Switching frequency control method, system, apparatus, device, medium, and product

Abstract

This invention relates to the field of power electronic device testing and power semiconductor reliability testing technology, and discloses a switching frequency control method, system, device, equipment, medium, and product. The method includes: obtaining a target switching frequency; determining an integer carrier ratio and a modulation wave frequency based on a preset allowable range of modulation wave frequency, such that the product of the integer carrier ratio and the modulation wave frequency equals the target switching frequency, and the modulation wave frequency is within the allowable range; generating a sinusoidal modulation wave based on the modulation wave frequency, and generating a triangular carrier wave based on the target switching frequency, wherein the ratio of the frequency of the triangular carrier wave to the frequency of the sinusoidal modulation wave is maintained as an integer carrier ratio; comparing the sinusoidal modulation wave and the triangular carrier wave, generating a switching drive signal based on the comparison result, and driving the IGBT submodule based on the switching drive signal. This invention solves the problem that the switching frequency under synchronous modulation can only be an integer multiple of the power frequency and cannot be continuously adjusted to an integer within a wide range, while asynchronous modulation will generate subharmonics.

Description

Technical Field

[0001] This invention relates to the field of power electronic device testing and power semiconductor reliability testing technology, specifically to switching frequency control methods, systems, devices, equipment, media, and products. Background Technology

[0002] In IGBT power cycling tests, the switching frequency needs to be continuously and arbitrarily set within the range of 50Hz to 1000Hz. In existing SPWM (Sinusoidal Pulse Width Modulation) schemes, synchronous modulation requires maintaining an integer ratio between the carrier frequency and the modulation wave frequency. When the modulation wave frequency is fixed at the power frequency, the switching frequency can only be an integer multiple of the power frequency, making it impossible to achieve non-integer multiples such as 210Hz or 235Hz. While asynchronous modulation can achieve arbitrary frequencies, it generates subharmonics, leading to distortion of the output voltage waveform. Furthermore, existing schemes experience voltage and current surges during frequency switching, modulation wave jitter near the current zero-crossing point, and inconsistent voltage equalization performance at different frequencies. Summary of the Invention

[0003] This invention provides a switching frequency control method, system, device, equipment, medium, and product to solve the problems that the switching frequency under existing synchronous modulation can only be an integer multiple of the power frequency and cannot be continuously adjusted to an integer within a wide range, while asynchronous modulation will generate subharmonics.

[0004] In a first aspect, the present invention provides a switching frequency control method applied to a power cycling test circuit, the method comprising: Obtain the target switching frequency; Based on the preset allowable range of modulation wave frequency, determine the integer carrier ratio and modulation wave frequency, so that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range. A sinusoidal modulated wave is generated based on the modulation wave frequency, and a triangular carrier wave is generated based on the target switching frequency, wherein the ratio of the frequency of the triangular carrier wave to the frequency of the sinusoidal modulated wave is maintained as an integer carrier ratio. The sinusoidal modulated wave is compared with the triangular carrier wave, and a switching drive signal is generated based on the comparison result. The IGBT sub-module in the power cycle test circuit is then driven based on the switching drive signal.

[0005] This invention provides a switching frequency control method that dynamically adjusts the modulation wave frequency instead of fixing it to the power frequency, allowing the switching frequency to be precisely set to any integer frequency within the allowable range. This breaks through the limitation of traditional synchronous modulation, which can only take integer multiples of the power frequency. At the same time, it maintains an integer carrier ratio, avoiding subharmonics generated by asynchronous modulation. Thus, it achieves a wide range of continuous integer frequency settings while ensuring the quality of the output voltage waveform. This solves the problem that the switching frequency under existing synchronous modulation can only take integer multiples of the power frequency and cannot be continuously adjusted to an integer within a wide range, while asynchronous modulation generates subharmonics.

[0006] In one optional implementation, determining the integer carrier ratio and the modulation frequency based on a preset allowable range of the modulation wave frequency includes: Iterate through the integer carrier ratio values ​​and calculate the modulation wave frequency corresponding to each value; Filter the integer carrier ratio to keep the modulation wave frequency within the allowable range; If multiple integer carrier ratios are selected, choose the integer carrier ratio that minimizes the absolute value of the difference between the modulation wave frequency and the preset power frequency.

[0007] In the above technical solution, by traversing all possible integer carrier ratios and filtering values ​​that make the modulation wave frequency fall within the allowable range, the target switching frequency is fully covered without omission. When there are multiple feasible carrier ratios, the value that makes the modulation wave frequency closest to the power frequency is selected first, thereby minimizing the impact of the modulation wave frequency deviating from the power frequency on the electrical parameters of the load and filter circuits, so that the system works in a relatively optimal modulation state.

[0008] In one alternative implementation, the method further includes: When the target switching frequency changes, the frequency of the triangular carrier and the frequency of the sinusoidal modulation wave are adjusted at a preset gradual rate until the carrier frequency and modulation wave frequency corresponding to the changed target switching frequency are reached.

[0009] In the above technical solution, by gradually adjusting the carrier frequency and modulation wave frequency at a preset gradual rate instead of directly jumping, the voltage and current surges caused by frequency abrupt changes are avoided, so that the power cycle test circuit can maintain stable operation during frequency switching, ensuring the continuity of thermal stress on the device and the safety of the test during the switching period.

[0010] In one optional implementation, adjusting the frequency of the triangular carrier wave and the frequency of the sinusoidal modulation wave at a preset gradual rate includes: If the integer carrier ratio remains unchanged, the modulation wave frequency is adjusted from the current value to the new value at a preset gradual rate, and the carrier frequency corresponds to the target switching frequency. If the integer carrier ratio changes, first keep the current modulation wave frequency unchanged, adjust the carrier frequency at a preset gradual rate to the carrier frequency corresponding to the changed integer carrier ratio, and then adjust the modulation wave frequency at a preset gradual rate to the new value.

[0011] In the above technical solution, the switching strategy only needs to adjust the modulation wave frequency when the carrier ratio remains unchanged. The carrier automatically follows the target switching frequency change, and the switching process is simple and always keeps synchronized. When the carrier ratio changes, it is executed in steps: first, the modulation wave frequency is kept unchanged and the carrier frequency is adjusted to the value corresponding to the new carrier ratio, and then the modulation wave frequency is adjusted to the target value. This avoids the risk of frequency relationship disorder caused by adjusting two frequencies at the same time, and ensures the controllability and stability of the entire switching process.

