140 results about "Magnetizing inductance" patented technology

Provided is a resonant converter capable of adaptively tuning a quality factor based on load. The resonant converter includes a resonant tank having an inductor part whose inductance is tunable according to a first control potential, a magnetizing inductor, and a capacitor part whose capacitance is tunable according to a second control potential. The resonant converter detects the rectifying current of its output stage for responding to the load state of the resonant converter. The resonant converter outputs the first and second control potentials in response to the load state, tuning the equivalent inductance of the inductor part, the equivalent capacitance of the capacitor part, or both, thereby changing the quality factor of the resonant converter.

A power converter includes a transformer, a resonant circuit, a switch circuit, a resonant adjustment circuit, and a controller. The transformer includes a primary-side winding, a secondary-side winding, and a magnetizing inductance. The resonant circuit includes a first resonant capacitor, and the switch circuit includes a first switch and a second switch. The resonant adjustment circuit is coupled to the first resonant capacitor, and the controller is coupled to the resonant adjustment circuit. The controller controls the resonant adjustment circuit to adjust a resonant current flowing through the first resonant capacitor according to an output voltage of the power converter so as to adjust a current value that when the resonant current and a magnetizing current flowing through the magnetizing inductance intersect to be substantially equal to a predetermined value.

The invention belongs to the field of transformer pile head recognition, and particularly relates to a distribution transformer pile head automatic recognition system which comprises a data integration module, a data processing module, a system control module, a waveform parameter calculation module, an excitation circuit analysis module, an equivalent inductance conversion module and a looseness recognition algorithm module. According to the scheme, the high-cost limitation of a traditional vibration sensor or 3D modeling is broken through, and remote monitoring of looseness of the transformer pile head can be achieved through equivalent excitation inductance conversion and waveform similarity analysis without additional hardware transformation based on voltage and current data collected by an existing digital platform (a resource middle platform, a marketing middle platform and the like) of a power grid. Compared with the traditional scheme in the industry, the method has the advantages that the hardware transformation cost is reduced by more than 70%, the problem of missing inspection of manual inspection is avoided, the average recognition time of the pile head loosening fault is shortened to be within 15 minutes from 4 hours of traditional manual inspection, the monitoring efficiency is remarkably improved, and non-intrusive and low-cost accurate sensing of the state of the transformer is realized.

The invention discloses an excitation inductance design method for guaranteeing soft switching of a CLLC resonant converter, and the method comprises the steps: carrying out the qualitative analysis of a dead-zone equivalent circuit of the CLLC resonant converter, and carrying out the Laplace coordinate transformation. And according to the constant frequency analysis principle of the CLLC resonant converter, obtaining the electric quantity values of the capacitor and the inductor at the dead zone moment. And obtaining a resonance current time domain expression in a dead zone period by adopting a mesh current method. And calculating the period of the resonance current according to the parasitic capacitance values of the primary and secondary side switching tubes. And calculating the discharge time of the parasitic capacitor by considering the electric quantity of the capacitor. And calculating the excitation inductance value required when the resonance current just drops to zero when the dead time is ended. Soft switching of the resonant converter can be effectively guaranteed, the amplitude of the resonant current is reduced, the efficiency of the resonant converter is improved, and the universality is high.

The invention relates to the technical field of electric variable data compensation, in particular to a metering error dynamic compensation method and system of an intelligent measuring switch. The method comprises the following steps: calculating to obtain phase delay compensation time of each sampling point based on original instantaneous current of each sampling point, equivalent excitation inductance of a current transformer, internal resistance of a secondary side winding, resistance value of a sampling resistor and a magnetic circuit saturation critical current value; performing high-order correction on the original instantaneous current to obtain a real current value of the sampling point; based on the original instantaneous voltage, the real current value and the phase delay compensation time of the sampling point in the metering period, the active power of the metering period is calculated so as to realize metering error dynamic compensation, and the accuracy of active power calculation of the intelligent measurement switch in the dynamic load switching process can be effectively improved.

