Method, device, equipment and program product for determining switching state of rectifier

Abstract

The present disclosure relates to the technical field of rectifiers, and in particular, to a method, apparatus, device and program product for determining a switching state of a rectifier. The method for determining the switching state of the rectifier comprises: determining a standard voltage vector of the rectifier, wherein the rectifier outputs a reference voltage under the standard voltage vector; determining a standard point corresponding to the standard voltage vector in a three-phase coordinate system; determining a preset point set corresponding to voltage vectors of all switching states of the rectifier in the three-phase coordinate system, and determining a candidate point set with a distance less than a first distance from the standard point from the preset point set; and determining a target voltage vector for adjusting the switching state of the rectifier from the candidate point set.

Description

Technical Field

[0001] This disclosure relates to the field of rectifier technology, and in particular to a method, apparatus, device, and program product for determining the switching state of a rectifier. Background Technology

[0002] Rectifiers have multiple switching states; for example, a three-level neutral point-clamped (NPC) rectifier has 27 switching states.

[0003] When adjusting the switching states of a rectifier, related technologies typically require iterating through and calculating the voltage vectors corresponding to all switching states of the rectifier within each control cycle to determine the target voltage vector. However, this method involves a large amount of computation and is difficult to operate in real-time within short control cycles (e.g., 100 microseconds), limiting the application of three-level NPC rectifiers in high-performance scenarios. Summary of the Invention

[0004] To overcome the problems existing in the related technologies, this disclosure provides a method, apparatus, equipment and program product for determining the switching state of a rectifier, which can solve the above problems.

[0005] According to a first aspect of the present disclosure, a method for determining the switching state of a rectifier is provided. The method includes: determining a standard voltage vector of the rectifier, wherein the output voltage of the rectifier under the standard voltage vector is a reference voltage; determining a standard point corresponding to the standard voltage vector in a three-phase coordinate system; determining a preset set of voltage vectors corresponding to all switching states of the rectifier in the three-phase coordinate system, and determining a set of candidate points from the preset set of points whose distance from the standard point is less than a first distance; and determining a target voltage vector from the candidate point set for adjusting the switching state of the rectifier.

[0006] According to a second aspect of the present disclosure, an apparatus for determining the switching state of a rectifier is provided. The apparatus includes: a first processing unit configured to determine a standard voltage vector of the rectifier, wherein the output voltage of the rectifier under the standard voltage vector is a reference voltage; a second processing unit configured to determine a standard point corresponding to the standard voltage vector in a three-phase coordinate system; determine a preset set of voltage vectors corresponding to all switching states of the rectifier in the three-phase coordinate system, and determine a set of candidate points from the preset set of points whose distance from the standard point is less than a first distance; and a third processing unit configured to determine a target voltage vector from the set of candidate points for adjusting the switching state of the rectifier.

[0007] According to a third aspect of the present disclosure, an electronic device is provided, comprising: a processor and a memory; the memory being used to store a computer program; and the processor being used to execute, by invoking the computer program, a method for determining the switching state of a rectifier as described in the first aspect.

[0008] According to a fourth aspect of the present disclosure, a computer program product is provided, including a computer program that, when executed by a processor, implements the method as described in the first aspect.

[0009] The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects: This disclosure, after determining the standard voltage vector, transforms the standard voltage vector and the voltage vectors corresponding to all switching states into a three-phase coordinate system. Then, based on the distance between the standard point and a preset point set, a candidate point set is determined, and the target voltage vector is determined from the candidate point set. This disclosure does not perform traversal calculations on all voltage vectors; instead, it first determines the candidate point set from the preset point set, reducing the number of candidate voltage vectors that need to be calculated. The target voltage vector is then determined from these candidate voltage vectors, thereby improving efficiency and real-time performance.

[0010] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0011] The accompanying drawings, which are incorporated in and form part of this disclosure, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0012] Figure 1 This is a schematic flowchart illustrating a method for determining the switching state of a rectifier according to an exemplary embodiment of the present disclosure.

[0013] Figure 2 This is a schematic flowchart illustrating a control method for a rectifier according to an exemplary embodiment of the present disclosure.

[0014] Figure 3 This disclosure is a block diagram illustrating a device for determining the switching state of a rectifier according to an exemplary embodiment.

