1600 results about "Thyristor" patented technology

The invention provides a valve actuator dispatching control method and system based on AI intelligence, and relates to the technical field of industrial automation control, and the method comprises the steps: collecting the running state parameters of a steam turbine in real time, determining the relation between the steam inlet amount and the valve opening degree under the current working condition to obtain a preliminary valve opening degree estimated value, and carrying out dynamic response compensation; the method comprises the following steps: carrying out comprehensive coupling analysis on a theoretical valve opening value and mechanical parameters such as response time, inertial parameters and an opening limit threshold value of a valve actuator, calculating a dynamic adjustment weight and carrying out boundary constraint processing to obtain a processed parameter, and calling a preset valve opening-silicon controlled trigger angle nonlinear mapping model in a single chip microcomputer based on the parameter; and calculating a final silicon controlled trigger angle by inquiring adjacent data points and a linear interpolation method. By fusing intelligent prediction, multi-dimensional adjustment and a closed-loop feedback mechanism, the valve control precision and response speed are improved, and efficient and intelligent operation of industrial automatic control is achieved.

The invention relates to the technical field of single-phase asynchronous motors, and discloses an electronic soft start control method for a single-phase asynchronous motor, which accurately controls the start process of the motor by combining an MCU (Microprogrammed Control Unit) with an electricity metering chip and a silicon controlled rectifier technology. After the system is powered on, the MCU control unit firstly carries out initialization and reads initial circuit parameters collected by the electricity metering chip, and whether starting conditions are met or not is judged based on the parameters. Once the starting condition is confirmed to be met, the MCU sequentially triggers the auxiliary silicon controlled rectifiers to switch on the starting winding and then triggers the main silicon controlled rectifiers to switch on the main winding, so that the motor enters a running state. As the motor reaches a stable operation state, the MCU control unit closes the auxiliary silicon controlled rectifier to reduce unnecessary energy consumption, and adaptively adjusts the conduction time of the starting winding according to the actual load condition, thereby ensuring that the whole starting process is stable and efficient.

The invention relates to the technical field of single-phase asynchronous motors, and discloses a single-phase asynchronous motor starting control circuit based on an MCU and double silicon controlled rectifiers, which comprises an MCU control unit, a main silicon controlled rectifier, an auxiliary silicon controlled rectifier, an electricity metering chip and a protection circuit. Particularly, in a starting stage, the MCU control unit firstly sends a trigger signal to the auxiliary silicon controlled rectifier to enable the auxiliary silicon controlled rectifier to be in a conducting state, and the auxiliary silicon controlled rectifier is controllably connected with the starting winding to provide extra starting torque for the single-phase asynchronous motor; and after a starting condition is met, the MCU control unit sends a trigger signal to the main silicon controlled rectifier to enable the main silicon controlled rectifier to be in a conducting state, and the main silicon controlled rectifier is connected with the live wire to enable the single-phase asynchronous motor to enter a normal operation state. Thus, the starting winding is only electrified when necessary, energy loss caused by continuous heating of the PTC is avoided, and the overall energy efficiency of the system is improved.

The invention discloses a high-voltage direct current transmission converter thyristor fault identification method based on reliability evaluation. The method comprises the following steps: constructing a stress-degradation-life mapping relation model through a stepped temperature-voltage cooperative stress test; establishing a three-stage Wiener degradation model, and predicting a critical failure point in combination with a dynamic threshold jump mechanism; an FPGA + CPU heterogeneous computing platform is adopted to execute an EM-MCMC joint estimation algorithm in parallel, and parameter updating is accelerated through assembly line MCMC sampling; designing a dynamic correction factor optimization reliability index based on the buffer layer parameters; constructing a dual-channel LSTM network to extract degradation features and generate a dynamic failure threshold value; a converter topology is reconstructed through a graph neural network, and fault positioning and damage grading are realized in combination with a three-level early warning mechanism. According to the method, fault identification is carried out through combination of multi-stress coupling modeling and a dynamic threshold value, the real-time performance is improved through a heterogeneous computing architecture, the false alarm rate is reduced through combination of a dynamic correction and topology reconstruction technology, and accurate identification and operation and maintenance decision support of the thyristor fault are realized.

