82results about How to "Reduce conduction loss" patented technology

The invention belongs to the technical field of crystal growth, and provides a low-resistivity silicon carbide single crystal growth method and system and a single crystal, silicon carbide powder is uniformly paved at the bottom of a graphite crucible, metal carbide material particles are uniformly paved on the surface of the silicon carbide powder, and silicon carbide seed crystals are adhered to the top of the graphite crucible; the graphite crucible is sealed, and the interior of the graphite crucible is vacuumized; heating the graphite crucible subjected to vacuumizing treatment, filling carrier gas into the graphite crucible, then slowly replacing the carrier gas with doped source gas, slowly increasing the growth pressure to a set pressure, and growing a buffer layer; after the growth of the buffer layer is completed, changing the growth condition to grow the heavily doped silicon carbide single crystal; and after the growth of the crystal is completed, cooling the graphite crucible subjected to vacuumizing treatment, so that the crystal is naturally cooled, and the low-resistivity silicon carbide single crystal is obtained. The doping concentration of the silicon carbide single crystal can be improved, and the resistivity of the silicon carbide material can be reduced.

The invention discloses a planar gate dual-control electrode 4H-SiC composite transistor structure which comprises a plurality of cell structures connected in parallel, each cell structure comprises an n buffer layer on a 4H-SiC n + substrate, an n-drift region, an n carrier expansion layer and p body regions in the two sides of the n carrier expansion layer, each p body region is of a mesa structure, an n + source region and a p + region are arranged in the upper part and the lower part, and a gap is formed between the n + source region and the p + region; gate oxide layers and polycrystalline silicon layers are arranged on the surfaces of the n carrier expansion layer, the p body regions on the two sides and part of the n + source region; a plane grid G is arranged on the surface of the polycrystalline silicon layer; a source S is arranged on the surface of the n + source region; a base B is arranged on the surface of the p + region; a drain electrode D is arranged on the back surface of the 4H-SiC n + substrate; the cellular structure is in bilateral symmetry with the planar grid G as the axis, equivalently, the VDMOS and the BJT are connected in parallel, the VDMOS is located in the center, and the BJT is located on the outer side. According to the invention, the conduction loss of the device can be reduced, the anti-short-circuit capability is improved, and the influence of a body diode is eliminated.

The invention provides a modulation mode switching synchronous rectification soft switching buck type constant voltage power supply which comprises an input filter circuit, a power inductor L1, an output filter circuit, a main switch tube Q1, a synchronous rectification tube Q2 and a control circuit. The left end of the power inductor L1 is connected to the source electrode of the main switch tube Q1 and the drain electrode of the synchronous rectifier tube Q2, the right end of the power inductor L1 is connected to the positive electrode of the output capacitor, the drain electrode of the main switch tube Q1 is connected to the positive electrode of the input capacitor, and the source electrode of the synchronous rectifier tube Q2 is connected to a reference ground through a power inductor current sampling resistor RS1; and the control circuit respectively controls the on-off states of the main switch tube Q1 and the synchronous rectifier tube Q2 so as to realize zero-voltage conduction of the synchronous rectifier tube Q2. Through the characteristics of different modulation modes, light-load and heavy-load modulation mode switching and synchronous rectifier tube soft switching are realized, and the loss of the switching power supply under different conditions is reduced.

The invention provides a driving circuit, a motor driving chip, a motor control device and electric equipment. The driving circuit comprises a power device unit and a power device driving circuit, wherein the power device unit comprises a first silicon-based power device, a first silicon carbide power device, a second silicon-based power device and a second silicon carbide power device; the power device driving circuit is used for driving the first silicon carbide power device to be switched on in a switch-on stage and a switch-off stage of the power device unit and driving the first silicon-based power device to be switched on in the switch-on stage of the power device unit when the power device unit is used as an output loop of a power signal; and when the power device unit is used as an input loop of a power signal, the second silicon carbide power device is driven to be switched on in the switching-on stage and the switching-off stage of the power device unit, and the second silicon-based power device is driven to be switched on in the switching-on stage of the power device unit. The driving circuit can reduce the switching loss of the power device and prolong the service life of the power device.

