ASD complex working condition management method and system based on high-power active adjustable inductor

Abstract

The present application relates to the field of power electronic converter control, and discloses an ASD complex working condition management method and system based on a high-power active adjustable inductor, aiming at the problem that the fixed passive filter parameters result in poor dynamic performance and short device life under complex working conditions such as three-phase imbalance, load switching, underload and overload of ASD, the present embodiment adopts an active variable inductor with a positive inductor (such as a traditional physical inductor) and a negative inductor (single-phase inverter equivalent) in parallel; the working condition state of the ASD at the current moment is identified, and then the negative inductor inductance value is adjusted accordingly to adapt to different working conditions, so as to realize optimal filtering effect. The management method of the present embodiment can flexibly cope with complex working conditions, improve filtering performance, suppress DC side voltage fluctuation, prolong capacitor life, and at the same time improve ASD power density and operation reliability.

Description

Technical Field

[0001] This invention relates to the field of power electronic converter control, and discloses an ASD complex operating condition management method and system based on a high-power active adjustable inductor. Background Technology

[0002] An Adjustable Speed ​​Drive (ASD) comprises an economical three-phase diode bridge rectifier, a DC-DC link filter, and a three-phase inverter. It is currently widely used in motor speed control, offshore oil drilling, and other fields.

[0003] The high performance and stable operation of ASD is a prerequisite for its core role in key areas such as motor speed regulation and offshore oil drilling, and is directly related to the reliability and economy of the entire system. Once it deviates from the optimal operating conditions, under complex operating conditions such as three-phase imbalance, load switching, overload, and underload, not only will the power supply quality deteriorate significantly, but the lifespan of the devices will also be greatly shortened, triggering a chain of hidden dangers.

[0004] Existing adjustable speed drivers use traditional passive LC filter circuits on the DC side, and their circuit parameters remain fixed once put into use. Therefore, they cannot be adjusted accordingly when the ASD's operating state changes.

[0005] Under three-phase unbalanced operating conditions, amplitude and phase deviations in the grid-side voltage or current can cause asymmetrical stress on the economical three-phase diode bridge rectifier, increasing the ripple coefficient of the rectified output DC voltage and significantly raising the harmonic distortion rate (THD). This, in turn, leads to problems such as power supply voltage fluctuations and flicker, affecting the power supply stability of downstream equipment. Simultaneously, unbalanced current can cause uneven voltage and current stress on the rectifier diodes and inverter switching transistors (such as IGBTs), exacerbating localized heating, uneven temperature distribution, accelerating insulation aging and semiconductor material loss, and significantly shortening the device's lifespan.

[0006] When loads are frequently switched on and off, the system will encounter instantaneous dynamic shocks. The capacitor voltage of the DC link filter will experience sudden rises and falls, causing overvoltage and overcurrent surges, leading to a decrease in power supply transient stability and even voltage drops. These shocks will directly affect the inverter switching devices, subjecting them to instantaneous peak stresses that exceed their rated operating range. Frequent stress shocks can cause hidden damage such as device package cracking and bond wire detachment. At the same time, the charge-discharge cycles of the filter capacitors will intensify, electrolyte loss will accelerate, and capacitor life will be drastically shortened, making it a high-risk point for system failures.

[0007] When operating under overload, the driver output current far exceeds the rated value, and the power devices of the rectifier and inverter will face severe overload heat generation. If the heat dissipation system cannot dissipate the heat in time, the junction temperature of the device will quickly exceed the safety threshold, which will not only cause the supply voltage to drop and the harmonic content to surge, but also accelerate the thermal aging of semiconductor devices, causing fatal failures such as device burnout and breakdown. Long-term overload will also cause abnormal bus voltage of DC link, further deteriorating the power supply quality.

[0008] Under underload conditions, excessively low driver load can cause the inverter modulation ratio to operate in a suboptimal range, leading to increased current harmonic distortion, discontinuous current flow, and decreased power quality. Simultaneously, the proportion of switching losses in the devices increases significantly, reducing system efficiency. Prolonged low-load operation causes power devices to operate outside their optimal design conditions, resulting in increased current ripple, exacerbating electrical stress losses in the devices, and increasing the proportion of ripple current in the filter capacitors, accelerating capacitor aging and ultimately shortening device lifespan. Furthermore, the stability and accuracy of the power supply cannot be guaranteed. Summary of the Invention

[0009] The purpose of this invention is to provide a method and system for managing complex operating conditions of ASD based on a high-power active adjustable inductor. The active variable inductor enables flexible adjustment of the filter circuit parameters, which can improve filter performance, extend capacitor life, suppress DC-side voltage fluctuations of the converter, improve the reliability of the filter circuit, and increase the power density of ASD for various complex operating conditions.

[0010] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:

[0011] A method for managing complex operating conditions using an ASD (Active Variable Inductor) based on a high-power active adjustable inductor, wherein the ASD includes a drive motor, and a three-phase inverter, a three-phase uncontrolled rectifier, and an active variable inductor are arranged between the drive motor and the three-phase power grid. The input terminal of the three-phase uncontrolled rectifier is connected to the three-phase power grid and is used to convert the AC signal from the three-phase power grid to a DC signal. The three-phase inverter is used to convert the DC signal to an AC signal and output it to the drive motor. The active variable inductor includes a positive inductor, a negative inductor, and a DC power supply capacitor, with the DC power supply capacitor connected in parallel on the DC side of the negative inductor. The negative inductor includes a single-phase inverter and a filter inductor, with the single-phase inverter and the filter inductor connected in series to effectively form a negative inductor, used to adjust the overall inductance value of the parallel positive and negative inductors by adjusting the equivalent inductance value of the negative inductor. The ASD complex operating condition management method includes:

[0012] Identify the current operating status of ASD, which includes three-phase voltage imbalance, capacitor switching, load switching, overload operation, low load operation, negative inductor fault, and normal operation where the drive motor operates within a preset operating speed range.

[0013] Based on the identified operating conditions, the equivalent inductance value of the negative inductor is adjusted, where:

[0014] When the identified operating condition is normal operating condition or three-phase voltage imbalance condition, the equivalent inductance value of the negative inductor is adjusted so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range.

[0015] When the identified operating condition is capacitor switching or load switching, the inductance value of the active variable inductor is adjusted so that the DC side voltage of the three-phase uncontrolled rectifier in the ASD is within the preset voltage range.

[0016] When the identified operating condition is an overload operation, the equivalent negative inductance characteristic of the single-phase inverter is adjusted to a positive inductance characteristic until the fuse or current limiting element in the ASD trips and disconnects the load.

[0017] When the identified operating condition is low load operation, adjust the equivalent inductance value of the negative inductor to make the current of the active variable inductor non-zero.

[0018] When the identified operating condition is a negative inductor fault condition, the negative inductor is disconnected, and the positive inductor alone performs filtering.

[0019] Furthermore, methods for identifying the current operating state of ASD include:

[0020] The electrical signals of multiple detection points of the ASD are collected under different operating conditions during the test. The electrical signals include the phase voltage and current of each phase on the three-phase power grid side, as well as the current of the active variable inductor, the current of the negative inductor, the DC side capacitor voltage of the negative inductor, and the current of the filter capacitor in the filter circuit.

[0021] Using the electrical signal at the detection point as input and the corresponding operating conditions as output, an analytical model for predicting the operating state of ASD is established based on a neural network model.

