High dynamic response model-free predictive current control method and device based on independent constraint conditions

Abstract

The invention provides a high-dynamic-response model-free predictive current control method and device based on independent constraint conditions, and relates to the technical field of current prediction of a permanent magnet synchronous motor. Motor operation parameters in a period are collected for a PMSM driving system, a hyperlocal model of the PMSM driving system is established, and a high-dynamic-response model-free predictive current control method and device based on the independent constraint conditions are established; and discretizing the model to obtain a stator direct-axis predicted current and a stator quadrature-axis predicted current, designing a stator direct-axis current independent cost function and a stator quadrature-axis current independent cost function to obtain a voltage vector rectangular constraint space, and according to the dynamic change trend of four regions of the voltage vector rectangular constraint space on four kinds of dq-axis current, calculating the dynamic change trend of the four kinds of dq-axis current. And constructing a cost function constraint of voltage feedback, obtaining a stator direct-axis reference voltage and a stator quadrature-axis reference voltage of the voltage vector under a two-phase rotating coordinate system, and obtaining a three-phase actual applied voltage of the stator of the permanent magnet synchronous motor through coordinate change, thereby realizing independent constraint-based high-dynamic model-free predictive current control of the permanent magnet synchronous motor.

Description

Technical Field

[0001] The present invention relates to the technical field of current prediction of permanent magnet synchronous motors, and in particular to a high dynamic response model-free prediction current control method and device based on independent constraints. Background Art

[0002] When the PMSM drive system of a permanent magnet synchronous motor is running at high speed, it is very easy for the inverter reference voltage amplitude to exceed the maximum voltage that the inverter can output during the dynamic process, resulting in voltage saturation, which inevitably affects the reference voltage and cannot be output linearly, resulting in a significant decrease in the dynamic response speed of the drive system current. Therefore, it is one of the future application trends to reasonably set the inverter reference voltage vector in the voltage space to restrict voltage saturation and achieve high dynamic and fast response of the stator current of the PMSM drive system.

[0003] At present, one of the solutions to achieve high dynamic and fast current response is to fix the phase of the inverter reference voltage vector, reduce the voltage vector amplitude to the maximum limit voltage range, increase the voltage margin, and improve the stator current response speed of the drive system. However, since the voltage vector does not consider the coupling between the orthogonal axes, it may cause a decrease in the dynamic response speed of the current.

[0004] There is also a solution for dynamic adjustment and optimization of the direct-axis reference current. The fundamental reason for the reduction in current response speed when the PMSM drive system is running at high speed is that the quadrature-axis voltage margin used to increase the quadrature-axis stator current is insufficient. By designing a quadrature-axis voltage feedback outer loop, the direct-axis reference current is dynamically adjusted to increase the quadrature-axis voltage and improve the response speed of the stator quadrature-axis current. However, the essence of this solution to increase the quadrature-axis voltage margin is to provide additional demagnetization current in the dynamic process. Therefore, the stator direct-axis current must be limited to ensure the safety of the drive system operation.

[0005] The idea of ​​using DTC to directly control the angle between the stator and rotor flux to improve the dynamic response of the torque is to combine the FOC model-based idea with the DTC control method to obtain the MPTC model predictive torque control. MPTC evaluates each inverter voltage vector through a cost function to obtain the optimal reference voltage vector and improve the high dynamic response of the stator current of the drive system. However, due to the limitation of hardware equipment, the prediction length of MPTC cannot cover the entire dynamic process, resulting in limited improvement in the dynamic current response performance.

[0006] The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not constitute the prior art that is already known to one of ordinary skill in the art. Summary of the invention

[0007] The object of the present invention is to provide a high dynamic response model-free predictive current control method and device based on independent constraints to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A high dynamic response model-free predictive current control method based on independent constraints, the specific steps include:

[0010] Step 1: Set the sampling period of the PMSM drive system to T, and obtain the PMSM drive system at the kth sampling period T k The actual stator direct axis current i d (k), kth sampling period T k The actual stator quadrature axis current i q (k), kth sampling period T k The actual rotor position angle θ r (k) and the kth sampling period T k The DC power supply voltage u s (k), and due to the control timing delay applied to the kth control cycle T k Stator direct axis reference voltage Stator quadrature axis reference voltage

[0011] Step 2: By obtaining the kth sampling period T k The stator direct axis estimate and the kth sampling period T k The stator quadrature axis estimator with disturbance Establish a super-local model of PMSM drive system;

[0012] Step 3: Estimated stator direct axis values ​​of adjacent control cycles and stator quadrature axis estimate As a constant, in the kth sampling period T k To the k+1th sampling period T k+1 The first-order forward Euler method is used to discretize the PMSM drive system super-local model to obtain the k+1th sampling period T k+1 The predicted stator direct axis current i d (k+1) and the stator quadrature axis predicted current i q (k+1);

[0013] Step 4: In the k+1th sampling period T k+1 To the k+2th sampling period T k+2 The first-order forward Euler method is used to discretize the PMSM drive system super-local model to obtain the k+2 sampling period Tk+2 The predicted stator direct axis current i d (k+2) and the stator quadrature axis predicted current i q (k+2);

[0014] Step 5: Design an independent cost function for stator direct-axis current related to current tracking error and the stator quadrature-axis current independent cost function According to the stator direct axis cost function and stator quadrature axis cost function Obtain the voltage vector rectangular constraint space;

[0015] Step 6: According to the four regions of the voltage vector rectangular constraint space, the stator direct axis current i d (k) and stator quadrature axis current i q (k) Different effects of response, construct the cost function constraint of voltage feedback, select the reference voltage vector by obtaining the d-axis adaptive cost function constraint, and calculate the size of the output voltage vector to obtain the stator direct axis reference voltage of the voltage vector in the two-phase rotating coordinate system and stator quadrature axis reference voltage

[0016] Step 7: Use the minimum phase error method to convert the stator direct axis reference voltage and stator quadrature axis reference voltage The amplitude is reduced to the inscribed circle of the voltage hexagon to obtain the actual applied voltage u on the stator direct axis d (k) and the actual applied voltage u on the stator quadrature axis q (k), the actual voltage u is applied to the stator direct axis d (k) and the actual applied voltage u on the stator quadrature axis q (k) Perform coordinate changes to obtain the actual applied voltage u of the three-phase stator of the permanent magnet synchronous motor a (k),u b (k),u c (k) Realize independent constraint-based high dynamic model-free predictive current control of permanent magnet synchronous motor;

[0017] The stator direct axis reference voltage of the voltage vector in the two-phase rotating coordinate system is obtained and stator quadrature axis reference voltage The specific steps are:

[0018] Step 6a: The voltage vector rectangular constraint space is divided into four regions i d ↓i q ↓、i d ↑i q ↓、i d ↓i q ↑and i d↑i q ↑, has different effects on the dq axis current response, where i d ↑ indicates reference voltage Make the d-axis current change towards the reference current; i d ↓ indicates reference voltage Make the d-axis current change negatively toward the reference current; i q ↑ indicates reference voltage Make the q-axis current change towards the reference current; i q ↓ indicates reference voltage Make the q-axis current change negatively toward the reference current;

