Switching frequency switching method, device and equipment of bidirectional dc converter and medium

Abstract

The application discloses a switching frequency switching method, device, equipment and medium of a bidirectional direct current converter. The method comprises: collecting operation parameters of the bidirectional direct current converter; determining a target switching frequency from a candidate switching frequency set according to the operation parameters; performing frequency switching management on the switching of the target switching frequency, and updating the output of pulse width modulation of the bidirectional direct current converter according to the result of the frequency switching management; the frequency switching management comprises at least one of hysteresis interval management, minimum holding time management and soft switching management. By performing frequency switching management on the switching of the target switching frequency, at least one management mechanism of hysteresis interval management, minimum holding time management and soft switching management is introduced in the frequency switching process, the problem that the frequent jump of the frequency near the boundary caused by the traditional frequency switching method seriously affects the stability of the switching frequency switching is solved, and the beneficial effect of guaranteeing the stability of the switching frequency switching is achieved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a method, apparatus, equipment and medium for switching frequency of a bidirectional DC-DC converter. Background Technology

[0002] In energy storage conversion systems, bidirectional DC-DC converters are typically used to enable bidirectional energy flow between the battery and the DC bus. Their core functions include charging, discharging, and power regulation.

[0003] In existing solutions, bidirectional DC / DC converters generally adopt a fixed switching frequency control method, that is, maintaining the same switching frequency under all operating conditions. This method is simple to implement, but it has obvious limitations in wide voltage range and bidirectional power flow scenarios: when the switching frequency is set higher, the inductor current ripple usually decreases, and the size of magnetic components and control accuracy may benefit, but the switching losses, drive losses, electromagnetic compatibility (EMC) risks, and device temperature rise of power devices will increase significantly, especially under high bus voltage, high power, or high temperature conditions; when the switching frequency is set lower, the switching losses of power devices decrease, which is beneficial to efficiency and thermal design, but the inductor current ripple increases, which may lead to problems such as magnetic component saturation risk, increased RMS current of bus capacitor, increased sampling error, control loop disturbance, and protection malfunction.

[0004] To address the aforementioned issues, while a variable frequency control approach based on switching frequency changes according to operating conditions has been proposed, this approach has revealed new problems in practical applications: although it is recognized that the switching frequency should be adjusted according to operating conditions, there is a lack of systematic management of the frequency switching process itself. During the frequency switching process, the frequency frequently jumps near the operating condition boundary, which can easily cause control oscillation problems and restrict the reliable application of variable frequency control technology in bidirectional DC / DC converters. Summary of the Invention

[0005] This application provides a switching frequency switching method, apparatus, device, and medium for a bidirectional DC-DC converter. By performing frequency switching management on the target switching frequency, at least one of the following management mechanisms is introduced during the frequency switching process: hysteresis interval management, minimum hold time management, and soft switching management. This solves the problem that traditional frequency switching methods cause frequent frequency jumps near the operating condition boundary, which can easily lead to control oscillations.

[0006] In a first aspect, embodiments of this application provide a switching frequency switching method for a bidirectional DC-DC converter, including: Collect operating parameters of the bidirectional DC-DC converter; The target switching frequency is determined from the candidate switching frequency set based on the operating parameters. Frequency switching management is performed on the switching of the target switching frequency, and the pulse width modulation output of the bidirectional DC-DC converter is updated according to the result of the frequency switching management; the frequency switching management includes at least one of hysteresis interval management, minimum hold time management and soft switching management.

[0007] Secondly, embodiments of this application provide a switching frequency switching device for a bidirectional DC-DC converter, comprising: The parameter acquisition module is used to acquire the operating parameters of the bidirectional DC-DC converter. A frequency determination module is used to determine a target switching frequency from a set of candidate switching frequencies based on the operating parameters; The frequency switching module is used to perform frequency switching management on the switching of the target switching frequency, and update the pulse width modulation output of the bidirectional DC-DC converter according to the result of the frequency switching management; the frequency switching management includes at least one of hysteresis interval management, minimum hold time management and soft switching management.

[0008] Thirdly, embodiments of this application provide an electronic device, the electronic device comprising: At least one processor; and a memory communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, which is then executed by the at least one processor to enable the at least one processor to perform the switching frequency switching method of the bidirectional DC-DC converter according to any embodiment of this application.

[0009] Fourthly, embodiments of this application provide a computer-readable storage medium storing computer instructions, which are used to cause a processor to execute and implement the switching frequency switching method of the bidirectional DC-DC converter described in any embodiment of this application.

[0010] The technical solution of this application embodiment collects the operating parameters of a bidirectional DC-DC converter; determines the target switching frequency from a set of candidate switching frequencies based on the operating parameters; performs frequency switching management on the switching of the target switching frequency; and updates the pulse width modulation output of the bidirectional DC-DC converter based on the result of the frequency switching management. The frequency switching management includes at least one of hysteresis interval management, minimum hold time management, and soft switching management. By performing frequency switching management on the switching of the target switching frequency and introducing at least one of the management mechanisms of hysteresis interval management, minimum hold time management, and soft switching management during the frequency switching process, the problem of frequent frequency jumps near the operating condition boundary caused by traditional frequency switching methods, which easily leads to control oscillations, is solved, thus having the beneficial effect of ensuring the stability of switching frequency switching.

[0011] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent from the following description. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 A flowchart of a switching frequency switching method for a bidirectional DC-DC converter provided in Embodiment 1 of this application; Figure 2 A flowchart of a switching frequency switching method for a bidirectional DC-DC converter provided in Embodiment 2 of this application; Figure 3 This is a schematic diagram of the switching frequency switching device for a bidirectional DC-DC converter provided in Embodiment 3 of this application; Figure 4 A schematic diagram of the structure of an electronic device for implementing the switching frequency switching method of the bidirectional DC-DC converter in the embodiments of this application. Detailed Implementation

[0014] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0015] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0016] It is understood that before using the technical methods disclosed in the various embodiments of this disclosure, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in this disclosure in an appropriate manner in accordance with relevant laws and regulations, and user authorization should be obtained.

