Voltage stabilization method and system based on frequency converter direct current bus

Abstract

The invention discloses a voltage stabilization method and system based on a frequency converter direct current bus, and the method comprises the steps: employing a super capacitor and a direct current bus to be connected in parallel to construct a virtual capacitor, collecting data, carrying out the preprocessing of the data, and outputting a standardized data set; based on the standardized data set, a virtual capacitance value is obtained and used for controlling the super capacitor to correct parameters, and meanwhile the SOC of the virtual capacitor is obtained; obtaining a dynamic bus voltage reference according to the working condition data, obtaining a corrected actual voltage deviation by combining the DC bus voltage, obtaining a correction error by comparing the corrected actual voltage deviation with a target deviation, and obtaining a correction parameter weight by combining the IGBT chip junction temperature; and judging the state of the direct-current bus according to the dynamic bus voltage reference, and controlling the virtual capacitor to charge and discharge based on the working condition data and the SOC of the virtual capacitor so as to stabilize the voltage of the direct-current bus. Through the mode, the direct current bus can be accurately adjusted, so that the voltage of the direct current bus is ensured to be in a stable state, and the performance and the service life of the frequency converter are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of frequency converters, in particular to a voltage stabilization method and system based on a DC bus of a frequency converter. BACKGROUND

[0002] The core function of a frequency converter is to control the motor speed by changing the power supply frequency of the motor, usually by controlling the power supply frequency to achieve precise control of the motor speed. The DC bus in the frequency converter rectifies alternating current to direct current to stabilize the voltage, which can achieve smooth fluctuation of the power supply and reduce the impact on the output of the frequency converter. It also has the advantages of compact structure, reduced electromagnetic interference, and strong adaptability.

[0003] Currently, the control of the DC bus of the frequency converter usually adopts compensation strategy or ripple suppression method, but this method cannot cope with complex working conditions and composite disturbances, and lacks coordination for power grid fluctuations, resulting in defects in adaptability and stability, which affects the service life of components. SUMMARY

[0004] Therefore, the present application mainly proposes a voltage stabilization method and system based on a DC bus of a frequency converter to solve the problem of inaccurate and precise control of the DC bus voltage of the frequency converter and improve the service life and stability of the frequency converter.

[0005] To solve the above technical problems, one technical solution adopted by the present application is to provide a voltage stabilization method based on a DC bus of a frequency converter, comprising the steps of: S10: A virtual capacitor is constructed by connecting a super capacitor in parallel with a DC bus, DC bus voltage data, load current, energy flow direction, IGBT chip junction temperature and working condition data are collected, the data is preprocessed and a standardized data set is outputted; S20: Based on the standardized data set, the virtual capacitor value is obtained and used to control the super capacitor to correct the parameters, and the virtual capacitor SOC is also obtained; S30: The dynamic bus voltage reference is obtained according to the working condition data, the corrected actual voltage deviation is obtained in combination with the DC bus voltage, the correction error is obtained by comparing with the target deviation, and the correction parameter weight is obtained in combination with the IGBT chip junction temperature; S40: The DC bus state is judged according to the dynamic bus voltage reference, and the virtual capacitor SOC is controlled based on the working condition data and the virtual capacitor SOC to stabilize the voltage of the DC bus.

[0006] In one possible implementation, the step of preprocessing the data and outputting the standardized data set comprises: S11: sequentially filtering and normalizing the DC bus voltage data, the load current, the energy flow, the IGBT chip junction temperature, and the working condition data according to different types.

[0007] In a possible implementation, the step of obtaining a virtual capacitance value based on the standardized data set and using the virtual capacitance value to control the super capacitor to correct a parameter, and simultaneously obtaining a virtual capacitance SOC, comprises: S21: obtaining a virtual capacitance value by using weighted dynamic mapping output according to the DC bus voltage data and the IGBT chip junction temperature.