[0019] Step 6b: The size of will change the range of the voltage vector rectangular constraint space. Based on the principle of improving the high dynamic response speed of the stator current, the d-axis current changes negatively toward the reference current, increasing the q-axis voltage margin to avoid voltage saturation, and obtaining the dq-axis current independent setting constraints, as shown in the following formula:

[0020]

[0021] Where k is the d-axis feedback gain, The q-axis reference voltage generated by the current regulator, u q The actual applied voltage is obtained after the voltage saturation occurs on the q-axis;

[0022] Step 6c: According to the d-axis current changing towards the reference current in the negative direction, that is, The rectangular constraint space converges to the straight line segment, and the reference voltage and The analytical expression of is obtained by using Park transformation Park variations are:

[0023]

[0024] Furthermore, the actual stator direct axis current i d (k), actual stator quadrature axis current i q (k), actual rotor position angle θ r (k), DC power supply voltage u s (k) The specific steps of obtaining are:

[0025] Step 1a: Use the current sensor to detect and obtain the kth sampling period T k The stator three-phase current a phase current i a (k) and the kth sampling period T k The b-phase current i b (k);

[0026] Step 1b: Use the position sensor to detect and obtain the kth sampling period T k The actual rotor position angle θ r (k);

[0027] Step 1c: Use the voltage sensor to detect and obtain the kth sampling period T k DC power supply voltage u s (k);

[0028] Step 1d: Use Clark's formula to calculate the phase a current i a (k), b-phase current i b (k) Perform equal amplitude transformation to obtain the kth sampling period T of the permanent magnet synchronous motor based on the two-phase stationary coordinate system k The actual stator α-axis current i α (k) and the kth sampling period T k The actual stator β-axis current i β (k), the transformation formula is;

[0029]

[0030] Wherein, k≥1 and k is a positive integer, k=1,2,3,….

[0031] Furthermore, the specific steps of establishing the PMSM drive system super-local model are as follows: define n as the data window length, and according to the kn-2th sampling period T k-2-n Stator direct axis reference voltage Until the k-2th sampling period T k-2 Stator direct axis reference voltage The kn-2th sampling period T k-2-n Stator quadrature axis reference voltage Until the k-2th sampling period T k-2 Stator quadrature axis reference voltage knth sampling period T k-n The actual stator direct axis current i d (kn) to the kth sampling period T k The actual stator direct axis current i d (k), knth sampling period T k-n The actual stator quadrature axis current i q (kn) to the kth sampling period T k The actual stator quadrature axis current i q (k), calculate and obtain the kth sampling period T k Estimated value of stator direct axis and the kth sampling period T k Estimated value of stator quadrature axis

[0032] The stator direct axis estimated value and stator quadrature axis estimate The calculation formulas are:

[0033]

[0034] Where: m is the sampling point of the kth control cycle, α d is the stator direct axis voltage coefficient, α q is the stator quadrature axis voltage coefficient. When m―n≤0, let i d (kn) = 0, i q (kn) = 0,

[0035] The calculation formula of the super-local model of the PMSM drive system is:

[0036]

[0037] Among them, i d is the stator direct axis current, i q is the stator quadrature axis current, α d is the stator direct axis voltage coefficient, α q is the stator quadrature-axis voltage coefficient.

[0038] Furthermore, in the kth sampling period T k To the k+1th sampling period T k+1 The specific formula for discretizing the hyperlocal model of the PMSM drive system using the first-order forward Euler method is:

[0039]

[0040] Among them, i d (k+1) k+1th sampling period T k+1 The predicted stator direct axis current at time i q (k+1) k+1th sampling period T k+1 The predicted stator quadrature axis current is The kth control period T k The actual voltage applied to the stator direct axis is, The kth control period T k The actual applied voltage on the stator quadrature axis, α d is the stator direct axis voltage coefficient, α q is the stator quadrature-axis voltage coefficient.

[0041] Furthermore, in the k+1th sampling period T k+1 To the k+2th sampling period Tk+2 The calculation formula for discretizing the super-local model of the PMSM drive system using the first-order forward Euler method is:

[0042]

[0043] Among them, i d (k+2) k+2th sampling period T k+2 The predicted stator direct axis current at time i q (k+2) k+2th sampling period T k+2 The predicted stator quadrature axis current is The k+1th control period T k+1 The actual voltage applied to the stator direct axis is, The k+1th control period T k+1 The actual applied voltage on the stator quadrature axis, α d is the stator direct axis voltage coefficient, α q is the stator quadrature-axis voltage coefficient.

[0044] Furthermore, the design is related to the stator direct axis current independent cost function of the current tracking error and the stator quadrature-axis current independent cost function According to the stator direct axis cost function and stator quadrature axis cost function The specific steps to obtain the voltage vector rectangular constraint space are:

[0045] Step 5a: Design independent cost function for stator direct-axis current Stator quadrature-axis current independent cost function

[0046] The stator direct axis current independent cost function Stator quadrature-axis current independent cost function The mathematical formula is;

[0047]

[0048] in, is the stator direct axis reference current, is the stator quadrature axis reference current, i d (k+2) is the k+2th sampling period T k+2 Predicted stator direct axis current, i q (k+2) is the k+2th sampling period T k+2 Stator quadrature axis predicted current;

[0049] Step 5b: According to the k+1th control period T k+1 The actual applied voltage on the stator direct axis and the k+1th control cycle Tk+1 The actual applied voltage on the stator quadrature axis After Park transformation, and Transformed into a two-phase stationary coordinate system and

[0050] The formula after Park transformation is:

[0051]

[0052] Step 5c: According to the two-phase stationary coordinate system and The current independent cost function is obtained, and the independent cost function is:

[0053]

[0054] Step 5d: Based on the stator direct axis reference current and the corresponding stator direct axis predicted current i d Three relationships of (k+2); greater than 0, equal to 0 and less than 0; stator quadrature axis reference current The corresponding stator quadrature axis predicted current i q Three relationships of (k+2): greater than 0, equal to 0, and less than 0; nine combinations are obtained, as described in the following formula:

[0055]

[0056] Step 5e: Substitute the independent cost functions into the stator direct axis reference current and the corresponding stator direct axis predicted current i d (k+2) relational formula, stator quadrature axis reference current The corresponding stator quadrature axis predicted current i q (k+2) relational formula:

[0057]

[0058] Step 5f: Using the inequality relationship of the following formula, the influence of different regions on the d-axis, q-axis and dq-axis currents in the αβ-axis two-phase rotating coordinate system space is obtained;

[0059]

[0060] Step 5g: According to the above equation, we can obtain and The corresponding straight line equation in the αβ axis is:

[0061]

[0062] in,

[0063] k q =tanθ r ,

[0064] in accordance with The linear equation obtains four straight lines in the αβ axis two-phase rotating coordinate system space, forming a rectangular constraint space for the voltage vector. When different values ​​are taken, the range of the voltage vector rectangular constraint space will change.

