Six-phase permanent magnet synchronous motor control method based on five-bridge-arm inverter

Abstract

The invention discloses a six-phase permanent magnet synchronous motor control method based on a five-bridge-arm inverter. The method comprises the following steps: performing preset matrix transformation on a natural coordinate system motor mathematical model of a six-phase permanent magnet synchronous motor to obtain a synchronous speed coordinate system motor mathematical model; determining a discrete prediction model according to the synchronous speed coordinate system motor mathematical model, and constructing a cost function according to the discrete prediction model; calculating the phase current when the five-bridge-arm inverter supplies power to the six-phase motor to determine a common bridge arm, and performing voltage vector synthesis on the voltage vector of the common bridge arm to obtain a target voltage vector; and calculating a required target voltage vector based on the discrete prediction model, a current reference value and the cost function, and outputting a corresponding basic voltage vector to control the six-phase permanent magnet synchronous motor. According to the method, multi-target optimization control and vector synthesis are realized through synchronous speed coordinate system modeling and a discrete prediction model, zero-sequence current and high-frequency harmonic waves are directly suppressed, and torque ripple is reduced.

Description

Technical Field

[0001] The present application relates to the technical field of motor control, and more specifically, to a control method for a six-phase permanent magnet synchronous motor based on a five-leg inverter. Background Art

[0002] Six-phase motors are usually driven by six-leg inverters. Due to their high reliability, low torque ripple, and high efficiency, they have wide attraction in the industrial field. It is of great significance to study six-phase inverter topologies with reduced switching devices, which can not only reduce costs, but also serve as a fault-tolerant solution for six-leg inverters to improve system reliability. The more common six-phase inverter topologies with reduced switching devices include nine-switch inverters, four-leg inverters, and five-leg inverters. Among them, the five-leg inverter is favored because it neither has the problem of capacitor overvoltage nor can be applied to fault-tolerant control.

[0003] In the existing methods for controlling a six-phase motor with a five-leg inverter, there are vector space decomposition control and double zero-sequence injection pulse width modulation control. Vector space decomposition control decomposes the six-phase current into two groups of orthogonal three-phase currents, and respectively adopts traditional three-phase vector control (VC). The torque and excitation components are independently adjusted by two groups of PI controllers, and the fifth leg is used for closed-loop compensation of the neutral point voltage drift; while the double zero-sequence injection PWM control injects double zero-sequence components into the six-phase current, combines space vector modulation (SVPWM) to optimize the voltage vector combination, and adjusts the amplitude of the zero-sequence current through a PI controller to suppress the third harmonic and neutral point imbalance, while realizing torque control.

[0004] However, in the prior art, when performing vector space decomposition control, the cooperation of multiple controllers is complex, the parameters are sensitive and the dynamic responses are asynchronous, which easily causes torque ripple, the computational resource occupancy rate is high, only the fundamental harmonic is suppressed, and the higher harmonics still exist, and the total harmonic distortion (THD) is relatively high. And the double zero-sequence injection PWM control needs to optimize multiple objectives such as torque, harmonic suppression, and neutral point voltage at the same time. The weight adjustment of the PI controller is difficult, the robustness is poor, the injection of high-frequency zero-sequence current significantly increases the IGBT switching loss, the efficiency is reduced, and it depends on accurate motor parameters (such as inductance, resistance), and parameter perturbation easily causes harmonic suppression failure. Summary of the Invention

[0005] In view of at least one defect or improvement requirement of the prior art, the present invention provides a control method for a six-phase permanent magnet synchronous motor based on a five-leg inverter, which is used to solve the problems in the prior art that the cooperation of multiple controllers is complex and the parameters are sensitive, resulting in asynchronous dynamic responses and torque ripple, while the harmonic suppression ability is limited, the computational resources are consumed highly, and the multi-objective optimization contradiction leads to poor robustness. The injection of high-frequency zero-sequence current causes additional losses, and it depends on accurate motor parameters and is easily affected by perturbation.

[0006] To achieve the above object, according to the first aspect of the present invention, a control method for a six-phase permanent magnet synchronous motor based on a five-leg inverter is provided, including:

[0007] Performing a preset matrix transformation on the motor mathematical model of the six-phase permanent magnet synchronous motor in the natural coordinate system to obtain the motor mathematical model in the synchronous speed coordinate system;

[0008] Determining a discrete prediction model according to the motor mathematical model in the synchronous speed coordinate system, and constructing a cost function according to the discrete prediction model;

[0009] Calculating the phase current when the five-leg inverter supplies power to the six-phase motor to determine the common bridge arm, and performing voltage vector synthesis on the voltage vector of the common bridge arm to obtain the target voltage vector;

[0010] Calculating the required target voltage vector based on the discrete prediction model, the current reference value and the cost function, and outputting the corresponding basic voltage vector to control the six-phase permanent magnet synchronous motor.

[0011] In a possible implementation manner, performing a preset matrix transformation on the motor mathematical model of the six-phase permanent magnet synchronous motor in the natural coordinate system to obtain the motor mathematical model in the synchronous speed coordinate system further includes:

[0012] Establishing the motor mathematical model of the six-phase permanent magnet synchronous motor in the natural coordinate system according to the motor mathematical model of the three-phase motor in the natural coordinate system;

[0013] Establishing a first transformation matrix and a second transformation matrix based on the motor mathematical model of the six-phase permanent magnet synchronous motor in the natural coordinate system;

[0014] Transforming the motor mathematical model in the natural coordinate system through the first transformation matrix and the second transformation matrix to obtain the motor mathematical model in the synchronous speed coordinate system.