[0008] In a possible implementation, the step of obtaining a virtual capacitance value based on the standardized data set and using the virtual capacitance value to control the super capacitor to correct a parameter, and simultaneously obtaining a virtual capacitance SOC, further comprises: S22: obtaining an ideal compensation current according to the virtual capacitance value, and adjusting the duty cycle of the bidirectional DC converter to control the charge and discharge current of the super capacitor.

[0009] In a possible implementation, the step of obtaining a dynamic bus voltage reference according to the working condition data, obtaining a corrected actual voltage deviation by combining the DC bus voltage, comparing the corrected actual voltage deviation with a target deviation to obtain a correction error, and obtaining a correction parameter weight by combining the IGBT chip junction temperature, comprises: S31: adjusting a ripple suppression coefficient according to the virtual capacitance value and the DC bus voltage data, and when the virtual capacitance value has reached an upper limit, adjusting the ripple suppression coefficient at a higher coefficient according to the DC bus voltage data, the ripple suppression coefficient being used to control the charge and discharge response speed of the bidirectional DC converter.

[0010] In a possible implementation, the step of obtaining a dynamic bus voltage reference according to the working condition data, obtaining a corrected actual voltage deviation by combining the DC bus voltage, comparing the corrected actual voltage deviation with a target deviation to obtain a correction error, and obtaining a correction parameter weight by combining the IGBT chip junction temperature, comprises: S32: the greater the correction error, the greater the correction parameter weight, and the greater the correction strength; in a possible implementation, the step of obtaining a dynamic bus voltage reference according to the working condition data, comprises: S33: determining a reference value of the DC bus according to the DC bus voltage data and the working condition data, and correcting the reference value according to the IGBT chip junction temperature and the virtual capacitance SOC.

[0011] In one possible implementation, the step of determining the DC bus state based on the dynamic bus voltage reference and controlling the charging and discharging of the virtual capacitor to stabilize the DC bus voltage based on the operating condition data and the virtual capacitor SOC includes: S41: When regenerative energy is generated and the virtual capacitor SOC is lower than the first threshold, the regenerative energy is stored in the supercapacitor; when the virtual capacitor SOC exceeds the second threshold, the regenerative energy is switched and supplied to the auxiliary load; the first threshold is less than the second threshold.

[0012] In one possible implementation, after the steps of determining the DC bus state based on the dynamic bus voltage reference and controlling the charging and discharging of the virtual capacitor to stabilize the DC bus voltage based on the operating condition data and the virtual capacitor SOC, the method further includes: S50: Monitor the control effect, collect the voltage deviation, ripple coefficient, virtual capacitance SOC, and IGBT chip junction temperature of the DC bus after correction, and compare them with the control target. If the target is met, maintain the weight of the correction parameters; if the target is not met, repeat step S30 to adjust the weight of the correction parameters.

[0013] To solve the above-mentioned technical problems, another technical solution adopted in this application is: to provide a voltage stabilization system based on the DC bus of a frequency converter, applicable to the voltage stabilization method based on the DC bus of a frequency converter as described above, including: The data acquisition module is used to construct a virtual capacitor by connecting a supercapacitor in parallel with the DC bus, and to acquire DC bus voltage data, load current, energy flow direction, IGBT chip junction temperature and operating condition data. The data is preprocessed and outputs a standardized dataset. The calculation module is used to obtain virtual capacitance values ​​based on the standardized dataset, and to control the supercapacitor to correct parameters, while also obtaining the virtual capacitance SOC; The optimization module is used to obtain a dynamic bus voltage reference based on the operating condition data, obtain the corrected actual voltage deviation by combining it with the DC bus voltage, compare it with the target deviation to obtain the correction error, and then obtain the correction parameter weights by combining it with the IGBT chip junction temperature. The correction module is used to determine the DC bus status based on the dynamic bus voltage reference, and control the charging and discharging of the virtual capacitor based on the operating condition data and the virtual capacitor SOC to stabilize the DC bus voltage.

