Control method of permanent magnet synchronous motor

Abstract

The invention provides a control method of a permanent magnet synchronous motor. A fractional order sliding mode controller is constructed by designing a fractional order sliding mode surface and a fractional order reaching law in a rotating speed outer ring; setting the parameters of the fractional order sliding mode controller by using a dung beetle algorithm to obtain the optimal control parameters of the fractional order sliding mode controller, and generating an optimal q-axis current control instruction by the fractional order sliding mode controller based on the optimal control parameters; a fractional order model prediction current controller is constructed by designing a fractional order prediction model and a fractional order cost function in the current inner loop, and is used for generating an optimal stator voltage control instruction; based on the optimal q-axis current control instruction and the optimal stator voltage control instruction, the rotating speed and the current of the target permanent magnet synchronous motor are controlled, so that the actual rotating speed and the current of the target permanent magnet synchronous motor are tracked to the given rotating speed and the given current; the control precision of the rotating speed of the permanent magnet synchronous motor is improved by suppressing the rotating speed fluctuation of the permanent magnet synchronous motor.

Description

Technical Field

[0001] The present invention relates to the technical field of synchronous motor control, and in particular to a control method for a permanent magnet synchronous motor. Background Art

[0002] Improving system reliability, improving power factor and reducing costs in the field of household appliances such as refrigerators, air conditioners and fans is a gradual development trend. Permanent magnet synchronous motors are often used in household appliances due to their high power density, large torque, small size, high efficiency, simple control and high precision. However, due to the different forms of loads driven by permanent magnet synchronous motors, the forms of load signals are also different. When these loads are added to the permanent magnet synchronous motor control system, the speed will fluctuate, which will cause vibration of the motor control system and affect the high-precision control of the permanent magnet synchronous motor speed. Summary of the invention

[0003] The present invention provides a control method for a permanent magnet synchronous motor, the purpose of which is to suppress rotation speed fluctuations to improve the control accuracy of the rotation speed of the permanent magnet synchronous motor.

[0004] In order to achieve the above object, the present invention provides a control method of a permanent magnet synchronous motor, comprising: Step 1, selecting a target permanent magnet synchronous motor, wherein the dual closed-loop control system of the target permanent magnet synchronous motor includes a speed outer loop and a current inner loop; Step 2, designing a fractional-order sliding surface and a fractional-order reaching law in the speed outer loop, and constructing a fractional-order sliding mode controller based on the fractional-order sliding surface and the fractional-order reaching law; Step 3, using the dung beetle algorithm to tune the parameters of the fractional-order sliding mode controller to obtain the optimal control parameters of the fractional-order sliding mode controller, and the fractional-order sliding mode controller generates the optimal q-axis current control command of the target permanent magnet synchronous motor based on the optimal control parameters; Step 4, designing a fractional-order prediction model and a fractional-order cost function in the current inner loop, and constructing a fractional-order model prediction current controller based on the fractional-order prediction model and the fractional-order cost function, wherein the fractional-order model prediction current controller is used to generate an optimal stator voltage control instruction for the target permanent magnet synchronous motor; Step 5: Control the speed and current of the target permanent magnet synchronous motor based on the optimal q-axis current control instruction and the optimal stator voltage control instruction, respectively, so that the actual speed and current of the target permanent magnet synchronous motor track the given speed and current.

[0005] Furthermore, the fractional-order sliding surface and fractional-order reaching law are designed in the speed outer loop, including: For a given target signal, define the position tracking error and velocity tracking error; Based on the position tracking error and the speed tracking error, a fast terminal sliding surface that converges within a preset time is constructed in the speed outer loop; Constrain the parameters in the fast terminal sliding surface and introduce fractional order differential linear terms to make the fast terminal sliding surface converge and obtain the fractional order sliding surface. The design introduces the reaching law of fractional order operator and obtains the fractional order reaching law which is used to make the double closed-loop control system enter the sliding mode state.

[0006] Furthermore, the expression of the fractional-order sliding surface is: in, represents the fractional sliding surface, represents the position tracking error, represents the speed tracking error, represents the fractional integral operator, represents the differential order, , represent positive real numbers, , All represent the parameters of the fast terminal sliding surface. .

[0007] Furthermore, the expression of the fractional-order reaching law is: in, represents the fractional-order reaching law, , and All represent undetermined coefficients, represents the fractional-order switching term.