[0015] In a possible implementation manner, determining a discrete prediction model according to the motor mathematical model in the synchronous speed coordinate system, and constructing a cost function according to the discrete prediction model further includes:

[0016] Performing discretization processing on the motor mathematical model in the synchronous speed coordinate system to obtain the discrete prediction model;

[0017] Constructing a cost function according to the motor reference parameters and the discrete prediction model.

[0018] In a possible implementation manner, the cost function is:

[0019]

[0020] where F cost is the cost function, i d , i q are the d-axis and q-axis currents respectively, i x , iy They are the x and y axis currents in the xy subspace respectively. k represents the kth sampling. The superscript "r" represents the reference value, the superscript "p" represents the predicted value, and λ is the weighting factor for the magnitude of the constrained harmonic space current i x ,i y .

[0021] In a possible implementation, when calculating the phase current of a five-leg inverter supplying power to a six-phase motor to determine the common leg, it further includes:

[0022] Calculating the phase current of the five-leg inverter supplying power to the six-phase motor according to the phase current amplitude and phase angle;

[0023] Calculating the corresponding common leg current for different common legs according to the phase current respectively;

[0024] Comparing the common leg current with the phase current amplitude to select the common leg.

[0025] In a possible implementation, when synthesizing voltage vectors of the common leg to obtain the target voltage vector, it further includes:

[0026] Calculating the corresponding voltage vectors respectively according to the leg switching states of the five-leg inverter;

[0027] Selecting the first voltage vectors that meet the preset requirements from the voltage vectors for vector synthesis to obtain the target voltage vector.

[0028] In a possible implementation, when selecting the first voltage vectors that meet the preset requirements from the voltage vectors for vector synthesis to obtain the target voltage vector, it further includes:

[0029] Selecting the first voltage vectors that meet the preset requirements according to the amplitude of the voltage vectors in the preset space;

[0030] Pairwise synthesizing the first voltage vectors with a preset phase difference through a vector synthesis method to obtain the target voltage vector.

[0031] According to the second aspect of the present invention, there is also provided a control device for a six-phase permanent magnet synchronous motor based on a five-leg inverter, including:

[0032] A mathematical model construction module configured to perform a preset matrix transformation on the natural coordinate system motor mathematical model of the six-phase permanent magnet synchronous motor to obtain the synchronous speed coordinate system motor mathematical model;

[0033] A cost function construction module configured to determine a discrete prediction model according to the synchronous speed coordinate system motor mathematical model and construct a cost function according to the discrete prediction model;

[0034] A vector synthesis module, which is configured to calculate the phase current when a five-leg inverter supplies power to a six-phase motor, determine a common leg, and perform voltage vector synthesis on the voltage vectors of the common leg to obtain a target voltage vector;

[0035] A motor control module, which is configured to calculate a required target voltage vector based on a discrete prediction model, a current reference value, and a cost function, and output a corresponding basic voltage vector to control a six-phase permanent magnet synchronous motor.

[0036] According to the third aspect of the present invention, there is also provided a six-phase permanent magnet synchronous motor control device based on a five-leg inverter, which includes at least one processing unit and at least one storage unit. Wherein, the storage unit stores a computer program, and when the computer program is executed by the processing unit, the processing unit is caused to execute the steps of the six-phase permanent magnet synchronous motor control method based on a five-leg inverter described in any one of the above.

[0037] According to the fourth aspect of the present invention, there is also provided a storage medium, which stores a computer program executable by an access authentication device. When the computer program runs on the access authentication device, the access authentication device is caused to execute the steps of the six-phase permanent magnet synchronous motor control method based on a five-leg inverter described in any one of the above.

[0038] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0039] A control method for a six-phase permanent magnet synchronous motor based on a five-leg inverter provided by the present invention reduces the number of switching devices through a common-leg design to save costs, and at the same time serves as an alternative for fault-tolerant control of a six-leg inverter. The predictive control based on the motor mathematical model directly generates the optimal voltage vector without relying on multiple PI controllers or complex parameter tuning, reduces the dependence on the accuracy of motor parameters (such as inductance and resistance), and improves the robustness under parameter perturbation. The nonlinear model in the natural coordinate system is converted into a linear model in the synchronous rotating coordinate system, which is convenient for accurately predicting future states (such as current and torque) and realizing real-time optimization of dynamic response. By constructing a cost function, the control input is rolled and optimized within the prediction time domain, directly suppressing torque ripple, improving the smoothness of the dynamic process, and transforming multi-objectives such as torque tracking, harmonic suppression, and loss minimization into a weighted single-objective optimization problem to avoid the trade-off contradiction in multi-objective optimization. For the power supply characteristics of the five-leg inverter, through the voltage vector synthesis technology of the common leg, the zero-sequence voltage component is flexibly adjusted to actively cancel harmonic currents and reduce the dependence on passive filters in traditional methods. Based on the explicit constraint ability of the discrete prediction model, the harmonic suppression target can be directly incorporated into the optimization process to avoid the limitations of traditional proportional-integral control for harmonic suppression. The predictive control predicts future states online based on the motor model, but has a low requirement for the accuracy of model parameters. Even in the presence of parameter perturbation, the control performance can still be maintained through feedback correction. Description of the Drawings

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0041] Figure 1 It is a schematic flowchart of an embodiment of the control method for a six-phase permanent magnet synchronous motor based on a five-leg inverter provided by the present invention;

[0042] Figure 2 Provided by the present invention Figure 1 It is a schematic flowchart of an embodiment of step S101 in