[0014] The beneficial effects of this application are as follows: Unlike the prior art, this application discloses a voltage stabilization method and system based on the DC bus of a frequency converter. By collecting and simulating data and then performing correction and feedback verification, the DC bus can be precisely adjusted, thereby ensuring that the voltage of the DC bus is in a stable state, thus improving the performance and service life of the frequency converter. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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, wherein: Figure 1 This is a flowchart of a voltage stabilization method based on the DC bus of a frequency converter in one embodiment of this application. Detailed Implementation

[0016] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0017] The terms "first," "second," and "third" used in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. 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 device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0018] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0019] Please see Figure 1 This application proposes a voltage stabilization method based on the DC bus of a frequency converter, including the following steps: S10: A virtual capacitor is constructed by connecting a supercapacitor in parallel with the DC bus. DC bus voltage data, load current, energy flow direction, IGBT chip junction temperature and operating condition data are collected, and the data is preprocessed and output as a standardized dataset. S20: Based on a standardized dataset, obtain virtual capacitance values ​​and use them to control the supercapacitor to correct parameters, while also obtaining the virtual capacitance SOC; S30: Obtain the dynamic bus voltage reference based on the operating condition data, combine it with the DC bus voltage to obtain the corrected actual voltage deviation, compare it with the target deviation to obtain the correction error, and then combine it with the IGBT chip junction temperature to obtain the correction parameter weights. S40: Determines the DC bus status based on the dynamic bus voltage reference, and controls the charging and discharging of the virtual capacitor to stabilize the DC bus voltage based on the operating condition data and the virtual capacitor SOC.

[0020] Specifically, in step S10, a small-capacity supercapacitor is connected in parallel with the DC bus, and combined with subsequent algorithms, the energy storage characteristics of a large-capacity physical capacitor are simulated to solve the problem of performance degradation caused by the aging of the physical capacitor.

[0021] The DC bus voltage data includes the voltage between the two poles of the DC bus and the ground terminal of the IGBT heatsink, the voltage drop across the equivalent series resistance (ESR) of the filter capacitor at the DC input of the inverter bridge (the latter is used to obtain the physical capacitor aging rate), the current energy flow direction is determined by a bidirectional current sensor, the junction temperature of the IGBT chip is collected by the thermistor built into the IGBT, and the load type (such as fan, machine tool) is determined by the current ripple frequency and voltage fluctuation. After processing the above data, a standardized dataset is output. The standardized dataset is divided according to the acquisition time, and each standardized dataset includes at least the DC bus voltage V. d Load current I, IGBT chip junction temperature T, and physical capacitor aging rate R.

[0022] In step S20, the real-time virtual capacitance value C is obtained based on the data from the standardized dataset. v Specifically, the formula can be used: , Where C b The reference virtual capacitance value is k1, k2, and k3, which are the voltage fluctuation coefficient, temperature coefficient, and aging compensation coefficient, respectively, used to adjust the weight of the corresponding parameters. In this embodiment, they are initially set to 0.8, 0.5, and 0.6, respectively. The coefficients can be obtained and adjusted based on actual testing and experience.

[0023] The virtual capacitance value is an equivalent capacitance simulated by the algorithm, rather than the actual capacitance of the physical capacitor. It is used to compensate for the deficiencies of the physical capacitor. When data fluctuations are detected, the virtual capacitance changes accordingly to maintain the DC bus's ability to suppress ripple. The virtual capacitance value is used to send duty cycle commands to the bidirectional DC / DC converter to control the charging and discharging of the supercapacitor, thereby achieving voltage regulation.