The invention discloses an optimized reactive power control and fault ride-through method and system for a hybrid commutation converter, and the method comprises the steps: introducing reactive power control and considering the constant voltage control of negative turn-off angle limitation, achieving the control of an extremely low turn-off angle through the active turn-off of a full-control device in the converter under a steady-state working condition, and further meeting the demands of a high power factor; the investment of passive filter equipment is reduced; under the alternating current fault working condition, forced commutation and negative turn-off angle operation are achieved through active turn-off of a full-control device, the receiving end power grid voltage is effectively supported while commutation failure of a half-control thyristor in the hybrid commutation converter is avoided, and the active power transmission level during the fault period is improved. The full-control characteristic of the reverse blocking type integrated gate commutation thyristor in the hybrid commutation converter is fully utilized, reactive power control under the steady-state working condition and stable power transmission under the alternating-current fault are achieved by optimizing active turn-off control, and the method has wide applicability and good application prospects.

The invention relates to the technical field of power systems, and discloses a voltage regulation system of reactive power compensation equipment, which is characterized in that harmonic interference is filtered and eliminated through a voltage reactive power sensing unit, and accurate power grid parameters are acquired; a load trend pre-judgment unit analyzes the historical load curve and the real-time change trend to generate a future pre-judgment signal; the dynamic compensation calculation unit combines the current power grid state with the prediction to calculate the optimal compensation capacity and generate a switching instruction, after the hybrid switching actuator receives the instruction, a thyristor is triggered firstly to realize inrush current-free conduction, a contactor is switched to maintain low power consumption after the current is stable, and meanwhile, the compensation state monitoring unit performs closed-loop adjustment on parameter deviation, so that the optimal compensation capacity is obtained. The multi-dimensional protection unit prevents overvoltage, overcurrent and overheating, the double-path power supply guarantees continuous operation when the main power supply is abnormal, the intelligent communication unit realizes data uploading and remote cooperation, quick response switching of reactive compensation equipment and guarantee of safety of a large-scale power grid are realized, and inrush current impact in the switching process is effectively inhibited.

The invention discloses a bidirectional hybrid output direct-current transformer and a fault current limiting design method thereof, and the medium-voltage side and the high-voltage side of the bidirectional hybrid output direct-current transformer are respectively composed of three thyristor valve groups and three sub-module bridge arms, and are connected through a medium-frequency transformer. The thyristor valve group is formed by reversely connecting two groups of series thyristors in parallel, and the medium-voltage side sub-module bridge arm and the high-voltage side sub-module bridge arm are respectively composed of NM half-bridge sub-modules and NH half-bridge sub-modules. According to the invention, the sub-module bridge arms with strong control capability are combined with the thyristors and the diode valve groups which are low in cost, low in loss and high in power density, bidirectional power transmission and reliable turn-off of the thyristors can be realized through coordination and cooperation of the middle-voltage side bridge arms and the high-voltage side bridge arms, smooth direct current is ensured, and a filter does not need to be installed. When a short-circuit fault occurs in the outgoing submarine cable, a fault current active suppression strategy is provided, and the scheme can effectively reduce the peak value of the fault current and eliminate the current-limiting inductance.

FinFET multi-diode thyristor switches for protecting high data rate communication system interfaces are provided. In certain embodiments herein, high voltage tolerant FinFET thyristors are provided for handling high stress current and high RF power handling capability while providing low capacitance to allow wide bandwidth operation. Thus, the FinFET thyristors can be used to provide electrical overstress protection for ICs fabricated using FinFET technologies, while addressing tight radio frequency design window and robustness. In certain implementations, the FinFET thyristors include a first thyristor, a FinFET triggering circuitry and a second thyristor that serves to provide bidirectional blocking voltage and overstress protection. The FinFET triggering circuitry also enhances turn-on speed of the thyristor and / or reduces total on-state resistance.