[0022] The electrical signals of each detection point are collected in real time during the operation of the ASD. Based on the electrical signals collected during operation, the analysis model is used to identify the current operating status of the ASD.

[0023] Furthermore,

[0024] When the identified operating condition is a three-phase voltage imbalance condition, the overall inductance is increased by reducing the negative inductance value, so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range.

[0025] When the identified operating condition is capacitor switching, the overall inductance is increased by reducing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in ASD is within the preset voltage range.

[0026] When the identified operating condition is low load operation, the overall inductance is increased by reducing the negative inductance value, so that the current of the active variable inductor is not zero.

[0027] When the identified operating condition is load switching, the overall inductance is reduced by increasing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in ASD is within the preset voltage range.

[0028] Furthermore, the single-phase inverter includes four switching transistors, namely the first switching transistor. Second switching transistor Third switching transistor Fourth switching transistor All four switching transistors are insulated-gate bipolar transistors, wherein:

[0029] The gates of the four switching transistors are connected to the gate drive control signal. Power diodes are connected in parallel across the two ends of each of the four switching transistors. The collector of each switching transistor is connected to the negative terminal of the diode, and the emitter of each switching transistor is connected to the positive terminal of the diode.

[0030] First switching transistor and the third switching transistor Series connection, and the first switch transistor The emitter is connected to the third switching transistor. The collector; the second switching transistor and the fourth switching transistor Series connection, and the second switch The emitter is connected to the fourth switching transistor. The collector; the first switching transistor The collector is connected to the second switching transistor. The collector of the third switching transistor The emitter is connected to the fourth switching transistor. The emitter;

[0031] DC power supply capacitor Both ends are connected to the first switching transistor. collector and third switching transistor The emitter, the second switching transistor The collector is connected to the DC power supply capacitor. The positive terminal, the fourth switching transistor The emitter is connected to the DC power supply capacitor. The negative electrode;

[0032] The positive inductor The two ports are respectively ports and Port, filter inductor One end is connected to the first switching transistor The emitter of one end is connected to the positive inductor as a port of the negative inductor. The ports are connected, the Port and fourth switch The collectors are connected.

[0033] To achieve the above technical effects, the present invention also provides an ASD complex operating condition management system based on a high-power active adjustable inductor. The ASD includes a drive motor, and a three-phase inverter, a three-phase uncontrolled rectifier, and an active variable inductor are arranged between the drive motor and the three-phase power grid side. The input terminal of the three-phase uncontrolled rectifier is connected to the three-phase power grid side to convert the AC signal from the three-phase power grid side into a DC signal. The three-phase inverter is used to convert the DC signal into an AC signal and output it to the drive motor. The active variable inductor includes a positive inductor, a negative inductor, and a DC power supply capacitor, with the DC power supply capacitor connected in parallel on the DC side of the negative inductor. The negative inductor includes a single-phase inverter and a filter inductor, with the single-phase inverter and the filter inductor connected in series to effectively form a negative inductor, used to adjust the overall inductance value of the parallel positive and negative inductors by adjusting the equivalent inductance value of the negative inductor. The ASD complex operating condition management system includes:

[0034] The operating condition identification module is used to identify the current operating condition of the ASD. The operating condition includes normal operation, three-phase voltage imbalance, capacitor switching, load switching, overload operation, low load operation, negative inductor fault, and normal operation when the drive motor is running within a preset operating speed range.

[0035] The equivalent inductance adjustment module is used to adjust the equivalent inductance of the negative inductance based on the identified operating conditions, wherein:

[0036] When the identified operating condition is normal operating condition or three-phase voltage imbalance condition, the equivalent inductance value of the negative inductor is adjusted so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range.

[0037] When the identified operating condition is capacitor switching or load switching, the inductance value of the active variable inductor is adjusted so that the DC side voltage of the three-phase uncontrolled rectifier in the ASD is within the preset voltage range.

[0038] When the identified operating condition is an overload operation, the equivalent negative inductance characteristic of the single-phase inverter is adjusted to a positive inductance characteristic until the fuse or current limiting element in the ASD trips and disconnects the load.

[0039] When the identified operating condition is low load operation, adjust the equivalent inductance value of the negative inductor to make the current of the active variable inductor non-zero.

[0040] When the identified operating condition is a negative inductor fault condition, the negative inductor is disconnected, and the positive inductor filters the signal separately.

[0041] Furthermore, the working condition identification module includes:

[0042] The data acquisition unit is used to acquire electrical signals from multiple detection points of the ASD under different operating conditions during the test. The electrical signals include the phase voltage and current of each phase on the three-phase power grid side, as well as the current of the active variable inductor, the current of the negative inductor, the DC-side capacitor voltage of the negative inductor, and the current of the filter capacitor in the filter circuit.

[0043] The prediction model building unit is used to build an analysis model based on a neural network model to predict the working state of ASD, with the electrical signal of the detection point as input and the corresponding working condition as output.

[0044] The predictive analysis unit is used to identify the current operating condition of the ASD based on the electrical signals of each detection point collected in real time during the operation of the ASD using the analysis model.

[0045] Furthermore, in the equivalent perception value adjustment module:

[0046] When the identified operating condition is a three-phase voltage imbalance condition, the overall inductance is increased by reducing the negative inductance value, so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range.

[0047] When the identified operating condition is capacitor switching, the overall inductance is increased by reducing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in ASD is within the preset voltage range.

[0048] When the identified operating condition is low load operation, the overall inductance is increased by reducing the negative inductance value, so that the current of the active variable inductor is not zero.

[0049] When the identified operating condition is load switching, the overall inductance is reduced by increasing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in ASD is within the preset voltage range.

[0050] Furthermore, the single-phase inverter includes four switching transistors, namely the first switching transistor. Second switching transistor Third switching transistor Fourth switching transistor All four switching transistors are insulated-gate bipolar transistors, wherein:

[0051] The gates of the four switching transistors are connected to the gate drive control signal. Power diodes are connected in parallel across the two ends of each of the four switching transistors. The collector of each switching transistor is connected to the negative terminal of the diode, and the emitter of each switching transistor is connected to the positive terminal of the diode.

[0052] First switching transistor and the third switching transistor Series connection, and the first switch transistor The emitter is connected to the third switching transistor. The collector; the second switching transistor and the fourth switching transistor Series connection, and the second switch The emitter is connected to the fourth switching transistor. The collector; the first switching transistor The collector is connected to the second switching transistor. The collector of the third switching transistor The emitter is connected to the fourth switching transistor. The emitter;

[0053] DC power supply capacitor Both ends are connected to the first switching transistor. collector and third switching transistor The emitter, the second switching transistor The collector is connected to the DC power supply capacitor. The positive terminal, the fourth switching transistor The emitter is connected to the DC power supply capacitor. The negative electrode;

[0054] The positive inductor The two ports are respectively ports and Port, filter inductor One end is connected to the first switching transistor The emitter of one end is connected to the positive inductor as a port of the negative inductor. The ports are connected, the Port and fourth switch The collectors are connected.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention can address the problem of poor dynamic performance and short device life caused by fixed passive filter parameters under complex operating conditions such as three-phase imbalance, load switching, and overload in ASD. By adjusting the negative inductance value, it can flexibly cope with complex operating conditions, improve filter performance, suppress DC side voltage fluctuations, extend capacitor life, and improve ASD power density and operational reliability. Attached Figure Description

[0056] Figure 1 This is a schematic diagram illustrating the application of the ASD complex operating condition management method and system;

[0057] Figure 2 This is the structure and control block diagram of an active negative inductor;

[0058] Figure 3 Under normal operating conditions The DC-side capacitor voltage and inductor current at that time;

[0059] Figure 4 This is the waveform of passive inductor filtering under unbalanced operating conditions;

[0060] Figure 5 It is the waveform of an active variable inductor filter with positive and negative parallel connection under unbalanced operating conditions;

[0061] Figure 6 This is a spectrum analysis of the overall inductor current after parallel connection under unbalanced operating conditions;

[0062] Figure 7 It is the DC-side voltage of the rectifier under capacitor switching conditions;

[0063] Figure 8 It is the DC-side power supply capacitor voltage of the active variable inductor under capacitor switching conditions;

[0064] Figure 9 This is the DC-side voltage waveform of the rectifier under load switching conditions;

[0065] Figure 10 It is the current waveform of the active variable inductor under load switching conditions;

[0066] Figure 11 It shows the current waveforms in active variable inductors and passive inductors under overload conditions.

