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

Abstract

The invention relates to the field of power electronic converter control, discloses an ASD complex working condition management method and system based on a high-power active adjustable inductor, and aims to solve the problems of poor dynamic performance and short device service life caused by fixed passive filtering parameters of the ASD under the complex working conditions of three-phase imbalance, load switching, underload, overload and the like. According to the embodiment, an active variable inductor in which a positive inductor (such as a traditional physical inductor) and a negative inductor (equivalent to a single-phase inverter) are connected in parallel is adopted; the working condition state of the ASD at the current moment is recognized, then the negative inductance value is adjusted in a targeted mode, different working conditions are adapted, and the optimal filtering effect is achieved. The management method provided by the embodiment of the invention can flexibly deal with complex working conditions, improve the filtering performance, inhibit the DC side voltage fluctuation, prolong the service life of the capacitor, and improve the ASD power density and the operation reliability at the same time.

Description

A method and system for managing complex operating conditions using ASD based on high-power active adjustable inductors. 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 Active Variable Inductor (ASD) based on a high-power active variable inductor is disclosed. The ASD includes a drive motor, and 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. The capacitor, wherein 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, wherein 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: identifying the current operating condition state of the ASD, wherein the operating condition state includes three-phase voltage imbalance operating condition, capacitor switching operating condition, load switching operating condition, overload operating condition, and low load operating condition. The system identifies three operating conditions: normal operating condition, negative inductor fault condition, and normal operating condition where the drive motor operates within a preset operating speed range. Based on the identified operating condition, the equivalent inductance value of the negative inductor is adjusted. Specifically: 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 a preset first deviation range; when the identified operating condition is capacitor switching condition or load switching condition, the equivalent inductance value of the active variable inductor is adjusted... The inductance value of the variable inductor is adjusted to keep the DC side voltage of the three-phase uncontrolled rectifier in the ASD within a preset voltage range. When the identified operating condition is 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, the equivalent inductance value of the negative inductor is adjusted to ensure that the current of the active variable inductor is not zero. When the identified operating condition is negative inductor fault operation, the negative inductor is disconnected, and the positive inductor alone performs filtering.

[0012] Furthermore, the method for identifying the current operating state of the ASD includes: collecting 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; using the electrical signals of the detection points as input and the corresponding operating conditions as output, establishing an analysis model based on a neural network model to predict the operating state of the ASD; collecting the electrical signals of each detection point when the ASD is working in real time, and using the analysis model to identify the current operating state of the ASD based on the electrical signals collected during operation.

[0013] Furthermore, when the identified operating condition is a three-phase voltage imbalance condition, the overall inductance is increased by decreasing the negative inductor value, so 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; when the identified operating condition is a capacitor switching condition, the overall inductance is increased by decreasing the negative inductor value, so that the DC side voltage of the three-phase uncontrolled rectifier in the ASD is within a preset voltage range; when the identified operating condition is a low-load operation condition, the overall inductance is increased by decreasing the negative inductor value, so that the current of the active variable inductor is not zero; when the identified operating condition is a load switching condition, the overall inductance is decreased by increasing the negative inductor value, so that the DC side voltage of the three-phase uncontrolled rectifier in the ASD is within a preset voltage range.

[0014] 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 (IGBTs), wherein: the gates of the four switching transistors are connected to a 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; the 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 of 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. 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 terminal; 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 one port of the negative inductor. The ports are connected, the Port and fourth switch The collectors are connected.

[0015] 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. 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 into an AC signal and output it to the drive motor. The active variable inductor includes a positive inductor and a negative inductor. The system includes an inductor and a DC power supply capacitor, with the DC power supply capacitor connected in parallel to the DC side of the negative inductor. The negative inductor comprises 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. This 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 an operating condition identification module, used to identify the current operating condition of the ASD, including normal operation, three-phase voltage imbalance, capacitor switching, and load switching. The system includes overload operation, low load operation, negative inductor fault operation, and normal operation of the drive motor within a preset operating speed range. The equivalent inductance adjustment module adjusts the equivalent inductance value of the negative inductor based on the identified operating conditions. Specifically: when the identified operating condition is normal operation or three-phase voltage imbalance, 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 a preset first deviation range; when the identified operating condition is capacitor switching or negative... During load switching, the inductance value of the active variable inductor is adjusted to keep the DC side voltage of the three-phase uncontrolled rectifier in the ASD within the preset voltage range. When the identified operating condition is 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, the equivalent inductance value of the negative inductor is adjusted to ensure that the current of the active variable inductor is not zero. When the identified operating condition is negative inductor fault operation, the negative inductor is disconnected, and the positive inductor filters the load separately.

