H-bridge converter control method and system based on dynamic rotation high-low frequency module

Abstract

The application relates to the technical field of power electronic converter control, in particular to an H-bridge converter control method and system based on dynamic rotation of high-frequency and low-frequency modules. The method combines real-time collection of junction temperatures and switching losses of each H-bridge module; for each H-bridge module, a first absolute difference value of the current junction temperature and the current average junction temperature is calculated, and a second absolute difference value of the cumulative switching loss and the average cumulative switching loss is calculated; according to the first absolute difference value and the corresponding temperature weight coefficient, and the second absolute difference value and the corresponding power loss weight coefficient, the rotation index of each H-bridge module is determined; and according to the rotation index of each module, a corresponding pulse control signal is generated, the high-frequency module to be rotated is switched to a low-frequency module, and the low-frequency module to be rotated is switched to a high-frequency module. Under the premise of ensuring the quality of electric energy output, the method can balance switching loss and thermal stress and other problems, and significantly improve the loss balance and temperature consistency of the H-bridge converter.

Description

H-bridge converter control method and system based on dynamic high- and low-frequency switching modules Technical Field

[0001] This application relates to the field of power electronic converter control technology, and in particular to an H-bridge converter control method and system based on dynamically switching high and low frequency modules. Background Technology

[0002] With the rapid development of renewable energy power generation, distributed energy sources such as photovoltaics and wind power are gradually being connected to the grid on a large scale. This places higher demands on power electronic conversion technology. H-bridge converters, with their advantages of strong modularity and low harmonic content in output waveforms, have been widely favored in high-voltage and high-power applications. In practical applications, H-bridge converters typically contain multiple H-bridge modules, with the module responsible for harmonic optimization serving as the high-frequency module and the module responsible for the fundamental component output serving as the low-frequency module.

[0003] Traditional H-bridge converters employ control strategies such as carrier phase-shift modulation or nearest-level approximation modulation, often with a fixed allocation between high-frequency and low-frequency modules. While simple to implement, this fixed allocation method has significant drawbacks. First, high-frequency modules experience more frequent switching, resulting in significantly higher switching losses and junction temperatures compared to low-frequency modules. Under long-term operation, the power devices in high-frequency modules age faster, and the heat dissipation area where high-frequency modules are located may experience localized overheating, exacerbating thermal stress concentration and potentially triggering shutdown. Second, current technology only passively switches when a particular H-bridge module experiences excessive switching losses or junction temperatures; this lag in response makes precise active adjustment difficult. Furthermore, under light loads or variable operating conditions, it is difficult to maintain optimal performance when load fluctuations or temperature changes occur, resulting in low conversion efficiency and failing to meet the requirements of practical applications.

[0004] To address the aforementioned issues, existing technologies employ a periodic switching scheme for high- and low-frequency modules, attempting to balance switching losses and module junction temperatures through regular switching. However, this static switching strategy, based solely on fixed time intervals, fails to consider the actual operating conditions of the H-bridge converter, still exhibiting the problem of unreasonable switching timing. It cannot truly achieve a balance between harmonic optimization and switching loss equalization, and is therefore not an ideal high- and low-frequency switching method. Thus, a control method capable of dynamically adjusting the allocation of high- and low-frequency modules based on actual operating conditions is urgently needed to achieve unified optimization of switching loss equalization and thermal stress equalization. Summary of the Invention

[0005] Therefore, it is necessary to provide a control method and system for H-bridge converters based on dynamically rotating high and low frequency modules. While ensuring the quality of power output, this method can also address issues such as switching loss balance and thermal stress balance, thereby significantly improving the loss balance and temperature consistency of the H-bridge converter.

[0006] The above-mentioned objective of this application is achieved through the following technical solution.

[0007] On one hand, the H-bridge converter control method based on dynamically rotating high and low frequency modules includes the following steps:

[0008] For each H-bridge module, real-time junction temperature data is collected based on a preset junction temperature sampling frequency. The effective junction temperature value of each module is determined based on the real-time junction temperature data. Instantaneous switching loss data is collected based on a preset power loss sampling frequency. The cumulative switching loss within a preset statistical time period is calculated.

[0009] Obtain the total number of H-bridge modules in the entire H-bridge converter, calculate the average junction temperature of all H-bridge modules based on the effective junction temperature value, and calculate the average cumulative switching loss of all H-bridge modules based on the cumulative switching loss.