[0043] Figure 3 It is a schematic transformation diagram of an embodiment of the d-q coordinate transformation provided by the present invention;

[0044] Figure 4 It is a schematic flowchart of an embodiment of determining the common leg provided by the present invention;

[0045] Figure 5 It is a schematic structural diagram of an embodiment of a five-leg voltage source inverter provided by the present invention;

[0046] Figure 6 Schematic diagram of the distribution of voltage vectors when the BF common bridge arm is provided for the present invention;

[0047] Figure 7 Schematic diagram of the principle of vector synthesis provided for the present invention;

[0048] Figure 8 Vector diagram of an embodiment in which all vector syntheses provided for the present invention are completed;

[0049] Figure 9 Schematic diagram of the structure of an embodiment of a six-phase permanent magnet synchronous motor control device based on a five-bridge-arm inverter provided for the present invention;

[0050] Figure 10 Schematic diagram of the structure of a six-phase permanent magnet synchronous motor control device based on a five-bridge-arm inverter provided for an embodiment of the present invention. Detailed implementation manners

[0051] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0052] The terms "first", "second", "third", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products or devices.

[0053] Please refer to Figure 1 , Figure 1 Schematic diagram of the process of an embodiment of a six-phase permanent magnet synchronous motor control method based on a five-bridge-arm inverter provided for the present invention. In a specific embodiment of the present invention, a six-phase permanent magnet synchronous motor control method based on a five-bridge-arm inverter is disclosed, including:

[0054] S101. Perform a preset matrix transformation on the natural coordinate system motor mathematical model of the six-phase permanent magnet synchronous motor to obtain a synchronous speed coordinate system motor mathematical model;

[0055] S102. Determine the discrete prediction model according to the motor mathematical model in the synchronous speed coordinate system, and construct a cost function according to the discrete prediction model;

[0056] S103. Calculate the phase currents when the five-leg inverter supplies power to the six-phase motor to determine the common leg, and perform voltage vector synthesis on the voltage vectors of the common leg to obtain the target voltage vector;

[0057] S104. Calculate the required target voltage vector based on the discrete prediction model, the current reference value and the cost function, and output the corresponding basic voltage vector to control the six-phase permanent magnet synchronous motor.

[0058] In the above embodiment, the preset matrix transformation is the Clarke-Park double transformation, which realizes precise decoupling through the Clarke transformation (6-phase → 2-phase stationary coordinate system) and the Park transformation (stationary → rotating coordinate system). The Clarke transformation projects the six-phase current onto the orthogonal sub-plane (αβ). The Park transformation rotates the αβ coordinate system to the dq axis system synchronized with the rotor magnetic field, realizing the complete decoupling of the excitation (d-axis) and torque (q-axis) components of the stator current. It is necessary to obtain the rotor position information in real time (such as through an encoder or an observer) to ensure the synchronization of the coordinate transformation.

[0059] Under the influence of non-linear factors such as inductor saturation and temperature drift, online parameter identification is used to update the model parameters in real time to improve the prediction accuracy. It is necessary to not only predict the current at the next moment, but also evaluate the control effects in multiple future cycles to enhance the robustness of the system to time delay and sampling. Model predictive current control predicts the future current behavior by establishing a system model and uses the cost function to evaluate the effects of different control inputs. Its core lies in minimizing the cost function to achieve accurate current tracking. The cost function usually includes a current error term and a control constraint term, and the control action that minimizes the cost function is selected through online optimization, so as to achieve high-performance tracking of the reference current while satisfying the system constraints.

[0060] Carrier phase-shifted PWM or current hysteresis control is adopted to dynamically allocate the two-phase current demand and avoid local overheating. For example, when the B phase and the F phase share a common leg, the PWM duty cycle is adjusted by detecting the difference between the two-phase currents in real time to compensate for the current deviation. The number of output voltage vectors of the five-leg topology is reduced, and it is necessary to synthesize the target vector from the limited vectors through SVM or MPC. For example, the virtual vector technology is used to expand the feasible solution space, or the look-up table method is used to accelerate the online calculation. The current harmonics are reduced by optimizing the vector action sequence (such as the seven-segment SVM) to improve the motor efficiency.

[0061] Compared with the prior art, a six-phase permanent magnet synchronous motor control method based on a five-leg inverter provided by this embodiment reduces the number of switching devices through a common leg design to save costs, and at the same time serves as an alternative for the fault-tolerant control of a six-leg inverter. The predictive control based on the motor mathematical model directly generates the optimal voltage vector without relying on multiple PI controllers or complex parameter tuning, reduces the dependence on the accuracy of motor parameters (such as inductance and resistance), and improves the robustness under parameter perturbation. The nonlinear model in the natural coordinate system is converted into a linear model in the synchronous rotating coordinate system, which is convenient for accurately predicting future states (such as current and torque) and realizing real-time optimization of dynamic response. By constructing a cost function, the control input is optimized in a rolling manner within the prediction time domain, directly suppressing torque ripple, improving the smoothness of the dynamic process, and transforming multi-objectives such as torque tracking, harmonic suppression, and loss minimization into a weighted single-objective optimization problem to avoid the trade-off contradictions in multi-objective optimization. For the power supply characteristics of the five-leg inverter, through the voltage vector synthesis technology of the common leg, the zero-sequence voltage component is flexibly adjusted to actively cancel the harmonic current and reduce the dependence on passive filters in the traditional method. Based on the explicit constraint ability of the discrete prediction model, the harmonic suppression target can be directly incorporated into the optimization process to avoid the limitations of traditional proportional-integral control for harmonic suppression. Predictive control predicts future states online based on the motor model, but has a low requirement for the accuracy of model parameters. Even in the presence of parameter perturbation, the control performance can still be maintained through feedback correction.

