-speed performance of the guided aircraft. The steps are as follows:

[0107] S1: Design the flight control computer circuit, servo drive circuit, and communication circuit to build a ground-based flight simulation system. For example... Figure 1 This is the schematic diagram of the flight control computer circuit. Figure 2 This is a schematic diagram of a servo motor drive circuit.

[0108] In step S1, the flight control computer uses the TI TMS320F28335 chip. Its main functional modules include: RS422 communication circuit, RS232 communication circuit, A / D acquisition module, power supply module, PWM trigger module, GPS component module, and geomagnetic component module. The flight control computer receives attitude information from the GPS and geomagnetic component combined attitude detection system and external input speed signal commands, and sends commands to the servo drivers through control algorithms.

[0109] In step S1, the servo drive controller uses the TI TMS320F28335 control chip, suitable for motor control. The main circuit modules include: optocoupler-isolated power supply, PWM circuit, RS485 circuit, and RS422 circuit. The DSP's PWM signal processor can output six PWM signals, which are optocoupled through a control loop to ensure normal operation.

[0110] S2: During the aircraft startup phase, a high-frequency sinusoidal wave injection method is used. This involves injecting symmetrical high-frequency pulses into the coils of the permanent magnet synchronous motor (PMSM) that will not cause the servo rotor to rotate. The high-frequency voltage equation and current expression of the PMSM in the dq-axis coordinate system are determined. A bandpass filter is used to remove the fundamental frequency current component, thus obtaining the current signal. This current signal is then amplitude modulated, and a low-pass filter is used to extract the low-frequency signal representing the rotor position estimation error angle. The rotor position is calculated from the high-frequency response current, and the servo is driven to rotate using a vector control method. The high-frequency injection method process is as follows: Figure 5 As shown.

[0111] Specifically:

[0112] S-B1: Establishing the high-frequency voltage equation:

[0113]

[0114] In the formula, U d U q and i d i q These are the stator d-axis and q-axis high-frequency voltage and current components in the actual rotational speed synchronous reference coordinate system; L d ,L q and Ri d ,Ri q These are the stator inductance and resistance voltage drops along the d and q axes under high-frequency excitation, respectively; w e It is angular velocity, ψ f It is magnetic flux; as the frequency of the sinusoidal voltage increases, the inductive impedance also increases. When it increases to a sufficiently high level, the resistive impedance becomes negligible compared to the inductive impedance and can be omitted; at zero or low speed of the motor, w e The angular velocity is very small and can be omitted.

[0115] S-B2: Defines the rotor position error formula:

[0116]

[0117] Where θ is the actual rotor position angle. Estimate the angle for rotor position;

[0118] S-B3: Calculate the relationship between high-frequency voltage and current signals in the estimated speed synchronization reference coordinate system:

[0119]

[0120] In the formula, These are the stator d- and q-axis high-frequency voltage and high-frequency current components in the estimated rotational speed synchronous reference coordinate system;

[0121] S-B4: Defines the average inductance as: L avg =(L d +L q ) / 2; the half-differential inductance is: L dif =(L d -L q ) / 2;

[0122] S-B5: A high-frequency voltage signal is injected onto the d-axis in the estimated rotational speed synchronous reference coordinate system. The expression for the injected high-frequency voltage signal is as follows:

[0123]

[0124] In the formula, U in The amplitude of the high-frequency voltage signal;

[0125] but:

[0126]

[0127] The above equation shows that if the impedances of the d-axis and q-axis are not equal, i.e., L dif If the value is not equal to 0, then in the estimated synchronous rotating coordinate system, the amplitudes of the high-frequency current components along the d-axis and q-axis are related to the rotor position estimation error angle Δθ. When the rotor position estimation error angle Δθ = 0, the amplitudes of the high-frequency current components along the d-axis and the average inductance L are related to the rotor position estimation error angle Δθ. avg The value is related to the fact that it is not equal to 0, while the q-axis high-frequency current is equal to 0. Therefore, the q-axis high-frequency current can be processed appropriately and used as the input signal of the rotor position tracking observer to obtain the rotor position and speed.