The invention provides a metallurgical chemical solid waste pretreatment vertical electric heating roasting furnace device and a using method thereof.The furnace body is of a hollow cylindrical vertical structure, a barrel is divided into a solid reduction area, an oxidation reduction area and a furnace charge preheating area, the barrel of the solid reduction area and the barrel of the oxidation reduction area are surrounded by flat rectangular red copper pipes, and an auxiliary induction bar is arranged in the center of the barrel; and the feeding and discharging device is connected to the PLC automatic control module. The power supply control and heat supply device is connected with the red copper pipe through a silicon controlled rectifier medium-frequency power supply, and an air supply and exhaust device, a temperature control device and a sealing device are additionally arranged. Fossil fuel is replaced by electric heating, carbon emission is reduced, environmental protection is achieved, temperature control is accurate, heat efficiency is high, and energy consumption and cost can be saved. One set of equipment is suitable for different solid waste raw materials, pretreated products are obtained through different roasting methods, the equipment is simple, investment is saved, the technological process is short, applicability is high, heating is even through the structural design, sealing is good, continuous production can be achieved, and heat efficiency and production efficiency are improved.

The invention relates to the technical field of optocouplers, in particular to a planar SSR optocoupler. Through a light emitting diode arranged on an input loop and a bidirectional photosensitive silicon controlled rectifier and a bidirectional thyristor arranged on an output loop, the bidirectional photosensitive silicon controlled rectifier can be driven by light emitted by the light emitting diode to open a gate pole of the bidirectional thyristor, and the thyristors T1 and T2 are driven to control a load LOAD, so that the product can complete the function of a relay; the number of electronic components in the circuit is smaller, the probability that the whole circuit breaks down is greatly reduced, various electronic components can be protected by means of the shading body, the influence of external environment factors on the various electronic components is reduced, and therefore the probability that the electronic components in the circuit break down can be further reduced, and the service life of the circuit is prolonged. The fault probability of the whole circuit is reduced; the problem that the circuit damage probability is increased due to the fact that an existing relay circuit needs to be composed of a plurality of electronic components is solved.

The invention belongs to the technical field of extra-high voltage direct current transmission, and discloses an IGCT single-valve structure for a converter valve. The IGCT single-valve structure comprises a shielding cover assembly, an IGCT valve string unit, a frame assembly, a water pipe assembly, a resistance-capacitance absorption assembly and a water-cooled reactor. Wherein the IGCT valve string unit, the water pipe assembly and the resistance-capacitance absorption assembly are arranged on the frame assembly, and the shielding cover assembly covers the periphery of the outer portion of the frame assembly; the water-cooling reactor is arranged in the shielding case assembly and connected with the frame assembly and the shielding case assembly, and the water pipe assembly is connected with a water path of the water-cooling radiator in the IGCT valve string unit and a water path of the water-cooling reactor. The problem of hidden danger of commutation failure in the traditional direct-current power transmission converter valve technology can be solved, the function of the circuit breaker is added, fault current can be blocked, the new single valve structure can replace the single valve layer of the traditional direct-current power transmission converter valve of the thyristor, and the engineering replacement cost and the operation difficulty are greatly reduced.

The invention provides a current source type hybrid direct-current power transmission system based on an injection type power grid commutation converter, and relates to the field of high-voltage direct-current power transmission, and the system comprises a rectification station which at least comprises a thyristor-based power grid commutation converter and is used for converting alternating current into direct current; the inverter station at least comprises an injection type power grid commutation converter and is used for converting the direct current output by the rectifier station into alternating current; and the control module is used for controlling the operation of the rectifier station and the inverter station based on the trigger time sequence constraint, and has the advantages of completely inhibiting the commutation failure and reducing the loss.

Disclosed in the present invention is a ground fault device end-of-life self-test system. An induction coil and a neutral coil are used for sensing and acquiring a ground fault leakage current signal of a live wire or a neutral wire. A trip device is used for cutting off the power supply to a load in the event of a ground fault by driving a solenoid by means of a thyristor which is triggered by an IC1 to turn on. A manual test button is used for manually testing the function of a ground fault device. A rectifying circuit is used for rectifying an alternating current (AC) and outputting same to a direct current, and providing the direct current to IC1 and IC2 direct current power supplies. A ground fault detection circuit is used for completing ground fault detection, and controlling the drive to trigger the thyristor to turn on or off. A ground fault self-test control circuit is used for controlling the testing of a ground fault detection function without affecting normal ground fault detection and protection functions.

