阅读说明：本技术 一种水下航行器多电机协调控制方法及控制系统 (Multi-motor coordination control method and control system for underwater vehicle ) 是由 杜昭平 顾祥 王伟然 李长江 于中奇 于 2021-07-09 设计创作，主要内容包括：本发明公开了一种水下航行器多电机协调控制方法,步骤如下：步骤1：速度反馈补偿控制器、电流反馈补偿控制器；步骤2：获取所有永磁同步电机的转速；步骤3：混合反馈补偿控制器中的速度反馈补偿控制器根据输入的转速信号输出同步转速信号；混合反馈补偿控制中的电流反馈补偿控制器根据输入的转速信号输出补偿电流信号；步骤4：对所有永磁同步电机进行转速调控,当所有永磁同步电机的转速与同步转速信号中的转速不相同时,返回步骤2；当所有永磁同步电机的转速与同步转速信号中的转速相同时,完成调控。本发明能够提高系统灵活性、鲁棒性,能够更好地对系统的动态性能进行调节,使系统迅速达到稳定。(The invention discloses a multi-motor coordination control method for an underwater vehicle, which comprises the following steps: step 1: a speed feedback compensation controller, a current feedback compensation controller; step 2: acquiring the rotating speed of all permanent magnet synchronous motors; and step 3: a speed feedback compensation controller in the hybrid feedback compensation controller outputs a synchronous rotating speed signal according to an input rotating speed signal; a current feedback compensation controller in the hybrid feedback compensation control outputs a compensation current signal according to an input rotating speed signal; and 4, step 4: regulating and controlling the rotating speed of all the permanent magnet synchronous motors, and returning to the step 2 when the rotating speed of all the permanent magnet synchronous motors is different from the rotating speed in the synchronous rotating speed signal; and when the rotating speeds of all the permanent magnet synchronous motors are the same as the rotating speeds in the synchronous rotating speed signals, the regulation and control are completed. The invention can improve the flexibility and robustness of the system, and can better adjust the dynamic performance of the system, so that the system is quickly stabilized.)

1. A multi-motor coordination control method for an underwater vehicle is characterized by comprising the following steps: when a rotating shaft of a certain permanent magnet synchronous motor suddenly changes, the number of permanent magnet synchronous motors is regulated and controlled, and the method comprises the following specific steps:

step 1: constructing a hybrid feedback compensation controller comprising: a speed feedback compensation controller, a current feedback compensation controller;

step 2: acquiring the rotating speeds of all permanent magnet synchronous motors, and taking the rotating speeds as input signals of a hybrid feedback compensation controller;

and step 3: a speed feedback compensation controller in the hybrid feedback compensation controller outputs a synchronous rotating speed signal according to an input rotating speed signal; a current feedback compensation controller in the hybrid feedback compensation control outputs a compensation current signal according to an input rotating speed signal;

and 4, step 4: regulating and controlling the rotating speed of all permanent magnet synchronous motors according to the synchronous rotating speed signal, the compensating current signal and the rated control current,

when the rotating speeds of all the permanent magnet synchronous motors are different from the rotating speed in the synchronous rotating speed signal, returning to the step 2;

and when the rotating speeds of all the permanent magnet synchronous motors are the same as the rotating speeds in the synchronous rotating speed signals, the regulation and control are completed.

2. The multi-motor coordinated control method for the underwater vehicle as claimed in claim 1, wherein the speed feedback compensation controller in the step 1 is: and the fuzzy PI controller is constructed by combining a fuzzy algorithm and a PID algorithm.

3. The multi-motor coordinated control method of the underwater vehicle as claimed in claim 1 or 2, wherein the current feedback compensation controller in the step 1 is: a coupling coefficient K.

4. The multi-motor coordinated control method for the underwater vehicle as claimed in claim 3, wherein the coupling coefficient K satisfies the following condition:

wherein p is the number of pole pairs; psi_fIs a linkage flux linkage; b is a friction coefficient; a. b is a constant.

5. The multi-motor coordinated control method of the underwater vehicle as claimed in claim 1, wherein the specific method for the speed feedback compensation controller to output the synchronous rotating speed signal according to the input rotating speed signal in the step 3 is as follows: the rotating speed signal is used as the input of a fuzzy PI controller, and is regulated by the fuzzy PI controller to output a synchronous rotating speed signal, wherein the input deviation e and the deviation change rate e of the fuzzy PI controller_cRespectively as follows:

wherein，n_iIs the i-th motor output speed, n_lIs to remove n_iThe output speed of the outer l-th motor, e (t), is the deviation of speed at time t, and e (t-1) is the deviation at time t-1.

6. The multi-motor coordinated control method of the underwater vehicle as claimed in claim 1 or 5, wherein the specific method for the current feedback compensation controller to output the compensation current signal according to the input rotation speed signal in the step 3 is as follows: and taking the product of the coupling coefficient K and the rotating speed current corresponding to the rotating speed signal as a compensation current signal.