The invention discloses a three-phase single-stage alternating-current and direct-current converter and a control method and device thereof, which are used for improving the conversion efficiency and the power density of the alternating-current and direct-current converter. The converter comprises a three-phase matrix switch circuit, a resonance circuit, an isolation circuit and a rectification circuit. The three-phase matrix switch circuit is connected with three-phase alternating current and comprises three switch branches which are independently arranged, each switch branch comprises an upper bridge arm and a lower bridge arm, the midpoint of the upper bridge arm and the midpoint of the lower bridge arm in each switch branch are connected with one phase of alternating current input, and each bridge arm comprises a bidirectional switch assembly or two switch assemblies which are reversely connected in series; the resonant circuit comprises a resonant capacitor, a resonant inductor and an excitation inductor which are connected in series, and is connected between the common endpoint of the upper bridge arms and the common endpoint of the lower bridge arms of the three switch branches; one side of the isolation circuit is connected with the resonance circuit, and the other side is connected with the rectification circuit; and the rectification circuit comprises at least two switch assemblies, the input side is connected with the isolation circuit, and the output side is connected with load equipment.

A power supply includes a converter circuit, a switching circuit and a control circuit. The converter circuit includes a transformer, a primary side switch and a secondary side switch. The switching circuit includes first and second capacitors, first and second sets of switches. In a first phase, the primary side switch is in the conduction state, causing a magnetizing inductor of the transformer to store energy. In a second phase, the primary side switch is in the off state, causing the magnetizing inductor to release the energy. In a first mode of the second phase, a first amount of the energy is transferred through the first set of switches to the first capacitor. In a second mode of the second phase, a second amount of energy is transferred to the second capacitor through the second set of switches.

The invention belongs to the technical field of key power supply conversion in an aviation airborne starting power converter, and discloses a novel matrix LLC secondary side resonant topology. On the basis of an LLC resonant topology circuit, a resonant cavity is placed on the secondary side of a transformer, a matrix transformer with the primary side connected in parallel and the secondary side connected in series is adopted, and the matrix transformer comprises n parallel H-bridge inversion units on the low-voltage side, a high-frequency matrix transformer, the LLC resonant cavity on the high-voltage side and a full-bridge uncontrollable rectification circuit. The matrix transformer is composed of n transformer units, primary sides of which are connected in parallel and secondary sides of which are connected in series. A primary winding of each transformer unit is connected with the H-bridge DC-AC inverter circuit. According to the matrix LLC secondary side resonant topology, by controlling the switching frequency of the H-bridge power MOS tube, square wave signals with different frequencies are obtained, the series impedance of the resonant capacitor and the resonant inductor is changed, the partial voltage at the two ends of the excitation inductor is adjusted, gain control over the resonant cavity is achieved, and the purpose of adjusting the output load voltage is achieved.

The invention discloses a bidirectional DC-AC converter control method considering a soft switching condition and current optimization. According to the invention, the switching loss of the converter is reduced by optimizing the phase shift angle and the switching condition of the converter, and the energy transmission efficiency is optimized by minimizing the effective value of the current, so that the performance of the whole sodium battery energy storage system is improved. Specifically, based on the relation between the excitation inductance Lm and the current effective value Iprms, the phase shift angle of the converter is accurately controlled, the current transmission efficiency is optimized, and it is ensured that the zero-voltage switching condition of a primary side bridge arm and a secondary side bridge arm can be achieved in the working process, so that the loss of the converter is remarkably reduced, and the energy conversion efficiency is improved.

The invention discloses a magnetic integrated structure suitable for a high-power LLC converter. The structure consists of two groups of magnetic cores which are symmetrically arranged up and down, wherein each group of magnetic cores comprises a U-shaped magnetic core and an I-shaped magnetic core which is matched with the inner side of a side column of the U-shaped magnetic core. The primary winding and the secondary winding of the transformer are both divided into two parts which are wound on the left magnetic core and the right magnetic core respectively, and the winding directions of the secondary winding on the magnetic column are opposite. Decoupling integration of functions of the inductor and the transformer is achieved by distributing the windings. In the design process of the PCB winding, the needed inductance value can be accurately adjusted by adjusting the area of the I-shaped strip-shaped magnetic core, and the inductance value error caused by the fact that the number of turns of the winding is the fraction is effectively avoided. Meanwhile, by changing the air gap of the magnetic core, the sizes of the excitation inductance and the resonance inductance can be flexibly adjusted in equal proportion. In addition, the planar windings are arranged on the two sides of the magnetic core respectively, the window area of the magnetic core is remarkably increased, the number of parallel stacking layers of the PCB windings on a single magnetic column is reduced, and therefore the heat dissipation performance of the transformer is improved.

