Dual-motor synchronous coordination control method suitable for electric helicopter

Abstract

The invention provides a dual-motor synchronous coordination control method of an electric helicopter, which comprises the following steps: taking a first controller as a main control motor driving system, and establishing a rotor rotating speed reference by adopting a rotating speed loop control strategy; and the second controller serves as a slave control motor driving system, a torque loop control strategy is adopted, and load disturbance is estimated and compensated in real time through the extended state observer. According to the dual-redundancy motor driving system, mechanical coupling interference is effectively inhibited, the fault tolerance of the system is enhanced, a feasible technical scheme is provided for safe flight of the electric helicopter, and the dual-redundancy motor driving system has important application value.

Description

TECHNICAL FIELD

[0001] The application discloses the technical field of motor control of new energy electric helicopter, and particularly relates to a double-motor synchronous coordination control method suitable for an electric helicopter. BACKGROUND

[0002] Traditional helicopters usually rely on fuel to provide power for them, have the defects of high noise, high emission, high operation and maintenance cost, and the traditional power system has limitations in coping with large inertia load driving, dynamic response optimization and energy efficiency collaborative control, which seriously restricts its development. As a new type of green and pollution-free aircraft, the electric helicopter has been widely concerned due to its many advantages such as zero emission, low noise, low operating cost and fast dynamic response. Traditional helicopters usually rely on a single power system to provide power for them, and when the power system fails, it will directly lead to the loss of helicopter power, endangering the flight safety of the helicopter, and even causing a crash accident. Under this background, in order to avoid the situation that the loss of helicopter power occurs when the single power system of the helicopter fails, a double-motor driving system suitable for the electric helicopter is proposed to provide power for the helicopter in the form of coaxial series driving of two sets of electric driving systems. Due to its significant advantages in power split, dynamic compensation and fault-tolerant control, it has become a frontier research direction in the current field. In the motor driving system of the electric helicopter, the double-motor driving system is usually used to provide redundant power backup to increase the reliability and fault-tolerant capability of the system. Each motor driving system is composed of a motor and a controller, and according to the power demand of the electric helicopter under the actual flight condition, the two systems jointly provide power for the helicopter. The double-motor driving system of the electric helicopter not only needs to realize efficient energy transmission in the normal working state, but also needs to cope with the dynamic coupling disturbance caused by the load change in the flight process, air disturbance and other factors, and the synchronous precision control of the double motors becomes a key factor affecting the performance. SUMMARY

[0003] In view of this, the application discloses a double-motor synchronous coordination control method of an electric helicopter, which improves the synchronous control precision of the double motors.

[0004] The technical scheme provided by the application is a double-motor synchronous coordination control method of an electric helicopter, which comprises the following steps:

[0005] The first controller is used as a master motor driving system, a speed loop control strategy is adopted, and a rotor speed reference is established;

[0006] The second controller is used as a slave motor driving system, a torque loop control strategy is adopted, and a load disturbance is estimated and compensated in real time through an extended state observer;

[0007] Preferably, the rotor speed reference comprises:

[0008] S11: The two-phase current sensor installed on the first controller collects the two-phase current of the motor , which is Clarke transformed to obtain the alternating current of the motor in the two-phase static coordinate system ;

[0009] (1)

[0010] S12: The alternating current in the two-phase static coordinate system is Park transformed to obtain the direct current of the stator in the two-phase rotating coordinate system and :

[0011] (2)

[0012] wherein, is the rotor rotation angle of the main control motor (1);

[0013] S13: The speed setting device sets the speed , and the main control motor tracks the set speed through the PI controller to generate the q-axis current instruction , which is expressed as:

[0014] (3)

[0015] wherein, is the difference between the given speed and the feedback speed; t is the integral time; k p1 is the proportional coefficient of the first controller, k i1 is the integral coefficient of the first controller;

[0016] S14: The current and the direct current of the stator in the two-phase rotating coordinate system are compared to obtain , the direct current of the stator in the two-phase rotating coordinate system is obtained through the proportional integral PI2 module :

[0017] (7)

[0018] wherein, and are the proportional gains of the d-axis and the q-axis, and are the integral gains of the d-axis and the q-axis, is the permanent magnet flux linkage of the motor, is the d-axis inductance of the motor 1, is the q-axis inductance of the motor 1, is the rotational angular velocity of the first motor (1);

[0019] S15: the voltage in the d-q coordinate system 、 is obtained by Park inverse transformation, and two-phase voltage of the motor in the two-phase stationary coordinate system and are obtained:

[0020] (8)

[0021] 、 The six-phase PWM pulses required by the inverter are obtained through the SVPWM module, and the inverter outputs three-phase alternating current to drive the master motor to rotate.

