286results about How to "Reduce no-load loss" patented technology

This invention relates to a load capacitance and voltage regulation switch characterizing in the following structure: a voltage-regulation static contactor is mounted on an insulated drum of a load capacitance-regulation part, a voltage -regulating bracket is set in the drum, a voltage-regulation dynamic contactor and a transition resistor are set on the bracket to integrate the load capacitance and voltage regulation, a set of operation unit is used between the quick unit of the capacitance and the voltage regulation parts by an electromagnetic clutch and an electric control box is set for adjusting capacitance and voltage automatically according to the change of loading current and voltage of a transformer.

The invention discloses a welding process for a carbon steel process pipeline. In the welding process, manual argon arc welding is adopted to process a backing weld; flux-cored wire CO2 gas shielded welding is adopted on a filling cover surface; CO2 adsorbs heat in the process of protecting a weld pool, can reduce the temperature on the periphery of the weld pool and take the effect of constricting electric arc, so that the heat input is low and the weld quality is high; the manual arc welding is replaced; no rod stub is generated; few welding slags are generated; little smoke dust is generated; the welding production efficiency is high; and an attractive weld joint is formed.

The present invention discloses a magnetic suspension flywheel battery for a sandwich-type electric car and a work method thereof. A vertical rotation shaft is arranged at the center of the internal portion of a vacuum chamber, a disc-type flywheel motor is coaxially arranged at the center of the axial direction of the vertical rotation shaft, disc-type magnetic bearings having the same structure, being arranged at the axial direction in the longitudinal symmetry mode relative to the disc-type flywheel motor and being sleeved at the outer portion of the vertical rotation shaft are coaxially arranged at the upper portion and the lower portion of the disc-type flywheel motor, and each disc-type magnetic bearing is wound with a set of radial control coils; the disc-type flywheel motor is composed of a stator, two rotors and two sets of permanent magnets, the stator is located at the center of the disc-type flywheel motor and coaxially arranged at the outer portion of the vertical rotation shaft, and the two rotors are respectively and symmetrically arranged at upper and lower sides of the stator and coaxially and fixedly sleeved on the vertical rotation shaft; and the two sets of the permanent magnets are respectively pasted on the surfaces, back to the stator, of the two rotors along the peripheral directions, the whole structure of the flywheel battery is a disc-type structure, the disc-type magnetic bearings and the disc-type flywheel motor are both the flat structures to inhibit the gyroscopic effect of the rotors.

The invention relates to a coating method of a winding amorphous iron core insulating coating. The coating method comprises a first step that a whole amorphous iron core is arranged in epoxy glue to conduct vacuum impregnation, a second step that the surface of the amorphous iron core is coated with epoxy resin, and a third step of heating and solidifying after the amorphous iron core is coated with the modified epoxy glue coating. Gaps between amorphous strips are sealed and have certain strength after the epoxy glue impregnation, the coating is neat in surface and uniform in thickness, vibration and noises of the iron core are reduced, and integrated installation is convenient. The coating is thinner than general coating technique and solidifying time is shortened. The epoxy glue enables solidifying contraction percentage to be low, the epoxy glue coating has good adhesiveness and elasticity and has little stress to the iron core, and the coating has little influence on initial magnet conductivity and inductance of the amorphous iron core. The amorphous iron core dealt with the coating method can greatly reduce no-load loss.

The invention discloses a destressing method and device for an amorphous alloy transformer iron core, wherein the method comprises the steps of: loading an iron core to a heating furnace chamber; exhausting the air inside the furnace chamber by injecting an inert gas into the heating furnace chamber; heating up the heating furnace chamber; keeping the temperature of the heating furnace chamber when the iron core temperature reaches a keeping temperature, wherein the iron core keeping temperature is 342-348 DEG C, and the temperature keeping time is 40-50 min; cooling the iron core, wherein the cooling step comprises a step of cooling the heating furnace chamber and a step of cooling the iron core along with the furnace; and keeping to feed the inert gas into the furnace in the processes of heating up, keeping temperature and cooling the heating furnace chamber. By adopting the method and the device disclosed by the invention, the stresses of the amorphous alloy generated in the processes of fast quenching, winding, cutting, forming and the like are effectively eliminated, and no-load loss of the amorphous alloy iron core is obviously reduced.