[0065] The present invention also provides a high dynamic response model-free predictive current control device based on independent constraints, the current control device is used to execute the above-mentioned high dynamic response model-free predictive current control method based on independent constraints, comprising:

[0066] The current sensor is used to detect and obtain the kth sampling period T k The stator three-phase current a phase current i a (k) and the kth sampling period T k The b-phase current i b (k);

[0067] A voltage sensor is used to detect and obtain the kth sampling period T k DC power supply voltage u s (k);

[0068] The position sensor is used to detect and obtain the kth sampling period T k The actual rotor position angle θ r (k);

[0069] The first conversion module is used to convert the stator a phase current and i phase current provided by the current sensor. a (k) Stator b phase current i b (k) Using Clark coordinate transformation, the three-phase stationary coordinate system is converted into a two-phase stationary coordinate system to obtain the actual stator α-axis current i α (k) and the actual stator β-axis current i β (k), and the position sensor provides the actual rotor position angle θ r (k) Perform Park coordinate transformation to convert the two-phase stationary coordinate system into the two-phase rotating coordinate system to obtain the actual stator direct axis current i d (k) and the actual stator quadrature axis current i q (k);

[0070] The delay compensation module generates the stator current of the k+2th sampling period by setting n as the data window length and the reference voltage of the k-2th sampling period. The delay compensation module generates the stator current of the k+2th sampling period by setting n as the data window length and the reference voltage of the k-2th sampling period and the stator current of the k+2th sampling period. k-2-n Stator direct axis reference voltage Until the k-2th sampling period T k-2 Stator direct axis reference voltage knth sampling period T k-n The actual stator direct axis current i d (kn) to the kth sampling period T k The actual stator direct axis current i d (k) is processed to obtain the k+1th sampling period T k+1 Stator direct axis predicted current i d (k+1), the delay compensation module performs the delay compensation on the kn-2th sampling period T k-2-n Stator quadrature axis reference voltage Until the k-2th sampling period T k-2 Stator quadrature axis reference voltage knth sampling period T k-n The actual stator quadrature axis current i q (kn) to the kth sampling period T k The actual stator quadrature axis current i q (k) is processed to obtain the k+1th sampling period T k+1 Stator quadrature axis predicted current i q (k+1);

[0071] Current regulator, the current regulator is used to design a stator direct axis current independent cost function is the stator direct axis reference current and the k+2th sampling period T k+2 Stator direct axis predicted current i d The square of the error between (k+2) Design stator quadrature-axis current cost function is the stator quadrature axis reference current and the k+2th sampling period T k+2 Stator quadrature axis predicted current i q The square of the error between (k+2)

[0072] And according to the set stator direct axis current independent cost function and the stator quadrature-axis current independent cost function The rectangular constraint space of the voltage vector in the αβ coordinate system is processed, and the influence of the four different regions in the rectangular constraint space on the d-axis and q-axis current responses is used to select the rectangular constraint space partition that makes the d-axis current change negatively toward the reference current and the q-axis current change negatively toward the reference current, and the output voltage vector is calculated to obtain the kth sampling period T k Stator direct axis reference voltage and the kth sampling period T k Stator quadrature axis reference voltage

[0073] The phase error module uses the minimum phase error method to apply the phase error to the kth sampling period T k Stator direct axis reference voltage and the kth sampling period T k Stator quadrature axis reference voltage Processing is performed to obtain the kth sampling period T k Actual voltage applied to stator direct axis u d (k) and the kth sampling period T k The actual applied voltage u of the stator quadrature axis q (k);

[0074] The second conversion module is used to convert the stator direct axis actual applied voltage u d (k) and the actual applied voltage u on the stator quadrature axis q (k) Perform coordinate changes to obtain the actual applied voltage u of the three-phase stator of the permanent magnet synchronous motor a (k) and u b (k) and u c (k) and transmitted to the inverter, a high dynamic response model-free predictive current control of the permanent magnet synchronous motor based on independent constraints is presented.

[0075] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention establishes a super-local model of the PMSM drive system by collecting the motor operating parameters within a period of the PMSM drive system, and discretizes the local model to obtain the stator direct-axis predicted current and the stator quadrature-axis predicted current, and obtains the voltage vector rectangular constraint space by designing the stator direct-axis current independent cost function and the stator quadrature-axis current independent cost function, and constructs the cost function constraint of the voltage feedback according to the dynamic change trends of the four dq-axis currents in the four regions of the voltage vector rectangular constraint space, and obtains the stator direct-axis reference voltage and the stator quadrature-axis reference voltage of the voltage vector in a two-phase rotating coordinate system, and obtains the actual applied voltage of the three-phase stator of the permanent magnet synchronous motor through the coordinate change, thereby realizing the high dynamic model-free predictive current control of the permanent magnet synchronous motor based on independent constraints.

[0076] Based on the super-local model of the PMSM drive system, the present invention derives the rectangular constraint space in the αβ axis related to the dynamic response of the dq axis current, and analyzes and obtains four dynamic change trends of the dq axis current corresponding to the reference voltage vector located in the four regions of the space. The reference voltage vector selection basis that can improve the response speed of the q axis stator current under voltage saturation is given, and the current dynamic response speed is improved under the voltage saturation state caused by insufficient voltage margin.

[0077] The present invention also constructs a cost function constraint generation scheme based on voltage feedback, which can adaptively obtain the d-axis cost function constraint according to the voltage saturation degree, and combines the selection basis of the reference voltage vector, by making the d-axis current change toward the reference current negatively, effectively increasing the q-axis voltage margin, and realizing the high dynamic and fast response of the q-axis stator current of the PMSM drive system, which can not only realize the independent control of the dq-axis current accuracy, but also effectively improve the dynamic response speed of the q-axis stator current of the PMSM drive system under the condition of voltage saturation. In addition, the proposed independent constraint high dynamic response model-free predictive current control method has the same dynamic and steady-state control structure, can realize the smooth switching between the dynamic and steady-state control of the system, and the system structure is simpler. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 It is a schematic diagram of the overall method flow of the present invention;

[0079] Figure 2 It is a schematic diagram of the rectangular constraint space of the four quadrants of the αβ axis, i.e., the rectangular constraints generated according to the independent cost function constraints;

[0080] Figure 3 The influence of the four regional spaces in the rectangular constraint space on the dq axis current response;

[0081] Figure 4 It is a structural schematic diagram of the control device of the present invention;

[0082] Figure 5 The current response curve of the present invention when K=0.02, K=0.11, K=0.3;

[0083] Figure 6 The current response curve of OS-MPC is shown when the speed is 400 rpm, the DC bus voltage is 48 V, and the q-axis reference current is stepped to 26.7 A;

[0084] Figure 7 The current response curve of the present invention is 400 rpm, the DC bus voltage is 48 V, and the q-axis reference current is stepped to 26.7 A;

[0085] Figure 8The current response curve of the present invention is when the speed is 200 rpm, the DC bus voltage is 24 V, and the q-axis reference current is stepped to 20 A;