[0022] The k p1 and k i1 are obtained by the following process:

[0023] The open-loop transfer function of the speed loop is:

[0024] (4)

[0025] The transfer function of a typical type II system is represented as:

[0026] (5)

[0027] where K is the open-loop gain, τ is the delay time, s is the complex frequency, T is the time constant of the system, J is the moment of inertia, p is the number of stator pole pairs, is the permanent magnet flux linkage of the motor;

[0028] The medium frequency width h with a slope of -20 dB / sec is defined, and when the medium frequency width h=5, the dynamic following performance of the PMSM is optimal. According to the principle of minimum peak value of the closed-loop amplitude-frequency characteristic, the values of k p1 and k i1 are obtained;

[0029] (6).

[0030] The torque loop control strategy in S2 includes:

[0031] S21: The two-phase current of the slave motor (2) is collected by the phase current sensor on the controller, and the current in the two-phase stationary coordinate is obtained by Clarke transformation;

[0032] (9)​

[0033] Current in two-phase stationary coordinates Two-phase current in two-phase rotating coordinates obtained by Park transformation and :

[0034] (10)

[0035] where, is the rotor rotation angle of the controlled motor (2);

[0036] S22: DC stator current in two-phase rotating coordinates obtained by expanding state observer to offset load disturbance and mechanical coupling, i q2 *current, i q2 *current and feedback current after comparison, obtained by proportional integral PI1 module feedback current obtained by proportional integral PI2 module where, and may be represented as:

[0037] (38)

[0038] where, and are the proportional gains of d-axis and q-axis, and are the integral gains of d-axis and q-axis, is the d-axis inductance of the controlled motor, is the q-axis inductance of the controlled motor, is the rotation angular velocity of the controlled motor;

[0039] S23: the voltage in d-q coordinates is obtained by Park inverse transformation in α-β coordinates and ;

[0040] Rotating coordinate system is converted into two stationary coordinate systems

[0041] (39)

[0042] where , is the two-phase voltage of the controlled motor in α-β coordinates, , is the voltage in d-q coordinates;

[0043] , The six-phase PWM pulses required by the inverter are obtained through the SVPWM module, and the inverter outputs three-phase alternating current to drive the controlled motor to rotate.

[0044] Preferably, the extended state observer estimates and compensates disturbances in real time, including:

[0045] The extended state observer regards the load disturbance and mechanical coupling effect as the extended state variables of the system;

[0046] The augmented state equation is constructed to obtain the state estimation value;

[0047] According to the error feedback between the state estimation value and the actual measurement value, the gain parameters of the extended state observer are dynamically adjusted, so that the disturbance estimation error quickly converges to zero, and the disturbance value is estimated;

[0048] The disturbance value is superimposed on the torque command through feedforward compensation to actively offset the dynamic coupling effect between the two motors and the external load disturbance.

[0049] Preferably, the recursive least squares method is used in the torque loop control strategy to identify motor parameters online:

[0050] By continuously collecting real-time data pairs of current and torque, an optimization objective of minimizing error sum of squares is constructed;

[0051] The torque coefficient estimation value is dynamically updated using a recursive algorithm. When new data is received, the parameter estimation is corrected according to the prediction error and gain coefficient;

[0052] An accurate current-torque mapping model is established based on the accurate torque coefficient identified, and the consistency of the output torque of the two motors is ensured according to the torque synchronous control law. According to the proportional relationship between the torque coefficients of the master and slave motors and the proportional integral adjustment of the torque error, the current command of the second motor is dynamically generated.