The iron core is pieced together from iron cores with simple frame in same or near shape. Each simple frame is prepared by winding one or several pieces of silicon steel strip. Characters are that layered stagger cutting yoke part of wound closed single frame forms kerf composed of multiple short slots distributed in stagger positions. Opening up cut slots layer-by-layer forms a U shaped frame with an opening. Stagger lapping opening parts of U shaped frames forms an iron core with simple frame in closed magnetic circuit. Advantages are: fine capability, low noise, saving material, low cost. Comparing with transformer in lamination type, the disclosed transformer is structured with opened iron core so that coil can be wound alone and replaced easily. Moreover, iron core is prepared by winding and cutting so that it is easy to manufacture iron core.

The invention relates to an energy router device applied to an intelligent distributed energy network. The energy router device comprises an A unit being a three-phase pulse width modulation (PWM) bidirectional rectification unit, a B unit being an isolation-type bidirectional soft switch Cuk conversion unit, a C unit being a dual-active DC / DC conversion unit, a D unit being a three-phase four-wire soft switch inversion unit, an E unit being a soft switch single-phase full-bridge bidirectional inversion unit and an F unit being a photovoltaic Boost conversion unit and also comprises a first DChigh-voltage bus and a second DC low-voltage bus, wherein the dual-active DC / DC conversion unit comprises a closely-coupling high-frequency transformer, soft switching of each unit can be achieved byan auxiliary circuit or a control strategy, the energy loss and the loss of a switch tube device are greatly reduced. The distributed energy network is divided into three layers of power grid tree-shaped architectures by the intelligent distributed network technology, and the router is applied to a power distribution network and a micro power grid to complete different functions.

The invention discloses a flyback convertor controlled by a self-oscillation start output end, which comprises a flyback power conversion main circuit, a start oscillation circuit, a cut-off device and a PWM control circuit. The start oscillation circuit is connected with an MOS main switch tube grid in the flyback power conversion main circuit, and the cut-off device is connected in a return circuit of the start oscillation circuit. The PWM control circuit outputs two paths of signals, one path of trigger signal is connected to the cut-off control end of the cut-off device for controlling the cut-off of the start oscillation circuit, and the other path of PWM drive signal is connected to the MOS main switch tube grid in the flyback power conversion main circuit. The invention has the following characteristics that the flyback convertor does not need an extra auxiliary power supply to supply power to the PWM control circuit, easily realizes the control mode of synchronous rectification, and also easily realizes various protective circuits, and additional functions such as parallel current equalization, and so on; and the band width of a control loop is not limited to make the dynamic performance of the circuit better.

The invention relates to a Bluetooth control-based wireless electric energy transmission apparatus. A rectifying module converts mains supply into a direct current to be sent to a high-frequency inversion module; a Bluetooth module in the high-frequency inversion module receives a signal from a receiving end and performs judgment to output a control signal to a driving module to control operation of the inversion module; the inversion module outputs a high-frequency alternating current to be transmitted outwards through modes of a transmitting inductive coil and capacitive resonance; an electromagnetic receiving module receives energy, and the energy is converted into a direct current through a rectifying and filtering module to be output to an auxiliary power supply module; the auxiliary power supply module converts a voltage into a voltage which is required by a load and a chip; and a sampling module samples the voltage and current at the input end of the auxiliary power supply module, processes the sampled voltage and current and transmits the processed voltage and current through the Bluetooth module at the receiving end. An E type inversion circuit is adopted, so that the advantages of simple circuit, easy control, low cost and the like can be achieved; and in addition, after Bluetooth control is added, no-load loss can be lowered, overvoltage current and near-distance protection can be realized, the transmission efficiency can be improved, and the problems existing in multi-load voltage matching and the like can be solved.

The present invention belonging to a power control device and more particularly relates to the transformer load control caused by multiple charging piles. The technical scheme is that the system comprises a controller host machine (1), a plurality of controller extension machines (2) arranged at charging piles (5) and a communication bus (3) which is connected between the controller host machine (1) and the controller extension machines (2). By applying the system and the method, all charging piles in a housing estate can be controlled in real time, a power use peak is staggered, construction investment can be reduced for new residential housing estates and enterprises, transformer zero load loss can be reduced, and electrical system transformation difficulty and cost can be greatly reduced for a built housing estate with the need of adding charging piles.