[0086] Fig. 9 The current response curve of the present invention is shown in FIG. 1 , when the rotation speed is 200 rpm, the DC bus voltage is 24 V, and the q-axis reference current is stepped to 20 A. DETAILED DESCRIPTION

[0087] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0088] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0089] Example:

[0090] See also Figure 1-3 , the present invention provides a technical solution:

[0091] A high dynamic response model-free predictive current control method based on independent constraints, characterized in that the specific steps include:

[0092] Step 1: Set the sampling period of the PMSM drive system to T, and obtain the PMSM drive system at the kth sampling period T k The actual stator direct axis current i d (k), kth sampling period T k The actual stator quadrature axis current i q (k), kth sampling period T k The actual rotor position angle θ r (k) and the kth sampling period T k The DC power supply voltage u s (k), and due to the control timing delay applied to the kth control cycle T k Stator direct axis reference voltage Stator quadrature axis reference voltage

[0093] The PMSM drive system is composed of an inverter, a DC power supply and a current controller, and the current controller includes a current sensor, a position sensor, a voltage sensor, a first conversion module, a delay supplement module, a current regulator, a phase error module, and a second conversion module.

[0094] In this embodiment, the actual stator direct axis current i d (k), actual stator quadrature axis current i q (k), actual rotor position angle θ r (k), DC power supply voltage u s (k) The specific steps of obtaining are:

[0095] Step 1a: Use the current sensor to detect and obtain the kth sampling period T k The stator three-phase current a phase current i a (k) and the kth sampling period T k The b-phase current i b (k);

[0096] Step 1b: Use the position sensor to detect and obtain the kth sampling period T k The actual rotor position angle θ r (k);

[0097] Step 1c: Use the voltage sensor to detect and obtain the kth sampling period T k DC power supply voltage u s (k);

[0098] Step 1d: Use Clark's formula to calculate the phase a current i a (k), b-phase current i b (k) Perform equal amplitude transformation to obtain the kth sampling period T of the permanent magnet synchronous motor based on the two-phase stationary coordinate system k The actual stator α-axis current i α (k) and the kth sampling period T k The actual stator β-axis current i β (k), the transformation formula is;

[0099]

[0100] Among them, k≥1 and k is a positive integer, k=1,2,3,…

[0101] Step 2: By obtaining the kth sampling period T k The stator direct axis estimate and the kth sampling period T kThe stator quadrature axis estimator with disturbance Establish a hyperlocal model of the PMSM drive system.

[0102] In this embodiment, the specific steps of establishing the PMSM drive system super-local model are: define n as the data window length, according to the kn-2th sampling period T k-2-n Stator direct axis reference voltage Until the k-2th sampling period T k-2 Stator direct axis reference voltage The kn-2th sampling period T k-2-n Stator quadrature axis reference voltage Until the k-2th sampling period T k-2 Stator quadrature axis reference voltage knth sampling period T k-n The actual stator direct axis current i d (kn) to the kth sampling period T k The actual stator direct axis current i d (k), knth sampling period T k-n The actual stator quadrature axis current i q (kn) to the kth sampling period T k The actual stator quadrature axis current i q (k), calculate and obtain the kth sampling period T k Estimated value of stator direct axis and the kth sampling period T k Estimated value of stator quadrature axis

[0103] The stator direct axis estimated value and stator quadrature axis estimate The calculation formulas are:

[0104]

[0105] Among them, m is the sampling point of the kth control cycle, α d is the stator direct axis voltage coefficient, α q is the stator quadrature axis voltage coefficient. When m―n≤0, let i d (kn) = 0, i q (kn) = 0,

[0106] The calculation formula of the super-local model of the PMSM drive system is:

[0107]

[0108] Among them, i dis the stator direct axis current, i q is the stator quadrature axis current, α d is the stator direct axis voltage coefficient, α q is the stator quadrature-axis voltage coefficient.

[0109] Step 3: Estimated stator direct axis values ​​of adjacent control cycles and stator quadrature axis estimate As a constant, in the kth sampling period T k To the k+1th sampling period T k+1 The first-order forward Euler method is used to discretize the PMSM drive system super-local model to obtain the k+1th sampling period T k+1 The predicted stator direct axis current i d (k+1) and the stator quadrature axis predicted current i q (k+1).

[0110] In this embodiment, in the kth sampling period T k To the k+1th sampling period T k+1 The specific formula for discretizing the hyperlocal model of the PMSM drive system using the first-order forward Euler method is:

[0111]

[0112] Among them, i d (k+1) k+1th sampling period T k+1 The predicted stator direct axis current at time i q (k+1) k+1th sampling period T k+1 The predicted stator quadrature axis current is The kth control period T k The actual voltage applied to the stator direct axis is, The kth control period T k The actual applied voltage on the stator quadrature axis, α d is the stator direct axis voltage coefficient, α q is the stator quadrature-axis voltage coefficient.

[0113] Step 4: In the k+1th sampling period T k+1 To the k+2th sampling period T k+2 The first-order forward Euler method is used to discretize the PMSM drive system super-local model to obtain the k+2 sampling period T k+2 The predicted stator direct axis current i d (k+2) and the stator quadrature axis predicted current i q (k+2);

[0114] In this embodiment, in the k+1th sampling period T k+1To the k+2th sampling period T k+2 The calculation formula for discretizing the super-local model of the PMSM drive system using the first-order forward Euler method is:

[0115]

[0116] Among them, i d (k+2) k+2th sampling period T k+2 The predicted stator direct axis current at time i q (k+2) k+2th sampling period T k+2 The predicted stator quadrature axis current is The k+1th control period T k+1 The actual voltage applied to the stator direct axis is, The k+1th control period T k+1 The actual applied voltage on the stator quadrature axis, α d is the stator direct axis voltage coefficient, α q is the stator quadrature-axis voltage coefficient.

[0117] Step 5: Design an independent cost function for stator direct-axis current related to current tracking error and the stator quadrature-axis current independent cost function According to the stator direct axis cost function and stator quadrature axis cost function Obtain the voltage vector rectangular constraint space.