[0024] In step S30, the core is to continuously update the parameter weight W based on the correction error and the junction temperature of the IGBT chip. The update formula is: , Where α is the learning rate, used to control the weight update speed, e is the correction error, and V t For the target deviation, I c To compensate for the current, sgn is a sign function used to ensure that the weight adjustment direction is consistent with the voltage correction direction. It outputs 1, -1, or 0 based solely on the positive or negative value of the result. In this embodiment, when V... d with I c The correction error e comes from the difference between the corrected actual DC bus voltage and the dynamic bus voltage reference in step S20. The corrected actual DC bus voltage can be directly obtained after step S20 and before the start of the next acquisition cycle. The dynamic bus voltage reference V... f The specific value depends on the inverter's rated parameters and the load type, and can be obtained using the following formula: , Where V r The rated voltage of the DC bus, k t The load type weight is set to 1 in this embodiment, and P is the load type coefficient, which is determined based on the identified load type. In this embodiment, it is 0 for fans, 0.05 for machine tools, and 0.08 for heavy-duty equipment. This means that the more frequent the load fluctuations, the larger the coefficient, and thus more voltage margin is reserved. The dynamic bus voltage reference V is obtained. f Afterwards, by comparing it with the corrected actual DC bus voltage, the correction error e can be obtained, and then the correction parameter weight can be obtained. The correction parameter weight is used to adjust the strength and intensity of subsequent energy diversion.

[0025] In step S40, the current energy flow direction of the DC bus is determined based on the standardized dataset, and then a corresponding strategy is selected based on the virtual capacitor SOC status. If the virtual capacitor SOC is low, the bidirectional DC / DC converter is controlled to input energy into the supercapacitor to supplement the corresponding energy storage of the virtual capacitor value; if the virtual capacitor SOC is high, to avoid capacitor overvoltage damage, the path is switched to auxiliary load power supply to ensure DC bus voltage stability.

[0026] This technical solution combines the setting of virtual capacitors with real-time data feedback. Through data processing and simulation, it achieves precise adjustment of the DC bus, thereby ensuring that the DC bus voltage is in a stable state, thus improving the performance and service life of the frequency converter.

[0027] In one embodiment, the step of preprocessing the data and outputting a standardized dataset includes: S11: The DC bus voltage data, load current, energy flow, IGBT chip junction temperature and operating condition data are filtered and normalized in sequence according to different types.

[0028] Specifically, the data is first filtered to remove high-frequency noise, and then the denoised data is normalized. The data is converted into values ​​in the range [0,1] according to the preset range of each data. Since the noise sources of different data are different, the filtering and denoising steps will be different. For example, for the acquisition of DC bus voltage, noise with frequencies above 20kHz (caused by switching) can be removed. For the acquisition of load current, Kalman filtering can be used. For the junction temperature of IGBT chip, first-order low-pass filtering is used. Targeted adjustment methods can be adopted according to specific circumstances.

[0029] In one embodiment, the step of obtaining a virtual capacitance value based on a standardized dataset and using it to control the supercapacitor to correct parameters, while simultaneously obtaining the virtual capacitance SOC, includes: S21: Based on the DC bus voltage data and the IGBT chip junction temperature, a weighted dynamic mapping output is used to obtain the virtual capacitance value.

[0030] Formulas can be used , The virtual capacitance value C is obtained by weighting the factors. v .

[0031] In one embodiment, the step of obtaining a virtual capacitance value based on a standardized dataset and using it to control the supercapacitor to correct parameters, while simultaneously obtaining the virtual capacitance SOC, further includes: S22: Obtain the ideal compensation current based on the virtual capacitance value, and adjust the duty cycle by adjusting the bidirectional DC-DC converter to control the charging and discharging current of the supercapacitor.

[0032] Specifically, after obtaining the virtual capacitance value, the ideal compensation current I is obtained according to the capacitance current formula. i : , After acquiring the ideal compensation current, the bidirectional DC / DC converter adjusts the duty cycle in real time to control the supercapacitor's charging and discharging actions, thereby controlling the DC bus voltage. Furthermore, the ideal compensation current can be corrected and limited based on the load current to ensure the final current is within a reasonable range, thus guaranteeing both safety and sufficient power supply.

