42 results about "PWM rectifier" patented technology

The invention provides a PWM / Buck cascade circuit auxiliary electrolytic hydrogen production rectification power supply and a control method, and relates to the technical field of electrolytic hydrogen production power supply and intelligent power grids, and the power supply comprises a main power loop and an auxiliary power loop; the main power loop comprises a multi-pulse thyristor rectifier, the power supply side of the multi-pulse thyristor rectifier is connected with an alternating-current power grid, the load side of the multi-pulse thyristor rectifier is connected with one end of a direct-current smoothing reactor, and the other end of the direct-current smoothing reactor is connected with the electrolytic bath; the auxiliary power loop comprises a PWM rectifier and a Buck circuit which are connected in series, the output end of the Buck circuit is connected to the output end of the main power loop in parallel through a direct-current LC filter, the output end of the Buck circuit and the output end of the main power loop are jointly connected into an electrolytic bath for ripple compensation, the multi-pulse rectifier adopts PI control, the PWM rectifier adopts voltage and current double-closed-loop control and SVPWM modulation, Buck adopts PI and feedforward compound control, and the output end of the Buck circuit and the output end of the main power loop are connected in parallel. The system has the advantages of improving the grid-side electric energy quality, the voltage utilization rate, the water electrolysis hydrogen production efficiency and the operation stability.

The application provides a non-continuous three-phase rectifier adjustable power decoupling method, and relates to the field of power electronics. The method is characterized in that a capacitor equivalent circuit is connected in parallel to the DC side of a three-phase PWM rectifier, the capacitor equivalent circuit is composed of a first capacitor connected in series with an active negative capacitor circuit, and a digital signal controller is used to sample the relevant voltage and current signals of the AC side and the DC side, and the active negative capacitor capacitance is adjusted by controlling the switching tube, so that the equivalent capacitor circuit can be flexibly adjusted. The application does not require an additional DC power supply, the capacitance and inductance of the passive device used are small, and the volume advantage is significant. The closed-loop control has high precision and equivalent inhibition effect as the traditional large capacitor. The equivalent capacitance is adjusted only by software, the external physical structure does not need to be changed, and the adjustment range is wide. The preset DC side voltage fluctuation amplitude can be calculated and adjusted automatically, different unbalanced working conditions can be adapted, the fluctuation suppression demand can be met, different working modes can be switched according to the AC side working condition, and the application is not continuously operated, so that the switching loss is lower.

The application discloses a parallel power supply current estimation method based on an instantaneous power integration method and relates to the technical field of power electronics and power supply control. The method collects electrical signals on the AC side of a three-phase PWM rectifier in front of each power supply module, calculates the instantaneous power input of the module, and integrates the input power and the voltage on the load side with the switching period of a DC-DC converter in back as an integration window to obtain the single-period energy and voltage integration value, so as to weaken the influence of the energy of energy storage elements such as inductors and capacitors in the circuit on the estimation result, thereby obtaining the preliminary estimation value of the output current of the module. Meanwhile, an independent equivalent loss resistor is introduced for each power supply module to describe the loss in the power supply, and the equivalent loss resistor is estimated in a longer time scale through an offline polling mode, so as to obtain the output current estimation result of each parallel power supply module.

This application provides a control method, system, and electronic device for a PWM rectifier. The control method includes: determining the actual current of the PWM rectifier and determining a current error based on the actual current and a reference current; obtaining a first control parameter based on the current error using a preset algorithm; determining an error compensation value based on the current error using a repetitive controller, and compensating the first control parameter with the error compensation value to obtain a second control parameter; determining the fundamental frequency of the modulation wave based on the second control parameter, and obtaining a control signal based on the fundamental frequency of the modulation wave using a discontinuous pulse width modulation (DPWM) method to control the PWM rectifier. This application introduces a repetitive controller into the discontinuous pulse width modulation (DPWM) method, which improves the problem of large current harmonics caused by periodic errors due to periodic entry into clamping state in the DPWM modulation method, thereby improving control accuracy.

