Short circuit detection and protection method and device for multiple IGBTs (insulated gate bipolar transistors)

The invention discloses a short circuit detection and protection method and device for multiple IGBTs (insulated gate bipolar transistors). The method comprises the steps of 1, sending a drive pulse to each IGBT, receiving the drive pulse by the IGBT and driving the IGBT to be on; 2, detecting voltage values at two ends of each IGBT in real time, judging whether the voltages values are larger than a preset short-circuit voltage threshold value, if yes, judging that the interior of the IGBT is in an open circuit fault state, and sending a judgment result; 3, converting the detected short circuit voltage into a short circuit current value, computing the target multiple of the short circuit voltage and the short circuit current, judging whether the target multiple is larger than a preset multiple threshold value, if yes, reducing the drive pulse to a negative level, and driving the IGBT to be switched off. The device comprises a plurality of short-circuit detection protection modules which ...

Method for analyzing nitrosamine precursor by using solid-phase extraction cartridges with different polarities

The invention discloses a method for analyzing a nitrosamine precursor by using solid-phase extraction cartridges with different polarities, and belongs to the field of water supply and drainage. The method is characterized in that chromatographic pure methanol and pure water are used for cleaning the solid-phase extraction cartridges when basic polarity characteristics of the nitrosamine precursor in water are analyzed; a water sample is filtered through a 0.45 micron filter membrane, and passes through the solid-phase extraction cartridges at constant flow speed of 1.0 to 2.0ml/min, and indexes including generation potential and the like of the nitrosamine in inflow and effluent are tested respectively; when nonpolar octoalkane solid-phase extraction cartridge (called C18 for short) is selected, polar and nonpolar nitrosamine precursor concentration distribution information can be obtained; when a strong cation exchange resin solid-phase extraction cartridge (called SCX for short) is ...

Hermetic seal terminator

Grade-changing, pressure-regulating and online-grinding device for slip ring and using method for grade-changing, pressure-regulating and online-grinding device

The invention relates to a grade-changing, pressure-regulating and online-grinding device for a slip ring and a using method for the grade-changing, pressure-regulating and online-grinding device. The device comprises a fixed snap ring, a movable snap ring, a clamping bolt, a grinding block cabin, a grinding block, a connecting bolt, a fixing hinge pin, an extension spring, a pressing arm, a rotating hinge pin, a support and an insulator pressing block, wherein the fixed snap ring and the movable snap ring are combined to form a ring structure; the fixed snap ring and the grinding block cabin are fixed together; the grinding block is arranged in the grinding block cabin; the pressing arm can rotate around the rotating hinge pin; and the insulator pressing block presses the grinding block on the surface of the slip ring under the action of the extension spring. The using method mainly comprises the following steps of mapping; selecting the grinding block and the extension spring; mounting ...

A analog voltage current output circuit for driving a vehicle converter

The utility model discloses an analog voltage current output circuit for driving a vehicle converter, including connect gradually be used for exporting the PWM ripples little the control unit, be used for converting data signal analog voltage signal's digital analog conversion circuit into and being used for converting analog voltage signal into the voltage conversion current circuit of simulation current signal, still including being used for keeping apart the buffer unit to the data that the data of little the control unit output are kept apart, cushions, data are kept apart the buffer unit and are connected a little between the control unit and the digital analog conversion circuit. The utility model discloses can keep apart, cushion transmitting data between little the control unit and the digital analog conversion circuit, have simple structure, low cost, can realize the data insulation blocking, realize the synchronous advantage of data transmission simultaneously.

Ultralow-temperature vacuum multi-channel combined type dewar

The invention discloses an ultralow-temperature vacuum multi-channel combined type dewar which comprises a dewar flask, wherein the dewar flask is internally provided with an air tightness chamber; the side wall of the dewar flask is provided with a multi-channel radio frequency coaxial air-tight seal adapter and a multi-core low frequency air-tight seal connector which are connected to the inner circuits and outer circuits of the dewar, thus the external ports of the dewar flask are reduced, and the integral leakage rate of the dewar is lowered greatly. According to the business necessities, the multi-channel radio frequency coaxial air-tight seal adapter can be distributed on the side wall of the dewar flask by multiple combination methods, the wire cable layout in the dewar flask can be optimized, and the insertion loss and heat dissipation of the wire cable in the dewar can be lowered; and the difficulty of providing an ultralow temperature and long-term high-vacuum degree pressure ...