[0033] In one embodiment, the steps of obtaining a dynamic bus voltage reference based on operating condition data, obtaining the corrected actual voltage deviation by combining it with the DC bus voltage, comparing it with the target deviation to obtain the correction error, and then obtaining the correction parameter weights by combining it with the IGBT chip junction temperature include: S31: Adjust the ripple suppression coefficient according to the virtual capacitance value and DC bus voltage data. When the virtual capacitance value has reached the upper limit, adjust the ripple suppression coefficient with a higher coefficient according to the DC bus voltage data. The ripple suppression coefficient is used to control the charging and discharging response speed of the bidirectional DC converter.

[0034] Specifically, based on the virtual capacitance value C v The ripple suppression coefficient is adjusted based on the capacitor aging rate R in the DC bus voltage data. The initial ripple suppression coefficient can be set to 1.0. If the virtual capacitance value reaches or exceeds the design limit, it indicates that the hardware buffer capacity has been exhausted, and the ripple suppression coefficient is increased to 1.2. Simultaneously, the ripple suppression coefficient is adjusted according to the capacitor aging rate. For example, starting from 10% aging rate, the ripple suppression coefficient increases by 8% for every 10% increase. When the capacitor aging rate exceeds 30%, the ripple suppression coefficient increases by an additional 10% to offset the ripple amplification effect caused by physical capacitor attenuation. For example, the virtual capacitance value C... v The design limit has been reached, and the aging rate is 20%. At this time, the ripple suppression coefficient is 1.2*(1+8%*1), which is 1.296.

[0035] The ripple suppression coefficient can be used to control the response speed of the bidirectional DC / DC converter, thereby adjusting the supercapacitor's ability to absorb high-frequency ripple. Alternatively, it can be adjusted by changing the learning rate α in the parameter weights W to achieve algorithm-hardware co-correction. Specifically, increasing the ripple suppression coefficient shortens the response delay of the bidirectional DC / DC converter and increases the learning rate α; conversely, decreasing the ripple suppression coefficient increases the response delay of the bidirectional DC / DC converter and decreases the learning rate α. In one embodiment, the steps of obtaining a dynamic bus voltage reference based on operating condition data, obtaining the corrected actual voltage deviation by combining it with the DC bus voltage, comparing it with the target deviation to obtain the correction error, and then obtaining the correction parameter weights by combining it with the IGBT chip junction temperature include: S32: The larger the correction error, the greater the weight of the correction parameter and the stronger the correction; the smaller the correction error, the less the weight of the correction parameter and the weaker the correction.

[0036] Specifically, the formula is updated based on the parameter weights: , The correction error e is obtained by comparing the actual voltage deviation with the target deviation, and the parameter weights are updated based on this correction error. The parameter weights are then optimized by simulating the plasticity of neural synapses to achieve dynamic adjustment.

[0037] In one embodiment, the step of obtaining a dynamic bus voltage reference based on operating condition data includes: S33: Determine the reference value of the DC bus based on the DC bus voltage data and operating condition data. Then, correct the reference value based on the IGBT chip junction temperature and virtual capacitance SOC.

[0038] Specifically, the dynamic bus voltage reference V f The specific value depends on the inverter's rated parameters and the load type, and can be obtained using the following formula: , Obtain dynamic bus voltage V f Then, it can be further fine-tuned, as shown in the following formula: , Where V fa For the adjusted dynamic bus voltage, k t k is the temperature correction factor. c C is the capacitance state coefficient. soc This represents the virtual capacitance SOC. In this embodiment, the temperature correction factor k... t The weight used to adjust the junction temperature of the IGBT chip is initially set to 0.03. Higher IGBT chip junction temperatures, slower switching speeds, and longer dead times increase the likelihood of bus voltage deviations. In such cases, the temperature correction factor k should be appropriately increased. t Capacitor state coefficient k c The initial value is 0.02. However, the lower the virtual capacitor SOC, the weaker its ability to buffer voltage fluctuations. Therefore, it is necessary to appropriately increase the capacitor state factor to avoid undervoltage caused by sudden load increases.

[0039] By further adjusting the dynamic bus voltage to update the correction error e, stable control of the DC bus voltage is achieved through the adjustment of the parameter weight W.