The invention, which relates to the technical field of energy systems, provides an energy router device applied to wind-light energy storage and a control method thereof. The device comprises a bidirectional rectifying unit, a resonant bidirectional DC-DC conversion unit, a photovoltaic Boost transform unit, a bidirectional DC-DC conversion unit, a soft switching single-phase full-bridge inverterunit, a three-phase PWM rectifying unit, a high-voltage direct-current bus, a low-voltage direct-current bus, a DSP controller, a voltage sensor and a current sensor. Meanwhile, on the basis of a hybrid energy storage coordinated control strategy of a stochastic robust optimization method, the device has seven kinds of working modes. In addition, the invention also provides a control method of anenergy router device applied to wind-light energy storage. According to the invention, on the basis of the multi-unit topological structure, the electric energy with various voltage levels can be provided and various load and energy storage device's needs are met; and the photovoltaic-fan complementary power generation is realized by the control method and the hardware structure.

The invention discloses a phase shift balancing device of an 18-pulse rectifier. The phase shift balancing device comprises a phase shift auto-transformer and a three-phase balancing electric reactor, wherein the phase shift auto-transformer has a group of inputs with 3fai 380V and two groups of outputs 3fai 380V, and two groups of outputs respectively shift phases at the same angle toward the opposite direction. The impedance of the three-phase balancing electric reactor is matched with the phase shift auto-transformer, and input end of the three-phase balancing electric reactor is connected with the input end of the phase shift auto-transformer and correspond to the phase shift auto-transformer in phase. The input end of the phase shift auto-transformer is connected with a grid side power supply, and the two groups of outputs of the phase shift auto-transformer and an output of the three-phase balancing electric reactor are balanced to form a part of the rectifier to supply electricity. The phase shift balancing device of the 18-pulse rectifier consists of a polygonal auto-transformer and the three-phase balancing electric reactor with small capability, calculated capability is about 17% of calculated capability of a traditional extending-edge connecting phase-shifting transformer, materials are saved, product volume and weight are decreased, and the product cost is reduced.

A mining explosion-proof all-insulation dry type transformer with an amorphous alloy iron core for a mobile transformer substation comprises an integral winding, the iron core, an upper clamp, a lower clamp and a shell, wherein the integral winding includes low-voltage coils and high-voltage coils. The mining explosion-proof all-insulation dry type transformer is characterized in that insulation layers are arranged among layers of the low-voltage coils, the high-voltage coils are arranged on the outer layer of the low-voltage coils, each insulation layer is arranged between each two adjacent layers of the high-voltage coils, an outer insulation layer covers the high-voltage coil, and the integral winding has the square section. The iron core is the amorphous alloy iron core, and an assembling lap joint of the iron core is arranged on the lower portion. The upper clamp and the lower clamp are non-metallic parts cast by epoxy resin and reinforced by filled glass fibers, the U-shaped sections of the upper clamp and the lower clamp cap the upper yoke and the lower yoke to press the upper end face and the lower end face of the winding and are fastened by pull bolts, and the pull bolts are symmetrically mounted on the low-voltage side and the high-voltage side to fasten the upper clamp and the lower clamp. The mining explosion-proof all-insulation dry type transformer has the advantages of long service life, low loss, low noise, no maintenance or pollution, high reliability, flame retardance, fire resistance, recyclability after being used up and the like.

The invention provides a coordinated control method for a low-voltage flexible distribution network power supply system. The system comprises four distribution transformers T1-T4, four sections of 400V low-voltage AC (alternating current) buses and four flexible DC (direct current) converters, wherein the four sections of 400V low-voltage AC buses are connected through bus coupler switches; a DC bus is further connected to an energy storage system and a distributed photovoltaic system. The coordinated control method is used for performing coordinated control for different fault conditions of bus coupler switch fault, incoming line power loss, flexible direct current converter fault, energy storage converter fault and photovoltaic converter fault in different operation modes. According to the system, interconnection of multiple lines of the distribution network is realized by the flexible DC converters, power wheeling support between the lines is realized, and after a certain distribution line fails and breaks, the flexible DC converters perform islanded operation with load; meanwhile, interconnection is realized on the DC link with photovoltaic and energy storage systems, and an optical storage and flexible DC combined hybrid system is formed.

