349 results about "Three level inverter" patented technology

The invention discloses a hybrid modulation strategy for neutral-point voltage balance control and common-mode voltage suppression of a three-level inverter, and belongs to the technical field of power electronics. In order to solve the problems that the neutral-point voltage of a three-level inverter is unbalanced and the common-mode voltage is large under traditional modulation, the invention provides a novel modulation strategy formed by mixing virtual space vector modulation and intermittent modulation, and according to virtual space vector modulation, space vectors with small common-mode voltage are selected to construct virtual small vectors and middle vectors; adjusting the midpoint current through the midpoint voltage control parameter; dPWMA capable of suppressing common-mode voltage is selected for intermittent modulation. According to the hybrid modulation strategy, common-mode voltage suppression can be kept, when the neutral-point voltage is balanced, DPWMA is selected to reduce switching loss, and when the neutral-point voltage is unbalanced, a modulation method which is more effective for recovering balance of the neutral-point voltage is selected to achieve the purpose of faster realization of neutral-point voltage balance.

The invention discloses a method for diagnosing an IGBT open-circuit fault and a current sensor fault of a T-type three-level inverter, belongs to the technical field of inverter fault diagnosis, and is used for solving the problems of diagnosis and positioning when a three-level T-type inverter IGBT switch tube and a sensor have faults. Comprising the following steps: classifying and marking and numbering fault types of an open-circuit fault of a T-type three-level inverter IGBT and a fault of a current sensor; fault samples are collected and divided into a training set and a test set according to the proportion of 7: 3; a TCN-LSTM-SelfAction fault diagnosis model is constructed, and model training is carried out by using the training set; the trained model is used for evaluating the accuracy of fault type diagnosis of the training set and the test set. According to the diagnosis method, the fault types and the fault positions of the IGBT open-circuit fault and the current sensor fault can be diagnosed at the same time, the TCN and the LSTM are selected to be combined, local information and global relation of fault features can be captured at the same time, and meanwhile, the performance of a model is improved by combining a self-attention mechanism in the LSTM, and the accuracy is improved.

The invention discloses a three-level inverter dual-tracking model prediction control method and an inverter, and the method comprises the steps: constructing an integral sliding mode observer, and obtaining a current prediction value and a lumped disturbance estimation value through the integral sliding mode observer; calculating a voltage error of the inverter, and substituting the voltage error into the PI controller to obtain a voltage tracking control item; based on the voltage tracking control term, a switching state that minimizes the cost function is selected to control the inverter. The integral sliding mode observer is configured to calculate a current prediction error between a current prediction value of a current control period and a system output current, introduce an integrator to track the current prediction error, and generate an error function based on an output result of the integrator and the current prediction error. And feeding back a current predicted value and a lumped disturbance estimated value of the next control period through an error function. According to the invention, the method can achieve the quick estimation of the operation state of the inverter and the robust compensation of disturbance, reduces the steady-state tracking error, and reduces the total harmonic distortion of the inverter.

The invention relates to the technical field of inverter pulse width modulation, in particular to a neutral-point potential balance and low common-mode voltage modulation method and system based on an SVPWM inverter, and the method comprises the steps: determining a basic voltage vector based on different switching states of an NPC three-level inverter; respectively determining the midpoint current of each fundamental voltage vector, and determining the fundamental voltage vector causing midpoint potential deviation; combining with a large vector and a zero vector, and performing mode division of a single vector space region; determining an expected current according to the DC side capacitor voltage of the inverter, and constructing a target function based on the expected current; and performing region judgment according to the output synthesized voltage vector, determining a corresponding optimal division mode, obtaining each basic voltage vector of the synthesized voltage vector and a corresponding duty ratio, and determining a switching sequence to obtain a PWM wave. While the neutral-point potential balance and common-mode voltage suppression of the NPC three-level inverter are realized, the switching frequency of the inverter is effectively reduced, and the switching loss is reduced.

