An ac-dc energy conversion system cooperative optimization regulation method and system

Abstract

The present application belongs to the technical field of AC-DC hybrid micro-grid regulation, in order to solve the problem that the existing AC-DC energy conversion system regulation cannot adapt to the dynamic change of load, a kind of AC-DC energy conversion system collaborative optimization regulation method and system are provided, the six-segment space vector modulation strategy of zero vector in advance is used for AC side matrix variable unit, square wave modulation strategy is used for DC side full-bridge variable unit;The phase shift angle between the output voltage of the AC side matrix variable unit and the DC side full-bridge variable unit is dynamically adjusted;Among them, in each control cycle, if the absolute error of the current AC side current is greater than the preset dead zone error, the adaptive update step is dynamically calculated according to the absolute error of the current AC side current, and the disturbance direction is determined based on the size of the trial modulus error and the absolute error of the current AC side current, if the disturbance direction is wrong, the step is updated, which can effectively suppress the AC side current harmonic and improve the power quality.

Description

Technical Field

[0001] This invention belongs to the technical field of AC / DC hybrid microgrid regulation, and particularly relates to a collaborative optimization regulation method and system for AC / DC energy conversion systems. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Whether it's bidirectional charging systems for electric vehicles, energy storage converters, solid-state transformers, or data center power supplies, all require efficient bidirectional conversion between AC and DC energy. As modern industry places increasingly stringent demands on the size, efficiency, and stability of high-end equipment, these AC / DC energy conversion systems demand high power density and high power quality on both the AC and DC sides.

[0004] The single-stage three-phase dual active bridge matrix converter topology, eliminating the need for the large-capacity DC bus capacitor found in traditional two-stage "AC / DC + DC / DC" topologies, offers significant advantages such as high power density and reliability, and is gradually becoming a hot topic in current research and engineering applications. However, the single-stage topology eliminates the large-capacity DC bus capacitor, which provides decoupling and buffering, leading to deep coupling of transient disturbances between the AC and DC sides, increasing the difficulty of coordinated power quality control on both sides. In conventional control strategies, the AC-side matrix converter unit and the DC-side full-bridge converter unit typically employ space vector modulation and square wave modulation strategies, respectively, while the phase shift angle between the output voltages of the two converter units is fixed and cannot adapt to dynamic load changes. To improve power quality, optimization search algorithms are often introduced to dynamically adjust the phase shift angle. However, traditional optimization search algorithms usually require multiple sampling points and complex derivative calculations, resulting in a large computational load and making it difficult to guarantee the real-time performance and stability of the system's closed-loop control. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a collaborative optimization control method and system for AC / DC energy conversion systems. By dynamically controlling the phase shift angle between the output voltages of the AC-side matrix converter and the DC-side full-bridge converter, AC-side current harmonics can be effectively suppressed, thereby improving power quality.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a collaborative optimization control method for an AC / DC power conversion system, applied to an AC / DC power conversion system, the AC / DC power conversion system comprising an AC-side matrix converter unit, a high-frequency isolation transformer, and a DC-side full-bridge converter unit, the control method comprising: The AC-side matrix transformation unit adopts a six-segment space vector modulation strategy with zero vector first, and the DC-side full-bridge transformation unit adopts a square wave modulation strategy. By dynamically adjusting the phase shift angle between the output voltages of the AC-side matrix converter and the DC-side full-bridge converter, bidirectional energy transfer is achieved. In each control cycle, an adaptive step size is dynamically calculated based on the absolute error of the current AC-side current, and the disturbance direction is determined based on the magnitude of the trial magnitude error and the absolute error of the current AC-side current. Based on the calculated adaptive step size, the current phase shift angle is updated with the goal of keeping the AC-side current magnitude constant.

[0007] Secondly, the present invention provides a collaborative optimization and control system for an AC / DC power conversion system, applied to an AC / DC power conversion system, wherein the AC / DC power conversion system includes an array converter unit, a high-frequency isolation transformer, and a DC-side full-bridge converter unit, and the control system includes: The strategy module is configured to: employ a six-segment space vector modulation strategy with zero vector first for the AC-side matrix transformation unit, and employ a square wave modulation strategy for the DC-side full-bridge transformation unit; The adjustment module is configured to achieve bidirectional energy transfer by dynamically adjusting the phase shift angle between the output voltages of the AC-side matrix converter and the DC-side full-bridge converter. Specifically, within each control cycle, an adaptive step size is dynamically calculated based on the absolute error of the current AC-side current, and the disturbance direction is determined based on the magnitude of the trial magnitude error and the absolute error of the current AC-side current. The current phase shift angle is updated based on the calculated adaptive step size, with the goal of keeping the AC-side current magnitude constant.