A semiconductor device has a first substrate and a first semiconductor layer formed over the first substrate. A second substrate is disposed over a surface of the first semiconductor layer opposite the first substrate. The first semiconductor layer and second semiconductor layer can be silicon carbide or cubic silicon carbide. The first substrate and a portion of the first semiconductor layer are removed to reduce defects in the first semiconductor layer. A second semiconductor layer is formed over a remaining portion of the first semiconductor layer. A third semiconductor layer is disposed over the second semiconductor layer. The third semiconductor layer can be silicon. The third semiconductor layer can be disposed over the second semiconductor layer by direct wafer bonding. An electrical component is formed within the third semiconductor layer. The electrical component can be a power MOSFET, IGBT, CTIGBT, diode, and thyristor.

The invention relates to the technical field of electrical engineering, and discloses a converter valve short-circuit current test system and method, and a generator branch in the system comprises a short-circuit generator, a short-circuit control unit and a bidirectional thyristor valve; one end of the generator branch is connected to one end of the sample valve through the short circuit control unit and the bidirectional thyristor valve in sequence; the other end of the sample valve is connected to the other end of the generator branch; the capacitor branch is arranged at two ends of the sample valve in parallel; the capacitor branch comprises a short-circuit valve body control unit, a capacitor bank and a direct-current power supply; one end of the short-circuit valve body control unit is connected to one end of the sample valve, and the other end is connected to the other end of the sample valve through the capacitor bank; the direct-current power supply is arranged on the capacitor bank in parallel; according to the invention, independent decoupling adjustment of the alternating current component and the direct current component of the short-circuit current is realized, and the test requirements on the gradually increased peak value of the short-circuit current, the thermal capacity and the short-circuit current containing the high-proportion direct current component are met.

The present invention discloses a bidirectional gate controlled thyristor structure, comprising a first P-type epitaxial layer, a second P-type epitaxial layer, a first N-type deep well doping type well region and a first N-type well doping type well region which are stacked; a first P-type high voltage doping type well region is provided on the first P-type epitaxial layer, a first P-type well doping type well region is provided inside one side of the first P-type high voltage doping type well region, a first P-type heavily doped active region is provided at the top of the other side of the first P-type high voltage doping type well region, a plurality of groups of second P-type heavily doped active regions and first N-type heavily doped active regions arranged in parallel are provided at the top of the first P-type well doping type well region, and the first P-type heavily doped active region and the plurality of groups of first P-type heavily doped active regions and first N-type heavily doped active regions arranged in parallel are isolated from each other. The ring-shaped gate controlled structure of the present invention adjusts the carrier transport path to a deeper level, solving the problems of low voltage maintenance and low current discharge efficiency of the existing thyristor structure.

The invention provides a simulation method and system with controllable split-phase voltage drop time difference, and relates to the technical field of electric power testing, and the method comprises the steps: adjusting voltage through a three-phase voltage regulator, employing a bidirectional silicon controlled rectifier and IGBT hybrid switch structure to achieve voltage drop, collecting and processing a three-phase voltage signal through a digital signal processor, and extracting zero crossing point information; and a control pulse signal with phase compensation is generated, the conduction time sequence of the switch element is controlled to realize soft switching, and the industrial computer receives and processes the signal and displays a voltage drop waveform. The split-phase voltage drop time difference can be accurately controlled, and the simulation precision and the system reliability are improved.

The invention relates to the technical field of solar cell manufacturing, and discloses a method for electroplating copper and tin grid lines on a solar cell, which comprises the following steps of: S1, copper electroplating: putting a cell piece on an electroplating tool, and putting the cell piece into a copper liquid tank for electroplating copper layers on a P surface and an N surface; wherein a very-low-frequency power supply is adopted. And S2, cleaning the copper liquid on the battery piece. S3, tin electroplating: the battery piece after the copper liquid is cleaned is placed in a tin liquid tank for electroplating tin layers on the P surface and the N surface; wherein a very-low-frequency power supply is adopted. And S4, cleaning the tin liquid on the battery piece. And S5, the cleaned battery piece is taken out, and grid line electroplating is completed. The very-low-frequency power supply is used for replacing a silicon controlled rectifier direct-current power supply, and self-developed voltage and current parameters are matched, so that the compactness and the conductivity of the HDT high-efficiency single-crystal heterojunction solar cell on an electroplated metal grid line film layer are improved, and the conversion efficiency of a cell piece is improved.