[0015] Figure 4 This is a schematic diagram of the structure of a computer device according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0016] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this disclosure as detailed in the appended claims.

[0017] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0018] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various information, such information should not be limited to these terms. These terms are used only to distinguish information of the same type from one another. For example, without departing from the scope of this disclosure, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination."

[0019] Traditional three-level NPC (Neutral Point Camped) rectifiers have 27 switching states. In one control cycle, all switching states need to be traversed before the target switching state is selected to control the rectifier.

[0020] It is evident that when a rectifier has multiple switching states, the relevant technologies use a traversal approach to determine the target switching state. This approach involves a large amount of computation and limits the control cycle.

[0021] To address the aforementioned technical problems, this disclosure proposes a method for determining the switching state of a rectifier.

[0022] Figure 1 This is a schematic flowchart illustrating a method for determining the switching state of a rectifier according to an embodiment of the present disclosure. The method for determining the switching state of a rectifier can be used to determine the switching state of the rectifier. After determining the switching state, the switching state can be controlled by the corresponding voltage vector, thereby controlling the output voltage of the rectifier.

[0023] In some embodiments, the rectifier may include a three-level NPC rectifier.

[0024] like Figure 1As shown, the methods for determining the switching state of the rectifier include: In step S201, a standard voltage vector of the rectifier is determined, wherein the output voltage of the rectifier under the standard voltage vector is a reference voltage; In step S202, the standard point corresponding to the standard voltage vector in the three-phase coordinate system is determined; In step S203, a preset set of points in the three-phase coordinate system is determined for the voltage vectors corresponding to all switching states of the rectifier, and a set of candidate points whose distance from the standard point is less than a first distance is determined from the preset set of points. In step S204, a target voltage vector for adjusting the switching state of the rectifier is determined from the candidate point set.

[0025] In some embodiments, a standard voltage vector of the rectifier is determined.

[0026] Given a reference voltage and the current output voltage of the rectifier, a standard voltage vector can be determined based on an algorithm. The standard voltage vector represents the ideal control of the rectifier's switching state. If the rectifier's switching state can reach this standard voltage vector, then the rectifier's output voltage can reach the reference voltage.

[0027] However, since the voltage vector corresponding to the switching states of the rectifier does not change continuously and uniformly, but rather exhibits a discrete distribution, it is practically difficult to control the switching states to achieve a standard voltage vector. Therefore, it is necessary to select a suitable target switching state from the various switching states of the rectifier, so that the output voltage of the rectifier under the control of the target switching state is close to the reference voltage.

[0028] The relevant algorithms for determining the standard voltage vector will be described in detail in the subsequent embodiments of this disclosure, and will not be repeated here.

[0029] In some embodiments, a standard point corresponding to the standard voltage vector in a three-phase coordinate system is determined.

[0030] The standard voltage vector can be converted into a standard point in a three-phase coordinate system.

[0031] The standard voltage vector can be inversely transformed from the αβ coordinate system to the three-phase coordinate system to obtain the coordinates of the standard point. .

[0032] The standard point, after transformation, of the standard voltage vector is located inside a three-dimensional cube, representing the ideal three-phase voltage distribution.

[0033] In some embodiments, a preset set of points in the three-phase coordinate system is determined for the voltage vectors corresponding to all switching states of the rectifier.

[0034] All switching states of the rectifier can be determined, and the voltage vectors corresponding to all switching states can be transformed to a three-phase coordinate system. Each voltage vector corresponding to a switching state can be used to obtain a corresponding three-phase coordinate point, and the set of these three-phase coordinate points is a preset point set.

[0035] In a three-phase coordinate system, the points in these preset point sets represent the actual discrete switching states of the rectifier. The rectifier can only control the switching state to the switching state corresponding to the preset point set based on the corresponding voltage vector.

[0036] For example, in a three-phase NPC rectifier, the number of points in the preset point set is 27.

[0037] In some embodiments, a set of candidate points whose distance from the standard point is less than a first distance is determined from the preset set of points.

[0038] Points in a preset point set can be filtered to determine a candidate point set containing a smaller number of points.