[0053] Preferably, the electromagnetic torque of the controlled motor The reference torque is tracked And the disturbance is estimated by feedforward compensation To offset the load disturbance and mechanical coupling effect:

[0054] (11)

[0055] Where, is the torque command, is the reference torque, is the load disturbance;

[0056] (12)

[0057] Where B is the damping coefficient;

[0058] To estimate the load disturbance d, the load disturbance d is regarded as an extended state z = d, whose derivative is assumed to be with the speed as state variable, the system dynamics are:

[0059] (13)

[0060] The standard form is:

[0061] (14)

[0062] where:

[0063] (15)

[0064] The augmented state equation is:

[0065] (16)

[0066] The extended state observer ESO estimates the state x and the disturbance z, with the estimated values and The ESO dynamics equation is:

[0067] (17)

[0068] where, , , .

[0069] Substitute the parameters:

[0070] (18)

[0071] Define the estimation error: , and the disturbance error: ;

[0072] (19)

[0073] Substitute the parameters:

[0074] (20)

[0075] The disturbance error dynamics are:

[0076] (21)

[0077] The error system is:

[0078] (22)

[0079] If =0, the characteristic polynomial is:

[0080] (23)

[0081] Selecting the gain , The characteristic polynomial is:

[0082] (24)

[0083] The eigenvalue is s=-ω0 (a double root), which ensures the ESO is stable and the convergence speed is adjusted by ω0;

[0084] Defining the torque coefficient Then: .

[0085] Preferably, K is estimated online using the least squares method, collecting data pairs (iq(k), Te(k)), the goal being to minimize the sum of squared errors:

[0086] (25)

[0087] The estimate is:

[0088] (26)

[0089] The flux estimate is:

[0090] (27)

[0091] Construct a Lyapunov function:

[0092] (28)

[0093] Differentiating it gives:

[0094] (29)

[0095] Substituting , , , , into (29) gives:

[0096] (30)

[0097] Let eliminate the cross terms:

[0098] (31)

[0099] Since , 、 、 >0, and >0, so The system is globally asymptotically stable.

[0100] To ensure the consistency of the torque of the two motors, the auxiliary motor current command i q2 *:

[0101] (32)

[0102] The second motor electromagnetic torque satisfies:

[0103] (33)

[0104] Assuming that the current loop response speed is much higher than the torque loop, it can be approximated that iq2=i q2 * Substituting (32) into (33) can obtain:

[0105] (34)

[0106] Thus, we can obtain:

[0107] (35)

[0108] The system closed-loop characteristic equation is: (36)

[0109] The equation corresponds to a standard second-order system: (37)

[0110] Wherein: the natural frequency , , is the damping ratio.

[0111] From which the parameter formula is derived: , .

[0112] Preferably, the master motor drive system and the master motor drive system communicate in real time through the CAN bus, and the master motor is responsible for speed control under normal working conditions, and the slave motor performs torque following.

[0113] When the master motor fails, the slave motor automatically switches from torque control mode to speed control mode, and suppresses the overshoot oscillation in the mode switching process through an adaptive parameter adjustment strategy.

[0114] The application provides a dual-motor synchronous coordination control method for an electric helicopter, and improves the safety of a motor drive system of the electric helicopter, wherein a rotor speed reference is set through speed loop control of a main motor drive system, an extended state observer is embedded in a slave motor in a torque loop, unknown disturbances are estimated in real time and mechanical coupling torque is compensated through feedforward control, and a closed loop system is constructed based on Lyapunov stability theory. Meanwhile, a current-torque mapping model is established by using a least square parameter identification method, and a torque synchronous control law is designed to ensure that the output torques of the dual motors are consistent. In addition, a dual-redundancy coordination control strategy is adopted: in normal operation, the slave motor drive system cooperates with the main motor in a torque control mode; in case of failure, the slave motor drive system automatically switches to independent speed loop control and maintains stable operation by combining adaptive PI parameter adjustment. In terms of control strategy details, the main motor drive system tracks the speed by a PI controller and generates a q-axis current reference instruction, the slave motor drive system estimates disturbances by an ESO and compensates, and the control switching under failure is realized by using a CAN bus. Under normal conditions, the dual motor drive system can quickly reach the given speed and stably operate, the current amplitudes are the same and the power is evenly distributed; in case of failure of the main motor drive system, the slave motor drive system can quickly switch the control mode, and the stable speed is restored after a short oscillation; and the high-power dynamic demand can also be met in the take-off and climb phase.

[0115] In conclusion, the dual-redundancy motor drive method effectively suppresses mechanical coupling interference and enhances system fault tolerance, and provides a feasible technical solution for safe flight of the electric helicopter, and has important application value.