The invention discloses a modulation method of a three-level inverter, electronic equipment and a storage medium, and the modulation method comprises the steps: calculating a voltage difference value between the voltage at the two ends of a lower capacitor and the voltage at the two ends of an upper capacitor; respectively calculating the product of the voltage difference value and each phase current to obtain a plurality of midpoint balance judgment components, and determining a midpoint voltage compensation component according to the symbols of all the midpoint balance judgment components; performing proportional equalization processing on the neutral-point voltage compensation component to obtain a neutral-point voltage balance component; and superposing the neutral-point voltage balance component and the obtained zero-sequence voltage compensation component to an original modulation signal of the three-level inverter to obtain a target modulation signal. In the invention, a proportion control link is added for the loop injected with the common-mode component, so that a space can be created for injecting the zero-sequence component for the direct-current bus, the balance of the neutral-point voltage and the suppression of the zero-sequence circulating current are realized, the circulating current consumption is effectively reduced, and the electric energy quality and the transmission efficiency are improved.

The present invention provides a method for cooperatively suppressing a common-mode voltage and current harmonics of coupled three-level inverters, comprising: based on amplitude and phase angle of reference voltage vector, determining sector and region in which the reference voltage vector is located; selecting four basic voltage vectors with low common-mode voltage amplitudes to synthesize the reference voltage vector; writing volt-second balance equation based on selected basic voltage vectors, and calculating duty cycles thereof; and based on sector and region in which reference voltage vector is located, set value of voltage difference across capacitors on direct current side, and actual value of voltage difference across capacitors on direct current side, (1) updating duty cycles of basic voltage vectors, to realize separate control of capacitor voltage; and (2) designing and converting switching sequence into PWM drive signal of power switch, to control the coupled three-level inverter to operate.

The invention relates to the technical field of open-winding dual-inverter open-circuit faults, and provides a common-mode voltage-based open-winding dual three-level inverter open-circuit fault diagnosis method, which comprises the following steps of: constructing an MLD common-mode voltage model of a dual three-level inverter according to a switching function; obtaining a fault characteristic quantity according to an MLD common-mode voltage model of the dual three-level inverter; judging an initial phase of the fault characteristic quantity, and identifying a fault bridge arm pair according to the initial phase of the fault characteristic quantity; obtaining a fault characteristic value according to the fault bridge arm pair and the fault characteristic quantity; and judging a fault type according to the fault characteristic value and a threshold value. According to the invention, the difference between the ideal common-mode voltage and the actual common-mode voltage is used as the characteristic value to detect the fault, and the specific fault switch tube is positioned according to the specific phase, amplitude and positive and negative of the characteristic value, so that the fault diagnosis and positioning of the specific switch tube can be completed only by detecting the common-mode voltage.

The invention discloses a multi-target robust model predictive control method for a permanent magnet synchronous motor, which is used for a three-level inverter power supply permanent magnet synchronous motor system with a quadruple BOOST booster circuit, and comprises the following steps: firstly, carrying out system modeling and discretization, then carrying out multi-target cost function design, solving a multi-target optimization problem based on compromise programming and a fuzzy decision method, and finally, carrying out multi-target robust model predictive control on a three-level inverter power supply permanent magnet synchronous motor system with a quadruple BOOST booster circuit. And calculating a delay compensation strategy and a robustness enhancement measure, and finally calculating the output voltage of the quadruple Boost circuit and the output voltage of the inverter. The method improves the DC bus voltage, improves the output power and efficiency, enhances the robustness of the system to parameter change and uncertainty, realizes multi-target optimization control, ensures that the system stably and efficiently operates under complex working conditions, and is suitable for the fields of speed regulation of motors with booster circuits and the like.

The invention discloses a modulation method and system for suppressing common-mode voltage and midpoint low-frequency oscillation of a three-level inverter, and the method comprises the steps: obtaining a reference voltage vector, and judging a sector where the reference voltage vector is located according to the division condition of a space sector; according to the space sector division condition and the position of the reference voltage vector, a synthetic virtual vector and a corresponding basic voltage vector are obtained, and the action sequence of the basic voltage vector is determined; based on the action sequence of the basic voltage vector, virtual vector action time is calculated according to volt-second balance, the virtual vector action time is distributed to the basic voltage vector action time, and a pulse width modulation signal is output to control the on-off of a power device of the inverter, so that the common-mode voltage of the three-level inverter is suppressed, and the three-level inverter is obtained. And safe and stable operation of the system is guaranteed.

