Control method and device for a single-stage rectifier

Abstract

The present application provides a control method and device for a single-stage rectifier. The method combines a proportional-integral controller, a proportional-resonant controller with finite control set model predictive control, and can achieve the control of three parts in the target system, namely grid current, inductor current, and load voltage. The method calculates the standard value of the grid current by the proportional-integral controller according to the voltage difference between the standard value and the target value of the load voltage; then inputs the current difference between the standard value of the grid current and the target value into the proportional-resonant controller, and further calculates the standard value of the inductor current; inputs the standard value of the inductor current into the finite control set model predictive control module for calculation, and outputs the corresponding switch control state, thereby realizing the precise control of the target system and improving the rectification efficiency of the single-stage rectifier.

Description

Technical Field

[0001] The present application relates to the technical field of rectifiers, and particularly to a control method and device for a single-stage rectifier. Background Art

[0002] A rectifier is a power electronic device used to convert alternating current (AC) into direct current (DC) to meet the requirements of various devices in a power system for DC power supplies. The rectifier can be connected to circuit components such as power generation equipment, energy storage systems, and DC loads. It can not only stabilize the voltage output but also reduce electromagnetic interference in the circuit, thereby improving the operation efficiency and reliability of the equipment.

[0003] The rectifier rectifies the input alternating current through internal electronic components such as diodes and transistors to output stable direct current. According to the number of stages of the rectifier, the rectifier can be divided into a two-stage rectifier and a single-stage rectifier. Since the single-stage rectifier has a simple structure, low control complexity, and strong scalability, the single-stage rectifier is used in the power system to convert direct current. However, the single-stage rectifier has the problem of discontinuous grid current, so a specific buck-boost topology needs to be connected to the front stage of the single-stage rectifier to maintain the continuity of the circuit.

[0004] For a single-stage rectifier with a buck-boost topology, the rectifier can be controlled by a PI / PR (Proportional Integral / Proportional Resonant) controller to ensure the stable operation of the power system. However, the process of adjusting the parameters of the PI / PR controller is relatively complex, which will reduce the rectification efficiency of the single-stage rectifier. Summary of the Invention

[0005] The present application provides a control method and device for a single-stage rectifier to solve the problem of low rectification efficiency of the single-stage rectifier.

[0006] In a first aspect, the present application provides a control method for a single-stage rectifier, including the following steps:

[0007] Detect the target load voltage of the load in the target system, where the target system includes a power grid, a single-stage rectifier, a buck-boost converter, and a load;

[0008] Calculate the voltage difference between the target load voltage and the standard load voltage;

[0009] Input the voltage difference into a proportional integral controller to obtain a standard grid current;

[0010] Detect the target grid current of the power grid;

[0011] Calculate the current difference between the target grid current and the standard grid current;

[0012] Input the current difference into a proportional-resonant controller to obtain a standard inductor current;

[0013] Calculate a predicted value based on the standard inductor current, and set a switching control state of the target system according to the predicted value; the predicted value is calculated by a finite control set model predictive control module based on the standard inductor current.

[0014] Optionally, the buck-boost converter includes a pre-stage switch, the pre-stage switch includes a first switch, a second switch, a third switch, and a fourth switch, the single-stage rectifier includes a post-stage switch, and the post-stage switch includes a fifth switch and a sixth switch; the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch each include two on-off states, and the on-off states include an on state and an off state; the target system is configured with at least three switching control states, and the on-off states of the pre-stage switch are different in different switching control states.

[0015] Optionally, obtaining the standard grid current includes: obtaining an adjustment coefficient of the proportional-integral controller, where the adjustment coefficient includes a proportional adjustment coefficient and an integral adjustment coefficient; calculating an amplitude adjustment amount according to the adjustment coefficient and the voltage difference; obtaining a grid current phase angle, where the grid current phase angle is obtained by a phase-locked loop module sampling the grid voltage of the power grid; calculating the standard grid current through the grid current phase angle and the amplitude adjustment amount.

[0016] Optionally, calculating the amplitude adjustment amount according to the adjustment coefficient and the voltage difference includes: calculating a first product of the proportional adjustment coefficient and the voltage difference; calculating an integral value of the voltage difference with respect to time; calculating a second product of the integral adjustment coefficient and the integral value; calculating the amplitude adjustment amount according to a sum value of the first product and the second product.

