110 results about "Variable-frequency transformer" patented technology

The invention discloses an electric field coupled power transfer system and a control method based on the novel topology. The system comprises a high-frequency inverter, a high-frequency resonator, an electric field coupling mechanism and an electric energy conversion link, and is characterized in that the high-frequency inverter is a double-E type amplifying high-frequency inverter, a high-frequency transformer is arranged between the high-frequency inverter and the high-frequency resonator, the high-frequency resonator is further connected with a controller, and the output end of the controller is connected with an inductance compensation tuning module and a drive circuit. The electric field coupled power transfer system has the obvious effects that the high-frequency voltage at the two ends of a coupling mechanism is increased, the strength of an electric field is enhanced, the transmission distance is lengthened, the voltage at the two ends of a high-frequency switch tube is increased to meet the requirement of high-frequency power electronic devices at the present stage, the power capacity of the system is improved, the voltage of the switch tube is reduced, the switch loss is reduced, and the adaptive ability of the system is improved.

The invention discloses a method, device and system for inhibiting the low-frequency oscillation of a power system. The method comprises the following steps: determining a system transfer function of an interconnected power system section of a variable-frequency transformer (VFT); determining parameters of a damping controller in accordance with the system transfer function; and using the VFT to inhibit the low-frequency oscillation of the power system based on the parameters of the damping controller. In the method, device and system for inhibiting the low-frequency oscillation of a power system, the control objective is definite, and the parameters of the damping controller can be adjusted in time by simply tracking the response of an analytic system to the turbulence without learning about the specific structure and parameters of the system or solving complicated power system equations. Thus, the invention achieves a favorable effect on inhibiting the low-frequency oscillation in the system, thereby being beneficial to promoting the security and stability of the power grid.

The invention discloses a variable speed wind-power system based on a variable frequency transformer and a control method of the variable speed wind-power system. The variable speed wind-power system comprises a cage type wind-power unit group, a variable frequency AC bus, a booster transformer, a high voltage transmission line, a step down transformer, a variable frequency transformer and a power frequency power grid, wherein a variable frequency AC sent by the cage type wind-power unit group is collected to the variable frequency AC bus, the variable frequency AC subjected to voltage reduction of the step down transformer enters the variable frequency transformer, the variable frequency transformer converts the variable frequency AC into power frequency AC, and the power frequency AC is injected into the power frequency power grid. According to the variable speed wind-power system based on the variable frequency transformer, the single-machine capacity of the wind-power unit group can be increased, the failure rate of the wind-power unit group is reduced, the maintenance work is reduced, the effective power generation time is increased, the wind energy utilization rate can be increased, and mechanical stress and output power fluctuation are decreased. The control method is simple in control and is convenient for operation.

The invention discloses a power electronic transformer based on simple PFC (Power Factor Correction). All single phase structures in a three-phase circuit are same and independent to each other, wherein each phase comprises an input grade, an isolation grade and an output grade; input ends of an input-grade power transformer group and an output-grade power transformer group of each single phase are connected in a star shape; the input grade of each single phase adopts a series connection way; the input-grade power transformer group comprises a diode bridge-type circuit and a buck circuit and can realize the control of a power factor, and the alternating side of each power transformer group is connected in parallel with a pressure sensitive resistor; the isolation grade comprises a high-frequency DC / AC, a high-frequency transformer and a high-frequency AC / DC link, wherein a primary edge of the high-frequency transformer is connected in series with a capacitor, and the loss consumption of a switch tube is reduced under the action of a resonance soft switch; an output side of the isolation grade adopts a parallel connection way; and the output-grade power transformer group adopts a bridge-type inverting circuit, and an output side of the output-grade power transformer group is also connected with a filter. The invention has the advantages of simplifying the circuit structure, reducing the cost, realizing the power factor correction and resonance soft switch and increasing the conversion efficiency.

The invention provides a measuring method for the stray capacitance of a large-capacity high-frequency transformer. The method includes the steps that 1, a frequency-variable excitation signal is exerted on the high-frequency transformer through a signal generator, and an oscilloscope collects a voltage signal and a current signal of a primary-side winding of the high-frequency transformer; 2, the natural resonant frequency of the high-frequency transformer is acquired according to Lissajous figures, displayed by the oscilloscope, of the voltage signal and the current signal; 3, the magnetic inductance Lm of the primary-side winding of the high-frequency transformer and the leakage inductance Ls of a secondary-side winding of the high-frequency transformer are calculated; 4, the stray capacitance of the high-frequency transformer is calculated. Compared with the prior art, no precision equipment such as an impedance analyzer and a network analyzer is needed, the stray capacitance of the large-capacity high-frequency transformer can be conveniently and effectively extracted through simple voltage and current measurement, and research on the stray parameter effect of the large-capacity high-frequency transformer and improvement on the broadband frequency characteristics of the large-capacity high-frequency transformer are facilitated.