[0008] Furthermore, the expression of the fractional-order sliding mode controller is: in, represents the fractional-order sliding mode controller, represents the nonhomogeneous term in the permanent magnet synchronous motor plant model, , represents the motor's moment of inertia, Represents a given tracking target signal, represents the homogeneous term in the permanent magnet synchronous motor plant model, , represents the damping viscosity coefficient.

[0009] Specifically, a fractional-order prediction model and a fractional-order cost function are designed in the current inner loop, including: Based on the voltage balance equation of the target permanent magnet synchronous motor in the dq coordinate system, a fractional-order differential operator is introduced to construct a fractional-order voltage balance equation in the current inner loop. A fractional-order prediction model of the fractional-order voltage balance equation is constructed using a fractional-order prediction and correction algorithm. Select the dq axis voltage vector and construct a numerical evaluation index expression of the dq axis voltage vector; Based on the expression of numerical evaluation indicators, fractional calculus theory is introduced to design a fractional cost function.

[0010] Specifically, the voltage balance equation of the target permanent magnet synchronous motor in the dq coordinate system is: in, represents the differential operator, represents the d-axis voltage in the synchronous coordinate system, represents the q-axis voltage in the synchronous coordinate system, represents the d-axis current in the synchronous coordinate system, represents the q-axis current in the synchronous coordinate system, represents the stator winding phase resistance, represents the d-axis inductance, represents the q-axis inductance, represents the mechanical angular velocity of the permanent magnet synchronous motor, Represents the flux linkage of a permanent magnet.

[0011] To further explain, the fractional-order voltage balance equation is: in, represents the stator inductance.

[0012] Specifically, the fractional order prediction model is: ; in, represents the sampling period of the target permanent magnet synchronous motor control system after discretization, represents the Gamma function, Indicates the correction factor.

[0013] Specifically, the fractional cost function is expressed as: in, represents the fractional cost, represents the termination time set by the fractional-order prediction correction algorithm, represents the start time set by the fractional order prediction correction algorithm, It means converting the sum relation in the numerical evaluation index into the fractional order when performing fractional integral operation. Indicates the q-axis current control command output by the speed outer loop control. Indicates the d-axis control command output by the speed outer loop control. represents the weight factor, Indicates the sampling time.

[0014] The above scheme of the present invention has the following beneficial effects: The present invention designs a fractional-order sliding mode surface and a fractional-order reaching law in a speed outer loop of a target permanent magnet synchronous motor, and constructs a fractional-order sliding mode controller based on the fractional-order sliding mode surface and the fractional-order reaching law; uses a dung beetle algorithm to adjust the parameters of the fractional-order sliding mode controller to obtain the optimal control parameters of the fractional-order sliding mode controller, and the fractional-order sliding mode controller generates an optimal q-axis current control instruction based on the optimal control parameters; designs a fractional-order prediction model and a fractional-order cost function in a current inner loop of the target permanent magnet synchronous motor, and constructs a fractional-order model prediction current controller based on the fractional-order prediction model and the fractional-order cost function, and the fractional-order sliding mode controller generates an optimal q-axis current control instruction based on the optimal control parameters. The model predictive current controller is used to generate an optimal stator voltage control instruction; based on the optimal q-axis current control instruction and the optimal stator voltage control instruction, the speed and current of the target permanent magnet synchronous motor are controlled respectively, so that the actual speed and current of the target permanent magnet synchronous motor track to the given speed and current; compared with the prior art, the present invention introduces a fractional-order operator into a traditional sliding mode controller and a model predictive current controller, and improves the control accuracy of the speed of the permanent magnet synchronous motor by suppressing the speed fluctuation of the permanent magnet synchronous motor, thereby providing a sufficient basis and reliability guarantee for the fault-tolerant control mechanism of the high-performance permanent magnet synchronous motor.

[0015] Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of a flow chart of an embodiment of the present invention; Figure 2 Schematic diagram of the process of the dung beetle algorithm in the embodiment of the present invention; Figure 3 is the mechanical angular velocity and the q-axis current in the synchronous coordinate system Response waveform diagram. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0019] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a locking connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0021] In view of the existing problems, the present invention provides a control method for a permanent magnet synchronous motor.