[0067] Figure 12 These are the current waveforms in the positive and negative inductors of an active variable inductor under overload conditions.

[0068] Figure 13 It is the current waveform of the positive inductor in a passive inductor and an active variable inductor under overload conditions;

[0069] Figure 14It is the current waveform of an active variable inductor under low load conditions;

[0070] Figure 15 It is the current of the active variable inductor under negative inductance fault conditions;

[0071] Figure 16 It is the DC-side capacitor voltage of the active variable inductor under negative inductance fault conditions;

[0072] Figure 17 It is the current waveform of the positive and negative inductors in an active variable inductor under negative inductor fault conditions. Detailed Implementation

[0073] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0074] Example 1

[0075] See Figure 1 , Figure 2 A method for managing complex operating conditions using an Active Variable Inductor (ASD) based on a high-power active adjustable inductor is disclosed. The ASD includes a drive motor. A three-phase inverter, a three-phase uncontrolled rectifier, and an active variable inductor are installed between the drive motor and a three-phase power grid. The input of the three-phase uncontrolled rectifier is connected to the three-phase power grid and is used to convert the AC signal from the three-phase power grid into a DC signal. The three-phase inverter is used to convert the DC signal back to AC and output it to the drive motor. The active variable inductor includes a positive inductor, a negative inductor, and a DC power supply capacitor, with the DC power supply capacitor connected in parallel on the DC side of the negative inductor. The negative inductor includes a single-phase inverter and a filter inductor, with the single-phase inverter and the filter inductor connected in series to effectively form a negative inductor, allowing the overall inductance value of the parallel positive and negative inductors to be adjustable by adjusting the equivalent inductance value of the negative inductor. The ASD complex operating condition management method includes:

[0076] Identify the current operating status of ASD, which includes three-phase voltage imbalance, capacitor switching, load switching, overload operation, low load operation, negative inductor fault, and normal operation where the drive motor operates within a preset operating speed range.

[0077] Based on the identified operating conditions, the equivalent inductance value of the negative inductor is adjusted, where:

[0078] When the identified operating condition is normal operating condition or three-phase voltage imbalance condition, the equivalent inductance value of the negative inductor is adjusted so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range.

[0079] When the identified operating condition is capacitor switching or load switching, the inductance value of the active variable inductor is adjusted so that the DC side voltage of the three-phase uncontrolled rectifier in the ASD is within the preset voltage range.

[0080] When the identified operating condition is an overload operation, the equivalent negative inductance characteristic of the single-phase inverter is adjusted to a positive inductance characteristic until the fuse or current limiting element in the ASD trips and disconnects the load.

[0081] When the identified operating condition is low load operation, adjust the equivalent inductance value of the negative inductor until the current of the active variable inductor is not zero.

[0082] When the identified operating condition is a negative inductor fault condition, the negative inductor is disconnected, and the positive inductor alone performs filtering.

[0083] To address the issues of poor dynamic performance and short device lifespan caused by fixed passive filter parameters in complex operating conditions such as three-phase imbalance, load switching, and overload, this embodiment employs an active variable inductor connected in parallel with a positive inductor (such as a traditional physical inductor) and a negative inductor (equivalent to a single-phase inverter). By identifying the current operating state of the ASD, the inductance value of the negative inductor is adjusted accordingly to adapt to different operating conditions and achieve optimal filtering performance. This management method can flexibly handle complex operating conditions, improve filtering performance, suppress DC-side voltage fluctuations, extend capacitor life, and simultaneously increase the ASD's power density and operational reliability.

[0084] like Figure 1 As shown, in some other embodiments, the method for identifying the current operating state of ASD includes:

[0085] The electrical signals of multiple detection points of the ASD are collected under different operating conditions during the test. The electrical signals include the phase voltage and current of each phase on the three-phase power grid side, as well as the current of the active variable inductor, the current of the negative inductor, the DC side capacitor voltage of the negative inductor, and the current of the filter capacitor in the filter circuit.

[0086] Using the electrical signal at the detection point as input and the corresponding operating conditions as output, an analytical model for predicting the operating state of ASD is established based on a neural network model.

[0087] The electrical signals of each detection point are collected in real time during the operation of the ASD. Based on the electrical signals collected during operation, the analysis model is used to identify the current operating status of the ASD.

[0088] Example 2

[0089] A method for managing complex operating conditions using an ASD (Active Variable Inductor) based on a high-power active adjustable inductor, wherein the ASD includes a drive motor, and a three-phase inverter, a three-phase uncontrolled rectifier, and an active variable inductor are arranged between the drive motor and the three-phase power grid. The input terminal of the three-phase uncontrolled rectifier is connected to the three-phase power grid and is used to convert the AC signal from the three-phase power grid to a DC signal. The three-phase inverter is used to convert the DC signal to an AC signal and output it to the drive motor. The active variable inductor includes a positive inductor, a negative inductor, and a DC power supply capacitor, with the DC power supply capacitor connected in parallel on the DC side of the negative inductor. The negative inductor includes a single-phase inverter and a filter inductor, with the single-phase inverter and the filter inductor connected in series to effectively form a negative inductor, used to adjust the overall inductance value of the parallel positive and negative inductors by adjusting the equivalent inductance value of the negative inductor. The ASD complex operating condition management method includes:

[0090] Step 1: Identify the current operating status of ASD. The operating status includes three-phase voltage imbalance, capacitor switching, load switching, overload operation, low load operation, negative inductor fault, and normal operation where the drive motor operates within the preset operating speed range.

[0091] In this embodiment, taking the seven operating modes of the ASD shown in Table 1 as an example, the identification method of the operating state of the ASD is explained in detail. In Table 1, operating mode 1 is the normal operating mode; the operating state changes caused by the grid side are mainly operating mode 2 (three-phase voltage imbalance) and operating mode 3 (capacitor switching). The operating state changes caused by the load side are mainly operating mode 4 (load switching), operating mode 5 (overload operation), and operating mode 6 (low load operation). When using the equivalent overall inductance of active devices, considering the faults in the power electronic circuit, the relevant analysis of operating mode 7 (negative inductor fault condition) is also performed.