A multi-level inverter control system includes a power storage system with a high-voltage input, a low-voltage input, and an intermediate-voltage input. The intermediate-voltage input is at a voltage between the high-voltage and low-voltage inputs. A multi-level inverter contains several switches, a high-voltage input connected to the high-voltage input, a low-voltage input connected to the low-voltage input, and an intermediate-voltage input connected to the intermediate-voltage input. A controller is coupled to the multi-level inverter and contains at least one processor and memory.The memory stores instructions configured to cause the controller to operate the multi-level inverter in a three-level inverter mode, a full-power two-level inverter mode, a first partial-power two-level inverter mode, and a second partial-power two-level inverter mode.

The invention discloses a current harmonic suppression method, device and equipment of a T-type three-phase three-level inverter and a readable storage medium, and relates to the technical field of power electronics. Comprising the steps of obtaining an upper capacitor voltage and a lower capacitor voltage of the T-type three-phase three-level inverter, and determining a target control set according to a relation between the upper capacitor voltage and the lower capacitor voltage; for each candidate vector voltage in the target control set, calculating a cost value corresponding to each candidate vector voltage; and taking the candidate vector voltage corresponding to the minimum cost value as a target vector voltage. According to the method provided by the invention, the effective suppression of the current harmonics of the T-type three-phase three-level inverter is realized.

The invention discloses a control method, device, equipment and product of a dual three-level inverter, and the method comprises the steps: obtaining a zero-sequence current and a neutral-point potential in the dual three-level inverter when the dual three-level inverter operates; traversing all selectable clamping combinations, and calculating the zero-sequence voltage of the dual three-level inverter and the neutral-point current of the dual three-level inverter which are correspondingly generated; and selecting the corresponding clamping combination when the positive and negative directions of the zero-sequence voltage and the zero-sequence current are opposite and the positive and negative directions of the midpoint current and the midpoint potential are opposite as the clamping combination selected by the first three-level inverter and the second three-level inverter. According to the dual three-level inverter, the appropriate clamping combination of the first three-level inverter and the second three-level inverter can be selected, zero-sequence current suppression and neutral-point potential balance in the dual three-level inverter are achieved, the output performance of the dual three-level inverter is improved, meanwhile, the switching action frequency of the dual three-level inverter can be reduced, and therefore switching loss is reduced.

The invention provides a phase delay error suppression method for a midpoint current sensor of a T-type three-level inverter, and the method comprises the steps: determining a sector and a sub-region where a target voltage vector is located according to the input target voltage vector, selecting a basic voltage vector for synthesis according to the sub-region where the target voltage vector is located, calculating the action time of the voltage vector, and calculating the phase delay error of the midpoint current sensor of the T-type three-level inverter. The switching time of the seven-segment switch is determined, so that a seven-segment PWM switching signal is generated; judging whether the target voltage vector is located in an unobservable area according to the action time of the basic voltage vector; if yes, maintaining the original seven-segment PWM switching signal to send waves; otherwise, adjusting the seven-segment PWM switching signal, and compensating the observable voltage vector which does not meet the minimum sampling time by shifting the PWM signal to obtain a plurality of stable current sampling windows; and phase delay error compensation of the reconstructed three-phase current is realized according to the relationship between the sampling currents. According to the method, the distortion of the reconstruction current is improved, so that the precision of the three-phase reconstruction current is effectively improved.