[0017] Example 1 Figure 1 This is a flowchart illustrating a switching frequency switching method for a bidirectional DC / DC converter according to Embodiment 1 of this application. This embodiment is applicable to adaptive switching frequency control of a bidirectional DC / DC converter in an energy storage conversion system. The method can be executed by a switching frequency switching device of the bidirectional DC / DC converter, which can be implemented in hardware and / or software and can be configured in an electronic device. Figure 1 As shown, the method includes: S110: Collect the operating parameters of the bidirectional DC-DC converter.

[0018] A bidirectional DC-DC converter is a DC / DC power converter capable of bidirectional energy flow. Typical applications include, but are not limited to, energy management for charging and discharging between batteries and the DC bus in energy storage systems. Operating parameters refer to information reflecting the current operating status and environment of the bidirectional DC-DC converter.

[0019] In one optional implementation, the operating parameters include voltage, current, output power, power direction, power device temperature, magnetic component temperature, and operating mode. Voltage may include battery-side voltage and DC bus voltage; current may include battery-side current, inductor current, etc.; power direction indicates whether the current energy flow direction is charging or discharging; output power characterizes the power level currently being processed by the converter; power device temperature refers to the junction or case temperature of power switching devices (such as SiC MOSFETs); magnetic component temperature refers to the winding temperature or core temperature of magnetic components such as inductors and transformers; operating mode refers to the current operating mode of the converter, such as constant current charging mode, constant voltage charging mode, constant power discharging mode, etc. The operating parameters can be acquired through hardware such as voltage sensors, current sensors, temperature sensors, and power detection circuits. The sampling frequency can be configured according to the system control cycle, for example, from 10kHz to 100kHz, with no specific value limited.

[0020] For example, the battery-side voltage and DC bus voltage are collected by a voltage sensor, the battery-side current and inductor current are collected by a current sensor, the temperature of the power device and the temperature of the magnetic component are collected by a temperature sensor, and the output power and power direction are collected by a power detection circuit; the operating mode is determined by the data collected by the voltage sensor and the current sensor.

[0021] S120. Determine the target switching frequency from the candidate switching frequency set based on the operating parameters.

[0022] The candidate switching frequency set refers to a predefined set of selectable switching frequency values ​​defined by the system. This set may include multiple discrete frequency values, such as 16kHz, 24kHz, 32kHz, and 40kHz. In practical applications, the candidate switching frequencies can also be set to a continuously adjustable frequency range, or expanded and calibrated according to product requirements and device characteristics; this application does not impose any limitations on this. The target switching frequency refers to the most suitable switching frequency value selected from the candidate switching frequency set after multi-dimensional constraint evaluation and comprehensive decision-making.

[0023] In one optional implementation, the process of determining the target switching frequency from the candidate switching frequency set based on operating parameters includes: first, identifying the current operating condition of the bidirectional DC-DC converter based on the operating parameters; then, calculating evaluation indicators for each candidate switching frequency in the candidate switching frequency set; and finally, determining the target switching frequency suitable for the current operating condition from the candidate switching frequency set based on the indicator calculation results under the current operating condition.

[0024] In this embodiment, the frequency decision algorithm for determining the target switching frequency from the candidate switching frequency set can employ methods such as table lookup, piecewise functions, linear interpolation, model prediction, multi-objective optimization, weighted scoring, or priority rules. The constraint model can also be flexibly configured according to the product stage: simulation models and empirical tables are used in the early design stage; double-pulse, thermal, ripple, and EMC test data are introduced for correction in the prototype stage; and software parameters or online calibration are used to adapt to different batches of devices and magnetic components in the mass production stage.

[0025] S130. Perform frequency switching management on the target switching frequency and update the pulse width modulation output of the bidirectional DC-DC converter according to the result of the frequency switching management; the frequency switching management includes at least one of hysteresis interval management, minimum hold time management and soft switching management.

[0026] Frequency switching management refers to a series of constraints and control strategies applied to the process of switching the switching frequency from the current value to the target value. Its purpose is to prevent the switching frequency from repeatedly jumping near the operating boundary, ensuring the smoothness of the switching process and the control stability of the system. Pulse Width Modulation (PWM) output update refers to sending the target switching frequency, after frequency switching management, to the PWM generation module to adjust the frequency of the drive signal for the power switching devices.

[0027] Hysteresis interval management refers to setting different trigger thresholds for forward frequency switching (such as switching from low frequency to high frequency) and reverse switching (such as switching from high frequency to low frequency) during frequency switching. A difference (i.e., hysteresis interval) exists between the two thresholds, making frequency switching directionally dependent and thus creating a dead zone (i.e., a non-operational interval) near the switching boundary. Specifically, hysteresis interval management means that when at least one of the operating parameters reaches a preset switching threshold, there is a hysteresis interval between the first switching threshold for switching from the current switching frequency to the target switching frequency and the second switching threshold for switching back from the target switching frequency to the current switching frequency.

[0028] Minimum hold time management refers to limiting the minimum time interval between frequency switching operations during frequency switching. Essentially, it requires the current switching frequency to stabilize for a preset time before the next frequency switch is allowed. In essence, it imposes constraints on frequency switching behavior in the time dimension, prohibiting frequent frequency changes within a short period.

[0029] Soft handover management refers to the process where, when the difference between the target switching frequency and the current switching frequency exceeds a preset rate of change limit, the switching frequency is not directly switched to the target frequency, but rather gradually adjusted to the target frequency. Essentially, it limits the magnitude of a single frequency switch, breaking down a large, one-time jump into multiple smaller steps to gradually approach the target value.

[0030] In this embodiment, by implementing hysteresis interval management for the switching of the target switching frequency, it is possible to prevent repeated switching of the switching frequency caused by minor fluctuations in operating parameters near the switching threshold, thereby avoiding disturbances to the control loop and system stability caused by frequency jitter. Physically, the hysteresis interval is similar to the hysteresis characteristic of a Schmitt trigger. By setting different rising switching thresholds and falling back thresholds, a dead zone is formed between the thresholds, ensuring that fluctuations in parameters within this dead zone will not trigger frequency switching.