[0017] Optionally, calculating the standard grid current through the grid current phase angle and the amplitude adjustment amount includes: calculating a third product of the grid current phase angle and time; calculating a sine value of the third product; calculating the standard grid current according to a product of the sine value and the third product.

[0018] Optionally, obtaining the standard inductor current includes: obtaining a control resonance and a control frequency of the proportional-resonant controller, where the control resonance includes a proportional resonance and an integral resonance, and the control frequency includes a resonance frequency and a cut-off frequency; constructing a transfer function according to the control resonance, the control frequency, and the grid current phase angle, where the grid current phase angle is obtained by a phase-locked loop module sampling the grid voltage of the power grid; calculating the standard inductor current through the transfer function.

[0019] Optionally, the transfer function is constructed according to the following formula:

[0020]

[0021] where kpr is the proportional resonance, kr is the resonance gain, ωc is the resonance frequency, ωr is the cut-off frequency, s is the complex frequency variable in the frequency domain and is the differential operator of time t.

[0022] Optionally, calculating the predicted value based on the standard inductor current includes: calculating the predicted value of the inductor current at the next moment; constructing a cost function through the predicted value and the standard inductor current; calculating the cost function value based on the switch control state and the cost function, and the cost function value has an associated relationship with the switch control state.

[0023] Optionally, setting the switch control state of the target system according to the predicted value includes: extracting the target cost function value, where the target cost function value is the minimum cost function value; outputting the target control state according to the target cost function value, where the target control state is the switch control state associated with the target cost function value; setting the on-off state of the pre-stage switch according to the target control state.

[0024] In a second aspect, some embodiments of the present application provide a control device for a single-stage rectifier, including a target system and an algorithm control system. The target system includes a power supply network, a single-stage rectifier, a buck-boost converter, and a load. The algorithm control system is configured to:

[0025] Detect the target load voltage of the load;

[0026] Calculate the voltage difference between the target load voltage and the standard load voltage;

[0027] Input the voltage difference into a proportional-integral controller to obtain a standard grid current;

[0028] Detect the target grid current of the power supply network;

[0029] Calculate the current difference between the target grid current and the standard grid current;

[0030] Input the current difference into a proportional-resonance controller to obtain a standard inductor current;

[0031] Calculate a predicted value based on the standard inductor current, and set the switch control state of the target system according to the predicted value; the predicted value is calculated by a finite control set model predictive control module according to the standard inductor current.

[0032] As can be seen from the above technical solutions, a control method and device for a single-stage rectifier provided by the present application can detect the target load voltage of a load in a target system. The target system includes a power grid, a single-stage rectifier, a buck-boost converter, and a load. Then, calculate the voltage difference between the target load voltage and the standard load voltage, and input the voltage difference into a proportional-integral controller to obtain a standard grid current. Detect the target grid current of the power grid, and calculate the current difference between the target grid current and the standard grid current. Then, input the current difference into a proportional-resonant controller to obtain a standard inductor current. Next, calculate a predicted value based on the standard inductor current, and set the switching control state of the target system according to the predicted value. The predicted value is calculated by a finite control set model predictive control module based on the standard inductor current. The method can simultaneously meet the control requirements of grid current, inductor current, and load voltage. Through the combined action of the proportional-integral controller and the resonant integral controller, accurate tracking of the grid current and the inductor current is achieved. At the same time, by utilizing the prediction ability of the finite control set model predictive control module, the switching control state of the target system is optimized, thereby improving the dynamic performance and steady-state accuracy of the target system. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. 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.