The invention discloses a cooperative control method for neutral-point balance and circulation suppression of an inverter. The method comprises the following control steps: collecting three-phase current of a power grid side, and generating a three-phase bridge arm modulation signal through a grid-connected current control loop; collecting a lower half bus voltage and generating a first zero-sequence component through a neutral-point balance control loop; collecting three-phase current on the power grid side, and generating a second zero-sequence component through a circulating current suppression control loop; inputting the first zero-sequence component and the second zero-sequence component into a competition logic processing module, and generating a final zero-sequence component by using a competition mechanism based on dynamic weight distribution; and the final zero-sequence component is subjected to over-modulation processing and then superposed to a three-phase bridge arm modulation signal of a grid-connected current control loop, and then a control signal of the three-level inverter is obtained after PWM (Pulse-Width Modulation). The method has the advantages that by dynamically coordinating the midpoint balance and circulating current restraining requirements, efficient coordination of the midpoint balance and the circulating current restraining requirements can be achieved, the control complexity is reduced, and the method is suitable for low-cost industrial application scenes.

The invention discloses a new energy grid-connected three-level inverter midpoint potential balance modulation method and system, and the method comprises the steps: carrying out the sector judgment and reference voltage vector mapping of three-phase reference voltages va, vb and vc from a controller; calculating an optimal switching waveform and time parameters da1, db1 and dc1 thereof according to the mapped three-phase reference voltages va1, vb1 and vc1, the sampled midpoint potential deviation V1-V2 and the three-phase current iabc, and reflecting the time parameters da1, db1 and dc1 into time parameters da, db and dc of each phase waveform of an original voltage sector; and inputting the time parameters da, db and dc of each phase waveform of the original voltage sector into a modulator to generate a modulation signal so as to control the three-level inverter. The invention aims at suppressing the neutral-point potential fluctuation of the new energy grid-connected three-level inverter and reducing the current harmonic wave and the switching loss at the same time.

The invention discloses a fault diagnosis method, device and equipment for an NPC three-level inverter and a medium, and relates to the technical field of inverter fault diagnosis, and the method comprises the steps: building a fault stator current analysis model according to a fault stator current change rule of the inverter; a fault phase and a fault bridge arm are extracted and positioned by using a sliding window averaging method; and calculating and setting a fault positioning reference value under an ideal condition, and comparing the fault positioning reference value with a fault positioning actual value under an actual condition to position a faulted IGBT (Insulated Gate Bipolar Translator). A fault stator current analysis model is established to simulate a set current change condition under an ideal condition, a fault positioning reference value is calculated, and whether an actual fault condition is consistent with a set ideal fault condition is distinguished by a deviation between the fault positioning reference value and a fault positioning actual value of an actual condition, and whether a fault is an inner pipe or an outer pipe is positioned. During calculation, a current mean value from a fault moment to a first zero-crossing moment is utilized, a fault IGBT can be positioned in a fundamental wave period, and fault diagnosis and positioning can be quickly and efficiently carried out.

The invention relates to the field of three-level inverters, and particularly discloses a model-free strong-robustness predictive control method and system for a three-level SNPC inverter, and the method comprises the steps: carrying out the real-time sampling and coordinate transformation of the inverter, and obtaining the current and voltage components under a two-phase static coordinate system; establishing a hyper-local model, enabling the system parameter deviation and the external disturbance to be uniformly equivalent to lumped disturbance, and designing a full-order sliding-mode observer for real-time estimation; calculating a reference voltage vector based on the disturbance estimation value and the extrapolated reference current; and an optimal double-vector combination is selected through space vector optimization, action time is solved, redundant small vectors are selected according to midpoint voltage deviation, and PWM driving signals are generated. According to the method, excellent current tracking performance and low harmonic distortion can still be kept under the conditions of parameter mismatch and working condition change, meanwhile, neutral-point potential balance on the direct-current side is achieved, and the method has the advantages of being small in calculation amount, high in robustness, easy to achieve in engineering and the like.