[0031] By implementing minimum hold-up time management for target switching frequencies, it ensures that the system operates stably for a sufficient period at each switching frequency. This allows the control loop, sampling system, and protection circuits ample time to adapt to the new switching frequency, preventing the system from remaining in a transient state and failing to reach steady state due to excessively frequent frequency switching. Furthermore, it prevents unnecessary frequency switching triggered by instantaneous fluctuations in operating parameters or noise interference. The preset time can be set according to the system control cycle and dynamic response characteristics, such as 100ms, or configured based on the control cycle; the specific value is not limited.

[0032] When the switching frequency needs to change significantly (e.g., jumping directly from 16kHz to 40kHz), if an instantaneous switching method is used, the abrupt change in the PWM cycle may lead to problems such as a mismatch between the sampling window and the control cycle, incorrect calculation of control loop adjustments, and false triggering of protection judgments. By implementing soft switching management for the target switching frequency, the disturbance of frequency changes to the control loop and sampling synchronization can be reduced, ensuring the smoothness of the switching process. In an optional embodiment, the frequency switching management includes hysteresis interval management, minimum hold time management, and soft switching management.

[0033] This embodiment combines hysteresis interval management, minimum hold time management, and soft switching management to construct a complete frequency switching management mechanism from three dimensions: threshold constraints for hysteresis interval management, time constraints for minimum hold time management, and rate-of-change constraints for soft switching management. For bidirectional DC-DC converters, this coordinated approach enables the system to exhibit "gradual transition and steady-state hold" characteristics near the operating boundary, avoiding the risk of runaway caused by frequent switching frequency jumps between high and low frequencies. Furthermore, the combination of these three mechanisms allows the system to adaptively adjust the sensitivity of the switching management strategy according to different operating conditions. For example, when a rapid response to load changes is required, the hysteresis width can be narrowed and the hold time shortened, while the soft switching step can be increased to ensure the response speed of the switching frequency. When under light load or in a steady-state standby state, the hysteresis can be widened and the hold time extended to prioritize efficiency.

[0034] In another optional embodiment, to ensure the safety of the system and equipment in the event of abnormal switching frequency changes, frequency switching management may also include abnormal rollback management. Abnormal rollback management refers to forcibly switching the switching frequency to a preset safe frequency, or controlling the converter to enter a derating operation mode or protection mode when an abnormal state is detected, to ensure the safety of the system and equipment. Essentially, in abnormal states, frequency decision-making shifts from pursuing overall optimality to ensuring system safety.

[0035] Specifically, when the system detects abnormal conditions such as over-temperature, over-current, abnormal sampling, excessive voltage fluctuations, or increased EMC risk levels, the optimal frequency decision under the current operating conditions may no longer be applicable or may even exacerbate the abnormality. By implementing abnormal rollback management for the target switching frequency, frequency switching management will prioritize system safety, forcibly rolling back the switching frequency to a preset safe frequency (such as a lower, fully verified reliable frequency), or coordinating with derating operations (such as limiting output power or current) and protection actions (such as over-temperature shutdown and over-current shutdown) to ensure equipment safety.

[0036] As an optional embodiment, hysteresis interval management includes voltage hysteresis interval management and / or current hysteresis interval management. The voltage hysteresis interval management is as follows: When the voltage rises to a level not less than the sum of the first voltage threshold and the preset hysteresis voltage, a frequency upsampling switch is performed to switch from the current switching frequency to the target switching frequency. When the voltage drops to a value no greater than the difference between the first voltage threshold and the preset hysteresis voltage, a frequency reduction switching is performed to switch from the current switching frequency to the target switching frequency. When the voltage is within a range that is greater than the difference between the first voltage threshold and the preset hysteresis voltage, and less than the sum of the first voltage threshold and the preset hysteresis voltage, the current switching frequency is maintained unchanged.

[0037] The first voltage threshold refers to the preset nominal voltage value for triggering frequency switching; the preset hysteresis voltage refers to the hysteresis voltage value (e.g., 5V) set to avoid boundary jitter. For example, if the first voltage threshold is 340V and the preset hysteresis voltage is 5V, then frequency upscaling is triggered when the voltage rises from low to high to 345V (340V+5V), and frequency downscaling is triggered when the voltage falls from high to low to 335V (340V-5V), maintaining the current frequency between 335V and 345V. It should be noted that the above voltage threshold and hysteresis voltage values ​​are only examples; in actual projects, calibration should be performed according to the battery pack voltage range, bus voltage specifications, rated power, and component selection.

[0038] The current hysteresis interval management is as follows: When the current rises to a level not less than the sum of the first current threshold and the preset hysteresis current, a frequency upswitching switch is performed, switching from the current switching frequency to the target switching frequency corresponding to the first current threshold. When the current drops to no more than the difference between the first current threshold and the preset hysteresis current, a frequency reduction switching is performed to switch from the current switching frequency to the target switching frequency. When the current is within a range that is greater than the difference between the first current threshold and the preset hysteresis current, and less than the sum of the first current threshold and the preset hysteresis current, the current switching frequency is maintained unchanged.

[0039] The first current threshold refers to the nominal current value for the preset trigger frequency switching; the preset hysteresis current refers to the hysteresis current value set to avoid boundary jitter. Its working principle is similar to voltage hysteresis range management. By applying hysteresis characteristics to the current signal, it avoids repeated switching of the switching frequency caused by small fluctuations in the current near the threshold.

[0040] The technical solution of this application embodiment collects the operating parameters of the bidirectional DC-DC converter; determines the target switching frequency from the candidate switching frequency set based on the operating parameters; performs frequency switching management on the switching of the target switching frequency; and updates the pulse width modulation output of the bidirectional DC-DC converter based on the result of the frequency switching management. The frequency switching management includes at least one of hysteresis interval management, minimum hold time management, and soft switching management. By introducing at least one of the management mechanisms of hysteresis interval management, minimum hold time management, and soft switching management during the frequency switching process, this application effectively avoids frequent frequency jumps near the operating condition boundary and even control oscillations, thus ensuring the stability of the switching frequency switching. In addition, abnormal rollback management is introduced into the frequency switching management to further ensure the safety of the switching frequency switching.