7. An underwater vehicle multi-motor cooperative control system capable of operating the underwater vehicle multi-motor cooperative control method according to any one of claims 1 to 6, the underwater vehicle multi-motor cooperative control system comprising: the system comprises a virtual main shaft control module, a hybrid feedback compensator module, a frequency converter module, a rotating speed loop controller module, a current loop controller module and a permanent magnet synchronous motor;

the output end of the virtual main shaft control module is connected with the proportional control module; the output end of the proportional controller module is connected with the rotating speed loop controller module; the output end of the rotating speed loop controller module and the output end of the permanent magnet synchronous motor are connected with the current loop controller module; the output end of the current loop controller module is connected with the frequency converter module; the output end of the frequency converter module is connected with the permanent magnet synchronous motor module; the output end of the permanent magnet synchronous motor is connected with the hybrid feedback compensator module; the output end of the hybrid feedback compensation controller module is connected with the rotating speed loop controller module and the current loop controller module;

the virtual main shaft control module is used for receiving an output torque signal of the permanent magnet synchronous motor and outputting a rotating speed regulation feedback signal to the proportion control module through calculation;

the hybrid feedback compensator module is used for receiving the output rotating speed signal of the permanent magnet synchronous motor, adjusting the sudden change of the rotating speed of the driven shaft and compensating the rotating speed signal and the current signal through calculation;

the frequency converter module is used for controlling the permanent magnet synchronous motor module based on the signal generated by the current loop controller module;

the rotating speed loop controller module controls the current loop controller module based on rotating speed signals generated by the proportional controller module, the permanent magnet synchronous motor and the hybrid feedback compensator module;

the current loop controller module controls the frequency converter module based on current signals generated by the rotating speed loop controller module, the permanent magnet synchronous motor module and the hybrid feedback compensator module;

the permanent magnet synchronous motor outputs a rotating speed signal based on the signal generated by the frequency converter module and controls the rotating speed loop controller module, the current loop controller module, the hybrid feedback compensator module and the virtual spindle motor module based on the torque module.

8. The multi-motor coordinated control system of the underwater vehicle as recited in claim 7, further comprising: the input end of the proportional control module is connected with the output end of the virtual spindle control module, the output end of the proportional control module is connected with the input end of the rotating speed loop controller module, and the proportional control module controls the rotating speed loop controller module based on the rotating speed adjusting feedback signal of the virtual spindle motor module.

9. The system for the multi-motor coordinated control of the underwater vehicle as claimed in claim 7, wherein the rotation speed loop controller module is: fuzzy fractional order PI^λA controller; the fuzzy fractional order PI^λThe controller is composed of a fuzzy control method, a fractional order method and a PID control method and is used for regulating and controlling synchronous rotating speed signals and outputting current signals to the current loop controller module.

Technical Field

The invention relates to the technical field of control of underwater vehicles, in particular to a multi-motor coordination control method and a multi-motor coordination control system for an underwater vehicle.

Background

The small underwater vehicle mostly works in shallow water areas or water areas with narrow and complicated underwater spaces, and is greatly influenced by water flow and surge interference. The water conditions of shallow water areas and water areas with complex terrain are complex and variable, and the stable operation of the small underwater vehicle in the environment is a hotspot and difficulty of the current underwater vehicle research. The high-stability and high-disturbance-resistance underwater coordinated control is the basis for the small underwater vehicle to execute various tasks, the small underwater vehicle can realize quick response and accurate synchronization of motors under strong disturbance in the high-stability and high-disturbance-resistance control, and the realization of the multi-motor coordinated driving propeller motion control of the small underwater vehicle becomes a key problem which is vital and urgent to solve.

For an underwater complex nonlinear environment, when a nonlinear system with numerous disturbance factors is faced, when a single motor is continuously used for controlling an underwater vehicle, the force is unconscious, the control precision and the control effect cannot be guaranteed, and the degree which the underwater vehicle wants to achieve is achieved, so that the realization of the underwater coordinated control of multiple motors is a research with great significance. For underwater vehicles, the smaller volume can accomplish more tasks that are difficult to accomplish by large underwater robots. Therefore, the permanent magnet synchronous motor with the advantage of volume controllability can be applied to multi-motor control as our preferred application. The permanent magnet synchronous motor has the advantages of simple structure principle, easy maintenance, low manufacturing cost and the like, and along with the gradual maturity of modern motor control technologies, including vector control and direct torque control technologies, the current alternating current speed regulating system can be comparable to a direct current speed regulating system. However, for a control system in which two or more motors are simultaneously driven, especially when the motors in the system are combined with specific loads, the general control targets change accordingly, and a multi-input multi-output nonlinear complex system with strong coupling and high-order time variation is essentially formed, so that for a multi-motor synchronous control system, the research on a synchronous control structure strategy and a synchronous control algorithm is provided, and the research on the multi-motor synchronous coordinated control system also becomes a research hotspot.

In a multi-shaft synchronous control system, due to the inherent characteristics of a virtual spindle control structure, the synchronous performance of the virtual spindle control system in a stable state is poor, when a motor shaft is disturbed by disturbance quantities, obvious synchronous errors can occur between shafts, the coupling relation between the shafts is lacked, and information feedback is not provided for each other, so that a constant static difference can be kept between a main reference value and each shaft and is difficult to eliminate when the system is in a start-stop stage and/or the driven shafts are disturbed by unbalanced load disturbance quantities, the asynchronous phenomenon can occur between the driven shafts, the synchronous relation can be disturbed, and even the system is completely out of step.