[0010] For each H-bridge module, the rotation index of the H-bridge module is calculated based on the first absolute difference between the effective junction temperature and the average junction temperature, and the second absolute difference between the cumulative switching loss and the average cumulative switching loss, combined with the preset temperature weighting coefficient and power loss weighting coefficient.

[0011] H-bridge modules whose rotation index is greater than a first preset threshold are marked as high-frequency modules to be rotated, and H-bridge modules whose rotation index is less than a second preset threshold are marked as low-frequency modules to be rotated.

[0012] Based on the rotation index of each H-bridge module, a pulse control signal of the corresponding frequency is sent to adjust the switching frequency of the high-frequency module to be rotated to low-frequency mode and the switching frequency of the low-frequency module to be rotated to high-frequency mode.

[0013] In an optional embodiment, the method for obtaining the rotation index includes:

[0014] For each H-bridge module, a first absolute difference is calculated based on the effective junction temperature and the average junction temperature, and the product of the first absolute difference and the temperature weighting coefficient is used as the temperature equalization term.

[0015] For each H-bridge module, a second absolute difference is calculated based on the cumulative switching loss and the average cumulative switching loss. The product of the second absolute difference and the power loss weighting coefficient is used as the power loss balancing term. The sum of the temperature weighting coefficient and the power loss weighting coefficient is 1.

[0016] The arithmetic sum of the temperature equalization term and the power loss equalization term is used as the rotation index.

[0017] In an optional embodiment, the temperature weighting coefficient ranges from 0.3 to 0.7, and the power loss weighting coefficient ranges from 0.3 to 0.7.

[0018] In an optional embodiment, the first preset threshold ranges from +0.4 to +0.6, and the second preset threshold ranges from -0.6 to -0.4.

[0019] In an optional embodiment, determining the effective junction temperature value of each module based on the real-time junction temperature data includes:

[0020] For each H-bridge module, the average junction temperature data within a preset statistical time period of each module is calculated as the effective junction temperature value of the module; or, the highest junction temperature data within a preset statistical time period of each module is used as the effective junction temperature value of the module.

[0021] In an optional embodiment, the cumulative switching loss is obtained by integrating or summing the instantaneous switching loss data over a preset statistical time period.

[0022] In an optional embodiment, during the switching between high-frequency and low-frequency modules,

[0023] If the number of high-frequency modules to be rotated is equal to the number of low-frequency modules to be rotated, then the switching frequency of all high-frequency modules to be rotated is directly adjusted to low-frequency mode, and the switching frequency of all low-frequency modules to be rotated is adjusted to high-frequency mode.

[0024] If the number of high-frequency modules to be rotated is less than the number of low-frequency modules to be rotated, the low-frequency modules to be rotated are sorted in ascending order based on the value of the rotation index. Based on the number of high-frequency modules to be rotated, a number of low-frequency modules with the highest ranking are selected, and the switching frequency of such low-frequency modules is adjusted to high-frequency mode first. The switching frequency of all high-frequency modules to be rotated is adjusted to low-frequency mode.

[0025] If the number of high-frequency modules to be rotated is greater than the number of low-frequency modules to be rotated, the high-frequency modules to be rotated are sorted in descending order based on the value of the rotation index. Based on the number of low-frequency modules to be rotated, a number of high-frequency modules with the highest ranking are selected, and the switching frequency of such high-frequency modules is adjusted to low-frequency mode first. The switching frequency of all low-frequency modules to be rotated is adjusted to high-frequency mode.

[0026] In an optional embodiment, the preset power loss sampling frequency is not less than 10kHz.

[0027] In an optional embodiment, the method further includes the following steps:

[0028] The output current and output voltage of the entire H-bridge converter are collected in real time. The actual output power of the H-bridge converter is calculated based on the output current and output voltage. The power difference value between the actual output power and the preset output power is obtained. The duty cycle of the pulse control signal is adjusted according to the power difference value.

[0029] On the other hand, this application also provides an H-bridge converter control system, wherein the H-bridge converter includes multiple H-bridge modules;

[0030] A real-time monitoring module is connected to each of the H-bridge modules and is used to collect the operating parameters of each H-bridge module in real time. The operating parameters include at least real-time junction temperature data and switching loss data.

[0031] The controller, electrically connected to the real-time monitoring module, is used to receive the operating parameters and execute the H-bridge converter control method based on dynamically rotating high and low frequency modules as described in the above embodiment, generating and outputting pulse control signals for controlling the operation of each H-bridge module.