[0012] In an alternative implementation, the method further includes, before comparing the sinusoidal modulated wave with the triangular carrier wave: Collect the current in the power cycle test circuit; When the absolute value of the current is greater than or equal to a preset threshold, the sign of the duty cycle correction is determined based on the current direction, and the duty cycle correction is calculated based on the sign. When the absolute value of the current is less than a preset threshold, the sign of the current direction before entering the interval less than or equal to the preset threshold remains unchanged, and the duty cycle correction is calculated based on the maintained sign of the current direction. The sinusoidal modulation wave or comparison result is corrected based on the duty cycle correction.

[0013] In the above technical solution, by determining the sign of the duty cycle correction amount based on the actual current direction when the absolute value of the current is greater than the preset threshold, and keeping the sign of the current direction before entering the interval unchanged when the absolute value of the current is less than the preset threshold, the alternating positive and negative jitter of the correction amount caused by frequent direction jumps near the current zero crossing point is avoided, so that the duty cycle correction amount is smoothly transitioned, thereby ensuring the stability of the submodule voltage balance.

[0014] In one alternative implementation, the method further includes: Based on the ratio of the current carrier frequency to the preset reference carrier frequency, the proportional coefficient and integral coefficient of the equalization control are adjusted proportionally, and the adjusted proportional coefficient and integral coefficient are used to calculate the duty cycle correction.

[0015] In the above technical solution, the proportional coefficient and integral coefficient of the voltage equalization control are adjusted in real time according to the ratio of the current carrier frequency to the reference carrier frequency, so that the voltage equalization control parameters are adaptively updated as the switching frequency changes. This avoids the problem of control loop characteristic deviation caused by fixed parameters at different frequencies, thereby maintaining the consistency and adaptability of voltage equalization control performance across the entire frequency range.

[0016] In one alternative implementation, the method further includes: The maximum allowable duty cycle adjustment limit is adjusted proportionally within each switching cycle based on the ratio. The adjusted maximum duty cycle adjustment limit is used to constrain the range of values ​​for the duty cycle correction.

[0017] In the above technical solution, the maximum duty cycle adjustment limit is adjusted in real time according to the ratio of the carrier frequency to the reference frequency, so that the limit range changes synchronously with the switching frequency. This avoids the problems of over-adjustment caused by excessive adjustment step size at low frequencies and insufficient response caused by limited adjustment step size at high frequencies. Thus, the adjustment range of the duty cycle correction is matched with the switching cycle across the entire frequency range, ensuring the dynamic performance of voltage equalization control.

[0018] Secondly, this invention provides a switching frequency control system applied to a power cycling test circuit. The switching frequency control system includes: a host computer, a control and protection subsystem, a valve base controller, and a sub-module drive circuit, wherein: The host computer is used to send the target switching frequency to the control and protection subsystem; The control and protection subsystem is used to acquire the target switching frequency; based on the preset allowable range of the modulation wave frequency, it determines the integer carrier ratio and the modulation wave frequency, so that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range, and sends the integer carrier ratio and the modulation wave frequency to the valve base controller; The valve base controller is used to generate a sinusoidal modulated wave based on the modulation wave frequency and a triangular carrier based on the target switching frequency, and the ratio of the frequency of the triangular carrier to the frequency of the sinusoidal modulated wave is kept as an integer carrier ratio; the sinusoidal modulated wave is compared with the triangular carrier, a switching drive signal is generated based on the comparison result, and the switching drive signal is sent to the submodule drive circuit; The submodule drive circuit is used to drive the IGBT submodule in the power cycle test circuit based on the switch drive signal.

[0019] Thirdly, the present invention provides a switching frequency control device for use in a power cycling test circuit, the device comprising: The parameter configuration module is used to obtain the target switching frequency; The frequency calculation module is used to determine the integer carrier ratio and the modulation wave frequency based on the preset allowable range of the modulation wave frequency, so that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range. The signal generation module is used to generate a sinusoidal modulated wave based on the modulation wave frequency and a triangular carrier based on the target switching frequency, and the ratio of the frequency of the triangular carrier to the frequency of the sinusoidal modulated wave is kept as an integer carrier ratio; the sinusoidal modulated wave and the triangular carrier are compared, a switching drive signal is generated based on the comparison result, and the IGBT sub-module in the power cycle test circuit is driven based on the switching drive signal.

[0020] Fourthly, the present invention provides an electronic device, comprising: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the switching frequency control method of the first aspect or any corresponding embodiment described above.

[0021] Fifthly, the present invention provides a computer-readable storage medium storing computer instructions for causing a computer to execute the switching frequency control method of the first aspect or any corresponding embodiment thereof.

[0022] In a sixth aspect, the present invention provides a computer program product, including computer instructions for causing a computer to execute the switching frequency control method of the first aspect or any corresponding embodiment thereof. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a switching frequency control system according to an embodiment of the present invention; Figure 2 This is a schematic flowchart of a first method for controlling the switching frequency according to an embodiment of the present invention; Figure 3 This is a second flowchart illustrating the switching frequency control method according to an embodiment of the present invention; Figure 4 This is a topology diagram of the main circuit of the power cycling test loop according to an embodiment of the present invention; Figure 5 This is a schematic diagram of carrier phase shift control for a single IGBT submodule according to an embodiment of the present invention; Figure 6 This is a structural block diagram of a switching frequency control device according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0027] As an optional application scenario of this invention, such as Figure 1 As shown, this invention provides a switching frequency control system applied to a power cycling test circuit 150. The main circuit of the power cycling test circuit includes a DC charging power supply, an auxiliary valve, a test valve, and a load inductor. The auxiliary valve and the test valve are each composed of three IGBT sub-modules. The DC charging power supply is used for charging during test startup and for replenishing circuit losses during the test. By adjusting the phase angle difference of the modulation waves of the auxiliary valve and the test valve, current is generated in the circuit, and a specified thermal stress is applied to the IGBT module under test in the test valve.