The invention discloses a converter valve multistage thyristor level closed-loop test device which comprises a CPU control module, a photoelectric conversion module, an analog quantity acquisition module, a switching value module, an output control unit, an impedance test unit, an overvoltage and overcurrent protection module, a safety protection module, a man-machine interaction unit module and a power supply module. The CPU control module is respectively connected with the photoelectric conversion module, the analog quantity acquisition module, the switching value module, the output control unit, the impedance test unit, the overvoltage and overcurrent protection module, the safety protection module and the man-machine interaction unit module; the power supply module is connected with the CPU control module, the safety protection module, the photoelectric conversion module, the analog quantity acquisition module, the overvoltage and overcurrent protection module, the switching value module, the output control unit, the impedance test unit and the man-machine interaction unit module. According to the invention, the automation degree and the field adaptability of the test are improved, and the field maintenance efficiency and the visual analysis capability of the operation state of the thyristor are improved.

The invention belongs to the technical field of power transformation equipment, and particularly relates to a low-voltage dynamic reactive compensation switching device which comprises a shell, a photoelectric isolation module and a communication module. The shell is in an inverted-T shape, a switching switch is arranged at the front end of the shell, wiring ports are symmetrically formed in the upper side and the lower side of the shell, and wiring bolts are installed on the wiring ports. A photoelectric isolation module is arranged on one side of the shell, and the heat dissipation holes dissipate heat for the photoelectric isolation module. According to the scheme, a thyristor and contactor hybrid switching switch is adopted, zero-crossing switching is realized by the thyristor during dynamic load fluctuation, and inrush current control is less than or equal to 10 times of rated current. And when the static state is stable, the contactor is automatically switched to be conducted, and the power consumption is reduced to 1.5 W and is greatly reduced compared with a pure thyristor scheme, so that the impact is avoided and the energy consumption is reduced. The thyristors are in bidirectional anti-parallel connection, and are matched with zero-cross detection logic of the controller, so that overvoltage and transient harmonic waves in the switching process are thoroughly eliminated, no interference is caused to a power grid, and the service life of the device and power grid equipment is prolonged.

The invention discloses a thyristor type device leakage current monitoring method and circuit and a power electronic device.The method comprises the steps that in response to a system turn-off instruction, a first control signal is sent to a device turn-off module; the device turn-off module is used for conducting a turn-off branch of the thyristor device according to the first control signal; acquiring a leakage current sampling signal from a leakage current monitoring module; the leakage current monitoring module is used for converting the gate current of the thyristor device into a leakage current sampling signal; and generating a leakage current monitoring result based on the leakage current sampling signal. According to the invention, real-time and accurate measurement of the leakage current can be realized on the premise of not influencing system operation.

The invention provides a multi-path vibration energy collection device, and the device comprises a mass block which can generate relative movement under the excitation effect; the piezoelectric cantilever beams are arranged on the two transverse sides of the mass block and used for responding to high-frequency micro-amplitude vibration energy; the permanent magnet assembly is fixed in the moving direction of the mass block and is matched with the induction coil to realize magnetoelectric energy conversion; the piezoelectric cantilever beam is connected with the bridge rectifier and the thyristor threshold trigger circuit 1, and the permanent magnet assembly is connected with the bridge rectifier and the thyristor threshold trigger circuit 2 to form a double-independent energy collection channel. The method has the following advantages: (1) a path orthogonal decoupling design is adopted, so that a structure and energy dual-independent acquisition path is realized; (2) the energy conversion efficiency is improved based on a coupling response mechanism of mass block inertia driving; and (3) a thyristor threshold triggering mechanism realizes micro-energy efficient conversion, and the output is stable and reliable.