[0016] Furthermore, the operating condition identification module includes: a data acquisition unit, 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; a prediction model construction unit, used to take the electrical signals of the detection points as input and the corresponding operating conditions as output, and establish an analysis model based on a neural network model to predict the operating condition state of the ASD; and a prediction analysis unit, used to identify the current operating condition state of the ASD based on the analysis model according to the electrical signals of each detection point acquired in real time when the ASD is working.

[0017] Furthermore, in the equivalent inductance adjustment module: when the identified operating condition is a three-phase voltage imbalance condition, the overall inductance is increased by decreasing 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 a capacitor switching condition, the overall inductance is increased by decreasing the negative inductance value, 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 a low load operation condition, the overall inductance is increased by decreasing the negative inductance value, so that the current of the active variable inductor is not zero; when the identified operating condition is a load switching condition, the overall inductance is decreased by increasing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in the ASD is within the preset voltage range.

[0018] 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 (IGBTs), wherein: the gates of the four switching transistors are connected to a 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; the 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 of 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. 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 terminal; 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 one port of the negative inductor. The ports are connected, the Port and fourth switch The collectors are connected.

[0019] 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

[0020] Figure 1 is a schematic diagram of the application of the ASD complex operating condition management method and system; Figure 2 is a block diagram of the structure and control of an active negative inductor; Figure 3 is a diagram of the system under normal operating conditions. Figure 4 shows the DC-side capacitor voltage and inductor current under unbalanced conditions; Figure 5 shows the waveform of the passive inductor filter under unbalanced conditions; Figure 6 shows the waveform of the active variable inductor filter with positive and negative parallel connections under unbalanced conditions; Figure 7 shows the DC-side voltage of the rectifier under capacitor switching conditions; Figure 8 shows the DC-side supply capacitor voltage of the active variable inductor under capacitor switching conditions; Figure 9 shows the DC-side voltage waveform of the rectifier under load switching conditions; Figure 10 shows the current waveform of the active variable inductor under load switching conditions; Figure 11 shows the overload condition... Figure 12 shows the current waveforms of the positive and negative inductors in the active variable inductor under overload conditions; Figure 13 shows the current waveform of the positive inductor in the passive inductor and active variable inductor under overload conditions; Figure 14 shows the current waveform of the active variable inductor under low load conditions; Figure 15 shows the current of the active variable inductor under negative inductor fault conditions; Figure 16 shows the DC-side capacitor voltage of the active variable inductor under negative inductor fault conditions; Figure 17 shows the current waveforms of the positive and negative inductors in the active variable inductor under negative inductor fault conditions. Detailed Implementation

[0021] 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.

[0022] Example 1 (Referring to Figures 1 and 2) illustrates an ASD complex operating condition management method based on a high-power active adjustable inductor. 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, The system includes a negative inductor and a DC power supply capacitor, with the DC power supply capacitor connected in parallel to the DC side of the negative inductor. The negative inductor comprises 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. This 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: identifying the current operating condition of the ASD, including three-phase voltage imbalance, capacitor switching, load switching, and overload operation. The system identifies the following operating conditions: low-load operation, negative inductor fault operation, and normal operation of the drive motor within a preset operating speed range. Based on the identified operating condition, the equivalent inductance value of the negative inductor is adjusted. Specifically: when the identified operating condition is normal operation or three-phase voltage imbalance, 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 a preset first deviation range; when the identified operating condition is capacitor switching or load switching, the equivalent inductance value of the active variable inductor is adjusted... The inductance value of the variable inductor ensures that the DC-side voltage of the three-phase uncontrolled rectifier in the ASD is within a preset voltage range. When the identified operating condition is 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, the equivalent inductance value of the negative inductor is adjusted until the current of the active variable inductor is not zero. When the identified operating condition is negative inductor fault operation, the negative inductor is disconnected, and the positive inductor alone performs filtering.

[0023] 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.

[0024] As shown in Figure 1, in some other embodiments, the method for identifying the current operating state of the ASD includes: collecting electrical signals from multiple detection points of the ASD under different operating conditions during testing; the electrical signals include the phase voltage and current of each phase of the three-phase power grid, 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 signals of the detection points as input and the corresponding operating conditions as output, establishing an analysis model based on a neural network model to predict the operating state of the ASD; collecting the electrical signals of each detection point when the ASD is working in real time, and using the analysis model to identify the current operating state of the ASD based on the electrical signals collected during operation.