Method for reducing disinfection by-products generated from water treatment

The invention discloses a method for reducing disinfection by-products generated from water treatment. The method comprises the following specific steps: adding 0.5-20mg/L of ferrate to to-be-treated water, and stirring for 10-30 minutes at the rotating speed of 200-500r/min, wherein the pH range is 6-12; adding 5-15mg/L of coagulant, stirring for 3-5 minutes at the rotating speed of 150-250r/min, stirring for 10-30 minutes at the speed of 20-60r/min, and standing for 30-60 minutes to precipitate; sucking supernate at the position which is 1-3cm far away from the liquid level after precipitating; and adding a sodium hypochlorite solution to the supernate, and disinfecting, wherein the adding amount of sodium hypochlorite is 3-12.8mg/L. Compared with a conventional process, the method disclosed by the invention has the advantages that the content of the disinfection by-products can be greatly lowered by ferrate preoxidation enhanced coagulation and sodium hypochlorite disinfection under ...

High-capacity alternating-current analog power supply and control method thereof

The invention relates to a high-capacity alternating-current analog power supply and a control method thereof, a topological structure of the high-capacity alternating-current analog power supply is based on a modular design concept, outputs of a plurality of power modules are connected with a plurality of windings on a primary side of an isolation transformer to be indirectly connected in parallel to realize current capacity expansion, and a rated working voltage is reached through boosting of an isolation boosting transformer. According to the system based on the topology, high-voltage large-capacity alternating current output can be conveniently achieved based on the low-voltage power modules, reduction of the rated voltage output by the system is not affected after a bypass quits operation due to the fact that part of the power modules break down, and therefore the system has the advantages of being low in cost and high in reliability.

A screw pump protection device for mud jacking system

The utility model discloses a screw pump protection device for mud jacking system, including interconnect's proximity switch and screw rod pump control system unit, what proximity switch detected the mud jacking system treats whether to remain in the mud jacking container mud jacking liquid to send detected signal to screw rod pump control system unit, screw rod pump control system unit detects signal control according to received and starts, stops the screw pump. The utility model has the advantages of simple structure, low cost, can be at mud jacking in -process protection screw pump by the dry grinding and do not protect the precision high.

Ultralow-temperature vacuum multi-channel combined type dewar

Wide voltage range input redundant power supply

The invention relates to the technical field of power supplies, in particular to a wide voltage range input redundant power supply which comprises a direct current input end, an alternating current input end, an output module, a BUCK control module, a BOOST control module, a rectifier module, a PFC control module and a controller. The direct current input end is connected with the input end of the BUCK control module; the output end of the BUCK control module is connected with the input end of the BOOST control module; the AC input end is connected with the input end of the rectifier module; the output end of the rectifier module is connected with the input end of the PFC control module; the output end of the PFC control module and the output end of the BOOST control module are respectively connected with the input end of the output module; and the BUCK control module, the BOOST control module and the PFC control module are electrically connected with the controller respectively. The direct-current ...

Hermetic seal terminator

The invention discloses a hermetic seal terminator which comprises a flange hermetic seal adapter, a metal pipe and a metal terminating clip, wherein the two ends of the metal pipe are respectively connected to the flange hermetic seal adapter through nuts; one end of the flange hermetic seal adapter is in a slope shape; a barbed bulged part which is inclined downwards is arranged in the middle of the slope; the barbed bulged part is matched with the inner walls of the nuts to form a barbed cavity which is used for filling the extruded metal pipe; and the flange hermetic seal adapter is hermetically connected with the metal pipe. According to the invention, the flange hermetic seal adapter made of different materials does not need to be welded to the metal pipe, thus the air tightness is good; the metal terminating clip is adopted, thus the sealing termination success rate of the metal pipe is high, the leakage rate is low, the production cost of the metal pipe is low, and the problems ...