[0028] The switching frequency control system includes: a host computer 110, a control and protection subsystem 120, a valve base controller 130, and a sub-module drive circuit 140, wherein: The host computer 110 is used to send the target switching frequency to the control and protection subsystem; The control and protection subsystem 120 is used to acquire the target switching frequency; based on the allowable range of the preset modulation wave frequency, it determines the integer carrier ratio and the modulation wave frequency, so that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range, and sends the integer carrier ratio and the modulation wave frequency to the valve base controller. The valve base controller 130 is used to generate a sinusoidal modulation wave based on the modulation wave frequency and generate a triangular carrier based on the target switching frequency, and the ratio of the frequency of the triangular carrier to the frequency of the sinusoidal modulation wave is kept as an integer carrier ratio; the sinusoidal modulation wave is compared with the triangular carrier, a switching drive signal is generated based on the comparison result, and the switching drive signal is sent to the submodule drive circuit; The submodule drive circuit 140 is used to drive the IGBT submodule in the power cycle test loop based on the switch drive signal.

[0029] The switching frequency control system also includes a current / voltage measurement unit 160, which is used to acquire the current and voltage signals of the power cycle test circuit and feed the acquired current and voltage signals back to the control and protection subsystem.

[0030] The control and protection subsystem embeds the following functional modules: a variable modulation wave frequency synchronization modulation module, a frequency smoothing switching module, a zero-crossing duty cycle correction smoothing module, a switching frequency adaptive voltage equalization parameter tuning module, and a CPS-SPWM (Carrier Phase Shifted Sinusoidal Pulse Width Modulation) trigger signal generation module. Among them: The variable modulation wave frequency synchronization modulation module receives the user-defined target switching frequency (any integer from 50 to 1000 Hz) and searches for a suitable integer carrier ratio N and modulation wave frequency f within a preset allowable modulation wave frequency range (e.g., 40 to 60 Hz). m , so that N×f m It is exactly equal to the target switching frequency, and the modulation wave frequency f m Within the permissible range. Then, at the modulation wave frequency f... m A sinusoidal modulation wave is generated, and a triangular carrier wave is generated at the target switching frequency. The carrier ratio is kept to an integer N to achieve synchronous modulation, and the output voltage has no harmonics.

[0031] The frequency smooth switching module is used to control the carrier frequency and / or modulation wave frequency to gradually transition to the new frequency at a preset gradual rate (such as carrier frequency 10Hz / ms, modulation wave frequency 1Hz / s) when the target switching frequency is changed online, rather than jumping directly.

[0032] The zero-crossing duty cycle correction smoothing module is used to keep the current direction sign unchanged before entering the current range when the current direction signal is unreliable near the current zero-crossing point (|i|≤ threshold, the threshold is usually 2% to 5% of the rated current), thus avoiding positive and negative jumps in the correction amount and eliminating modulation wave jitter.

[0033] The switching frequency adaptive voltage equalization parameter tuning module is used to adjust the proportional coefficient, integral coefficient, and correction limit value in real time according to the ratio of the current carrier frequency to the reference carrier frequency, so that the voltage equalization control performance remains consistent under different switching frequencies.

[0034] The CPS-SPWM trigger signal generation module is used to send a sinusoidal modulated wave and a triangular carrier wave into a comparator to generate a PWM (Pulse Width Modulation) pulse sequence; at the same time, it assigns different initial phases to the carrier waves of the IGBT sub-modules in the auxiliary valve and the test valve (the three sub-modules are 120° out of phase with each other), generating corresponding upper and lower trigger signals, which are then used by the drive circuit to control the IGBT switching on and off.

[0035] According to an embodiment of the present invention, a switching frequency control method embodiment is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0036] This embodiment provides a switching frequency control method that can be used in power cycling test circuits. Figure 2 This is a flowchart of a switching frequency control method according to an embodiment of the present invention, such as... Figure 2 As shown, the process includes the following steps: Step S201: Obtain the target switching frequency.

[0037] Among them, the target switching frequency is the core parameter that determines the thermal stress of the IGBT device in the power cycling test. It refers to the actual switching frequency (i.e., carrier frequency) applied to the IGBT device. Its value needs to be continuously adjustable in integers within the range of 50Hz to 1000Hz (such as 210Hz, 235Hz, etc.) to adapt to different test standards and device specifications. This frequency is predetermined by the test requirements. After being set by inputting the setting into the host computer human-machine interface, it is sent to the control and protection subsystem as the input command for the entire control method.

[0038] Step S202: Based on the preset allowable range of modulation wave frequency, determine the integer carrier ratio and modulation wave frequency, so that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range.

[0039] The preset modulation wave frequency is a sinusoidal modulation wave frequency calculated by the control and protection subsystem in reverse based on the target switching frequency. Its allowable range is preset (e.g., 40Hz to 60Hz). Within this range, the frequency value is dynamically selected so that the product of the integer carrier ratio and the modulation wave frequency is exactly equal to the target switching frequency.

[0040] The integer carrier ratio is the ratio of the triangular carrier frequency (i.e., the target switching frequency) to the sinusoidal modulation wave frequency, and this ratio must be a positive integer. In this embodiment, the integer carrier ratio is not a fixed value, but is dynamically calculated and determined by the control and protection subsystem based on the target switching frequency within the preset modulation wave frequency allowable range. This ensures that the target switching frequency and the modulation wave frequency satisfy the relationship that the target switching frequency = integer carrier ratio × modulation wave frequency is an integer multiple of the target switching frequency, thereby achieving continuous integer frequency setting while maintaining synchronous modulation to eliminate subharmonics.

[0041] Step S203: Generate a sinusoidal modulated wave based on the modulation wave frequency, and generate a triangular carrier based on the target switching frequency, wherein the ratio of the frequency of the triangular carrier to the frequency of the sinusoidal modulated wave is maintained as an integer carrier ratio.

[0042] Specifically, the calculated modulation wave frequency and target switching frequency are sent to the valve base controller. The valve base controller generates a sinusoidal modulation wave with the modulation wave frequency and a triangular carrier wave with the target switching frequency, and makes the ratio of their frequencies equal to the determined integer carrier ratio. Then, the sine wave and the triangular wave are compared in real time. When the instantaneous value of the sine wave is higher than that of the triangular wave, a high level is output, and when it is lower than that of the triangular wave, a low level is output, thereby generating the corresponding PWM pulse sequence.

[0043] Step S204: Compare the sinusoidal modulated wave with the triangular carrier wave, generate a switching drive signal based on the comparison result, and drive the IGBT sub-module in the power cycle test circuit based on the switching drive signal.