[0092] Table 1 List of Operating Modes

[0093]

[0094] Working condition pattern recognition based on neural networks:

[0095] 1.1 Acquire electrical signals from multiple detection points of the ASD under different operating conditions during the test; the electrical signals include the phase voltage and current of each phase on the three-phase power grid side, as well as the current of the active variable inductor, the current of the negative inductor, the DC-side capacitor voltage of the negative inductor, and the current of the filter capacitor in the filter circuit;

[0096] In this embodiment, as Figure 1 , Figure 2 As shown, the grid-side voltage is synchronously collected via sensors. and current Load-side current and rectifier DC output The current of the filter capacitor in the filter circuit Active inductor current Negative inductance current DC side capacitor voltage of negative inductor Multi-dimensional time-domain signals are processed using digital filtering to remove noise interference. Data dimensions are normalized to eliminate the influence of signal amplitude differences, generating a well-organized original feature dataset.

[0097] 1.2 Using the electrical signal of the detection point as input and the corresponding working condition as output, an analytical model for predicting the working condition of ASD is established based on a neural network model;

[0098] 1.2.1 Align the preprocessed voltage and current signals according to the time series, extract time-domain statistical features (such as peak value, RMS value, ripple coefficient) or directly construct multi-dimensional feature vectors, covering key electrical parameters of the grid side, load side, and filter circuit, to form input samples for the neural network.

[0099] 1.2.2 Divide the training set and validation set, construct a neural network adapted for working condition recognition. Using the labeled working condition patterns as labels, iteratively optimize the network weights and biases through the backpropagation algorithm, minimize the prediction loss function, verify the model's generalization ability, and fine-tune the hyperparameters to complete the training of the analysis model (i.e., the working condition recognition model).

[0100] 1.3 Real-time acquisition of electrical signals at each detection point during ASD operation; based on the acquired electrical signals, the analysis model is used to identify the current operating status of ASD.

[0101] In this embodiment, the multi-feature vectors that are collected and preprocessed in real time are input into the trained neural network. The probability of the output working condition category is calculated through forward propagation. The working condition mode of the current ASD system is determined based on the maximum probability, so as to achieve rapid and accurate identification of the working condition.

[0102] Step 2: Adjust the equivalent inductance value of the negative inductor based on the identified operating conditions. The adjustment logic for each operating condition is as follows:

[0103] 2.1) When the identified operating condition is normal operating condition or three-phase voltage imbalance condition, adjust the equivalent inductance value of the negative inductor so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range.

[0104] If identified as operating condition 1—normal operating condition:

[0105] For an active inductor, there is only one control parameter, namely the equivalent inductance value of the negative inductor. Under normal operating conditions, This involves maintaining the current ripple flowing through the active inductor at a reasonable level. The reference value for the current ripple of the active variable inductor is set. By controlling the current flowing through the active variable inductor Peak extraction is performed to obtain the actual current ripple. Therefore, the equivalent inductance value of the negative inductor is calculated. Adjustment:

[0106] With current ripple reference value Compared to actual current ripple Based on the deviation, the control precision is set (the difference between the current ripple after the system stabilizes and the target current ripple). When the deviation is less than the control precision, the system reaches stability, and the control parameters remain unchanged to avoid frequent adjustments caused by small fluctuations; when the deviation is greater than the control precision, the control parameters are adjusted.

[0107] Regarding the adjustment direction of the control parameters, the adjustment trend of the output value is determined according to the direction of the deviation: if the target current ripple is higher than the actual current ripple, the control... Adjust in the direction of increase; if the target current ripple is lower than the actual current ripple, control... Adjust in the direction of decreasing.

[0108] During the adjustment process, control parameters It should be limited to the preset upper and lower limits to ensure that it is within a reasonable working range and avoids exceeding the boundaries allowed by the system.

[0109] The adjustment rate of the control parameter is related to the current inductance value of the negative inductor and exhibits a continuously changing trend: currently... When the value is large, the adjustment speed is faster; currently When the value is small, the adjustment speed is slow. The adjustment rate is based on the midpoint of the preset adjustable range of negative inductance value, forming a smooth rate characteristic throughout the entire adjustment range.

[0110] If identified as operating condition 2—three-phase voltage imbalance condition:

[0111] When a three-phase voltage imbalance occurs, the DC-side active variable inductor current will exhibit a second-harmonic frequency fluctuation. This can be addressed by adjusting... By increasing the overall inductance value, current changes are hindered, and the inductor's impedance to frequency fluctuations is increased, slowing down the rate of current change and thus reducing the amplitude of second harmonic fluctuations. A larger inductance value can synergize with the voltage loop of the active inductor, ensuring that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within a preset first deviation range. This better smooths the current, absorbs low-frequency pulsations, and mitigates the adverse effects of three-phase voltage imbalance on DC-side operating conditions.

[0112] 2.2) When the identified operating condition is capacitor switching or load switching, adjust the inductance value of the active variable inductor to keep the DC side voltage of the three-phase uncontrolled rectifier in the ASD within the preset voltage range.

[0113] If identified as operating condition 3—capacitor switching operating condition:

[0114] In order to compensate for reactive power, improve the power factor, reduce line losses, stabilize system voltage, and improve the transmission efficiency and power quality of the power system, capacitor banks are put into operation.

[0115] When the capacitor bank is switched on, the rectifier output voltage will experience overshoot. Switching the capacitor bank causes instantaneous fluctuations in the mains voltage. When the voltage rises momentarily, the rectified DC voltage rises synchronously. Simultaneously, the capacitors in the LC filter circuit have energy storage characteristics, which further amplify the voltage fluctuations. The resonant current must be absorbed by the DC bus capacitor, thus generating overvoltage. Therefore, it is necessary to suppress high voltage by absorbing high-frequency current and reducing overvoltage.

[0116] In specific operation, by adjusting There are two main reasons for increasing the overall inductance value: First, the core characteristic of an inductor is to impede sudden current changes; a larger inductance value results in stronger suppression of instantaneous charging current, significantly slowing down the current rise rate and reducing the peak inrush current. Second, increasing the inductance value can change the resonant frequency of the LC circuit, shifting it lower and away from the high-frequency harmonic band during charging surges, thus avoiding the amplification of voltage fluctuations due to resonance. Additionally, appropriately increasing the capacitor reference voltage on the DC side of the negative inductor buffers the impact of the inverter-side resonant current on the DC bus.

[0117] If identified as operating condition 4—load switching operating condition:

[0118] When the load current increases, the DC-side voltage will drop; when the load current decreases, it will overshoot. Suppressing this voltage fluctuation requires adjustment. This reduces the overall inductance, improves the current response speed, and suppresses voltage dips and overshoots.

[0119] An increase in load current means a surge in energy demand. The DC-side filter capacitor needs to quickly release its charge to fill the current gap. If the capacitor's discharge rate exceeds its charging rate within a short period, the voltage will inevitably drop. The inductor current cannot change instantaneously. At its original inductance value, the inductor cannot quickly increase its current output to match the load demand, resulting in a temporary shortage of DC-side power supply capacity, which further exacerbates the voltage drop.

[0120] When the load current decreases, the energy demand suddenly drops, but the rectifier bridge continues to output power. The excess power cannot be fully absorbed by the load and can only charge the DC-side filter capacitor, causing the capacitor voltage to rise. The current inertia of the inductor prevents the current from decreasing synchronously with the load demand. The excess inductor current will continue to charge the capacitor, further pushing up the capacitor voltage and creating an overshoot, thus keeping the DC-side voltage within the preset range.