[0128] S-B6: The expression for calculating the high-frequency response current is:

[0129]

[0130] The high-frequency pulse voltage signal injection method uses a bandpass filter to filter out the fundamental frequency current component, thereby obtaining the current signal. This current signal is then amplitude-modulated, and a low-pass filter is used to extract the low-frequency signal representing the motor rotor position estimation error angle. The expression is shown in the equation:

[0131]

[0132] In the formula, For the input estimation signal, K h For error gain, this formula indicates that the estimated angle of the motor rotor tends to be similar to the actual angle.

[0133] S3: During the flight phase of the aircraft, the flight control computer continuously receives real-time attitude data through the GPS and geomagnetic combined attitude detection system. It outputs control signals to the servos through the aircraft's aerodynamic data mathematical model and geomagnetic / GPS fusion algorithm, enabling the aircraft to fly stably on the predetermined trajectory.

[0134] S4: During the operation of the servo, the rotor position and speed information of the motor are estimated by building an extended Kalman filter state observer and fed back to the flight control computer. The flight control computer controls the speed of the servo through a PID algorithm based on the speed value parameters set by the ground flight control system, forming a speed loop.

[0135] A state observer is essentially a mathematical model that simulates a real controlled object, used to determine state variables that cannot be obtained through measurement. For a servo motor system, if there are no sensors to measure the motor's speed and rotor position, a state observer can be built to estimate the motor's rotor and rotor position.

[0136] The state-space equations of a linear system are:

[0137]

[0138] Equations for permanent magnet synchronous motors:

[0139]

[0140] The above equation means that, abstracting each phase as a series connection of a resistor, an inductor, and a back electromotive force (EMF), the voltage of each phase is the sum of the voltage drops of the first three terms, and the back EMF is the speed multiplied by the magnetic flux linkage. The resistor R, inductor L, and magnetic flux linkage in the equation are inherent parameters of the motor. The current can be obtained through sampling resistors, leaving only the angle and speed. The motor equation can then be transformed into a state-space expression:

[0141]

[0142] S-C1: Confirm that the state variables are respectively The matrix representation is then:

[0143]

[0144] S-C2: The expression for the input u in the α-β coordinate system in the state-space equations is:

[0145]

[0146] The output matrix y is the current matrix measured by the sampling resistor:

[0147]

[0148] Then the H and B matrices can be represented as:

[0149]

[0150] The matrix representation at this point is:

[0151]

[0152]

[0153] For this state-space representation, the linear Ax cannot be explicitly represented because the motor system is not linear. Therefore, a nonlinear term f(x) is used instead; f(x) is defined as:

[0154]

[0155] The state-space equation then becomes:

[0156]

[0157] The extended Kalman filter can be used to handle this type of nonlinear motor system. The state-space equation f(x) is nonlinear. To perform Kalman filtering on a nonlinear system, it needs to be linearized. Taylor series expansion is one method to linearize a nonlinear system. Expanding f(x) using the Taylor series and taking the first two terms:

[0158]

[0159] Take the partial derivative of f(x):

[0160]

[0161] At this point, the state-space equations become:

[0162]

[0163] State equations are based on continuous systems and need to be transformed into discretized systems before a Kalman filter state observer can be implemented in a microcontroller. In discretized systems, The state-space equations are then expressed as:

[0164]

[0165] x k =x k-1 +(f(x k-1 )+Bu k-1 )Δt

[0166] = (I+FΔt)x k-1 +Bu k-1 Δt

[0167] Let A = (I + FΔt), the extended Kalman filter process consists of the following five steps:

[0168] ① Calculate the estimated value

[0169]

[0170] ② Calculate the error covariance

[0171]

[0172] ③ Calculate the Kalman gain

[0173]

[0174] ④ Revised estimates

[0175]

[0176] ⑤ Update the error covariance for the next calculation.

[0177]

[0178] In the five equations above, Δt is the sampling time, Q is the model error, and R is the measurement error.

[0179] S-C3: Control Id=0, compare the speed obtained without sensors with the speed reference, and control the value of Iq through PID.

[0180]

[0181] Where β is the bandwidth of the speed loop, typically 50 rad / s; J is the moment of inertia of the motor, an inherent parameter of the motor; P is the number of pole pairs of the motor; ψ f It is the magnetic flux of the motor.