[0118] In this embodiment, the design current tracking error related stator direct axis current independent cost function and the stator quadrature-axis current independent cost function According to the stator direct axis cost function and stator quadrature axis cost function The specific steps to obtain the voltage vector rectangular constraint space are:

[0119] Step 5a: Design independent cost function for stator direct-axis current Stator quadrature-axis current independent cost function

[0120] The stator direct axis current independent cost function Stator quadrature-axis current independent cost function The mathematical formula is;

[0121]

[0122] in, is the stator direct axis reference current, is the stator quadrature axis reference current, i d (k+2) is the k+2th sampling period Tk+2 Predicted stator direct axis current, i q (k+2) is the k+2th sampling period T k+2 Stator quadrature axis predicted current;

[0123] Step 5b: According to the k+1th control period T k+1 The actual applied voltage on the stator direct axis and the k+1th control cycle T k+1 The actual applied voltage on the stator quadrature axis After Park transformation, and Transformed into a two-phase stationary coordinate system and

[0124] The formula after Park transformation is:

[0125]

[0126] Step 5c: According to the two-phase stationary coordinate system and The current independent cost function is obtained, and the independent cost function is:

[0127]

[0128] Step 5d: Based on the stator direct axis reference current and the corresponding stator direct axis predicted current i d Three relationships of (k+2); greater than 0, equal to 0 and less than 0; stator quadrature axis reference current The corresponding stator quadrature axis predicted current i q Three relationships of (k+2): greater than 0, equal to 0, and less than 0; nine combinations are obtained, as described in the following formula:

[0129]

[0130] Step 5e: Substitute the independent cost functions into the stator direct axis reference current and the corresponding stator direct axis predicted current i d (k+2) relational formula, stator quadrature axis reference current The corresponding stator quadrature axis predicted current i q (k+2) relational formula:

[0131]

[0132] Step 5f: Using the inequality relationship of the following formula, the influence of different regions on the d-axis, q-axis and dq-axis currents in the αβ-axis two-phase rotating coordinate system space is obtained;

[0133]

[0134] in accordance with When θ r When located in the four quadrants of the αβ axis, the reference voltage Component on the αβ axis and The three conditions that are satisfied can have different effects on the d-axis current response, as shown in Table 1;

[0135] Table 1

[0136]

[0137] θ r The relationship between the d-axis current variation trend and the spatial area of ​​the αβ coordinate system when the value range is different;

[0138] in, i d ↓ indicates the area where the reference voltage vector causes the d-axis current to change in the negative direction of the reference current, i d ↑ indicates the area where the reference voltage vector causes the d-axis current to change in the positive direction of the reference current, and i d → represents the region where the reference voltage vector causes the d-axis current to change toward the reference current.

[0139] in accordance with When θ r When located in the four quadrants of the αβ axis, the reference voltage Component on the αβ axis and The three conditions that are satisfied can have different effects on the q-axis current response, as shown in Table 2;

[0140] Table 2

[0141]

[0142] θ r The relationship between the q-axis current variation trend and the spatial area of ​​the αβ coordinate system when the value range is different;

[0143] in, i q ↓ indicates the area where the reference voltage vector causes the q-axis current to change in the negative direction of the reference current. On the contrary, i q ↑ indicates the area where the voltage vector causes the q-axis current to change in the positive direction toward the reference current, and i q →The area where the voltage vector will cause the q-axis current to change in the negative direction towards the reference current.

[0144] Step 5g: According to the above equation, we can obtain and The corresponding straight line equation in the αβ axis is:

[0145]

[0146] in,

[0147] k q =tanθ r ,

[0148] in accordance with The linear equation obtains four straight lines in the αβ axis two-phase rotating coordinate system space, forming the following Figure 2 The voltage vector rectangular constraint space shown in the figure is When different values ​​are taken, the range of the voltage vector rectangular constraint space will change.

[0149] Step 6: According to the four regions of the voltage vector rectangular constraint space, the stator direct axis current i d (k) and stator quadrature axis current i q (k) Different effects of response, construct the cost function constraint of voltage feedback, select the reference voltage vector by obtaining the d-axis adaptive cost function constraint, and calculate the size of the output voltage vector to obtain the stator direct axis reference voltage of the voltage vector in the two-phase rotating coordinate system and stator quadrature axis reference voltage

[0150] In this embodiment, the stator direct axis reference voltage of the voltage vector in the two-phase rotating coordinate system is obtained. and stator quadrature axis reference voltage The specific steps are:

[0151] Step 6a: Figure 3 The voltage vector rectangular constraint space shown is divided into four regions i d ↓i q ↓、i d ↑i q ↓、i d ↓i q ↑andi d ↑i q ↑, has different effects on the dq axis current response, where i d ↑ indicates reference voltage Make the d-axis current change towards the reference current; i d ↓ indicates reference voltage Make the d-axis current change negatively toward the reference current; i q ↑ indicates reference voltage Make the q-axis current change towards the reference current; i q ↓ indicates reference voltage Make the q-axis current change negatively toward the reference current;

[0152] Step 6b: The size of will change the range of the voltage vector rectangular constraint space. Based on the principle of improving the high dynamic response speed of the stator current, the d-axis current changes negatively toward the reference current, increasing the q-axis voltage margin to avoid voltage saturation, and obtaining the dq-axis current independent setting constraints, as shown in the following formula:

[0153]

[0154] Where k is the d-axis feedback gain, The q-axis reference voltage generated by the current regulator, u q The actual applied voltage is obtained after the voltage saturation occurs on the q-axis;

[0155] Step 6c: According to the d-axis current changing towards the reference current in the negative direction, that is, The rectangular constraint space converges to the straight line segment, and the reference voltage and The analytical expression of is obtained by using Park transformation Park variations are:

[0156]

[0157] Step 7: Use the minimum phase error method to convert the stator direct axis reference voltage and stator quadrature axis reference voltage The amplitude is reduced to the inscribed circle of the voltage hexagon to obtain the actual applied voltage u on the stator direct axis d (k) and the actual applied voltage u on the stator quadrature axis q (k), the actual voltage u is applied to the stator direct axis d (k) and the actual applied voltage u on the stator quadrature axis q (k) Perform coordinate changes to obtain the actual applied voltage u of the three-phase stator of the permanent magnet synchronous motor a (k) and u b (k) and u c (k) Realize independent constraint-based high dynamic model-free predictive current control of permanent magnet synchronous motor.

[0158] See also Figure 4 The present invention further provides a high dynamic response model-free predictive current control device based on independent constraints, the current control device is used to execute the above-mentioned high dynamic response model-free predictive current control method based on independent constraints, comprising:

[0159] The current sensor is used to detect and obtain the kth sampling period T k The stator three-phase current a phase current i a (k) and the kth sampling period T k The b-phase current i b (k);

[0160] A voltage sensor is used to detect and obtain the kth sampling period T k DC power supply voltage u s (k);

[0161] The position sensor is used to detect and obtain the kth sampling period T k The actual rotor position angle θ r (k);

[0162] The first conversion module is used to convert the stator a phase current and i phase current provided by the current sensor. a (k) Stator b phase current i b (k) Using Clark coordinate transformation, the three-phase stationary coordinate system is converted into a two-phase stationary coordinate system to obtain the actual stator α-axis current i α (k) and the actual stator β-axis current i β (k), and the position sensor provides the actual rotor position angle θ r (k) Perform Park coordinate transformation to convert the two-phase stationary coordinate system into the two-phase rotating coordinate system to obtain the actual stator direct axis current i d (k) and the actual stator quadrature axis current i q (k);