[0116] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the disclosure of the application. BRIEF DESCRIPTION OF DRAWINGS

[0117] The drawings herein are incorporated into the specification and form a part of the specification, show embodiments consistent with the application, and together with the specification serve to explain the principles of the application.

[0118] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiment or prior art description will be briefly introduced below, and obviously, other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0119] Figure 1 The main controller structure control block diagram in the dual-motor synchronous coordination control method for an electric helicopter provided by the disclosed embodiment of the application;

[0120] Figure 2 The control block diagram of a slave controller in the dual-motor synchronous coordination control method for an electric helicopter provided by the disclosed embodiment of the application;

[0121] Figure 3 The control flow diagram of the main controller in the dual-motor synchronous coordination control method of the electric helicopter provided by the disclosed embodiment is shown in the figure.

[0122] Figure 4 The control flow diagram of the slave controller in the dual-motor synchronous coordination control method of the electric helicopter provided by the disclosed embodiment is shown in the figure. DETAILED DESCRIPTION

[0123] The exemplary embodiments will be described in detail herein with reference to the accompanying drawings. In the following description, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments are not representative of all embodiments consistent with the present invention. Rather, they are merely examples of systems consistent with some aspects of the present invention as detailed in the appended claims.

[0124] The electric helicopter adopts a master-slave dual-motor drive system to provide power, but the dynamic coupling interference in the system directly threatens flight safety, and the traditional single-motor drive has limitations in high inertia load, dynamic response, etc. The dual-motor drive system has many problems in power distribution, fault tolerance, etc.

[0125] The present application provides a dual-motor synchronous coordination control method for an electric helicopter. The control method adopts a speed-torque dual-loop coordination control architecture based on dynamic decoupling. The dual-motor synchronous coordination control block diagram is shown in Figure 1 The main controller 1 adopts a speed loop control strategy as the main control motor drive system. Two-phase current signals of the main motor 1 are collected through a phase current sensor. AC current in a three-phase stationary coordinate system is converted into DC components in a two-phase rotating coordinate system through Clarke transformation and Park transformation. The main motor tracks the set speed through a proportional integral controller and generates a q-axis current instruction to establish a rotor speed reference for the entire system.

[0126] The slave controller 2 adopts a torque loop control strategy as the slave control motor drive system. The core innovation is to embed an extended state observer to realize real-time estimation and compensation of disturbances. The observer regards load disturbances and mechanical coupling effects as extended state variables of the system. By constructing an augmented state equation, using the error feedback between the state estimation value of the observer and the actual measurement value, and dynamically adjusting the observer gain parameters, the disturbance estimation error converges to zero quickly. The estimated disturbance value is directly superimposed into the torque instruction through feedforward compensation, thereby actively canceling the dynamic coupling effect between the dual-motors and the external load disturbance.

[0127] Meanwhile, the online identification of motor parameters is realized by using the recursive least square method, real-time data pairs of current and torque are continuously collected to construct an optimization objective of minimizing error sum of squares, the recursive algorithm is used to dynamically update the torque coefficient estimate, the parameter estimate is corrected according to the prediction error and gain coefficient every time new data arrives, the recursive update of the covariance matrix ensures the convergence of the algorithm, the accurate torque coefficient obtained through identification is used to establish a high-precision current-torque mapping model, and a torque synchronous control law is designed to ensure the consistency of the output torque of the double motors, and the current command of the motor is dynamically generated according to the proportional relationship between the master-slave motor torque coefficients and the proportional-integral adjustment of the torque error;

[0128] In terms of fault tolerance, real-time communication between the master and slave controllers is realized through the CAN bus, the master motor is responsible for speed control and the slave motor is responsible for torque following under normal working conditions, when the master motor fault is detected, the slave motor can automatically switch from torque control mode to speed control mode, and the overshoot oscillation in the mode switching process is inhibited through an adaptive parameter adjustment strategy, thereby ensuring the flight safety of the electric helicopter in emergency situations.

[0129] The double-motor synchronous coordination control method of the electric helicopter specifically includes the following steps:

[0130] Step 1: The controller 1 adopts speed loop control, and the control block diagram is as shown in Figure 1 Two-phase current of the motor is collected through the phase current sensor installed on the controller , and is obtained through Clarke transformation.