[0062] Please refer to Figure 2 , Figure 2 an embodiment provided by the present invention Figure 1 is a schematic flowchart of an embodiment of step S101 in

[0063] S201. Establish the natural coordinate system mathematical model of the six-phase permanent magnet synchronous motor according to the natural coordinate system mathematical model of the three-phase motor;

[0064] S202. Establish a first transformation matrix and a second transformation matrix based on the natural coordinate system mathematical model of the six-phase permanent magnet synchronous motor;

[0065] S203. Transform the natural coordinate system mathematical model through the first transformation matrix and the second transformation matrix to obtain the synchronous speed coordinate system mathematical model.

[0066] In the above embodiment, the mathematical model of the six-phase permanent magnet synchronous motor in the natural coordinate system is similar to that of the three-phase motor, and its voltage equation and flux linkage equation are respectively expressed as:

[0067]

[0068] ψs = L s i s + λ s ψ p (2)

[0069] In the formula:

[0070] u s = [u A u B u C u D u E u F T ;

[0071] i s = [i A i B i C i D i E i F T ;

[0072] ψ s = [ψ A ψ B ψ C ψ D ψ E ψ F T ;

[0073] R s = R·E6;

[0074] λ s = [sinθsin(θ - 2π / 3)sin(θ - 4π / 3)sin(θ - π / 6)sin(θ - 5π / 6)sin(θ - 3π / 2)] T ;

[0075]

[0076] Among them, u s , i s , ψ s are the stator winding voltage, current, and magnetic flux respectively; R s is the stator winding resistance coefficient matrix (R is the stator resistance value, and E6 is the sixth-order identity matrix); λ s is the magnetic flux coefficient matrix, θ is the electrical angle, and its value is the angle between the rotor permanent magnet pole and the axis of phase A; L s is the stator inductance matrix, L XX (X = A, B, C, D, E, F) is the self-inductance of the stator six-phase winding, M XY ​​​(X, Y = A, B, C, D, E, F and X ≠ Y) is the mutual inductance of the stator six-phase winding, ψ p is the permanent magnet flux linkage.

[0077] The torque equation of the motor is:

[0078]

[0079] where T e is the electromagnetic torque, W m is the magnetic field energy storage, θ m is the mechanical angle, and P is the number of pole pairs.

[0080] The motion equation of the motor is:

[0081]

[0082] where J is the moment of inertia, ω m is the mechanical angular velocity, T L is the load torque, and B is the damping coefficient.

[0083] As can be seen from the above equations, there are coupling relationships among the parameters of the six-phase motor. To simplify the model and control algorithm, the order of the equations can be reduced and decoupling can be achieved by establishing a synchronous speed coordinate system.

[0084] Please refer to Figure 3 , Figure 3 , which is the transformation schematic diagram of an embodiment of the d-q coordinate transformation provided by the present invention. The mathematical model of the six-phase permanent magnet synchronous motor can be represented in the synchronous speed coordinate system. The stator and rotor windings are transformed from the natural coordinate system to the synchronous speed coordinate system by using the Clarke-Park transformation matrix.

[0085] The Clarke transformation matrix (the first transformation matrix) of the six-phase permanent magnet synchronous motor is:

[0086]

[0087] The coefficient k = 1 / 3 of is determined based on the constant amplitude principle. If the constant power principle is adopted, the corresponding coefficients

[0088] The first two rows of Figure 3 correspond to the α-β subspace and participate in the electromechanical energy conversion. Therefore, only these two rows are subjected to coordinate transformation.

[0089]

[0090] where E4 is a fourth-order identity matrix.

[0091] Multiplying Equation (5) by Equation (6), the Clarke-Park transformation matrix of the six-phase permanent magnet synchronous motor can be obtained as follows:

[0092]

[0093] Multiplying Equation (1) and Equation (2) by Equation (7) respectively, the voltage and flux linkage equations of the motor in the synchronous speed coordinate system can be obtained as follows:

[0094]

[0095] where, ω e is the electrical angular velocity, u d , u q are the d-axis and q-axis voltages respectively, u x , u y are the x-axis voltage and y-axis voltage in the xy space respectively, i d , i q are the d-axis and q-axis currents respectively, i x , i y are the x-axis current and y-axis current in the xy space respectively, ψ d , ψ q are the d-axis and q-axis flux linkages respectively, ψ x , ψ y are the x-axis flux linkage and y-axis flux linkage in the xy space respectively, L d , L q are the direct-axis inductance and quadrature-axis inductance respectively, L ls is the leakage inductance.

[0096] Multiplying Equation (3) by Equation (7), the torque equation of the motor in the synchronous speed coordinate system can be obtained as follows:

[0097] T e = 3P(i q ψ d - i d ψ q ) = 3Pi q [ψ p +(L d - L q )i d (10)

[0098] where, T s is the discrete time, k and k + 1 represent the kth sampling and the (k + 1)th sampling respectively.

[0099] In some embodiments of the present invention, determining a discrete prediction model according to the mathematical model of the synchronous speed coordinate system motor, and constructing a cost function according to the discrete prediction model, further includes:

[0100] The mathematical model of the motor in the synchronous speed coordinate system is discretized to obtain a discrete prediction model;

[0101] A cost function is constructed according to the reference parameters of the motor and the discrete prediction model.