The application provides an inverse-conducting insulated gate bipolar transistor and a preparation method thereof, and belongs to the technical field of power semiconductor devices, and comprises: a first groove is a gate groove, a second groove is an emitter groove, and a third groove is an ineffective gate groove; in the lateral direction parallel to the cell surface, the first groove, the second groove and the third groove are sequentially and spacedly arranged, and the first groove and the second groove are connected through a fourth groove, and the fourth groove is a gate groove; in the longitudinal direction, the second groove is located between two adjacent fourth grooves. The beneficial effects are as follows: the gate groove and the ineffective gate groove are connected through the lateral gate groove, the forward conduction voltage drop and the conduction loss of the device are reduced; the current channel is increased, the current distribution is more uniform, the heat loss is reduced, the reliability and the power density of the device are improved; the emitter groove is used for repeatedly arranging the polysilicon gate and the metal gate in the lateral and longitudinal directions, the regularly arranged diodes and Schottky diodes are formed, and the reverse diode current distribution is more uniform.

The application discloses a kind of modular multilevel converter thermal balance control method and system based on dynamic retention factor, for the thermal imbalance problem of flexible direct current transmission modular multilevel converter, propose thermal-electricity collaborative control method based on dynamic retention factor (DRF), break through the limitation of traditional capacitor voltage balancing strategy.Capacitor voltage tolerance boundary (rated value ±5%~10%) is set, combined with real-time temperature feedback to build dynamic weight adjustment mechanism, collect IGBT junction temperature to calculate normalized temperature deviation value, generate dynamic retention coefficient, and then obtain the corrected capacitor voltage, in charging mode, low-temperature module is preferentially put into in ascending order, in discharging mode, high-temperature module is preferentially put into in descending order;Further integrate model predictive control (MPC), based on thermal model rolling solution minimization temperature difference objective function, adjust dynamic adjustment coefficient ΔK.The scheme can effectively solve the problem of small-capacitor module thermal fatigue early decline, provide high reliability technical support for high-voltage high-power new energy grid-connected equipment.

The application discloses a totem pole power factor correction circuit, a control method, a device and equipment, the circuit includes a rectifier module, a reactor, a capacitor module, a control module and a switching module, the input end of the rectifier module is connected with an alternating current power supply, and the output end of the rectifier module is used for being connected with a load; the capacitor module is connected with the output end, and includes a first capacitor and a second capacitor in series connection, and the first connection point of the first capacitor and the second capacitor is connected with the alternating current power supply through the switching module; by setting the control module, the rectifier module and the switching module can be controlled according to load parameters, so that the totem pole power factor correction circuit is switched to a synchronous rectification mode or a non-controlled rectification mode, so that the totem pole power factor correction circuit can reduce loss and save resources under the condition that load parameters change, and the circuit efficiency is ensured. The application can be widely applied in the technical field of control.

The invention provides a PSR flyback conversion circuit, a constant current control method and a power system.The circuit comprises a primary winding circuit, a secondary winding circuit and an auxiliary winding circuit, and the auxiliary winding circuit is a voltage sensing loop used for PSR; the switch tube control unit of the primary winding circuit is configured as follows: when the voltage of the second end of the power switch tube of the primary winding circuit is greater than or equal to a constant current reference voltage, the circuit enters a constant current output mode; and when the circuit enters the constant current output mode, at least setting an excitation reset time ratio based on a first voltage value sensed by the auxiliary winding circuit, the set excitation reset time ratio being greater than or equal to 0.5. Therefore, when the input voltage is far larger than the output reflection voltage N * Vo, it is guaranteed that the secondary winding circuit can output the correspondingly set constant current, the primary and secondary RMS current of the PSR flyback conversion circuit is reduced by increasing the excitation reset time ratio, and then the conduction loss is reduced, and the efficiency is improved.

The application provides a semiconductor device manufacturing method and a semiconductor device. The method comprises the following steps: providing a semiconductor substrate, a first trench is formed in the semiconductor substrate, a field oxide layer is formed on the side wall and the bottom wall of the first trench, so that a space outside the surface of the field oxide layer in the first trench forms a second trench, and the first conductive material is filled in the second trench. The field oxide layer of the side wall of the first trench is removed to a first set depth to form a third trench. A barrier layer is formed on the bottom wall of the third trench, a gate oxide layer is formed on the side wall of the third trench, at least two separated gates are formed in the space outside the surface of the gate oxide layer in the third trench, the barrier layer is removed, and the gap between the separated gates is filled. Then, the space between the bottom of the separated gate and the upper surface of the field oxide layer forms an air layer. Due to the introduction of the air layer, the gate leakage capacitance and the gate-source capacitance are reduced, the switching loss and the conduction loss are reduced, and the opening rate of the device is improved.