[0044] Specifically, the valve base controller sends a sinusoidal modulated wave and a triangular carrier wave to a comparator for real-time comparison. When the instantaneous value of the sinusoidal wave is higher than that of the triangular wave, it outputs a high level; when it is lower than that of the triangular wave, it outputs a low level, generating the original PWM pulse sequence corresponding to the target switching frequency. At the same time, the valve base controller allocates carrier waves with an initial phase difference of 120° to each IGBT sub-module in the auxiliary valve and test valve in the power cycle test loop according to the CPS-SPWM strategy, generating trigger pulses for the upper and lower transistors of each sub-module respectively. These pulses are then sent to the drive circuit of each sub-module via optical fiber or cable. After isolation and amplification by the drive circuit, the switching on and off of each IGBT sub-module is controlled, thereby generating the required test current in the loop.

[0045] The switching frequency control method provided in this embodiment dynamically adjusts the modulation wave frequency instead of fixing it to the power frequency, so that the switching frequency can be precisely set to any integer frequency within the allowable range, breaking through the limitation of traditional synchronous modulation that can only be an integer multiple of the power frequency; at the same time, it maintains an integer carrier ratio, avoiding subharmonics generated by asynchronous modulation, thereby ensuring the quality of the output voltage waveform while achieving a wide range of continuous integer frequency settings.

[0046] This embodiment provides a switching frequency control method that can be used in power cycling test circuits. Figure 3 This is a flowchart of a switching frequency control method according to an embodiment of the present invention, such as... Figure 3 As shown, the process includes the following steps: Step S301: Obtain the target switching frequency. For details, please refer to [link to relevant documentation]. Figure 2 Step S201 of the illustrated embodiment will not be described again here.

[0047] Step S302: Based on the preset allowable range of modulation wave frequency, determine the integer carrier ratio and modulation wave frequency, so that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range.

[0048] Specifically, this step belongs to the process of a synchronous modulation strategy with variable modulation wave frequency (core: achieving continuous integer frequency without subharmonics). The core of this strategy is: instead of fixing the modulation wave frequency, it dynamically selects a suitable integer carrier ratio based on the target switching frequency set by the user. and modulation wave frequency , making The frequency is exactly equal to the integer frequency set by the user, and It is limited to the allowable range (e.g., 40Hz~60Hz) to simultaneously meet the two objectives of "integer carrier ratio (no subharmonics)" and "continuous integer frequency".

[0049] Step S302 above includes: Step S3021: Iterate through the integer carrier ratio values ​​and calculate the modulation wave frequency corresponding to each value.

[0050] Specifically, let the user's desired target switching frequency be... (Range 50Hz to 1000Hz). Set the allowable range of variation for the modulation wave frequency. , (The preferred value is 40Hz to 60Hz).

[0051] Step S3022: Filter integer carrier ratios that keep the modulation wave frequency within the allowable range.

[0052] Specifically, for a given target switching frequency The system searches for all possible integer carrier ratios. ( ), calculate the corresponding modulation wave frequency Filter out those that meet the requirements of Value set.

[0053] Step S3023: If multiple integer carrier ratios are selected, choose the integer carrier ratio that minimizes the absolute value of the difference between the modulation wave frequency and the preset power frequency.

[0054] Specifically, if there are multiple feasible integer carrier ratios Select the modulation wave frequency Integer carrier ratio closest to the power frequency of 50Hz To minimize the impact of modulation frequency deviation on the load. If no feasible integer carrier ratio exists. If the target switching frequency set by the user is out of range, the system will prompt the user and recommend the closest achievable frequency.

[0055] Step S303: Generate a sinusoidal modulation wave based on the modulation wave frequency, and generate a triangular carrier based on the target switching frequency, wherein the ratio of the frequency of the triangular carrier to the frequency of the sinusoidal modulation wave is maintained as an integer carrier ratio.

[0056] Specifically, determine the integer carrier ratio and modulation wave frequency Then, the system sets the frequency of the triangular carrier wave to... (equal to target switching frequency) The frequency of the sinusoidal modulation wave is set as the modulation wave frequency. and maintain carrier ratio The integer value enables synchronous modulation, resulting in an output voltage without harmonics.

[0057] Due to the frequency of the modulation wave It can vary continuously within a certain range, and the carrier ratio Different integers can be taken to make the triangular carrier wave... It can cover all integer frequencies in the range of 50Hz to 1000Hz. For example: To set the target switching frequency to 210Hz: take the carrier ratio. Then it is necessary It can accurately achieve 210Hz.

[0058] To set the target switching frequency to 199Hz: take the carrier ratio. Modulation wave frequency ; or carrier ratio Modulation wave frequency (Exceeding the lower limit of the preset modulation wave frequency range by 40Hz), therefore, take... , .

[0059] This strategy enables precise setting of the switching frequency with full integer frequency coverage and no subharmonics.

[0060] Step S304: When the target switching frequency changes, the frequency of the triangular carrier and the frequency of the sinusoidal modulation wave are adjusted at a preset gradual rate until the carrier frequency and modulation wave frequency corresponding to the changed target switching frequency are reached.

[0061] Specifically, this step belongs to the frequency smooth switching strategy. When the user changes the desired switching frequency online, the system needs to switch from the current frequency to the new frequency. To avoid voltage and current surges caused by frequency abrupt changes, this invention employs a smooth transition mechanism. Step S304 above includes: Step S3041: If the integer carrier ratio remains unchanged, keep the integer carrier ratio unchanged, and adjust the modulation wave frequency from the current value to the new value at a preset gradual rate, and the carrier frequency corresponds to the target switching frequency.

[0062] Specifically, let the current operating frequency be... The new target switching frequency is The system first calculates the integer carrier ratio corresponding to the new target switching frequency according to steps S301 to S303. and modulation wave frequency .

[0063] If the new integer carrier ratio is equal to the previous integer carrier ratio, that is... Only the modulation wave frequency needs to be adjusted. from Gradually transition to the new frequency at a preset transition rate (e.g., 1 Hz / s). Meanwhile, carrier frequency Synchronous changes.

[0064] Step S3042: If the integer carrier ratio changes, first keep the current modulation wave frequency unchanged, adjust the carrier frequency to the carrier frequency corresponding to the changed integer carrier ratio at a preset gradual rate, and then adjust the modulation wave frequency to the new value at a preset gradual rate.