[0102] In the above embodiment, in the finite set model predictive control, the motor model is used to predict the future state of the system under different voltage control sets, and the prediction results are evaluated through the cost function, so as to select the optimal control set for output (that is, the scheme with the minimum cost function).

[0103] Generally, the forward Euler method is used to discretize equations (8) and (9) to construct a discrete prediction model:

[0104]

[0105] In some embodiments of the present invention, the cost function is:

[0106]

[0107] Where F cost is the cost function, i x , i y are the x and y axis currents in the xy subspace respectively, k represents the kth sampling, the superscript "r" represents the reference value, the superscript "p" represents the predicted value, and λ is the weight factor for restricting the magnitudes of the harmonic space currents i x , i y .

[0108] Please refer to Figure 4 , Figure 4 which is a schematic flow chart of an embodiment for determining the common bridge arm provided by the present invention. In some embodiments of the present invention, when calculating the phase current when the five-bridge-arm inverter supplies power to the six-phase motor to determine the common bridge arm, it further includes:

[0109] S401. Calculate the phase current when the five-bridge-arm inverter supplies power to the six-phase motor according to the phase current amplitude and phase angle;

[0110] S402. Calculate the corresponding common bridge arm current for different common bridge arms according to the phase current respectively;

[0111] S403. Compare the common bridge arm current with the phase current amplitude to select the common bridge arm.

[0112] As a preferred embodiment, the present invention is described by taking phase F as an example. Please refer to Figure 5 , Figure 5Schematic diagram of a structure of an embodiment of the five-leg voltage source inverter provided by the present invention. When a five-leg inverter supplies power to a six-phase motor, there are three different operating modes: the AF common leg, the BF common leg, and the CF common leg.

[0113] Two phases sharing the same leg will cause an increase in the current of the common leg. Therefore, it is necessary to analyze its current. When the asymmetric six-phase motor is operating normally, the phase currents are:

[0114]

[0115] Among them, I m is the phase current amplitude, and θ A is the phase angle of the A-phase current.

[0116] AF common leg:

[0117] i COM = i A + i F = I m cosθ A + I m cos(θ A + π / 2) = 1.414I m cos(θ A + 45°) (15)

[0118] Among them, i COM is the current of the common leg.

[0119] BF common leg:

[0120] i COM = i B + i F = I m cos(θ A - 2π / 3) + I m cos(θ A + π / 2) = 0.517I m cos(θ A + 165°) (16)

[0121] CF common leg:

[0122] i COM = i C + i F = I m cos(θ A + 2π / 3) + I m cos(θ A + π / 2) = 1.932I m cos(θ A(17)(+105°)

[0123] It is not difficult to find that there is no overcurrent problem when the BF common bridge arm is used, and the rated current of the common bridge arm is only 0.517 times that of the normal bridge arm current (less than I m ), while in the other two cases, the rated current of the common bridge arm exceeds the normal bridge arm current (greater than I m ). Therefore, the BF common bridge arm operation mode is selected. Similarly, when other phases (phases other than B and F) fail, the CD common bridge arm mode or the AE common bridge arm mode can be selected.

[0124] Please refer to Figure 6 , Figure 6 , which is a schematic diagram of the distribution of voltage vectors when the BF common bridge arm is provided by the present invention. In some embodiments of the present invention, the voltage vectors of the common bridge arm are synthesized to obtain the target voltage vector, and it further includes:

[0125] Calculating the corresponding voltage vectors according to the bridge arm switch states of the five-bridge-arm inverter;

[0126] Screening out the first voltage vectors that meet the preset requirements from the voltage vectors for vector synthesis to obtain the target voltage vector.

[0127] In the above embodiment, a two-level five-bridge-arm voltage source inverter is used to supply power to a six-phase motor, and its topological structure is as Figure 5 shown. Each bridge arm of this inverter has two switch states, S X =1 (X = A, B, C, D, E, F) represents that the upper tube is turned on and the lower tube is turned off, and S X =0 is the opposite. Each switch state corresponds to a specific voltage vector:

[0128]

[0129] It should be noted that the S values of the two phases of the common bridge arm are the same, so a total of 2 5 = 32 switch states can be generated. Specifically, when the BF shares the same bridge arm, S B = S F Substituting into equations (18) and (19) can obtain the corresponding voltage vectors as Figure 6 shown.

[0130] In some embodiments of the present invention, screening out the first voltage vectors that meet the preset requirements from the voltage vectors for vector synthesis to obtain the target voltage vector further includes:

[0131] Screening out the first voltage vectors that meet the preset requirements according to the amplitude of the voltage vectors in the preset space;

[0132] The first voltage vectors with a preset phase difference are combined pairwise into target voltage vectors through a vector synthesis method.

[0133] In the above embodiments, as Figure 6 shown, for the convenience of analysis, similar to the case of a six-bridge arm, the 30 non-zero vectors are divided into 4 groups according to the magnitude of the voltage vectors in the α-β subspace from large to small: large vectors L4, medium vectors L3, basic vectors L2, and small vectors L1. The large vectors L4 in the α-β subspace have the smallest magnitude in the x-y subspace, while the small vectors L1 have the largest magnitude in the x-y subspace. The magnitudes of the medium vectors L3 and the basic vectors L2 remain unchanged. In a six-bridge arm inverter, the common practice is to select 12 large vectors L4 as the voltage control set, which can ensure a high utilization rate of the DC bus voltage and a low harmonic content.