[0039] Since a point in the three-phase coordinate system corresponds to a three-phase voltage vector, the closer the three-phase voltage vector is to the standard point in the three-phase coordinate system, the closer it is to the standard voltage vector, and the more likely it is to be the switching state with the best control effect among all switching states. Conversely, the farther the three-phase voltage vector is from the standard point in the three-phase coordinate system, the greater the deviation between the three-phase voltage vector and the standard voltage vector, and generally, the greater the difference between the output voltage and the reference voltage.

[0040] For example, filtering can be performed based on the distances between all points in a preset point set and a standard point. Points that are greater than or equal to a first distance from the standard point are discarded, while points that are less than the first distance from the standard point are retained as candidate points.

[0041] The first distance can be a preset distance. The smaller the first distance, the fewer points are included in the determined candidate point set.

[0042] It should be noted that the distance in this disclosure refers to the distance between two points in a three-phase coordinate system.

[0043] In some embodiments, a target voltage vector for adjusting the switching state of the rectifier is determined from the set of candidate points.

[0044] After determining the candidate point set, the target voltage vector for adjusting the switching state of the rectifier can be determined from the candidate point set.

[0045] For example, the voltage vector corresponding to the point closest to the standard point can be determined from the candidate point set as the target voltage vector.

[0046] For example, the cost function can be determined based on other factors such as cost and output voltage change rate, and then the target voltage vector corresponding to the point that minimizes the cost function can be determined from these candidate point sets based on the cost function.

[0047] After determining the standard voltage vector, this disclosure does not perform traversal calculations on all discrete voltage vectors. Instead, it converts the voltage vectors corresponding to all switching states and the standard voltage vector into three-phase coordinates. Then, based on the distance in the three-phase coordinate system, it filters the preset point set corresponding to all switching states to determine the candidate point set containing some points. This can significantly reduce the number of points that need to be calculated, speed up the determination of the target voltage vector, reduce the amount of calculation, shorten the control cycle, and improve efficiency.

[0048] In some embodiments, determining the standard voltage vector of the rectifier includes: determining a continuous set of standard voltage vectors.

[0049] Because the rectifier needs to be controlled in real time, under high-frequency control, each control cycle has a corresponding standard voltage vector. Therefore, the standard voltage vector and its corresponding standard point can be a continuous set.

[0050] In some embodiments, determining the standard point corresponding to the standard voltage vector in the three-phase coordinate system includes: determining the three-phase voltage vector of the standard voltage vector; and normalizing the three-phase voltage vector to determine the standard point corresponding to the three-phase coordinate system.

[0051] The three-phase voltage vector of the standard voltage vector can be determined. After determining the three-phase voltage vector, the three-phase voltage vector is normalized and mapped to eliminate the influence of dimensions. This is beneficial for determining the distance between the standard point and the preset point set, and the standard point can be processed more conveniently.

[0052] Alternatively, the standard voltage vector can be directly normalized and mapped to a standard point.

[0053] For example, the formula for mapping the standard voltage vector to a normalized three-phase coordinate system can be: (1) in, The standard vector is represented by its three-phase coordinates in a three-phase coordinate system. This is the DC voltage output by the rectifier; This is a transformation to the inverse coordinate system. Let be the standard voltage vector in the αβ coordinate system.

[0054] After normalizing the voltage vector, the influence of the output voltage on the coordinates of points in the coordinate system can be eliminated, thus making the points in the three-phase coordinate system have the same effect under different output voltages.

[0055] In some embodiments, determining the preset point set of voltage vectors corresponding to all switching states of the rectifier in the three-phase coordinate system includes: converting the voltage vectors corresponding to all switching states into three-phase voltage vectors, and determining the preset point set of the three-phase voltage vectors corresponding to all switching states in the three-phase coordinate system.

[0056] All switching states of the rectifier can be determined, and then the voltage vectors corresponding to these switching states can be converted into three-phase voltage vectors.

[0057] The number of switching states of a rectifier is finite, and these switching states typically correspond to multiple discrete voltage vectors. To facilitate switching control, voltage vectors along the αβ axis are generally used for control. Therefore, it is necessary to convert the voltage vectors of the switching states into three-phase voltage vectors, so as to represent the preset controllable switching states of the rectifier in a three-phase coordinate system.

[0058] After being converted into three-phase voltage vectors, the points corresponding to these three-phase voltage vectors can be determined in a three-phase coordinate system, and the set of these points is defined as a preset point set. The switching state of the rectifier can only be the switching state corresponding to the points in this preset point set. Therefore, regardless of whether the determined ideal standard voltage vector coincides with the preset point set, the voltage vector corresponding to the points in the preset point set can only be selected to control the switching of the rectifier.