The invention discloses an aluminum foil coil for a non-crystalline alloy oil immersed type distribution transformer, a transformer body structure and a method for manufacturing the transformer. The transformer comprises a four-frame five-column type or three-frame three-column type non-crystalline alloy iron core, high and low voltage coils sleeved on iron core columns, upper clamping pieces and lower clamping pieces arranged on upper and lower ends of the high and low voltage coils and end clamping pieces arranged on the outer ends of high voltage coils on the side columns, and the transformer also comprises an insulated framework sleeved on the iron core columns and a plurality of aluminum-copper transition connectors fixed on the upper clamping pieces through conducting wire clamps. The aluminum foil is used as a material of the low voltage coils and directly wound on the insulated framework, and the head ends and the tail ends of the low voltage coils are welded with aluminum bars of the transition connectors respectively, and the outer surfaces of the low voltage coils are covered by main insulation; and the high voltage coils are wound on the outer surface of the main insulation. In the technical proposal of the invention, aluminum replaces copper, so that the transformer has the characteristics of low no-load loss of common non-crystalline alloy distribution transformer, and the transformer also has the advantages that the transformer has low material cost and light weight, and minimizes the influence of copper price raising on cost of the non-crystalline alloy distribution transformer, and lowers consumption of insufficient copper resources and the like.

The invention relates to a C class non-envelop winding dry type transformer that comprises iron core, high voltage winding and low voltage winding. Its feature is that, the iron core is made up of silicon steel of grain orientation high magnetic diffusivity lab joint together five steps and 45 degree full juncture; the low voltage winding with high capacity is winded from copper foil and there is insulating material that can endure 220 degree centigrade is set between the layers; mica strip that can endure 500 degree centigrade constructs cooling air duct, and the whole winding would form a rigid body after dipping into vacuum pressure lacquer and high temperature solidifying; the high voltage winding is continuous structure and is construct by C class glass fiber covered wire, and there is mica strip that can endure 500 degree centigrade is set between the layers, the whole winding would form a rigid body after several times of dipping into vacuum pressure lacquer and high temperature solidifying. It is low power consumption and high efficiency.

An intelligent power supply applied to elevator relates to a power electronic topology scheme to adopt high frequency switch energy transformation technology and digitalized phase sequence detection technology to integrate a plurality of (generally 6) components or devices related to elevator assistant power supply in a current elevator control system into a circuit board. Power transformation canbe obtained all by changing high frequency transformer switches, the phase sequence protection can be realized by software, DC band-type brake is subject to rated incitation (110V or 200V), reduced rate maintenance (80V / 160V), thus saving contactor and access of power resistance, simplifying circuit, reducing energy consumption and improving reliability. The 220V power required by the elevator toseparate from the grid can also be obtained by high frequency transformation, thus greatly reducing volume and idle loss, and fully electronizing and intelligentizing the plurality of (generally 6) components in the current system with no contact points, weight / volume being 20-30% of the original weight / volume and cost being around half of the original cost, saving quantities of copper, saving energy consumption (no energy consumption resistance), really realizing integration of intelligence and environment protection, decoupling all the parts, and totally not influencing other circuits by cutting out solely when short pass occurs to a gate machine circuit.

The invention relates to the technical field of motor manufacture, in particular to a method for manufacturing an amorphous alloy stator iron core of a high-frequency motor. The method comprises the following steps of: sufficiently and uniformly mixing amorphous alloy powder and an adhesive, wherein conventional amorphous alloy powder is used as a raw material of the stator iron core; and putting the amorphous alloy powder mixed with the adhesive in a die for pressure forming, wherein the amorphous alloy powder and the adhesive are mixed by a proportion of (100:5)-(100:20), the adhesive is prepared from insulating materials such as epoxy resin, and the like, the temperature for mixing the amorphous alloy powder and the adhesive is 120-180 DEG C, pressure in the pressure forming process is70-90MPA, and the pressure maintaining time in the pressure forming process is 5-10 minutes. The invention has the advantages of simple and convenient manufacture, good product consistency and stability and benefit to mass production. Eddy-current loss, no-load loss and magnetic hysteresis loss which are caused by the stator iron core are greatly reduced while working under a high frequency, thereby the purposes of energy saving and high efficiency are achieved.

