Dynamic correction method for flyback transformer of micro photovoltaic single-phase bidirectional grid-connected inverter and inverter

Abstract

The invention discloses a dynamic correction method for a flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter and the inverter. The dynamic correction method comprises the following steps: respectively acquiring a set current of the flyback transformer and a sampling current of a primary side of the flyback transformer; calculating a current difference value based on the set current and the sampling current; if the current difference value is greater than a preset threshold value, performing reverse correction on an initial inductance value of the flyback transformer according to the sampling current and a historical correction value to obtain a corrected inductance value; constructing a turn-on time calculation model according to the set current, the corrected inductance value, the primary side voltage value and the transformer turn ratio, and calculating target turn-on time based on the turn-on time calculation model; and generating a correction signal according to the target turn-on time, and driving a switching device of the flyback transformer to act through the correction signal to control a working time sequence of the flyback transformer so as to realize dynamic correction of the flyback transformer. According to the invention, accurate calculation of the turn-on time can be ensured, stable soft switching performance is ensured, and soft switching failure is avoided.

Description

Technical Field

[0001] This invention relates to the field of inverter technology, and in particular to a dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter and the inverter itself. Background Technology

[0002] With the widespread application of distributed photovoltaic systems, micro grid-connected inverters have gradually become one of the core devices in the field of solar power generation. To meet the requirements of miniaturization, high efficiency and low cost, flyback topologies are often used as the front-stage DC-DC boost converters of micro photovoltaic single-phase bidirectional grid-connected inverters, and usually operate in quasi-resonant (QR) mode. By realizing soft switching of switching devices (such as ZVS), switching losses and electromagnetic interference are reduced.

[0003] In QR mode, precise control of the switching timings, such as the turn-on and turn-off times of the switching transistors, directly determines system performance. However, the parameter characteristics of flyback transformers pose significant challenges to timing control: on the one hand, parameters such as transformer inductance and turns ratio cannot be detected in real time during circuit operation and must be preset manually; on the other hand, due to factors such as manufacturing process and core material, transformer inductance varies considerably and dynamically changes with operating conditions such as temperature and current. Because transformer inductance values ​​are difficult to obtain accurately online and update in real time, significant deviations in switching timing calculations occur, easily leading to soft-switching failures, increased power losses, and even control instability. Summary of the Invention

[0004] This invention provides a dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter, aiming to solve the problem that the transformer inductance value of current micro grid-connected inverters is difficult to obtain accurately online and update in real time, resulting in significant deviations in switching timing calculations, which can easily lead to soft switching failures, increased power losses, and even control instability.

[0005] In a first aspect, embodiments of the present invention provide a dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter, the method comprising: The set current of the flyback transformer and the sampled current of the primary side of the flyback transformer are obtained respectively. The current difference value is calculated based on the set current and the sampled current; If the current difference value is greater than a preset threshold, the initial inductance value of the flyback transformer is reverse-corrected according to the sampled current and the historical correction value to obtain a corrected inductance value. A turn-on time calculation model is constructed based on the set current, the corrected inductance value, the primary voltage value, and the transformer turns ratio, and the target turn-on time is calculated based on the turn-on time calculation model. A correction signal is generated based on the target turn-on time, and the switching device of the flyback transformer is driven by the correction signal to control the working sequence of the flyback transformer in order to achieve dynamic correction of the flyback transformer.

[0006] Secondly, embodiments of the present invention also provide a miniature single-phase bidirectional grid-connected inverter, wherein the miniature single-phase bidirectional grid-connected inverter is configured with the dynamic correction method for the flyback transformer of the miniature photovoltaic single-phase bidirectional grid-connected inverter described in any of the above claims.

[0007] This invention provides a dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter and an inverter. The method includes: acquiring a set current of the flyback transformer and a sampled current on the primary side of the flyback transformer; calculating a current difference value based on the set current and the sampled current; if the current difference value is greater than a preset threshold, performing a reverse correction on the initial inductance value of the flyback transformer based on the sampled current and historical correction values ​​to obtain a corrected inductance value; constructing a turn-on time calculation model based on the set current, the corrected inductance value, the primary voltage value, and the transformer turns ratio, and calculating a target turn-on time based on the turn-on time calculation model; generating a correction signal based on the target turn-on time, and driving the switching devices of the flyback transformer to control the operating timing of the flyback transformer to achieve dynamic correction of the flyback transformer. This invention provides a method to dynamically correct inductor parameters by triggering a current difference value greater than a preset threshold. The initial inductance value is then corrected by setting the current, sampling the current, and using historical correction values ​​to eliminate individual errors and modeling deviations caused by dynamic changes in transformer inductance. This ensures accurate turn-on time calculation, stable soft-switching performance, and prevents soft-switching failure. Attached Figure Description