[0025] Example 2: A method for managing complex operating conditions using an Active Variable Inductor (ASD) based on a high-power active variable inductor. 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 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. 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 inverter is connected in series with the filter inductor to form an equivalent 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: Step 1, identifying the current operating condition of the ASD, which includes three-phase voltage imbalance, capacitor switching, load switching, overload operation, low load operation, negative inductor fault, and normal operation of the drive motor within a preset operating speed range. In this embodiment, taking the seven operating condition modes of ASD shown in Table 1 as an example, the identification method of the operating condition of ASD is described in detail. In Table 1, operating condition 1 is the normal operating condition; the operating condition changes caused by the grid side are mainly operating condition 2 (three-phase voltage imbalance) and operating condition 3 (capacitor switching). The operating condition changes caused by the load side are mainly operating condition 4 (load switching), operating condition 5 (overload operation), and operating condition 6 (low load operation). When considering the equivalent overall inductance of active devices, and taking into account the faults in the power electronic circuits, a relevant analysis of operating condition 7 (negative inductance fault condition) was also conducted.

[0026] Table 1 List of Operating Modes

[0027] Neural Network-Based Operating Condition Pattern Recognition: 1.1 Acquiring 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; in this embodiment, as shown in Figures 1 and 2, the grid-side voltage is synchronously acquired through 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.

[0028] 1.2 Using the electrical signal at the detection point as input and the corresponding operating conditions as output, an analysis model for predicting the operating conditions of ASD is established based on a neural network model; 1.2.1 The preprocessed voltage and current signals are aligned according to the time series, and time-domain statistical features (such as peak value, effective value, ripple coefficient) are extracted or multi-dimensional feature vectors are directly constructed to cover key electrical parameters of the grid side, load side, and filter circuit, forming the input samples of the neural network.

[0029] 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).

[0030] 1.3 Real-time acquisition of electrical signals from each detection point during ASD operation; based on the acquired electrical signals, the analysis model is used to identify the current operating condition of ASD. In this embodiment, the multi-feature vectors acquired and preprocessed in real time are input into the trained neural network, and the probability of the output operating condition category is calculated through forward propagation. The operating condition mode of the current ASD system is determined based on the maximum probability, thereby achieving rapid and accurate identification of the operating condition.

[0031] Step 2: Adjust the equivalent inductance value of the negative inductor according to the identified operating conditions. The adjustment logic for each operating condition is as follows: 2.1) When the identified operating condition is normal operation or three-phase voltage imbalance, 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; if the identified operating condition is 1—normal operation: for the 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: Based on 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] If identified as operating condition 2—three-phase voltage imbalance: When 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.

[0036] 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 ASD within the preset voltage range; if the identified condition is operating condition 3—capacitor switching: In order to compensate for reactive power, improve the power factor, reduce line losses, stabilize the system voltage, and at the same time improve the power transmission efficiency and power supply quality of the power system, the capacitor bank will be switched on.

[0037] 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.

[0038] 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.

[0039] If identified as operating condition 4—load switching condition: the DC side voltage will drop when the load current increases and will overshoot when the load current decreases. Suppressing this voltage fluctuation requires adjustment. This reduces the overall inductance, improves the current response speed, and suppresses voltage dips and overshoots.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 2.3) When the identified operating condition is overload, 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. Overload causes the inductor current to far exceed the rated value, resulting in a surge in copper losses, hysteresis, and eddy current losses, leading to inductor overheating, accelerated winding insulation aging, and even short circuits. The magnetic core is prone to saturation, the inductance value drops sharply, the filtering and harmonic suppression capabilities fail, and DC-side voltage ripple intensifies. At the same time, the strong electromagnetic force generated by the large current causes winding vibration and core loosening, shortening the inductor life and potentially causing the LC circuit resonant frequency to shift and the amplifier circuit to experience disturbances.

[0044] 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.

[0045] 2.4) When the identified operating condition is low load, increase the overall inductance value of the active variable inductor until the current of the active variable inductor is not zero. 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, and it cannot maintain continuous power supply. This phenomenon will aggravate filter losses and deteriorate the stability of load power supply. It is necessary to increase the inductance value of the active variable inductor to suppress discontinuity.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 2.5) When the identified operating condition is a negative inductor fault condition, the negative inductor is disconnected and the positive inductor alone performs filtering. The negative inductor in the active variable inductor is obtained through the equivalent of a single-phase inverter. Considering that common faults of single-phase inverters include: power device breakdown and damage, abnormal drive module and controller, unbalanced inverter bridge, malfunction of protection circuit, and failure of heat dissipation system, the operating stability of LC filter circuit will be affected.