[0008] The above one or more technical solutions have the following beneficial effects: In this invention, a six-segment space vector modulation strategy with zero vector first is adopted for the AC-side matrix converter unit, and a square wave modulation strategy is adopted for the DC-side full-bridge converter unit. In each control cycle, the adaptive step size is dynamically calculated based on the absolute error of the current AC-side current, and the disturbance direction is determined based on the magnitude of the trial magnitude error and the absolute error of the current AC-side current. According to the adaptive step size, the current phase shift angle is updated with the goal of keeping the AC-side current magnitude constant. By dynamically adjusting the phase shift angle between the output voltages of the AC-side matrix converter unit and the DC-side full-bridge converter unit, AC-side current harmonics can be effectively suppressed, and power quality can be improved.

[0009] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0010] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0011] Figure 1 This is the topology of a single-stage three-phase dual active bridge matrix converter in an embodiment of the present invention; Figure 2 This is a schematic diagram of the sector division of the AC side matrix transformation unit in an embodiment of the present invention; Figure 3 This is a schematic diagram of bilateral coordinated regulation in an embodiment of the present invention; Figure 4 This is a schematic diagram of the optimized three-phase current steady-state waveform in an embodiment of the present invention; Figure 5 This is a flowchart of the variable step-size single-step perturbation observation method in an embodiment of the present invention; Figure 6 This is a schematic diagram of the optimized three-phase current steady-state waveform in an embodiment of the present invention; Figure 7 This is a schematic diagram of the optimization trajectory of the control algorithm in an embodiment of the present invention; Figure 8 This is a schematic diagram comparing the modulus values ​​before and after optimization with the baseline modulus values ​​in an embodiment of the present invention; Figure 9 This is a schematic diagram of error fluctuation before and after optimization in an embodiment of the present invention. Detailed Implementation

[0012] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0013] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0014] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0015] Example 1 This embodiment discloses a collaborative optimization and control method for AC / DC energy conversion systems. The AC / DC energy conversion system includes an AC-side matrix converter unit, a high-frequency isolation transformer, and a DC-side full-bridge converter unit. This device and method are mainly applied to bidirectional AC / DC energy conversion or flow scenarios, and are particularly suitable for high-end energy conversion equipment such as electric vehicle bidirectional charging systems (V2G), energy storage converters (PCS), solid-state transformers (SST), and data center power supplies.

[0016] In this embodiment, a six-segment space vector modulation strategy with zero vector first is adopted at the AC-side matrix conversion unit of the energy conversion system, and a square wave modulation strategy is adopted at the DC-side full-bridge conversion unit. Within each control cycle, the digital control unit acquires the current AC-side current vector angle and the optimal phase shift angle of the previous cycle, and calculates the absolute error between the actual current magnitude and the system reference magnitude. A probe increment is superimposed on the optimal phase shift angle of the previous cycle to calculate the trial magnitude error. By comparing the relative magnitudes of the absolute error, the trial magnitude error, and the preset tolerance threshold, the adaptive update step size is dynamically calculated, and the optimization direction is determined, completing the adaptive update of the phase shift angle. The updated phase shift angle is numerically limited and truncated before being output to the PWM generator and stored as the initial value for the next cycle. This invention effectively maintains a constant AC-side current magnitude, effectively reduces AC-side current harmonics and DC-side current ripple, and has low computational overhead, effectively ensuring system real-time performance.