[0131] (1)

[0132] wherein, is the two-phase phase current of the motor, is the alternating current of the motor in the two-phase stationary coordinate system.

[0133] Step 2: The alternating current in the two-phase stationary coordinate system is obtained through Park transformation to obtain the direct-current stator current and in the two-phase rotating coordinate system:

[0134] (2)

[0135] wherein, is the rotor rotation angle of the motor 1.

[0136] Step 3: The master motor tracks the set speed through a PI controller to generate the q-axis current command , which can be represented as:

[0137] (3)

[0138] in, The difference between the given speed and the feedback speed; t is the integration time; k p1 k is the proportional coefficient of controller 1. i1 is the integral coefficient of controller 1.

[0139] The parameter k of the PI controller for the speed loop p1 and k i1 Tuning can be transformed into parameter tuning for a typical Type II system. The open-loop transfer function of the speed loop is calculated and compared with the transfer function of the typical Type II system. The parameter values ​​of the open-loop transfer function of the speed loop corresponding to the optimal dynamic performance of the typical Type II system are calculated, thereby deriving the parameter k of the PI controller for the corresponding speed outer loop. p1 and k i1 The value of .

[0140] Its transfer function G(s) can be expressed as:

[0141] (4)

[0142] The transfer function of a typical Type II system can be expressed as:

[0143] (5)

[0144] Where K is the open-loop gain, τ is the hysteresis time, s is the complex frequency, T is the system time constant, J is the moment of inertia, and p is the number of stator pole pairs. For permanent magnet flux linkage in motors.

[0145] In a typical Type II system, the intermediate frequency bandwidth with a slope of -20 dB / sec is defined as h. When the intermediate frequency bandwidth h = 5, the dynamic tracking performance of the PMSM is optimal. According to the principle of minimizing the peak value of the closed-loop amplitude-frequency response, we know that k p1 and k i1 value

[0146] (6)

[0147] Step 4: Current and feedback The current is compared and then obtained through the proportional-integral (PI1) module. ,feedback The current is obtained through a proportional-integral (PI2) module. :

[0148] (7)

[0149] in, and Kd, Kq are proportional gains for d and q axes, and Kid, Kiq are integral gains for d and q axes, ψpm is the permanent magnet flux linkage of the motor, Ld is the d-axis inductance of the motor 1, Lq is the q-axis inductance of the motor 1, ω is the rotational angular velocity of the motor 1.

[0150] Step 5: the voltage in d-q coordinate system is transformed by Park inverse transformation to obtain in the two-phase stationary coordinate system and :

[0151] (8)

[0152] wherein, , are the two-phase voltages of the motor in the two-phase stationary coordinate system, , are the voltages in the two-phase rotating coordinate system.

[0153] , the six-phase PWM pulses required by the inverter are obtained through the SVPWM module, and the inverter outputs three-phase alternating current to drive the main control motor 1 to rotate.

[0154] Step 6: the controller 2 adopts torque loop control, and its control block diagram is shown in Figure 2 , first, the two-phase currents of the motor 2 are collected by the phase current sensor installed on the controller , and then the Clarke transformation is performed to obtain .

[0155] (9)

[0156] wherein, are the two-phase currents of the motor; are the currents of the motor in the two-phase stationary coordinate system, respectively.

[0157] Step 7: the currents in the two-phase stationary coordinate system are transformed by Park transformation to obtain the two-phase currents in the two-phase rotating coordinate system and :

[0158] (10)

[0159] wherein, is the rotational angle of the rotor of the motor 2.

[0160] The least square parameter identification algorithm dynamically optimizes the current-torque mapping model, accurately quantifies the nonlinear relationship between current and torque, and keeps the output torque deviation of the dual-motor system at a very low level. Based on the PI regulation of the torque synchronization control law, the motor current command is corrected in real time to ensure balanced power distribution between the master and slave motors

[0161] Step 8: In the dual-motor system, motor 2 uses torque loop control, aiming to make the electromagnetic torque of the slave motor Track the reference torque And estimate the disturbance by feedforward compensation Counteract the effects of load disturbance and mechanical coupling.

[0162] (11)

[0163] Where, is the torque command, is the reference torque, is the load disturbance.

[0164] (12)

[0165] Where B is the damping coefficient.