[0041] Example 2 Figure 2 This is a flowchart illustrating a switching frequency method for a bidirectional DC-DC converter according to Embodiment 2 of this application. Based on Embodiment 1, this embodiment further refines the process of determining the target switching frequency, specifically detailing the meaning and function of multi-dimensional constraint indicators and the process of frequency decision-making based on these constraints. For details not described in this embodiment, please refer to the above embodiments. Figure 2 As shown, the method includes: S210: Collect the operating parameters of the bidirectional DC-DC converter.

[0042] S220. Identify the current operating condition of the bidirectional DC-DC converter based on the operating parameters.

[0043] The current operating condition refers to the type of operating state of the bidirectional DC-DC converter identified based on the collected operating parameters.

[0044] In this embodiment, by analyzing the operating parameters, the current operating condition of the converter can be determined. The current operating condition may be one of the following: low battery voltage charging, high battery voltage discharging, light load, full load, high bus voltage, low bus voltage, high temperature, thermally limited, ripple-sensitive, EMC-sensitive, or abnormal protection condition. Operating condition identification can be achieved using rule-based judgment or state machine methods.

[0045] For example, when the battery voltage is low and the power direction is the charging direction, it is identified as a low battery voltage charging condition; when the output power is close to the rated power, it is identified as a full load condition; when the temperature of the power device exceeds the preset temperature threshold, it is identified as a high temperature or thermally limited condition; when the bus voltage is high, it is identified as a high bus voltage condition; when the current ripple is close to the preset limit value, it is identified as a ripple sensitive condition; when overcurrent, overvoltage, overtemperature or sampling abnormality is detected, it is identified as an abnormal protection condition.

[0046] The operating condition identification in this step provides a contextual basis for subsequent constraint calculations and frequency decisions, enabling different constraint priorities and decision strategies to be adopted under different operating conditions.

[0047] S230. For each candidate switching frequency in the candidate switching frequency set, calculate the result of the candidate switching frequency under the multi-dimensional constraint index.

[0048] Among them, the multi-dimensional constraint index refers to the index system that evaluates candidate switching frequencies from multiple technical dimensions. Each constraint index is for specific physical or engineering constraints and calculates the feasibility or superiority of the candidate switching frequency under that dimension.

[0049] In one optional embodiment, the multi-dimensional constraint indicators include at least one of the following: power device loss constraint indicators, magnetic component ripple and saturation constraint indicators, magnetic core and winding loss and temperature rise constraint indicators, bus capacitor ripple current constraint indicators, electromagnetic compatibility risk constraint indicators, control and sampling margin constraints, and protection margin constraints.

[0050] The meaning of power device loss constraint is to calculate the conduction loss, switching loss, and drive loss of the power switching device at each candidate switching frequency, and to evaluate the junction temperature margin of the power device. Among these, conduction loss is related to the RMS current and the on-resistance of the device, and is less affected by the switching frequency; switching loss is directly proportional to the switching frequency, with higher frequencies resulting in greater switching losses; drive loss is also directly proportional to the switching frequency. The purpose of this constraint is that, under high power, high bus voltage, or high temperature conditions, if switching loss becomes the dominant factor in system losses, this constraint will guide the frequency decision to favor the selection of a lower switching frequency to reduce the switching losses and temperature rise of the power device, ensuring that the device junction temperature remains within the safe operating range.

[0051] The meaning of the magnetic component ripple and saturation constraint index refers to calculating the peak-to-peak value of the inductor current ripple, the peak inductor current, and the saturation margin of the magnetic component for each candidate switching frequency. Specifically, the inductor current ripple is inversely proportional to the switching frequency; the lower the frequency, the larger the ripple. The peak current equals the average current plus half of the ripple current. The saturation margin is the difference between the core saturation current and the peak current. The purpose of this constraint index is to guide the frequency decision to select a higher switching frequency under ripple-sensitive conditions such as low voltage, high current, or light load, where excessive inductor current ripple may lead to core saturation, increased sampling errors, or protection malfunctions. This constraint ensures sufficient saturation margin while reducing ripple.

[0052] The meaning of the core and winding loss and temperature rise constraint index is to calculate the core loss (mainly including hysteresis loss and eddy current loss, which are related to frequency and flux density swing) and winding copper loss (related to the effective value of current and winding resistance) for each candidate switching frequency, and to evaluate the temperature rise of the magnetic components. The purpose of this constraint index is to limit the upper limit of the switching frequency when the increase in switching frequency leads to a significant increase in core loss and the temperature rise of the magnetic components exceeds the allowable range, or to work in conjunction with current limiting strategies to control the total loss and temperature rise of the magnetic components, ensuring that the magnetic components operate within a safe temperature range.

[0053] The bus capacitor ripple current constraint refers to evaluating the effective value of the ripple current flowing through the DC bus capacitor and the resulting thermal stress for each candidate switching frequency. The magnitude of the bus capacitor ripple current is related to the inductor current ripple and the converter's operating mode. The purpose of this constraint is to guide frequency decisions towards increasing the switching frequency or switching frequency range when the bus capacitor ripple current approaches the capacitor's rated ripple current limit, thereby reducing the ripple current amplitude and protecting the bus capacitor from overheating and lifespan degradation.

[0054] Electromagnetic compatibility (EMC) risk constraints refer to the assessment of the distribution of a candidate switching frequency and its harmonic components within the EMC-sensitive frequency band, as well as the suppression capability of existing filters for conducted and radiated emissions at that frequency, for each candidate switching frequency. The purpose of these constraints is to mark a candidate frequency as high-risk or eliminate it when its harmonics fall into an EMC-sensitive frequency band (such as communication bands or bands with specific electromagnetic environment requirements), guiding frequency decisions to avoid EMC-sensitive bands, reducing electromagnetic interference risks and the difficulty of filter design.