The application relates to the technical field of ocean exploration measurement, and discloses a Doppler log power supply control method and system based on hierarchical intelligent control, which comprises the following steps: acquiring and adaptively filtering original electrical and environmental signals by using a multi-parameter dynamic detection module; performing integration autoregressive moving average model identification based on load current sampling data by using a load adaptive adjustment module, and outputting predicted load current values; combining the prediction results to generate a feedforward instruction, so as to adjust the target switching frequency, duty cycle and working mode of a direct-current-to-direct-current conversion circuit; and using a stability verification layer to evaluate control loop indexes in real time based on a linear periodic time-varying Nyquist criterion, and sending an instruction change control parameter or a warning threshold at an instability critical point. The application improves the power conversion efficiency and dynamic response lag problem under a variable load environment, and improves the anti-disturbance capability and operation reliability of a Doppler log power supply system.

This application discloses a low-power underwater acoustic communication system for underwater navigation and ranging, relating to the field of underwater communication technology. It includes a digital signal processing platform for preprocessing the digital baseband signal to be transmitted to obtain a single-ended analog signal; a transmitting circuit module, comprising at least: a power amplification unit; the power amplification unit being a single chip integrating a PWM modulation circuit, a drive amplification circuit, and a power amplification circuit, wherein the power amplification unit sequentially performs PWM modulation, drive amplification, and power amplification on the single-ended analog signal to output a target amplified signal; and an underwater acoustic transducer for converting the target amplified signal into an acoustic signal and transmitting it into the water medium. This application can reduce energy loss during signal transmission.

The application discloses a resonant converter control method and device based on threshold voltage control, and the method comprises the following steps: comparing an input voltage with a primary side equivalent voltage to determine whether the resonant converter is currently working in a boost mode or a buck mode; determining threshold voltages of a resonant capacitor in the boost mode and the buck mode; comparing the threshold voltages with collected resonant capacitor voltages to determine switching signals of an inverter circuit; and the threshold voltages of the resonant capacitor in the boost mode and the buck mode are calculated based on P-stage cosine response parameters and N-stage cosine response parameters of the resonant capacitor voltages. By using the above technical scheme, the resonant converter has strong voltage ripple suppression capability, effectively suppresses secondary harmonic voltage ripples from a previous stage, and the control signals are directly determined by input and output states, thereby having excellent dynamic performance.

The invention discloses a single-stage isolated bidirectional AC-DC converter and a control method thereof, and belongs to the technical field of power electronic converters, the single-stage isolated bidirectional AC-DC converter comprises a primary side conversion module, a voltage transformation module and a secondary side conversion module, and the primary side conversion module, the voltage transformation module and the secondary side conversion module are connected in sequence. The single-stage isolation type bidirectional AC-DC converter provided by the invention has the advantages of smaller conduction loss, lower cost and higher power density.

The invention discloses a resonant dual-active bridge converter and a control method, and the converter comprises a primary full-bridge circuit, a secondary full-bridge or half-bridge circuit, a transformer, and an LC resonant network composed of a resonant inductor and a resonant capacitor which are connected in series. The control method comprises the following steps: acquiring parameters of an input voltage V1, an output voltage V2, a transmission power P, a transformer turn ratio N, a resonant inductance Lm and a resonant capacitance Cr of the converter; and calculating a primary fundamental wave equivalent voltage and a secondary fundamental wave equivalent voltage, and calculating an inner phase shift angle alpha between a first bridge arm and a second bridge arm in the primary full-bridge circuit through the primary fundamental wave equivalent voltage and the secondary fundamental wave equivalent voltage. The LLC converter has the beneficial effects that the inherent defects that the gain range of a traditional LLC converter is narrow (generally only 0.8-1.2) and the circulating current is sharply increased and the efficiency is sharply reduced when the voltage is seriously mismatched in the traditional phase-shifting DAB are fundamentally overcome.

The application discloses a Sepic type power correction circuit based on a switched inductor, which comprises switching tubes S1-S3, diodes D1-D5, inductors L1-L5, capacitors C1 and C o The diodes D3-D5 and the inductors L4 and L5 form a switched inductor structure, and the voltage gain of the converter is D / (2-D). Compared with a conventional Sepic PFC converter, the Sepic type power correction circuit based on the switched inductor improves the step-down gain, ensures that the whole duty cycle range is in a step-down state, and has a larger duty cycle than the conventional Sepic PFC converter in the case of a high step-down ratio, thereby effectively avoiding the emergence of a limit duty cycle. The no-bridge structure can realize lower conduction loss. The original output diode is replaced by the switched inductor structure, so that the output current is continuous, and the output current can be filtered. All the switching tubes are common ground, and a lower-cost driving circuit can be used.