[0166] The slave motor drive system estimates unknown disturbances such as mechanical coupling torque and load disturbance in real time through ESO, and the feedforward compensation mechanism directly counteracts the dynamic coupling effect between the dual-motor system, solving the problem of speed fluctuation and efficiency decline caused by coupling in traditional systems. The master-slave dual-loop decoupling structure separates speed and torque control, reduces cross interference, and improves dynamic response speed.

[0167] To estimate the load disturbance d, it is considered as an extended state z = d, and its derivative is assumed to be , the speed is taken as the state variable, and the system dynamics are:

[0168] (13)

[0169] The standard form is:

[0170] (14)

[0171] Where:

[0172] (15)

[0173] Augmented state equation:

[0174] (16)

[0175] ESO estimates the state x and disturbance z, and the estimated values are and The ESO dynamic equation is:

[0176] (17)

[0177] where, , , .

[0178] Substitute the parameters:

[0179] (18)

[0180] Define the estimation error: , the disturbance error: .

[0181] (19)

[0182] Substitute the parameters:

[0183] (20)

[0184] The disturbance error dynamic:

[0185] (21)

[0186] The error system is:

[0187] (22)

[0188] If =0, the characteristic polynomial is:

[0189] (23)

[0190] Select the gain , so that the characteristic polynomial is:

[0191] (24)

[0192] The characteristic root is s=-ω0 (multiple root), which ensures the stability of the ESO and the convergence speed is adjusted by ω0.

[0193] Define the torque coefficient , then: To improve accuracy, use the least squares method to estimate K online, collect data pairs (i q (k), T e (k)), the goal is to minimize the sum of squared errors:

[0194] (25)

[0195] Estimation value:

[0196] (26)

[0197] Flux linkage estimation:

[0198] (27)

[0199] Construct Lyapunov function:

[0200] (28)

[0201] Derivation can get:

[0202] (29)

[0203] Substitute , , , , into (29):

[0204] (30)

[0205] Let Eliminate cross terms:

[0206] (31)

[0207] Since , , , > 0, and > 0, so The system is globally asymptotically stable.

[0208] To ensure the torque consistency of the dual-motor, the auxiliary motor current command i q2 *:

[0209] (32)

[0210] From the motor electromagnetic torque:

[0211] (33)

[0212] Assuming the current loop response speed is much higher than the torque loop, it can be approximated that iq2=i q2 * Substitute (32) into (33) to get:

[0213] (34)

[0214] Thus we have:

[0215] (35)

[0216] The closed loop characteristic equation of the system is: (36)

[0217] This equation corresponds to a standard second order system: (37)

[0218] Where: natural frequency , , Damping ratio.

[0219] From which the parameter formula is derived: , .

[0220] Step 9: Current loop PI regulator:

[0221] i q2 * Current and feedback After comparison, the current obtained by the proportional integral PI1 module is , feedback The current obtained by the proportional integral PI2 module is , where and Can be expressed as:

[0222] (38)

[0223] Where and Are the proportional gain of d-axis and q-axis, and Are the integral gain of d-axis and q-axis, Ld is the d-axis inductance of motor 2, Lq is the q-axis inductance of motor 2, ω is the rotational speed of motor 2

[0224] Step 10: The voltage in the d-q coordinate system is converted by Park inverse transformation to obtain The voltage in the α-β coordinate system is and .

[0225] The rotating coordinate system is converted to two static coordinate systems

[0226] (39)

[0227] Where , Are the two-phase voltages of the motor in the α-β coordinate system, , Vd, Vqare the voltage in d-q coordinate system.

[0228] The six-phase PWM pulses required by the inverter are obtained through the SVPWM module, and the inverter outputs three-phase alternating current to drive the motor 2 to rotate.

[0229] The embodiment adopts a dual-redundancy architecture to realize "one master and one slave". When the master motor drive system fails, the slave motor drive system can seamlessly switch from torque control mode to speed control mode, and the speed quickly stabilizes to the target value after a short oscillation, thereby ensuring the continuity of power in emergency situations. During the fault switching process, the adaptive PI parameter adjustment suppresses overshoot, thereby avoiding the risk of power interruption caused by mode conversion.