Low-ripple high-voltage energy storage pulse capacitor charging power supply

The invention relates to a low-ripple high-voltage energy storage pulse capacitor charging power supply, the input of the power supply is three-phase 380V, the output DC voltage is DC10kV-DC100kV, the power supply operates in two quadrants, and the power supply comprises an ACDC module, a voltage sensor, a current sensor HA and at least two DCDC modules; each DCDC module is provided with an H-bridge inversion module H1, a multi-path secondary side transformer T1 and at least two diode rectification units, the primary side of the multi-path secondary side transformer T1 is connected with the H-bridge inversion module H1, the secondary side of the multi-path secondary side transformer T1 is provided with at least two single-phase windings, and the output of each single-phase winding is connected with the corresponding diode rectification unit. The outputs of the diode rectification units are sequentially connected in series; all the H-bridge inversion modules H1 take electricity from the ...

Laminated slab hoisting support capable of effectively preventing slippage

The laminated slab hoisting support capable of effectively preventing slippage comprises a first laminated slab hoisting beam, a second laminated slab hoisting beam and a laminated slab body, an electric telescopic rod is fixedly installed on the inner side face of the first laminated slab hoisting beam, and a storage battery is arranged on the outer side of the electric telescopic rod; the storage battery is fixed to the first laminated slab hoisting beam, a steel bar truss, an upper chord steel bar and a web bar are arranged in the laminated slab body, the inner side of the side plate is rotationally connected with a connecting plate, the top end of the connecting plate is connected with a middle plate, and a second rope is fixed to the upper surface of the middle plate. According to the laminated slab hoisting support capable of effectively preventing slipping, the position of the limiting structure can be conveniently adjusted according to a hoisting point, the limiting structure is ...

Intelligent adjustment type heat dissipation method and system for high-voltage frequency converter

The invention discloses an intelligent adjustment type heat dissipation method and system for a high-voltage frequency converter. The intelligent adjustment type heat dissipation method for the high-voltage frequency converter comprises the steps that (1) a temperature signal of an IGBT is detected in real time, and the temperature signal of the IGBT is converted into a digital signal to be output after shaping and filtering are conducted on the temperature signal; (2) the temperature signal of the IGBT is received and is judged, and when the temperature value is smaller than a preset smallest temperature value, a radiator is controlled to operate at a preset lowest operation frequency; when the temperature value is larger than a preset largest temperature value, the radiator is controlled to operate at a preset highest operation frequency; when the temperature value is between the preset largest temperature value and the preset smallest temperature value, the target operation frequency ...

Superconducting link system

The invention discloses a superconducting link system, comprising a network adapter device, a network protector, an ultralow temperature vacuum multi-channel combined type Dewar, a high temperature superconduction wave filter, an ultralow temperature low-noise amplifier (LNA), a refrigerating system, a high-stability power supply system and an superconducting link intelligent monitoring system, wherein the high temperature superconduction wave filter and the ultralow temperature LNA are arranged in the ultralow temperature vacuum multi-channel combined type Dewar and operate in high vacuum environment with ultralow temperature and long-term holding pressure. In the superconducting link system, a brand new scientific overall structure design and a special manufacturing technology are adopted, thus the superconducting link system has extremely high out-band interference resisting capability and intermodulation interference reducing capacity, and can effectively reduce background noise of ...

Preparation method and application of modified cellulose nanocrystal for calcium ion adsorption

The invention belongs to the technical field of water treatment, and particularly discloses a preparation method and application of a modified cellulose nanocrystal for calcium ion adsorption, and the preparation method of the modified cellulose nanocrystal comprises the steps of (1) reaction, (2) filtration, (3) dialysis and (4) drying. Carboxylate is introduced to the surface of cellulose nanocrystal with the specific surface area far larger than that of cellulose microcrystal to prepare a modified nanoscale cellulose material, the surface of the modified nanoscale cellulose material is provided with negative electricity entities, the negative electricity entities can interact with positive electricity ions, calcium ions in water are efficiently adsorbed, and the purpose of softening hard water is achieved. The preparation method is simple and easy to implement, the raw materials are cheap and easy to obtain, the adsorption effect is good, and the maximum removal rate of calcium ions ...