[0059] In some embodiments, determining a set of candidate points whose distance from the standard point is less than a first distance from the preset point set includes: when the preset point set has the same spacing on the three-phase coordinate axes of the three-phase coordinate system, the first distance is the spacing of the preset point set on the three-phase coordinate axes.

[0060] If a preset set of points is determined for the voltage vectors of all switching states in a three-phase coordinate system, then normalization can be used to ensure that the points in the preset set are evenly spaced. Evenly spaced distribution means that the projections of the points in the preset set onto the three-phase coordinate axes are spaced at the same distance.

[0061] For example, in a three-phase NPC rectifier, the switching states of each phase correspond to -1, 0, and +1, respectively. Therefore, the total number of switching states is 3×3×3, a total of 27 switching states. These switching states correspond to 27 equally spaced points in the three-phase coordinate system.

[0062] After a standard point is determined in a three-phase coordinate system, it is usually difficult for the standard point to coincide exactly with any point in the preset point set. Therefore, on any coordinate axis of the three-phase coordinate system, the standard point may lie between two adjacent preset points. Compared with other points on any coordinate axis, the two preset points adjacent to the standard point have a higher probability of becoming the target point, and the corresponding voltage vector has a higher probability of being the target voltage vector.

[0063] In some embodiments, determining a set of candidate points whose distance from the standard point is less than a first distance from the preset point set includes: determining the set of candidate points from the preset point set, wherein the set of candidate points consists of points whose three-phase coordinates are adjacent to the standard point on all three-phase coordinate axes.

[0064] When the preset point set has the same spacing on the three-phase coordinate axes of the three-phase coordinate system, the first distance is the spacing of the preset point set on the three-phase coordinate axes.

[0065] For example, if the spacing between the preset point set on the three-phase coordinate axes of the three-phase coordinate system is 1, that is, the coordinate interval of the preset point set on any coordinate axis is 1, then points whose distance from the standard point is less than 1 are determined as candidate point sets. For example, if the coordinates of the standard point on any coordinate axis are 1 and 3, and the coordinates of the preset point set on any coordinate axis are exactly integers, then the coordinates of the candidate point set on that coordinate axis are 1 and 2.

[0066] Based on this embodiment, the preset point set can be quickly filtered based on the first distance, rapidly reducing the preset point set to a smaller set of candidate points. For example, for a preset point set consisting of 27 points in a three-phase NPC rectifier, it can be filtered to a set of 8 candidate points in a 2×2×2 grid adjacent to the coordinates of the standard point.

[0067] Candidate point set The formula can be: , (2) Where m_j is the coordinate of the standard point on the corresponding coordinate axis. The coordinates of the standard point in the three-phase coordinate system are given. The floor() algorithm is used to round down, and the ceil() algorithm is used to round up.

[0068] Based on this embodiment, a preset set of points can be quickly located through a simple rounding operation, and a standard point exists within the spatial region formed by this preset set of points.

[0069] In some embodiments, the distances between points in the candidate point set and the standard point can be determined respectively, and the point with the smallest distance can be determined as the target point, and the corresponding voltage vector can be the target voltage vector.

[0070] Without considering other factors and only taking into account the control effect, the smallest distance from the standard point means that the corresponding voltage vector is closest to the standard voltage vector. Therefore, under the control of the target voltage vector, the voltage output by the rectifier best matches the preset control effect.

[0071] However, in complex scenarios, the control of rectifiers needs to consider other factors besides the control effect. Therefore, the target voltage vector cannot be determined solely by considering the degree of proximity to the standard voltage vector.

[0072] In some embodiments, determining the target voltage vector for adjusting the switching state of the rectifier from the candidate point set includes: substituting the voltage vectors corresponding to the candidate point set into the cost function, and determining the voltage vector that minimizes the value of the cost function as the target voltage vector.

[0073] The preset cost function can be determined based on standard voltage, standard current, etc., to reflect the comprehensive control effect of the voltage vector corresponding to the switching state in multiple dimensions.

[0074] The more complex the cost function, the greater the computational load and the longer the computation time. Therefore, this disclosure selects points from the candidate point set to be substituted into the cost function for calculation, rather than calculating all points in the preset point set, which can reduce the computational load.