[0230] Under normal working conditions, the power of the two motors is evenly divided, thereby avoiding single motor overload and reducing unit power consumption. The software redundancy design does not require additional hardware to achieve fault replacement through algorithms, thereby reducing the cost of hardware redundancy solutions. The integration of CAN bus communication realizes data interaction and mode switching of the master and slave motors, is compatible with the existing helicopter control system architecture, and is convenient for engineering integration.

[0231] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the art, several improvements and modifications can be made without departing from the technical principles of the present application, and these changes and modifications should also be considered as the protection scope of the present application.​

Claims

1. A method for synchronous and coordinated control of dual motors in an electric helicopter, characterized in that, Includes the following steps: The first controller is used as the main control motor drive system, and a speed loop control strategy is adopted to establish a rotor speed reference. The second controller is used as a slave motor drive system, and a torque loop control strategy is adopted. The load disturbance is estimated and compensated in real time by an extended state observer.

2. The method for synchronous and coordinated control of dual motors in an electric helicopter according to claim 1, characterized in that, The rotor speed reference includes: S11: The phase current sensor installed on the first controller collects the two-phase current of the motor. The alternating current of the motor in a two-phase stationary coordinate system is obtained through Clarke transformation. ; （1） S12: Alternating current in a two-phase stationary coordinate system After Park transformation, the DC stator current in two-phase rotating coordinates is obtained. and : （2） in, The rotor rotation angle of the main control motor (1); S13: Speed ​​setting device sets the speed. The main control motor tracks the set speed through a PI controller. Generate q-axis current command , is represented as: （3） in, The difference between the given speed and the feedback speed; t is the integration time; k p1 k is the proportional coefficient of the first controller. i1 The integral coefficient of the first controller; S14: Current and DC stator current in two-phase rotating coordinates After comparison, the result was obtained through the proportional-integral (PI1) module. DC stator current in two-phase rotating coordinates Obtained via the proportional-integral (PI2) module : （7） in, and The proportional gain for the d-axis and q-axis, and The integral gain along the d-axis and q-axis. For permanent magnet flux linkage in motors, The d-axis inductance of motor 1 For the 1q axis inductance of the motor, Let be the rotational angular velocity of the first motor (1); S15: The voltage in the dq coordinate system , After Park inverse transform, the motor's position is obtained. Two-phase voltage in a two-phase stationary coordinate system and : （8） , The inverter obtains the six-phase PWM pulses required by the SVPWM module, and outputs three-phase AC power to drive the main control motor to rotate.

3. The method for synchronous and coordinated control of dual motors in an electric helicopter according to claim 2, characterized in that, The k p1 and k i1 It is obtained through the following process: The open-loop transfer function of the speed loop is: （4） The typical transfer function of a Type II system is expressed as: （5） Where K is the open-loop gain, τ is the hysteresis time, s is the complex frequency, T is the system time constant, J is the moment of inertia, and p is the number of stator pole pairs. For permanent magnet flux linkage in motors; Define the intermediate frequency bandwidth (IF) with a slope of -20 dB / sec as h. The PMSM exhibits optimal dynamic tracking performance when the IF bandwidth h = 5. Based on the principle of minimizing the peak value of the closed-loop amplitude-frequency response, we obtain k. p1 and k i1 The value; （6）。 4. The method for synchronous and coordinated control of dual motors in an electric helicopter according to claim 1, characterized in that, The torque loop control strategy described in S2 includes: S21: The phase current sensor on the controller collects the two-phase current of the slave motor (2). After Clarke transformation, the current in two-phase stationary coordinates is obtained. ; （9） Current in two-phase stationary coordinates Two-phase currents in two-phase rotating coordinates obtained by Park transformation and : （10） in, The rotor rotation angle of the slave motor (2); S22: DC stator current in two-phase rotating coordinate system By offsetting load disturbances and mechanical coupling through an extended state observer, i is obtained. q2 *Current, i q2 *Current and Feedback The current is compared and then obtained through the proportional-integral (PI1) module. ,feedback The current is obtained through a proportional-integral (PI2) module. ,in, and They can be represented as: （38） in, and The proportional gain for the d-axis and q-axis, and The integral gain along the d-axis and q-axis. For the d-axis inductance of the slave motor, For the q-axis inductance of the slave motor, The rotational angular velocity of the slave motor; S23: Obtain the voltage in the dq coordinate system through the inverse Park transform. coordinate system and ; Transformation of a rotating coordinate system into two stationary coordinate systems （39） in , Let the two-phase voltage of the slave motor be defined in the α-β coordinate system. , The voltage is in the dq coordinate system; , The inverter obtains the six-phase PWM pulses required by the SVPWM module, and outputs three-phase AC power to drive the slave motor to rotate.