Intelligent monitoring system for superconducting link

The invention discloses an intelligent monitoring system for a superconducting link. The system mainly comprises a main control module, a power detection module, a power attenuation module, a bypass switching module and a liquid crystal display module. The system has the main functions of performing data acquisition, visual man-machine interface display, alarming and processing, historical information recording and system maintenance on the temperature, a radio frequency circuit and a power supply system of a superconducting link system in real time. The system can ensure the normal operationof the superconducting link system, prevent a too intense signal input into a master station from causing the abnormal operation even damage of the master station, and ensure the normal operation of a network link between an antenna and the master station.

Dragging cable electric leakage fault monitor

The invention relates to an electric leakage fault monitor for a dragged cable. The electric leakage fault monitor comprises a current detection circuit, a controller, a zero sequence current transformer and a resistor R5, the zero sequence current transformer detects the phasor sum of the three-phase current of the dragging cable, and the secondary side inductor L outputs the zero sequence current; the current detection circuit comprises a current variable voltage circuit, an electric control pulse voltage source and a signal amplification circuit, the current variable voltage circuit converts zero sequence current into voltage signals and outputs the voltage signals to the signal amplification circuit, the voltage signals, the secondary side inductor L and the electric control pulse voltage source form a charging and discharging circuit, one end of a resistor R5 is connected with the output end of the current variable voltage circuit, and the other end of the resistor R5 is grounded.

Measuring method for OH free radical in low-temperature plasma degradation organic waste gas

The present invention provides a measurement method of OH free radical in organic waste gas degraded by a low-temperature plasma, comprising the following steps: generating fluorescent product 2,5-dihydroxy-benzoic acid by reacting salicylic acid with hydroxyl radical; loading the salicylic acid on a filter paper; fully expanding the salicylic acid on a dielectric barrier discharge plasma reactor to fully contacting with the gas flowing through the discharge area of the reactor working cavity; taking out the filter paper in 2-4 hours after reaction to detect the formation amount of the 2,5-dihydroxy-benzoic acid, therefore the content of the OH free radical in the low-temperature plasma reaction is calculated. The measurement method has features of simple method, accurate measurement result.

Rotating disc type sponge flat cutting device

The utility model relates to the technical field of sponge processing, in particular to a rotating disc type sponge flat cutting device which comprises a rotating disc and a flat cutting mechanism, a plurality of bearing stations used for bearing sponges are distributed on the top of the rotating disc in a circumferential array mode with the circle center of the rotating disc as the center, and the flat cutting mechanism is located over the other side of the rotating disc. And the bearing station is used for bearing the sponge and driving the sponge to translate. The bearing station is arranged on the rotating disc, the sponge is guided to the rotating disc from the external feeding mechanism through the bearing station and supported, and therefore the effect of automatically feeding and discharging the sponge is achieved, the position accuracy of the sponge feeding mechanism is guaranteed, and the working efficiency is improved. And it is guaranteed that the flat cutting mechanism can ...

Preparation method and application of supported bi-component metal oxide catalytic ozonation catalyst

The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method and application of a supported bi-component metal oxide catalytic ozonation catalyst. The preparation method of the supported bi-component metal oxide catalytic ozonation catalyst specifically comprises the following steps: activating the catalyst carrier, dipping and drying, and calcining to obtain the supported bi-component metal oxide catalytic ozonation catalyst. According to the method, the copper-cobalt-loaded bi-component metal oxide catalyst is adopted to catalyze ozone oxidation to synergistically degrade antibiotics and ammonia nitrogen, under the same condition, the degradation efficiency of the antibiotics is remarkably improved compared with that of single use of ozone or use of unloaded gamma-Al2O3 pellets, and the degradation efficiency of the antibiotics is also greatly improved compared with that of use of a manganese or cerium-loaded single-component catalyst ...