A high-temperature superconductive flywheel energy storage system based on permanent magnetic drive comprises a drive part, a superconductive magnetic shielding mechanism and an energy storage part. The drive part, the superconductive magnetic shielding mechanism and the energy storage part are vertically and sequentially arranged in the axial direction. The superconductive magnetic shielding mechanism and the energy storage part are located in a seal cavity (3), the drive part is located outside the seal cavity (3), and the energy storage part is isolated from the drive part. The seal cavity (3) can provide a vacuum environment for the energy storage part. The drive part provides energy for the energy storage part. The superconductive magnetic shielding mechanism is a switch starting or stopping energy input and enabling magnetic field coupling between a permanent magnet disc of the drive part and a metal disc of the energy storage part to be communicated or separated. The end face of the superconductive magnetic shielding mechanism keeps parallel and coaxial with the end face of the permanent magnet disc of the drive part and the metal disc of the energy storage part. The energy storage part stores energy transmitted by the drive part, and a high-temperature superconductive bearing of the energy storage part comprises a permanent magnet rotor and a superconductive stator.

The invention provides a pure motor driving system which includes a battery pack, a gear box and a main drive motor; the battery pack supplies power to the main drive motor; the main drive motor inputs a power to the gear box; wherein, the main drive motor includes a first main drive motor and a second main drive motor. As the two main drive motors with relative lower power are adopted for replacing the existing main drive motor with a large power, therefore, the pure motor driving system can effectively solve the problems that the main drive motor with a large power can not be arranged as the space of a front cabin is not enough and is difficultly designed; devices with large power are difficultly designed and selected; the main drive motor with a large power affects the balance of the integral car, etc.

The invention discloses a method and a device for intelligently switching on and off a transformer set, and belongs to the field of intelligent power equipment. The method is characterized by comprising the following steps of: (1) determining the number N of the transformers according to the multiple relationship of maximum load and minimum load, and connecting the N transformers with equal capacitance and equal impedance in parallel to form the transformer set; (2) acquiring real-time electrical parameters by using a data acquisition unit which is arranged on a primary side of the transformer set when the transformer set runs; (3) computing the rated electrical parameters of the used transformers in the transformer set, and computing, comparing and analyzing the real-time electrical parameters and the rated electrical parameters; and (4) inputting the result of the computing, comparison and analysis into a central processing unit, switching on and off the standby transformers in the transformer set by an actuating mechanism which is operated and controlled by the central processing unit according to the result, and cutting off the input standby transformer in advance when the load is reduced. The method and the device are suitable for a place where the load is changed largely, and have the advantages of saving no-load and load loss, reducing outage maintenance, and improving the reliability of power supply.

The invention discloses a structure of a non-crystal alloy dry type transformer and a method for manufacturing the same. The transformer comprises a three-phase non-crystalline alloy iron core, high and low voltage coils sleeved on iron core columns and upper clamping pieces arranged on the upper ends of the high and low voltage coils, and the transformer also comprises an insulation framework sleeved on the iron core columns and a plurality of aluminum-copper transition connectors fixed on the upper clamping pieces through insulated conducting wire clamps or insulators. The aluminum foil is used as a conducting material of the low voltage coils and wound on the insulated framework, and the head ends and the tail ends of the low voltage coils are fixedly connected with the aluminum-copper transition connectors respectively; and the high voltage coils are wound by copper conducting wires and sealed by epoxy resin, and are sleeved outside the low voltage coils. In the technical proposal, aluminum replaces copper, so that the transformer has the characteristic of low no-load loss of common non-crystalline alloy distribution transformer, and the transformer also has the advantages that the transformer has low material cost and light weight, and minimizes the influence of copper price raising on cost of the non-crystalline alloy distribution transformer, and lowers consumption of insufficient copper resources and the like.