[0121] Furthermore, the inductor's ability to impede current changes is positively correlated with its inductance value. Reducing the inductance value decreases its resistance to sudden current changes, allowing the inductor current to follow load current changes more quickly. When the current increases, the inductor can quickly boost the current output to compensate for insufficient capacitor discharge; when the current decreases, the inductor can quickly discharge excess current, preventing overcharging of the capacitor. Smaller inductance values ​​result in faster dynamic response, shortening the transition time from "load surge" to "energy rebalancing," reducing the duration of voltage dips or overshoots, and mitigating the impact of disturbances. Reducing the inductance value optimizes the dynamic matching characteristics of LC filter circuits, making the charging and discharging of the capacitor more coordinated with the energy storage and release of the inductor, avoiding energy accumulation or supply lag caused by excessive inductor inertia, and fundamentally suppressing the magnitude of voltage deviation from the steady-state value.

[0122] 2.3) When the identified operating condition is an overload operating condition, the equivalent negative inductance characteristic of the single-phase inverter is adjusted to a positive inductance characteristic until the fuse or current limiting element in the ASD trips and disconnects the load.

[0123] Overload causes the inductor current to far exceed the rated value, resulting in a surge in copper losses, hysteresis, and eddy current losses. This leads to inductor overheating, accelerated winding insulation aging, and even short circuits. The magnetic core easily reaches saturation, causing a sharp drop in inductance, failure of filtering and harmonic suppression capabilities, and increased DC-side voltage ripple. Simultaneously, the strong electromagnetic force generated by the high current induces winding vibration and core loosening, shortening inductor lifespan and potentially causing LC circuit resonant frequency shifts and amplifier circuit disturbances.

[0124] When the load current and the current in the filter inductor are detected to exceed the rated value, the inductance value of the negative inductor is controlled. This causes the single-phase inverter to exhibit the characteristics of a positive inductor, thereby shunting the current from the positive inductor and reducing the current in the filters of the positive and negative inductors, thus buying time for the fuse or current-limiting element to operate.

[0125] 2.4) When the identified operating condition is low load operation, increase the overall inductance value of the active variable inductor until the current of the active variable inductor is not zero.

[0126] When the load power is too low, the inductor current will become discontinuous. The core reason for this is that the inductor's energy storage is insufficient to maintain continuous power supply. This phenomenon will exacerbate filter losses and deteriorate the stability of the load power supply, requiring an increase in the inductance value of the active variable inductor to suppress discontinuity.

[0127] The output current of a three-phase uncontrolled rectifier inherently exhibits pulsating characteristics. In a passive LC filter circuit, the core function of the inductor is to fill the gaps in the rectified current pulsation by storing and releasing electromagnetic energy, thus maintaining continuous DC current. When the load power is too low, the current demanded by the load decreases significantly, and the peak value of the pulsating current output by the rectifier bridge decreases accordingly, resulting in a significant deficiency of the electromagnetic energy stored in the inductor. Between adjacent pulsating cycles of the rectifier output current, the energy released by the inductor is quickly depleted, unable to continuously supply energy to the load and capacitor, causing the inductor current to interrupt between two pulsating cycles, forming an intermittent current pattern.

[0128] Discontinuous current is extremely harmful. For LC filters, discontinuous inductor current increases core losses, causes heating and aging, disrupts capacitor charging and discharging, dramatically increases voltage ripple, shortens lifespan, and may even induce LC resonance, exacerbating component losses. For loads, excessive supply voltage ripple and decreased stability affect the accuracy of sensitive loads, even causing malfunctions, increasing load losses, reducing efficiency, and in severe cases, leading to load failure.

[0129] The adjustment logic under this operating condition is to increase the inductance value of the active variable inductor, for two main reasons. First, the energy storage capacity of an inductor is positively correlated with its inductance value. Increasing the inductance value significantly improves the inductor's energy storage capacity. Even under low load conditions with a low peak rectified current, a large-value inductor can store enough electromagnetic energy to smoothly support the next rectified pulsation cycle, filling the energy supply gap and fundamentally preventing current interruption, thus achieving continuous operation. Second, a large-value inductor has stronger current inertia, which slows down the rate of current decay. Under low load conditions, even if the rectified current enters a pulsation trough, the inductor current will not drop to zero quickly, but will decay at a gradual rate, maintaining continuous flow and avoiding current interruption.

[0130] 2.5) When the identified operating condition is a negative inductor fault condition, disconnect the negative inductor and let the positive inductor perform filtering alone;

[0131] The negative inductance in an active variable inductor is derived from the equivalent of a single-phase inverter. Considering that common faults of single-phase inverters include power device breakdown, abnormal drive module and controller, inverter bridge imbalance, protection circuit malfunction, and heat dissipation system failure, the operational stability of the LC filter circuit will be affected.

[0132] The system detects the DC-side voltage and output current of the negative inductor, as well as the current in the active variable inductor. In case of an abnormality, the negative inductor is disconnected, and the positive inductor alone performs filtering to maintain the minimum current ripple requirement.

[0133] The application diagram of the high-power active variable inductor in the adjustable speed driver in this embodiment is shown below. Figure 1As shown: The Adjustable Speed ​​Drive (ASD) includes an economical three-phase diode bridge rectifier, a DC-DC link filter, and a three-phase inverter; in the passive inductor, i.e., the positive inductor... By connecting a negative inductor in parallel across the two ends, a larger inductance value is obtained, resulting in better filtering performance, thereby reducing the size of the active variable inductor and increasing power density. Simultaneously, by adjusting the inductance value of the negative inductor, the overall inductance value of the parallel circuit changes, enabling flexible adjustment of the active variable inductor.

[0134] Specifically, it also includes an MCU controller, a PI controller, and an AD converter; the AD converter includes a first AD converter, a second AD converter, and a third AD converter; the first AD converter is connected to the negative inductor. A first converter is used to acquire the current of the negative inductor and convert it into a first digital signal; a second analog-to-digital converter is used to acquire the current of the positive inductor. The voltage signal between the two ports is converted into a second digital signal; the third AD analog-to-digital converter is used to convert the DC power supply capacitor The analog voltage signals at both ends are converted into a third digital signal;

[0135] The PI controller receives the third digital signal and adjusts the virtual resistance of the negative inductor according to the third digital signal, so that the DC side voltage... The deviation from the voltage reference value is within a preset first deviation range;

[0136] The MCU controller is used to receive the first digital signal and the second digital signal, and generate a negative inductance based on the current ripple in the active variable inductor. The sensing value; and the virtual resistance adjusted by the PI controller. Pressure drop is obtained Combined with negative inductance Sensitivity and voltage drop This yields control signals for the four switching transistors.

[0137] The single-phase inverter (in this embodiment, an H-bridge is used) includes four switching transistors, namely the first switching transistor. Second switching transistor Third switching transistor Fourth switching transistor All four switching transistors are insulated-gate bipolar transistors, wherein:

[0138] The gates of the four switching transistors are connected to the gate drive control signal. Power diodes are connected in parallel across the two ends of each of the four switching transistors. The collector of each switching transistor is connected to the negative terminal of the diode, and the emitter of each switching transistor is connected to the positive terminal of the diode.

[0139] First switching transistor and the third switching transistor Series connection, and the first switch transistor The emitter is connected to the third switching transistor. The collector; the second switching transistor and the fourth switching transistor Series connection, and the second switch The emitter is connected to the fourth switching transistor. The collector; the first switching transistor The collector is connected to the second switching transistor. The collector of the third switching transistor The emitter is connected to the fourth switching transistor. The emitter;

[0140] DC power supply capacitor Both ends are connected to the first switching transistor. collector and third switching transistor The emitter, the second switching transistor The collector is connected to the DC power supply capacitor. The positive terminal, the fourth switching transistor The emitter is connected to the DC power supply capacitor. The negative electrode;

[0141] The positive inductor The two ports are respectively ports and Port, filter inductor One end is connected to the first switching transistor The emitter of one end is connected to the positive inductor as a port of the negative inductor. The ports are connected, the Port and fourth switch The collectors are connected.