[0055] The meaning of the control and sampling margin constraint index is to evaluate whether there is sufficient margin for sampling synchronization, control loop bandwidth, PWM update cycle, and protection response time at each candidate switching frequency. The purpose of this constraint index is to avoid the matching relationship between the sampling window and the control cycle being disrupted due to sudden changes in switching frequency, the control loop not being able to respond in time, or the protection judgment being misjudged or the control being unstable, thereby ensuring the stability and reliability of the control system during frequency switching.

[0056] The meaning of protection margin constraint is to evaluate the margin of protection thresholds such as overcurrent protection, overvoltage protection, and overtemperature protection under the current operating parameters for each candidate switching frequency, and to determine whether the candidate switching frequency will lead to a narrowing of the protection boundary. The purpose of this constraint index is to guide the system back to the preset safe frequency or trigger derating operation and protection actions when abnormal states such as overtemperature, overcurrent, abnormal bus voltage, or abnormal current sampling are detected, so as to ensure equipment safety.

[0057] S240. Under the current operating conditions, determine the target switching frequency from the candidate switching frequency set based on the calculation results of the multi-dimensional constraint indicators.

[0058] In this embodiment, the emphasis of frequency decision-making differs under different operating conditions. For example, under high power and high device temperature conditions, if switching losses are the main limiting factor of the system, and inductor ripple, magnetic saturation, and EMC constraints all meet the requirements, then the frequency decision-making tends to select a lower switching frequency to reduce switching losses. However, under low power, low voltage, or high ripple sensitive conditions, if the inductor current ripple or the root mean square current of the bus capacitance is close to the limit value, then the frequency decision-making tends to select a higher switching frequency to reduce ripple.

[0059] In one optional implementation, determining the target switching frequency from the candidate switching frequency set based on the calculation results of the multi-dimensional constraint index includes: A. Remove candidate switching frequencies from the candidate switching frequency set that do not meet the hard safety constraints.

[0060] Among them, hard safety constraints refer to the bottom-line constraints that must be met and involve the safety of equipment and personnel. Hard safety constraints include at least one of the following: the saturation margin of magnetic components is lower than a preset threshold, the junction temperature of power devices exceeds a preset limit, and the ripple current of bus capacitors exceeds a preset limit.

[0061] Specifically, if the saturation margin of a magnetic component is lower than a preset threshold, it means that at a certain candidate switching frequency, the peak inductor current is close to or exceeds the core saturation current. If the device operates at this frequency, it will cause core saturation, a sharp drop in inductance, and current runaway, which may damage the power device. Therefore, this candidate frequency must be eliminated. If the junction temperature of a power device exceeds a preset limit, it means that at a certain candidate switching frequency, the switching and conduction losses of the power device cause the junction temperature to exceed the maximum allowable junction temperature specified in the device datasheet. If the device continues to operate at this frequency, it will cause thermal failure. Therefore, this candidate frequency must be eliminated. If the ripple current of a bus capacitor exceeds a preset limit, it means that at a certain candidate switching frequency, the ripple current flowing through the capacitor exceeds its rated value, which will cause the capacitor to overheat, have its lifespan drastically shortened, or even fail. Therefore, this candidate frequency must be eliminated.

[0062] By eliminating candidate switching frequencies that do not meet the hard safety constraints, it can be ensured that the final selected target switching frequency will not endanger the safety of equipment and personnel under any circumstances.

[0063] B. The remaining candidate switching frequencies are comprehensively scored using multi-dimensional scoring indicators, and the target switching frequency is determined based on the scoring results.

[0064] Among them, multi-dimensional scoring indicators refer to performance evaluation dimensions used to measure the overall merits of candidate switching frequencies, under the premise that safety hard constraints are met. Multi-dimensional scoring indicators include at least one of the following: efficiency, temperature rise, ripple, electromagnetic compatibility, and power density.

[0065] The efficiency rating metric evaluates the overall power conversion efficiency of a bidirectional DC-DC converter at candidate switching frequencies, specifically the ratio of output power to input power. Higher efficiency indicates lower energy loss. Its role in frequency decision-making is to prioritize more efficient candidate switching frequencies while meeting safety constraints, thereby reducing system energy loss, cooling requirements, and operating costs. The efficiency rating can comprehensively consider weighted efficiency at different voltage and power points, for example, assigning higher weight to frequently occurring high-frequency operating conditions.

[0066] (2) The temperature rise rating index is used to evaluate the temperature rise of power devices and magnetic components at candidate switching frequencies. The smaller the temperature rise, the lower the thermal stress and the more sufficient the thermal design margin. The role of this index in frequency decision-making is to prioritize the selection of candidate switching frequencies with lower temperature rises in high-temperature environments or under conditions where heat dissipation is limited, so as to ensure that devices and magnetic components operate reliably within the allowable temperature range and extend the service life of the equipment.

[0067] (3) The meaning of the ripple rating index is to evaluate the magnitude of the inductor current ripple and the output voltage ripple at the candidate switching frequency. The smaller the ripple, the higher the power quality and the smaller the impact on sampling accuracy and control loop. The role of this index in frequency decision-making is to prioritize the candidate switching frequency with smaller ripple under ripple-sensitive operating conditions (such as light load and high-precision sampling requirements) in order to improve control accuracy and system stability.

[0068] (4) The meaning of the electromagnetic compatibility (EMC) rating index is to evaluate the margin between the electromagnetic emission level of the converter at the candidate switching frequency and the relevant standard limits. The larger the EMC margin, the greater the chance of passing the EMC certification. The role of this index in frequency decision-making is to prioritize the candidate switching frequency with a larger EMC margin in EMC-sensitive operating conditions or scenarios that need to meet stringent EMC standards, thereby reducing the risk of electromagnetic interference.