[0034] Figure 1 It is a topological structure diagram of a rectifier provided by some embodiments of the present application;

[0035] Figure 2 It is a topological structure diagram of a buck-boost converter provided by some embodiments of the present application;

[0036] Figure 3 It is a topological structure diagram of a target system provided by some embodiments of the present application;

[0037] Figure 4 It is a schematic flowchart of a control method for a single-stage rectifier provided by some embodiments of the present application;

[0038] Figure 5 It is a schematic flowchart of calculating a standard grid current provided by some embodiments of the present application;

[0039] Figure 6 It is a schematic flowchart of calculating a standard inductor current provided by some embodiments of the present application;

[0040] Figure 7Schematic flowchart of setting the switch control state provided by some embodiments of the present application;

[0041] Figure 8 Architecture diagram of the single-stage rectifier control method provided by some embodiments of the present application;

[0042] Figure 9 Structural diagram of the single-stage rectifier control device provided by some embodiments of the present application. Detailed implementation manners

[0043] To make the objectives and implementation manners of the present application clearer, the following will clearly and completely describe the exemplary implementation manners of the present application with reference to the accompanying drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only a part rather than all of the embodiments of the present application.

[0044] The following will explain the embodiments in detail, and the examples are shown in the accompanying drawings. When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following embodiments do not represent all the implementation manners consistent with the present application. They are only examples of the systems and methods consistent with some aspects of the present application detailed in the claims.

[0045] It should be noted that the brief description of the terms in the present application is only for facilitating the understanding of the following described implementation manners, rather than intending to limit the implementation manners of the present application. Unless otherwise specified, these terms should be understood in their ordinary and general meanings.

[0046] The terms "first", "second", "third", etc. in the specification, claims and the above accompanying drawings of the present application are used to distinguish similar or like objects or entities, and do not necessarily mean to limit a specific order or sequence, unless otherwise noted. It should be understood that such terms can be interchanged under appropriate circumstances.

[0047] The terms "including" and "having" and any variations thereof are intended to cover but not exclude inclusion. For example, a product or device including a series of components does not necessarily have to be limited to all the clearly listed components, but may include other components not clearly listed or inherent to these products or devices.

[0048] A rectifier is an electronic power device used to convert alternating current (AC) into direct current (DC), and can be applied to power supply technology fields such as new energy. For example, in the new energy field, a rectifier can connect renewable energy power generation equipment with energy storage systems, DC loads, etc., so as to ensure the efficient and stable operation of the system. Moreover, the rectifier can not only stabilize the voltage output, but also reduce the electromagnetic interference in the circuit, thereby improving the operation efficiency and reliability of the system.

[0049] In some embodiments, the working process of the rectifier is to rectify the input alternating current through internal electronic components such as diodes, transistors, electronic power switch tubes, etc. For example, as Figure 1 shown, Figure 1 is a topology structure of a rectifier. The rectifier may include at least two electronic power switch tubes, so as to convert the AC input into a DC output.

[0050] In some embodiments, the rectifier may include a first-stage rectifier and a second-stage rectifier. The first-stage rectifier is also called a single-stage rectifier. Among them, the second-stage rectifier needs to use a diode bridge on the grid side. However, the design of the above-mentioned diode bridge is prone to problems such as inconsistent power factor and high total harmonic distortion, which will affect the operation efficiency and reliability of the system. Therefore, in power supply technology fields such as the new energy field, a single-stage rectifier is used to convert direct current. The single-stage rectifier has a simple structure, high cost-effectiveness, low control complexity, small size and strong scalability.

[0051] However, since the single-stage rectifier only allows one half-cycle of the alternating current to pass through, there will be a short intermittent period between each half-cycle, that is, the single-stage rectifier has the problem of discontinuous grid circuit. For this reason, in some embodiments, a buck-boost converter is connected to the front stage of the single-polarity rectifier. The buck-boost converter includes a buck-boost topology structure, such as a Boost boost circuit or a Buck buck circuit, so as to improve the problem of discontinuous grid circuit existing in the single-polarity rectifier.

[0052] For example, as Figure 2 shown, Figure 2 is a topology structure diagram of a buck-boost converter. Connecting the a and b ends of the buck-boost converter to the front stage of the single-stage rectifier and connecting the c and d ends to the power grid can dynamically adjust the input voltage of the single-stage rectifier, thereby improving the problem of discontinuous grid circuit.

[0053] For a single-stage rectifier connected with a buck-boost topology structure, in some embodiments, the single-stage rectifier can be controlled by a PI / PR (Proportional Integral / Proportional Resonant) controller. However, in the control process, the process of adjusting the PI / PR controller parameters is relatively complex, which will increase the difficulty of system design and maintenance.