The invention provides a resonant converter parameter optimization method and system of an electric vertical take-off and landing aircraft, and relates to the technical field of aviation power electronics. The method comprises the following steps: constructing an improved equivalent circuit model containing transformer secondary side leakage inductance; deriving a voltage gain function expression of the improved equivalent circuit model and an optimization calculation formula of the excitation inductance required for realizing the soft switching; parameter optimization is carried out based on the voltage gain function expression and the excitation inductance optimization calculation formula; and building an LLC resonant converter experimental prototype according to the optimized parameters, and carrying out system verification and performance evaluation. According to the invention, the problem of performance reduction caused by neglecting secondary side leakage inductance under a high-frequency working condition in a traditional design is solved, the efficiency, the voltage stabilization precision and the power density of the converter are remarkably improved, and the high requirement of eVTOL on an airborne power supply is met.

The utility model relates to the technical field of converters, in particular to a DAB converter adopting a bidirectional switch tap inductor, which comprises a primary side structure and a secondary side structure. The primary side structure comprises a direct current power supply Uin, an input capacitor Cin, a first power switch tube S1, a second power switch tube S2, a third power switch tube S3, a fourth power switch tube S4, a high-frequency inductor L, an excitation inductor Lm, a bidirectional switch tap inductor Lt and a transformer T; and the secondary side structure comprises a load resistor RL, an output capacitor Cout, a fifth power switch tube S5, a sixth power switch tube S6, a seventh power switch tube S7 and an eighth power switch tube S8. According to the converter, equivalent magnetization inductance is changed through bidirectional switch tap inductance, equivalent magnetization current is increased, zero-voltage switching-on is realized, switching loss is reduced, and the conversion efficiency is improved. When the input voltage and the output load are suddenly changed, good dynamic response capability is maintained, and zero-voltage switching operation is realized in a wide load and wide battery voltage change range.

The present invention discloses a method for designing an excitation inductor to ensure soft switching of a CLLC resonant converter, comprising a qualitative analysis of the dead-zone equivalent circuit of the CLLC resonant converter and a Laplace coordinate transformation. The electric quantity values ​​of the capacitor and the inductor at the dead-zone moment are obtained according to the fixed-frequency analysis principle of the CLLC resonant converter. The time-domain expression of the resonant current during the dead-zone is obtained by using the mesh current method. The period of the resonant current is calculated according to the parasitic capacitance value of the primary and secondary side switching tubes. The discharge time of the parasitic capacitance is calculated taking into account the electric quantity of the capacitor. The excitation inductance value required when the resonant current just drops to zero at the end of the dead-zone time is calculated. The present invention can effectively ensure the soft switching of the resonant converter, reduce the amplitude of the resonant current, improve the efficiency of the resonant converter, and has strong versatility.

A bidirectional DC / DC converter according to an embodiment of the present invention comprises: a transformer; a primary-side circuit connected to one side of the transformer and including a full-bridge circuit composed of first to fourth switches, a first resonant inductor, a magnetizing inductor, and a first resonant capacitor; and a secondary-side circuit connected to the other side of the transformer and including a full-bridge circuit composed of fifth to eighth switches, a second resonant inductor, a second resonant capacitor, and a third capacitor. In a mode in which power is supplied from the secondary-side circuit to the primary-side circuit among operation modes of the bidirectional DC / DC converter, the sixth switch is set to OFF, the eighth switch is set to ON, and the fifth switch and the seventh switch may be turned ON / OFF according to a first switching frequency.

The invention discloses a multi-resonant-state LLC converter based on an equal transformation ratio series transformer. The multi-resonant-state LLC converter comprises an inverter circuit, a resonant circuit, a transformer circuit and a rectifying circuit, the inverter circuit converts direct current into pulsating square waves, the resonance circuit comprises a resonance inductor, a resonance capacitor and excitation inductors or equivalent excitation inductors of the two transformers, and the resonance capacitor and the resonance inductor are connected in series and then matched with the excitation inductors to form an LLC resonance circuit. Different excitation inductance values of the two transformers are utilized to enable the resonant circuit to present a plurality of resonant states, and the multi-resonant states can effectively change current waveforms after secondary side rectification of the two transformers, so that rectification output current pulsation is reduced; the transformer circuit comprises two transformers with the same transformation ratio and different excitation inductances for electrical isolation and energy transfer; the rectifying circuit rectifies secondary alternating current of the transformer into direct current. According to the LLC converter, the problem of large rectification output current pulsation of the LLC converter can be solved, the consistency of the size of the transformer is realized, the power density and reliability of the converter can be improved, and the cost is reduced.