The utility model relates to a quick charge adapter circuit, including transformation circuit and synchronous rectification circuit, transformation circuit includes transformer T1, transformer T1 includes first secondary side coil and second secondary side coil, the first end of second secondary side coil is used as the positive pole of direct current power supply VOUT2, synchronous rectification circuit includes NMOS transistor Q1 and rectification controller U4, the second end of second secondary side coil is used as the positive pole of direct current power supply VOUT2. The drain electrode of the NMOS tube Q1 is connected with the second end of the second secondary side coil, and the grid electrode of the NMOS tube Q1 is connected with the control end of the rectification controller U4; the power output end of the rectification controller U4 is connected with the first end of the first secondary side coil, the speed setting end of the rectification controller U4 is grounded through a resistor R75, and the monitoring end of the rectification controller U4 is connected with the drain electrode of the NMOS tube Q1 through a resistor R74. Compared with traditional diode rectification, the synchronous rectification circuit reduces conduction loss and improves rectification efficiency.

The present invention discloses a multi-phase winding of a permanent magnet motor stator. In the multi-phase winding, each phase winding is formed by connecting one coil or multiple coils, each coil includes a double-layer conductor element at the head end and a single-layer conductor element at the end and a plurality of intermediate double-layer conductor elements arranged between the two. The upper (or lower) conductors of all double-layer conductor elements are connected in sequence through the end conductors, and after being connected to the end element, the lower (or upper) conductors of all double-layer conductor elements are connected in reverse order. Each element corresponds to a stator slot, and there is an insulating medium between the upper and lower conductors of the double-layer conductor elements located in the same stator slot, and the number of stator slots spanned by adjacent elements in the same coil is the same. The winding of the present invention has the advantages of small leakage reactance, small conductive resistance, small heat loss, etc., which is of great significance to improving the power factor, efficiency and power density of the motor. The coil topology can be extended and expanded according to the number of stator slots, and the present invention is particularly suitable for multi-pole and multi-phase permanent magnet motors.

The application discloses a bridgeless Cuk PFC converter based on a switched-inductor-capacitor structure, which comprises switching tubes S1-S3, diodes D1-D4, inductors L1-L5, capacitors C1, C2 and C o The diodes D3 and D4, the capacitor C2 and the inductors L3 and L4 form a switched-inductor-capacitor structure. The original freewheeling diode is replaced by the switched-inductor-capacitor structure, so that the voltage gain of the converter is D / 2(1-D), compared with a traditional Cuk PFC converter, the converter realizes positive voltage output and improves the voltage reduction gain, and the duty cycle range in the voltage reduction mode is wider. Meanwhile, the bridgeless structure is adopted, so that lower on-state loss can be realized. The converter has continuous input and output currents, high power factor and high efficiency, and has rich application.

The application belongs to the field of solid-state lithium battery materials, and provides a polymer-based solid-state electrolyte film, a preparation method and application thereof, and the application forms a crosslinked shell layer formed by polyvinyl alcohol, polyethylene glycol diglycidyl ether, boric acid and lithium hydroxide monohydrate outside a polyvinylidene fluoride-hexafluoropropylene copolymer core microsphere, and is dry-mixed and hot-pressed into a film with lithium bisfluorosulfonylimide to form a core-shell composite microsphere conduction and support system, so that the film body maintains the processability while taking into account the chain segment movement, structure constraint and residual solvent control, solves the problem that the mechanical strength and ion conduction, the processing fluidity and the electrochemical stability are difficult to be considered, and is suitable for a full solid-state lithium secondary battery.

The utility model relates to a kind of integrated pump valve drive's electronic controller powered by 48V, it is related to the field of automotive electronics, and electronic controller is equipped with 48V direct current total power input end, and electronic controller includes: pump motor drive module, connects 48V direct current total power input end;First DCDC step-down circuit one, connects 48V direct current total power input end, and output end outputs medium voltage power supply one;Solenoid valve drive module, connects medium voltage power supply one;Second DCDC step-down circuit, connects 48V direct current total power input end, and output end outputs medium voltage power supply two;Second low voltage supply circuit, connects medium voltage power supply two, and output end outputs low voltage supply;Microcontroller module, connects low voltage supply, and control signal connects pump motor drive module and solenoid valve drive module;Communication interface module, with microcontroller module two-way signal connection.The utility model realizes 48V power supply under high-power pump motor drive efficiency and multi-channel solenoid valve comprehensive optimization by differentiating power architecture.