[0142] A single-phase inverter consists of four switching transistors. During normal operation, the control signal controls the first switching transistor to be in its first state. and the fourth switching transistor Simultaneously, the second switching transistor is turned on. and the third switching transistor Off; the second state is the switching transistor. and switching transistor Turn off, switching transistor and switching transistor Simultaneous conduction, with the two states alternating cyclically, makes the port... , The excitation voltage and port current at both ends conform to the characteristics of a negative inductor.

[0143] The inductance value of the positive inductor in the active inductor is selected based on the maximum DC-side current ripple allowed by ASD. This ensures that when a negative inductor fault is cleared, the entire system can operate at the minimum power quality standard without failing.

[0144] This embodiment of the control method for a high-power active variable inductor mainly includes three parts: a voltage loop, a control parameter generation loop, and a current loop. The voltage loop charges the DC capacitor of the single-phase inverter, keeping the voltage across the capacitor constant, thus acting as a DC source. The control parameter generation loop generates parameters based on the output current of the active inductor. The peak-to-peak value of the current ripple, combined with the peak-to-peak value of the target current ripple, affects the inductance of the negative inductor. Adjustments are made to change the overall inductance value of the active inductor, thereby adjusting its suppression effect on current ripple. The specific control method is as follows:

[0145] Step 1: Real-time acquisition of DC side voltage of negative inductor Negative inductor port voltage and negative inductor current Analysis to obtain DC side voltage The second difference between the voltage and the preset voltage reference value;

[0146] Step 2: Based on the second difference, use a PI controller to adjust the virtual resistance of the negative inductor to compensate for the negative inductor loss, so that the DC side voltage... The deviation from the voltage reference value is within a preset second deviation range;

[0147] In this embodiment, the PI controller adjusts the virtual resistance of the negative inductor to a target value of... ,in For the virtual resistance target value, This is the reference value for the DC power supply capacitor voltage on the DC side. These are the integral parameters of the PI controller. The proportional parameter of the PI controller, It is a complex frequency variable.

[0148] Step 3: Real-time acquisition of positive inductance current Extracting the current ripple of an active variable inductor According to current ripple Compared with the preset current ripple reference value The first difference between them is adjusted by the MCU controller using the negative inductance. The inductance value makes the current ripple Compared with the preset current ripple reference value The first difference between them is within the preset first deviation range;

[0149] In this embodiment, the inductance value of the positive inductor is assumed to be... Based on the properties of a negative inductor, the overall equivalent inductance value after connecting positive and negative inductors in parallel can be obtained. When the positive inductance is fixed, as the inductance of the negative inductance gradually decreases and approaches the inductance of the positive inductance, the overall equivalent inductance... The rate of increase is getting larger and larger. When hour, Approaching Therefore, it is evident that the parallel connection of a negative inductor and a positive inductor can significantly increase the equivalent inductance, thereby greatly improving power density and power quality. For active inductors, there is only one control parameter: the equivalent inductance of the negative inductor. Under normal operating conditions, the equivalent sensing value of the control... It can maintain the current ripple flowing through the active inductor at a reasonable level. Set the current ripple reference value. The current flowing through the active inductor is detected by a peak detection circuit. Peak extraction is performed to obtain the actual current ripple. Therefore, the MCU controller determines how to adjust the control parameters. .

[0150] The control precision (the difference between the current ripple after system stabilization and the target current ripple) is set based on the deviation between the current ripple reference value and the actual current ripple. When the deviation is less than the control precision, the system reaches stability, and the control parameters remain unchanged to avoid frequent adjustments caused by small fluctuations; when the deviation is greater than the control precision, the control parameters are adjusted.

[0151] Regarding the adjustment direction of the control parameters, the adjustment trend of the output value is determined according to the direction of the deviation: if the target current ripple is higher than the actual current ripple, the control parameters are adjusted in the direction of increasing; if the target current ripple is lower than the actual current ripple, the control parameters are adjusted in the direction of decreasing.

[0152] The control parameters are always limited to the preset upper and lower limits to ensure that they are within a reasonable operating range and to avoid exceeding the system's allowed boundaries.

[0153] The adjustment rate of the control parameter is related to the current inductance value of the negative inductor and shows a continuous changing trend: when the current control parameter is large, the adjustment speed is fast; when the current output value is small, the adjustment speed is slow. Based on the adjustment rate at the midpoint of the preset adjustable range of the negative inductor value, a smooth rate characteristic is formed throughout the entire adjustment range.

[0154] During the adjustment process, based on the initial value set by the negative inductance, and considering the adjustment direction and rate, the control parameters are updated in real time using the disturbance observation method. The specific adjustment procedure is as follows:

[0155] Step 3.1: Adjust the virtual resistance according to the PI controller. and negative inductance Port voltage Current Analysis yields negative inductance The voltage drop of the actual equivalent inductance ;

[0156] In this embodiment, the negative inductor The voltage drop of the actual equivalent inductance is based on The results were obtained through analysis.

[0157] Step 3.2: Based on the negative inductance The voltage drop of the actual equivalent inductance and the required negative inductance Sensitivity Analysis yields negative inductance The reference current for the output current;

[0158] In this embodiment, the negative inductor The reference current for the output current is based on Analysis yielded, among which The reference current is... Voltage drop of actual equivalent inductance The expression function in the frequency domain, It is a complex frequency variable.

[0159] Step 3.3: Based on the reference current, employ Finite Set Model Predictive Control (FCS-MPC) and select a negative inductor. The switching state with the smallest output current tracking error is selected, and control signals for the four switching transistors are output to adjust the negative inductor. The sensitivity value;

[0160] In this embodiment, the port output current is first measured in each sampling period. Sampling is performed, and the sampling results are then input into the MCU controller, combined with the output results of the voltage loop. A current reference value can be obtained. .

[0161] When the sampling frequency is low, the current reference value should be used for prediction. The reference value at that location. Lagrange extrapolation can be used for prediction. The current reference value at that location, its general expression is:

[0162]

[0163] in

[0164]

[0165] It is the order of the Lagrange extrapolation method. For the summation index, , k This is a discrete-time index, representing the current sampling time. For sinusoidal reference values, It is usually set to 2. This allows us to obtain the predicted reference current value for the next moment.

[0166] Then, based on all the switching states of the switching equipment, a finite control set of the inverter is determined, and the correspondence between all valid switching states and output voltage is established, as shown in Table 2.

[0167] In Table 2, it is assumed that... - It is an ideal switching device with only two states (on and off). The switching state is represented by the state symbol: This indicates that the device is conducting. This indicates the device is off. Because the DC link cannot be short-circuited, the upper and lower switches on the same bridge arm cannot be turned on simultaneously. After eliminating the invalid states that would cause breakdown, the number of valid switch states is 4. The inverter output voltage corresponding to each state is expressed as follows: .

[0168] Table 2 Effective Switching Status of Bridge H

[0169]

[0170] The prediction model for the output current of a single-phase inverter is established as follows:

[0171]

[0172] in It is the sampling period. The output voltage of a single-phase inverter At sampling time The value, Port voltage of a single-phase inverter At sampling time The value, The inductance value of the filter inductor is determined by... and By sampling and combining these samples with inverter system parameters, multiple predicted values ​​of the output current can be obtained. .