[0017] like Figure 1 As shown in the figure, this embodiment provides a three-phase / single-phase dual active bridge matrix converter topology, which includes an AC-side matrix converter unit composed of an array matrix of multiple bidirectional power switches, a high-frequency isolation transformer unit, and a DC-side full-bridge converter unit composed of multiple active switches. The AC-side matrix converter unit and the DC-side full-bridge converter unit complete energy transfer through the high-frequency isolation transformer unit. The AC-side matrix converter unit and the DC-side full-bridge converter unit have the characteristics of a dual active bridge, meaning that both sides of the high-frequency isolation transformer can be equivalent to high-frequency alternating voltage sources. Figure 1 middle, , , Represents the three-phase voltage on the grid side. , , and , , These represent the grid-side filter inductor and filter capacitor, respectively. , , , , , , , , , , , These represent the switching transistors that constitute the AC-side matrix transformation unit. This represents the leakage inductance of a high-frequency transformer, where n:1 represents the turns ratio of the high-frequency transformer. and This represents the voltage across the leakage inductance of the transformer. This represents the output voltage of the full-bridge converter at the high-frequency transformer. , , , This represents the switching transistor at the full-bridge converter unit. and These represent the DC-side filter capacitor and filter inductor, respectively. Represents DC voltage.

[0018] Step 1: Bilateral modulation coordination.

[0019] A six-segment space vector modulation strategy with zero vector first is adopted at the AC-side matrix converter unit, and a square wave modulation strategy is adopted at the DC-side full-bridge converter unit. Bidirectional energy transfer is achieved by dynamically adjusting the phase shift angle between the output voltages of the AC-side matrix converter unit and the DC-side full-bridge converter unit.

[0020] In the modulation of the positive and negative half-cycles, this embodiment designs the control strategy at the AC side matrix transformation unit as a six-segment system. During the positive half-cycle, the zero vector is positioned at the front end of the effective vector corresponding to the smaller instantaneous voltage value, while during the negative half-cycle, the zero vector is positioned at the front end of the effective vector corresponding to the larger instantaneous voltage value. The entire vector space is divided into 12 equal parts, with the angle (-30°, 0°) corresponding to the first sector, (0°, 30°) corresponding to the second sector, and so on. The specific sector division is as follows: Figure 2 As shown. Within each sector, the voltage synthesis sequence is: zero voltage - small voltage with positive amplitude - large voltage with positive amplitude - zero voltage - large voltage with negative amplitude - small voltage with negative amplitude.

[0021] Figure 2 middle, - Represents the effective vector. - Represents the zero vector. - This represents the available effective vector during the positive half-switching cycle. - This represents the available effective vector during the negative half-switching cycle. θ represents the current vector, and θ represents the angle of the current vector.

[0022] Taking the first sector under rectified conditions as an example, the voltage synthesis sequence during the entire switching cycle is as follows: V aa -V ac - V ab -V aa -V ba-V ca ,like Figure 3 As shown.

[0023] Under this modulation sequence, the duty cycle of the large voltage vector is set to d x The duty cycle of the small voltage vector is set to d y The duty cycle of the zero voltage vector is set to d 0, its calculation expressions are as follows: ; in, m Represents the modulation ratio. θ Represents the angle of the current vector.

[0024] The DC-side full-bridge converter unit employs a square wave modulation strategy with a 50% duty cycle. For example... Figure 3 As shown, an amplitude of + is generated during the positive half-switching cycle. U o The voltage generates an amplitude of - during the negative half-switching cycle. U o The voltage is controlled such that the output voltage phase of the DC-side full-bridge converter lags behind the voltage phase of the AC-side matrix converter, thus enabling energy transfer from the AC side to the DC side.

[0025] Without the optimization algorithm of this embodiment, the expression for the corresponding AC side current is: ; In the above formula, m Represents the system modulation ratio. st This represents the normalized phase shift angle, ranging from (0.01, 0.5). Specifically, when... st When the phase ratio is 0.1, the output voltage phase of the DC-side full-bridge converter unit lags behind the voltage phase of the AC-side matrix converter unit by 36°. θ Represents the angle of the current vector.

[0026] like Figure 4 As shown, when the modulation ratio is 0.6 and the fixed phase shift angle is 0.2, the magnitude of the AC current changes dynamically with time, and there are a large number of harmonics in the three-phase current at the grid (THD is 6.45%). It can be seen that when the phase shift angle between the AC and DC sides is fixed, the magnitude of the AC current will generate periodic nonlinear pulsations as the vector angle changes dynamically, thereby introducing a large number of high-frequency harmonic components into the AC side, resulting in a reduction in AC power quality. In addition, according to the law of conservation of energy, under the condition that the DC voltage remains constant, the instantaneous fluctuation of the AC current magnitude will be directly mapped to the instantaneous power fluctuation inside the conversion system, which will inevitably induce high-frequency current ripple in the DC current.