This application provides an output control circuit, a flyback converter, a chip, and an electronic device. The output control circuit can obtain a first output voltage from a first output circuit and a second output voltage from a second output circuit, and control the first and second output circuits to conduct sequentially based on the first and second output voltages in each switching cycle. Therefore, the output control circuit can determine a first freewheeling circuit and a second freewheeling circuit in the first and second output circuits, so that the magnetizing inductance of the transformer in the flyback converter transfers energy to the first and second freewheeling circuits respectively during the secondary freewheeling phase. That is, the magnetizing inductance transfers energy using high-frequency chopping in each switching cycle, making the high-frequency chopping frequency of the first and second output circuits equal to the switching frequency. Since the switching frequency is usually higher than the range of human hearing, the problem of audio noise can be solved, and the performance of the flyback converter can be improved.

The application provides an efficiency optimization control method and device of a bidirectional LLC converter, and belongs to the technical field of power electronic conversion. The method comprises the following steps: determining the converter working mode of the bidirectional LLC converter based on the low-voltage battery side current, and determining the on-off control instruction of the switching unit based on the converter working mode; the bidirectional LLC converter comprises a resonant inductor, a resonant capacitor, a transformer, an external excitation inductor and a switching unit; the resonant cavity instantaneous current is subjected to zero-crossing detection and reference timing extraction to obtain a resonant current zero-crossing time reference signal; the zero-crossing synchronization driving signal of the switching unit is obtained based on the on-off control instruction of the switching unit and the resonant current zero-crossing time reference signal; the switching state of the external excitation inductor is controlled based on the zero-crossing synchronization driving signal of the switching unit, and the resonant cavity topology structure state of the bidirectional LLC converter is determined based on the switching state. The application can reduce the off loss and improve the conversion efficiency.

A power converter includes a transformer, a resonant circuit, a switch circuit, a resonant adjustment circuit, and a controller. The transformer includes a primary-side winding, a secondary-side winding, and a magnetizing inductance. The resonant circuit includes a first resonant capacitor, and the switch circuit includes a first switch and a second switch. The resonant adjustment circuit is coupled to the first resonant capacitor, and the controller is coupled to the resonant adjustment circuit. The controller controls the resonant adjustment circuit to adjust a resonant current flowing through the first resonant capacitor according to an output voltage of the power converter so as to adjust a current value that when the resonant current and a magnetizing current flowing through the magnetizing inductance intersect to be substantially equal to a predetermined value.

Disclosed in the present invention are a three-phase single-stage alternating current-direct current converter, and a control method and apparatus therefor, which are used for improving the conversion efficiency and power density of alternating current-direct current converters. Said converter comprises a three-phase matrix switch circuit, a resonant circuit, an isolation circuit and a rectification circuit. The three-phase matrix switch circuit is connected to three-phase alternating current, and comprises three independently arranged switch branches; each switch branch comprises an upper bridge arm and a lower bridge arm, a midpoint of the upper bridge arm and the lower bridge arm in each switch branch being connected to one-phase alternating current input, and each bridge arm comprising a bidirectional switch assembly or two switch assemblies connected in reverse series. The resonant circuit comprises a resonant capacitor, a resonant inductor and an excitation inductor connected in series, and is connected between a common endpoint of the upper bridge arms and a common endpoint of the lower bridge arms of the three switch branches. The isolation circuit has one side connected to the resonant circuit, and one side connected to the rectification circuit; the rectification circuit comprises at least two switch assemblies, an input side of which is connected to the isolation circuit, and an output side of which is connected to a load device.

The application discloses a kind of MPC prediction control and electricity purchase cost optimization method of photovoltaic hydrogen production system, belong to photovoltaic hydrogen production technical field, in system, the output direct current of photovoltaic system through booster converter and full bridge circuit, first excitation inductance is connected with first winding;The output direct current of grid after rectifier and full bridge circuit, second excitation inductance is connected with second winding;The output direct current of fuel cell through booster converter and full bridge circuit, third excitation inductance is connected with third winding;The output direct current of electrolytic tank through step-down converter and full bridge circuit, fourth excitation inductance is connected with fourth winding;Hydrogen storage tank connects electrolytic tank and fuel cell;Based on system, in electrolytic tank converter, join MPC prediction control algorithm and carry out Z-score function calculation optimal electricity purchase time when system purchases electricity from power grid.The application realizes the optimization of system hydrogen production efficiency, hydrogen production amount and system cost.