[0032] The present invention has the following beneficial effects:

[0033] This invention can collect junction temperature and switching loss data of each H-bridge module in real time, and comprehensively evaluate the module switching timing by combining the two factors of temperature and switching loss. It determines the rotation index and makes dynamic rotation decisions, effectively avoiding localized overheating or excessive switching losses in a particular module. This dynamic rotation control method can balance the switching losses and temperature distribution of each H-bridge module in real time, ensuring stable operation of the H-bridge converter under complex conditions. It dynamically adjusts the module operating frequency to optimize heat distribution, preventing certain modules from operating at high frequencies for extended periods, thus making the aging rate of each H-bridge module more uniform and significantly extending the lifespan of power devices.

[0034] This invention also achieves an active adjustment mechanism through a dual-threshold design of rotating indicators. Compared with traditional passive response methods, it can proactively adjust before problems occur, greatly improving the reliability and stability of the system. Furthermore, through the flexible configuration of temperature and power loss weighting coefficients, it can be specifically optimized according to the needs of different application scenarios, enhancing the applicability and flexibility of the method.

[0035] This invention further optimizes system performance through intelligent rotation strategy and power feedback adjustment function when the quantity is mismatched, realizes multi-objective collaborative optimization, takes into account multiple key indicators such as power quality, power loss balance and thermal stress balance, significantly improves the comprehensive performance of H-bridge converter, and has high engineering practical value. Attached Figure Description

[0036] Figure 1 is a flowchart illustrating the H-bridge converter control method of the present invention.

[0037] Figure 2 is a topology diagram of the three-phase n-stage H-bridge cascaded converter of the present invention.

[0038] Figure 3 is a dynamic rotation decision logic diagram of the present invention. Detailed Implementation

[0039] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, a detailed description of specific embodiments of this application is provided below. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0040] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0041] Unless otherwise defined, 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 application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0042] In existing technologies, H-bridge converters include several power modules, referred to as H-bridge modules, including high-frequency and low-frequency modules. The high-frequency module is used for harmonic optimization to improve waveform quality, while the low-frequency module is responsible for the fundamental component output. In traditional control, the switching devices of the high-frequency module always operate in high-frequency mode, and the switching devices of the low-frequency module always operate in low-frequency mode. After the H-bridge converter has been operating for a period of time, the high-frequency module is switched to low-frequency mode, and vice versa, in a fixed cycle. Before the next cycle, the high-frequency module may overheat locally, exacerbating thermal stress concentration and affecting system reliability.

[0043] Traditional H-bridge converters employ a control strategy that uses a fixed allocation of high and low frequency modules, which suffers from technical problems such as inconsistent aging rates of power devices, thermal stress concentration, delayed response mechanisms, and poor adaptability to varying operating conditions. To address these issues, this invention provides an H-bridge converter control method based on dynamically rotating high and low frequency modules. Based on real-time junction temperature data and switching loss data, and considering a "rotation index" that integrates the deviation between module junction temperature and switching power loss, the method achieves dynamic and predictive proactive switching of module operating frequencies. This allows the H-bridge converter to balance harmonic optimization, switching loss equalization, and thermal stress equalization while ensuring power output quality, effectively balancing the switching losses and temperature distribution of each module.

[0044] Figures 1 and 3 illustrate an H-bridge converter control method based on dynamically rotating high- and low-frequency modules according to an embodiment of this application, as well as the corresponding decision logic. In this embodiment, as shown in Figure 2, the H-bridge converter is a three-phase n-stage cascaded H-bridge converter. Each phase consists of n voltage-source H-bridge inverter modules connected in series (n is the number of H-bridge inverter modules connected in series in each phase of the converter, and the H-bridge inverter module is simply referred to as an H-bridge module). Each H-bridge inverter module consists of four insulated-gate bipolar transistors (IGBTs) and corresponding anti-parallel diodes.

[0045] The H-bridge converter control method based on dynamically rotating high and low frequency modules includes the following steps:

[0046] S1: For each H-bridge module, real-time junction temperature data is collected based on a preset junction temperature sampling frequency. The effective value of the junction temperature is determined based on the real-time junction temperature data. Instantaneous switching loss data is collected based on a preset power loss sampling frequency. The cumulative switching loss within a preset statistical time period is calculated.