[0008] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a flowchart illustrating the dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the first sub-process of the dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the second sub-process of the dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of the third sub-process of the dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter provided in an embodiment of the present invention. Figure 5 This is a schematic diagram of the fourth sub-process of the dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter provided in an embodiment of the present invention. Figure 6 This is a schematic diagram of the fifth sub-process of the dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter provided in this embodiment of the invention. Detailed Implementation

[0010] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0011] It should be understood that, when used in this specification and the appended claims, the terms “comprising” and “including” indicate the presence of the described features, integrals, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, operations, elements, components and / or collections thereof.

[0012] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0013] Please see Figure 1 , Figure 1 This is a flowchart illustrating the dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter provided in this embodiment of the invention. This dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter can be applied to micro single-phase bidirectional grid-connected inverters to adjust the turn-on time of the flyback transformer to ensure stable soft-switching performance and avoid soft-switching failure. Figure 1 As shown, the method includes steps S110 to S160.

[0014] S110, respectively acquire the set current of the flyback transformer and the sampled current of the primary side of the flyback transformer.

[0015] In this embodiment of the invention, the set current can be the output current of the MPPT (Maximum Power Point Tracking) module of the photovoltaic system. The MPPT calculates the current value corresponding to the maximum output power under the current illumination conditions by tracking the voltage-current characteristics of the photovoltaic module. This current serves as the target current that the primary side of the flyback transformer needs to achieve (ensuring maximum utilization of photovoltaic energy). During data acquisition, the data can be transmitted in real-time through the communication interface (such as ADC or SPI) between the MPPT and the controller (such as an MCU). The update frequency of the set current is synchronized with the flyback converter's operating cycle (typically 10kHz~100kHz).

[0016] The primary-side sampling current refers to the primary-side current during the MOSFET conduction period of the flyback transformer. A current sensor (such as a Hall current sensor or a high-precision shunt resistor + operational amplifier) ​​can be connected in series with the primary side of the flyback transformer to monitor the primary-side current during MOSFET conduction in real time. The current signal output from the current sensor is then converted into a digital value by an ADC module and input to the controller. It is necessary to ensure that the sampling frequency is ≥1MHz (to meet the requirement of capturing rapid current changes) and the accuracy is ±1% (to avoid measurement errors affecting subsequent deviation calculations).

[0017] S120, calculate the current difference value based on the set current and the sampled current.

[0018] In this embodiment of the invention, the current difference value is used to quantify the deviation between the actual current and the target current, serving as the driving signal for inductor correction. That is, the current difference value is used to quantify the difference between the set current and the sampled current, and it can be calculated using the following formula: ΔI=I set -I actual Where ΔI is the current difference value, I set To set the current, I actual This is the sampling current.

[0019] If ΔI > 0, it indicates that the actual current is less than the set current, suggesting insufficient primary-side energy storage (possibly due to an undersized inductor or insufficient turn-on time). If ΔI < 0, it indicates that the actual current is greater than the set current, suggesting excessive primary-side energy storage (possibly due to an oversized inductor or excessively long turn-on time). Furthermore, after obtaining the current difference value, it can be filtered to remove high-frequency noise. For example, a first-order low-pass filter can be applied to the current difference value.

[0020] See Figure 2 In some embodiments, such as in the embodiments of the present invention, step S120 further includes steps S121-S122.

[0021] S121, acquire the set current and the sampled current; S122, calculate the difference between the set current and the sampled current to obtain the current difference value.

[0022] In this embodiment of the invention, if the current I is set... set =5A, sampling current I actual =4.9A, then ΔI=5A-4.9A=0.1A, that is, the current difference in the current cycle is 0.1A. A first-order low-pass filter can be applied to this 0.1A to smooth the current difference. For example, the filter can be applied using the following formula: ΔI1=α·ΔI current +(1-α)·ΔI last Where ΔI1 is the filtered current difference value, ΔI current The current difference value for the current cycle, ΔI last Let α be the current difference value of the previous cycle, and α be the filter coefficient. If α = 0.4, ΔI last =0.08A, then: ΔI1=0.4·0.1+0.6·0.08=0.088A That is, the current difference after filtering is 0.088A.