[0182] S5: When the current rotational speed of the servo has not reached the flight speed set by the flight control system, but the current servo voltage has reached its maximum value, the servo is driven to speed up through the field weakening control algorithm to meet the set flight speed.

[0183] Under the rated armature voltage conditions of the servo motor, as the servo motor speed increases, the spatial rotational speed of the armature reaction magnetic field also continuously increases. When the armature voltage reaches its limit, the servo motor speed is restricted and cannot be increased further. However, guided aircraft require high speeds. To achieve the set speed value and increase the servo motor speed, the back electromotive force (EMF) inside the servo motor must not exceed its rated value. The back EMF is proportional to the product of the air gap magnetic flux inside the servo motor. To keep the product of speed and flux constant, the air gap flux must be reduced to ensure that the speed can be increased. To reduce the air gap flux while keeping the back EMF constant, the demagnetizing effect of the direct-axis armature current can be used, which weakens the rotor's excitation flux.

[0184] Define the motor's terminal voltage and terminal current as Us and Is, respectively, and the maximum voltage and maximum current as Usmax and Ismax, respectively. These two parameters are subject to the following constraints:

[0185] i s ≤I smax

[0186] U s ≤U smax

[0187] Based on the field weakening control principle of voltage regulation, the dq-axis serves as the input voltage for field weakening, and its output is mainly controlled by a current loop PI regulator, where Udc is the inverter's DC bus voltage. Therefore:

[0188]

[0189] I d 2 +I q 2 ≤I s 2

[0190] When the motor voltage reaches its voltage limit, field weakening is necessary to redistribute the currents Id and Iq. This is achieved by comparing the magnitudes of the voltages, i.e., comparing... and The magnitude of Iq is adjusted by the angle of the integral regulator so that when the voltage is used to its maximum value, the current of Iq is distributed, so that a part of the magnetic weakening component of Id is generated, while the component of itself is reduced, and finally the magnetic weakening effect is achieved.