[0047] Referring to Figure 2, the H-bridge module is an H-bridge inverter module. If the preset junction temperature sampling frequency is too low, it cannot accurately reflect the actual junction temperature of each H-bridge module, resulting in inaccurate calculations of the effective junction temperature and average junction temperature. This leads to deviations in the switching performance indicators and prevents timely switching between high and low frequency modules. A higher preset junction temperature sampling frequency indicates a shorter sampling time interval, which better reflects the junction temperature of the H-bridge module at various time points. The calculated effective junction temperature and average junction temperature are more accurate, resulting in smaller deviations in the determined switching performance indicators. This allows for timely switching between high and low frequency modules, which is beneficial for balancing switching losses and thermal stress. Therefore, in this embodiment, a suitable value needs to be determined for the preset junction temperature sampling frequency. Through multiple experiments, the inventors found that setting the preset junction temperature sampling frequency to be greater than or equal to 10kHz is optimal. A sampling frequency of 10kHz means collecting 10,000 data points per second, or one data point every 0.1 milliseconds, ensuring accurate capture of the dynamic characteristics of the H-bridge inverter module. In a preferred embodiment, the preset junction temperature sampling frequency can be 10kHz, 12kHz, 15kHz, or other values.

[0048] The preset power loss sampling frequency can be higher than the preset junction temperature sampling frequency, for example, it can be 12kHz, 13kHz, 15kHz, 16kHz or other values ​​above 10kHz.

[0049] Traditional fixed-allocation high- and low-frequency module rotation strategies often consider only a single factor, such as module junction temperature or switching losses, without comprehensively evaluating multiple factors. This often results in neglecting one aspect for another, failing to balance thermal stress and switching loss. In this embodiment, the junction temperature and switching losses of each H-bridge inverter module are collected in real time, and dynamic rotation decisions are made based on real-time operating status evaluation, achieving proactive balancing of switching losses and thermal stress among the various H-bridge inverter modules.

[0050] The method for acquiring module junction temperature is as follows: deploy corresponding temperature sensors in the area where each H-bridge inverter module is located to acquire module junction temperature in real time, and then transmit the real-time junction temperature data acquired by the temperature sensors to the controller.

[0051] The method for collecting module switching losses is as follows: a switching loss detection unit is installed on the connection lines of each H-bridge inverter module to collect the module switching losses in real time and transmit the real-time switching loss data to the controller. The specific form of the switching loss detection unit is not limited.

[0052] S2: Obtain the total number of H-bridge modules in the entire H-bridge converter, calculate the average junction temperature of all H-bridge modules based on the effective junction temperature value, and calculate the average cumulative switching loss of all H-bridge modules based on the cumulative switching loss.

[0053] In this embodiment, the total number of H-bridge modules is the same as the total number of H-bridge inverter modules in the H-bridge converter. If each phase consists of n H-bridge inverter modules connected in series, and the three phases are connected in parallel, the total number of H-bridge modules is 3n. The total number of H-bridge modules in the entire H-bridge converter is obtained, and combined with the real-time junction temperature data of each H-bridge module, the average junction temperature of all H-bridge modules is calculated.

[0054] Since switching losses need to be accumulated, continuous monitoring is required over a certain period of time. For the same H-bridge module, the cumulative switching loss is measured within a preset statistical time, and then the average cumulative switching loss of all H-bridge modules is calculated. In this embodiment, the preset statistical time is not limited.

[0055] In this embodiment, the average junction temperature of all H-bridge modules The calculation method is as follows: the effective junction temperature values ​​of all H-bridge modules Add them together and then divide by the total number of H-bridge modules to calculate the average junction temperature. .

[0056] Average cumulative switching loss of all H-bridge modules The calculation method is as follows: the cumulative switching loss of each H-bridge module within a preset statistical time period is calculated. Add them together and then divide by the total number of H-bridge modules to calculate the average cumulative switching loss. .

[0057] When calculating cumulative switching losses, if the statistical time is too long, it will affect the switching frequency of the high-frequency and low-frequency modules, making it difficult to achieve precise active adjustment. If the statistical time is too short, the average cumulative switching losses cannot be accurately estimated. Therefore, it is necessary to determine a suitable statistical time. In this embodiment, the preset statistical time is any time value within the range of 0.8 to 1.2 seconds, which can be 0.8 seconds, 1 second, 1.1 seconds, 1.2 seconds, or other time values. The specific time is not limited.

[0058] S3: For each H-bridge module, the rotation index of the H-bridge module is calculated based on the first absolute difference between the effective value of the junction temperature and the average junction temperature, and the second absolute difference between the cumulative switching loss and the average cumulative switching loss, combined with the preset temperature weighting coefficient and power loss weighting coefficient.