[0023] S130, if the current difference value is greater than a preset threshold, the initial inductance value of the flyback transformer is reverse-corrected according to the sampled current and the historical correction value to obtain a corrected inductance value.

[0024] In this embodiment of the invention, the preset threshold is an empirical value used to indicate the degree of deviation between the sampled current and the set current. For example, the preset threshold can be 5% of the set current (if the set current is 5A, then the preset current is 0.25A). When the current difference is greater than the preset threshold, it indicates that the sampled current deviates significantly from the set current, and the initial inductance value needs to be corrected. Specifically, the initial corrected inductance value can be calculated in reverse based on energy conservation and volt-second balance using real-time parameters under the current operating conditions, to quickly match the actual inductance requirements of the current operating state. After obtaining the initial corrected inductance value, the initial corrected inductance value and the historical corrected inductance value can be merged through weight allocation to avoid correction fluctuations caused by single sampling anomalies and ensure parameter stability. The historical corrected inductance value refers to the inductance correction value calculated in previous control cycles.

[0025] See Figure 3 In some embodiments, such as in the embodiments of the present invention, step S130 further includes steps S131-S132.

[0026] S131, calculate the initial corrected inductance value based on the set current, the sampled current, the transformer turns ratio, and the bus voltage; S132, calculate the corrected inductance value based on the historical correction value, the preset weighting coefficient, and the initial corrected inductance value.

[0027] In some embodiments, such as in the embodiments of the present invention, step S132 further includes the following: Obtain the formula for correcting the first preset inductance value; The initial corrected inductance value is calculated by substituting the set current, the sampled current, the transformer turns ratio, and the bus voltage into the first preset inductance value correction formula.

[0028] In some embodiments, such as in this embodiment of the invention, the step of substituting the set current, the sampled current, the transformer turns ratio, and the bus voltage into the first preset inductance value correction formula to calculate the initial corrected inductance value further includes the following: Obtain the second preset inductance value correction formula; The historical correction value, the preset weighting coefficient, and the initial correction inductance value are substituted into the second preset inductance value correction formula to calculate the correction inductance value.

[0029] In this embodiment of the invention, the initial corrected inductance value is a theoretical inductance value obtained by inversely solving the real-time parameters under the current operating conditions. The purpose is to quickly match the actual inductance requirements of the current operating state. The initial corrected inductance value can be calculated through the following process: Calculate the operating period T of the flyback transformer: T=T on +T off +T dead Among them, T on =Opening time, T off =Shutdown time, T dead =Dead time, all are real-time sampled values. For example, if the real-time sampled value is T on =10μs, T off =22μs, T dead =2μs, then T=10+22+2=34μs.

[0030] The initial corrected inductance value TL is calculated in reverse based on energy conservation: From the law of conservation of energy, we can obtain: Where TL is the initial corrected inductance value, I actualLet W be the sampling current, W be the power, and T be the duty cycle of the flyback transformer. Combining the characteristics of the flyback topology (primary-side energy storage ≈ secondary-side output energy, neglecting losses), the formula for correcting the first preset inductance value is derived as follows: Among them, V bus TN is the bus voltage, T is the transformer turns ratio, and I is the flyback transformer duty cycle. actual This is the sampling current.

[0031] After obtaining the initial corrected inductance value, the initial corrected inductance value and the historical corrected inductance value can be fused to obtain the corrected inductance value. For example, if the weight of the initial corrected inductance value is α, and α can be 0.7~0.9 (prioritizing real-time sampling under the current operating condition), then the weight of the historical corrected inductance value can be 1-α, and 1-α can be 0.1~0.3 (considering historical experience and avoiding noise interference from single sampling). For example, if α=0.8 (current data is primary, historical data is secondary), then 1-α=0.2. Then, the corrected inductance value is calculated using the second preset inductance value correction formula. TL0 = α × TL + (1 - α) × TL1 Where TL0 is the corrected inductance value, TL is the initial corrected inductance value, and TL1 is the historical corrected value.

[0032] After obtaining the corrected inductance value, it can be verified to avoid invalid corrections. Specifically, this can be verified using soft-switching conditions and volt-second balance.