Disclosure of Invention

The invention provides a multi-motor coordination control method and a multi-motor coordination control system for an underwater vehicle, which are used for solving the problems of load torque increase and motor rotating speed dip in virtual spindle control in the prior art and the technical problem that the proportional control of the rotating speed of a shaft cannot be carried out.

The invention provides a multi-motor coordination control method for an underwater vehicle, which comprises the following steps: when a rotating shaft of a certain permanent magnet synchronous motor suddenly changes, the number of permanent magnet synchronous motors is regulated and controlled, and the method comprises the following specific steps:

step 1: constructing a hybrid feedback compensation controller comprising: a speed feedback compensation controller, a current feedback compensation controller;

step 2: acquiring the rotating speeds of all permanent magnet synchronous motors, and taking the rotating speeds as input signals of a hybrid feedback compensation controller;

and step 3: a speed feedback compensation controller in the hybrid feedback compensation controller outputs a synchronous rotating speed signal according to an input rotating speed signal; a current feedback compensation controller in the hybrid feedback compensation control outputs a compensation current signal according to an input rotating speed signal;

and 4, step 4: regulating and controlling the rotating speed of all permanent magnet synchronous motors according to the synchronous rotating speed signal, the compensating current signal and the rated control current,

when the rotating speeds of all the permanent magnet synchronous motors are different from the rotating speed in the synchronous rotating speed signal, returning to the step 2;

and when the rotating speeds of all the permanent magnet synchronous motors are the same as the rotating speeds in the synchronous rotating speed signals, the regulation and control are completed.

Further, the speed feedback compensation controller in step 1 is: and the fuzzy PI controller is constructed by combining a fuzzy algorithm and a PID algorithm.

Further, the current feedback compensation controller in step 1 is: a coupling coefficient K.

Further, the coupling coefficient K satisfies:

wherein p is the number of pole pairs; psi_fIs a linkage flux linkage; b is a friction coefficient; a. b is a constant.

Further, the specific method for the speed feedback compensation controller to output the synchronous rotational speed signal according to the input rotational speed signal in step 3 is as follows: the rotating speed signal is used as the input of a fuzzy PI controller, and is regulated by the fuzzy PI controller to output a synchronous rotating speed signal, wherein the input deviation e and the deviation change rate e of the fuzzy PI controller_cRespectively as follows:

wherein n is_iIs the i-th motor output speed, n_lIs to remove n_iThe output speed of the first motor, e (t), is the speed deviation at the moment t, e (t-1) is the deviation at the moment t-1;

further, the specific method for the current feedback compensation controller to output the compensation current signal according to the input rotation speed signal in step 3 is as follows: and taking the product of the coupling coefficient K and the rotating speed current corresponding to the rotating speed signal as a compensation current signal.

The invention also provides a multi-motor coordination control system of the underwater vehicle, which can operate the multi-motor coordination control method of the underwater vehicle, and comprises the following steps: the system comprises a virtual main shaft control module, a hybrid feedback compensator module, a frequency converter module, a rotating speed loop controller module, a current loop controller module and a permanent magnet synchronous motor;

the output end of the virtual main shaft control module is connected with the proportional control module; the output end of the proportional controller module is connected with the rotating speed loop controller module; the output end of the rotating speed loop controller module and the output end of the permanent magnet synchronous motor are connected with the current loop controller module; the output end of the current loop controller module is connected with the frequency converter module; the output end of the frequency converter module is connected with the permanent magnet synchronous motor module; the output end of the permanent magnet synchronous motor is connected with the hybrid feedback compensator module; the output end of the hybrid feedback compensation controller module is connected with the rotating speed loop controller module and the current loop controller module;

the virtual main shaft control module is used for receiving an output torque signal of the permanent magnet synchronous motor and outputting a rotating speed regulation feedback signal to the proportion control module through calculation;

the hybrid feedback compensator module is used for receiving the output rotating speed signal of the permanent magnet synchronous motor, adjusting the sudden change of the rotating speed of the driven shaft and compensating the rotating speed signal and the current signal through calculation;

the frequency converter module is used for controlling the permanent magnet synchronous motor module based on the signal generated by the current loop controller module;

the rotating speed loop controller module controls the current loop controller module based on rotating speed signals generated by the proportional controller module, the permanent magnet synchronous motor and the hybrid feedback compensator module;

the current loop controller module controls the frequency converter module based on current signals generated by the rotating speed loop controller module, the permanent magnet synchronous motor module and the hybrid feedback compensator module;

the permanent magnet synchronous motor outputs a rotating speed signal and a torque module based on the signal generated by the frequency converter module to control the rotating speed loop controller module, the current loop controller module, the hybrid feedback compensator module and the virtual spindle motor module;

further, the multi-motor coordination control system for the underwater vehicle further comprises: the input end of the proportional control module is connected with the output end of the virtual spindle control module, the output end of the proportional control module is connected with the input end of the rotating speed loop controller module, and the proportional control module controls the rotating speed loop controller module based on the rotating speed adjusting feedback signal of the virtual spindle motor module.

Further, the rotating speed ring controller module is: fuzzy fractional order PI^λA controller; the fuzzy fractional order PI^λThe controller is composed of a fuzzy control method, a fractional order method and a PID control method and is used for regulating and controlling synchronous rotating speed signals and outputting current signals to the current loop controller module.