5. The method for synchronous coordinated control of dual motors in an electric helicopter according to claim 1, characterized in that, The extended state observer performs real-time estimation and compensation for disturbances, including: The extended state observer treats load disturbances and mechanical coupling effects as extended state variables of the system; Construct the augmented state equations to obtain the state estimates; Based on the error feedback between the state estimate and the actual measurement, the gain parameter of the extended state observer is dynamically adjusted so that the disturbance estimation error quickly converges to zero, and the disturbance value is estimated. The disturbance value is superimposed on the torque command through feedforward compensation to actively counteract the dynamic coupling effect between the two motors and external load disturbances.

6. The method for synchronous coordinated control of dual motors in an electric helicopter according to claim 1, characterized in that, The torque loop control strategy employs a recursive least squares method to identify motor parameters online. By continuously acquiring real-time data pairs of current and torque, an optimization objective of minimizing the sum of squared errors is constructed; The torque coefficient estimate is dynamically updated using a recursive algorithm. When new data is received, the parameter estimate is corrected based on the prediction error and the gain coefficient. A high-precision current-torque mapping model is established using the accurate torque coefficient obtained from identification. Based on the torque synchronization control law, the consistency of the output torque of the two motors is ensured. According to the proportional relationship between the torque coefficients of the master and slave motors and the proportional-integral adjustment of the torque error, the current command of the second motor is dynamically generated.

7. The method for synchronous and coordinated control of dual motors in an electric helicopter according to claim 5, characterized in that, electromagnetic torque of the slave motor Tracking reference torque And the disturbance is estimated through feedforward compensation. Counteracting the effects of load disturbances and mechanical coupling: （11） in, Torque command, For reference torque, For load disturbance; （12） Where B is the damping coefficient; To estimate the load disturbance d, we treat the load disturbance d as an extended state z=d, and assume its derivative... With rotational speed As state variables, the system dynamics are: （13） The standard form is: （14） in: （15） Augmented state equation: （16） The extended state observer (ESO) estimates the state x and the perturbation z, with the estimates being respectively... and The dynamic equation of ESO is: （17） in, , , . Substitute parameters: （18） Define the estimation error: Disturbance error: ; （19） Substitute parameters: （20） Disturbance error dynamics: （21） The error system is as follows: （22） like =0, the characteristic polynomial is: （23） Select gain , Make the characteristic polynomial as: （24） The eigenvalue is s = -ω0 (a repeated root), which ensures the stability of the ESO and the convergence rate is adjusted by ω0. Define torque coefficient ,but: .

8. The method for synchronous coordinated control of dual motors in an electric helicopter according to claim 6, characterized in that, K is estimated online using the least squares method, and data pairs (iq(k), Te(k)) are collected. The objective is to minimize the sum of squared errors. （25） Estimated value: （26） flux linkage estimation: （27） Constructing Lyapunov functions: （28） Taking its derivative, we get: （29） Will , , , , Substitute (29): （30） make Eliminate overlapping terms: （31） because , , , >0, and >0, therefore 0. The system is globally asymptotically stable; To ensure consistent torque between the two motors, the auxiliary motor current command i q2 *: （32） The electromagnetic torque of the second motor satisfies: （33） Assuming the current loop response speed is much higher than the torque loop, we can approximate it as iq2=i q2 * Substituting (32) into (33) yields: （34） Therefore, we can conclude that: （35） The closed-loop characteristic equation of the system is: (36) This equation corresponds to a standard second-order system: (37) Among them: natural frequency , , is the damping ratio. Therefore, the parameter formula is derived as follows: , .

9. The method for synchronous and coordinated control of dual motors in an electric helicopter according to claim 1, characterized in that, The main control motor drive system communicates with the main control motor drive system in real time via CAN bus. Under normal working conditions, the main control motor is responsible for speed control, and the slave control motor performs torque following. When the master motor fails, the slave motor automatically and seamlessly switches from torque control mode to speed control mode, and suppresses overshoot oscillation during the mode switching process through an adaptive parameter adjustment strategy.

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