[0191] 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, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A sensorless drive vector field weakening control method for a guided aircraft servo motor, characterized in that, It uses a flight control computer and servo drive control system, and adopts a sensorless surface-mounted permanent magnet synchronous motor vector control and field weakening method to help the aircraft drive without position sensors across the entire speed range. To better adjust the servo motor for stable operation across the entire speed range, enabling the aircraft to fly quickly and stably, a high-frequency injection method is used to start the motor at zero speed. During low and high speed phases, an extended Kalman filter state observer is used to accurately calculate rotor position and speed information. Furthermore, a field weakening control algorithm is employed to extend the speed range to meet the aircraft's speed requirements. This achieves sensorless operation across the entire speed range, saving costs and improving the stability and high-speed performance of the guided aircraft. The specific steps are as follows: S1: Design the flight control computer and servo drive controller, and build a ground-based flight simulation system; S2: During the aircraft startup phase, a high-frequency sinusoidal wave injection method is used. This involves injecting symmetrical high-frequency pulses into the coils of the permanent magnet synchronous motor (PMSM) that will not cause the servo rotor to rotate. The high-frequency voltage equation and current expression of the PMSM in the dq-axis coordinate system are determined. A bandpass filter is used to remove the fundamental frequency current component, thus obtaining the current signal. The current signal is then amplitude-modulated, and a low-pass filter is used to extract the low-frequency signal representing the rotor position estimation error angle. The rotor position is then calculated from the high-frequency response current, and the servo is driven to rotate using a vector control method. The high-frequency sinusoidal wave injection method includes calculating the high-frequency response current expression as follows: in, This represents the amplitude of the high-frequency voltage signal. For average inductance, It is a half-differential inductor. This refers to the rotor position error; The high-frequency pulse voltage signal injection method uses a bandpass filter to filter out the fundamental frequency current component to obtain the current signal and modulates the current signal. Then, a low-pass filter is used to extract the low-frequency signal of the motor rotor position estimation error angle. in, For the input estimated signal, This formula represents the error gain, indicating that the estimated rotor angle of the motor tends to be similar to the actual angle. S3: During the flight phase of the aircraft, the flight control computer continuously receives real-time attitude data through the GPS and geomagnetic combined attitude detection system. It outputs control signals to the servo motors through the aircraft aerodynamic data mathematical model and the geomagnetic / GPS fusion algorithm, enabling the aircraft to fly stably on the predetermined trajectory. S4: During the operation of the servo, the rotor position and speed information of the motor are estimated by building an extended Kalman filter state observer and fed back to the flight control computer. The flight control computer controls the speed of the servo through a PID algorithm according to the speed parameter value set by the flight control system, forming a speed loop. S5: When the current rotational speed of the servo motor has not reached the flight speed set by the flight control system, but the current servo motor voltage has reached its maximum value, the servo motor is driven to speed up through the field weakening control algorithm to meet the set flight speed. In step S4, the extended Kalman filter state observer is used to obtain the servo rotor position and speed information, specifically: The state-space equations of a linear system are: Equations for permanent magnet synchronous motors: The above equation means that, abstracting each phase as a series connection of a resistor R, an inductor L, and a back electromotive force, the voltage of each phase is the sum of the voltage drops of the first three terms, and the back electromotive force is the velocity multiplied by the magnetic flux linkage. The resistance R, inductance L, and flux linkage in the equation are inherent parameters of the motor, and the current... The values ​​can be obtained through the sampling resistor, leaving only the angle θ and rotational speed. The motor equations are transformed into state-space expressions: S-C1: Confirm that the state variables are respectively Then the matrix representation is: S-C2: The expression for the input u in the α-β coordinate system in the state-space equations is: The output matrix y is the current matrix measured by the sampling resistor: Then the H and B matrices can be represented as: The matrix representation at this point is: For this state-space representation, the linear Ax cannot be explicitly represented because the motor system is not linear. Therefore, a nonlinear term f(x) is used instead; f(x) is defined as: The state-space equation then becomes: This type of nonlinear motor system can be handled using an extended Kalman filter; In the state-space equation, f(x) is nonlinear. If we want to perform Kalman filtering on a nonlinear system, we need to linearize it. Taylor series expansion is one way to linearize a nonlinear system. Expanding f(x) into a Taylor series and taking the first two terms: Take the partial derivative of f(x): At this point, the state-space equations become: The state equations are based on continuous systems and need to be transformed into discretized systems before a Kalman filter state observer can be implemented in a microcontroller; in the discretized system, Then the state-space equation can be expressed as: Let A = (I + F) The extended Kalman filter process consists of the following five steps: ① Calculate the estimated value ② Calculate the error covariance ③ Calculate Kalman gain ④ Revised estimates ⑤ Update the error covariance for the next calculation. In the five equations above, Δt is the sampling time, Q is the model error, and R is the measurement error; S-C3: Control Id=0, compare the speed obtained without sensors with the speed reference, and control the value of Iq through PID control; Where β is the bandwidth of the speed loop, typically 50 rad / s; J is the moment of inertia of the motor, an inherent parameter of the motor; and P is the number of pole pairs of the motor. It is the magnetic flux of the motor.

2. The sensorless drive vector field weakening control method for a guided aircraft servo motor according to claim 1, characterized in that, In step S1, the flight control computer circuit, servo drive circuit, and communication circuit are designed to build a ground-based flight simulation system. The flight control computer uses the TMS320F28335 chip from TI. Its main functional modules include: RS422 communication circuit, RS232 communication circuit, A / D acquisition module, power supply module, PWM trigger module, GPS component module, and geomagnetic component module. The flight control computer receives attitude information from the GPS component and geomagnetic component combined attitude detection system and external input speed signal commands, and sends commands to the servo drive through the control algorithm. The servo drive controller uses the TMS320F28335 control chip from TI and is suitable for motor control. Its main circuit modules include: optocoupler isolation circuit, PWM circuit, RS485 circuit, and RS422 circuit. The DSP's PWM signal processor can output 6 PWM signals, which are optocoupled through the control loop to enable normal operation.