The invention discloses a three-phase voltage type PWM rectifier switch tube open-circuit fault diagnosis method, which comprises the steps of 1, implementing three-layer wavelet decomposition on an input side three-phase current historical database after a three-phase voltage type PWM rectifier power switch tube open-circuit fault by adopting a wavelet decomposition method, extracting a characteristic value corresponding to the switch tube fault and finishing normalization; and 2, performing parameter optimization on the support vector machine through an improved mouse group search algorithm, and determining an optimal penalty factor and a kernel parameter so as to carry out data training and fault diagnosis. The invention aims to analyze the waveform distortion condition of the three-phase current at the input side after the open-circuit fault of the three-phase rectifier switch tube, so as to optimize the fault characteristic quantity and realize the accurate diagnosis of the open-circuit fault of the power switch tube. According to the invention, the fault identification capability of the rectifier system under the abnormal working condition can be effectively improved, so that safe and stable operation of power electronic equipment is ensured.

The invention discloses a 12 pulse wave / PWM hybrid rectifier based on multi-winding phase-shifting transformer power supply and a control method thereof, and relates to the technical field of hydrogen production equipment, and the 12 pulse wave / PWM hybrid rectifier comprises a three-phase AC power grid, a multi-winding phase-shifting transformer, a 12 pulse wave / PWM hybrid rectifier and an electrolytic cell. Wherein the additional winding of the multi-winding phase-shifting transformer adopts a type connection method, and provides a winding internal circulation path of harmonics of three times and multiple times of three; the control method comprises the steps of 12-pulse thyristor rectifier control, PWM rectifier control and DC-DC converter control, and a phase compensation mechanism is introduced for the phase difference generated by the main winding and the additional winding of the multi-winding phase-shifting transformer due to the structure. Through topology integration and an advanced coordination control strategy, the problems that in the prior art, water electrolysis equipment is complex, high in cost, large in harmonic wave and ripple wave, low in power factor, slow in dynamic response and the like are effectively solved.

The invention provides a battery self-checking control method for a bidirectional buck-boost system. The method comprises the steps that a first output signal is calculated based on a battery current reference value, a battery current sampling value and an inductive current sampling value, and the battery current reference value is a discharge current set during battery self-inspection; calculating a second output signal based on the bus voltage reference value, the bus voltage sampling value, the battery voltage sampling value and the battery current reference value; generating a duty ratio of a first driving signal for the charging and discharging circuit based on the first output signal; a duty cycle for a second drive signal of the PWM rectifier is generated based on the second output signal. On the basis of a bus voltage outer ring and a high-frequency inductive current inner ring, a battery current inner ring and a rectifier current inner ring are added, and under the condition of constant current discharge, the bus voltage is controlled together. Therefore, during self-inspection of the battery, the stability of the bus voltage can be maintained while the battery is ensured to be discharged at a constant current.

The invention discloses a method for calculating secondary ripple current of a single-phase PWM (Pulse Width Modulation) rectifier, which comprises the following steps of: A, obtaining input voltage us and input current is of the rectifier through sampling, and respectively obtaining orthogonal components us alpha and us beta of the voltage and orthogonal components is alpha and is beta of the current through orthogonal transformation or delay of a quarter period; respectively calculating a voltage amplitude Us and a current amplitude Is; the included angle between the input voltage and the current is phi, namely a power factor angle; b, the active power P and the reactive power Q of the input power of the rectifier are calculated, and then the power factor angle phi of the grid-side current and the voltage is calculated; obtaining the angular velocity omega of the input voltage by using a phase-locked loop; c, according to the inductance value L, the voltage amplitude Us, the current amplitude Is, the power factor angle phi and the angular velocity omega of the PWM rectifier, the alternating current side secondary pulsation power Pshc of the rectifier is calculated; and D, calculating the secondary ripple current of the DC side of the PWM rectifier in real time by using the PWM DC side given voltage Vdcref and the AC side secondary pulse power Pshc. The method is different from a method for obtaining the reference value of the secondary ripple current on the DC side of the PWM rectifier by adopting current sampling and filtering and the like, and the reference value of the secondary ripple current is directly calculated by directly utilizing the existing parameters of the PWM rectifier; and the precision of the secondary ripple current reference value is further improved on the basis of eliminating a current sensor and a circuit thereof.