[0022] like Figure 1 As shown, an embodiment of the present invention provides a control method for a permanent magnet synchronous motor, comprising: Step 1, selecting a target permanent magnet synchronous motor, wherein the dual closed-loop control system of the target permanent magnet synchronous motor includes a speed outer loop and a current inner loop; Step 2, designing a fractional-order sliding surface and a fractional-order reaching law in the speed outer loop, and constructing a fractional-order sliding mode controller based on the fractional-order sliding surface and the fractional-order reaching law; Step 3, using the dung beetle algorithm to tune the parameters of the fractional-order sliding mode controller to obtain the optimal control parameters of the fractional-order sliding mode controller, and the fractional-order sliding mode controller generates the optimal q-axis current control command of the target permanent magnet synchronous motor based on the optimal control parameters; Step 4, designing a fractional-order prediction model and a fractional-order cost function in the current inner loop, and constructing a fractional-order model prediction current controller based on the fractional-order prediction model and the fractional-order cost function, wherein the fractional-order model prediction current controller is used to generate an optimal stator voltage control instruction for the target permanent magnet synchronous motor; Step 5: Control the speed and current of the target permanent magnet synchronous motor based on the optimal q-axis current control instruction and the optimal stator voltage control instruction, respectively, so that the actual speed and current of the target permanent magnet synchronous motor track the given speed and current.

[0023] The embodiment of the present invention takes a permanent magnet synchronous motor as a research object, and the control system of the permanent magnet synchronous motor is a double closed-loop control system, and the double closed-loops are a speed outer loop and a current inner loop.

[0024] Specifically, the fractional-order sliding surface and fractional-order reaching law are designed in the speed outer loop, including: For a given target signal, define the position tracking error and velocity tracking error; Based on the position tracking error and the speed tracking error, a fast terminal sliding surface that converges within a preset time is constructed in the speed outer loop; Constrain the parameters in the fast terminal sliding surface and introduce fractional order differential linear terms to make the fast terminal sliding surface converge and obtain the fractional order sliding surface. The design introduces the reaching law of fractional order operator and obtains the fractional order reaching law which is used to make the double closed-loop control system enter the sliding mode state.

[0025] In the embodiment of the present invention, the position tracking error is defined as and the speed tracking error is , the expression is as follows: in, Represents a given tracking target signal, represents the mechanical angle of the permanent magnet synchronous motor, represents the rate of change of a given tracking target signal, Represents the mechanical angular velocity of the permanent magnet synchronous motor; Based on the position tracking error and the speed tracking error, a fast terminal sliding surface that can converge within a limited time is constructed in the speed outer loop, which is: in, represents the fast terminal sliding surface, represents the sliding surface gain, , All represent the parameters of the fast terminal sliding surface. , are all positive odd numbers and satisfy ; By constraining parameters , The variation range of is set, and the fractional-order differential linear term is introduced to make the fast terminal sliding surface avoid singularity and achieve fast convergence, and then design the fractional-order sliding surface, whose expression is: in, represents the fractional sliding surface, represents the position tracking error, represents the speed tracking error, represents the fractional integral operator, represents the differential order, , represent positive real numbers, , All represent the parameters of the fast terminal sliding surface. .

[0026] In an embodiment of the present invention, when the tracking error of the dual closed-loop control system is far away from the equilibrium point, the exponential term in the fractional-order sliding surface is used to make the system tracking error converge quickly; and when the dual closed-loop empty flocking tracking error is close to the equilibrium point, the linear term in the fractional-order sliding surface dominates the system tracking error to converge quickly. Therefore, introducing a fractional-order integral operator in the linear term can make the fractional-order sliding surface have a faster convergence speed when it approaches the equilibrium point.

[0027] In the embodiment of the present invention, in order to ensure that the system quickly and smoothly enters the sliding mode state, a fractional-order operator is introduced into the reaching law to obtain a fractional-order reaching law, which is expressed as follows: in, represents the fractional-order reaching law, , and All represent undetermined coefficients and satisfy , , , represents the fractional-order switching term. When the value is large, the approach speed is accelerated. When s is small, the approach rate can be slowed down, thereby ensuring that the speed of approaching the sliding surface is accelerated without increasing chattering.