[0040] In one embodiment, the step of determining the DC bus state based on a dynamic bus voltage reference and controlling the charging and discharging of the virtual capacitor to stabilize the DC bus voltage based on operating condition data and the virtual capacitor's state of charge (SOC) includes: S41: When regenerative energy is generated and the virtual capacitor SOC is lower than the first threshold, the regenerative energy is stored in the supercapacitor; when the virtual capacitor SOC exceeds the second threshold, the regenerative energy is switched and supplied to the auxiliary load; the first threshold is less than the second threshold.

[0041] Specifically, in this embodiment, the first threshold is 80%, and the second threshold is 90%. That is, when the energy flow direction is determined to be in regenerative mode in step S10, such as motor braking or deceleration, energy is fed back from the motor to the inverter's DC bus. If the virtual capacitor SOC is below 80%, the supercapacitor still has energy storage space, and the regenerative energy is introduced into the capacitor to quickly absorb the excess energy of the DC bus, thus playing a voltage stabilizing role. If the virtual capacitor SOC is above 90%, the supercapacitor is close to full charge, and the energy storage space is insufficient. Continuing to charge may cause overvoltage damage. In this case, the path is switched and the energy is supplied to the auxiliary load (such as heat sink, control power supply, etc.) to ensure the voltage stabilizing effect. Furthermore, before switching the path to supply energy to the auxiliary load, the ratio of the load current I to the rated current can be used to determine how to distribute energy among the loads.

[0042] In one embodiment, after determining the DC bus state based on a dynamic bus voltage reference and controlling the charging and discharging of the virtual capacitor to stabilize the DC bus voltage based on operating condition data and the virtual capacitor's state of charge (SOC), the method further includes: S50: Monitor the control effect, collect the voltage deviation, ripple coefficient, virtual capacitance SOC, and IGBT chip junction temperature after DC bus correction, and compare them with the control target. If the target is met, maintain the correction parameter weights; if the target is not met, re-execute step S30 to adjust the correction parameter weights.

[0043] Specifically, the target range of parameters can be set based on hardware specifications and voltage regulation requirements. The corrected parameters are then detected and compared with the target range. If they are within the target range, the correction is considered correct. If they are outside the target range, the parameter weight W, ripple suppression coefficient, and other parameters are adjusted, and the aforementioned steps are repeated to achieve voltage regulation of the DC bus.

[0044] In this embodiment, the target range of parameters is: DC bus voltage deviation is ±2%, DC bus voltage ripple coefficient is within 3%, virtual capacitor SOC is maintained at 10-90%, and IGBT chip junction temperature does not exceed 110℃ (88% of the maximum value).

[0045] This embodiment also includes a voltage stabilization system based on the inverter's DC bus, applicable to the aforementioned voltage stabilization method based on the inverter's DC bus, including: The data acquisition module is used to construct a virtual capacitor by connecting a supercapacitor in parallel with the DC bus, and to acquire DC bus voltage data, load current, energy flow direction, IGBT chip junction temperature and operating condition data. The data is preprocessed and outputs a standardized dataset. The calculation module is used to obtain virtual capacitance values ​​based on a standardized dataset and to control the supercapacitor to correct parameters, while also obtaining the virtual capacitance SOC. The optimization module is used to obtain a dynamic bus voltage reference based on operating condition data, combine it with the DC bus voltage to obtain the corrected actual voltage deviation, compare it with the target deviation to obtain the correction error, and then combine it with the IGBT chip junction temperature to obtain the correction parameter weights. The correction module is used to determine the DC bus status based on the dynamic bus voltage reference, and to control the charging and discharging of the virtual capacitor based on the operating condition data and the virtual capacitor SOC to stabilize the DC bus voltage.