[0134] It should be noted that in the embodiments of the present invention, the basic vectors are twelve basic voltage vectors decomposed from a six-phase voltage system in a specific coordinate system (such as the α-β or d-q coordinate system), corresponding to the combination of the inverter switch states.

[0135] However, as Figure 6 can be seen, when the BF common bridge arm is used, only 2 large vectors L4 remain in the α-β subspace and cannot be directly used as the control set. At the same time, it is observed that all the basic vectors L2 in the α-β subspace exist when the BF common bridge arm is used. Therefore, a vector synthesis method is adopted, and two adjacent basic vectors L2 with a phase difference of 30° are used to synthesize the large vector L4.

[0136] Please refer to Figure 7 , Figure 7 which is a schematic diagram of the principle of an embodiment of vector synthesis provided by the present invention. Taking the synthesis of the large vector 64 from the basic vectors 04 and 67 as an example, the vector synthesis diagram is as Figure 7 shown.

[0137] Please refer to Figure 8 , Figure 8 which is a vector diagram of an embodiment of the completion of all vector syntheses provided by the present invention. Originally, one large vector was implemented in each period T s is replaced by implementing two basic vectors in each period, and the action times of the two basic vectors are Therefore, the synthesized vector has the same direction as the known large vector but half of its magnitude. Finally, the projections of all the synthesized vectors in the α-β subspace are as Figure 8 shown.

[0138] In view of the above relationship between the synthesized vector and the large vector, in specific implementations, for the sake of simplifying the process, the cost function F cost can directly substitute to find the optimal control voltage set, and the corresponding two basic vectors are output during output.

[0139] To better implement the six-phase permanent magnet synchronous motor control method based on a five-bridge-arm inverter in the embodiments of the present invention, based on the six-phase permanent magnet synchronous motor control method based on a five-bridge-arm inverter, correspondingly, please refer to Figure 9 , Figure 9 FIG. is a schematic structural diagram of an embodiment of a six-phase permanent magnet synchronous motor control device based on a five-bridge-arm inverter provided by the present invention. The embodiments of the present invention provide a six-phase permanent magnet synchronous motor control device 900 based on a five-bridge-arm inverter, including:

[0140] A mathematical model construction module 910, configured to perform a preset matrix transformation on the motor mathematical model in the natural coordinate system of the six-phase permanent magnet synchronous motor to obtain a motor mathematical model in the synchronous speed coordinate system;

[0141] A cost function construction module 920, configured to determine a discrete prediction model according to the motor mathematical model in the synchronous speed coordinate system, and construct a cost function according to the discrete prediction model;

[0142] A vector synthesis module 930, configured to calculate the phase current when the five-bridge-arm inverter supplies power to the six-phase motor to determine the common bridge arm, and perform voltage vector synthesis on the voltage vectors of the common bridge arm to obtain a target voltage vector;

[0143] A motor control module 940, configured to calculate the required target voltage vector based on the discrete prediction model, the current reference value, and the cost function, and output the corresponding basic voltage vector to control the six-phase permanent magnet synchronous motor.

[0144] It should be noted here that: The device 900 provided in the above embodiment can implement the technical solutions described in the above method embodiments. The specific implementation principles of the above modules or units can be referred to the corresponding content in the above method embodiments, and will not be elaborated here.

[0145] Please refer to Figure 10 , Figure 10 FIG. is a schematic structural diagram of a six-phase permanent magnet synchronous motor control device based on a five-bridge-arm inverter provided by an embodiment of the present invention. Based on the above six-phase permanent magnet synchronous motor control method based on a five-bridge-arm inverter, the present invention also correspondingly provides a six-phase permanent magnet synchronous motor control device based on a five-bridge-arm inverter. The six-phase permanent magnet synchronous motor control device based on a five-bridge-arm inverter can be a computing device such as a mobile terminal, a desktop computer, a notebook, a palm computer, and a server. The six-phase permanent magnet synchronous motor control device 1000 based on a five-bridge-arm inverter includes a processor 1010, a memory 1020, and a display 1030. Figure 10Only some components of the six-phase permanent magnet synchronous motor control device based on a five-bridge-arm inverter are shown, but it should be understood that it is not necessary to implement all the shown components, and more or fewer components can be alternatively implemented.

[0146] The memory 1020 may be an internal storage unit of the six-phase permanent magnet synchronous motor control device 1000 based on a five-bridge-arm inverter in some embodiments, such as a hard disk or memory of the six-phase permanent magnet synchronous motor control device 1000 based on a five-bridge-arm inverter. The memory 1020 may also be an external storage device of the six-phase permanent magnet synchronous motor control device 1000 in other embodiments, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. equipped on the six-phase permanent magnet synchronous motor control device 1000 based on a five-bridge-arm inverter. Further, the memory 1020 may include both an internal storage unit of the six-phase permanent magnet synchronous motor control device 1000 and an external storage device. The memory 1020 is used to store application software installed on the six-phase permanent magnet synchronous motor control device 1000 based on a five-bridge-arm inverter and various types of data, such as program codes installed on the six-phase permanent magnet synchronous motor control device 1000 based on a five-bridge-arm inverter. The memory 1020 may also be used to temporarily store data that has been output or will be output. In one embodiment, a six-phase permanent magnet synchronous motor control program 1040 based on a five-bridge-arm inverter is stored on the memory 1020, and the six-phase permanent magnet synchronous motor control program 1040 based on a five-bridge-arm inverter can be executed by the processor 1010, thereby implementing the six-phase permanent magnet synchronous motor control method according to the embodiments of the present application.