[0028] Specifically, the expression of the fractional-order sliding mode controller constructed by combining the fractional-order sliding mode surface and the fractional-order reaching law is: in, represents the fractional-order sliding mode controller, represents the nonhomogeneous term in the permanent magnet synchronous motor plant model, , represents the motor's moment of inertia, Represents a given tracking target signal, represents the homogeneous term in the permanent magnet synchronous motor plant model, , represents the damping viscosity coefficient.

[0029] Since the control performance of the fractional-order sliding mode controller is affected by the parameters , , , and The influence of is large, so the embodiment of the present invention uses the dung beetle algorithm to optimize and adjust these parameters, and find the optimal solution to achieve the optimal speed tracking performance of the dual closed-loop control system. The dung beetle algorithm includes rolling dung beetles, egg-hatching dung beetles, small dung beetles, and stealing dung beetles. Each group of parameters of the fractional order sliding mode controller is used as an individual in the population. The specific optimization process is as follows: First, set the maximum number of iterations and the population size; Then, the rolling ball dung beetle, egg-hatching dung beetle, small dung beetle and stealing dung beetle in the dung beetle algorithm are randomly initialized; The initial fitness values ​​of the rolling dung beetle, the egg-hatching dung beetle, the small dung beetle and the thieving dung beetle are calculated according to the objective function; Determine whether the current individual is a rolling ball dung beetle. If so, use the rolling ball dung beetle's position update mechanism to update the position of the rolling ball dung beetle. The update mechanism expression is: in, represents the randomly generated Group parameter vector In the The value at the iteration; represents the deflection coefficient, ; represents the natural coefficient, , is the worst position in the current population, is the exploration preference parameter of the search space; Otherwise, determine whether the current individual is a brooding dung beetle. If so, use the position update mechanism of the brooding dung beetle to update the position of the brooding dung beetle. The update mechanism expression is: in, Indicates The iteration A hatching location, , represents two independent random variables; Indicates the optimal position within the current population; , Indicates the lower and upper limits of the spawning area; Otherwise, determine whether the current individual is a small dung beetle. If so, use the small dung beetle position update mechanism to update the position of the small dung beetle. The update mechanism expression is: in, , represents the parameters in the fractional-order sliding mode controller The lower and upper limits of the vector value range; Represents random numbers that follow a normal distribution; Represents a random number belonging to a uniform distribution; Otherwise, determine whether the current individual is a thieving dung beetle. If so, use the thieving dung beetle position update mechanism to update the position of the thieving dung beetle. The update mechanism expression is: in, denote a constant and a random variable that follows a normal distribution, respectively; When the entire population is traversed and the maximum number of iterations is reached, the optimal control parameters of the fractional-order sliding mode controller are output.

[0030] Specifically, a fractional-order prediction model and a fractional-order cost function are designed in the current inner loop, including: Based on the voltage balance equation of the target permanent magnet synchronous motor in the dq coordinate system, a fractional-order differential operator is introduced to construct a fractional-order voltage balance equation in the current inner loop. A fractional-order prediction model of the fractional-order voltage balance equation is constructed using a fractional-order prediction and correction algorithm. Select the dq axis voltage vector and construct a numerical evaluation index expression of the dq axis voltage vector; Based on the expression of numerical evaluation indicators, fractional calculus theory is introduced to design a fractional cost function.

[0031] Specifically, the voltage balance equation of the target permanent magnet synchronous motor in the dq coordinate system is: in, represents the differential operator, represents the d-axis voltage in the synchronous coordinate system, represents the q-axis voltage in the synchronous coordinate system, represents the d-axis current in the synchronous coordinate system, represents the q-axis current in the synchronous coordinate system, represents the stator winding phase resistance, represents the d-axis inductance, represents the q-axis inductance, represents the motor mechanical angular velocity, Represents the flux linkage of a permanent magnet.

[0032] Specifically, based on the voltage balance equation of the target permanent magnet synchronous motor in the dq coordinate system, a fractional-order differential operator is introduced, and a fractional-order voltage balance equation is constructed in the current inner loop, which is: in, represents the stator inductance; Specifically, the fractional prediction correction algorithm is used to construct the fractional-order prediction model of the permanent magnet synchronous motor fractional-order voltage balance equation under the above continuous situation: ; in, represents the sampling period of the target permanent magnet synchronous motor control system after discretization, represents the Gamma function, It represents the correction coefficient, and its specific form is as follows: in, represents the current step number of the estimation correction algorithm, represents the fractional order, with q=α, Represents the index factor.