[0173] Finally, define the cost function. And select the optimal switching state.

[0174]

[0175] Based on the cost function, determine the optimal switching state for the next instant.

[0176] To verify the feasibility of the management method in this embodiment, according to Figure 1 and Figure 2 Set up the simulation module in PSIM, set the predetermined control parameters according to Table 3, and start running the simulation.

[0177] Table 3 Simulation Experiment Parameter Table

[0178]

[0179] The simulation results for each working condition are as follows, based on the simulation analysis:

[0180] Operating Condition 1:

[0181] In the adjustable speed driver, the passive inductor was replaced with an active variable filter. The experimental parameters are shown in Table 3. Case I As shown. The target current ripple (i.e., the current ripple reference value) is set to 0.5A, with a first deviation range of ±6%. Simulation results show that the current in the active variable inductor... like Figure 3 As shown, the DC-side power supply capacitor voltage is stable at around 100V with a fluctuation range of 0.859V, the current ripple is 0.526A, and the control error is 5.2%.

[0182] Operating Condition 2:

[0183] The target current ripple is 1A. A passive inductor of 33.7mH and an active inductor are used for comparative experiments. The parameters are shown in Table 3. Case I When t=5s, a three-phase voltage imbalance of 5% occurs. The filtering effect of the passive inductor is as follows: Figure 4 As shown, the current ripple increased from 0.96 A to 2.16 A.

[0184] When a voltage imbalance occurs, if the detected current ripple is higher than the target value, the current ripple is suppressed to the target value by increasing the inductance of the active inductor; for example... Figure 5 As shown, the current ripple before and after the three-phase unbalanced condition is 1.03 A and 1.15 A, respectively.

[0185] like Figure 6 As shown, when three-phase imbalance occurs, passive inductors cannot effectively suppress the 100Hz harmonics introduced by the unbalanced voltage. In this case, the advantages of active inductors with adjustable inductance are obvious. The term "content" refers to the ratio of the amplitude of each harmonic to the amplitude of the fundamental frequency.

[0186] Operating Condition 3:

[0187] The parameters are shown in Table 3. Case I When t = 1.5s, a capacitor bank with a capacitance of 100μF is connected to the AC side. For example... Figure 7 As shown, the voltage fluctuation is 51.2V when using a passive inductor and 29.4V when using an active variable inductor. The capacitor on the DC side of the active inductor acts as a buffer, such as... Figure 8 As shown. Increasing the inductance value simultaneously strengthens the suppression of instantaneous charging current, reducing the impact on the DC-side filter capacitor.

[0188] Operating Condition 4:

[0189] exist Case I and Case II The load power switches between 5 kW and 7.5 kW. When a sudden change in load power is detected, the inductance value of the active variable inductor is reduced. Simulation results are as follows. Figure 9 and Figure 10 As shown, when t=1s, the power increases, and the voltage drop is 243.3 V when using passive inductor filtering, and 14.5 V overshoot and 87.4 V drop when using active variable inductor filtering. When t=2s, the power decreases, and the voltage overshoot is 411.8 V when using passive inductor filtering, and 216.6 V overshoot when using active variable inductor filtering. During this process, reducing the inductance of the active variable inductor can effectively suppress voltage overshoot and drop.

[0190] Operating Condition 5:

[0191] When the load power increases from 5 kW to 18 kW, an overload is detected. The negative inductor switches to a 10 mH positive inductor, which is connected in parallel with the 16.9 mH positive inductor, thus achieving current shunting. The simulation waveform is as follows. Figure 11 , Figure 12 and Figure 13 As shown, when the load power is 5 kW, the current in the passive inductor is 9.7 A. When t=1.5s, the load power increases to 18 kW. If a passive inductor filter is used, the inductor current suddenly becomes 35.4 A. Using an active variable inductor, the positive inductor current is 13.3 A and the negative inductor current is 22.1 A, both of which are less than the inductor current when using a passive inductor filter.

[0192] Operating Condition 6:

[0193] At t=1.5s, the load power decreases from 5 kW to 0.5 kW, as follows: Figure 14 As shown, when using a passive inductor for filtering, the current is discontinuous. When using an active variable inductor, the discontinuous current is detected, and the inductance is increased to achieve current freewheeling.

[0194] Operating Condition 7:

[0195] When t = 1.5 s, the drive signal for switch V1 is lost, and it remains in the off state. The negative inductor fault is as follows: Figure 17 As shown, the DC-side power supply capacitor voltage is unstable and cannot be controlled near the target voltage value. Figure 16 As shown, the current ripple in the active variable inductor surges from 1.09 A to 6.5 A, as... Figure 15 As shown. At t=2 s, the negative inductor is disconnected, and the positive inductor operates alone for filtering. The entire system can operate at the lowest power quality standard with a current ripple of 1.98 A.

[0196] The simulation results demonstrate that the ASD complex operating condition management method based on parallel positive and negative inductors can adjust the inductance value of the active variable inductor for complex operating conditions, thereby achieving the goals of improving filtering performance, extending capacitor life, suppressing DC-side voltage fluctuations of the converter, improving the reliability of the filtering circuit, and increasing ASD power density.

[0197] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for managing complex operating conditions using an Active Variable Inductor (ASD) based on a high-power active adjustable inductor, characterized in that: The ASD includes a drive motor. A three-phase inverter, a three-phase uncontrolled rectifier, and an active variable inductor are installed between the drive motor and the three-phase power grid. The input terminal of the three-phase uncontrolled rectifier is connected to the three-phase power grid and is used to convert the AC signal from the three-phase power grid into a DC signal. The three-phase inverter is used to convert the DC signal back into an AC signal and output it to the drive motor. The active variable inductor includes a positive inductor, a negative inductor, and a DC power supply capacitor. The DC power supply capacitor is connected in parallel to the DC side of the negative inductor. The negative inductor includes a single-phase inverter and a filter inductor. The single-phase inverter and the filter inductor are connected in series to effectively form a negative inductor, which is used to adjust the overall inductance value of the parallel positive and negative inductors by adjusting the equivalent inductance value of the negative inductor. The ASD complex operating condition management method includes: Identify the current operating status of ASD, which includes three-phase voltage imbalance, capacitor switching, load switching, overload operation, low load operation, negative inductor fault, and normal operation where the drive motor operates within a preset operating speed range. Based on the identified operating conditions, the equivalent inductance value of the negative inductor is adjusted, where: When the identified operating condition is normal operating condition or three-phase voltage imbalance condition, the equivalent inductance value of the negative inductor is adjusted so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range. When the identified operating condition is capacitor switching or load switching, the inductance value of the active variable inductor is adjusted so that the DC side voltage of the three-phase uncontrolled rectifier in the ASD is within the preset voltage range. When the identified operating condition is an overload operation, the equivalent negative inductance characteristic of the single-phase inverter is adjusted to a positive inductance characteristic until the fuse or current limiting element in the ASD trips and disconnects the load. When the identified operating condition is low load operation, adjust the equivalent inductance value of the negative inductor to make the current of the active variable inductor non-zero. When the identified operating condition is a negative inductor fault condition, the negative inductor is disconnected, and the positive inductor alone performs filtering.