[0027] Step 2: Adaptive variable step size single-step perturbation optimization.

[0028] This embodiment proposes an adaptive variable step-size single-step perturbation optimization method to maintain a constant AC side current magnitude. At high switching frequencies (where the single-step vector angle change is very small, and the objective function can be approximated as a locally convex function), this method optimizes solely through algebraic recursion and logical comparison.

[0029] like Figure 5 As shown, within each control cycle of the digital control unit (such as a DSP), the following sub-steps are executed: Step 21: State sampling and benchmark evaluation.

[0030] Based on the optimal phase shift angle obtained in the previous control cycle Calculate the actual magnitude of the current AC side based on the current vector angle. : ; Where m represents the system modulation ratio. θ Represents the angle of the current vector; st This represents the normalized phase shift angle.

[0031] The actual modulus of the current communication side Compared with the system reference modulus Subtract the values ​​to obtain the absolute error of the current AC side. , =| - |;System reference modulus For the system in its initial state The AC side current magnitude is calculated at that time.

[0032] Step 22: Inject perturbation and forward observation.

[0033] Based on the current control quantity, i.e., the optimal phase shift angle of the previous control cycle, a preset detection increment is superimposed. To obtain the trial control quantity Based on the trial control amount Recalculate the trial modulus error Specifically, the control quantity will be tested. Substituting the angle of the current vector and the modulation ratio into the expression for the AC side current: The AC side current test modulus corresponding to the current test control quantity is obtained. The error of the trial modulus is obtained by subtracting the absolute value of the reference modulus from the trial modulus value. =| - |

[0034] Step 23: Logical decision and adaptive update.

[0035] (1) Dead zone determination: Determine the absolute error of the current AC side. Is it less than the preset tolerance threshold? If the absolute error on the current AC side Less than the preset tolerance threshold If the current control cycle does not update the control quantity, it is determined to have entered the dead zone to prevent steady-state oscillation; if the current absolute error on the AC side... Greater than or equal to the preset tolerance threshold Then proceed to the next step; (2) Step size calculation: Dynamically calculate the current adaptive step size. : = min( , k * ) ; In the formula, the preset proportionality coefficient k The value range is limited to 0.05 < k <0.15, used to dynamically coordinate the dynamic response speed and steady-state tracking accuracy of the system in the digital control cycle; This is the upper limit of the adaptive step size.

[0036] Its adaptive coordination mechanism is as follows: If the proportional coefficient k Selecting too large (e.g.) k >0.15), although the control quantity can achieve rapid approximation during transient transitions, it is prone to numerical overshoot and oscillation at the optimization target point or steady-state dead zone boundary due to excessively large step size, thus reducing power quality; conversely, if the proportional coefficient is lower, k Selecting too small (e.g.) k While a step size <0.05 can further ensure the steady-state accuracy after convergence, it can lead to excessive compression of the optimization step size in the initial stage, resulting in a longer dynamic adaptive response time for the optimization control trajectory, which cannot meet the timing requirements of UHF control interruption. Therefore, the proportional coefficient is... k Strictly controlled at 0.05 < k A value between 0.15 and 0.15 enables the system to achieve the best synergistic balance between dynamic response speed and steady-state ripple suppression.

[0037] (3) Directional decision: If < This indicates that the direction of the disturbance is correct. = s opt + stepact Update control quantity; if > This indicates that the direction of the disturbance is incorrect. = s opt - step act Update control variables; The updated control quantity for the current control cycle is the phase shift angle.

[0038] Since the ultimate optimization goal of this system is to minimize the absolute error of the AC side modulus (i.e., the tolerance range difference), forward observation is performed by artificially injecting small probe increments, which essentially evaluates the discrete gradient direction of the local error function. If the probe error decreases, it indicates that the current probe direction is guiding the system towards the error minimum point, so this direction is maintained and a dynamic step size is applied to continue advancing; if the probe error increases, it indicates that the error minimum point is located in the opposite direction, so the update step size is reversed. This decision mechanism determines the optimal approximation direction by comparing algebraic inequalities.