[0065] Specifically, if In this case, both the carrier ratio and the modulation frequency need to be adjusted simultaneously. The system will first maintain the current modulation frequency. Keep it unchanged, change the carrier frequency from Gradually change to a constant rate (e.g., 10 Hz / ms) (During this process, the carrier ratio becomes a non-integer, but the transition time is extremely short, and the subharmonic effect is negligible.) Then, the modulation wave frequency is adjusted from... Gradient to Throughout the process, the carrier phase remains continuous, avoiding impact.

[0066] It should be noted that during frequency switching, the adaptive voltage equalization parameters are updated in real time with the instantaneous carrier frequency.

[0067] Step S305: Collect the current in the power cycle test circuit; when the absolute value of the current is greater than or equal to a preset threshold, determine the sign of the duty cycle correction based on the current direction, and calculate the duty cycle correction based on the sign; when the absolute value of the current is less than the preset threshold, keep the current direction sign unchanged before entering the interval less than the preset threshold, and calculate the duty cycle correction based on the kept current direction sign; correct the sinusoidal modulation wave or comparison result based on the duty cycle correction.

[0068] Specifically, this step belongs to the process of zero-crossing duty cycle correction smoothing strategy. The core of this strategy is to smooth the current direction signal used to calculate the duty cycle correction near the current zero-crossing point to avoid positive and negative jumps in the correction amount, thereby eliminating modulation wave jitter.

[0069] The specific implementation is as follows: 1) The bridge arm current in the power cycling test circuit is acquired in real time, and high-frequency noise is removed by low-pass filtering to obtain the current. .

[0070] 2) Set the threshold for the zero-crossing smoothing interval. (That is, a preset threshold, preferably 2% to 5% of the rated current). When When the current direction is reliable, the sign of the current direction is directly adopted. (Current direction symbol, +1 or -1) is used for correction calculation.

[0071] 3) When At this point, the system enters the zero-crossing smoothing region, where the current direction is unreliable. Within this region, the sign of the current direction is no longer determined by the instantaneous current, but rather by one of the following smoothing methods: Holding method: Current direction Maintain the direction value as before entering the smoothing interval until the absolute value of the current exceeds... And confirm that the zero crossing is complete; Gradual change method: When a change in the actual current direction is detected, the current direction... The current value is gradually changed to a new direction value in a linear or first-order inertial manner, with the change time ranging from 2 to 5 switching cycles.

[0072] Step S306: Based on the ratio of the current carrier frequency to the preset reference carrier frequency, adjust the proportional coefficient and integral coefficient of the voltage equalization control proportionally. The adjusted proportional coefficient and integral coefficient are used to calculate the duty cycle correction. Based on the ratio, adjust the maximum allowable duty cycle adjustment limit value within each switching cycle proportionally. The adjusted maximum duty cycle adjustment limit value is used to constrain the range of the duty cycle correction value.

[0073] This step pertains to a wide-frequency-range adaptive voltage equalization strategy. The core of this strategy is establishing an adaptive mapping relationship between the switching frequency and the voltage equalization controller parameters to ensure consistent voltage equalization performance across the entire frequency range. Specifically, this includes: 1) Adaptive scaling factor: Set the reference switching frequency (e.g., 200Hz, which is in the middle of the commonly used switching frequency range), reference scaling factor For the actual operating switching frequency The formula for calculating the adaptive scaling factor is as follows: (1); in, This is an adaptive scaling factor.

[0074] 2) Adaptive integral coefficients: The ratio of the integral coefficient to the proportional coefficient is kept constant to ensure that the control loop damping ratio does not change with frequency. Similar to the proportional coefficient, the adaptive integral coefficient is: (2); in, For adaptive integral coefficients, The base integral coefficient.

[0075] 3) Adaptive range limiting of duty cycle correction: The limiting range determines the maximum allowable duty cycle adjustment within each switching cycle (expressed as a per-unit value of the modulation amplitude). Limiting primarily affects the maximum charge transfer per cycle and is directly proportional to the switching cycle. At low frequencies, the switching cycle is longer, allowing for larger single adjustments (longer charging / discharging times), and the limiting range is proportionally amplified. At high frequencies, the switching cycle is short. If the adjustment amount is too large in a single operation, it can easily cause over-adjustment. Therefore, the limiting range is reduced proportionally.

[0076] (3); in, The adaptive limiting range for the current carrier frequency. This is the baseline limiting range.

[0077] 4) Differentiated configuration of auxiliary valves and test sample valves: The reference parameters for the auxiliary valve and the test valve are set separately, both using the same adaptive function form but different reference values. The auxiliary valve has a narrow limiting range, while the test valve has a wide limiting range.

[0078] Step S307: Compare the sinusoidal modulated wave with the triangular carrier wave, generate a switching drive signal based on the comparison result, and drive the IGBT sub-module in the power cycle test circuit based on the switching drive signal.

[0079] Specifically, after receiving the modulation wave frequency and integer carrier ratio, the valve base controller first generates a sinusoidal modulation wave according to the modulation wave frequency, and calculates the duty cycle correction amount based on the current direction sign after the current zero-crossing smoothing process in the power cycle test circuit and the adaptive voltage equalization parameters. The duty cycle correction amount is then superimposed on the sinusoidal modulation wave to obtain the corrected modulation wave. At the same time, a triangular carrier wave is generated according to the target switching frequency, and carrier waves with an initial phase difference of 120° are allocated to each IGBT sub-module in the auxiliary valve and the test valve according to the CPS-SPWM strategy. Then, the corrected modulation wave of each sub-module and its corresponding triangular carrier wave are sent to the comparator for real-time comparison. When the instantaneous value of the sinusoidal wave is higher than that of the triangular wave, a high level is output; when it is lower than that of the triangular wave, a low level is output, generating the original PWM pulse sequence corresponding to each sub-module. This pulse sequence is allocated by the valve base controller as upper and lower tube trigger signals and sent to the drive circuit of each sub-module through optical fiber or cable. After isolation and amplification by the drive circuit, the on and off of each IGBT sub-module is controlled.

[0080] The switching frequency control method provided in this embodiment, while maintaining an integer carrier ratio (without subharmonics), dynamically adjusts the modulation wave frequency to enable the switching frequency to cover all integer frequencies within the range of 50Hz to 1000Hz, achieving true continuous integer adjustability; it achieves a smooth transition between the carrier frequency and the modulation wave frequency during frequency switching to avoid voltage and current surges; it combines a zero-crossing duty cycle smoothing strategy to eliminate modulation wave jitter near the current zero-crossing point; and it establishes a real-time adaptive mapping between the switching frequency and the voltage equalization parameters to ensure consistent voltage equalization performance across the entire frequency range.