[0163] The delay compensation module generates the stator current of the k+2th sampling period by setting n as the data window length and the reference voltage of the k-2th sampling period. The delay compensation module generates the stator current of the k+2th sampling period by setting n as the data window length and the reference voltage of the k-2th sampling period and the stator current of the k+2th sampling period. k-2-n Stator direct axis reference voltage Until the k-2th sampling period T k-2 Stator direct axis reference voltage knth sampling period T k-n The actual stator direct axis current i d (kn) to the kth sampling period T k The actual stator direct axis current i d (k) is processed to obtain the k+1th sampling period T k+1 Stator direct axis predicted current i d (k+1), the delay compensation module performs the delay compensation on the kn-2th sampling period T k-2-n Stator quadrature axis reference voltage Until the k-2th sampling period T k-2 Stator quadrature axis reference voltage knth sampling period T k-n The actual stator quadrature axis current i q (kn) to the kth sampling period T k The actual stator quadrature axis current i q (k) is processed to obtain the k+1th sampling period T k+1 Stator quadrature axis predicted current i q (k+1);

[0164] Current regulator, the current regulator is used to design a stator direct axis current independent cost function is the stator direct axis reference current and the k+2th sampling period T k+2 Stator direct axis predicted current i d The square of the error between (k+2) Design stator quadrature-axis current cost function is the stator quadrature axis reference current and the k+2th sampling period T k+2 Stator quadrature axis predicted current i q The square of the error between (k+2)

[0165] And according to the set stator direct axis current independent cost function and the stator quadrature-axis current independent cost function The rectangular constraint space of the voltage vector in the αβ coordinate system is processed, and the influence of the four different regions in the rectangular constraint space on the d-axis and q-axis current responses is used to select the rectangular constraint space partition that makes the d-axis current change negatively toward the reference current and the q-axis current change negatively toward the reference current, and the output voltage vector is calculated to obtain the kth sampling period T k Stator direct axis reference voltage and the kth sampling period T k Stator quadrature axis reference voltage

[0166] The phase error module uses the minimum phase error method to apply the phase error to the kth sampling period T k Stator direct axis reference voltage and the kth sampling period T k Stator quadrature axis reference voltage Processing is performed to obtain the kth sampling period T k Actual voltage applied to stator direct axis u d (k) and the kth sampling period T k The actual applied voltage u of the stator quadrature axisq (k);

[0167] The second conversion module is used to convert the stator direct axis actual applied voltage u d (k) and the actual applied voltage u on the stator quadrature axis q (k) Perform coordinate changes to obtain the actual applied voltage u of the three-phase stator of the permanent magnet synchronous motor a (k) and u b (k) and u c (k) and transmitted to the inverter, a high dynamic response model-free predictive current control of the permanent magnet synchronous motor based on independent constraints is presented.

[0168] Since different K values ​​will affect the response time of the stator current of the PMSM drive system, resulting in different current dynamic response results, in order to select the appropriate K value in the dq axis current independent setting constraint, Matlab / Simul ink is used for simulation test. The parameters of the tested SMPMSM are shown in Table 3, where the dynamometer works in the speed mode and forms a pair-drag platform with the motor under test. The working conditions during the simulation test are: the d axis stator reference current is 0A, the q axis stator reference current initial value is 0A, and it steps to 26.7A at 3.5ms, and the dynamometer speed is set to 400rpm. K=0.02, 0.11, and 0.3 are selected for simulation.

[0169] Table 3 Nominal parameters of SMPMSM

[0170]

[0171] From the experimental results Figure 5 It can be seen that when K = 0.02, 0.11, and 0.3, the time required for the q-axis current response to enter the 5% error band is different. Larger and smaller k values ​​will slow down the q-axis dynamic response, so k = 0.11 is selected.

[0172] An inverter-powered surface-mounted permanent magnet synchronous motor (SMPMSM) experimental platform is established. The dynamometer is an asynchronous motor and uses dual closed-loop control of the speed loop and the current loop. The parameters of the tested SMPMSM are shown in Table 3. During the experimental test, the inverter dead time is 2.5μs, the inverter switching frequency is 10kHz, and the current loop control period is 100μs. The OS-MPC optimal solution model predictive control method and the experimental comparative study of the present invention are selected. Both OS-MPC and the present invention are based on the current super-local model, and the OS-MPC synthetic voltage vector method is a three-vector.

[0173] There are two experimental conditions:

[0174] First, the dynamic response change under high speed is tested. The DC bus voltage is set to 48V, the d-axis stator reference current is 0A, the q-axis stator reference current is initially 0A, and it is stepped to 26.7A at 3.5ms. The dynamometer speed is maintained at 400rpm. The experimental test results are as follows: Figure 6 and Figure 7 As shown;

[0175] from Figure 6 and Figure 7 It can be concluded that the time required for the q-axis dynamic response of the present invention to reach the 5% error band is shorter than that required for the q-axis dynamic response of OS-MPC to reach the 5% error band. The reason is that voltage saturation occurs in the dynamic process of OS-MPC, which slows down the speed of current tracking the reference value; the present invention uses dynamically changing The d-axis current in the dynamic process is modified to change in a negative direction, thereby improving the dynamic response speed of the q-axis current.

[0176] Secondly, the dynamic response change at low speed was tested. The DC bus voltage was set to 24V, the d-axis stator reference current was 0A, the q-axis stator reference current was initially 0A, and it was stepped to 20A in 3.5ms. The dynamometer speed was kept at 200rpm. The experimental test results are as follows: Figure 8 and Fig. 9 shown.

[0177] from Figure 8 and Fig. 9 It can be concluded that the time required for the q-axis dynamic response of the present invention to reach the 5% error band is shorter than that required for the q-axis dynamic response of OS-MPC to reach the 5% error band. The reason is that voltage saturation occurs in the dynamic process of OS-MPC, which slows down the speed of current tracking the reference value; the present invention uses dynamically changing The d-axis current in the dynamic process is modified to change in a negative direction, thereby improving the dynamic response speed of the q-axis current.

[0178] Comparing the dynamic responses of the present invention and OS-MPC at high and low speeds, it can be seen that the present invention achieves a significantly faster dynamic response speed.

[0179] In summary, in order to improve the current dynamic response speed under the voltage saturation state caused by insufficient voltage margin, the present invention derives the rectangular constraint space related to the dynamic response of the dq axis current in the αβ axis based on the super-local model of the PMSM drive system, analyzes and obtains the four dynamic change trends of the dq axis current corresponding to the reference voltage vector located in the four regions of the space, and gives the reference voltage vector selection basis that can improve the q axis stator current response speed under voltage saturation; constructs a cost function constraint generation scheme based on voltage feedback, which can adaptively obtain the d axis cost function constraint according to the voltage saturation degree, and combines the reference voltage vector selection basis, by making the d axis current change towards the reference current negatively, effectively increasing the q axis voltage margin, and realizing the PMSM drive system q axis stator current high dynamic and fast response. In addition, the proposed independent constraint high dynamic response model-free predictive current control method has the same dynamic and steady-state control structure, can realize the smooth switching between the system dynamic and steady-state control, and the system structure is simpler.

[0180] The above formulas are all dimensionless and numerical calculations. The formula is a formula for the most recent real situation obtained by collecting a large amount of data and performing software simulation. The preset parameters in the formula are set by technicians in this field according to actual conditions.

[0181] The above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination thereof. When implemented by software, the above embodiments may be implemented in whole or in part in the form of a computer program product. Those skilled in the art may appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein may be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed by hardware or software methods depends on the specific application and design constraints of the technical solution.