The application discloses a three-level full-bridge dual active bridge converter and a midpoint potential balance control method. The converter comprises a high-frequency transformer, a DC input voltage source is arranged on the primary side of the high-frequency transformer, and series-connected upper and lower capacitors are connected between the positive and negative electrodes of the DC input voltage source. Three-level half-bridge A and three-level half-bridge B are connected in parallel, a node between the upper and lower capacitors is connected to the midpoint of two clamping diodes of the two three-level half-bridges, the center point of the three-level half-bridge A is connected to one end of the primary side of the high-frequency transformer through a power transmission inductor, and the center point of the three-level half-bridge A is connected to the other end of the primary side of the high-frequency transformer through a DC isolation capacitor. In the control method, the primary side power device is divided into a fixed 50% duty ratio basic bridge arm and a non-symmetrical duty ratio adjusting bridge arm, a PI voltage balance loop is constructed by taking the voltage difference of the two capacitors as feedback, the duty ratio of the adjusting bridge arm is dynamically adjusted, the average value of the midpoint current is changed, and the midpoint potential balance is realized.

This invention relates to the field of electronic circuit technology and provides a method and apparatus for dynamically adjusting the dead time of a full-bridge circuit. The method includes: acquiring the current of each arm of the full-bridge circuit; for any arm, determining one MOSFET as the driving transistor and the other as the freewheeling transistor based on the direction of the current; if the driving transistor is on and the freewheeling transistor is off, then after controlling the driving transistor to turn off, determining the peak current based on the current of the driving transistor during its on-time, and controlling the freewheeling transistor to turn on when the current is less than the peak current. This invention solves the problem that existing dead time setting methods are difficult to dynamically optimize and adjust, and cannot adapt to real-time changes in operating conditions.

The invention discloses a bridge arm compensation modulation method suitable for a bridge arm multiplexing type modular multi-level high-voltage direct-current converter, and belongs to the technical field of high-voltage direct-current power transmission. The method comprises the following steps: firstly, generating respective quasi square wave reference voltage waveforms and quasi square wave reference current waveforms of a high-voltage bridge arm, a low-voltage bridge arm and a multiplexing bridge arm, then obtaining respective actual voltage reference values of the high-voltage bridge arm, the low-voltage bridge arm and the multiplexing bridge arm, then cooperatively adjusting the voltage of each bridge arm, generating a switching control instruction of each sub-module in each bridge arm, and finally switching the sub-modules in each bridge arm. And controlling the bridge arm current to complete quasi square wave commutation within a preset transition time, and completing bridge arm compensation modulation of the converter. The power transmission capacity, the dynamic response and the waveform quality are remarkably improved, meanwhile, the device is easily integrated into an existing bridge arm multiplexing type modular multi-level high-voltage direct-current converter, and the device is suitable for interconnection scenes of different direct-current voltage levels in a high-voltage direct-current power grid.

The invention provides a novel RC-IGBT structure with a hole circulation path and a good compromise relationship, which comprises a device main body, collector metal is arranged at the bottom of the device main body, a p + collector region, an FS layer, an n-drift region, a groove with a grid electrode at the top, an n + emitter region, a p + contact region and a p base region are sequentially arranged upwards, a second CS storage layer is arranged at the bottom, and the emitter composite structure on the two sides comprises a deep p-type region, a deeper p-type region, a hole channel and a CS storage layer. Through the above structure, the deep p-type region and the deeper p-type region optimize the electric field distribution, improve the doping concentration of the CS layer, enhance the hole accumulation effect, reduce the conduction voltage drop, accelerate the carrier export during the turn-off of a hole channel, and shorten the turn-off time, and at the same time, under the short-circuit working condition, the structures cooperatively export holes, weaken the conductivity modulation effect, improve the short-circuit endurance capability, and improve the performance of the device. And finally, good balance of voltage resistance, conduction voltage drop and switching speed is realized, and the comprehensive performance of the device is remarkably improved.