The application discloses a control method of a diesel-electricity-fuel combined propulsion system, a six-dimensional mathematical model of a six-phase induction motor is established first, then space decoupling transformation is carried out on the mathematical model, a mathematical model of the six-phase induction motor based on a synchronous rotating coordinate system d-q is established, mathematical models of a three-phase voltage type PWM rectifier and a three-phase voltage type PWM inverter are respectively established, and finally, six-phase induction motor double-dq vector control based on SVPWM is carried out; under the motor follow-up power generation condition, the output power of the gas turbine is higher than the total output power of the propulsion system, the redundant power is provided to the motor by the transmission shaft, the motor is driven to generate power, and the requirement of a 10kV level network on harmonics is met.

The application discloses a kind of based on working condition self-adaptive machine tool PWM rectifier energy-saving control method and system, wherein the method comprises the following steps: numerical control system real-time acquisition machine tool operating condition and using operation mode judgment strategy to process and obtain operation mode instruction, operation mode instruction is input to the controller of PWM rectifier, and operation mode instruction includes static rectification mode and PWM rectification mode;The controller of PWM rectifier obtains operation mode instruction and controls PWM rectifier to enter corresponding working mode, when the controller of PWM rectifier obtains static rectification or PWM rectification mode instruction, the controller of PWM rectifier can close or open the high-frequency switching action of PWM rectifier internal power device, so that PWM rectifier only utilizes the diode characteristics of power device or switch and carries out static or normal rectification.The disclosed method can control PWM rectifier to work in different modes according to the operating condition of machine tool, and energy saving can be effectively realized.

The application provides a kind of hybrid vector variable frequency control method based on three-phase rectifier, it is related to power electronic electric energy conversion technical field;Current three-phase PWM rectification technology is important front-stage equipment, and the current of switch tube is large, and the loss of switch tube is composed of turn-on loss and conduction loss, and conduction loss cannot be avoided in high-power state, and switch loss is related to frequency, if switch tube loss is not controlled, switch tube loss will accumulate in the form of heat, when temperature exceeds the limit of switch tube, it often causes irreversible damage to switch tube, therefore, on the basis of considering the power quality of DC side, the action frequency of switch tube of three-phase PWM rectifier is dynamically controlled to realize the continuous operation of three-phase PWM system under high power, and the method considers the stability of DC side voltage and the temperature characteristics of IGBT to carry out frequency modulation.

The invention provides a two-stage hydrogen production power supply device with a self-adaptive virtual impedance adjusting function, which comprises a two-stage converter scheme which is composed of a three-phase voltage source type PWM (Pulse Width Modulation) rectifier and an interleaved Buck circuit and is used for providing direct-current electric energy for an electrolytic bath; the running state detection unit is used for collecting voltage, current and other parameters of the electrolytic cell and judging the running condition; corresponding virtual impedance compensation control is carried out according to the operation condition of the electrolytic cell, and the steady-state characteristic and the dynamic characteristic are improved; and the virtual impedance compensation amount of the power grid voltage is introduced for secondary adjustment so as to reduce the current and voltage fluctuation of the electrolytic cell end and improve the anti-harmonic and anti-voltage fluctuation capability of the system.