[0054] To reduce complexity, in some embodiments, a single-stage rectifier can be controlled by finite control set model predictive control (FCS-MPC). Among them, the structure of the finite control set model predictive control is simple, which can reduce the difficulty of system design and maintenance. However, the finite control set model predictive control needs to traverse multiple switching states in the system, increasing the computational burden of the system, resulting in a decrease in the response speed of the single-stage rectifier, thereby affecting the rectification efficiency of the single-stage rectifier.

[0055] For this reason, some embodiments of the present application provide a control method for a single-stage rectifier, and the method can control a target system. Among them, the target system may include a power supply network, a single-stage rectifier, a buck-boost converter, and a load. The power supply network can be connected to the buck-boost converter, the buck-boost converter can be connected to the front stage of the single-stage rectifier, and the rear stage of the single-stage rectifier is connected to the load, so as to achieve rectification based on charging / discharging between the power supply network and the load.

[0056] In some embodiments, the target system further includes an LC input filter. The target system can connect the power supply network and the buck-boost converter through the LC input filter, which can filter out high-frequency noise and clutter in the power grid, improve the power supply quality, and further improve the reliability and stability of the target system. For example, as Figure 3 shown, Figure 3 is a topological structure diagram of the target system provided by some embodiments of the present application.

[0057] In some embodiments, the buck-boost converter includes a front-stage switch, and the front-stage switch includes a first switch, a second switch, a third switch, and a fourth switch; the single-stage rectifier includes a rear-stage switch, and the rear-stage switch includes a fifth switch and a sixth switch. The front-stage switch and the rear-stage switch can use power electronic switching tubes, and each switch has two on-off states, namely the on state and the off state. That is, the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch each include two on-off states, and the on-off states include the on state and the off state.

[0058] For example, as Figure 3 shown, the front-stage switches included in the buck-boost converter are S1, S2, S3, and S4 respectively, and the rear-stage switches included in the single-stage rectifier are S5 and S6 respectively. The above six switches can be configured with six corresponding switch control states according to the topological characteristics. As shown in the following table, the off states of S3, S4, S5, and S6 in the single-stage rectifier can be determined by the polarity v g of the grid voltage in the power supply network. Among them, ON represents the on state, and OFF represents the off state.

[0059]

[0060]

[0061] Obviously, when v g > 0 (zc = 1), S3 and S5 are turned off, and S4 and S6 are turned on; when v g < 0 (zc = 0), S3 and S5 are turned on, and S4 and S6 are turned off. Therefore, when controlling the target system, only the first switch and the second switch in the front-stage switch need to be controlled, that is, Figure 3 the S1 and S2 shown. That is to say, by controlling the on-off states of the first switch and the second switch, the charging and discharging of the inductor can be realized, that is, the control of the inductor current; and the inductor current depends on the grid current, so in order to realize the regulation of the load voltage of the single-stage rectifier, it is necessary to control the inductor current and the grid current.

[0062] For this purpose, as Figure 4 shown, the control method of the single-stage rectifier provided by some embodiments of the present application may include the following steps:

[0063] S1: Detect the target load voltage of the load in the target system.

[0064] Wherein, the target load voltage is the actual load voltage V dc in the target system, that is, Figure 3 the actual voltage at the current moment across the load shown. After detecting the target load voltage, the standard grid current can be determined by calculating the error between the target load voltage V dc and the given load voltage V dc * .

[0065] For the sake of convenience of description, in some embodiments of the present application, the given values of various indexes are represented as standard values, and the actual values of various indexes are represented as target values. For example, the given load voltage can be represented as the standard load voltage, the actual load voltage can be represented as the target load voltage; the given grid current can be represented as the standard grid current, the actual grid current can be represented as the target grid current, etc.

[0066] S2: Calculate the voltage difference between the target load voltage and the standard load voltage.

[0067] Therefore, after detecting the target load voltage V dc , calculate the difference value between the target load voltage V dc and the standard load voltage V dc * , that is, the voltage difference. For example, represent the voltage difference between the target load voltage V dc and the standard load voltage V dc * as e v , and the voltage difference e v can be calculated according to the following formula:

[0068]

[0069] S3: Input the voltage difference into a proportional-integral controller to obtain a standard grid current.