[0050] 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.

[0051] Figure 1 shows a schematic diagram of the application of the high-power active variable inductor in an adjustable speed drive in this embodiment: The adjustable speed drive (ASD) includes an economical three-phase diode bridge rectifier, a DC link filter, and a three-phase inverter; the passive inductor is 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.

[0052] 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; 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; 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. Resulting in pressure drop Combined with negative inductance Sensitivity and voltage drop This yields control signals for the four switching transistors.

[0053] 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 (IGBTs), wherein: the gates of the four switching transistors are connected to a 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; the 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 of 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. 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 terminal; 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 one port of the negative inductor. The ports are connected, the Port and fourth switch The collectors are connected.

[0054] 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.

[0055] 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.

[0056] 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 the suppression effect on current ripple. The specific control method is as follows: Step 1: Real-time acquisition of the DC side voltage of the negative inductor. Negative inductor port voltage and negative inductor current Analysis to obtain DC side voltage Step 2: Based on the second difference, adjust the virtual resistance of the negative inductor using a PI controller 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; in this embodiment, the target value of the virtual resistance of the negative inductor adjusted by the PI controller is... ,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.

[0057] 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 a preset first deviation range; in this embodiment, the inductance value of the positive inductor is set 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 control equivalent sensing value 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. .

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] During the adjustment process, based on the initial value set by the negative inductance value, and combined with the adjustment direction and rate, the control parameters are updated in real time using the disturbance observation method. The specific adjustment process is as follows: Step 3.1: Based on the virtual resistance adjusted by the PI controller... and negative inductance Port voltage Current Analysis yields negative inductance The voltage drop of the actual equivalent inductance In this embodiment, the negative inductor The voltage drop of the actual equivalent inductance is based on The results were obtained through analysis.

[0063] 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; 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.

[0064] 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 inductance value; 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. .

[0065] 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:

[0066] in

[0067] It is the order of the Lagrange extrapolation method. For the summation index, , where k is the 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.

[0068] 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.

[0069] 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: .

[0070] Table 2 Effective Switching Status of Bridge H

[0071] The prediction model for the output current of a single-phase inverter is established as follows:

[0072] 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. .

[0073] Finally, define the cost function. And select the optimal switching state.

[0074] Based on the cost function, determine the optimal switching state for the next instant.

[0075] To verify the feasibility of the management method in this embodiment, a simulation module was built in PSIM according to Figures 1 and 2, and predetermined control parameters were set according to Table 3. The simulation was then started. Table 3: Simulation Experiment Parameter Table

[0076] Simulation analysis yielded the following results for each operating condition: Operating Condition 1: In the adjustable speed driver, an active variable filter replaced the passive inductor. The experimental parameters are shown in Case I of Table 3. The target current ripple (i.e., the current ripple reference value) was set to 0.5A, with a first deviation range of ±6%. Simulation results showed that the current in the active variable inductor... As shown in Figure 3, 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%.

[0077] Operating Condition 2: The target current ripple is 1A. A passive inductor with a capacitance of 33.7mH and an active inductor are compared in an experiment. The parameters are shown in Case I of Table 3. When t=5s, a three-phase voltage imbalance of 5% occurs. The filtering effect of the passive inductor is shown in Figure 4. The current ripple increases from 0.96 A to 2.16 A.

[0078] When a voltage imbalance occurs, the current ripple is detected to be higher than the target value. By increasing the inductance of the active inductor, the current ripple is suppressed to the target current ripple. As shown in Figure 5, the current ripple before and after the three-phase imbalance occurs is 1.03 A and 1.15 A, respectively.

[0079] As shown in Figure 6, 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.

[0080] Operating Condition 3: Parameters are shown in Case I of Table 3. At t=1.5s, a 100μF capacitor bank is connected to the AC side. As shown in Figure 7, when using a passive inductor, the voltage fluctuation is 51.2V; when using an active variable inductor, the voltage fluctuation is 29.4V. The DC-side capacitor in the active inductor acts as a buffer, as shown in Figure 8. Increasing the inductance value further strengthens the suppression of instantaneous charging current, reducing the impact on the DC-side filter capacitor.

[0081] Operating Condition 4: Switching between Case I and Case II, with load power switching between 5 kW and 7.5 kW. When a sudden change in load power is detected, the inductance of the active variable inductor is reduced. Simulation results are shown in Figures 9 and 10. At t=1s, the power increases, and the voltage drop is 243.3 V with passive inductor filtering, and 14.5 V overshoot and 87.4 V drop with active variable inductor filtering. At t=2s, the power decreases, and 411.8 V overshoot is 216.6 V with active variable inductor filtering. During this process, reducing the inductance of the active variable inductor effectively suppresses voltage overshoot and drop.