[0059] In this embodiment, the rotation index needs to be determined by combining the module junction temperature and cumulative switching losses. Therefore, appropriate weighting coefficients need to be determined for the module junction temperature and cumulative switching losses, namely, temperature weighting coefficient and power loss weighting coefficient, to reflect the emphasis of module junction temperature or switching losses in the rotation strategy. Specifically, the first absolute difference is the direct difference between the real-time junction temperature data and the average junction temperature of the same H-bridge module. The second absolute difference is the direct difference between the cumulative switching losses and the average cumulative switching losses of the same H-bridge module.

[0060] S4: Mark H-bridge modules with rotation indicators greater than the first preset threshold as high-frequency modules to be rotated, and mark H-bridge modules with rotation indicators less than the second preset threshold as low-frequency modules to be rotated.

[0061] S5: Based on the rotation index of each H-bridge module, send a pulse control signal of the corresponding frequency to adjust the switching frequency of the high-frequency module to be rotated to low-frequency mode and the switching frequency of the low-frequency module to be rotated to high-frequency mode.

[0062] In this embodiment, the operating frequency range of the high-frequency mode is 4kHz to 20kHz, preferably 5kHz; the operating frequency range of the low-frequency mode is 30Hz to 500Hz, preferably 50Hz.

[0063] The technical solution of this application embodiment collects junction temperature data and switching loss data of each H-bridge module in real time, and comprehensively evaluates the switching timing of high and low frequency modules by combining the two factors of "module junction temperature" and "switching loss" to determine the rotation index. This rotation index changes in real time, so the rotation of high and low frequency modules also switches in real time, effectively avoiding local overheating or excessive switching loss of a certain module. This dynamic rotation control method can balance the switching loss and thermal stress distribution of each H-bridge module in real time, ensuring the stable operation of the H-bridge converter under complex operating conditions, dynamically adjusting the module operating frequency to optimize thermal distribution, avoiding some modules from operating at high frequency for a long time, making the aging rate of each H-bridge module tend to be consistent, thereby significantly extending the service life of power devices; multi-objective collaborative optimization takes into account multiple key indicators such as power quality, harmonic optimization, power loss equalization, and thermal stress equalization, thereby improving the overall performance of the H-bridge converter.

[0064] In this embodiment, the method for switching a high-frequency module to be rotated to a low-frequency module is as follows: the switching frequency of the high-frequency module to be rotated is lowered. For example, if the original high-frequency module has a switching frequency of 5kHz, the switching frequency is lowered to 50Hz after rotation. The method for switching a low-frequency module to be rotated to a high-frequency module is as follows: the switching frequency of the low-frequency module to be rotated is raised. For example, if the original low-frequency module has a switching frequency of 50Hz, the switching frequency is raised to 5kHz after rotation.

[0065] In an optional embodiment, the rotation index is obtained as follows: for each H-bridge module, a first absolute difference is calculated based on the effective value of the junction temperature and the average junction temperature, and the product of the first absolute difference and the temperature weighting coefficient is used as the temperature equalization term.

[0066] For each H-bridge module, a second absolute difference is calculated based on the cumulative switching loss and the average cumulative switching loss. The product of the second absolute difference and the power loss weighting coefficient is used as the power loss balancing term. Among them, the sum of the temperature weighting coefficient and the power loss weighting coefficient is 1.

[0067] The arithmetic sum of the temperature equalization term and the power loss equalization term is used as the rotation index.

[0068] Specifically, the rotation index of each H-bridge module can be calculated using the following formula:

[0069] .

[0070] in, For the first Rotation metrics for each H-bridge module The first in the H-bridge converter RMS junction temperature of each H-bridge module. The average junction temperature of all H-bridge modules. For the first The cumulative switching loss of each H-bridge module within a preset statistical time period. The average cumulative switching loss over a preset statistical period for all H-bridge modules. The temperature weighting coefficient is dynamically rotated between high and low frequencies. This is the power loss weighting coefficient for dynamic switching between high and low frequencies.

[0071] The above formula can comprehensively consider the difference between the module junction temperature and switching loss and the average value, and quantify the degree of module replacement demand.

[0072] Among them, the temperature weighting coefficient and power loss weighting factor The temperature weighting coefficient is determined and adjusted based on the junction temperature and power loss characteristics of the H-bridge converter. The value range is 0.3~0.7, and the power loss weighting coefficient is... The value range is 0.3 to 0.7. This parameter range has been verified through extensive experiments and can achieve the optimal balance between temperature and loss equilibrium in different application scenarios. It avoids imbalance caused by over-focusing on one factor and ensures the effectiveness of the adjustment.