2. The ASD complex operating condition management method according to claim 1, characterized in that, Methods for identifying the current operating state of ASD include: The electrical signals of multiple detection points of the ASD are collected under different operating conditions during the test. The electrical signals include the phase voltage and current of each phase on the three-phase power grid side, as well as the current of the active variable inductor, the current of the negative inductor, the DC side capacitor voltage of the negative inductor, and the current of the filter capacitor in the filter circuit. Using the electrical signal at the detection point as input and the corresponding operating conditions as output, an analytical model for predicting the operating state of ASD is established based on a neural network model. The electrical signals of each detection point are collected in real time during the operation of the ASD. Based on the electrical signals collected during operation, the analysis model is used to identify the current operating status of the ASD.

3. The ASD complex operating condition management method according to claim 1, characterized in that, When the identified operating condition is a three-phase voltage imbalance condition, the overall inductance is increased by reducing the negative inductance value, so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range. When the identified operating condition is capacitor switching, the overall inductance is increased by reducing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in ASD is within the preset voltage range. When the identified operating condition is low load operation, the overall inductance is increased by reducing the negative inductance value, so that the current of the active variable inductor is not zero. When the identified operating condition is load switching, the overall inductance is reduced by increasing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in ASD is within the preset voltage range.

4. The ASD complex operating condition management method according to claim 1, characterized in that, The single-phase inverter includes four switching transistors, namely the first switching transistor. Second switching transistor Third switching transistor Fourth switching transistor All four switching transistors are insulated-gate bipolar transistors, wherein: The gates of the four switching transistors are connected to the gate drive control signal. Power diodes are connected in parallel across the two ends of each of the four switching transistors. The collector of each switching transistor is connected to the negative terminal of the diode, and the emitter of each switching transistor is connected to the positive terminal of the diode. First switching transistor and the third switching transistor Series connection, and the first switch transistor The emitter is connected to the third switching transistor. The collector; the second switching transistor and the fourth switching transistor Series connection, and the second switch The emitter is connected to the fourth switching transistor. The collector; the first switching transistor The collector is connected to the second switching transistor. The collector of the third switching transistor The emitter is connected to the fourth switching transistor. The emitter; DC power supply capacitor Both ends are connected to the first switching transistor. collector and third switching transistor The emitter, the second switching transistor The collector is connected to the DC power supply capacitor. The positive terminal, the fourth switching transistor The emitter is connected to the DC power supply capacitor. The negative electrode; The positive inductor The two ports are respectively ports and Port, filter inductor One end is connected to the first switching transistor The emitter of one end is connected to the positive inductor as a port of the negative inductor. The ports are connected, the Port and fourth switch The collectors are connected.

5. An ASD complex operating condition management system based on a high-power active adjustable inductor, used to implement the ASD complex operating condition management method according to claim 1, characterized in that, The ASD includes a drive motor. A three-phase inverter, a three-phase uncontrolled rectifier, and an active variable inductor are installed between the drive motor and the three-phase power grid. The input terminal of the three-phase uncontrolled rectifier is connected to the three-phase power grid and is used to convert the AC signal from the three-phase power grid into a DC signal. The three-phase inverter is used to convert the DC signal back into an AC signal and output it to the drive motor. The active variable inductor includes a positive inductor, a negative inductor, and a DC power supply capacitor. The DC power supply capacitor is connected in parallel to the DC side of the negative inductor. The negative inductor includes a single-phase inverter and a filter inductor. The single-phase inverter and the filter inductor are connected in series to effectively form a negative inductor, which is used to adjust the overall inductance value of the parallel positive and negative inductors by adjusting the equivalent inductance value of the negative inductor. The ASD complex operating condition management system includes: The operating condition identification module is used to identify the current operating condition of the ASD. The operating condition includes three-phase voltage imbalance, capacitor switching, load switching, overload operation, low load operation, negative inductor fault, and normal operation when the drive motor is running within a preset operating speed range. The equivalent inductance adjustment module is used to adjust the equivalent inductance of the negative inductance based on the identified operating conditions, wherein: When the identified operating condition is normal operating condition or three-phase voltage imbalance condition, the equivalent inductance value of the negative inductor is adjusted so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range. When the identified operating condition is capacitor switching or load switching, the inductance value of the active variable inductor is adjusted so that the DC side voltage of the three-phase uncontrolled rectifier in the ASD is within the preset voltage range. When the identified operating condition is an overload operation, the equivalent negative inductance characteristic of the single-phase inverter is adjusted to a positive inductance characteristic until the fuse or current limiting element in the ASD trips and disconnects the load. When the identified operating condition is low load operation, adjust the equivalent inductance value of the negative inductor to make the current of the active variable inductor non-zero. When the identified operating condition is a negative inductor fault condition, the negative inductor is disconnected, and the positive inductor alone performs filtering.

6. The ASD complex working condition management system according to claim 5, characterized in that, The operating condition identification module includes: The data acquisition unit is used to acquire electrical signals from multiple detection points of the ASD under different operating conditions during the test. The electrical signals include the phase voltage and current of each phase on the three-phase power grid side, as well as the current of the active variable inductor, the current of the negative inductor, the DC-side capacitor voltage of the negative inductor, and the current of the filter capacitor in the filter circuit. The prediction model building unit is used to build an analysis model based on a neural network model to predict the working state of ASD, with the electrical signal of the detection point as input and the corresponding working condition as output. The predictive analysis unit is used to identify the current operating condition of the ASD based on the electrical signals of each detection point collected in real time during the operation of the ASD using the analysis model.

7. The ASD complex working condition management system according to claim 5, characterized in that, In the equivalent perception value adjustment module: When the identified operating condition is a three-phase voltage imbalance condition, the overall inductance is increased by reducing the negative inductance value, so that the first difference between the current ripple of the active variable inductor and the preset current ripple reference value is within the preset first deviation range. When the identified operating condition is capacitor switching, the overall inductance is increased by reducing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in ASD is within the preset voltage range. When the identified operating condition is low load operation, the overall inductance is increased by reducing the negative inductance value, so that the current of the active variable inductor is not zero. When the identified operating condition is load switching, the overall inductance is reduced by increasing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in ASD is within the preset voltage range.

8. The ASD complex working condition management system according to claim 5, characterized in that, The single-phase inverter includes four switching transistors, namely the first switching transistor. Second switching transistor Third switching transistor Fourth switching transistor All four switching transistors are insulated-gate bipolar transistors, wherein: The gates of the four switching transistors are connected to the gate drive control signal. Power diodes are connected in parallel across the two ends of each of the four switching transistors. The collector of each switching transistor is connected to the negative terminal of the diode, and the emitter of each switching transistor is connected to the positive terminal of the diode. First switching transistor and the third switching transistor Series connection, and the first switch transistor The emitter is connected to the third switching transistor. The collector; the second switching transistor and the fourth switching transistor Series connection, and the second switch The emitter is connected to the fourth switching transistor. The collector; the first switching transistor The collector is connected to the second switching transistor. The collector of the third switching transistor The emitter is connected to the fourth switching transistor. The emitter; DC power supply capacitor Both ends are connected to the first switching transistor. collector and third switching transistor The emitter, the second switching transistor The collector is connected to the DC power supply capacitor. The positive terminal, the fourth switching transistor The emitter is connected to the DC power supply capacitor. The negative electrode; The positive inductor The two ports are respectively ports and Port, filter inductor One end is connected to the first switching transistor The emitter of one end is connected to the positive inductor as a port of the negative inductor. The ports are connected, the Port and fourth switch The collectors are connected.

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