The invention has the beneficial effects that:

1. the invention provides a fuzzy fractional order PI in a speed ring under a single motor vector model on an axis^λThe controller is added with a variable adjustable parameter lambda, the order of the controller can be selected at will, the flexibility and the robustness of the system can be improved, a great positive effect can be achieved on the aspects of overall control performance and the like, the dynamic performance of the system can be better adjusted, and the system can achieve a better control effect.

2. Aiming at the problem of synchronization error caused by insufficient coupling of the traditional structure of the virtual main shaft, the feedback compensation controller designed by the invention can well coordinate the states of all the slave shafts, greatly eliminates the influence of the synchronization error on a multi-motor running system, and has the advantages of stable system, fast dynamic response and higher synchronization precision after a synchronization speed regulator is added.

3. Aiming at the problem that a synchronous control algorithm based on virtual spindle control cannot meet the requirement of proportional synchronous control in a target system, the embodiment designs a multi-motor proportional synchronous control method based on a virtual spindle structure.

Drawings

The features and advantages of the present invention will be more clearly understood by reference to the accompanying drawings, which are illustrative and not to be construed as limiting the invention in any way, and in which:

FIG. 1 is a block diagram of a speed and current feedback compensator in an embodiment of the present invention;

FIG. 2 is a block diagram of a fuzzy PI controller according to an embodiment of the present invention;

FIG. 3 is a block diagram of a speed compensator for the motor 1 in an embodiment of the present invention;

fig. 4 is a structural diagram of a current feedback compensator of the motor 1 in the embodiment of the present invention;

FIG. 5 is a block diagram of a virtual spindle tri-axial synchronization control with hybrid feedback compensation in an embodiment of the present invention;

FIG. 6 is a fuzzy fractional order based PI in an embodiment of the present invention^λThe whole structure diagram of a PMSM control system of the speed controller;

FIG. 7 is a fuzzy fractional order PI of an embodiment of the present invention^λA control block diagram;

FIG. 8 is a flow chart of the design of a fuzzy controller in an embodiment of the present invention;

FIG. 9 is a diagram of a three-motor proportional synchronous control system based on a virtual spindle according to an embodiment of the present invention;

fig. 10 is a flow chart of the operation of the system in an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The specific embodiment of the invention provides a multi-motor coordination control method for an underwater vehicle, which comprises the following steps:

when a rotating shaft of a certain permanent magnet synchronous motor suddenly changes, the number of permanent magnet synchronous motors is regulated and controlled, and the method comprises the following specific steps:

step 1: constructing a hybrid feedback compensation controller comprising: a speed feedback compensation controller and a current feedback compensation controller. The speed feedback compensation and the current feedback compensation are two feedback compensation modes aiming at the asynchronous rotation speed, one mode is to carry out direct feedback control on a rotation speed loop, the other mode is to feed back a compensation quantity to a current loop after a rotation speed difference value (synchronous error) passes through a gain of a coupling coefficient K, and the two feedback compensation signals supplement each other after load disturbance by combining the rapidity of the reaction of the current loop, so that the phenomenon of asynchronous rotation speed in a system is inhibited, and the dynamic property and the synchronism of multiple motors are improved. Taking a certain motor shaft as an example, a hybrid feedback controller based on feedback compensation of rotating speed and current is constructed as shown in figure 1.

In FIG. 1, n₁、n₂、n₃Input speed signal for speed feedback compensation controller and current feedback compensation, Δ n is output terminal, i_qr1Is the compensation current signal output by the current feedback compensator, and K is the coupling coefficient.

Step 2: obtaining the rotating speed n of all permanent magnet synchronous motors₁、n₂、n₃The rotating speed is used as an input signal of the hybrid feedback compensation controller;

and step 3: firstly, a speed feedback compensation controller in a hybrid feedback compensation controller is designed, and the traditional PID control and fuzzy control are selected to design the speed feedback compensation. When feedback compensation is designed, the influence of sudden change load and sudden change rotating speed on a system is mainly considered, and the change is controlled by using the combined action of a proportional control link and an integral control link of PID control. Because the signal overshoot of the system operation is not obvious, the function of the differential part is not considered, and the PI regulator is adopted, so that the PI parameter is more convenient to set, and the control performance of feedback compensation is not reduced.

According to the characteristics of the fuzzy algorithm, inputting the deviation e and deviation of the given rotating speed signal and the feedback signalRate of change e of_cAnd then outputs the delta K of PI control under the action of a fuzzy controller_P，ΔK_ITwo parameters, Δ K_PAnd Δ K_ICan be according to e and e_cThe value of (a) is modified in real time. The structure of the fuzzy PI adaptive controller is designed as shown in figure 2.

In FIG. 2, the deviation e and the deviation change rate e_cRespectively as follows:

in the formula (1), n_iIs the i-th motor output speed, n_lIs to remove n_iThe output speed of the outer l-th motor, e (t), is the deviation of speed at time t, and e (t-1) is the deviation at time t-1.

For the speed feedback compensator to be implemented, { NB, NM, NS, ZO, PS, PM, PB } is set as a fuzzy subset of the controller and is applicable to the input and output quantities of the control. Setting a rotation speed error e and an error rate e according to the control requirement_cHas a discourse range of [ -3,3 [)]Output Δ K_PHas a discourse field of [ -1,1]，K_iHas a discourse field of [ -1.5,1.5 [)]. Set the ambiguity field to [ -0.5,0.5 [)]. Discretizing the fuzzy domain into { -0.5, -0.25, -0.125,0,0.125,0.25,0.5} according to the control requirement.