[0073] If the reliability of the H-bridge converter is easily affected by the module junction temperature, or if more attention is paid to the module junction temperature, then the temperature weighting coefficient should be adjusted. Increase the power loss weighting factor if necessary, otherwise decrease it if the reliability of the H-bridge converter is easily affected by switching losses or if more attention is paid to the switching losses of the H-bridge converter. Increase the value, otherwise decrease it.

[0074] In some embodiments, if more attention is paid to the impact of module junction temperature, the temperature weighting coefficient is adjusted. Setting it to 0.6 will adjust the power loss weighting factor. Set it to 0.4; if more attention is paid to the impact of module switching losses, the power loss weighting coefficient will be adjusted. Setting it to 0.6 will adjust the temperature weighting coefficient. Set to 0.4; if the module junction temperature and power loss are of equal concern, adjust the temperature weighting coefficient. It is 0.5. The value can be 0.5; in other embodiments, it can also be other values. Preferably, the temperature weighting coefficient is based on multiple experimental data or operating condition simulations. Setting it to 0.5 will adjust the power loss weighting factor. Set it to 0.5.

[0075] This is a temperature equalization term used to achieve thermal stress equalization and prevent local overheating. When the real-time temperature of a certain H-bridge module is higher than the average junction temperature of all H-bridge modules, this term is positive, increasing the rotation priority.

[0076] This is a power loss balancing term used to ensure that the switching losses of each H-bridge module are evenly distributed. Within a preset statistical time period, when the cumulative switching loss of a certain H-bridge module is higher than the average cumulative switching loss of all H-bridge modules, this term is positive, increasing the rotation priority.

[0077] By decomposing the rotation index into temperature equalization and power loss equalization terms, the deviation of each module in both temperature and power loss dimensions can be accurately quantified, providing a scientific basis for rotation decisions. The temperature equalization term mainly addresses the problem of thermal stress concentration, while the power loss equalization term mainly addresses the problem of uneven switching losses. The two work together to achieve multi-objective optimization.

[0078] The first preset threshold is a high-frequency rotation threshold, and the second preset threshold is a low-frequency rotation threshold; both are adjustable. The range of the first preset threshold is +0.4 to +0.6, and the range of the second preset threshold is -0.6 to -0.4. Reasonable threshold settings ensure the accuracy and timeliness of rotation decisions, avoid system instability caused by frequent switching, and prevent security risks caused by response lag.

[0079] In a preferred embodiment, the first preset threshold is +0.5, and the second preset threshold is -0.5. This is used when the rotation index of a certain H-bridge module... When the value exceeds the positive threshold +0.5, it indicates that the operating state exceeds the safety margin, and the control system will automatically adjust it to a low-frequency mode; conversely, when the switching index of a certain H-bridge module exceeds the threshold, it indicates that the operating state exceeds the safety margin. When the value falls below the negative threshold of -0.5, the system switches to high-frequency mode.

[0080] This dynamic adjustment mechanism, while ensuring the quality of the output waveform, realizes an intelligent rotation strategy of "high-temperature modules resting and low-temperature modules working". Compared with the traditional fixed allocation method, it can make the temperature of each H-bridge module nearly uniform and the switching losses of each H-bridge module balanced.

[0081] In some embodiments, the temperature weighting coefficient Power loss weighting coefficient The high-frequency switching threshold and the low-frequency switching threshold can be flexibly adjusted according to the specific application scenario. It is suitable for steady-state operation scenarios such as photovoltaic inverters, and can also meet the dynamic load requirements of motor drives, etc., and has significant practical engineering value.

[0082] In an optional embodiment, in step S1, determining the effective junction temperature value of each module based on real-time junction temperature data includes: calculating the average junction temperature data of each module within a preset statistical time period as the effective junction temperature value of the module; or, using the highest junction temperature data of each module within the preset statistical time period as the effective junction temperature value of the module. By providing two methods for calculating the effective junction temperature value, different application requirements can be met. The average junction temperature reflects the overall thermal state of the module and is suitable for steady-state conditions; the highest junction temperature reflects the extreme thermal state of the module and is suitable for dynamic conditions, enhancing the applicability and flexibility of the method.

[0083] Cumulative switching losses are obtained by integrating or summing instantaneous switching loss data over a preset statistical period. By calculating cumulative switching losses, the total losses of the module within the statistical period can be accurately reflected, providing a reliable data basis for rotation decisions.