[0182] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, and may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0183] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application.

Claims

1. A high dynamic response model-free predictive current control method based on independent constraints, characterized in that: The specific steps include: Step 1: Set the sampling period of the PMSM drive system to T, and obtain the PMSM drive system at the kth sampling period T k The actual stator direct axis current i d (k), kth sampling period T k The actual stator quadrature axis current i q (k), kth sampling period T k The actual rotor position angle θ r (k) and the kth sampling period T k The DC power supply voltage u s (k), and due to the control timing delay applied to the kth control cycle T k Stator direct axis reference voltage Stator quadrature axis reference voltage Step 2: By obtaining the kth sampling period T k The stator direct axis estimate and the kth sampling period T k The stator quadrature axis estimator with disturbance Establish a super-local model of PMSM drive system; Step 3: Estimated stator direct axis values ​​of adjacent control cycles and stator quadrature axis estimate As a constant, in the kth sampling period T k To the k+1th sampling period T k+1 The first-order forward Euler method is used to discretize the PMSM drive system super-local model to obtain the k+1th sampling period T k+1 The predicted stator direct axis current i d (k+1) and the stator quadrature axis predicted current i q (k+1); Step 4: In the k+1th sampling period T k+1 To the k+2th sampling period T k+2 The first-order forward Euler method is used to discretize the PMSM drive system super-local model to obtain the k+2 sampling period T k+2 The predicted stator direct axis current i d (k+2) and the predicted stator quadrature axis current i q (k+2); Step 5: Design an independent cost function for stator direct-axis current related to current tracking error and the stator quadrature-axis current independent cost function According to the stator direct axis cost function and stator quadrature axis cost function Obtain the voltage vector rectangular constraint space; Step 6: According to the four regions of the voltage vector rectangular constraint space, the stator direct axis current i d (k) and stator quadrature axis current i q (k) Different effects of response, construct the cost function constraint of voltage feedback, select the reference voltage vector by obtaining the d-axis adaptive cost function constraint, and calculate the size of the output voltage vector to obtain the stator direct axis reference voltage of the voltage vector in the two-phase rotating coordinate system and stator quadrature axis reference voltage Step 7: Use the minimum phase error method to convert the stator direct axis reference voltage and stator quadrature axis reference voltage The amplitude is reduced to the inscribed circle of the voltage hexagon to obtain the actual applied voltage u on the stator direct axis d (k) and the actual applied voltage u on the stator quadrature axis q (k), the actual voltage u is applied to the stator direct axis d (k) and the actual applied voltage u on the stator quadrature axis q (k) Perform coordinate changes to obtain the actual applied voltage u of the three-phase stator of the permanent magnet synchronous motor a (k) and u b (k) and u c (k) Realize independent constraint-based high dynamic model-free predictive current control of permanent magnet synchronous motor; The stator direct axis reference voltage of the voltage vector in the two-phase rotating coordinate system is obtained and stator quadrature axis reference voltage The specific steps are: Step 6a: The voltage vector rectangular constraint space is divided into four regions i d ↓i q ↓、i d ↑i q ↓、i d ↓i q ↑andi d ↑i q ↑, has different effects on the dq axis current response, where i d ↑ indicates reference voltage Make the d-axis current change towards the reference current; i d ↓ indicates reference voltage Make the d-axis current change negatively toward the reference current; i q ↑ indicates reference voltage Make the q-axis current change towards the reference current; i q ↓ indicates reference voltage Make the q-axis current change towards the negative direction of the reference current; Step 6b: The size of will change the range of the voltage vector rectangular constraint space. Based on the principle of improving the high dynamic response speed of the stator current, the d-axis current changes negatively toward the reference current, increasing the q-axis voltage margin to avoid voltage saturation, and obtaining the dq-axis current independent setting constraints, as shown in the following formula: Where k is the d-axis feedback gain, The q-axis reference voltage generated by the current regulator, u q The actual applied voltage is obtained after the voltage saturation occurs on the q-axis; Step 6c: According to the d-axis current changing towards the reference current in the negative direction, that is, The rectangular constraint space converges to the straight line segment, and the reference voltage and The analytical expression of is obtained by using Park transformation Park variations are:

2. The high dynamic response model-free predictive current control method based on independent constraints according to claim 1, characterized in that: The actual stator direct axis current i d (k), actual stator quadrature axis current i q (k), actual rotor position angle θ r (k), DC power supply voltage u s (k) The specific steps of obtaining are: Step 1a: Use the current sensor to detect and obtain the kth sampling period T k The stator three-phase current a phase current i a (k) and the kth sampling period T k The b-phase current i b (k); Step 1b: Use the position sensor to detect and obtain the kth sampling period T k The actual rotor position angle θ r (k); Step 1c: Use the voltage sensor to detect and obtain the kth sampling period T k The DC power supply voltage u s (k); Step 1d: Use Clark's formula to calculate the phase a current i a (k), b-phase current i b (k) Perform equal amplitude transformation to obtain the kth sampling period T of the permanent magnet synchronous motor based on the two-phase stationary coordinate system k The actual stator α-axis current i α (k) and the kth sampling period T k The actual stator β-axis current i β (k), the transformation formula is; Wherein, k≥1 and k is a positive integer, k=1,2,3,….

3. The high dynamic response model-free predictive current control method based on independent constraints according to claim 1, characterized in that: The specific steps of establishing the PMSM drive system super-local model are as follows: define n as the data window length, and according to the kn-2th sampling period T k-2-n Stator direct axis reference voltage Until the k-2th sampling period T k-2 Stator direct axis reference voltage The kn-2th sampling period T k-2-n Stator quadrature axis reference voltage Until the k-2th sampling period T k-2 Stator quadrature axis reference voltage knth sampling period T k-n The actual stator direct axis current i d (kn) to the kth sampling period T k The actual stator direct axis current i d (k), knth sampling period T k-n The actual stator quadrature axis current i q (kn) to the kth sampling period T k The actual stator quadrature axis current i q (k), calculate and obtain the kth sampling period T k Estimated value of stator direct axis and the kth sampling period T k Estimated value of stator quadrature axis The stator direct axis estimated value and stator quadrature axis estimate The calculation formulas are: Where: m is the sampling point of the kth control cycle, α d is the stator direct axis voltage coefficient, α q is the stator quadrature axis voltage coefficient. When m―n≤0, let i d (kn) = 0, i q (kn) = 0, The calculation formula of the super-local model of the PMSM drive system is: Among them, i d is the stator direct axis current, i q is the stator quadrature axis current, α d is the stator direct axis voltage coefficient, α q is the stator quadrature-axis voltage coefficient.

4. The high dynamic response model-free predictive current control method based on independent constraints according to claim 1, characterized in that: In the kth sampling period T k To the k+1th sampling period T k+1 The specific formula for discretizing the hyperlocal model of the PMSM drive system using the first-order forward Euler method is: Among them, i d (k+1) k+1th sampling period T k+1 The predicted stator direct axis current at time i q (k+1) k+1th sampling period T k+1 The predicted stator quadrature axis current is The kth control period T k The actual voltage applied to the stator direct axis is, The kth control period T k The actual applied voltage on the stator quadrature axis, α d is the stator direct axis voltage coefficient, α q is the stator quadrature-axis voltage coefficient.