[0081] As one or more specific application embodiments of the present invention, the switching frequency control provided by the present invention will be further described in detail, and the specific process is as follows: S1: Receive the set target switching frequency (Integer, 50 to 1000 Hz); S2: Within the preset modulated wave frequency allowable range [ , Within [the specified range], find the integer carrier ratio. and modulation wave frequency Make ; S3: Using the modulation wave frequency Generate a sinusoidal modulated wave at the carrier frequency A triangular carrier wave is generated, and a CPS-SPWM trigger signal is generated using synchronous modulation. S4: Real-time acquisition of bridge arm current in power cycling test loop, smoothing current direction sign in the zero-crossing interval, and generating duty cycle correction amount; S5: Based on the current actual carrier frequency Real-time updates of adaptive pressure equalization control parameters; S6: When When changes occur, the carrier frequency and modulation wave frequency are adjusted at a gradual rate to smoothly switch to the new frequency.

[0082] like Figure 4 As shown, the main circuit control strategy of the "three-to-three" IGBT power cycling test loop is taken as an example: Modulation wave frequency carrier frequency The initial phases of the carrier waves in the three IGBT sub-modules within the test valve and auxiliary valve differ by 120° sequentially, generating CPS-SPWM trigger signals.

[0083] Set the desired switching frequency as Reference switching frequency Baseline integral coefficient Test sample valve reference proportional coefficient Test valve reference limit range Auxiliary valve reference proportional coefficient Auxiliary valve reference limit range Zero-crossing smoothing threshold Maintain the method to eliminate jitter.

[0084] Synchronous modulation is used, and an integer carrier ratio is taken. Then it is necessary It can accurately achieve 210Hz. Adaptive integral coefficient. The adaptive proportional coefficient of the test sample valve The adaptive correction range of the test sample valve Auxiliary valve adaptive proportional coefficient Auxiliary valve adaptive correction range When the target switching frequency is switched to other values, the system executes a smooth frequency switching strategy for a smooth transition.

[0085] A schematic diagram of carrier phase shift control for a single IGBT submodule is shown below. Figure 5 The diagram illustrates the signal flow and implementation logic of the switching frequency control method in this embodiment on an IGBT submodule. Setting: Reference Voltage Submodule voltage Current direction symbol Adaptive scaling factor Adaptive integral coefficients Modulation wave frequency carrier frequency Adaptive limiting range at the current carrier frequency , The duty cycle correction amount generated for the voltage control of the IGBT submodule (where, (The numbers are 1, 2, 3, 4, 5, 6, with an initial value of 0). To modulate the amplitude value, For the initial phase of the modulated wave, For carrier initial phase, For IGBT submodule upper tube trigger signal, For IGBT submodule The trigger signal for the lower tube.

[0086] (I) Pressure equalization control and adaptive parameter stage: Reference voltage With submodule voltage The difference is calculated to obtain the voltage deviation signal, which is then fed into the adaptive proportional coefficient. and adaptive integral coefficients Perform proportional-integral calculations. Among these, the adaptive proportional coefficient... and adaptive integral coefficients Adjust in real time according to the current carrier frequency.

[0087] (II) Current direction detection and zero-crossing smoothing process: The current in the acquisition loop is processed by current direction detection and zero-crossing smoothing to obtain the current direction sign. The sign of the duty cycle correction is determined by combining the current direction.

[0088] (III) Duty Cycle Correction Generation and Limiting Process: The duty cycle correction is generated by combining the proportional-integral calculation result with the current direction sign. And by the limited range The duty cycle correction is limited and output accordingly, also based on the current carrier frequency. Adaptive adjustment.

[0089] (iv) Sine modulated wave generation stage: Modulation amplitude Multiply by the sine function and add the duty cycle correction. Then, output submodule The corrected sinusoidal modulated wave.

[0090] (v) Carrier phase shifting and PWM comparison stage: submodule carrier initial phase (The three sub-modules within the test valve or auxiliary valve are sequentially spaced 120° apart) and the carrier frequency. A triangular carrier wave is generated together. The corrected sinusoidal modulated wave and the triangular carrier wave are fed into a comparator for comparison to generate the original PWM pulse sequence.

[0091] (vi) Trigger signal allocation and output stage: The original PWM pulses are logically distributed and output to the respective sub-modules. Upper tube trigger signal and lower tube trigger signal It is used to drive the upper and lower switching transistors in the IGBT submodule.

[0092] The switching frequency control method of this invention has the following beneficial effects: 1. Achieve continuous integer frequency setting without harmonics: By synchronously modulating the frequency of the variable modulation wave, the switching frequency can be precisely set to any integer within the range of 50~1000Hz while maintaining the integer carrier ratio, thus solving the limitation of traditional synchronous modulation that can only be taken as an integer multiple of the power frequency.

[0093] 2. Shockless frequency switching: A gradual transition mechanism between carrier frequency and modulation frequency is introduced to avoid voltage and current surges caused by direct jumps, supporting online dynamic frequency adjustment.

[0094] 3. Eliminate zero-crossing jitter: The zero-crossing duty cycle smoothing strategy makes the voltage balance of sub-modules more stable.

[0095] 4. Consistent voltage equalization performance across the entire frequency range: Adaptive parameter tuning ensures that the voltage equalization effect is comparable across different frequencies.

[0096] This embodiment also provides a switching frequency control device for implementing the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, hardware implementations, or a combination of software and hardware, are also possible and contemplated.

[0097] This embodiment provides a switching frequency control device, applied to a power cycling test circuit, such as... Figure 6 As shown, it includes: Parameter configuration module 601 is used to obtain the target switching frequency; The frequency calculation module 602 is used to determine the integer carrier ratio and the modulation wave frequency based on the preset allowable range of the modulation wave frequency, so that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range. The signal generation module 603 is used to generate a sinusoidal modulated wave based on the modulation wave frequency and a triangular carrier based on the target switching frequency, and the ratio of the frequency of the triangular carrier to the frequency of the sinusoidal modulated wave is kept as an integer carrier ratio; the sinusoidal modulated wave and the triangular carrier are compared, a switching drive signal is generated based on the comparison result, and the IGBT sub-module in the power cycle test circuit is driven based on the switching drive signal.