[0084] In some H-bridge converters, the number of high-frequency modules and low-frequency modules are not the same. Therefore, the number of high-frequency modules to be replaced and the number of low-frequency modules to be replaced may also be inconsistent.

[0085] In specific high- and low-frequency switching applications, if the number of high-frequency modules to be switched is equal to the number of low-frequency modules to be switched, then the switching frequency of all high-frequency modules to be switched is directly adjusted to low-frequency mode, and the switching frequency of all low-frequency modules to be switched is adjusted to high-frequency mode.

[0086] If the number of high-frequency modules to be rotated is less than the number of low-frequency modules to be rotated, the low-frequency modules to be rotated are sorted in ascending order based on the value of the rotation index. Based on the number of high-frequency modules to be rotated, the top-ranked low-frequency modules are selected, and their switching frequencies are adjusted to high-frequency mode first. All high-frequency modules to be rotated are then adjusted to low-frequency mode.

[0087] If the number of high-frequency modules to be rotated is greater than the number of low-frequency modules to be rotated, the high-frequency modules to be rotated are sorted in descending order based on the value of the rotation index. Based on the number of low-frequency modules to be rotated, the top-ranked high-frequency modules to be rotated are selected, and their switching frequencies are adjusted to low-frequency mode first. All low-frequency modules to be rotated are then adjusted to high-frequency mode.

[0088] This rotation strategy effectively solves the problem of mismatch in the number of modules to be rotated. By prioritizing the modules that need to be rotated the most, it ensures that the modules that need to be rotated the most are processed first, which not only guarantees the fairness of the rotation but also improves the efficiency of the rotation and further optimizes the system performance.

[0089] Based on the above embodiments, it is also necessary to take into account the power output quality and realize power feedback regulation.

[0090] Optionally, operating parameters also include output current and output voltage, both of which can be monitored by a voltage and current detection circuit connected to the H-bridge module.

[0091] The method also includes the following steps: real-time acquisition of the output current and output voltage of the entire H-bridge converter; calculation of the actual output power of the H-bridge converter based on the output current and output voltage; calculation of the power difference between the actual output power and the preset output power; and adjustment of the duty cycle of the pulse control signal used to drive each H-bridge module based on the power difference, thereby enabling real-time monitoring of the power output quality of the H-bridge converter. By adding a power feedback adjustment function, the output power quality can be guaranteed while realizing module switching, achieving multi-objective collaborative optimization and further improving the overall performance of the system.

[0092] According to an embodiment of this application, an H-bridge converter control system is also provided, including an H-bridge converter, a real-time monitoring module, and a controller.

[0093] An H-bridge converter includes multiple H-bridge modules with the same configuration, but they may operate in different modes.

[0094] The real-time monitoring module is electrically connected to each H-bridge module and is used to collect the operating parameters of each H-bridge module in real time and transmit them to the controller. The operating parameters include at least the module junction temperature and switching losses.

[0095] The controller, electrically connected to the real-time monitoring module, is used to receive operating parameters and execute the H-bridge converter control method based on dynamically rotating high and low frequency modules as described in the above embodiment, generating and outputting pulse control signals for controlling the switching frequency of each H-bridge module.

[0096] In this embodiment, the output of the controller is connected to each switch of the H-bridge converter. After the controller makes a rotation decision based on the operating parameters collected by the real-time monitoring module, it generates a pulse control signal and sends it to the switches of each H-bridge module, thereby controlling the high and low frequency modules of the entire H-bridge converter to switch in a timely manner. While ensuring the quality of power output, it can take into account problems such as switching loss balance and thermal stress balance, and significantly improve the loss balance and temperature consistency of the H-bridge converter.

[0097] For ease of description, the above system is described by dividing it into various modules based on their functions. Of course, in implementing this invention, the functions of each module can be implemented in one or more software and / or hardware components.