[0070] After calculating the voltage difference e between the target load voltage V dc and the standard load voltage V dc * , input the voltage difference e v into a proportional-integral (PI) controller, so as to calculate a standard grid current based on the proportional-integral controller. For example, as v shown, Figure 5 is a schematic flow diagram for calculating the standard grid current. Figure 5 That is, in some embodiments, the adjustment coefficient of the proportional-integral controller can be obtained, and then the amplitude adjustment amount is calculated according to the adjustment coefficient and the voltage difference, and the grid current phase angle is obtained. Among them, the adjustment coefficient includes a proportional adjustment coefficient and an integral adjustment coefficient, and the grid current phase angle is obtained by sampling the grid voltage of the power supply network by a phase-locked loop module. Then, the standard grid current is calculated through the grid current phase angle and the amplitude adjustment amount.

[0072] For the calculation of the amplitude adjustment amount, in some embodiments, calculate the first product of the proportional adjustment coefficient and the voltage difference, and calculate the integral value of the voltage difference with respect to time. Then calculate the second product of the integral adjustment coefficient and the integral value, and calculate the amplitude adjustment amount according to the sum value of the first product and the second product.

[0073] In some embodiments, calculate the third product of the grid current phase angle and time, and then calculate the sine value of the third product. Then, calculate the standard grid current according to the product of the sine value and the third product.

[0074] For example, after calculating the voltage difference ev between the target load voltage Vdc and the standard load voltage Vdc*, input the voltage difference ev into the PI controller according to the following formula:

[0075]

[0076]

[0077] where K p is the proportional adjustment coefficient, K i is the integral adjustment coefficient, e v is the voltage difference, t is time, and I g * is the amplitude of the inductor current, that is, the amplitude adjustment amount. Then, according to the obtained amplitude adjustment amount I g * , calculate the standard grid current according to the following formula:

[0077]

[0078] In the formula, ω is the phase angle of the grid current, which is obtained by sampling the grid voltage of the power grid by a phase-locked loop (PLL) module according to the phase angle of the grid voltage.

[0079] S4: Detect the target grid current of the power grid.

[0080] After calculating the standard grid circuit, detect the actual grid current of the power grid, that is, the target grid current. That is to say, Figure 3 the current at both ends of the shown v g After detecting the target grid current, the standard inductor current can be determined by calculating the error between the target grid current i g and the standard grid current i g *

[0081] S5: Calculate the current difference between the target grid current and the standard grid current.

[0082] Therefore, after detecting the target grid current i g , calculate the difference value between the target grid current i g and the standard grid current i g * , that is, the current difference. For example, express the current difference between the target grid current i g and the standard grid current i g * as e ig , and the current difference e ig can be calculated according to the following formula:

[0083]

[0084] S6: Input the current difference into a proportional-resonant controller to obtain the standard inductor current.

[0085] Since the tracking performance of the proportional-resonant (PR) controller is better, after calculating the current difference e g between the target grid current i g * and the standard grid current i ig , input the current difference e ig into the proportional-resonant controller, and thus calculate the standard inductor current based on the proportional-resonant controller. For example, as Figure 6 shown, Figure 6 is a schematic flow diagram for calculating the standard inductor current.

[0086] That is, in some embodiments, the control resonance and control frequency of the proportional resonance controller can be obtained, and then a transfer function is constructed according to the control resonance, control frequency, and grid current phase angle. Among them, the control resonance includes proportional resonance and integral resonance, the control frequency includes resonance frequency and cut-off frequency, and the grid current phase angle is obtained by sampling the grid voltage of the power supply network by a phase-locked loop module. Then, the standard inductor current is calculated through the transfer function.

[0087] In some embodiments, the transfer function is constructed according to the following formula:

[0088]

[0089] In the formula, kpr is the proportional resonance, kr is the resonance gain, ωc is the resonance frequency, ωr is the cut-off frequency, s is the complex frequency variable in the frequency domain, which is the differential operator of time t.

[0090] S7: Calculate the predicted value based on the standard inductor current, and set the switching control state of the target system according to the predicted value.

[0091] After calculating the standard inductor current value, the corresponding predicted value can be calculated through the standard inductor current value, and then the on-off state of the pre-stage switch is set according to the predicted value, so that the target system switches to different switching control states, thereby realizing the control of the single-stage rectifier.