[0069] (5) The power density rating index is used to evaluate the power density level that the converter can achieve at the candidate switching frequency, that is, the power that can be processed per unit volume or per unit weight. The higher the switching frequency, the smaller the magnetic components and filter components can usually be used, thereby improving the power density. The role of this index in frequency decision-making is to prioritize candidate switching frequencies that are conducive to improving power density in application scenarios with strict requirements on size and weight (such as vehicle-mounted and portable devices), provided that other constraints are met.

[0070] In practical applications, the comprehensive evaluation can be achieved using a weighted summation method, assigning different weights to evaluation indicators for different operating conditions. For example, under full-load, high-temperature conditions, the efficiency and temperature rise evaluation indicators can be given higher weights; under light-load, ripple-sensitive conditions, the ripple evaluation indicator can be given a higher weight; and in scenarios requiring compliance with stringent electromagnetic compatibility standards, the electromagnetic compatibility evaluation indicator can be given a higher weight. The candidate switching frequency with the highest comprehensive score is determined as the target switching frequency.

[0071] Using the frequency switching method of this application, the switching frequency can be increased in the medium-voltage range to reduce inductor ripple and peak current pressure, freeing up optimization space for reactor inductance and size. In the low-frequency range, the ripple and saturation constraints for current-limited or high-voltage drop-off conditions can be met through current limiting and thermal design. Therefore, the magnetic components do not need to be designed for the most stringent scenarios of low frequency, full power, and full voltage range, which helps to reduce reactor size, copper and iron usage, and bill of materials costs.

[0072] S250: Perform frequency switching management on the target switching frequency and update the pulse width modulation output of the bidirectional DC-DC converter based on the result of the frequency switching management.

[0073] In one specific embodiment, taking the discharge condition as an example, this describes one implementation of setting the frequency and current limiting strategy according to the battery voltage zone, which is not intended to limit the scope of protection of this invention.

[0074] For example, a first voltage threshold Vd1 = 250V is set in the low-voltage current-limiting region. When the battery-side voltage Vbat rises to no less than Vd1 + 5V (i.e., 255V), and the duration of this voltage state is no less than 100ms, the maximum current limit is narrowed from 180A to 168A; when Vbat drops to no more than Vd1 - 5V (i.e., 245V), and the duration of this voltage state is no less than 10ms, the maximum current limit is restored from 168A to 180A. By setting a 5V hysteresis interval and asymmetric hold time (100ms for tightening during boost and 10ms for relaxing during buck), the repeated switching of the current-limiting level due to voltage sampling fluctuations at the low-voltage boundary can be effectively avoided.

[0075] In the medium-voltage frequency conversion zone, a second voltage threshold Vd2 is set to 340V. When Vbat rises to no less than Vd2+5V (i.e., 345V) and the duration T is no less than 100ms, the BDC switching frequency switches from 16kHz to 24kHz; when Vbat drops to no more than Vd2-5V (i.e., 335V) and the duration T is no less than 100ms, the BDC switching frequency switches back from 24kHz to 16kHz. By increasing the switching frequency in the medium-voltage high-ripple or high-loss sensitive region, inductor current ripple can be effectively reduced, and system efficiency optimized.

[0076] In the high-voltage cutoff region, a third voltage threshold Vd3 is set to 560V. When Vbat rises to no less than Vd3+5V (i.e., 565V) and the duration T is no less than 100ms, the BDC switching frequency cuts back from 24kHz to 16kHz; when Vbat drops to no more than Vd3-5V (i.e., 555V) and the duration T is no less than 100ms, the BDC switching frequency recovers from 16kHz to 24kHz. The current in the high-voltage region naturally decreases, and both device losses and inductor ripple meet the requirements, thus allowing a return to a lower switching frequency to reduce switching losses.

[0077] It should be noted that the voltage threshold, hysteresis voltage, hold-up time, current limit value, and frequency range mentioned above are all exemplary parameters. In actual projects, they can be flexibly calibrated according to the battery pack voltage range, DC bus voltage, rated power, power device selection, and actual measurement results. This embodiment does not constitute a limitation on the specific values ​​of the above parameters.

[0078] It should be noted that the above thresholds are examples. In actual projects, each parameter (Vd1 / Vd2 / Vd3, hysteresis voltage, hold-up time, current limit value, frequency range) can be calibrated according to the battery pack range, bus voltage, rated power, device selection and test results.

[0079] Due to the complexity of operating conditions in practical applications, it is difficult to exhaustively verify each item. Therefore, this embodiment employs a three-point envelope method to check the critical boundaries. The three-point envelope method uses the highest bus voltage, the lowest bus voltage, and the rated bus voltage as three verification points, respectively covering the switching loss boundary, the conduction loss boundary, and the system efficiency benchmark, as detailed below: The first verification point is the highest bus voltage (e.g., 950V). This verification point corresponds to the extreme switching loss condition. The focus is on verifying whether the junction temperature, thermal stress, and EMC margin of the power devices meet the design requirements under the highest dv / dt conditions and at higher switching frequencies.

[0080] The second verification point is the minimum bus voltage (e.g., 650V). This verification point corresponds to the extreme conduction loss condition. The focus is on verifying whether the inductor saturation margin, device conduction losses, and system-level heat dissipation extremes meet the design requirements under low-frequency, high-current conditions.

[0081] The third verification point: rated bus voltage (e.g., 850V). This verification point serves as the system energy efficiency benchmark. The focus is on evaluating the comprehensive improvement effect of the frequency converter control strategy on annual weighted efficiency, all-condition loss distribution, and thermal design margin.

[0082] The technical solution of this application embodiment dynamically determines the target switching frequency from a set of candidate switching frequencies based on operating parameters. This makes the decision-making basis for the switching frequency no longer a single voltage or current index, but a comprehensive optimal choice made after considering multiple operating parameters. As a result, a more suitable switching frequency can be selected under different voltage, current, power direction, and temperature conditions, reducing ineffective losses and improving overall operating efficiency. Furthermore, by identifying the current operating condition, calculating multi-dimensional constraint indicators for each candidate switching frequency, eliminating candidate frequencies that do not meet the hard safety constraints, and comprehensively scoring the remaining candidate frequencies to determine the target switching frequency, adaptive switching frequency decision-making based on multiple constraints is achieved. Because the frequency decision comprehensively considers seven dimensions of constraints, including power device losses, magnetic component ripple and saturation, core and winding temperature rise, bus capacitor ripple current, EMC risk, control and sampling margin, and protection margin, and comprehensively scores efficiency, temperature rise, ripple, electromagnetic compatibility, and power density under the premise of satisfying the hard safety constraints, it can select the optimal switching frequency under different operating conditions. This ensures system safety while taking into account multiple performance requirements such as efficiency, heat dissipation, ripple quality, electromagnetic compatibility, and power density, overcoming the shortcomings of existing solutions that rely on a single frequency modulation basis and cannot achieve comprehensive optimization.