The invention discloses a multi-loop anti-interference ride-through control system and method for a high-voltage three-level inverter, and is suitable for a three-phase T-type three-level grid-connected inverter. The system comprises a direct current side power supply circuit, an inversion main circuit, a filtering grid-connected circuit, a signal sampling and conditioning circuit, a multi-loop cooperative controller and a PWM driving and protecting circuit. According to the control method, a robust synchronous reference is provided through an outer ring virtual synchronous generator strategy; a middle ring adopts a virtual impedance model containing a high-frequency compensation item to selectively suppress switching noise; the inner ring adopts a quasi-proportional resonance controller to realize fundamental current zero-static-error tracking; the modulation layer dynamically optimizes a discontinuous pulse width modulation strategy based on a real-time EMI index; and the rings are switched to a low-voltage ride-through mode in cooperation when a fault occurs. On the premise of not increasing hardware, the anti-interference capability, the current quality and the ride-through stability of the inverter under the working conditions of strong electromagnetic interference and power grid drop are effectively improved.

The invention discloses a vector reconstruction harmonic suppression method for a three-level inverter power supply permanent magnet synchronous motor, and relates to the technical field of motor harmonic and noise suppression. Calculating action time of three basic vectors, selecting the three basic vectors, adjusting an original vector synthesis sequence in a single carrier period into a vector reconstruction synthesis sequence, calculating three time nodes of a fifth-segment sequence and a sixth-segment sequence according to the original vector synthesis sequence, and calculating the time nodes of the fifth-segment sequence and the sixth-segment sequence; the action duration of the two basic vectors after adjustment is calculated according to the vector reconstruction synthesis sequence, the numerical value of a switching time node of a three-level inverter switching tube is updated according to the action duration, and the assigned value of a time register is calculated and updated in a circulating mode in the operation process of the permanent magnet synchronous motor system. And generating a PWM (Pulse Width Modulation) driving signal to control a three-level inverter switching tube to drive a motor. Improvement is carried out based on a traditional SVPWM technology, the high-frequency harmonic performance of the three-level inverter and the motor driving system can be remarkably improved, system cost and operation difficulty do not need to be increased, and the method is simple and easy to implement.

The invention discloses an optimized virtual vector modulation strategy of a T-type three-level inverter, which is characterized in that a sector is re-divided based on the virtual vector modulation strategy, a synthesis mode of a virtual vector is optimized, a low-amplitude common-mode voltage vector is adopted to synthesize the virtual vector, on one hand, common-mode voltage generated by the inverter can be inhibited, and on the other hand, the common-mode voltage generated by the inverter can be inhibited; and on the other hand, the optimized modulation method does not influence the neutral point potential, the smoothness of the direct output voltage of the inverter is improved, the voltage quality is improved, and the method has the advantages of low harmonic content of the output current and the like. In addition, the method solves the problems of inverter output voltage distortion, common-mode voltage spike and the like caused by a dead zone effect through a voltage vector compensation method, and has guiding significance for improving the reliability of a photovoltaic system and a micro-grid system.

The invention relates to an equivalent two-level fast double-vector model predictive control method applied to a three-level inverter. The method specifically comprises the following steps: sampling output current and direct current side upper and lower capacitor voltages at a k moment; predicting an expected voltage according to the mathematical model of the three-level inverter and the expected current; performing first value function calculation according to an equivalent two-level vector set composed of positive and negative small vectors to obtain an optimal small vector; calculating a second value function according to the equivalent two-level vector set where the optimal small vector is located to obtain a suboptimal vector; according to the characteristic that the vector action time is inversely proportional to a value function, the action time of an optimal small vector and the action time of a suboptimal vector are calculated; and applying a switching signal under the combined action of the optimal small vector and the suboptimal vector to a three-level inverter. According to the method, the vector set equivalent to two levels is established, so that the vector optimization process is simplified, and the model calculation time is greatly shortened; a value function of a single control target is established, and the tedious design process of weight factors is omitted; and a double-vector model predictive control method is adopted, so that output current harmonics are reduced.