[0092] In some embodiments, the target system is configured with at least 3 switching control states, and the on-off states of the pre-stage switches are different in different switching control states. For example, as Figure 3 shown in the topological structure, for the control of the pre-stage switches S1 and S2, 3 switching control states shown in the following table are configured, and the following three switching control states can be set through the predicted value calculated based on the standard inductor current.

[0093]

[0094] In the embodiments of the present application, in order to reduce the calculation burden of the target system, the predicted value is calculated by the finite control set model predictive control (FCS-MPC) module according to the standard inductor current. For example, as Figure 7 shown, Figure 7 is a schematic flow chart for setting the switching control state.

[0095] That is, in some embodiments, the predicted value of the inductor current at the next moment is calculated, and a cost function is constructed through the predicted value and the standard inductor current. Then, the cost function value is calculated based on the switching control state and the cost function. Among them, the cost function value has an associated relationship with the switching control state.

[0096] Correspondingly, for the setting of the switch control state, in some embodiments, the target cost function value is extracted, and then the target control state is output according to the target cost function value. Among them, the target cost function value is the minimum cost function value, and the target control state is the switch control state associated with the target cost function value. Then, the on-off state of the pre-stage switch is set according to the target control state.

[0097] For example, under multiple switch control states, the variable values at the k+1 moment are predicted, and a cost function is established to evaluate and calculate the error value between the predicted value and the standard value. Finally, the switch state vector with the minimum cost function value is selected, and the corresponding switch control state is set. As Figure 3 shown in the topological result, switches S1 and S2 correspond to three switch control states.

[0098] Among them, the inductor current i p at the k+1 moment is predicted according to the following formula:

[0099]

[0100] +((1 - zc)(1 - S2) - zc(1 - S1)V dc +i p (k)

[0101] In the formula, Ts is the sampling frequency value; i p (k) is the target inductor current value at the k moment, obtained by sampling; S1 and S2 have a value of 1 when they are in the on state, and a value of 0 when S1 and S2 are off; v Cf is the capacitor voltage value, calculated according to the following formula:

[0102] v Cf =v g -v Lf

[0103] In the formula, the value of the grid voltage v g is obtained by sampling, and the value of the filter inductor voltage v Lf is deduced backward according to the following Euler formula:

[0104]

[0105] Then, the cost function is constructed according to the following formula:

[0106]

[0107] The three switch control states are respectively put into the cost function, and the corresponding cost function values are calculated. Then, according to the principle of the minimum cost function, the switch control state with the minimum cost function value among the three switch control states is selected for output, so as to realize the control of the target system.

[0108] Exemplarily, as Figure 8 shown, the control method of the single-stage rectifier provided by the embodiments of the present application can be divided into three parts. The first part is used to calculate the standard grid current and is implemented based on a PI controller; the second part is used to calculate the standard inductor current and is implemented based on a PR controller; the third part is used to set the switch control state and is implemented based on an FCS-MPC module. As Figure 8 shown, the control method provided by the present application can combine the advantages of the PI-PR controller and FCS-MPC at the same time, reduce the complexity of controller adjustment, and for the switch characteristics in the single-stage rectifier, reduce the six switch states that need to be traversed by FCS-MPC to three, while ensuring the control performance, reducing the computational burden of the target system.

[0109] Based on the above control method of the single-stage rectifier, some embodiments of the present application further provide a control device for the single-stage rectifier, which can be used to execute the control method of the single-stage rectifier provided by the above embodiments. Among them, as Figure 9 shown, the device includes a target system 910 and an algorithm control system 920. The target system 910 includes a power grid 911, a single-stage rectifier 912, a buck-boost converter 913, and a load 914; as Figure 4 shown, the algorithm control system 920 is configured to execute the following program steps:

[0110] S1: Detect the target load voltage of the load;

[0111] S2: Calculate the voltage difference between the target load voltage and the standard load voltage;

[0112] S3: Input the voltage difference into a proportional-integral controller to obtain the standard grid current;

[0113] S4: Detect the target grid current of the power grid;

[0114] S5: Calculate the current difference between the target grid current and the standard grid current;

[0115] S6: Input the current difference into a proportional-resonant controller to obtain the standard inductor current;

[0116] S7: Calculate a predicted value based on the standard inductor current, and set the switch control state of the target system according to the predicted value; the predicted value is calculated by a finite control set model predictive control module according to the standard inductor current.