[0075] In some embodiments, the cost function is determined based on the components of the standard voltage vector along the α and β axes, the components of the candidate point set along the α and β axes, and the midpoint voltage.

[0076] The first term of the cost function is determined by the square of the difference between the standard voltage vector and the candidate point set along the α-axis; the second term is determined by the square of the difference between the standard voltage vector and the candidate point set along the β-axis; and the third term is determined by the square of the midpoint voltage.

[0077] For example, the cost function could be: (3) in, Let be the cost function corresponding to the i-th point in the candidate point set; , The standard voltage at time k is Component of direction; , Is the i-th voltage vector in Component of direction; For coefficients; This is the midpoint voltage.

[0078] Standard voltage in the cost function It can be determined by the following formula: (4) Where α is a coefficient; To control the duration of the cycle; Standard current; The actual current of the rectifier on the grid side is determined at time k. This is for disturbance estimation. Specific disturbance estimation... How to determine this will be described in detail later.

[0079] In some embodiments, the midpoint voltage is determined by the midpoint current, which is the current corresponding to the midpoint determined by each point in the candidate point set.

[0080] Midpoint current for: (5) Where S represents a point in the candidate point set. It is a three-phase current.

[0081] After determining the midpoint current, the midpoint voltage of the current cycle can be determined based on the midpoint voltage of the previous cycle, the midpoint current of the previous cycle, the capacitance, and the duration of the control cycle.

[0082] The formula for the midpoint voltage is: (6) in, This is the capacitance value of a single capacitor on the DC side of the rectifier.

[0083] Including the midpoint voltage as a term in the cost function allows the midpoint current and midpoint voltage of the target voltage vector determined based on the cost function to be as small as possible, resulting in better control performance.

[0084] The method for determining the standard voltage vector in this disclosure is described below.

[0085] In some embodiments, determining the standard voltage vector of the rectifier includes: determining a reference power based on the output voltage of the rectifier and a reference voltage; determining a grid power based on the grid voltage and grid current of the rectifier; determining a power disturbance based on the grid power and the standard voltage vector at the previous moment; and determining the standard voltage vector at the current moment based on the power disturbance, the reference power, and the grid power.

[0086] This disclosure employs a dual-loop predictive control method to determine the standard voltage vector. The overall structure includes an outer-loop DC bus voltage controller and an inner-loop three-phase current / power predictive controller. The outer loop can use an improved adaptive extended state observer (ESO) to generate a smooth, error-free, and disturbance-resistant power reference; the inner loop can use fast model predictive control (MPC). The control method of this disclosure enables the system to maintain excellent performance under both steady-state and transient (parameter mismatch) conditions.

[0087] Figure 2 This is a schematic flowchart illustrating a rectifier control method according to an embodiment of the present disclosure.

[0088] In some embodiments, the reference power is determined based on the output voltage of the rectifier and the reference voltage.

[0089] like Figure 2 As shown, based on the rectifier's output voltage and reference voltage... The reference power R can be determined. The reference power R is a complex power, which includes active power P and reactive power Q.

[0090] In some embodiments, the grid power is determined based on the grid voltage and grid current of the rectifier.

[0091] like Figure 2 As shown, the grid power W can be determined based on the grid voltage u and grid current i on the grid side of the rectifier. This grid power W is a complex power, which also includes active power P and reactive power Q.

[0092] In some embodiments, the power disturbance is determined based on the grid power and the standard voltage vector of the previous moment.

[0093] like Figure 2 As shown, based on the predictive extended state observer (PESO), the power disturbance Z2 at the current moment can be determined according to the input grid power W and the standard voltage vector U of the previous moment.

[0094] In some embodiments, the standard voltage vector at the current moment is determined based on the power disturbance, the reference power, and the grid power.

[0095] like Figure 2As shown, based on the control law, the input power disturbance Z2, the grid power W, and the reference power R can determine the standard voltage vector U at the current moment. This standard voltage vector can be used to control the switching state of the rectifier at the current moment, and can also be input to PESO to determine the power disturbance at the next moment.

[0096] The following section will provide a detailed explanation of how to determine the standard voltage vector and the power disturbance.