The application provides a three-phase LLC resonant converter with an ultra-wide voltage regulating range, comprising a DC input power supply, seven power switching tubes, three resonant inductors, three resonant capacitors, three transformers and their three equivalent excitation inductors, twelve rectifier diodes and an output filter capacitor; the seven power switching tubes form a three-phase bridge inverter circuit; the three resonant inductors, the resonant capacitors and the excitation inductors form three-phase resonant tanks which are connected in a triangle; the three secondary winding of the three transformers are connected to three series H-bridge rectifiers formed by the twelve diodes, and then are connected in parallel with the output filter capacitor and the load; the application has the advantages of providing a three-phase LLC resonant converter with the advantages of large power, high efficiency, narrow working frequency range, ultra-wide output voltage range, ultra-small output current ripple and ultra-small standby power loss, and is widely applied to electric vehicle charging piles and other charging power supplies which require large power and ultra-wide output voltage range.

The application provides a parameter design method of a resonant converter, comprising: determining a loss and magnetizing inductance curve of the resonant converter based on a zero-voltage switching requirement of a primary side switching device of the resonant converter and a zero-current switching requirement of a secondary side switching device, wherein the loss comprises a switching loss and an on-state loss; and determining a magnetizing inductance design value meeting an efficiency optimal condition based on the loss and magnetizing inductance curve of the resonant converter.

According to the bipolar half-bridge direct-current converter for fault topology reconstruction and the control method thereof, the two input ends of an inverter circuit are connected with the positive electrode and the negative electrode of input voltage respectively, the two output ends of the inverter circuit are connected with the two ends of a primary winding of a high-frequency transformer Tr respectively, and the two ends of the primary winding are connected with a first excitation inductor in parallel; a dotted terminal of a secondary winding of the high-frequency transformer Tr passes through a leakage inductor Lk and then is connected with a midpoint of a first bridge arm of the half-bridge three-level bipolar output circuit, and a synonym terminal of the secondary winding of the high-frequency transformer Tr passes through a clamping capacitor Cs and then is connected with a midpoint of a second bridge arm of the half-bridge three-level bipolar output circuit. And two ends of the secondary winding are connected in parallel with the second excitation inductor. Bidirectional power flow is realized while the number of the switching tubes is prevented from being increased, and the power supply reliability is improved.

The invention relates to the technical field of circuit system analysis, in particular to a method, a system and equipment for measuring parameters of a transformer. An excitation current source is applied to the primary side of a to-be-measured transformer, an open circuit of the secondary side is kept, the alternating voltage of the secondary side is measured, the real part and the imaginary part of the ratio of the alternating voltage of a secondary side winding to the alternating input current of a primary side winding are calculated, and the excitation resistance and the excitation inductance of a magnetic core are obtained according to the real part and the imaginary part. Stopping applying excitation, measuring port resistance and inductance from a primary side port, and calculating primary side leakage resistance and leakage inductance in combination with obtained excitation parameters; and opening the primary side, measuring the port resistance and inductance from the secondary side port, and calculating the secondary side leakage resistance and leakage inductance in combination with excitation parameters. The testing method is easy and convenient to operate, the calculation process is simplified, and the parameter measuring precision of the transformer is effectively improved.

Systems and methods for determining the health of a transformer are provided herein. A system includes a transformer, a capacitor, and control circuitry configured to discharge the capacitor across the transformer, measure a voltage across the capacitor, and determine a health of the transformer based on the measured voltage. In some embodiments, a magnetizing inductance of the transformer is determined based on the measured voltage, and the health of the transformer is determined by comparing the determined magnetizing inductance to a reference value. In some embodiments, the transformer is part of a dual active bridge (DAB) converter, and the DAB converter is controlled based on the health of the transformer.

The utility model discloses a magnetic integrated transformer which is formed by integrating a voltage transformation unit and an inductance unit, and a base is fixedly arranged at the bottom of the voltage transformation unit and the bottom of the inductance unit. The voltage transformation unit comprises a plurality of first magnetic core elements and first edge magnetic elements, the first magnetic core elements are sequentially connected end to end to form a first frame, a first mounting space is formed between every two first magnetic core elements, and a voltage transformation unit magnetic core is arranged in each first mounting space; the first edge magnetic element is connected to the top of the first frame; the transformer is formed by integrating a plurality of transformation units and inductance units, and when the transformation units and the inductance units are formed, a common surface is arranged for magnetic core elements, so that the volume and the weight of the inherited transformer are reduced, and the efficiency and the power density of the integrated transformer are improved; the size of the air gap between the magnetic core and the magnetic column in the transformer is set to be an adjustable structure, so that required excitation inductance and resonance inductance can be obtained through adjustment.