[0117] As can be seen from the above technical solutions, a control method and device for a single-stage rectifier provided by this application can detect the target load voltage of a load in a target system. Among them, the target system includes a power grid, a single-stage rectifier, a buck-boost converter, and a load. Then, calculate the voltage difference between the target load voltage and the standard load voltage, and input the voltage difference into a proportional-integral controller to obtain a standard grid current. Detect the target grid current of the power grid, and calculate the current difference between the target grid current and the standard grid current. Then, input the current difference into a proportional-resonant controller to obtain a standard inductor current. Then, calculate a predicted value based on the standard inductor current, and set the switching control state of the target system according to the predicted value. Among them, the predicted value is calculated by a finite control set model predictive control module based on the standard inductor current.

[0118] The control method and device for the single-stage rectifier provided by the embodiments of this application can simultaneously meet the control requirements of grid current, inductor current, and load voltage. Through the combined action of the proportional-integral controller and the resonant integral controller, accurate tracking of the grid current and the inductor current is achieved. At the same time, by utilizing the prediction ability of the finite control set model predictive control module, the switching control state of the target system is optimized, thereby improving the dynamic performance and steady-state accuracy of the target system. In addition, the control method for the single-stage rectifier provided by this application also has the advantages of simple structure, easy implementation, and strong robustness, and can be applied to various single-stage rectifiers with buck-boost structures.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, rather than to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application.

[0120] For the sake of convenience in explanation, the above description has been made in conjunction with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. According to the above teachings, various modifications and variations can be obtained. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, so that those skilled in the art can better use the embodiments and various different modified embodiments suitable for specific usage considerations.

Claims

1. A control method for a single-stage rectifier, characterized in that Including: Detecting a target load voltage of a load in a target system, where the target system includes a power grid, a single-stage rectifier, a buck-boost converter, and a load; Calculating a voltage difference between the target load voltage and a standard load voltage; Inputting the voltage difference into a proportional-integral controller to obtain a standard grid current; The obtaining the standard grid current includes: Obtaining an adjustment coefficient of the proportional-integral controller, where the adjustment coefficient includes a proportional adjustment coefficient and an integral adjustment coefficient; calculating an amplitude adjustment amount according to the adjustment coefficient and the voltage difference; Obtaining a grid current phase angle, which is obtained by a phase-locked loop module sampling the grid voltage of the power grid; Calculating the standard grid current through the grid current phase angle and the amplitude adjustment amount; The calculating the amplitude adjustment amount according to the adjustment coefficient and the voltage difference includes: Calculating a first product of the proportional adjustment coefficient and the voltage difference; Calculating an integral value of the voltage difference with respect to time; Calculating a second product of the integral adjustment coefficient and the integral value; Calculating the amplitude adjustment amount according to a sum value of the first product and the second product; The calculating the standard grid current through the grid current phase angle and the amplitude adjustment amount includes: Calculating a third product of the grid current phase angle and time; Calculating a sine value of the third product; Calculating the standard grid current according to a product of the sine value and the third product; Detecting a target grid current of the power grid; Calculating a current difference between the target grid current and the standard grid current; Inputting the current difference into a proportional-resonant controller to obtain a standard inductor current; The obtaining the standard inductor current includes: Obtaining a control resonance and a control frequency of the proportional-resonant controller, where the control resonance includes a proportional resonance and an integral resonance, and the control frequency includes a resonance frequency and a cut-off frequency; Constructing a transfer function according to the control resonance, the control frequency, and the grid current phase angle, where the grid current phase angle is obtained by a phase-locked loop module sampling the grid voltage of the power grid; Calculating the standard inductor current through the transfer function; Constructing the transfer function according to the following formula: In the formula, kpr is the proportional resonance, kr is the resonance gain, ωc is the resonance frequency, ωr is the cut-off frequency, s is a complex frequency variable in the frequency domain and is a differential operator of time t; Calculating a predicted value based on the standard inductor current, and setting a switching control state of the target system according to the predicted value; the predicted value is calculated by a finite control set model predictive control module according to the standard inductor current; The buck-boost converter includes a front-stage switch, where the front-stage switch includes a first switch, a second switch, a third switch, and a fourth switch, and the single-stage rectifier includes a rear-stage switch, where the rear-stage switch includes a fifth switch and a sixth switch; the first switch, the second switch, the third switch, the fourth switch, the fifth switch, and the sixth switch each include two on-off states, and the on-off states include an on state and an off state; The target system is configured with at least three switch control states, and the on-off states of the pre-stage switch are different in different switch control states.