[0033] The dq axis voltage vector selected by the embodiment of the present invention is the optimal voltage vector, which is the dq axis voltage vector that minimizes the deviation between the model predicted current and the input control command current. The numerical evaluation index expression of the dq axis voltage vector is constructed as follows: in, represents the numerical evaluation index, Indicates the d-axis control command output by the speed outer loop control. represents the q-axis current control command output by the speed outer loop control. If the dual closed-loop control system adopts the magnetic field oriented control strategy, then .

[0034] Specifically, the expression of the fractional cost function is: in, represents the fractional cost, represents the termination time set by the fractional-order prediction correction algorithm, represents the start time set by the fractional order prediction correction algorithm, It means converting the sum relation in the numerical evaluation index into the fractional order when performing fractional integral operation. Indicates the q-axis current control command output by the speed outer loop control. Indicates the d-axis control command output by the speed outer loop control. represents the sampling time, Represents the weight factor and satisfies the following relationship: in, represents the Nth-order Legendre polynomial.

[0035] In the embodiment of the present invention, the numerical evaluation basis of the permanent magnet synchronous motor double closed-loop control system model is: in, Represents an array of simulation times recorded in the model, Indicates the simulation termination time in the model; It represents the input value of the speed controller, that is, the deviation between the speed reference and the feedback.

[0036] In order to verify the effectiveness of the control method provided by the embodiment of the present invention, a surface-mounted permanent magnet synchronous motor with parameters shown in Table 1 below is selected as a control object: Table 1

[0037] Given speed control command The mechanical angular velocity of the controlled object is controlled by the step wave input under the control method provided. and the q-axis current in the synchronous coordinate system The response waveform is as follows Figure 3 As shown in (a) and (b), the experiment proves that: since the step wave input belongs to a relatively slow-changing process, the motor speed feedback (actual speed) can achieve very high following accuracy when following the given speed control signal (reference); at the same time, the ripple of the q-axis current and electromagnetic torque (Electromagnetic Torque) can always be controlled within a smaller amplitude range.

[0038] The embodiment of the present invention designs a fractional-order sliding mode surface and a fractional-order reaching law in the speed outer loop of the target permanent magnet synchronous motor, and constructs a fractional-order sliding mode controller based on the fractional-order sliding mode surface and the fractional-order reaching law; uses the dung beetle algorithm to adjust the parameters of the fractional-order sliding mode controller to obtain the optimal control parameters of the fractional-order sliding mode controller, and the fractional-order sliding mode controller generates an optimal q-axis current control instruction based on the optimal control parameters; designs a fractional-order prediction model and a fractional-order cost function in the current inner loop of the target permanent magnet synchronous motor, and constructs a fractional-order model prediction current controller based on the fractional-order prediction model and the fractional-order cost function, and the fractional-order sliding mode controller generates an optimal q-axis current control instruction based on the optimal control parameters. The model predictive current controller is used to generate an optimal stator voltage control instruction; based on the optimal q-axis current control instruction and the optimal stator voltage control instruction, the speed and current of the target permanent magnet synchronous motor are controlled respectively, so that the actual speed and current of the target permanent magnet synchronous motor track to the given speed and current; compared with the prior art, the embodiment of the present invention introduces a fractional-order operator into the traditional sliding mode controller and the model predictive current controller, and improves the control accuracy of the speed of the permanent magnet synchronous motor by suppressing the speed fluctuation of the permanent magnet synchronous motor, thereby providing a sufficient basis and reliability guarantee for the fault-tolerant control mechanism of the high-performance permanent magnet synchronous motor.

[0039] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A control method for a permanent magnet synchronous motor, characterized in that: include: Step 1, selecting a target permanent magnet synchronous motor, wherein the dual closed-loop control system of the target permanent magnet synchronous motor includes a speed outer loop and a current inner loop; Step 2, designing a fractional-order sliding surface and a fractional-order reaching law in the speed outer loop, and constructing a fractional-order sliding mode controller based on the fractional-order sliding surface and the fractional-order reaching law; Step 3, using a dung beetle algorithm to tune the parameters of the fractional-order sliding mode controller to obtain the optimal control parameters of the fractional-order sliding mode controller, and the fractional-order sliding mode controller generates an optimal q-axis current control instruction of the target permanent magnet synchronous motor based on the optimal control parameters; Step 4, designing a fractional-order prediction model and a fractional-order cost function in the current inner loop, and constructing a fractional-order model prediction current controller based on the fractional-order prediction model and the fractional-order cost function, wherein the fractional-order model prediction current controller is used to generate an optimal stator voltage control instruction for the target permanent magnet synchronous motor; Step 5: Control the speed and current of the target permanent magnet synchronous motor based on the optimal q-axis current control instruction and the optimal stator voltage control instruction, so that the actual speed and current of the target permanent magnet synchronous motor track the given speed and current.