The present application discloses the rotor structure and application of an asynchronous start permanent magnet synchronous motor. The conductive bars are distributed unevenly and asymmetrically as a whole. The conductive bars and permanent magnets together form a multi-layer rotor structure with a magnetic flux barrier function. The conductive bars are tilted in the direction of the motor's main magnetic flux, which significantly increases the d-axis magnetic resistance, reduces the d-axis magnetizing inductance, increases the motor's salient pole ratio, increases the magnetic resistance torque, increases the acceleration torque during the pull-in synchronization process, and strengthens the pull-in synchronization capability. When the number of conductive bars is the same as in the related art, the conductive bar cross-sectional area in the back-electromotive force direction is larger, the overall conductive bar resistance is reduced, the slip rate near the critical synchronous speed is reduced, and the pull-in synchronization capability is improved. In addition, the conductive bars in the direction of the motor's main magnetic flux have a certain spatial tilt angle, which causes significant changes in the d- and q-axis currents, reduces the d-axis inductance, increases the d-axis current, and reduces the q-axis current, resulting in a smaller composite current, a larger internal power factor angle, and a smaller power factor angle, thereby improving both the power factor and efficiency.

The invention belongs to the technical field of power electronics, and discloses a wide-range zero-reactive LLC resonant converter based on a fractional order capacitor structure, which comprises a DC input voltage, an H-type inverter bridge consisting of Q1-Q4, a resonant inductor Lr, a resonant capacitor Cr and a resonant cavity structure consisting of an excitation inductor Lm, energy is transmitted to a secondary side through a transformation ratio N: 1 of a transformer, and the energy is transmitted to a secondary side through the resonant cavity structure. D1-D4 form a full-bridge rectifier which is connected with the secondary side of the transformer and is finally connected with a filter capacitor Cb and a load R, and the most important passive fractional order capacitor structure PFOC is connected in series into the resonant cavity structure. According to the invention, the inversion voltage in the passive fractional order circuit and the inversion voltage of the main circuit are controlled to be kept lagging by 90 degrees, so that the inversion voltage in the resonant cavity and the resonant cavity current realize a zero phase angle ZPA. When the ZPA is realized, the voltage gain of the LLC resonant converter is determined by the frequency, the frequency is inversely proportional to the voltage gain, and the voltage gain is less limited by the frequency.

The application provides a kind of multi-phase LLC-based direct current converter model prediction device and control method, specifically relates to direct current converter energy conversion technical field.The device includes two-stage converter cascade, input port has S, output port has N.The front stage is composed of S Buck circuits in parallel, each Buck circuit contains an inductor and two MOS tubes;The back stage is composed of N-phase LLC resonant converter, connected with the output port of the front stage Buck circuit.The front bridge of N-phase LLC resonant converter adopts half-bridge circuit, including two MOS tubes, resonant inductor, resonant capacitor and excitation inductor.The device adopts model prediction control method, the output voltage of next cycle is predicted to adjust relevant variables to maintain the purpose of output voltage.The application can access multiple voltage levels, model prediction control can be performed on direct current converter, voltage of specified voltage level can be output, voltage output can be effectively adjusted, and the demand of multi-scene application can be met.

This invention discloses an LLC resonant converter with a wide voltage range input, belonging to the field of power electronics technology, including a DC voltage source V. in First bus voltage divider capacitor C in1 Second bus voltage divider capacitor C in2 First full-bridge switch Q1, second full-bridge switch Q2, third full-bridge switch Q3, fourth full-bridge switch Q4, first bidirectional switch Q5, second bidirectional switch Q6, first resonant inductor L r1 Second resonant inductor L r2 First resonant capacitor C r1 Second resonant capacitor C r2 First excitation inductor L m1 Second excitation inductor L m2 Transformer TR1, Transformer TR2, First rectifier diode D7, Second rectifier diode D8, Third rectifier diode D9, Fourth rectifier diode D 10 Output filter capacitor C o And load R. This invention can effectively eliminate the situation of instantaneous input voltage instability without increasing the complexity of the main control circuit, and ensure the normal operation of downstream electrical equipment.