[0083] Example 3 Figure 3 This is a schematic diagram of the switching frequency switching device for a bidirectional DC-DC converter provided in Embodiment 3 of this application. Figure 3 As shown, the device includes: a parameter acquisition module 310, a frequency determination module 320, and a frequency switching module 330; Parameter acquisition module 310 is used to acquire the operating parameters of the bidirectional DC-DC converter; The frequency determination module 320 is used to determine the target switching frequency from the candidate switching frequency set based on the operating parameters; The frequency switching module 330 is used to perform frequency switching management on the switching of the target switching frequency, and update the pulse width modulation output of the bidirectional DC-DC converter according to the result of the frequency switching management; the frequency switching management includes at least one of hysteresis interval management, minimum hold time management and soft switching management.

[0084] Optionally, the hysteresis interval management means that when at least one of the operating parameters reaches a preset switching threshold, there is a hysteresis interval between a first switching threshold for switching from the current switching frequency to the target switching frequency and a second switching threshold for switching back from the target switching frequency to the current switching frequency. The minimum hold time management means that frequency switching is only allowed after the current switching frequency or the target switching frequency has been running stably for a preset time. The soft switching management involves gradually adjusting the current switching frequency to the target switching frequency using a segmented transition method or a slope limiting method when the difference between the target switching frequency and the current switching frequency exceeds a preset rate of change limit.

[0085] Optionally, the frequency switching management further includes: abnormal rollback management; The abnormal rollback management involves switching the current switching frequency to a preset safe frequency or performing derating operation or protection actions when an abnormality is detected.

[0086] Optionally, the hysteresis interval management includes voltage hysteresis interval management and / or current hysteresis interval management; The voltage hysteresis interval management is as follows: When the voltage rises to a level not less than the sum of the first voltage threshold and the preset hysteresis voltage, a frequency upsampling switch is performed to switch from the current switching frequency to the target switching frequency. When the voltage drops to a value no greater than the difference between the first voltage threshold and the preset hysteresis voltage, a frequency reduction switching is performed to switch from the current switching frequency to the target switching frequency. When the voltage is within a range that is greater than the difference between the first voltage threshold and the preset hysteresis voltage, and less than the sum of the first voltage threshold and the preset hysteresis voltage, the current switching frequency is maintained unchanged. The current hysteresis interval management is as follows: When the current rises to a level not less than the sum of the first current threshold and the preset hysteresis current, a frequency upswitching switch is performed, switching from the current switching frequency to the target switching frequency corresponding to the first current threshold. When the current drops to no more than the difference between the first current threshold and the preset hysteresis current, a frequency reduction switching is performed to switch from the current switching frequency to the target switching frequency. When the current is within a range that is greater than the difference between the first current threshold and the preset hysteresis current, and less than the sum of the first current threshold and the preset hysteresis current, the current switching frequency is maintained unchanged.

[0087] Optionally, the frequency determination module 320 includes: The operating condition determination unit is used to identify the current operating condition of the bidirectional DC-DC converter based on the operating parameters. The constraint index calculation unit is used to calculate the calculation result of each candidate switching frequency in the candidate switching frequency set under the multi-dimensional constraint index. The frequency determination unit is used to determine the target switching frequency from the candidate switching frequency set based on the calculation results of the multi-dimensional constraint indicators under the current operating conditions.

[0088] Optionally, the multi-dimensional constraint indicators include at least one of the following: Power device loss constraints, magnetic component ripple and saturation constraints, core and winding losses and temperature rise constraints, bus capacitor ripple current constraints, electromagnetic compatibility risk constraints, control and sampling margin constraints, and protection margin constraints.

[0089] Optionally, the frequency determination unit is specifically used for: Candidate switching frequencies that do not meet the safety hard constraints are removed from the candidate switching frequency set; the safety hard constraints include at least one of the following: the saturation margin of the magnetic element is lower than a preset threshold, the junction temperature of the power device exceeds a preset limit, and the ripple current of the bus capacitor exceeds a preset limit. The remaining candidate switching frequencies are comprehensively scored using multi-dimensional scoring indicators, and the target switching frequency is determined based on the scoring results. The multi-dimensional scoring indicators include at least one of the following: efficiency, temperature rise, ripple, electromagnetic compatibility, and power density.

[0090] Optionally, the operating parameters include voltage, current, output power, power direction, power device temperature, magnetic component temperature, and operating mode.

[0091] The switching frequency switching device for the bidirectional DC-DC converter provided in this application embodiment can execute the switching frequency switching method for the bidirectional DC-DC converter provided in any embodiment of this application, and has the corresponding functional modules and beneficial effects of executing the method.

[0092] Example 4 Figure 4 A schematic diagram of an electronic device 10, which can be used to implement embodiments of this application, is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (such as helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the application described and / or claimed herein.

[0093] like Figure 4 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 can also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0094] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0095] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as the switching frequency switching method of a bidirectional DC-DC converter.

[0096] In some embodiments, the switching frequency switching method of the bidirectional DC-DC converter can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the switching frequency switching method of the bidirectional DC-DC converter described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the switching frequency switching method of the bidirectional DC-DC converter by any other suitable means (e.g., by means of firmware).