[0098] In some alternative implementations, the frequency calculation module 602 includes: The feasible carrier ratio enumeration unit is used to traverse the integer carrier ratio values ​​and calculate the modulation wave frequency corresponding to each value. The allowable range filtering unit is used to filter integer carrier ratios that keep the modulation wave frequency within the allowable range. The optimal carrier ratio selection unit is used to select the integer carrier ratio that minimizes the absolute value of the difference between the modulation wave frequency and the preset power frequency, if multiple integer carrier ratios are selected.

[0099] In some alternative embodiments, the device further includes: The frequency smoothing switching module is used to adjust the frequency of the triangular carrier and the frequency of the sinusoidal modulation wave at a preset gradual rate when the target switching frequency changes, until the carrier frequency and modulation wave frequency corresponding to the changed target switching frequency are reached.

[0100] In some alternative implementations, the frequency smoothing switching module includes: The first frequency switching unit is used to adjust the modulation wave frequency from the current value to a new value at a preset gradual rate if the integer carrier ratio remains unchanged, and the carrier frequency corresponds to the target switching frequency. The second frequency switching unit is used to, if the integer carrier ratio changes, first keep the current modulation wave frequency unchanged, adjust the carrier frequency at a preset gradual rate to the carrier frequency corresponding to the changed integer carrier ratio, and then adjust the modulation wave frequency at a preset gradual rate to the new value.

[0101] In one alternative embodiment, the device further includes: The zero-crossing duty cycle correction and smoothing module is used to collect the current in the power cycle test loop. When the absolute value of the current is greater than or equal to a preset threshold, the sign of the duty cycle correction is determined based on the current direction, and the duty cycle correction is calculated based on the sign. When the absolute value of the current is less than the preset threshold, the sign of the current direction before entering the interval less than or equal to the preset threshold remains unchanged, and the duty cycle correction is calculated based on the maintained current direction sign. The sinusoidal modulation wave or comparison result is corrected based on the duty cycle correction.

[0102] In one alternative embodiment, the device further includes: The wide-frequency-range adaptive voltage equalization module adjusts the proportional and integral coefficients of the voltage equalization control proportionally based on the ratio of the current carrier frequency to the preset reference carrier frequency. These adjusted coefficients are then used to calculate the duty cycle correction. Based on this ratio, the maximum allowable duty cycle adjustment limit is adjusted proportionally within each switching cycle. This adjusted maximum duty cycle adjustment limit constrains the range of the duty cycle correction value.

[0103] The switching frequency control device provided in this embodiment of the invention can execute the switching frequency control method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects for executing the method. Further functional descriptions of the various modules and units described above are the same as in the corresponding embodiments described above, and will not be repeated here.

[0104] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention.

[0105] The following is a detailed reference. Figure 7 The diagram illustrates a structural schematic suitable for implementing an electronic device according to embodiments of the present invention. The electronic device may include a processor (e.g., a central processing unit, graphics processor, etc.) 701, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 702 or a program loaded from memory 708 into random access memory (RAM) 703. The RAM 703 also stores various programs and data required for the operation of the electronic device. The processor 701, ROM 702, and RAM 703 are interconnected via a bus 704. An input / output (I / O) interface 705 is also connected to the bus 704.

[0106] Typically, the following devices can be connected to I / O interface 705: input devices 706 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 707 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; memory devices 708 including, for example, magnetic tapes, hard disks, etc.; and communication devices 709. Communication device 709 allows electronic devices to exchange data via wireless or wired communication with other devices. Although Figure 7 Electronic devices with various devices are shown, but it should be understood that it is not required to implement or have all of the devices shown, and more or fewer devices may be implemented or have instead.

[0107] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via a communication device 709, or installed from a memory 708, or installed from a ROM 702. When the computer program is executed by the processor 701, it performs the functions defined in the switching frequency control method of the embodiments of the present invention.

[0108] Figure 7 The electronic device shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments of the present invention.

[0109] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code. When the software or computer code is accessed and executed by the computer, processor, or hardware, the switching frequency control method shown in the above embodiments is implemented.

[0110] A portion of this invention can be applied as a computer program product, such as computer program instructions, which, when executed by a computer, can invoke or provide the methods and / or technical solutions according to the invention through the operation of the computer. Those skilled in the art will understand that the forms in which computer program instructions exist in a computer-readable medium include, but are not limited to, source files, executable files, installation package files, etc. Correspondingly, the ways in which computer program instructions are executed by a computer include, but are not limited to: the computer directly executing the instructions, or the computer compiling the instructions and then executing the corresponding compiled program, or the computer reading and executing the instructions, or the computer reading and installing the instructions and then executing the corresponding installed program. Here, the computer-readable medium can be any available computer-readable storage medium or communication medium accessible to a computer.

[0111] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A switching frequency control method, characterized in that, The method, applied to a power cycling test circuit, includes: Obtain the target switching frequency; Based on the preset allowable range of modulation wave frequency, an integer carrier ratio and a modulation wave frequency are determined such that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range. A sinusoidal modulated wave is generated based on the modulated wave frequency, and a triangular carrier wave is generated based on the target switching frequency, wherein the ratio of the frequency of the triangular carrier wave to the frequency of the sinusoidal modulated wave is maintained as the integer carrier ratio. The sinusoidal modulated wave is compared with the triangular carrier wave, a switching drive signal is generated based on the comparison result, and the IGBT sub-module in the power cycle test circuit is driven based on the switching drive signal.

2. The method according to claim 1, characterized in that, Determining the integer carrier ratio and modulation frequency based on a preset allowable range of modulation frequency includes: Iterate through the integer carrier ratio values ​​and calculate the modulation wave frequency corresponding to each value; Filter the integer carrier ratios that keep the modulation wave frequency within the allowable range; If multiple integer carrier ratios are selected, the integer carrier ratio that minimizes the absolute value of the difference between the modulation wave frequency and the preset power frequency is chosen.

3. The method according to claim 1, characterized in that, The method further includes: When the target switching frequency changes, the frequency of the triangular carrier and the frequency of the sinusoidal modulation wave are adjusted at a preset gradual rate until the carrier frequency and modulation wave frequency corresponding to the changed target switching frequency are reached.