Solving formula K according to the scale factor and the quantization factor₁＝n₁/x₁、K₂＝x₂/n₂Determining the input variable deviation e and the rate of change e_cQuantization factor K of₁1/6, input variable Δ K_PScale factor K of_p2＝2，ΔK_IScale factor K of_I23. To reduce the complexity of the calculation, a trigonometric function is selected as the membership function of this embodiment.

According to error e and error change rate e_cAnd on-line adjusting the proportionality coefficient K by combining different values of the coefficient in the PI control_pIntegral coefficient K_iAnd an integration order λ. When adjusting a fuzzy PI controller in a control system, it should be directed to K_pAnd K_iBetweenThe relationship (c) and the influence on the system are fully considered. Thus obtaining Δ K_pAnd Δ K_iThe fuzzy rule control table of (1):

TABLE 1

The method of defuzzification by using the gravity center method is adopted to obtain the output delta K of the fuzzy controller after the correction_pAnd Δ K_i. Thus, by combining the fuzzy control, the fuzzy PID control formula can be obtained according to the rule of the traditional PID control system as follows:

y^*＝K'_Pe(t)+K'_Ie(t) (2)

of formula (II) K'_P＝K_P+ΔK_P，K′_I＝K_I+ΔK_IThe parameter values are the fuzzy PI adjusted parameter values respectively.

According to the basic idea of the speed feedback compensator, a three-motor control structure is taken as a basis, and a specific speed feedback compensation structure is designed as shown in fig. 3, taking a certain motor as an example.

In FIG. 3, n₁、n₂、n₃Δ n is an output terminal, which is an input terminal of the velocity compensator. Control principle of speed regulator: n is₁To the actual output speed from the shaft 1, n₂、n₃The actual output speed from the shaft 2 and the shaft 3. n is₁And n₂Synchronization error e of₁And n₁And n₃Synchronization error e of₂Respectively obtaining output control quantity n after fuzzy PI regulation of the compensator_s1、n_s2Taking n_s1And n_s2Is used as a total output control amount deltan, i.e., a speed compensation input amount for keeping the slave axis 1 synchronized with the slave axes 2 and 3. The other two slave axis velocity compensators are similar.

Then, a current feedback compensation controller in the hybrid feedback compensation controller is designed, and the current feedback compensator is designed and analyzed below.

When the motor is runningWhen relatively stable disturbance is applied, the sudden load disturbance amount will cause the rotation speed between the slave shafts to be asynchronous, and affect the synchronization effect of the system, and for example, one of the motors is taken as an example, and the structural diagram of the current feedback compensator is designed as shown in fig. 4. In the figure,. DELTA.T_r1Is the amount of disturbance of the load acting on the motor. Taking three-motor control as an example, in the current feedback compensator, when the output rotating speeds of the current motor and the other two motors are different (the rotating speeds are asynchronous), the output rotating speeds of the current motor and the other two motors are compared with each other to obtain a difference value of the fed-back rotating speeds, and the difference value signal is subjected to the gain action of a coupling coefficient K to obtain a current feedback signal, so that the current feedback signal is fed back to a current loop of the current motor shaft to perform feedback control. Therefore, each shaft can acquire the dynamic information of other shaft motors, and the coupling between the motor shafts is enhanced, so that a better synchronization effect is obtained in the operation of multiple motors. Because in the motor system, the electromagnetic time constant in the motor is smaller than the mechanical time constant of the rotating speed, the response of the current loop in the shaft motor to the dynamic state is far better than that of the rotating speed loop in the motor, and therefore after the load disturbance, the asynchronous slip signal after the feedback gain is fed back to the current loop of the motor to be adjusted, and the effect is better than that of the slip signal fed back to the rotating speed loop, and the dynamic property and the synchronism of the system can be better improved.

(1) When the three motors run normally and have no disturbance, delta T_r1＝ΔT_r2＝0，n₁＝n₂＝n₃＝n_r，i_qf1＝i_qf2＝i_qf3And when the three-motor rotation speed difference is 0, the current feedback compensator does not work.

(2) Taking one of the motors as an example, when the system runs stably, the rotating speed signal keeps n₁＝n₂＝n₃＝n_r. When t is equal to t₀Load disturbance Δ T_r1Start to disturb the motor, then at t₀Is momentarily provided with T_e1-(T_r1+ΔT_r1)＜T_e2-T_r2Thus resulting in n₁＜n₂. At t ═ t₁(t₁＞t₀) Time, synchronization error Δ n (Δ) between three motorsn＝|n₁-n_pI) reaches the maximum, at the moment, a coupling coefficient K is set, so that a corresponding current compensation signal i is generated after delta n passes through the gain effect of the coefficient_qf1Feeding back the speed signal n to the current loop of the motor, and outputting the speed signal n to the motor shaft under the action of the current loop₁The set value is continuously approached, and at the same time, the other two motors are also corresponding to the signal n by a corresponding regulating mechanism₁The synchronous approach to the given value can gradually reduce the difference of the rotating speeds of the three motors in the adjusting process, thereby realizing the synchronous recovery performance of the multiple motors under disturbance.