The invention discloses a high-voltage bidirectional silicon controlled rectifier electrostatic protection device and a manufacturing method. The high-voltage bidirectional silicon controlled rectifier electrostatic protection device comprises a P-type substrate, a P-type well and a high-voltage N well, the emitter P + injection of a parasitic PNP triode and the emitter N + injection of a parasitic NPN triode in the P-type well are arranged alternately, so that the length of a transverse discharge path of the silicon controlled rectifier is reduced to the greatest extent, the square resistance of a PNPN positive feedback conduction path is greatly reduced, and the key problem that a symmetrical bidirectional silicon controlled rectifier structure cannot be effectively opened in a high-voltage window of more than 70V is solved; in addition, the layout can provide an additional parasitic NPN triode path for a silicon controlled rectifier path, the effective area of an emitter of the parasitic NPN triode and the proportion of the emitter in a silicon controlled rectifier loop are increased, and the current discharge capacity of the device is further improved. Therefore, reference can be provided for the structural design of the high-voltage symmetrical bidirectional silicon controlled rectifier electrostatic protection device, and the silicon controlled rectifier can be effectively applied to ESD protection of a high-voltage bidirectional port.

The invention discloses a low-voltage line intelligent voltage regulation voltage stabilizer control system, and relates to the technical field of voltage stabilizer control, an intelligent control unit judges whether the current line voltage needs voltage regulation control based on a control algorithm, if yes, a corresponding voltage regulation control instruction is generated, a silicon controlled rectifier switching module executes non-contact on and off operation, and the voltage regulation control is completed. The voltage regulation compensation module is used for carrying out voltage compensation on the basis of the output of the voltage transformation module, so that the output voltage is controlled within a preset range, and when the power grid voltage is detected to be recovered and stable within a set time, and when the power grid voltage is detected to be abnormal, the voltage regulation compensation module is used for carrying out voltage compensation on the basis of the output of the voltage transformation module. And the intelligent control unit is automatically switched into a bypass for operation. According to the control system, a voltage stabilization control framework with high response speed, three-phase independent adjustment capability, an intelligent dormancy mechanism and a complete fault protection system is constructed, and the intelligent level and the operation performance of the low-voltage power distribution system are remarkably improved.

The invention discloses a high-maintaining voltage bidirectional thyristor structure, comprising a first P-type epitaxial layer and a second P-type epitaxial layer, characterized in that it also comprises a first N-type well doping type well region, wherein the first P-type epitaxial layer is provided with a first P-type high-voltage doping type well region, a first P-type semiconductor, a first N-type heavily doped active region and a first P-type heavily doped active region arranged side by side in sequence from the inside to the outside, the first P-type high-voltage doping type well region wraps the first P-type semiconductor, and the first P-type semiconductor wraps the first N-type heavily doped active region and the first P-type heavily doped active region; and the second P-type epitaxial layer is provided with a second P-type high-voltage doping type well region, a second P-type semiconductor, a second N-type heavily doped active region and a second P-type heavily doped active region arranged side by side in sequence from the inside to the outside. The invention reduces the effective emission area of ​​the intrinsic SCR, improves the maintaining voltage, and solves the problem that the existing SCR structure is prone to cause latch-up effect.

The invention provides a health state depth feature extraction method for key components of an extra-high voltage direct current transmission converter valve, and belongs to the technical field of extra-high voltage transmission equipment.The health state depth feature extraction method comprises the steps that firstly, different fault state models are constructed through PSCAD simulation, data are collected, and dimension reduction processing is conducted on multi-source heterogeneous data through principal component analysis; and establishing a time sequence sliding window mechanism to calculate data characteristic parameters. And then temperature features are extracted based on a thyristor junction thermal diffusion mechanism equation, deep feature extraction is performed by using a multi-head self-attention enhanced bidirectional long-short-term memory network, multi-source data such as infrared temperature measurement and ultraviolet discharge are fused, and abnormal feature representation is calculated through an isolated point feature evaluation function. And finally, constructing a feature vector space containing electrical features, temperature features, isolated point features and multi-component correlation features, outputting complete health state feature representation, and providing a basis for state evaluation and fault prediction of the converter valve.