The application provides an electromagnetic damper type self-powered active / semi-active vibration reduction system and a method thereof, comprising a linear-rotation conversion device, an energy conversion device and a load, wherein the linear-rotation conversion device adopts a gear rack or a ball screw; the energy conversion device adopts a permanent magnet synchronous motor; the load is configured as a three-phase voltage type PWM rectifier and a battery; when the system works in an active mode, motor control force is solved by rolling optimization in a model predictive controller according to detected structural displacement, speed, voltage and current feedback information; when the system works in a semi-active mode, analog inertia force, stiffness force and damping force are calculated according to feedback signals, each bridge arm of the three-phase voltage type PWM rectifier is turned on and turned off to realize control of the motor, vibration is suppressed, and the energy of the vibration is recovered to the battery.

This invention discloses a method for diagnosing open-circuit faults in IGBT power devices of a single-phase PWM rectifier based on RVFL. This method obtains the original database of IGBT open-circuit faults based on an experimental platform and its digital simulation system, designs fault feature vectors, trains a fault classifier using an RVFL classifier, adjusts the number of nodes and activation function of the network model to save computational resources and time, and uses the trained network model to classify and identify online acquired data samples. This solves the problem of real-time and rapid diagnosis of IGBT open-circuit faults in single-phase PWM rectifiers and is beneficial for the real-time online operation of fault diagnosis algorithms.

The invention discloses a 3300V mining frequency converter energy feedback system based on a PWM rectifier, and the system comprises an input filtering module which is used for carrying out the filtering of the voltage and current of a power grid side, and obtaining an input voltage and an input current; the rectifying unit is used for rectifying the input voltage and the input current to obtain direct voltage and direct current; the direct-current bus is used for bearing direct-current voltage and current output by the rectification unit and providing stable direct-current power supply support for the inversion unit; the inversion unit is used for converting the direct-current voltage and the direct-current current in the direct-current bus into alternating-current voltage and alternating-current current and outputting the alternating-current voltage and the alternating-current current to a motor; the detection unit is used for detecting voltage and current values of other modules; and the main control unit is used for controlling the rectification module or the inversion module based on the voltage and current values, detected by the detection unit, of other modules, so that efficient utilization of energy is realized, and the stability and safety of rectifier control in a high-voltage scene are improved.

The invention provides a station-level modeling method for large-scale vehicle network interaction, which comprises the following steps: 1) constructing an electromagnetic transient simulation model library in a station-level simulation device for large-scale vehicle network interaction, the electromagnetic transient simulation model library comprising a binary resistance model, an average value model and a constant admittance model; 2) constructing a charging and discharging motor model suitable for the charging and discharging process of the electric vehicle, wherein the charging and discharging motor model is formed based on a three-phase voltage type PWM rectifier and a bidirectional DC / DC converter; 3) based on the electromagnetic transient simulation model library and the charging and discharging machine model, establishing a large-scale vehicle-network interaction station-level digital simulation system, constructing a large-scale vehicle-network interaction station-level model, and connecting all charging piles in parallel to a power grid node by adopting a common alternating current bus framework to realize simulation of a dynamic interaction process in a large-scale electric vehicle grid-connected scene; the problem that an existing vehicle network interactive simulation model cannot accurately simulate electrical coupling and impedance interaction generated during parallel operation of multiple charging piles under a station-level scale is solved.

The application provides a network-constructed V2G intelligent charging and discharging method, device, system and storage medium, relates to the technical field of data processing, and the method comprises the following steps: detecting the voltage and current information of the power grid and the coupling point of the device through the signal acquisition unit of the network-constructed V2G charging and discharging device, and determining the operation condition of the power grid; based on the operation condition of the power grid, the model prediction control algorithm is used to optimize the charging and discharging strategy, the target of supporting the voltage / frequency of the power grid is given priority to under the weak power grid condition, and the target of maximizing the charging and discharging benefit is given priority to under the normal condition; according to the optimized charging and discharging strategy, the working mode of the three-phase voltage type PWM rectifier and the bidirectional DC / DC converter in the main circuit is controlled, and the rectification or inversion state is switched; in the charging and discharging process, the active power and the reactive power are independently adjusted, the voltage / frequency support and the reactive power compensation of the power grid are realized; the state of charge of the electric vehicle battery and the operation state of the device are monitored in real time, and are fed back to the control unit.