The invention relates to a uterine cavity microwave treatment device for the obstetrics and gynecology department, which belongs to the technical field of medical equipment. According to the technical scheme adopted, the uterine cavity microwave treatment device comprises a device body and a microwave massage cover; a variable-frequency transformer chamber is internally provided with an E-type variable-frequency coil, the microwave massage cover is internally provided with a massage layer, a massage roller is arranged in the massage layer, and the lower side of the massage roller is provided with a microwave channel opening; a microwave reaction device is arranged inside the device body, and the microwave reaction device is internally provided with a reaction layer; the outer side of a carbon rod is provided with a magnetic induction coil; an external conveying cylinder is arranged at the right side of the microwave reaction device, and a microwave amplifier is arranged inside the external conveying cylinder; and the front side of the microwave reaction device is provided with wiring contacts. The uterine cavity microwave treatment device for the obstetrics and gynecology department is fully functional and easy to use, saves time and labor in uterine cavity microwave treatment recovery of patients, is scientific and convenient, and safe and efficient, and reduces the work difficulty of medical staff.

The invention provides a novel variable-speed salient-pole synchronous motor and a huge rotary frequency converter. The novel variable-speed salient-pole synchronous motor belongs to the category of motor principle, characteristic and structure; the huge rotary frequency converter belongs to novel flexible alternating-current power transmission technology, relating to a variable frequency transformer (VFT). The problems to be solved in the invention are as follows: realization of variable speed and constant frequency of the salient-pole synchronous motor, realization of the asynchronous running of the synchronous motor, and realization of the rotary frequency conversion. The stator of the novel variable-speed salient-pole synchronous motor is identical with the normal alternating-current motor stator; the rotor is m-phase (m is generally equal to 3) p pairs salient-pole magnetic poles, wherein m is a positive integer more than 1. The magnetic pole winding of the rotor is spatially distributed by the electric angle of 360 degrees / m and is the alternating-current excitation and variable-frequency power supply excitation with the electric angle of 360 degrees / m referring to time. As to the magnetic passage, the p pairs of salient-pole magnetic poles of the rotor can adopt a shunted or cascaded magnetic passage mode; and the shunted mode is preferably selected. The novel variable-speed salient-pole synchronous motor and the huge rotary frequency converter are cores of a huge variable-frequency transformer, a novel large variable-speed hydroelectric generating set and a wind power generating set and systems thereof, and are a fundamental original innovative invention.

The application discloses a fault ride-through control method for a variable-frequency transformer, which comprises the following steps: first, obtaining the voltage of a first grid, the voltage of asecond grid, the voltage of a stator and the current of the stator; then, calculating the voltage reference value corresponding to a single series three-phase converter after preprocessing; and finally, converting the voltage reference value into a control signal to control the series three-phase converter. The negative sequence voltage and negative sequence current of the stator caused by the negative sequence voltage of the first grid can be restrained, and the torque and power fluctuation of double rotor angular speed and double stator synchronization speed can be eliminated. The negative sequence current of the stator caused by the negative sequence voltage of the second grid can be restrained, and the electromagnetic torque and power fluctuation of double rotor synchronization speed can be greatly reduced. That is to say, the voltage imbalance problems of the left and right grids are solved at the same time by using a single series three-phase converter. Moreover, the grid cost isreduced. The application also discloses a fault ride-through control device, a circuit controller and a computer readable storage medium, which have the same beneficial effects.

The invention relates to a fractional frequency transmission wind power generation system and method based on an isolation type variable frequency transformer. The isolation type variable frequency transformer is of concentrated variable frequency of a wind power plant, and variable speed operation and maximum power tracking of a whole wind power generation set are realized, so that a frequency converter does not need to be configured for each single wind power generation set, the technology is applied to wind power generation, the system can be simplified greatly, the reliability is improved,only small converter capacity is needed, the system has the advantages of fractional frequency transmission in the aspect of long-distance power transmission, and the system is particularly applicable for offshore wind power with far offshore distance. The invention discloses a novel wind power system scheme, a starting method under the system scheme, and a maximum power tracking control method.Compared with the prior art, the system has the advantages of low cost, high reliability, high stability, few harmonic waves inside a wind power plant and the like.

The invention discloses a PSO (Particle Swarm Optimization)-based maximum wind energy capturing method of a VSVF (Variable-speed Variable-frequency) wind power system. Aiming at the VSVF wind power system which is formed by a variable-frequency transformer and multiple parallel-running permanent magnetic synchronous wind power generation units, cooperative optimization can be carried out on the rotating speed of the variable-frequency transformer and the pitch angles of all permanent magnetic synchronous wind power generation units through PSO, so that the capturing of maximum wind energy of the VSVF wind power system is realized. Compared with a univariate optimization method aiming at the rotating speed of the variable-frequency transformer, a PSO-based multivariate optimization method provided by the invention is capable of obtaining more wind energy.

Systems and methods are provided that include a gas turbine, a generator coupled to the gas turbine and configured to generate a first electrical power output, and a variable frequency transformer coupled to the generator and configured to be coupled to an electrical grid such that the variable frequency transformer is configured to transform the first electrical power output into a second electrical power output having one or more power characteristics that correspond to the electrical grid.