The invention belongs to the technical field of electronic power, and particularly relates to a multi-target hybrid modulation method, system and equipment for a T-type three-level inverter, and the method comprises the steps: firstly, judging whether the inverter operates at an extremely low modulation degree or not; if yes, calculating theoretical midpoint current of the DPWM1 mode and the DPWM3 mode in parallel, and expanding midpoint current corresponding to four hybrid modulation modes generated after a VSVPWM sequence is introduced in the two modes respectively; then dynamically selecting an optimal hybrid modulation mode or returning to a basic DPWM mode according to the numerical relationship between the real-time calculated midpoint compensation current and each midpoint current; and finally, a three-phase double-modulation wave is generated, and PWM signals for driving all power switches are output after carrier wave comparison. According to the method, multi-objective optimization of the neutral point potential, the switching loss and the output waveform under the extreme working condition is realized, and the stability and the performance of the system are remarkably improved.

The invention discloses a T-type inverter fault diagnosis method based on a CWGAN and a TCN-SE network, relates to the fault diagnosis technology of power electronic equipment, and provides the scheme for solving the problem that the diagnosis precision is limited in the prior art. Acquiring three-phase current signal data output by the load side of the T-type three-level inverter; performing time sequence feature extraction on the three-phase current signal data through a TCN-SE network; wherein the TCN-SE network comprises a plurality of time sequence convolution modules, an SE attention module and a full connection layer, and the time sequence convolution modules adopt a one-dimensional convolution kernel to perform feature extraction on an input sequence; enhancing the original fault sample based on the CWGAN; inputting the features extracted by the TCN-SE network into a classifier for fault identification, wherein the classifier outputs the probability of each type of fault by adopting a Softmax function; the method has the advantages that the fault diagnosis accuracy is improved; the robustness and generalization ability are enhanced; self-adaptive extraction of time sequence features is realized; the small sample training effect is optimized; the diagnosis efficiency is improved.

The invention discloses an open-winding dual three-level ANPC inverter with fault-tolerant capability and a fault-tolerant control method capable of simplifying the modulation process of the two three-level inverters, an inverter topological structure comprises a first inverter and a second inverter, the first inverter and the second inverter are both active midpoint clamping three levels, and the first inverter and the second inverter are connected with each other. One side of the load is connected with a direct current side capacitor midpoint of the first inverter through three bidirectional thyristors, and the other side of the load is connected with a direct current side capacitor midpoint of the second inverter through three bidirectional thyristors. A carrier pulse width modulation method of superposing zero sequence components is adopted, and sector judgment and basic vector action time calculation are not needed, so that the modulation process is greatly simplified, and the calculation amount is reduced; and the adopted neutral-point potential voltage-sharing strategy can balance the capacitor voltage in an inverter fault-tolerant mode.

The invention provides a common-mode voltage suppression method for a three-level four-leg inverter, and relates to the technical field of power electronics. Aiming at the problem that the common-mode voltage is relatively high in the application of the existing three-level four-bridge-arm inverter, the invention proposes that two bridge arms in four bridge arms of the inverter are subjected to anti-sequence operation, so that the common-mode voltage is effectively inhibited; the method comprises the following steps: calculating terminal voltages of four bridge arms, selecting a bridge arm for performing desequencing operation based on a desequencing operation bridge arm pairing rule, and adjusting a modulation waveform of each bridge arm; compared with a traditional three-level inverter modulation method, simulation comparison analysis shows that the common-mode voltage is remarkably reduced; the common-mode voltage performance comprehensive comparison of the six anti-sequence modes shows that the anti-sequence operation used in the method has the optimal performance.

The invention relates to the technical field of energy storage converters, in particular to a three-level inverter DPWM and SVPWM smooth switching method and system, a medium and equipment, and the method comprises the steps: determining a current modulation mode which comprises the SVPWM and the DPWM; a first modulation coefficient and a second modulation coefficient are set, the first modulation coefficient corresponds to the weight of the SVPWM common-mode voltage, the second modulation coefficient corresponds to the weight of the DPWM common-mode voltage, and the sum of the first modulation coefficient and the second modulation coefficient is constantly 1; determining values of a first modulation coefficient and a second modulation coefficient based on the current modulation mode in response to a switching instruction of switching from the current modulation mode to a target modulation mode; and combining the three-phase SPWM modulation wave, the first modulation coefficient, the SVPWM common-mode voltage, the second modulation coefficient and the DPWM common-mode voltage to generate a total modulation wave. According to the invention, non-stop switching of SVPWM and DPWM is realized, fast and stable neutral-point voltage and smooth transition of neutral-line current and three-phase current are ensured when two modulation modes are switched, and the smooth transition requirement of mode switching is met.