The application discloses a three-level PWM rectifier fast modulation and neutral point potential balance control method, which comprises the following steps: 1) according to a mathematical model of the three-level PWM rectifier, a modulation model of the three-level PWM rectifier is established based on the mathematical model and constraint conditions of duty ratios of nine switch tubes; 2) a basic solution system and a special solution of a linear equation set are utilized to decompose free components of a modulation process, and different modulation strategies are obtained by appropriately selecting different free components; and 3) a control strategy that AC components of duty ratios of three zero potential switches should be in-phase with three-phase currents is proposed, and solving of an inequality with four degrees of freedom is reduced to one, and finally a value range of one degree of freedom is determined. According to the inequality constraint, the modulation result is solved, and the calculation workload is small and the speed is fast; the proposed neutral point balance control strategy reduces the duty ratio fluctuation range of the three zero position switches, thereby providing a larger space for voltage or current control of the three-level PWM rectifier.

This invention discloses a high-power superconducting magnet power supply system and control method with controllable positive and negative rates. The system includes an input stage, an intermediate stage, and an output stage. The input stage is a three-phase full-bridge voltage-type PWM rectifier circuit, connected to a three-phase power grid. The intermediate stage is a modular DAB converter composed of three cascaded dual active bridges, connected to the input and output stages. The output stage is an H-bridge structure, connected to the high-power superconducting magnet. By controlling the power switches in individual DAB and H-bridge circuits using PWM, the high-power superconducting magnet can be magnetized and demagnetized at controllable rates. This power supply system consists of three stages: an input stage, an intermediate stage, and an output stage. The control method, combined with the circuit topology, is simple, efficient, and easy to implement. It effectively controls the charging and discharging rate of the high-power superconducting magnet and feeds electrical energy back to the power grid during discharge.

The invention discloses a current source type PWM rectifier control method, and relates to the field of rectifier control. The method comprises the following steps: firstly, carrying out small-signal linearization modeling on a circuit topology of a current source type PWM rectifier control system, and establishing an open-loop transfer function of the system before and after active damping is added; secondly, damping parameters are designed through active damping, and the influence of series resonance of the output LC filter is restrained; on the basis, a switching loss optimization modulation strategy is designed, and the modulation performance of the system is further improved; and finally, setting a voltage and current double-closed-loop controller, determining controller parameters of a current inner loop and a voltage outer loop, and realizing optimization of the control performance of the current source type PWM rectifier control system. The control method is provided for the current source type PWM rectifier, and the current source type PWM rectifier has the advantages of being good in tracking performance, dynamic response speed and operation stability, high in power factor, low in input current harmonic wave and the like.

The invention discloses a parallel power supply current estimation method based on an instantaneous power integration method, and relates to the technical field of power electronics and power supply control. According to the method, electric signals of the alternating current side of a preceding-stage three-phase PWM rectifier of each power module are collected, module input instantaneous power is calculated, integration is carried out on the input power and load side voltage by taking the switching period of a backward-stage DC-DC converter as an integration window, and single-period energy and a voltage integration value are obtained; the influence of energy round-trip of energy storage elements such as an inductor and a capacitor in the circuit on an estimation result is weakened, so that a preliminary estimation value of module output current is obtained; meanwhile, an independent equivalent loss resistor is introduced for each power supply module to describe loss in the power supply, setting is carried out in an off-line polling mode, and the equivalent loss resistor is estimated in a longer time scale by an integration method, so that an output current estimation result of each parallel power supply module is obtained.