The invention discloses a fault detection method and system for an SVF multi-stage full-bridge sub-module in an SLCC, and the method comprises the steps: constructing a converter valve test model which comprises a converter valve, a valve control unit and a low-pressure pressurization unit; wherein the converter valve comprises a full-bridge sub-module; based on a valve tower structure, wiring complexity and test voltage safety, performing number optimization on series connection and parallel connection of full-bridge sub-modules, and setting test power supply voltage; and based on the topological structure of the full-bridge sub-modules, performing low-voltage pressurization test on the full-bridge sub-modules by using a low-voltage pressurization unit to obtain the working states of the full-bridge sub-modules, judging faults of the full-bridge sub-modules connected in series, and positioning fault positions. According to the method, the detection efficiency of the multi-stage full-bridge sub-module is improved, all the full-bridge sub-modules of the valve tower can be rapidly and accurately detected and diagnosed only through one-time wiring, the field handover test time is shortened, and SLCC direct-current power transmission project construction is supported.

The invention discloses a multi-port direct current change-over switch based on a controllable negative voltage source, and belongs to the technical field of power equipment. Comprising X (X = 5 or 3) main branches, a commutation branch and X groups of controllable conduction switches, each main branch is composed of a through-flow vacuum switch, and the commutation branch is composed of a controllable negative voltage source and a square wave resonance direct current circuit breaker which are connected in series. The five main branches of the sending end are connected with a sending end positive pole rectifier and the like, and the three main branches of the receiving end are connected with a receiving end positive pole rectifier and the like and are all connected with the commutation branch through a controllable conduction switch. The controllable negative voltage source is formed by connecting a double-thyristor branch circuit and a negative voltage source in parallel, and the square wave resonance direct current circuit breaker comprises a temporary through-flow branch circuit and the like. The vacuum switch is used for replacing an SF6 switch, so that the switch is good in environmental protection property; the converter branch and the lightning arrester are shared, so that the use of high-price equipment is reduced, and the cost is reduced; a controllable square wave voltage source is utilized to excite high-frequency oscillation of an LC branch, and the element size is reduced; and rapid transfer of current in different directions can be realized, and the system response speed is improved.

The invention relates to the technical field of welding, and provides a low-load voltage circuit and a lithium battery welding machine. The circuit comprises a main control module, a voltage detection unit, a switching circuit, a pulse modulation unit and a current sampling feedback unit. The voltage detection unit monitors the end voltage of a welding gun of a welding machine in real time, the switching circuit limits the output voltage to be smaller than a safety threshold value of 36 V in a no-load mode, and a built-in bidirectional thyristor achieves isolation of a high-voltage loop and a low-voltage loop. The pulse modulation unit adjusts the on-off frequency of a main power loop, and the current sampling feedback unit dynamically adjusts the pulse duty ratio so as to accurately control the welding current. The lithium battery welding machine integrates the circuit and is provided with a welding gun assembly, a main transformer and a power supply module, the electric shock risk is effectively reduced, and the welding quality and efficiency are improved.

The invention discloses a power supply system and method for substation equipment, and relates to the technical field of substation power supply, and the system comprises a data collection module which is used for synchronously collecting three-phase voltage and current signals of a substation load; the harmonic characteristic analysis module is used for carrying out harmonic analysis on the collected signals and calculating the amplitude and phase dispersion of each harmonic; the dynamic weight calculation module is used for calculating a dynamic harmonic weight factor according to the harmonic analysis result; the equivalent reactive power decision module is used for calculating equivalent reactive power and generating an optimal capacitor switching instruction in combination with harmonic weight and temperature compensation; the temperature compensation module is used for monitoring the temperature of the capacitor in real time and calibrating the actual capacity of the capacitor; and the flexible switching execution module is used for triggering a thyristor near the voltage zero crossing point. By constructing the harmonic phase dispersion analysis mechanism and the harmonic weight factor dynamic correction model, the transient characteristic and steady-state distortion difference of the load harmonic can be analyzed more accurately.