[0082] Operating Condition 5: The load power increases from 5 kW to 18 kW, overload is detected, and the negative inductor switches to a 10 mH positive inductor, which is connected in parallel with the 16.9 mH positive inductor to achieve current shunting. The simulation waveforms are shown in Figures 11, 12, and 13. 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 passive inductor filtering 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 current in the negative inductor is 22.1 A, both of which are less than the inductor current when using passive inductor filtering.

[0083] Operating Condition 6: At t=1.5s, the load power decreases from 5 kW to 0.5 kW, as shown in Figure 14. When using a passive inductor filter, the current is discontinuous. When using an active variable inductor, the discontinuous current is detected, and the inductance is increased to achieve freewheeling.

[0084] Condition 7: At t=1.5 s, the drive signal for switch V1 is lost, and it remains in the off state. The negative inductor fault is shown in Figure 17. The DC-side power supply capacitor voltage becomes unstable and cannot be controlled near the target voltage value, as shown in Figure 16. The current ripple in the active variable inductor surges from 1.09 A to 6.5 A, as shown in Figure 15. 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.

[0085] 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.

[0086] 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 scope of protection 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: identifying the current operating condition of the ASD, including three-phase voltage imbalance, capacitor switching, load switching, overload operation, low load operation, negative inductor fault, and normal operation of the drive motor within a preset operating speed range; adjusting the equivalent inductance value of the negative inductor according to the identified operating condition, wherein: when the identified operating condition is normal operation or three-phase voltage imbalance, 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 a preset range. Within the first deviation range; 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; when the identified operating condition is overload operation, adjust the equivalent negative inductance characteristic of the single-phase inverter 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 negative inductor fault operation, disconnect the negative inductor and let the positive inductor alone perform filtering.

2. The ASD complex operating condition management method according to claim 1, characterized in that, The method for identifying the current operating state of the ASD includes: collecting electrical signals from multiple detection points of the ASD under different operating conditions during testing; 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 signals of the detection points as input and the corresponding operating conditions as output, establishing an analysis model based on a neural network model to predict the operating state of the ASD; collecting the electrical signals of each detection point when the ASD is working in real time, and using the analysis model to identify the current operating state of the ASD based on the electrical signals collected during operation.

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 decreasing 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 a capacitor switching condition, the overall inductance is increased by decreasing the negative inductance value, 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 a low load operation condition, the overall inductance is increased by decreasing the negative inductance value, so that the current of the active variable inductor is not zero; when the identified operating condition is a load switching condition, the overall inductance is decreased by increasing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in the 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 (IGBTs), wherein: the gates of the four switching transistors are connected to a 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; the 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 of 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. 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 terminal; 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 one 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: an operating condition identification module, used to identify the current operating condition state of the ASD, including 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; and an equivalent inductance value adjustment module, used to adjust the equivalent inductance value of the negative inductor according to the identified operating condition state, wherein: when the identified operating condition state is normal operation or three-phase voltage imbalance, the equivalent inductance value of the negative inductor is adjusted so that the current ripple of the active variable inductor is close to a preset current ripple reference value. The first difference between them 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 overload operation, the equivalent negative inductance characteristic of the single-phase inverter is adjusted to 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, the equivalent inductance value of the negative inductor is adjusted so that the current of the active variable inductor is not zero; when the identified operating condition is negative inductor fault operation, 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: a data acquisition unit, 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; a prediction model construction unit, used to take the electrical signals of the detection points as input and the corresponding operating conditions as output, and establish an analysis model based on a neural network model to predict the operating condition of the ASD; and a prediction analysis unit, used to identify the current operating condition of the ASD based on the analysis model according to the electrical signals of each detection point acquired in real time when the ASD is working.

7. The ASD complex working condition management system according to claim 5, characterized in that, In the equivalent inductance adjustment module: when the identified operating condition is three-phase voltage imbalance, the overall inductance is increased by decreasing 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 decreasing the negative inductance value, 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 low load operation, the overall inductance is increased by decreasing 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 decreased by increasing the negative inductance value, so that the DC side voltage of the three-phase uncontrolled rectifier in the 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 (IGBTs), wherein: the gates of the four switching transistors are connected to a 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; the 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 of 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. 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 terminal; 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 one port of the negative inductor. The ports are connected, the Port and fourth switch The collectors are connected.

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