3. The sensorless drive vector field weakening control method for a guided aircraft servo motor according to claim 1, characterized in that, In step S2, the primary purpose of using the high-frequency sine wave injection method is to seamlessly initiate the rotation of the servo motor, thereby enabling the aircraft to take off; specifically: S-B1: Establishing the high-frequency voltage equation: in, , and , These are the stator d and q axis high-frequency voltage and high-frequency current components in the actual rotational speed synchronous reference coordinate system; , and , These are the stator inductance and resistance voltage drops on the d and q axes, respectively, under high-frequency excitation. It's angular velocity. It's the magnetic flux linkage; as the frequency of the sinusoidal voltage increases, the inductive impedance also increases. When it increases high enough, the resistive impedance becomes negligible compared to the inductive impedance and can be omitted; at zero or low speed of the motor... The angular velocity is very small and can be omitted. S-B2: Defines the rotor position error formula: Where θ is the actual rotor position angle. Estimate the angle for rotor position; S-B3: Calculate the relationship between high-frequency voltage and current signals in the estimated speed synchronization reference coordinate system: in, These are the stator d- and q-axis high-frequency voltage and high-frequency current components in the estimated rotational speed synchronous reference coordinate system; S-B4: Defines the average inductance as: = / 2; The half-difference inductance is: / 2; S-B5: A high-frequency voltage signal is injected onto the d-axis in the estimated rotational speed synchronous reference coordinate system. The expression for the injected high-frequency voltage signal is as follows: in, The amplitude of the high-frequency voltage signal; but: It can be seen that if the impedances of the d-axis and q-axis are not equal, that is... In the estimated synchronous rotating coordinate system, the amplitudes of the high-frequency current components along the d-axis and q-axis are related to the rotor position estimation error angle. Related to; when the rotor position estimation error angle When =0, the d-axis high-frequency current and average inductance The value is related to the fact that it is not equal to 0, while the q-axis high-frequency current is equal to 0. Therefore, the q-axis high-frequency current can be processed appropriately and used as the input signal of the rotor position tracking observer to obtain the rotor position and speed.

4. The sensorless drive vector field weakening control method for a guided aircraft servo motor according to claim 1, characterized in that, In step S3, the flight control computer continuously receives real-time attitude data through the GPS and geomagnetic combined attitude detection system, and outputs control signals to the servo motors through the aircraft aerodynamic data mathematical model and the geomagnetic / GPS fusion algorithm, so that the aircraft can fly stably on the predetermined trajectory.

5. The sensorless drive vector field weakening control method for a guided aircraft servo motor according to claim 1, characterized in that, In step S5, under the rated armature voltage of the servo motor, as the servo motor speed increases, the spatial rotational speed of the armature reaction magnetic field also continuously increases. When the armature voltage reaches its limit, the servo motor speed is limited and cannot be increased further. However, the guided aircraft requires high speed. To achieve the set speed value and increase the servo motor speed, the back electromotive force inside the servo motor must not exceed the rated value of the servo motor. The back electromotive force is proportional to the product of the air gap magnetic flux inside the servo motor. To keep the product of speed and magnetic flux constant, the air gap flux can only be reduced to ensure that the speed can be increased. To reduce the air gap magnetic flux and keep the back electromotive force constant, the demagnetizing effect of the direct-axis armature current can be used, which can weaken the excitation magnetic flux of the rotor.

6. The sensorless drive vector field weakening control method for a guided aircraft servo motor according to claim 5, characterized in that, In step S5, the terminal voltage and terminal current of the motor are defined as Us and Is, respectively, and the maximum voltage and maximum current are defined as Usmax and Ismax, respectively. These two parameters are subject to the following constraints: Based on the field weakening control principle of voltage regulation, the dq axis serves as the input voltage for field weakening, and its output is mainly controlled by a current loop PI regulator, where Udc is the inverter DC bus voltage; therefore: When the motor voltage reaches its voltage limit, field weakening is required to redistribute the currents Id and Iq; this is done by comparing the magnitudes of the voltages, i.e., comparing... and The magnitude of Iq is adjusted by the angle of the integral regulator so that when the voltage is used to its maximum value, the current of Iq is distributed, so that a part of the magnetic weakening component of Id is generated, while the component of itself is reduced, and finally the magnetic weakening effect is achieved.

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