The coupling coefficient K determines to some extent the control effect of the current feedback compensation. The too small value of K can influence the synchronous control effect, and too large value can make the compensator adjust too fast, makes the rotational speed produce the oscillation, so this embodiment has confirmed the theoretical scope of K value that can make the system keep better synchronization performance through deriving.

In FIG. 4, assume that n_p＝an₁，T_r1+ΔT_r1＝bT_e1When the motor is disturbed by the load, the input i can be obtained_qr1(s) to output n₁(s) a transfer function of

In the formula, p is a polar pair number; psi_fIs a linkage flux linkage; j is moment of inertia; b is the friction coefficient.

If the control link is required to be kept relatively stable, the characteristic roots of the corresponding transfer functions all fall in the left half plane of the s-plane, so that the characteristic roots can be obtained

In the formula, K is a coupling coefficient; p is the number of pole pairs; psi_fIs a linkage flux linkage; b is the friction coefficient.

According to the formula (4), the internal parameters of the motor, the load disturbance of the motor and the like can affect the K value, and based on the consideration of engineering practice application, the synchronous performance of the system can be gradually improved along with the increase of K on the basis of an actual motor prototype. Especially when K is more than 25, the synchronous error of the motor system is obviously reduced, but when K is larger and larger, the slip can be continuously reduced, but the slip can generate a large-fluctuation current feedback compensation value after passing through larger K, so that the rotating speeds of a plurality of motors are continuously oscillated and cannot be stabilized at a given value.

And 4, step 4: according to two feedback compensation modes aiming at the asynchronous rotation speed designed in the steps 1-3, one mode is to carry out direct feedback control on a rotation speed loop, the other mode is to feed back a compensation quantity serving as a compensation quantity to a current loop after a rotation speed difference value (synchronous error) passes through a gain of a coupling coefficient K, and the two feedback compensation signals supplement each other after load disturbance by combining the rapidity of the reaction of the current loop, so that the phenomenon of asynchronous rotation speed in a system is inhibited, and the dynamic property and the synchronism of multiple motors are improved. The rotating speed and current hybrid feedback compensator is arranged in a virtual spindle control system of a three-motor, and a virtual spindle three-axis synchronous control structure diagram with hybrid feedback compensation is built as shown in fig. 5.

In fig. 5, a hybrid compensation feedback network of rotational speed and current is established between the slave axes in the virtual master axis control configuration. The simulation model mainly comprises a fuzzy fractional order PI^λThe device comprises a speed ring adjusting module, a current ring module, a permanent magnet synchronous motor vector control module, a speed compensation module and the like.

When the rotating speeds of all the permanent magnet synchronous motors are different from the rotating speed in the synchronous rotating speed signal, returning to the step 2;

and when the rotating speeds of all the permanent magnet synchronous motors are the same as the rotating speeds in the synchronous rotating speed signals, the regulation and control are completed.

Synchronous rotating speed signals are input into a rotating speed ring controller module, and the rotating speed ring controller module is as follows: fuzzy fractional order PI^λA controller; the fuzzy fractional order PI^λThe controller is composed of a fuzzy control method, a fractional order method and a PID control method and is used for regulating and controlling the synchronous rotating speed signal and outputting a mixed current signal to powerA flow loop controller module.

As shown in FIG. 6, fuzzy fractional order PI is to be established^λThe single motor vector control system is formed by adding a single motor vector control model into an improved speed ring PI controller, the improved speed ring PI controller is the combination of a fuzzy control theory and a fractional order PI controller, and compared with an integer order PI controller in a traditional vector control model, the improved speed ring PI controller introduces a parameter lambda, so that the system has stronger control flexibility and robustness, meanwhile, the complexity of the system is increased, and the difficulty of parameter setting is increased. Single-motor vector model speed ring division fuzzy fractional order PI^λThe current loop remains unchanged except for replacing the traditional integer order PI controller by the controller. Improved speed loop PI controller, i.e. fuzzy fractional order PI^λThe controller is composed of a fuzzy controller and a fractional order PI^λD^μController composition, fuzzy fractional order PI^λThe control block diagram is shown in fig. 7.

The fractional calculus cited here is not long enough to be used in industrial control, and the calculus operator of the fractional calculus is fractional, or of any order^[67]. The expression is as follows:

in the formula (I), the compound is shown in the specification,and a and t respectively represent upper and lower limits of a calculus solving time variable, and alpha is an order. And the order of alpha is fractional, R (alpha) denotes alpha is a real number,

with the further research of the fractional order theory, the fractional order expression has many ways, mainly including Grunwald-Letnikov (GL) definition, Riemann-Liouville (RL) definition and Caputo definition, and for the subject, the Caputo solution is used because the result of the Caputo solution is bounded.

The Caputo fractional calculus is defined as:

in the formula: and alpha is m + gamma, m is an integer, and gamma is more than 0 and less than or equal to 1.

The Caputo fractional order integral is defined as:

the Caputo fractional calculus is collectively defined as:

in the formula: m-1 is more than or equal to m, and m belongs to N.

The fractional order differential equation solving method is as follows:

the initialization condition of equation (9) is:

laplace transformation is performed on equation (10):

the solution of the Laplace inverse transformation fractional order differential equation to equation (11) is:

wherein 1/Γ (-m) — 0, m ≧ 0, and m ∈ N.