This invention discloses a three-phase Buck-Boost PWM rectifier and its control method. The rectifier includes a Buck rectifier unit, a first Boost boost unit, a second Boost boost unit, and a common-mode current suppression unit. The positive output terminal of the Buck rectifier unit is connected to the load via the first Boost boost unit, and the negative output terminal of the Buck rectifier unit is connected to the load via the second Boost boost unit. The common-mode current suppression unit is a capacitor C. mn Capacitor C mn One end of the capacitor is connected to the neutral point of the three-phase input filter capacitor, and capacitor C... mn The other end is connected to the intermediate connection node between the first Boost unit and the second Boost unit, as well as the intermediate connection node between the positive and negative output terminals of the Buck rectifier unit. The advantage of this invention is that it avoids the influence of parasitic capacitance on the quality of its input current and improves the quality of the input current.

The invention discloses a PWM rectifier fixed frequency prediction control method and system under three-phase imbalance, and relates to the technical field of power electronic control, and the method comprises the steps: building a three-phase PWM rectifier current prediction model under the three-phase imbalance state; predicting the active power of the next control period and the dynamic change of the d-axis positive-negative sequence current and the q-axis positive-negative sequence current based on the prediction model; based on the dynamic change, constructing a combined value function containing d-axis and q-axis positive and negative sequence current errors and active power errors, and obtaining an optimal modulation action time distribution strategy by minimizing the combined value function; generating a control signal according to an optimization result by adopting a space vector pulse width modulation technology; according to the method, independent adjustment of positive and negative sequence current is effectively realized by comprehensively considering a value function which takes d and q axis positive and negative sequence current errors and active power errors as targets under the condition of three-phase power grid voltage imbalance, and high-precision tracking and optimal scheduling of the active power of the system are ensured.

The invention relates to the technical field of rectifier small signal matrix modeling, in particular to a PWM rectifier small signal matrix modeling method, system and device and a medium, and the method comprises the steps: carrying out the frequency domain analysis of a sine pulse width modulation process based on an impulse sampling principle, and constructing a spectrum mapping matrix representing an SPWM modulator; expanding at least one linear link in the PWM rectifier control system into a diagonal matrix model in a frequency domain; and integrating the spectrum mapping matrix with the diagonal matrix model of the at least one linear link, and obtaining a multi-frequency coupling closed-loop matrix model of the PWM rectifier system through matrix operation. The method has the beneficial effects that the dynamic response characteristics of the PWM rectifier on fundamental waves and various sideband harmonics can be accurately and quantitatively analyzed, and the defects that a traditional average model cannot represent high-frequency switching behaviors and the problems of difference frequency oscillation, harmonic coupling and the like caused by the high-frequency switching behaviors are solved; and an accurate model basis is provided for high-frequency stability analysis and advanced control strategy design.

The application discloses a two-stage parallel high-power hydrogen production power supply system and a non-contact line current sharing control method thereof in the technical field of power supply or distribution circuit, which comprises a three-phase power supply, the three-phase power supply is connected with input ends of two PWM rectifiers respectively, output ends of each PWM rectifier are connected with input ends of two DC / DC converters, and output ends of the two DC / DC converters are connected with a hydrogen production PEM device, wherein the three-phase power supply, the PWM rectifier DC output end and the DC / DC output end are parallel operation; the conventional topology is improved, high reliability and low cost are considered, the application proposes a non-isolated three-phase power supply, PWM rectifier output end and DC / DC converter output end "three-end direct parallel" system architecture. The architecture effectively breaks the bottleneck that single-stage failure leads to the failure of the whole module, higher system-level reliability can be provided through fewer redundant devices; reasonable distribution and loop current suppression of the parallel system power are realized.