The invention discloses a hydrodynamic retarder with a front stator. The retarder comprises a retarder shaft, a front bearing, a stator, a rotor, a stator end cover, a body, a separation spring, an annular piston, a meshing gear, a locking sliding framework, a return spring, a synchronous locking ring, a needle roller bearing, an outer oil seal and the like, wherein a high-pressure oil outlet cavity B is closed by the stator and the stator end cover, a low-pressure oil inlet cavity A is formed by closing the retarder shaft; the stator is arranged in front of the rotor, the rotor is arranged behind the stator, and the stator and the rotor are arranged in a closed cavity in the body; a sealing ring is arranged between the rotor and the stator and is used for isolating a working cavity C fromthe oil inlet cavity A; when no load exists, a meshing gear is pushed by a separation spring to move rightwards to a right positioning dead point, the meshing gear is separated from the rotor, the rotor does not rotate with the shaft any more, and thereby no-load loss can be caused even though a small amount of media exist in the working cavity C; an oil duct is arranged in front of the stator, the radial size is reduced, and interference with a transmission shaft is avoided. The retarder is advantaged in that the weight is reduced to the maximum extent, noise is reduced, strength and reliability are improved, and no-load loss is reduced.

The invention discloses an economical operation control method for distribution transformers with a spare power automatic switching function. A distribution network system has three operation modes. When the distribution network system is in the control mode, power failure conditions of low-voltage sides of two transformers are detected first, and a relay is used for collecting on-off states of three phases of breakers on the low-voltage sides of the transformers; when any two phases are powered off or the three phases are all powered off, it is judged that the transformers are in a power failure state; then, switching is conducted according to different power failure conditions. In the switching process, firstly, a load is removed from the low voltage side of an original system; secondly, the high voltage on the other side is put into use, then the low voltage is put into use, and finally the high voltage on the fault side is removed. According to the economical operation control method, 10 KV-0.4 KV power distribution devices are combined to be an integral whole and controlled, so that the control difficulty is reduced; switching of the distribution transformers is automatically achieved according to built-in logical functions, so that no-load loss of the transformers is reduced, and economical operation is achieved. The reliability of no-voltage judgment is improved through multi-phase voltage detection, no-voltage faults can be detected more effectively, the quality of electric energy is improved, and the security of electric equipment is protected.

The invention discloses a resin insulation dry type transformer with a three-dimensional roll iron core. The resin insulation dry type transformer comprises a transformer base, an upper clamping part, a lower clamping part and a three-dimensional roll iron core, wherein the upper clamping part and the lower clamping part are correspondingly arranged on the transformer base up and down, and the three-dimensional roll iron core is clamped between the upper clamping part and the lower clamping part; the three-dimensional roll iron core comprises three single frames, the middle parts of the single frames are hollowed out, and the single frames are of rounded rectangle structures in shape; the three single frames are arranged and spliced together in an equilateral triangle shape three-dimensionally; each single frame is formed by continuously winding a plurality of silicon steel trapezoid material straps in sequence; a coil is wound at the joint of every two single frames respectively; each coil is integrally poured by a curing agent and is formed through heating curing; and the exterior of each coil is encapsulated by epoxy resin respectively. The resin insulation dry type transformer is provided with the three-dimensional roll iron core, and has the characteristics of energy conservation and material saving, low no-load loss, low no-load current, low noise, good electrical performance, low partial discharge value, high lightning impulse resistance, high short-circuit resistance and high mechanical strength.

The invention discloses a dry-type transformer for photovoltaic power generation and a photovoltaic inversion system. The dry-type transformer comprises main iron cores, low-voltage coils, leakage reactance iron cores and high-voltage coils; the upper / lower portions, protruding out of the low-voltage coils, of the main iron cores are provided with first clamping pieces respectively, and cross-core threaded rods penetrate through the first clamping pieces and the upper / lower portions of the main iron cores to fix the main iron cores; the upper / lower portions, protruding out of the high-voltage coils, of the leakage reactance iron cores are provided with second clamping pieces respectively, and side threaded rods penetrate through the second clamping pieces and the first clamping pieces to fix the leakage reactance iron cores and the main iron cores in the horizontal direction; the tops and the bottoms of the main iron cores and the leakage reactance iron cores are provided with top fixing plates and bottom fixing plates which stretch across the first clamping pieces and the second clamping pieces respectively, and the top fixing plates and the bottom fixing plates are connected through multiple vertical threaded rods to fix the main iron cores and the leakage reactance iron cores in the vertical direction; the side threaded rods, the top fixing plates and the bottom fixing plates are all coated with insulating layers, so that only a little metal connection is kept between the main iron cores and the leakage reactance iron cores, and the rest parts are all insulated.