The invention discloses a semiconductor device and a preparation method thereof, and belongs to the technical field of semiconductors. The semiconductor device comprises a semiconductor body, a first electrode, a second electrode, a first ferroelectric material layer and / or a second ferroelectric material layer. The first electrode is arranged on the first surface of the semiconductor body, the second electrode is arranged on the second surface of the semiconductor body, the first ferroelectric material layer is arranged on the side, away from the semiconductor body, of the first electrode, and / or the second ferroelectric material layer is arranged on the side, away from the semiconductor body, of the second electrode. According to the technical scheme, the device structure is optimized, so that the switching speed of the device is improved, and power consumption is reduced.

The invention provides a control method, system and device of a resonance-based isolated active bridge converter and a medium. The system comprises a primary side circuit module, an L-C series resonant cavity, a high-frequency transformer and a secondary side circuit module. The method comprises the following steps of: sampling primary and secondary voltage and current, calculating voltage gain, and solving threshold current of primary and secondary switching tubes for realizing zero voltage switching (ZVS) in combination with junction capacitance and dead time; geometric constraints of resonance current and capacitor voltage are established based on phase plane analysis, the proportions of a primary side inner phase shift angle, a secondary side inner phase shift angle and an outer phase shift angle relative to a resonance period are solved in a unified mode, and then the switching frequency is determined; and converting to obtain an actual phase shift angle and generating a gate pole driving signal, thereby realizing full-working-condition ZVS of the primary and secondary side devices. The soft switching boundary is accurately given in the wide voltage gain and wide load range, the peak value and the effective value of the resonance current are remarkably reduced, the conduction and switching loss are considered, the circulation is suppressed, and the efficiency and the power density are improved.

This invention provides a high UIS reliability planar gate silicon carbide VDMOS, comprising: a drift layer connected to a silicon carbide substrate; a gate protection zone and a shunt region within the drift layer, the gate protection zone being connected to the shunt region; a protrusion on the drift layer; a source protection zone connected to the drift layer and the protrusion; a grounded source protection zone; a P-type well region connected to the source protection zone and the protrusion; an N-type source region and a P-type source region on the P-type well region, the N-type source region being connected to the P-type source region and the P-type well region; a lower side of an insulating dielectric layer connected to the P-type well region and the protrusion; a lower side of a gate metal layer connected to the upper side of the insulating dielectric layer; source metal layers connected to the P-type source region and the N-type source region respectively; and a drain metal layer connected to the lower side of the silicon carbide substrate. The UIS resistance and reliability of the device are improved through the gate protection zone and the grounded source protection zone.

The invention relates to the technical field of battery management, and discloses a battery management system, method and device, a medium and an unmanned aerial vehicle. The active equalization management circuit is electrically connected with the series battery pack and is used for collecting state information of the single batteries and executing bidirectional active equalization control on the series battery pack; the interface unit is used for establishing electric connection with external equipment; wherein the series battery pack and external equipment form a direct connection type main loop through the interface unit, and energy on-off control of the direct connection type main loop is realized through physical plugging of the interface unit. Energy on-off control is realized through physical plugging of the interface unit, an electronic power switch device is prevented from being arranged in a main loop, the design of the main loop is effectively simplified, and hardware complexity and control difficulty are reduced. And a direct connection type main loop is formed by the series battery pack and the external equipment, so that the number of intermediate devices in the main loop is reduced, the conduction loss is effectively reduced, and the energy transmission efficiency is improved.

A three-level double-buck conversion circuit for a post-stage of an energy storage inverter integrated device, comprising an energy storage battery, a bidirectional DC-DC converter, switching tubes S1, S2, S3, S4, S5, S6, S7, diodes D1, D2, D3, D4, D5, D6, D7, inductors L1 and L2, and capacitors C1 and C2. The three-level double-buck conversion circuit comprises a bidirectional switching tube composed of switching tube S4, diodes D3, D4, D5, and D6, and a double-buck circuit structure composed of switching tubes S2 and S3, diodes D1 and D2, and inductors L1 and L2. The three-level double-buck conversion circuit of the present application organically integrates three-level technology and a double-buck circuit structure, and has the advantages of low switching tube voltage stress, high reliability, and high efficiency.

The utility model discloses a modularized purification system which comprises a shell, a fan is arranged on the right side in the shell, two openings are formed in the top of the fan, one opening is that an air inlet is connected with an air outlet hole of a glove box operation table through a pipeline, and the other opening is that an air outlet is communicated with a purification column on the north side in a box body through a pipeline. The purification column is communicated with the solvent column through a pipeline, and the solvent column is connected with an air inlet of a glove box operation table through another pipeline. Compared with the prior art, the device has the characteristics of small size, difficulty in leakage, convenience in control, convenience in reduction of energy conduction loss and the like.