[0097] The rectifier system conforms to the continuous current model: (7) in, For output current, The output voltage of the rectifier. Let L be the grid voltage, and L and R be the inductance and resistance, respectively.

[0098] Discretize the discrete prediction model using the forward Euler method: (8) in, To control the duration of the cycle.

[0099] In some embodiments, a hyperlocal model can be set on the DC output side of the rectifier to determine disturbances.

[0100] The hyperlocal model on the DC side is as follows: (9) in, is the derivative of the DC-side output voltage, representing the rate of change of the output voltage; f represents the total disturbance, which includes disturbances caused by load changes, parameter uncertainties, etc.; u is the control quantity, i.e., the DC-side current; b is the input gain, which is a preset coefficient.

[0101] A first-order low-pass filter can be applied to the DC voltage sampling signal to suppress measurement noise and high-frequency ripple, and to prevent oscillations caused by noise.

[0102] A smooth voltage reference signal is then generated using a first-order reference follower to avoid overshoot and oscillation caused by step changes.

[0103] The extended state observer employs a second-order extended structure, which expands system disturbances into state variables. Fast and stable disturbance estimation is achieved through an observer gain constructed using an exponentially decaying form. The state update equation of the extended state observer can estimate the DC voltage dynamics and its disturbance terms in real time, enabling the controller to maintain stable performance even under parameter changes or complex abrupt changes. The update equation is as follows: (10) (11) in, This is a voltage estimate. The rate of change of the voltage estimate; This is an estimated current value. The rate of change of the current estimate; All are observer gains.

[0104] Determine the reference power based on the DC current and voltage: (12) in, The output current on the DC side can be found in the updated equation. The value; The output voltage on the DC side can be found in the update equation. The value of .

[0105] Determined reference power Used to input the control law to determine the target voltage vector.

[0106] For the inner-loop control law, a disturbance observer based on a hyperlocal model can be introduced to eliminate the dependence of the inner-loop predictive control on the parameters of inductor L and resistor R. This observer reduces system parameter variations, grid-side voltage fluctuations, and nonlinear factors to a total disturbance and uses PESO to estimate the total disturbance in real time, thereby more accurately determining the target voltage vector. A power transformation matrix can be defined. A linear mapping relationship between current dynamics and power change rate is established, and this matrix is ​​used to transform the control objective from the current domain to the power domain. Compared to the current domain, the power domain exhibits better robustness.

[0107] The defined control law is: (13) (14) (15) (16) in, For complex power reference vector ( Figure 2 The R value of the inner and outer ring roads is derived from the active power reference value. and reactive power Composition, reactive power can be 0; The power transformation matrix is ​​constructed using the voltage components in the current coordinate system and is used to describe the linear mapping relationship between voltage command and power change rate. It is the target voltage vector of the previous moment, and stores the voltage reference component of the previous sampling period; The power observation bias vector represents the residual between the power value estimated by the current observer and the actual calculated power value. This is the total disturbance estimate vector at the current moment, encompassing model parameter mismatch and external power grid disturbances. Figure 2 In Chinese, Z2 is used to represent it; The power state observation estimation vector at the current moment; The next time step predicted power estimate vector is obtained by calculating the PESO state update equation; The next time step total disturbance estimate vector is calculated using the PESO state update equation; The disturbance prediction vector is the disturbance estimation vector for the time after next (k+2) determined by linear extrapolation of the deviation between the disturbance estimate at the next time (k+1) and the current time (k). It is used to compensate for the calculation delay in digital control. The equivalent control voltage vector is the original reference voltage command generated through the inverse operation of the power change matrix; and It is the continuous voltage reference command that is finally assigned to the α-axis and β-axis, that is, the standard voltage vector; This is the final reference voltage vector in the complex domain; This refers to the duration of the sampling and control cycle in a discrete control system. b is the nominal value of the input gain of the control system; and State correction gain and disturbance estimation gain for the inner-loop power state extended observer; This is the disturbance prediction compensation factor, used to adjust the strength of disturbance extrapolation compensation.

[0108] Based on the above control law, the disturbance estimate Z2 can be determined, and a robust prediction model for the current at the next time step can be constructed for cost function calculation. The robust prediction model is as follows: (17) With this robust prediction model, the inner-loop MPC can maintain accurate current tracking even in the event of parameter mismatch (such as inductor saturation or temperature drift) without needing to obtain accurate inductance and resistance parameters.