[0033] Volt-second balance verification Substitute the corrected inductance value into the volt-second balance formula to obtain T. on Verify that the error of the volt-second balance formula is ≤5%. If the error exceeds the standard, the weighting coefficient α needs to be readjusted (e.g., α=0.75), and the corrected inductance value needs to be calculated again.

[0034] Soft-switching condition verification The corrected inductance value must meet soft-switching conditions, protection limits, and valley switching. Therefore, it is necessary to verify the resonant period Tm corresponding to the corrected inductance value to ensure the turn-on time T calculated subsequently. on If the switching window is not satisfied when the value falls to the bottom, the inductance value needs to be finely adjusted.

[0035] Finally, the corrected inductance value obtained in this study is stored as a historical correction value for use in the next correction calculation, forming a closed loop of real-time correction → historical data accumulation → iterative optimization. Meanwhile, the corrected inductance value remains fixed within the current work cycle to ensure the stability of the modeling and calculation.

[0036] S140, construct a turn-on time calculation model based on the set current, the corrected inductance value, the primary voltage value, and the transformer turns ratio, and calculate the target turn-on time based on the turn-on time calculation model.

[0037] In this embodiment of the invention, the activation time calculation model is used to calculate the target activation time, and its derivation process is as follows: The basic activation time can be calculated using the following formula: Among them, T on1 The base turn-on time, TL is the corrected inductance value, and I set To set the current, V pv This is the primary voltage value. Then, it is determined by T. on1 The volt-second balance formula yields the activation time calculation model: Among them, T on T is the initial activation time. dead For dead time, T 周期参考 This refers to the actual testing period of the previous working cycle. After obtaining the initial activation time, the initial activation time can be limited to obtain the target activation time.

[0038] See Figure 4 In some embodiments, such as in the embodiments of the present invention, step S140 further includes steps S141-S143.

[0039] S141, based on the principles of energy conservation and volt-second balance, a turn-on time calculation model is constructed using the set current, the corrected inductance value, the primary voltage value, and the transformer turns ratio; S142, calculate the initial activation time using the activation time calculation model; S143, the initial activation time is subjected to a limiting process to obtain the target activation time.

[0040] In this embodiment of the invention, the basic turn-on time can be calculated based on the energy conservation formula. Then, the equation of the basic turn-on time is substituted into the volt-second balance formula to obtain the turn-on time calculation model. Subsequently, the initial turn-on time can be calculated using the turn-on time calculation model. Finally, the target turn-on time can be obtained by limiting the initial turn-on time. The limiting process is used to set reasonable boundaries and precise clamping to ensure that the turn-on time of the switching device falls within the range of effective soft switching, device safety, and system stability. The limiting process can be performed based on principles such as energy conservation, resonant period, and dead zone constraints.

[0041] See Figure 5In some embodiments, such as in the embodiments of the present invention, step S143 further includes steps S1431-S1434.

[0042] S1431, obtain the maximum activation time and minimum activation time; S1432, if the initial activation time is greater than or equal to the maximum activation time, then the maximum activation time is taken as the target activation time; S1433, if the initial activation time is less than or equal to the minimum activation time, then the minimum activation time is taken as the target activation time; S1434, if the initial activation time is greater than the minimum activation time and less than the maximum activation time, then the initial activation time is taken as the target activation time.

[0043] In this embodiment of the invention, the boundaries of the maximum / minimum turn-on time are not fixed values, but are dynamically calculated based on soft switching constraints, energy conservation constraints, device physical constraints, and timing safety constraints to ensure that the boundaries are fully matched with the actual operating conditions of the system and the characteristics of the devices.

[0044] Maximum opening time T onmax T onmax This is the upper limit threshold for the activation time; exceeding it will lead to soft-switching failure and a surge in device losses. The calculation must simultaneously satisfy two core constraints, and the minimum of the two values ​​is ultimately taken: Constraint 1: Soft-switching resonance constraint Formula for upper limit constraint of soft switching: T onmax1 =0.4×Tm Among them, T onmax1 Tm is the upper limit of soft switching, and Tm is the resonant period.

[0045] Constraint 2: Device Physical Constraints Switching devices have a maximum withstand turn-on time, provided in the device datasheet and denoted as T. onmax2 .