Fractional orderPI^λD^μThe transfer function expression of (a) is:

in the formula, lambda is more than 0, mu is less than 2, K_pIs the proportionality coefficient, K_iIs the integral coefficient, K_dIs a differential coefficient, and λ and μ are fractional order factors of the integral term and the differential term, respectively.

Generally, the effect of lambda on the control system is that as lambda increases, the system reaction speed is faster before slower, and the smaller lambda, the smaller the overshoot. The reaction rate is also increased and then decreased as μ increases, and the smaller μ, the smaller the overshoot.

According to the PID theory, K_DAnd the zero is set, the influence of an integral link is avoided, so that the torque output regulation range of the controller is larger, the robustness is better and the overshoot is greatly reduced due to the addition of the integral order lambda. But fractional order PI^λThe method can only change the order of the variable in the integral term, cannot change the proportion and the integral coefficient in the PI, and has limitation. If the fuzzy control theory is added on the basis of the fractional order PID theory, the coefficient and the variable in the PID can be simultaneously controlled, so that the system is more flexible.

Fuzzy control rules can be set according to the experience of PID adjustment to establish fuzzy self-adaptive fractional order PI^λProvided is a system.

Improved speed loop fuzzy fractional order PI^λIn the controller, the fuzzy controller needs to control the system optimization process according to the system deviation and the deviation change rate. The design steps of the fuzzy controller comprise fuzzification, fuzzy reasoning solution and the like of input and output variables. The design process of the fuzzy controller is shown in figure 8.

Firstly, input and output physical quantities are determined, as shown in fig. 7, the output rotating speed is fed back to an input end to be differenced to obtain a rotating speed deviation e (t), the rotating speed deviation e (t) is derived to obtain a rotating speed deviation change rate ec (de) (t)/dt, and a PI is constructed according to the calculated rotating speed deviation e and the rotating speed deviation change rate ec^λController parameter Δ k_pΔ k, Δ λ and the binary functional relationship of e and ec:

Δk_p＝f_p(e,ec)

Δk_i＝f_i(e,ec)

Δλ＝f_λ(e,ec) (14)

designing a fuzzy fractional order PI according to the theory of a fuzzy controller and the practical working condition related to the embodiment^λThe controller comprises the following design steps:

(1) determining fuzzy sets and domains of discourse

The present embodiment sets { NB, NM, NS, ZO, PS, PM, PB } as a fuzzy subset of the controller, and is applicable to the input and output quantities of the control. Selecting speed errors e and e according to the rotating speed of the motor_cIn the range of [ -3,3]. Will output Δ K according to the model parameters of chapter II_pIs set to [ -1,1 [ ]]，ΔK_iHas a discourse field of [ -1.5,1.5 [)]The discourse domain of Δ λ is set to [0,1 ]]. Set their ambiguity domains to [ -0.5,0.5 [)]. Discretizing the fuzzy domain into { -0.5, -0.25, -0.125,0,0.125,0.25,0.5} according to the control requirement.

(2) Variable fuzzification and selection of membership function

Fuzzification operation is carried out on input quantities of the controller, namely the deviation value and the deviation change rate, and the fuzzy variable of the controller is ensured to be within the fuzzy domain range. The corresponding quantization factor solving formula is:

K₁＝n₁/x₁ (15)

the scaling factor is solved by

K₂＝x₂/n₂ (16)

In the formulae (15) and (16), K₁To quantize the factor, K₂Is a scale factor, x₁For the discourse of input quantities, n₁Is the fuzzy domain of the input quantity, x₂For the universe of output, n₂Is the domain of ambiguity of the output quantity.

The quantities shown in the following table can be obtained from the above expressions.

TABLE 2

To reduce computational complexity, variables e and e are input_cThe membership function of (2) selects a Gaussian function and outputs a variable delta K_p、ΔK_iAnd delta lambda, selecting a trigonometric function.

(3) Fuzzy rule

According to error e and error change rate e_cAnd on-line adjusting the proportionality coefficient K by combining different values of the coefficient in the PI control_pIntegral coefficient K_iAnd an integration order λ. PI (proportional integral)^λTwo parameters of the controller have the following effects in the system:

1. gain K along with proportional loop_pThe response speed of the whole system is increased, and the static error of the system is reduced, but when K is reached_pWhen the size is too large, the system can be obviously overshot, so that the stability of the system is influenced.

2. Integral term K_iThe steady-state error of the system can be effectively suppressed, but the stability of the system can be influenced, such as the problem of system overshoot.

3. Generally, the effect of lambda on the control system is that as lambda increases, the system reaction speed is faster before slower, and the smaller lambda, the smaller the overshoot.

The comprehensive three functions are to adjust the fuzzy PI controller in the control system according to K_pAnd K_iThe relationship between them and the influence on the system are fully considered. Thus obtaining Δ K_p、ΔK_iAnd λ are shown in tables 3, 4 and 5.