The application discloses a kind of integrated charging circuit of electric vehicle of no winding switching switch and electrolytic capacitor and its control strategy.The system is switched from driving operation mode to charging operation mode, only needs single-phase charging access switch and low-voltage battery charging switch, without additional motor winding switching switch, it can be reconstructed into single-phase PWM rectifier and parallel Buck converter with active filter for common bus double three-phase bridge inverter drive circuit, simultaneously charging for vehicle-mounted high-voltage power battery and low-voltage auxiliary battery, and for the asymmetric characteristics of motor winding resistance and inductance parameters, steady-state torque ripple suppression strategy is added during charging operation, reduces the secondary current harmonic of DC side, effectively reduces the vibration and noise during charging, improves the safety and reliability of electric vehicle integrated charging.

This invention relates to the field of charge / discharge power conversion control for electrochemical energy storage batteries, and provides a battery energy storage converter and fault-tolerant control method. The converter includes multiple cascaded sub-units, each comprising a battery module, a PWM rectifier stage, a DC boost stage, and a switching switch. The PWM rectifier stage contains a series capacitor on its DC side, and the DC boost stage is a resonant soft-switching circuit. By switching the state of the switching switch, the battery module can be directly connected to the PWM rectifier stage or connected to the DC boost stage. This invention eliminates boost losses during normal operation and utilizes the resonant soft-switching circuit to efficiently boost and compensate for voltage during faults, significantly reducing switching losses and improving system operating efficiency and reliability.

The application provides a current-mode PWM rectifier and a passive control method thereof, comprising a filter unit, a rectifier unit and a load unit connected in sequence; an input end of the filter unit is connected with a three-phase AC source, an output end of the filter unit is connected with an input end of the rectifier unit, a first output end of the rectifier unit is connected with an input end of the load unit, and a second output end of the rectifier unit is connected with an output end of the load unit; the filter unit is used for filtering high-order harmonics of the three-phase AC source received by the current-mode PWM rectifier on an AC side; the rectifier unit is used for rectifying a filtered voltage to obtain a rectified voltage; and the load unit is used for converting the received rectified voltage to realize energy output. The application can realize independent decoupling control of active power and reactive power and unit power factor control, can also be used for reactive power compensation function, and has the advantages of few control parameters, convenient debugging and strong anti-interference capability.

The invention discloses a micro-grid system and a control method thereof, and the system comprises a DC power grid, N PWM rectifiers which are connected in parallel, an industrial frequency transformer, an AC power grid, and new energy equipment. Wherein N is greater than or equal to 2; a direct-current port of each PWM rectifier is connected with the direct-current power grid, an alternating-current port of each PWM rectifier is connected with the low-voltage side of the industrial frequency transformer, and the new energy equipment is connected with the alternating-current power grid and then connected with the high-voltage side of the industrial frequency transformer; the micro-grid system controls each PWM rectifier to work in a quadrant through a plurality of energy flow modes so as to realize grid construction and energy transmission. By adopting the method, the power distribution balance and the electric energy quality of the micro-grid system can be improved, the hidden danger of communication delay is eliminated, the new energy fluctuation is flexibly adapted, and the safety and the stability of the system are enhanced.

This invention discloses a method and system for fault diagnosis and fault-tolerant control of a single-phase PWM rectifier sensor, considering the non-ideal characteristics of switching devices. The method includes: establishing a mathematical model of the single-phase PWM rectifier, transforming the non-ideal characteristics of the switching devices into a non-ideal switching function; establishing a state-space model of the single-phase PWM rectifier considering the non-ideal characteristics of the switching devices, designing an adaptive sliding mode observer, and tuning its parameters to provide an adaptive law for compensating for the ideal switching function; establishing fault residuals of the AC side current and DC side voltage of the single-phase PWM rectifier based on the adaptive sliding mode observer, performing fault diagnosis, locating the faulty sensor, and using the observation value of the adaptive sliding mode observer to replace the value collected by the faulty sensor for feedback and closed-loop control until the fault is eliminated, thus achieving fault-tolerant control. This invention improves the fault tolerance capability of the single-phase PWM rectifier under AC side current or DC side voltage sensor fault conditions.