[0097] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations may include: implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0098] In some embodiments, the switching frequency switching method of the bidirectional DC-DC converter can be implemented as a computer program, which is implicitly included in a computer program product. When executed by a processor, the computer program implements the switching frequency switching method of the bidirectional DC-DC converter of this application. The computer program product can be understood as a software product that primarily implements its solution through a computer program. The computer program used to implement the method of this application can be written in any combination of one or more programming languages. These computer programs can be provided to the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the functions / operations specified in the flowcharts and / or block diagrams are implemented. The computer program can be executed entirely on a machine, partially on a machine, partially on a remote machine as a standalone software package, or entirely on a remote machine or server.

[0099] In the context of this application, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium can be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0100] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0101] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or middleware components (e.g., application servers), or frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0102] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0103] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this application can be achieved, and this is not limited herein.

[0104] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for switching the switching frequency of a bidirectional DC-DC converter, characterized in that, include: Collect operating parameters of the bidirectional DC-DC converter; The target switching frequency is determined from the candidate switching frequency set based on the operating parameters. Frequency switching management is performed on the switching of the target switching frequency, and the pulse width modulation output of the bidirectional DC-DC converter is updated according to the result of the frequency switching management; the frequency switching management includes at least one of hysteresis interval management, minimum hold time management and soft switching management.

2. The method according to claim 1, characterized in that, The hysteresis interval management means that when at least one of the operating parameters reaches a preset switching threshold, there is a hysteresis interval between the first switching threshold for switching from the current switching frequency to the target switching frequency and the second switching threshold for switching back from the target switching frequency to the current switching frequency.

3. The method according to claim 2, characterized in that, The hysteresis interval management includes voltage hysteresis interval management and / or current hysteresis interval management; The voltage hysteresis interval management is as follows: When the voltage rises to a level not less than the sum of the first voltage threshold and the preset hysteresis voltage, a frequency upsampling switch is performed to switch from the current switching frequency to the target switching frequency. When the voltage drops to a value no greater than the difference between the first voltage threshold and the preset hysteresis voltage, a frequency reduction switching is performed to switch from the current switching frequency to the target switching frequency. When the voltage is within a range that is greater than the difference between the first voltage threshold and the preset hysteresis voltage, and less than the sum of the first voltage threshold and the preset hysteresis voltage, the current switching frequency is maintained unchanged. The current hysteresis interval management is as follows: When the current rises to a level not less than the sum of the first current threshold and the preset hysteresis current, a frequency upswitching switch is performed, switching from the current switching frequency to the target switching frequency corresponding to the first current threshold. When the current drops to no more than the difference between the first current threshold and the preset hysteresis current, a frequency reduction switching is performed to switch from the current switching frequency to the target switching frequency. When the current is within a range that is greater than the difference between the first current threshold and the preset hysteresis current, and less than the sum of the first current threshold and the preset hysteresis current, the current switching frequency is maintained unchanged.

4. The method according to claim 1, characterized in that, The minimum hold time management means that frequency switching is only allowed after the current switching frequency or the target switching frequency has been running stably for a preset time.

5. The method according to claim 1, characterized in that, The soft switching management involves gradually adjusting the current switching frequency to the target switching frequency using a segmented transition method or a slope limiting method when the difference between the target switching frequency and the current switching frequency exceeds a preset rate of change limit.

6. The method according to claim 1, characterized in that, The frequency switching management also includes: abnormal rollback management; The abnormal rollback management involves switching the current switching frequency to a preset safe frequency or performing derating operation or protection actions when an abnormality is detected.

7. The method according to claim 1, characterized in that, The step of determining the target switching frequency from the candidate switching frequency set based on the operating parameters includes: The current operating condition of the bidirectional DC-DC converter is identified based on the operating parameters. For each candidate switching frequency in the candidate switching frequency set, calculate the calculation result of the candidate switching frequency under the multi-dimensional constraint index; Under the current operating conditions, the target switching frequency is determined from the candidate switching frequency set based on the calculation results of the multi-dimensional constraint indicators.

8. The method according to claim 7, characterized in that, The multi-dimensional constraint indicators include at least one of the following: Power device loss constraints, magnetic component ripple and saturation constraints, core and winding losses and temperature rise constraints, bus capacitor ripple current constraints, electromagnetic compatibility risk constraints, control and sampling margin constraints, and protection margin constraints.

9. The method according to claim 8, characterized in that, Determining the target switching frequency from the candidate switching frequency set based on the calculation results of the multi-dimensional constraint indicators includes: Candidate switching frequencies that do not meet the safety hard constraints are removed from the candidate switching frequency set; the safety hard constraints include at least one of the following: the saturation margin of the magnetic element is lower than a preset threshold, the junction temperature of the power device exceeds a preset limit, and the ripple current of the bus capacitor exceeds a preset limit. The remaining candidate switching frequencies are comprehensively scored using multi-dimensional scoring indicators, and the target switching frequency is determined based on the scoring results. The multi-dimensional scoring indicators include at least one of the following: efficiency, temperature rise, ripple, electromagnetic compatibility, and power density.

10. The method according to claim 1, characterized in that, The operating parameters include voltage, current, output power, power direction, power device temperature, magnetic component temperature, and operating mode.

11. A switching frequency switching device for a bidirectional DC-DC converter, characterized in that, include: The parameter acquisition module is used to acquire the operating parameters of the bidirectional DC-DC converter. A frequency determination module is used to determine a target switching frequency from a set of candidate switching frequencies based on the operating parameters; The frequency switching module is used to perform frequency switching management on the switching of the target switching frequency, and update the pulse width modulation output of the bidirectional DC-DC converter according to the result of the frequency switching management; the frequency switching management includes at least one of hysteresis interval management, minimum hold time management and soft switching management.

12. An electronic device, characterized in that, The electronic device includes: At least one processor; and a memory communicatively connected to the at least one processor; The memory stores a computer program that can be executed by the at least one processor, which is then executed by the at least one processor to enable the at least one processor to perform the switching frequency switching method of the bidirectional DC-DC converter according to any one of claims 1-10.

13. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that, when executed by a processor, implement the switching frequency switching method of the bidirectional DC-DC converter according to any one of claims 1-10.

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