[0109] Based on this embodiment, the dual-loop structure achieves high-performance control for the rectifier through the collaborative design of the outer-loop ESO and the inner-loop MPC. The outer-loop ESO can estimate DC voltage disturbances in real time and generate a smooth, dynamically consistent power reference, allowing the inner-loop MPC to avoid handling drastic changes during dynamic processes, thereby reducing current spikes and improving transient stability. The inner-loop MPC achieves high-precision current control and midpoint voltage balance through a candidate point set and a midpoint voltage-friendly cost function, and can quickly execute the power regulation commands of the outer loop.

[0110] The synergistic effect of these two factors enables the system to exhibit low THD (Total Harmonic Distortion) and high current quality under steady-state conditions, fast response and small overshoot under transient conditions, and strong robustness under parameter mismatch conditions. At the same time, it significantly reduces the computational load and is suitable for real-time implementation of processing modules.

[0111] Based on the above embodiments, the standard voltage vector can be determined. However, it should be noted that the above embodiments are merely examples of determining the standard voltage vector and should not limit the scope of protection of this disclosure.

[0112] Corresponding to the embodiments of the method for determining the switching state of a rectifier disclosed herein, this disclosure also provides embodiments of a corresponding apparatus for determining the switching state of a rectifier.

[0113] Please see Figure 3 , Figure 3 This is a block diagram of a device for determining the switching state of a rectifier according to one embodiment of this disclosure. Figure 3 As shown, the device for determining the switching state of the rectifier includes: The first processing unit 310 is configured to determine a standard voltage vector of the rectifier, wherein the output voltage of the rectifier is a reference voltage under the standard voltage vector; The second processing unit 320 is configured to determine the standard point corresponding to the standard voltage vector in the three-phase coordinate system; determine a preset set of points in the three-phase coordinate system corresponding to the voltage vectors of all switching states of the rectifier; and determine a set of candidate points from the preset set of points whose distance from the standard point is less than a first distance. The third processing unit 330 is configured to determine a target voltage vector from the candidate point set for adjusting the switching state of the rectifier.

[0114] In some embodiments, determining the standard point corresponding to the standard voltage vector in the three-phase coordinate system includes: determining the three-phase voltage vector of the standard voltage vector; and normalizing the three-phase voltage vector to determine the standard point corresponding to the three-phase coordinate system.

[0115] In some embodiments, determining the preset point set of voltage vectors corresponding to all switching states of the rectifier in the three-phase coordinate system includes: converting the voltage vectors corresponding to all switching states into three-phase voltage vectors, and determining the preset point set of the three-phase voltage vectors corresponding to all switching states in the three-phase coordinate system.

[0116] In some embodiments, determining a set of candidate points whose distance from the standard point is less than a first distance from the preset point set includes: when the preset point set has the same spacing on the three-phase coordinate axes of the three-phase coordinate system, the first distance is the spacing of the preset point set on the three-phase coordinate axes.

[0117] In some embodiments, determining a set of candidate points whose distance from the standard point is less than a first distance from the preset point set includes: determining the set of candidate points from the preset point set, wherein the set of candidate points consists of points whose three-phase coordinates are adjacent to the standard point on all three-phase coordinate axes.

[0118] In some embodiments, determining the target voltage vector for adjusting the switching state of the rectifier from the candidate point set includes: substituting the voltage vectors corresponding to the candidate point set into the cost function, and determining the voltage vector that minimizes the value of the cost function as the target voltage vector.

[0119] In some embodiments, determining the standard voltage vector of the rectifier includes: determining a reference power based on the output voltage of the rectifier and a reference voltage; determining a grid power based on the grid voltage and grid current of the rectifier; determining a power disturbance based on the grid power and the standard voltage vector at the previous moment; and determining the standard voltage vector at the current moment based on the power disturbance, the reference power, and the grid power.

[0120] The specific implementation process of the functions and roles of each unit in the above device can be found in the implementation process of the corresponding steps in the above method, and will not be repeated here.

[0121] Embodiments of this disclosure also provide an electronic device, including: a processor and a memory; the memory for storing a computer program; and the processor for executing a method for determining the switching state of a rectifier as described in any of the above embodiments by invoking the computer program.