[0046] Based on constraints 1 and 2, we have: T onmax =min(T onmax1 ,T onmax2 ) Minimum opening time T onmin Minimum opening time T onmin This is the lower limit threshold for the activation time. If it is lower than this, it will lead to insufficient energy storage and mis-activation of the switching transistor. The calculation must satisfy two core constraints simultaneously, and the maximum value of the two is taken in the end. Constraint 1: Energy conservation constraint T onmin1 The activation time must meet the system's minimum energy storage requirements (to avoid abnormal output power), based on the energy conservation formula.

[0047] Constraint 2: Timing safety constraint T onmin2 The activation time must be greater than the dead time plus redundancy (to avoid mis-activation by the switching transistor), that is: T onmin2 =T dead +1μs Among them, T dead The dead time is 1 μs, and the redundancy is 1 μs. From constraints 1 and 2, we have: T onmin= max(T onmin1 ,T onmin2 ) After obtaining the maximum and minimum activation times, the relationship between the initial activation time and the maximum and minimum activation times can be determined. If the initial activation time is between the minimum and maximum activation times, the initial activation time is taken as the target activation time. If the initial activation time is greater than or equal to the maximum activation time, the maximum activation time is taken as the target activation time. If the initial activation time is less than or equal to the minimum activation time, the minimum activation time is taken as the target activation time.

[0048] S150, a correction signal is generated according to the target turn-on time, and the switching device of the flyback transformer is driven by the correction signal to control the working sequence of the flyback transformer so as to achieve dynamic correction of the flyback transformer.

[0049] In this embodiment of the invention, the precisely calculated target turn-on time can be converted into a correction signal that can drive the switching device. By controlling the working timing (turn-on / turn-off / dead time) of the flyback transformer, the influence of inductor parameter error on soft-switching performance can be eliminated, and finally, dynamic correction of the transformer can be achieved.

[0050] See Figure 6 In some embodiments, such as in the embodiments of the present invention, step S150 further includes steps S151-S153.

[0051] S151, calculate the operating cycle of the flyback transformer based on the target turn-on time; S152, Calculate the PWM duty cycle based on the target turn-on time and the working cycle; S153, generate the correction signal according to the PWM duty cycle.

[0052] In this embodiment of the invention, the duty cycle is equal to the sum of the on-time, off-time, and dead time. After obtaining the target on-time, the off-time can be calculated based on the volt-second balance formula. The dead time is related to the corrected inductance value and can be calculated by the following formula: Where Tdead is the dead time, TL0 is the correction inductance value, and Cds is the DMOS junction capacitance (fixed value). The duty cycle is obtained by summing the target on-time, off-time, and dead time. Then, the PWM duty cycle is calculated based on the duty cycle, and a correction signal is generated based on this duty cycle. This correction signal is a drive signal that meets the PWM duty cycle requirements. After generation, it needs to be sent to the switching device (DMOS) of the flyback transformer to drive it to operate according to the target timing sequence, ultimately achieving dynamic compensation for inductance parameter errors.

[0053] For example, a PWM drive signal is sent to the DMOS switching device of the flyback transformer to control it: Conduction Phase: Duration = T ontarget (e.g., 8.3μs), the primary-side inductor stores energy to meet the energy requirements corresponding to the set current; Shutdown Phase: Duration = T off (e.g., 0.0786 μs), the primary-side energy storage is released to the bus via the secondary side (V). bus ), to achieve energy conversion; Dead Zone Phase: Duration = T dead (e.g., 3.5μs) to avoid mis-conduction between DMOS and freewheeling devices (document protection restrictions are a core requirement).

[0054] Through the above timing control, the turn-on time corresponding to the corrected inductance value is precisely matched with the soft-switching conditions, eliminating the timing deviation caused by the initial inductance error, ensuring that the DMOS operates in the valley switching state, the soft-switching performance is stable, and the system efficiency and control accuracy are improved.

[0055] The present invention also provides a miniature single-phase bidirectional grid-connected inverter, wherein the miniature single-phase bidirectional grid-connected inverter is configured with the dynamic correction method for the flyback transformer of the miniature photovoltaic single-phase bidirectional grid-connected inverter described in any of the above embodiments.