[0147] The processor 1010 may be a Central Processing Unit (CPU), a microprocessor or other data processing chips in some embodiments, and is used to run the program codes stored in the memory 1020 or process data, such as executing the six-phase permanent magnet synchronous motor control method based on a five-bridge-arm inverter, etc.

[0148] The display 1030 may be an LED display, a liquid crystal display, a touch liquid crystal display, and an OLED (Organic Light-Emitting Diode) toucher, etc. in some embodiments. The display 1030 is used to display information on the six-phase permanent magnet synchronous motor control device 1000 based on a five-bridge-arm inverter and to display a visual user interface. The components 1010 - 1030 of the six-phase permanent magnet synchronous motor control device 1000 communicate with each other through a system bus.

[0149] In one embodiment, when the processor 1010 executes the six-phase permanent magnet synchronous motor control program 1040 based on a five-bridge-arm inverter in the memory 1020, the steps in the above-described six-phase permanent magnet synchronous motor control method based on a five-bridge-arm inverter are implemented.

[0150] This embodiment also provides a computer-readable storage medium, on which a six-phase permanent magnet synchronous motor control program based on a five-bridge-arm inverter is stored. When the six-phase permanent magnet synchronous motor control program based on a five-bridge-arm inverter is executed by a processor, the following steps are implemented:

[0151] Perform a preset matrix transformation on the natural coordinate system motor mathematical model of the six-phase permanent magnet synchronous motor to obtain a synchronous speed coordinate system motor mathematical model;

[0152] Determine a discrete prediction model according to the synchronous speed coordinate system motor mathematical model, and construct a cost function according to the discrete prediction model;

[0153] Calculate the phase current when the five-bridge-arm inverter supplies power to the six-phase motor to determine the common bridge arm, and perform voltage vector synthesis on the voltage vector of the common bridge arm to obtain a target voltage vector;

[0154] Calculate the required target voltage vector based on the discrete prediction model, the current reference value, and the cost function, and output the corresponding basic voltage vector to control the six-phase permanent magnet synchronous motor.

[0155] In summary, the six-phase permanent magnet synchronous motor control method based on a five-leg inverter provided by the present invention reduces the number of switching devices through the common-leg design, saving costs, and at the same time serves as an alternative for the fault-tolerant control of a six-leg inverter. The predictive control based on the motor mathematical model directly generates the optimal voltage vector, without relying on multiple PI controllers or complex parameter tuning, reducing the dependence on the accuracy of motor parameters (such as inductance and resistance), and enhancing the robustness under parameter perturbation. The nonlinear model in the natural coordinate system is converted into a linear model in the synchronous rotating coordinate system, facilitating the accurate prediction of future states (such as current and torque), and realizing the real-time optimization of dynamic response. By constructing a cost function, the control input is optimized in a rolling manner within the prediction time domain, directly suppressing torque ripple, improving the smoothness of the dynamic process, and transforming multi-objectives such as torque tracking, harmonic suppression, and loss minimization into a weighted single-objective optimization problem, avoiding the trade-off contradictions in multi-objective optimization. For the power supply characteristics of the five-leg inverter, through the voltage vector synthesis technology of the common leg, the zero-sequence voltage component is flexibly adjusted to actively cancel harmonic currents, reducing the dependence on passive filters in traditional methods. Based on the explicit constraint ability of the discrete prediction model, the harmonic suppression target can be directly incorporated into the optimization process, avoiding the limitations of traditional proportional-integral control for harmonic suppression. Predictive control predicts future states online based on the motor model, but has a low requirement for the accuracy of model parameters. Even in the presence of parameter perturbation, the control performance can still be maintained through feedback correction.

[0156] This application also provides a computer-readable storage medium, on which a computer program is stored. When the program is executed by a processor, the steps of the above method are implemented. Among them, the computer-readable storage medium may include, but is not limited to, any type of disk, including floppy disks, optical disks, DVDs, CD-ROMs, microdrives, and magneto-optical disks, ROM, RAM, EPROM, EEPROM, DRAM, VRAM, flash memory devices, magnetic cards or optical cards, nanosystems (including molecular memory ICs), or any type of medium or device suitable for storing instructions and / or data.

[0157] It should be noted that for the foregoing method embodiments, for the sake of simple description, they are all expressed as a series of action combinations. However, those skilled in the art should know that this application is not limited by the described action sequence, because according to this application, certain steps can be performed in other sequences or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to this application.

[0158] In the above embodiments, the descriptions of the various embodiments have their own emphases. For the parts not detailed in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0159] In several embodiments provided in this application, it should be understood that the disclosed device can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed coupling or direct coupling or communication connection between each other can be through some service interfaces. The indirect coupling or communication connection of the device or unit can be in electrical or other forms.

[0160] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0161] In addition, in each embodiment of this application, the functional units can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0162] If the above integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of this application. And the aforementioned memory includes: USB flash drives, read-only memories (ROM), random access memories (RAM), mobile hard disks, magnetic disks, or optical discs and other media that can store program codes.

[0163] Those of ordinary skill in the art can understand that all or part of the steps in the various methods of the above embodiments can be completed by instructing relevant hardware through a program. This program can be stored in a computer-readable memory. The memory can include: flash drives, read-only memories (ROM), random access memories (RAM), magnetic disks, or optical discs, etc.

[0164] The above are only exemplary embodiments of the present disclosure, and the scope of the present disclosure cannot be limited thereby. That is, any equivalent changes and modifications made in accordance with the teachings of the present disclosure still fall within the scope covered by the present disclosure. Those skilled in the art will readily conceive of other embodiments of the present disclosure after considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common general knowledge or conventional technical means in the technical field not recorded in the present disclosure. The specification and examples are only regarded as exemplary, and the scope and spirit of the present disclosure are defined by the claims.