The invention discloses a common-mode voltage suppression and neutral-point voltage self-balance control method for a parallel NPC type three-level inverter system. The method comprises the following steps: (1) constructing a parallel NPC type inverter system structure model based on an NPC type three-level inverter; (2) determining a three-phase reference voltage vector in the three-phase static coordinate system according to a three-phase sine wave needing to be output, and converting the reference voltage vector in the three-phase static coordinate system into an alpha-beta coordinate system; (3) determining a sector where the vector is located and an area where the vector is located according to the amplitude of the reference voltage vector in the alpha-beta coordinate system and an included angle between the reference voltage vector and the alpha axis; (4) selecting a corresponding zero common mode basic vector combination according to the large sector and the small sector where the reference voltage vector is located and in combination with the basic output voltage vector; (5) calculating the action time of the basic vector in each sector; (6) distributing a basic vector action sequence according to a volt-second balance principle to realize neutral-point potential balance; according to the invention, common-mode voltage suppression and neutral-point voltage self-balancing are realized.

The invention relates to a control method of a three-level inverter, a motor driver and a vehicle. The control method comprises the following steps: acquiring a first voltage at two ends of a first bus capacitor, a second voltage at two ends of a second bus capacitor, a reference current of the three-level inverter and a modulation voltage corresponding to each phase line on the alternating current side of the three-level inverter; determining an initial accumulated charge based on the first voltage and the second voltage; determining a zero-sequence injection voltage based on the reference current, the modulation voltage corresponding to each phase line and the initial accumulated charge; determining a target modulation voltage corresponding to each phase line according to the modulation voltage corresponding to each phase line and the zero-sequence injection voltage; and outputting a target modulation signal to the three-level inverter according to the target modulation voltage. Obviously, the probability of midpoint voltage deviation can be effectively reduced through the zero-sequence injection voltage, interference in the control process of the three-level inverter is reduced, the output quality of the target modulation signal is improved, and the control efficiency of the three-level inverter is improved.

The invention discloses an inverter IGBT intelligent fault diagnosis method based on a multi-scale attention network, and relates to the technical field of power electronic equipment fault diagnosis. A three-phase current signal of a three-level NPC inverter is collected and preprocessed; multi-dimension fault features of the current signals are extracted in parallel through multi-scale depth separable convolution; a scale-aware efficient attention mechanism is introduced to carry out weighted optimization on each scale feature, and key fault information is strengthened; and outputting a fault diagnosis result through a feature fusion and classification network, and performing INT8 quantization processing on the model to adapt to an embedded deployment scene. The method has the advantages of being high in multi-scale feature capturing capacity, high in diagnosis precision and light in model weight, and can meet the dual requirements of industrial application for real-time performance and accuracy.

The present application is applicable to the technical field of inverter control, and provides an improved vector pulse control method for a T-type three-level inverter, and a related device. The method comprises: constructing a dynamic equation of alternating current sides of a plurality of parallel T-type three-level inverters; determining a reference voltage vector within a control cycle on the basis of the dynamic equation; determining a zero-sequence duty ratio difference of two parallel inverters on the basis of the reference voltage vector and an SVPWM switching time sequence in sector areas, the SVPWM switching time sequence comprising a control variable for vector time adjustment; determining circulating current of each sector area and the control variable on the basis of the dynamic equation, the reference voltage vector and the zero-sequence duty ratio difference; and performing circulating current control on the basis of the control variable. According to the present invention, the control variable for vector time adjustment can be accurately calculated, and compared with direct giving of the variable, the precision is higher, the control strategy is simple, the output current waveform can be better improved, the harmonic of the output current of a system is reduced, and the stability of grid-connected operation of the system is improved.