[0056] The dynamic correction method for the flyback transformer of the micro photovoltaic single-phase bidirectional grid-connected inverter of the present invention triggers dynamic correction of inductance parameters by the current difference value being greater than a preset threshold, and corrects the initial inductance value by setting the current, sampling the current and historical correction values ​​to eliminate individual errors of transformer inductance and modeling deviations caused by dynamic changes, ensuring accurate calculation of turn-on time, ensuring stable soft switching performance, and avoiding soft switching failure.

[0057] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0058] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Since these modifications and variations fall within the scope of the claims and their equivalents, this invention also intends to include these modifications and variations.

[0059] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A dynamic correction method for the flyback transformer of a micro photovoltaic single-phase bidirectional grid-connected inverter, characterized in that, The method includes: The set current of the flyback transformer and the sampled current of the primary side of the flyback transformer are obtained respectively. The current difference value is calculated based on the set current and the sampled current; If the current difference value is greater than a preset threshold, the initial inductance value of the flyback transformer is reverse-corrected according to the sampled current and the historical correction value to obtain a corrected inductance value. A turn-on time calculation model is constructed based on the set current, the corrected inductance value, the primary voltage value, and the transformer turns ratio, and the target turn-on time is calculated based on the turn-on time calculation model. A correction signal is generated based on the target turn-on time, and the switching device of the flyback transformer is driven by the correction signal to control the working sequence of the flyback transformer in order to achieve dynamic correction of the flyback transformer.

2. The method as described in claim 1, characterized in that, The step of calculating the current difference value based on the set current and the sampled current includes: Obtain the set current and the sampled current; The difference between the set current and the sampled current is calculated to obtain the current difference value.

3. The method as described in claim 1, characterized in that, The step of reversely correcting the initial inductance value of the flyback transformer based on the set current, the sampled current, and the historical correction value to obtain the corrected inductance value includes: The initial corrected inductance value is calculated based on the set current, the sampled current, the transformer turns ratio, and the bus voltage. The corrected inductance value is calculated based on the historical correction value, the preset weighting coefficient, and the initial corrected inductance value.

4. The method as described in claim 3, characterized in that, The step of calculating the initial corrected inductance value based on the set current, the sampled current, the transformer turns ratio, and the bus voltage includes: Obtain the formula for correcting the first preset inductance value; The initial corrected inductance value is calculated by substituting the set current, the sampled current, the transformer turns ratio, and the bus voltage into the first preset inductance value correction formula.

5. The method as described in claim 3, characterized in that, The step of calculating the corrected inductance value based on the historical corrected value, the preset weighting coefficient, and the initial corrected inductance value includes: Obtain the second preset inductance value correction formula; The historical correction value, the preset weighting coefficient, and the initial correction inductance value are substituted into the second preset inductance value correction formula to calculate the correction inductance value.

6. The method as described in claim 1, characterized in that, The step of constructing a turn-on time calculation model based on the set current, the corrected inductance value, the primary voltage value, and the transformer turns ratio, and calculating the target turn-on time based on the turn-on time calculation model, includes: Based on the principles of energy conservation and volt-second balance, a turn-on time calculation model is constructed using the set current, the corrected inductance value, the primary voltage value, and the transformer turns ratio. The initial activation time is calculated using the activation time calculation model. The initial activation time is limited to obtain the target activation time.

7. The method as described in claim 6, characterized in that, The step of limiting the initial activation time to obtain the target activation time includes: Get the maximum activation time and minimum activation time; If the initial activation time is greater than or equal to the maximum activation time, then the maximum activation time shall be used as the target activation time; If the initial activation time is less than or equal to the minimum activation time, then the minimum activation time shall be used as the target activation time; If the initial activation time is greater than the minimum activation time but less than the maximum activation time, then the initial activation time is taken as the target activation time.

8. The method as described in claim 1, characterized in that, The step of generating a correction signal based on the target activation time includes: Calculate the operating cycle of the flyback transformer based on the target turn-on time; Calculate the PWM duty cycle based on the target turn-on time and the working cycle; The correction signal is generated based on the PWM duty cycle.

9. The method as described in claim 1, characterized in that, The method further includes: If the current difference value is less than or equal to the preset threshold, the initial inductance value will not be corrected.

10. A miniature single-phase bidirectional grid-connected inverter, characterized in that, The micro single-phase bidirectional grid-connected inverter is configured with the dynamic correction method for the flyback transformer of the micro photovoltaic single-phase bidirectional grid-connected inverter as described in any one of claims 1-9.

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