[0039] Step 24: Numerical limiting and status registration.

[0040] The new control quantity calculated in step 23 is forcibly limited to a preset safe physical range, such as [0.01, 0.5]. Then, the limited control quantity is output to the PWM generator as the optimal phase shift angle at the current moment, and the new phase shift angle is stored as the initial value for the next control cycle.

[0041] As a preferred implementation, the digital control unit can employ a microcontroller with an integrated trigonometric function accelerator (TMU) (e.g., the TI C2000 series F28379D chip). This microcontroller can perform a single sine, cosine, or square root operation within 1 to 3 clock cycles as a single hardware instruction. For complex nonlinear expressions involving polynomial multiplication and addition operations during the optimization process, this hardware acceleration mechanism, combined with compiler optimization, reduces the computational load on the central processing unit, ensuring that the variable step-size optimization algorithm can be executed in real time within the control cycle. Simultaneously, this single-step perturbation optimization mechanism avoids the step jumps of traditional offline mesh methods, resulting in a smoother optimal phase shift angle optimization trajectory.

[0042] This embodiment is based on the energy conservation mapping mechanism. By updating the current phase shift angle with the goal of keeping the AC side current magnitude constant, the AC side current magnitude is maintained in real time, eliminating the power pulsation source from the source and reducing the DC side current ripple. This not only helps to extend the service life of energy storage components (such as power batteries) but also improves the system reliability.

[0043] In this embodiment, based on the relative magnitudes of the absolute error and tolerance threshold difference at the current moment, it is determined whether to maintain the control quantity from the previous control cycle or to perform a first-order algebraic addition and subtraction recursive update based on the optimal phase shift angle (optimal control quantity) of the previous control cycle to obtain the optimal control quantity for the current cycle. At the underlying mathematical architecture level, high-frequency optimization control is thoroughly simplified to basic algebraic arithmetic operations, avoiding complex derivative calculations and global searches. Combined with a hardware acceleration unit, this algorithm reduces the system's dependence on underlying hardware specifications, enabling seamless portability to conventional DSP platforms to meet the demands of multi-task, high-real-time control. Simultaneously, through variable step-size adaptive design and dead-zone determination mechanism, it effectively suppresses steady-state oscillations, achieving both high dynamic response speed and high steady-state accuracy of closed-loop control with low computational overhead.

[0044] To verify the actual effect of this embodiment, a simulation model based on the above hardware architecture and control algorithm was built. The main parameters are: control frequency 20kHz, initial modulation ratio 0.6, and initial phase shift angle 0.2. Figures 6 to 9 The simulation results lead to the following conclusions.

[0045] Effectively improves AC power quality, such as Figure 6 As shown in the figure, after adopting the collaborative optimization control method proposed in this embodiment, the total harmonic distortion (THD) of the AC side current decreased from 6.45% to 0.7%, meeting the stringent grid connection standard requirements.

[0046] It achieves smooth optimization of the search trajectory, such as Figure 7 As shown, under the adaptive variable step size single-step perturbation algorithm, the optimal phase shift angle evolves smoothly over time. That is, during the steady-state following and dynamic adjustment process of the system, the trajectory does not exhibit obvious step jumps or high-frequency chattering, verifying the strong robustness and stability of the new method.

[0047] Effectively reduced DC-side current ripple. Figure 8 and Figure 9 Simulation results show that after adopting the optimized algorithm of this embodiment, the actual current magnitude on the AC side is effectively clamped to the vicinity of the reference magnitude. Further analysis based on the law of conservation of energy shows that the transient pulsation of the DC current is suppressed from the source, and the current ripple is reduced by about 88.61%.

[0048] Example 2 The purpose of this embodiment is to provide a collaborative optimization and control system for an AC / DC power conversion system, applied to an AC / DC power conversion system. The AC / DC power conversion system includes an array converter unit, a high-frequency isolation transformer, and a DC-side full-bridge converter unit. The control system includes: The strategy module is configured to achieve bidirectional energy transfer by dynamically adjusting the phase shift angle between the output voltages of the AC-side matrix converter and the DC-side full-bridge converter. Specifically, within each control cycle, an adaptive step size is dynamically calculated based on the absolute error of the current AC-side current, and the disturbance direction is determined based on the magnitude of the trial magnitude error and the absolute error of the current AC-side current. The current phase shift angle is then updated based on the calculated adaptive step size, with the goal of keeping the AC-side current magnitude constant.