[0046] In one embodiment of this application, the scheme includes setting up a charger, a supercapacitor, and a DC-DC converter as a voltage stabilization device. The charger has charging and current limiting protection functions, and also houses various semiconductor devices (such as IGBT chips). The supercapacitor is used to construct a virtual capacitor, which can serve as a supplementary energy device for storing loads. The DC-DC converter is used to adjust the duty cycle to control the charging and discharging of the supercapacitor.

[0047] In a specific solution, a voltage stabilization system based on the inverter's DC bus is equipped with four sets of voltage stabilization devices, with two sets forming a unit. The output of each device is connected to the DC bus of the customer's power grid. The customer's power grid is located at the end of a branch line, and some critical equipment experiences voltage dips or terminations due to instantaneous fluctuations in the grid voltage, leading to frequent inverter failures and shutdowns, severely impacting production operations. The minimum preset voltage of the DC bus is 460V. When it falls below 460V, calculations are performed based on various detection data and standardized datasets. A diode is forward-biased to respond to power output, and a supercapacitor is discharged through a DC-DC converter to raise the DC bus to the normal range (around 510V). At this point, the diode is reverse-biased to cut off, and the charger starts working, controlling the charging of the supercapacitor for future needs. This device can be installed independently, has a small footprint, is easy to install, has a fast response time, high reliability, a response time of no more than 200μs without disturbance, expandable output ports, and features built-in detection and port protection. It does not affect the existing power system and has the advantages of safety, reliability, and protection of personal safety. By adopting the voltage stabilization system based on the DC bus of the frequency converter in this embodiment, the customer's power grid ensures the stable operation of the frequency converter during voltage fluctuations, ensures full-load output, is safe and reliable, and improves the efficiency and stability of production operations.

[0048] Since the system implementation corresponds to the method implementation described above, the description of the voltage stabilization system based on the inverter DC bus of this application is the same as that of the method implementation described above, and will not be repeated here. Accordingly, it also has the same beneficial effects as the method described above.

[0049] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A voltage stabilization method based on the DC bus of a frequency converter, characterized in that, Including the following steps: S10: A virtual capacitor is constructed by connecting a supercapacitor in parallel with the DC bus. DC bus voltage data, load current, energy flow direction, IGBT chip junction temperature and operating condition data are collected, and the data is preprocessed and output as a standardized dataset. S20: Based on the standardized dataset, obtain the virtual capacitance value and use it to control the supercapacitor to correct parameters, and at the same time obtain the virtual capacitance SOC; S30: Obtain the dynamic bus voltage reference based on the operating condition data, obtain the corrected actual voltage deviation by combining it with the DC bus voltage, compare it with the target deviation to obtain the correction error, and then obtain the correction parameter weight by combining it with the IGBT chip junction temperature. S40: Determine the DC bus status based on the dynamic bus voltage reference, and control the charging and discharging of the virtual capacitor based on the operating condition data and the virtual capacitor SOC to stabilize the DC bus voltage.

2. The voltage stabilization method based on the DC bus of a frequency converter according to claim 1, characterized in that, The steps of preprocessing the data and outputting a standardized dataset include: S11: The DC bus voltage data, the load current, the energy flow direction, the IGBT chip junction temperature, and the operating condition data are filtered and normalized sequentially according to different types.

3. The voltage stabilization method based on the DC bus of a frequency converter according to claim 1, characterized in that, The step of obtaining virtual capacitance values ​​based on the standardized dataset and using them to control the supercapacitor to correct parameters, while simultaneously obtaining the virtual capacitance SOC, includes: S21: Based on the DC bus voltage data and the IGBT chip junction temperature, a weighted dynamic mapping output is used to obtain the virtual capacitance value.

4. The voltage stabilization method based on the DC bus of a frequency converter according to claim 3, characterized in that, The step of obtaining virtual capacitance values ​​based on the standardized dataset and using them to control the supercapacitor to correct parameters, while simultaneously obtaining the virtual capacitance SOC, further includes: S22: Obtain the ideal compensation current based on the virtual capacitance value, and adjust the duty cycle by adjusting the bidirectional DC-DC converter to control the charging and discharging current of the supercapacitor.