[0098] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0099] The above embodiments merely illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A control method for an H-bridge converter based on dynamically rotating high- and low-frequency modules, characterized in that, include: For each H-bridge module, real-time junction temperature data is collected based on a preset junction temperature sampling frequency, the effective value of the junction temperature is determined based on the real-time junction temperature data, instantaneous switching loss data is collected based on a preset power loss sampling frequency, and the cumulative switching loss within a preset statistical time period is calculated. Obtain the total number of H-bridge modules in the entire H-bridge converter, calculate the average junction temperature of all H-bridge modules based on the effective junction temperature value, and calculate the average cumulative switching loss of all H-bridge modules based on the cumulative switching loss. For each H-bridge module, a first absolute difference is calculated based on the effective junction temperature and the average junction temperature. The product of the first absolute difference and the temperature weighting coefficient is used as a temperature balancing term. A second absolute difference is calculated based on the cumulative switching loss and the average cumulative switching loss. The product of the second absolute difference and the power loss weighting coefficient is used as a power loss balancing term. The arithmetic sum of the temperature balancing term and the power loss balancing term is used as a rotation index, wherein the sum of the temperature weighting coefficient and the power loss weighting coefficient is 1. H-bridge modules with a rotation index greater than a first preset threshold are marked as high-frequency modules to be rotated, and H-bridge modules with a rotation index less than a second preset threshold are marked as low-frequency modules to be rotated. According to the rotation index of each H-bridge module, a pulse control signal of the corresponding frequency is sent to adjust the switching frequency of the high-frequency module to be rotated to low-frequency mode and the switching frequency of the low-frequency module to be rotated to high-frequency mode.

2. The H-bridge converter control method based on dynamically rotating high and low frequency modules according to claim 1, characterized in that, The temperature weighting coefficient ranges from 0.3 to 0.7, and the power loss weighting coefficient ranges from 0.3 to 0.

7.

3. The H-bridge converter control method based on dynamically rotating high and low frequency modules according to claim 2, characterized in that, The first preset threshold value ranges from +0.4 to +0.6, and the second preset threshold value ranges from -0.6 to -0.

4.

4. The H-bridge converter control method based on dynamically rotating high and low frequency modules according to claim 1, characterized in that, The step of determining the effective junction temperature value based on the real-time junction temperature data includes: for each module, calculating the average junction temperature data within a preset statistical time period as the effective junction temperature value of the module; or, using the highest junction temperature data within the preset statistical time period as the effective junction temperature value of the module.

5. The H-bridge converter control method based on dynamically rotating high and low frequency modules according to claim 1, characterized in that, The cumulative switching loss is obtained by integrating or summing the instantaneous switching loss data over a preset statistical time period.

6. The H-bridge converter control method based on dynamically rotating high and low frequency modules according to claim 1, characterized in that, During the high-frequency and low-frequency module rotation, if the number of high-frequency modules to be rotated is equal to the number of low-frequency modules to be rotated, then the switching frequencies of all high-frequency modules to be rotated are directly adjusted to low-frequency mode, and the switching frequencies of all low-frequency modules to be rotated are adjusted to high-frequency mode. If the number of high-frequency modules to be rotated is less than the number of low-frequency modules to be rotated, the low-frequency modules to be rotated are sorted in ascending order based on the value of the rotation index. Based on the number of high-frequency modules to be rotated, the top-ranked low-frequency modules are selected, and their switching frequencies are preferentially adjusted to high-frequency mode. All high-frequency modules to be rotated are then adjusted to low-frequency mode. If the number of high-frequency modules to be rotated is greater than the number of low-frequency modules to be rotated, the high-frequency modules to be rotated are sorted in descending order based on the value of the rotation index. Based on the number of low-frequency modules to be rotated, the top-ranked high-frequency modules are selected, and their switching frequencies are preferentially adjusted to low-frequency mode. All low-frequency modules to be rotated are then adjusted to high-frequency mode.

7. The H-bridge converter control method based on dynamically rotating high and low frequency modules according to claim 1, characterized in that, The preset power loss sampling frequency is not less than 10kHz.

8. The H-bridge converter control method based on dynamically rotating high and low frequency modules according to claim 1, characterized in that, The method further includes the following steps: real-time acquisition of the output current and output voltage of the entire H-bridge converter, calculation of the actual output power of the H-bridge converter based on the output current and the output voltage, obtaining the power difference value between the actual output power and the preset output power, and adjusting the duty cycle of the pulse control signal based on the power difference value.

9. An H-bridge converter control system, characterized in that, include: An H-bridge converter, which includes multiple H-bridge modules; A real-time monitoring module, connected to each of the H-bridge modules, is used to collect the operating parameters of each H-bridge module in real time. The operating parameters include at least real-time junction temperature data and switching loss data. A controller, electrically connected to the real-time monitoring module, is used to receive the operating parameters and execute the H-bridge converter control method based on dynamically rotating high and low frequency modules as described in any one of claims 1 to 8, generating and outputting pulse control signals for controlling the operation of each H-bridge module.

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