[0122] Embodiments of this disclosure also provide a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements a method for determining the switching state of a rectifier as described in any of the above embodiments.

[0123] Embodiments of this disclosure also provide a computer program product, including a computer program that, when executed by a processor, implements the methods described in any of the foregoing embodiments.

[0124] Please see Figure 4 , Figure 4 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 4 As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system).

[0125] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0126] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0127] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device as shown by a landing page for an app. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, which can be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0128] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0129] The computer device also includes a communication interface 30 for communicating with other devices or communication networks.

[0130] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0131] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

[0132] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0133] The methods and apparatus provided in the embodiments of this disclosure have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this disclosure. The descriptions of the embodiments above are only for the purpose of helping to understand the methods and core ideas of this disclosure. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this disclosure. Therefore, the content of this specification should not be construed as a limitation of this disclosure.

Claims

1. A method for determining the switching state of a rectifier, characterized in that, The method includes: Determine the standard voltage vector of the rectifier, wherein the output voltage of the rectifier under the standard voltage vector is the reference voltage; Determine the standard point corresponding to the standard voltage vector in the three-phase coordinate system; Determine a preset set of points in the three-phase coordinate system for the voltage vectors corresponding to all switching states of the rectifier, and determine a set of candidate points from the preset set of points whose distance from the standard point is less than a first distance; The target voltage vector for adjusting the switching state of the rectifier is determined from the set of candidate points.

2. The method according to claim 1, characterized in that, Determining the standard point corresponding to the standard voltage vector in the three-phase coordinate system includes: Determine the three-phase voltage vectors of the standard voltage vector; The three-phase voltage vectors are normalized and mapped to determine the corresponding standard points in the three-phase coordinate system.

3. The method according to claim 1, characterized in that, The step of determining the preset set of points in the three-phase coordinate system corresponding to the voltage vectors of all switching states of the rectifier includes: The voltage vectors corresponding to all switching states are converted into three-phase voltage vectors, and the set of points corresponding to the three-phase voltage vectors of all switching states is determined as the preset set of points in the three-phase coordinate system.

4. The method according to claim 1, characterized in that, The step of determining a set of candidate points from the preset set of points whose distance from the standard point is less than a first distance includes: When the preset point set has the same spacing on the three-phase coordinate axes of the three-phase coordinate system, the first distance is the spacing of the preset point set on the three-phase coordinate axes.

5. The method according to claim 4, characterized in that, The step of determining a set of candidate points from the preset set of points whose distance from the standard point is less than a first distance includes: The candidate point set is determined from the preset point set, wherein the points whose three-phase coordinates are adjacent to the standard point on all three-phase coordinate axes are the candidate point set.

6. The method according to claim 1, characterized in that, Determining the target voltage vector from the candidate point set for adjusting the switching state of the rectifier includes: Substitute the voltage vectors corresponding to the candidate point set into the cost function, and determine the voltage vector that minimizes the value of the cost function as the target voltage vector.

7. The method according to claim 1, characterized in that, The determination of the standard voltage vector of the rectifier includes: The reference power is determined based on the output voltage of the rectifier and the reference voltage. The grid power is determined based on the grid voltage and grid current of the rectifier. The power disturbance is determined based on the grid power and the standard voltage vector of the previous moment; The standard voltage vector at the current moment is determined based on the power disturbance, the reference power, and the grid power.

8. A device for determining the switching state of a rectifier, characterized in that, The device includes: The first processing unit is configured to determine a standard voltage vector of the rectifier, wherein the output voltage of the rectifier is a reference voltage under the standard voltage vector; The second processing unit is configured to determine the standard point corresponding to the standard voltage vector in the three-phase coordinate system; determine a preset set of points in the three-phase coordinate system corresponding to the voltage vectors of all switching states of the rectifier; and determine a set of candidate points from the preset set of points whose distance from the standard point is less than a first distance. The third processing unit is configured to determine, from the set of candidate points, a target voltage vector for adjusting the switching state of the rectifier.

9. An electronic device, characterized in that, include: Processor, memory; The memory is used to store computer programs; The processor is configured to execute, by invoking the computer program, a method for determining the switching state of the rectifier as described in any one of claims 1-7.

10. A computer program product, characterized in that, Includes a computer program, which, when executed by a processor, implements a method for determining the switching state of a rectifier as described in any one of claims 1 to 7.

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