TABLE 3

TABLE 4

TABLE 5

(4) Defuzzification

The method of defuzzification by using the gravity center method is adopted to obtain the output delta K of the fuzzy controller after the correction_pAnd Δ K_iAccording to Δ K_pAnd Δ K_iThe parameters are adjusted online, and the following formula is provided:

K_p＝K_p0+ΔK_p (17)

K_i＝K_i0+ΔK_i (18)

λ＝λ₀+Δλ (19)

in formulae (17) to (19), K_p0、K_i0、λ₀Is K_p、K_iLambda, adjusted by a value delta K_p、ΔK_iAnd Δ λ to obtain the final proportionality coefficient K_pIntegral coefficient K_iAnd an integration order λ.

In order to obtain a relatively accurate and reasonable fuzzy output, the defuzzification process of the embodiment adopts a weighted average method in combination with specific working conditions.

Since the individual propellers will be given different control requirements when designing an underwater vehicle, and the synchronization requirements for speed will be different, the system will be designed to operate in certain proportions under certain conditions. Aiming at the problem that the existing synchronous control algorithm based on the virtual axis principle is difficult to meet the proportional synchronous control requirement in some target forming systems, a multi-motor proportional synchronous control method based on a virtual main shaft structure is designed.

The foregoing teaches the use of a fuzzy fractional order PI for the speed loop controller module^λControl is performed to fuzzy fractional order PI^λThe module is packaged into a slave axis model and a virtual main axis system which are embedded into a single motor to describe, and then the fuzzy fractional order PI^λThe structure of the improved virtual main shaft synchronous control system combined with the controller is shown as the structure of the control system in figure 9.

In a conventional mechanical synchronization scheme, each moving shaft is connected to a main shaft through a transmission mechanism, and the main shaft transmits a driving torque to each moving shaft and functions as a synchronization coordinator. When a certain motion shaft is disturbed to change the rotating speed, the change can influence the output of the main shaft through torque feedback, so that the speeds of other shafts change in the same trend, and the effect of reducing the synchronous error is achieved. The virtual main shaft control system establishes an electronic virtual shaft similar to a mechanical main shaft, the transmission characteristic of the electronic virtual shaft is similar to that of the mechanical main shaft, the principle is that a motor driving shaft is utilized to drive the virtual main shaft to simulate the mechanical main shaft characteristic, the load force on the shaft is fed back to the virtual main shaft, and the main shaft is analyzed and calculated to coordinate the moment balance between the main shaft and the driven shaft. The virtual main shaft has the characteristics of the traditional mechanical main shaft, namely the speed fluctuation of the driven shaft can quickly change the rotating speed of the virtual main shaft, and the normal speed compensation among the shafts is realized.

In this embodiment, the main shaft in the virtual main shaft is connected to each slave shaft, i.e. the motor servo system, and performs feedback control through the virtual main shaft to output torque to each slave shaft motor, where the relationship between the virtual main shaft output torque and the main shaft output rotation angle is as follows:

in the formula: t is the input drive torque of the spindle, T_iFor the driving torque of each slave shaft, i.e. the feedback torque fed back to the virtual main shaft, J_m、ω_mIs the moment of inertia and output angular velocity of the virtual spindle.

As known from hooke's law, for a synchronous system comprising n axes of motion, the drive torque provided by a virtual spindle is defined as:

T＝k_m(ω_r-ω_m) (21)

in the formula, k_mThe elastic coefficient of the virtual main shaft input end; omega_rFor theoretical setting of the speed of rotation, omega_mIs the actual rotational speed.

If the principal axis damping coefficient b is considered_mThen the virtual spindle calculation formula can be written as:

T₁＝b_m(ω_r-ω_m)+k_m∫(ω_r-ω_m)dt (22)

the magnitude of parameters such as elasticity and damping is related to the feedback torque of the slave shaft, and the formula of the feedback torque of each slave shaft is as follows:

T_i＝k_r(θ_i-θ_m)+k_ir∫(θ_i-θ_m)dt+b_r(ω_i-ω_m) (23)

in the formula, ω_iAnd ω_mThe rotating speed of each driven shaft and the actual rotating speed; theta_iRotationally displacing each of the shafts; theta_mIs the actual rotational angular displacement; k is a radical of_rAnd k_irRespectively, a stiffness gain and an integral stiffness gain; b_rIs the damping gain.

As shown in fig. 9, the virtual spindle control module may be described as the pmsm outputting a torque signal to an adder calculation module, and the adder calculation module outputting a sum of the torque signal and a rotational speed signal to the proportional control module after calculation by the proportional module and the differential module. Meanwhile, the rotating speed signal is fed back and input to the PI control module, and the sum of the output torque signal and the torque signal is subjected to difference output to the proportion module through the adjustment of the PI control module.

In the proportional control module, the rotation speed relationship among n motion axes in the synchronous system is assumed as follows: omega₁:ω₂:…:ω_k:…:ω_n＝μ₁:μ₂:…:μ_k:…:μ_n. Define the kth motion axis (largest scale factor, μ) with the worst control performance_k＝max(μ₁,μ₂,…μ_n) ) is equal to the virtual spindle output speed, the speed relationship between the moving axes is converted into:

therefore, the feedback moment relation of the motion axis of the improved virtual total axis structure should satisfy:

in the figure, as shown in formulas 20-23, the virtual control spindle receives the output torque of each shaft motor, obtains the feedback rotating speed through calculation and adjustment of the PI controller and transmits the feedback rotating speed to the proportional control module, and the system operation flow is shown in figure 10.

Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.