2. The control method of the unipolar rectifier according to claim 1, wherein The calculating the predicted value based on the standard inductor current includes: Calculating the predicted value of the inductor current at the next moment; Constructing a cost function through the predicted value and the standard inductor current; Calculating the cost function value based on the switch control state and the cost function, and the cost function value has an associated relationship with the switch control state.

3. The control method of the unipolar rectifier according to claim 2, characterized in that, The setting the switch control state of the target system according to the predicted value includes: Extracting the target cost function value, where the target cost function value is the smallest cost function value; Outputting the target control state according to the target cost function value, where the target control state is the switch control state associated with the target cost function value; Setting the on-off state of the pre-stage switch according to the target control state.

4. A control device for a single-stage rectifier, characterized in that, Including a target system and an algorithm control system, the target system includes a power supply network, a single-stage rectifier, a buck-boost converter, and a load, and the algorithm control system is configured to: Detecting the target load voltage of the load; Calculating the voltage difference between the target load voltage and the standard load voltage; Inputting the voltage difference into a proportional-integral controller to obtain a standard grid current; The obtaining the standard grid current includes: Obtaining the adjustment coefficients of the proportional-integral controller, where the adjustment coefficients include a proportional adjustment coefficient and an integral adjustment coefficient; calculating the amplitude adjustment amount according to the adjustment coefficients and the voltage difference; Obtaining the grid current phase angle, where the grid current phase angle is obtained by sampling the grid voltage of the power supply network by a phase-locked loop module; Calculating the standard grid current through the grid current phase angle and the amplitude adjustment amount; The calculating the amplitude adjustment amount according to the adjustment coefficients and the voltage difference includes: Calculating the first product of the proportional adjustment coefficient and the voltage difference; Calculating the integral value of the voltage difference with respect to time; Calculating the second product of the integral adjustment coefficient and the integral value; Calculating the amplitude adjustment amount according to the sum value of the first product and the second product; The calculating the standard grid current through the grid current phase angle and the amplitude adjustment amount includes: Calculating the third product of the grid current phase angle and time; Calculating the sine value of the third product; Calculating the standard grid current according to the product of the sine value and the third product; Detecting the target grid current of the power supply network; Calculating the current difference between the target grid current and the standard grid current; Inputting the current difference into a proportional-resonant controller to obtain a standard inductor current; The obtaining the standard inductor current includes: Obtaining the control resonance and control frequency of the proportional-resonant controller, where the control resonance includes proportional resonance and integral resonance, and the control frequency includes resonance frequency and cut-off frequency; Constructing a transfer function according to the control resonance, the control frequency, and the grid current phase angle, where the grid current phase angle is obtained by sampling the grid voltage of the power supply network by a phase-locked loop module; Calculating the standard inductor current through the transfer function; Constructing the transfer function according to the following formula: wherein, kpr is the proportional resonance, kr is the resonance gain, ωc is the resonance frequency, ωr is the cut-off frequency, s is the complex frequency variable in the frequency domain and is the differential operator of time t; calculating a predicted value based on the standard inductor current, and setting a switching control state of the target system according to the predicted value; the predicted value is calculated by a finite control set model predictive control module based on the standard inductor current; the buck-boost converter includes a front-stage switch, the front-stage switch includes a first switch, a second switch, a third switch and a fourth switch, the single-stage rectifier includes a rear-stage switch, and the rear-stage switch includes a fifth switch and a sixth switch; the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch each include 2 on-off states, and the on-off states include an on state and an off state; the target system is configured with at least 3 switching control states, and the on-off states of the front-stage switch are different in different switching control states.

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