[0049] In further embodiments, the following is also provided: An electronic device includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor. When executed by the processor, the computer instructions perform the method described in Embodiment 1. For brevity, further details are omitted here.

[0050] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0051] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0052] A computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in Embodiment 1.

[0053] The method in Embodiment 1 can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor. The software modules can reside in readily available storage media in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, a detailed description is not provided here.

[0054] A computer program product includes a computer program that, when executed by a processor, implements the method described in Embodiment 1.

[0055] The present invention also provides at least one computer program product tangibly stored on a non-transitory computer-readable storage medium. The computer program product includes computer-executable instructions, such as instructions included in program modules, which execute in a device on a target real or virtual processor to perform the processes / methods described above. Typically, program modules include routines, programs, libraries, objects, classes, components, data structures, etc., that perform specific tasks or implement specific abstract data types. In various embodiments, the functionality of program modules can be combined or divided among program modules as needed. The machine-executable instructions for the program modules can execute within a local or distributed device. In a distributed device, the program modules can reside in both local and remote storage media.

[0056] The computer program code used to implement the methods of the present invention may be written in one or more programming languages. This computer program code may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the computer or other programmable data processing device, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a computer, partially on a computer, as a stand-alone software package, partially on a computer and partially on a remote computer, or entirely on a remote computer or server.

[0057] In the context of this invention, computer program code or related data may be carried by any suitable carrier to enable a device, apparatus, or processor to perform the various processes and operations described above. Examples of carriers include signals, computer-readable media, and the like. Examples of signals may include electrical, optical, radio, sound, or other forms of propagation signals, such as carrier waves, infrared signals, etc.

[0058] Those skilled in the art will recognize that the units and algorithm steps described in conjunction with the embodiments herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0059] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A collaborative optimization control method for an AC / DC energy conversion system, characterized in that, The method is applied to an AC / DC power conversion system, which includes a matrix converter unit, a high-frequency isolation transformer, and a DC-side full-bridge converter unit. The control method includes: The AC-side matrix transformation unit adopts a six-segment space vector modulation strategy with zero vector first, and the DC-side full-bridge transformation unit adopts a square wave modulation strategy. By dynamically adjusting the phase shift angle between the output voltages of the AC-side matrix converter and the DC-side full-bridge converter, bidirectional energy transfer is achieved. In each control cycle, the adaptive step size is dynamically calculated based on the absolute error of the current AC-side current, and the disturbance direction is determined based on the magnitude of the trial magnitude error and the absolute error of the current AC-side current. Based on the calculated adaptive step size, the current phase shift angle is updated with the goal of keeping the AC-side current magnitude constant. The determination of the absolute error of the current AC side current is as follows: The current vector angle of the current control cycle is obtained in real time, and the actual magnitude of the current AC side current is calculated using the optimal phase shift angle of the previous control cycle. The absolute error of the current AC side current is obtained by subtracting the actual magnitude of the current AC side current from the system reference magnitude. The determination of the trial modulus error is specifically as follows: The optimal phase shift angle of the previous control cycle is added to the preset detection increment to obtain the trial phase shift angle; Based on the proposed phase shift angle, the corresponding proposed modulus error is calculated by combining the current current vector angle and modulation ratio. Determine the absolute error of the current AC side. Is it less than the preset tolerance threshold? If the absolute error on the current AC side Less than the preset tolerance threshold If the current control cycle does not update the control quantity, it is determined that the system has entered a dead zone to prevent steady-state oscillations. If the absolute error on the current AC side... Greater than or equal to the preset tolerance threshold Then proceed to the next step; Dynamically calculate the current adaptive step size : = min( , k * ) ； In the formula, the preset proportionality coefficient k The value range is limited to 0.05 < k <0.15, used to dynamically coordinate the dynamic response speed and steady-state tracking accuracy of the system in the digital control cycle; This is the upper limit of the adaptive step size; If the trial magnitude error is less than the absolute error of the current AC side current, the disturbance direction is correct, and the phase shift angle of the current control cycle is updated by the sum of the optimal phase shift angle and the adaptive step size of the previous control cycle; if the trial magnitude error is greater than the absolute error of the current AC side current, the disturbance direction is incorrect, and the phase shift angle of the current control cycle is updated by the difference between the optimal phase shift angle and the adaptive step size of the previous control cycle.