2. The control method of the permanent magnet synchronous motor according to claim 1, characterized in that: A fractional order sliding surface and a fractional order reaching law are designed in the speed outer loop, including: For a given target signal, define the position tracking error and velocity tracking error; Based on the position tracking error and the speed tracking error, constructing a fast terminal sliding mode surface that converges within a preset time in the speed outer loop; Constraining parameters in the fast terminal sliding surface and introducing fractional-order differential linear terms so that the fast terminal sliding surface converges to obtain a fractional-order sliding surface; The design introduces a reaching law of a fractional-order operator, and obtains a fractional-order reaching law for making the double closed-loop control system enter a sliding mode state.

3. The control method of the permanent magnet synchronous motor according to claim 2, characterized in that: The expression of the fractional sliding surface is: in, represents the fractional sliding surface, represents the position tracking error, represents the speed tracking error, represents the fractional integral operator, represents the differential order, , represent positive real numbers, , All represent the parameters of the fast terminal sliding surface. .

4. The control method of the permanent magnet synchronous motor according to claim 3, characterized in that: The expression of the fractional-order reaching law is: in, represents the fractional-order reaching law, , and All represent undetermined coefficients, represents the fractional-order switching term.

5. The control method of the permanent magnet synchronous motor according to claim 4, characterized in that: The expression of the fractional-order sliding mode controller is: ； in, represents the fractional-order sliding mode controller, represents the nonhomogeneous term in the permanent magnet synchronous motor plant model, , represents the motor's moment of inertia, Represents a given tracking target signal, represents the homogeneous term in the permanent magnet synchronous motor plant model, , represents the damping viscosity coefficient.

6. The control method of the permanent magnet synchronous motor according to claim 5, characterized in that: A fractional-order prediction model and a fractional-order cost function are designed in the current inner loop, including: Based on the voltage balance equation of the target permanent magnet synchronous motor in the dq coordinate system, a fractional-order differential operator is introduced to construct a fractional-order voltage balance equation in the current inner loop; A fractional-order prediction model of the fractional-order voltage balance equation is constructed by using a fractional-order prediction and correction algorithm; Selecting a dq axis voltage vector and constructing a numerical evaluation index expression of the dq axis voltage vector; Based on the numerical evaluation index expression, the fractional calculus theory is introduced to design a fractional cost function.

7. The control method of the permanent magnet synchronous motor according to claim 6, characterized in that: The voltage balance equation of the target permanent magnet synchronous motor in the dq coordinate system is: in, represents the differential operator, represents the d-axis voltage in the synchronous coordinate system, represents the q-axis voltage in the synchronous coordinate system, represents the d-axis current in the synchronous coordinate system, represents the q-axis current in the synchronous coordinate system, represents the stator winding phase resistance, represents the d-axis inductance, represents the q-axis inductance, represents the mechanical angular velocity of the permanent magnet synchronous motor, Represents the flux linkage of a permanent magnet.

8. The control method of the permanent magnet synchronous motor according to claim 7, characterized in that: The fractional-order voltage balance equation is: in, represents the stator inductance.

9. The control method of the permanent magnet synchronous motor according to claim 8, characterized in that: The fractional order prediction model is: in, represents the sampling period of the target permanent magnet synchronous motor control system after discretization, represents the Gamma function, Indicates the correction factor.

10. The control method of the permanent magnet synchronous motor according to claim 9, characterized in that: The expression of the fractional cost function is: in, represents the fractional cost, represents the termination time set by the fractional-order prediction correction algorithm, represents the start time set by the fractional order prediction correction algorithm, It means converting the sum relation in the numerical evaluation index into the fractional order when performing fractional integral operation. Indicates the q-axis current control command output by the speed outer loop control. Indicates the d-axis control command output by the speed outer loop control. represents the weight factor, Indicates the sampling time.

Images