5. The high dynamic response model-free predictive current control method based on independent constraints according to claim 1, characterized in that: In the k+1th sampling period T k+1 To the k+2th sampling period T k+2 The calculation formula for discretizing the super-local model of the PMSM drive system using the first-order forward Euler method is: Among them, i d (k+2) k+2th sampling period T k+2 The predicted stator direct axis current at time i q (k+2) k+2th sampling period T k+2 The predicted stator quadrature axis current is The k+1th control period T k+1 The actual voltage applied to the stator direct axis is, The k+1th control period T k+1 The actual applied voltage on the stator quadrature axis, α d is the stator direct axis voltage coefficient, α q is the stator quadrature-axis voltage coefficient.

6. The high dynamic response model-free predictive current control method based on independent constraints according to claim 1, characterized in that: The design is related to the stator direct axis current independent cost function of the current tracking error and the stator quadrature-axis current independent cost function According to the stator direct axis cost function and stator quadrature axis cost function The specific steps to obtain the voltage vector rectangular constraint space are: Step 5a: Design independent cost function for stator direct-axis current Stator quadrature-axis current independent cost function The stator direct axis current independent cost function Stator quadrature-axis current independent cost function The mathematical formula is; in, is the stator direct axis reference current, is the stator quadrature axis reference current, i d (k+2) is the k+2th sampling period T k+2 Predicted stator direct axis current, i q (k+2) is the k+2th sampling period T k+2 Stator quadrature axis predicted current; Step 5b: According to the k+1th control period T k+1 The actual applied voltage on the stator direct axis and the k+1th control cycle T k+1 The actual applied voltage on the stator quadrature axis After Park transformation, and Transformed into a two-phase stationary coordinate system and The formula after Park transformation is: Step 5c: According to the two-phase stationary coordinate system and The current independent cost function is obtained, and the independent cost function is: Step 5d: Based on the stator direct axis reference current and the corresponding stator direct axis predicted current i d Three relationships of (k+2); greater than 0, equal to 0 and less than 0; stator quadrature axis reference current The corresponding stator quadrature axis predicted current i q Three relationships of (k+2): greater than 0, equal to 0, and less than 0; nine combinations are obtained, as described in the following formula: Step 5e: Substitute the independent cost functions into the stator direct axis reference current and the corresponding stator direct axis predicted current i d (k+2) relational formula, stator quadrature axis reference current The corresponding stator quadrature axis predicted current i q (k+2) relational formula: Step 5f: Using the inequality relationship of the following formula, the influence of different regions on the d-axis, q-axis and dq-axis currents in the αβ-axis two-phase rotating coordinate system space is obtained; Step 5g: According to the above equation, we can obtain and The corresponding straight line equation in the αβ axis is: in, k q =tanθ r , in accordance with The linear equation obtains four straight lines in the αβ axis two-phase rotating coordinate system space, forming a rectangular constraint space for the voltage vector. When different values ​​are taken, the range of the voltage vector rectangular constraint space will change.

7. A high dynamic response model-free predictive current control device based on independent constraints, characterized in that: The current control device is used to execute a high dynamic response model-free predictive current control method based on independent constraints according to any one of claims 1 to 6, comprising: The current sensor is used to detect and obtain the kth sampling period T k The stator three-phase current a phase current i a (k) and the kth sampling period T k The b-phase current i b (k); A voltage sensor is used to detect and obtain the kth sampling period T k DC power supply voltage u s (k); The position sensor is used to detect and obtain the kth sampling period T k The actual rotor position angle θ r (k); The first conversion module is used to convert the stator a phase current and i phase current provided by the current sensor. a (k) Stator b phase current i b (k) Using Clark coordinate transformation, the three-phase stationary coordinate system is converted into a two-phase stationary coordinate system to obtain the actual stator α-axis current i α (k) and the actual stator β-axis current i β (k), and the position sensor provides the actual rotor position angle θ r (k) Perform Park coordinate transformation to convert the two-phase stationary coordinate system into the two-phase rotating coordinate system to obtain the actual stator direct axis current i d (k) and the actual stator quadrature axis current i q (k); The delay compensation module generates the stator current of the k+2th sampling period by setting n as the data window length and the reference voltage of the k-2th sampling period. The delay compensation module generates the stator current of the k+2th sampling period by setting n as the data window length and the reference voltage of the k-2th sampling period and the stator current of the k+2th sampling period. k-2-n Stator direct axis reference voltage Until the k-2th sampling period T k-2 Stator direct axis reference voltage knth sampling period T k-n The actual stator direct axis current i d (kn) to the kth sampling period T k The actual stator direct axis current i d (k) is processed to obtain the k+1th sampling period T k+1 Stator direct axis predicted current i d (k+1), the delay compensation module performs the delay compensation on the kn-2th sampling period T k-2-n Stator quadrature axis reference voltage Until the k-2th sampling period T k-2 Stator quadrature axis reference voltage knth sampling period T k-n The actual stator quadrature axis current i q (kn) to the kth sampling period T k The actual stator quadrature axis current i q (k) is processed to obtain the k+1th sampling period T k+1 Stator quadrature axis predicted current i q (k+1); Current regulator, the current regulator is used to design a stator direct axis current independent cost function is the stator direct axis reference current and the k+2th sampling period T k+2 Stator direct axis predicted current i d The square of the error between (k+2) Design stator quadrature-axis current cost function is the stator quadrature axis reference current and the k+2th sampling period T k+2 Stator quadrature axis predicted current i q The square of the error between (k+2) And according to the set stator direct axis current independent cost function and the stator quadrature-axis current independent cost function Processing is performed to obtain the rectangular constraint space of the voltage vector in the αβ coordinate system. The influence of the four different regions in the rectangular constraint space on the d-axis and q-axis current responses is used to select the rectangular constraint space partition that makes the d-axis current change negatively toward the reference current and the q-axis current change negatively toward the reference current, and the output voltage vector is calculated to obtain the kth sampling period T k Stator direct axis reference voltage and the kth sampling period T k Stator quadrature axis reference voltage The phase error module uses the minimum phase error method to apply the phase error to the kth sampling period T k Stator direct axis reference voltage and the kth sampling period T k Stator quadrature axis reference voltage Processing is performed to obtain the kth sampling period T k Actual voltage applied to stator direct axis u d (k) and the kth sampling period T k The actual applied voltage u of the stator quadrature axis q (k); The second conversion module is used to convert the stator direct axis actual applied voltage u d (k) and the actual applied voltage u on the stator quadrature axis q (k) Perform coordinate changes to obtain the actual applied voltage u of the three-phase stator of the permanent magnet synchronous motor a (k) and u b (k) and u c (k) and transmitted to the inverter, a high dynamic response model-free predictive current control of the permanent magnet synchronous motor based on independent constraints is presented.

Images