5. The voltage stabilization method based on the DC bus of a frequency converter according to claim 4, characterized in that, The steps of obtaining a dynamic bus voltage reference based on the operating condition data, obtaining the corrected actual voltage deviation by combining it with the DC bus voltage, comparing it with the target deviation to obtain the correction error, and then obtaining the correction parameter weights by combining it with the IGBT chip junction temperature include: S31: Adjust the ripple suppression coefficient according to the virtual capacitance value and the DC bus voltage data. When the virtual capacitance value has reached the upper limit, adjust the ripple suppression coefficient with a higher coefficient according to the DC bus voltage data. The ripple suppression coefficient is used to control the charging and discharging response speed of the bidirectional DC converter.

6. The voltage stabilization method based on the DC bus of a frequency converter according to claim 1, characterized in that, The steps of obtaining a dynamic bus voltage reference based on the operating condition data, obtaining the corrected actual voltage deviation by combining it with the DC bus voltage, comparing it with the target deviation to obtain the correction error, and then obtaining the correction parameter weights by combining it with the IGBT chip junction temperature include: S32: The larger the correction error, the greater the weight of the correction parameter, and the stronger the correction; the smaller the correction error, the smaller the weight of the correction parameter, and the weaker the correction.

7. The voltage stabilization method based on the DC bus of a frequency converter according to claim 1, characterized in that, The step of obtaining the dynamic bus voltage reference based on the operating condition data includes: S33: Determine the reference value of the DC bus based on the DC bus voltage data and the operating condition data, and then correct the reference value based on the IGBT chip junction temperature and the virtual capacitor SOC.

8. The voltage stabilization method based on the DC bus of a frequency converter according to claim 1, characterized in that, The step of determining the DC bus status based on the dynamic bus voltage reference, and controlling the charging and discharging of the virtual capacitor to stabilize the DC bus voltage based on the operating condition data and the virtual capacitor SOC, includes: S41: When regenerative energy is generated and the virtual capacitor SOC is lower than the first threshold, the regenerative energy is stored in the supercapacitor; when the virtual capacitor SOC exceeds the second threshold, the regenerative energy is switched and supplied to the auxiliary load; the first threshold is less than the second threshold.

9. The voltage stabilization method based on the DC bus of a frequency converter according to claim 1, characterized in that, After the steps of determining the DC bus status based on the dynamic bus voltage reference and controlling the charging and discharging of the virtual capacitor to stabilize the DC bus voltage based on the operating condition data and the virtual capacitor SOC, the method further includes: S50: Monitor the control effect, collect the voltage deviation, ripple coefficient, virtual capacitance SOC, and IGBT chip junction temperature of the DC bus after correction, and compare them with the control target. If the target is met, maintain the weight of the correction parameters; if the target is not met, repeat step S30 to adjust the weight of the correction parameters.

10. A voltage stabilization system based on a frequency converter DC bus, applicable to the voltage stabilization method based on a frequency converter DC bus as described in any one of claims 1 to 9, characterized in that, include: The data acquisition module is used to construct a virtual capacitor by connecting a supercapacitor in parallel with the DC bus, and to acquire DC bus voltage data, load current, energy flow direction, IGBT chip junction temperature and operating condition data. The data is preprocessed and outputs a standardized dataset. The calculation module is used to obtain virtual capacitance values ​​based on the standardized dataset, and to control the supercapacitor to correct parameters, while also obtaining the virtual capacitance SOC; The optimization module is used to obtain a dynamic bus voltage reference based on the operating condition data, obtain the corrected actual voltage deviation by combining it with the DC bus voltage, compare it with the target deviation to obtain the correction error, and then obtain the correction parameter weights by combining it with the IGBT chip junction temperature. The correction module is used to determine the DC bus status based on the dynamic bus voltage reference, and control the charging and discharging of the virtual capacitor based on the operating condition data and the virtual capacitor SOC to stabilize the DC bus voltage.

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