4. The method according to claim 3, characterized in that, The step of adjusting the frequency of the triangular carrier wave and the frequency of the sinusoidal modulation wave at a preset gradual rate includes: If the integer carrier ratio remains unchanged, the integer carrier ratio is kept unchanged, and the modulation wave frequency is adjusted from the current value to the new value at a preset gradual rate, and the carrier frequency corresponds to the target switching frequency; If the integer carrier ratio changes, first keep the current modulation wave frequency unchanged, adjust the carrier frequency at a preset gradual rate to the carrier frequency corresponding to the changed integer carrier ratio, and then adjust the modulation wave frequency at a preset gradual rate to the new value.

5. The method according to claim 1, characterized in that, Before comparing the sinusoidal modulated wave with the triangular carrier wave, the method further includes: The current in the power cycle test circuit is collected; When the absolute value of the current is greater than or equal to a preset threshold, the sign of the duty cycle correction is determined based on the current direction, and the duty cycle correction is calculated based on the sign. When the absolute value of the current is less than the preset threshold, the current direction sign before entering the interval less than the preset threshold remains unchanged, and the duty cycle correction amount is calculated based on the maintained current direction sign. The sinusoidal modulation wave or comparison result is corrected based on the duty cycle correction amount.

6. The method according to claim 5, characterized in that, The method further includes: Based on the ratio of the current carrier frequency to the preset reference carrier frequency, the proportional coefficient and integral coefficient of the equalization control are adjusted proportionally, and the adjusted proportional coefficient and integral coefficient are used to calculate the duty cycle correction.

7. The method according to claim 6, characterized in that, The method further includes: Based on the ratio, the maximum allowable duty cycle adjustment limit value within each switching cycle is adjusted proportionally, and the adjusted maximum duty cycle adjustment limit value is used to constrain the range of the duty cycle correction amount.

8. A switching frequency control system, characterized in that, The system, applied to a power cycle test circuit, includes: a host computer, a control and protection subsystem, a valve base controller, and a sub-module drive circuit, wherein: The host computer is used to send the target switching frequency to the control and protection subsystem; The control and protection subsystem is used to acquire the target switching frequency; based on the allowable range of the preset modulation wave frequency, determine the integer carrier ratio and the modulation wave frequency, such that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range, and send the integer carrier ratio and the modulation wave frequency to the valve base controller; The valve base controller is used to generate a sinusoidal modulation wave based on the modulation wave frequency and a triangular carrier based on the target switching frequency, wherein the ratio of the frequency of the triangular carrier to the frequency of the sinusoidal modulation wave is maintained as the integer carrier ratio; the sinusoidal modulation wave is compared with the triangular carrier, a switching drive signal is generated based on the comparison result, and the switching drive signal is sent to the submodule drive circuit; The submodule drive circuit is used to drive the IGBT submodule in the power cycle test circuit based on the switch drive signal.

9. A switching frequency control device, characterized in that, The device, applied to a power cycling test circuit, comprises: The parameter configuration module is used to obtain the target switching frequency; The frequency calculation module is used to determine the integer carrier ratio and the modulation wave frequency based on the preset allowable range of the modulation wave frequency, such that the product of the integer carrier ratio and the modulation wave frequency is equal to the target switching frequency, and the modulation wave frequency is within the allowable range. The signal generation module is used to generate a sinusoidal modulation wave based on the modulation wave frequency and a triangular carrier based on the target switching frequency, wherein the ratio of the frequency of the triangular carrier to the frequency of the sinusoidal modulation wave is maintained as the integer carrier ratio; the sinusoidal modulation wave is compared with the triangular carrier, a switching drive signal is generated based on the comparison result, and the IGBT sub-module in the power cycle test circuit is driven based on the switching drive signal.

10. The apparatus according to claim 9, characterized in that, The frequency calculation module includes: The feasible carrier ratio enumeration unit is used to traverse the integer carrier ratio values ​​and calculate the modulation wave frequency corresponding to each value. The allowable range filtering unit is used to filter integer carrier ratios that keep the modulation wave frequency within the allowable range. The optimal carrier ratio selection unit is used to select the integer carrier ratio that minimizes the absolute value of the difference between the modulation wave frequency and the preset power frequency, if multiple integer carrier ratios are selected.

11. The apparatus according to claim 9, characterized in that, The device also includes: The frequency smoothing switching module is used to adjust the frequency of the triangular carrier and the frequency of the sinusoidal modulation wave at a preset gradual rate when the target switching frequency changes, until the carrier frequency and modulation wave frequency corresponding to the changed target switching frequency are reached.

12. The apparatus according to claim 11, characterized in that, The frequency smoothing switching module includes: The first frequency switching unit is used to adjust the modulation wave frequency from the current value to a new value at a preset gradual rate if the integer carrier ratio remains unchanged, and the carrier frequency corresponds to the target switching frequency. The second frequency switching unit is used to, if the integer carrier ratio changes, first keep the current modulation wave frequency unchanged, adjust the carrier frequency at a preset gradual rate to the carrier frequency corresponding to the changed integer carrier ratio, and then adjust the modulation wave frequency at a preset gradual rate to the new value.

13. The apparatus according to claim 12, characterized in that, The device also includes: The zero-crossing duty cycle correction and smoothing module is used to collect the current in the power cycle test loop. When the absolute value of the current is greater than or equal to a preset threshold, the sign of the duty cycle correction is determined based on the current direction, and the duty cycle correction is calculated based on the sign. When the absolute value of the current is less than the preset threshold, the sign of the current direction before entering the interval less than or equal to the preset threshold remains unchanged, and the duty cycle correction is calculated based on the maintained current direction sign. The sinusoidal modulation wave or comparison result is corrected based on the duty cycle correction.

14. The apparatus according to claim 13, characterized in that, The device also includes: The wide-frequency-range adaptive voltage equalization module adjusts the proportional and integral coefficients of the voltage equalization control proportionally based on the ratio of the current carrier frequency to the preset reference carrier frequency. These adjusted coefficients are then used to calculate the duty cycle correction. Based on this ratio, the maximum allowable duty cycle adjustment limit is adjusted proportionally within each switching cycle. This adjusted maximum duty cycle adjustment limit constrains the range of the duty cycle correction value.

15. An electronic device, characterized in that, include: A memory and a processor are communicatively connected, the memory stores computer instructions, and the processor executes the switching frequency control method of any one of claims 1 to 7 by executing the computer instructions.

16. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the switching frequency control method according to any one of claims 1 to 7.

17. A computer program product, characterized in that, Includes computer instructions for causing a computer to perform the switching frequency control method according to any one of claims 1 to 7.

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