[0165] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0166] It is easy for those skilled in the art to understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A six-phase permanent magnet synchronous motor control method based on a five-leg inverter, characterized in that: include: Performing a preset matrix transformation on the natural coordinate system motor mathematical model of the six-phase permanent magnet synchronous motor to obtain the synchronous speed coordinate system motor mathematical model; Determine a discrete prediction model according to the synchronous speed coordinate system motor mathematical model, and construct a cost function according to the discrete prediction model; The phase current when the five-bridge-arm inverter supplies power to the six-phase motor is calculated to determine the common bridge arm, and the voltage vector of the common bridge arm is synthesized to obtain the target voltage vector; The required target voltage vector is calculated based on the discrete prediction model, the current reference value and the cost function, and the corresponding basic voltage vector is output to control the six-phase permanent magnet synchronous motor.

2. The six-phase permanent magnet synchronous motor control method based on the five-leg inverter according to claim 1, characterized in that: The method of performing a preset matrix transformation on the natural coordinate system motor mathematical model of the six-phase permanent magnet synchronous motor to obtain the synchronous speed coordinate system motor mathematical model also includes: The natural coordinate coefficient mathematical model of the six-phase permanent magnet synchronous motor is established according to the natural coordinate coefficient mathematical model of the three-phase motor; A first transformation matrix and a second transformation matrix are established based on a natural coordinate system motor mathematical model of a six-phase permanent magnet synchronous motor; The natural coordinate system motor mathematical model is transformed by the first transformation matrix and the second transformation matrix to obtain the synchronous speed coordinate system motor mathematical model.

3. The six-phase permanent magnet synchronous motor control method based on the five-leg inverter according to claim 1, characterized in that: The method of determining a discrete prediction model according to the synchronous speed coordinate system motor mathematical model and constructing a cost function according to the discrete prediction model also includes: Discretizing the synchronous speed coordinate system motor mathematical model to obtain a discrete prediction model; A cost function is constructed according to the motor reference parameters and the discrete prediction model.

4. The six-phase permanent magnet synchronous motor control method based on the five-leg inverter according to claim 1, characterized in that: The cost function is: Among them, F cost is the cost function, i d ,i q , respectively, d and q axis currents, i x ,i y are the x-axis and y-axis currents of the xy subspace, respectively. k represents the kth sampling. The "r" superscript represents the reference value, the "p" superscript represents the predicted value, and λ is the constrained harmonic space current i x ,i y Weighting factor for size.

5. The six-phase permanent magnet synchronous motor control method based on the five-leg inverter according to claim 1, characterized in that: The method of calculating the phase current when the five-bridge-arm inverter supplies power to the six-phase motor to determine the shared bridge arm also includes: Calculate the phase current when the five-leg inverter supplies power to the six-phase motor according to the phase current amplitude and phase angle; Calculating the common bridge arm currents corresponding to different common bridge arms according to the phase currents; The common bridge arm is selected based on the comparison between the common bridge arm current and the phase current amplitude.

6. The six-phase permanent magnet synchronous motor control method based on the five-leg inverter according to claim 1, characterized in that: The step of synthesizing the voltage vector of the common bridge arm to obtain the target voltage vector further includes: Calculate the corresponding voltage vectors according to the switch states of the bridge arms of the five-bridge-arm inverter; A first voltage vector that meets preset requirements is selected from the voltage vectors for vector synthesis to obtain a target voltage vector.

7. The six-phase permanent magnet synchronous motor control method based on the five-leg inverter according to claim 6, characterized in that: The step of selecting a first voltage vector that meets a preset requirement from the voltage vectors and performing vector synthesis to obtain a target voltage vector also includes: Filtering out a first voltage vector that meets preset requirements according to the amplitude of the voltage vector in a preset space; The first voltage vectors with a preset angle difference are synthesized in pairs into a target voltage vector by a vector synthesis method.

8. A six-phase permanent magnet synchronous motor control device based on a five-leg inverter, characterized in that: include: A mathematical model building module, which is configured to perform a preset matrix transformation on the natural coordinate system motor mathematical model of the six-phase permanent magnet synchronous motor to obtain a synchronous speed coordinate system motor mathematical model; A cost function construction module, configured to determine a discrete prediction model according to the synchronous speed coordinate system motor mathematical model, and construct a cost function according to the discrete prediction model; A vector synthesis module is configured to calculate the phase current when the five-bridge-arm inverter supplies power to the six-phase motor to determine the common bridge arm, and perform voltage vector synthesis on the voltage vector of the common bridge arm to obtain a target voltage vector; The motor control module is configured to calculate the required target voltage vector based on the discrete prediction model, the current reference value and the cost function, and output the corresponding basic voltage vector to control the six-phase permanent magnet synchronous motor.

9. A six-phase permanent magnet synchronous motor control device based on a five-leg inverter, characterized in that: It includes at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, and when the computer program is executed by the processing unit, the processing unit executes the steps of the six-phase permanent magnet synchronous motor control method based on the five-leg inverter according to any one of claims 1 to 7.

10. A storage medium, characterized in that: It stores a computer program executable by an access authentication device. When the computer program runs on the access authentication device, the access authentication device executes the steps of the six-phase permanent magnet synchronous motor control method based on a five-leg inverter as described in any one of claims 1 to 7.

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