The invention relates to a method for reducing no-load loss of an inverter with a two-stage structure. The method is characterized in that a front-stage direct current-direct current (DC-DC) conversion circuit of the inverter with the two-stage structure converts an input voltage Uin into an intermediate DC bus-bar voltage Ubus, and a back-stage direct current-alternate current (DC-AC) inversion circuit reconverts the intermediate DC bus-bar voltage Ubus into an expected output voltage Uo; and a detection circuit is used for detecting the voltage Ubus and the output current Io signal of the inversion circuit and judging by combining a set minimum bus-bar voltage Ubus_min and a rated bus-bar voltage Ubus_nom to control the front-stage DC-DC conversion circuit to work or stop working so as to ensure that the bus voltage Ubus works between the Ubus_min and the Ubus_nom and the front-stage DC-DC conversion circuit obtains higher working efficiency, thereby finally achieving the purpose of reducing the no-load loss of the whole inverter. The method is suitable for the control of reducing the no-load loss of the inverter with the two-stage structure.

The invention discloses a capacity-adjusting transformer suitable for clear seasonal or periodical load changes. The capacity-adjusting transformer comprises a high-voltage winding and a low-voltage winding; the high-voltage winding and the low-voltage winding each comprise two to six series-parallel sections and a common section; when the transformer runs at the high-capacity tap position, the series-parallel sections of the high-voltage winding and the low-voltage winding are respectively connected in parallel to be connected with one parts of the corresponding common sections in series for running; when the transformer runs at the low-capacity tap position, the series-parallel sections of the high-voltage winding and the low-voltage winding are respectively connected in series to be connected with windings of the tapped positions of the corresponding common sections in series for running. According to the capacity-adjusting transformer, the difference between the rated capacity at the high-capacity tap position and the rated capacity at the low-capacity tap position of the transformer is large, and the capacity-adjusting transformer is more suitable for areas with large load differences; no-load loss reduction is large, so that when the capacity-adjusting transformer is applied to the areas with large load differences, the energy saving effect is more remarkable, and the unbalanced load bearing capacity of the transformer is improved; when loads are lower than the rated capacity at the low-capacity tap position, the transformer can run at the low-capacity tap position, and full-capacity running can be achieved at the low-capacity tap position of the transformer.

The invention relates to a power transformer based on the modular combination. A double-arc-shaped roll-core element of each phase of a three-phase three-dimensional roll-core comprises two straight line parts and two arc-shaped parts which are in end-to-end alternate connection, an open / closed yoke structure is arranged on each double-arc-shaped roll-core element and used for nesting a winding of the corresponding phase, and the six straight line parts of the three roll-core elements are bonded to one another respectively to form three iron columns of a three-phase three-column three-dimensional structure. An integrated low-voltage winding and a high-voltage foil winding are nested from inside to outside on each iron column, and each high-voltage foil winding consists of a group of high-voltage foil winding modules which are in series connection. The power transformer adopts the three-dimensional roll-core structure which has the novel double-arc shape and is formed by staggered open / closed yoke structures, and has the advantages of high overall stability, low noise, high operating safety, economic benefit and high reliability. Besides, the whole machine is diversified by the winding modules of fewer types, and the winding modules can be provided by different factories, are easy for on-site defect inspection and convenient for dismounting, replacing and recycling, and can meet the requirements for environmental protection and circular economy to the greatest extent.

The invention relates to an amorphous alloy delta transformer core. The amorphous alloy delta transformer core is formed by vertically butting three identical core columns with upper and lower yokes, wherein the core columns are formed by winding amorphous alloy strips, and the cross section of each core column is circular; and the upper and lower yokes are identical triangular frames formed by winding amorphous alloy strips equal in width. A transformer manufactured from the amorphous alloy delta transformer core has the advantages of small iron loss, low noise, less material consumption, good short circuit impact property and the like.