2. The method for coordinated optimization and control of an AC / DC energy conversion system as described in claim 1, characterized in that, The system reference modulus is the AC side current modulus calculated when the AC / DC energy conversion system is in its initial startup and operation state, corresponding to a grid angle of 0°.

3. The method for coordinated optimization and control of an AC / DC energy conversion system as described in claim 1, characterized in that, By controlling the output voltage phase of the DC-side full-bridge converter to lag behind the voltage phase of the AC-side matrix converter, energy can be transferred from the AC side to the DC side.

4. The method for coordinated optimization and control of an AC / DC energy conversion system as described in claim 1, characterized in that, If the absolute error of the current AC side current is not greater than the preset tolerance threshold, the phase shift angle will be updated within the current control cycle.

5. The method for coordinated optimization and control of an AC / DC energy conversion system as described in claim 1, characterized in that, If the absolute error of the current AC side current is less than the preset tolerance threshold, it is determined that the dead zone has been entered, and the phase shift angle will not be updated in the current control cycle.

6. A collaborative optimization control method for an AC / DC energy conversion system as described in any one of claims 1-5, characterized in that, Also includes: The updated phase shift angle is limited within a preset safe physical range, and the limited phase shift angle is taken as the optimal phase shift angle at the current moment.

7. A collaborative optimization control system for AC / DC energy conversion systems, characterized in that, This system is applied to an AC / DC power conversion system, which includes a matrix converter unit, a high-frequency isolation transformer, and a DC-side full-bridge converter unit. The control system includes: The strategy module is configured to: employ a six-segment space vector modulation strategy with zero vector first for the AC-side matrix transformation unit, and employ a square wave modulation strategy for the DC-side full-bridge transformation unit; The adjustment module is configured to achieve bidirectional energy transfer by dynamically adjusting the phase shift angle between the output voltages of the AC-side matrix converter and the DC-side full-bridge converter; wherein, in each control cycle, the adaptive step size is dynamically calculated based on the absolute error of the current AC-side current, and the disturbance direction is determined based on the magnitude of the trial magnitude error and the absolute error of the current AC-side current; and the current phase shift angle is updated based on the calculated adaptive step size with the goal of keeping the AC-side current magnitude constant. The determination of the absolute error of the current AC side current is as follows: The current vector angle of the current control cycle is obtained in real time, and the actual magnitude of the current AC side current is calculated using the optimal phase shift angle of the previous control cycle. The absolute error of the current AC side current is obtained by subtracting the actual magnitude of the current AC side current from the system reference magnitude. The determination of the trial modulus error is specifically as follows: The optimal phase shift angle of the previous control cycle is added to the preset detection increment to obtain the trial phase shift angle; Based on the proposed phase shift angle, the corresponding proposed modulus error is calculated by combining the current current vector angle and modulation ratio. Determine the absolute error of the current AC side. Is it less than the preset tolerance threshold? If the absolute error on the current AC side Less than the preset tolerance threshold If the current control cycle does not update the control quantity, it is determined that the system has entered a dead zone to prevent steady-state oscillations. If the absolute error on the current AC side... Greater than or equal to the preset tolerance threshold Then proceed to the next step; Dynamically calculate the current adaptive step size : = min( , k * ) ； In the formula, the preset proportionality coefficient k The value range is limited to 0.05 < k <0.15, used to dynamically coordinate the dynamic response speed and steady-state tracking accuracy of the system in the digital control cycle; This is the upper limit of the adaptive step size; If the trial magnitude error is less than the absolute error of the current AC side current, the disturbance direction is correct, and the phase shift angle of the current control cycle is updated by the sum of the optimal phase shift angle and the adaptive step size of the previous control cycle; if the trial magnitude error is greater than the absolute error of the current AC side current, the disturbance direction is incorrect, and the phase shift angle of the current control cycle is updated by the difference between the optimal phase shift angle and the adaptive step size of the previous control cycle.

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