A variable frequency transformer including: a first parallel circuit including at least two of the rotary transformers arranged in parallel and having an isolating circuit breaker connected to a rotor winding of each of the rotary transformers, and a separate synchronizing circuit breaker connected to a stator winding in each of the rotary transformers in the first parallel circuit; a first main transformer having a first winding connectable to a first power grid and a secondary winding connectable to the isolating circuit breaker in the first parallel circuit; a second main transformer having a first winding connectable to a second power grid and a secondary winding connectable to each of the synchronizing circuit breakers in the first parallel circuit, and a control system operatively connected to each of the synchronizing circuit breakers, the isolating circuit breakers and the drive motors for each of the rotary transformers.

The invention discloses a variable speed constant frequency and energy storage method and a variable speed constant frequency and energy storage device for wind power generation. A control signal is transmitted through a controller to adjust an excitation power supply, a motor side circuit breaker, a grid-connected switching and monitoring device, a power converter, a first clutch and a second clutch and control the working mode of a wind power generation system to fulfill the aims of variable speed constant frequency and flywheel energy storage of the wind power generation. In addition, the variable speed constant frequency and energy storage device for the wind power generation is provided for finishing the functions. According to the method and the device, a mechanical variable frequency transformer is adopted, and a flywheel energy storage device and the power generation system are organically integrated, so that low-voltage ride-through is easy to realize, the hardware structure of the system is simplified, and the efficiency and the reliability are improved.

A resistance welding high frequency transformer and a high frequency resistance welding machine using the same are disclosed. The transformer comprises a magnetic core (6), primary coils (1, 2, 3) and secondary coils (4, 5). The primary coils and the secondary coils are alternatively positioned layer by layer. Each secondary coil is arranged between two primary coils. The primary coils are provided at the internal side and the external side of the secondary coil. The secondary coil is composed of red copper pipes through which water flows. Each secondary coil is wound with one to two turns. The red copper pipes of the secondary coils and rectifier diodes constitute a full-wave rectifier circuit. The resistance welding high frequency transformer can be wound conveniently. Its structure can reduce size, weight, leakage inductance and copper circuit loss, and the heat from the primary coils and secondary coils is dissipated conveniently, thus enabling the high-frequency transformer to output high current and high power with a high duty cycle. The resistance welding machine using the transformer has high power factor, high output power, small volume, light weight, and saves energy and material, which is especially suitable to produce a suspension spot welding machine with the integration of the transformer and welding tongs.

A frequency converter used in temperature rising test of motor is connected in series between power supply and motor to be tested .It features that two sine voltage superposition is contained in basic composition of frequency transformer output voltage.

The invention discloses a method for calculating the iron consumption resistance of a variable frequency motor undera PWM (Pulse-Width Modulation) harmonic condition, which belongs to the field of loss analysis and calculation of an alternating current motor and is used for expressing the iron consumption resistance of an induction motor as a function of induction potential and rotating speed on the basis of a segmented variable coefficient iron consumption model. According to the method, additional iron loss generated by harmonic waves of the PWM frequency converter and surface and pulse vibration loss generated by space harmonic waves of the motor are considered. By using the method provided by the invention, the accurate variable frequency motor equivalent circuit under the condition ofconsidering the iron loss can be obtained. Finally, taking a 5.5 kW variable-frequency induction motor and a 30 kW variable-frequency induction motor as examples, and the change rule of the iron consumption resistance of the variable-frequency induction motors is obtained. Tthe two induction motors are used for verifying the effectiveness of the device.

The invention discloses a control method of variable frequency transformer fault ride-through circuit, and the related circuit. The control method of variable frequency transformer fault ride-throughcircuit includes the steps: preprocessing the acquired power grid voltage, the stator interface voltage and the rotor interface voltage to obtain the stator voltage direct current component and the rotor voltage direct current component, and obtaining the first power grid voltage frequency and the second power grid voltage frequency through detection and processing by means of a digital phase-locked loop; performing reference voltage calculation processing on the stator voltage direct current component, the rotor voltage direct current component, the first power grid voltage frequency and thesecond power grid voltage frequency to obtain the voltage reference value of a first PWM transformer and the voltage reference value of a second PWM transformer; and performing control signal acquisition processing on the voltage reference values to obtain switch signals of controlling the first PWM transformer and the second PWM transformer. When the asymmetric fault of the power grid voltage occurs, the control method of variable frequency transformer fault ride-through circuit performs voltage compensation to solve the asymmetric fault of power grid voltage so as to prevent propagating of the asymmetric fault of voltage.

The invention discloses a method for designing an auxiliary winding of a switching power supply high-frequency transformer to inhibit common-mode electromagnetic interference (EMI). According to the method, by a measure of reasonably designing an anti-phase auxiliary winding on the primary side of the transformer, the common-mode conducted EMI of a switching power supply is inhibited in high performance. The anti-phase auxiliary winding connected in parallel with a primary winding of the transformer is designed according to a zero equipotential line theory, an electric field generated by the anti-phase auxiliary winding eliminates common-mode noise voltage of primary and secondary windings, and common-mode conducted EMI noise caused by a coupling capacitor between the primary winding and the secondary winding of the transformer is effectively inhibited. According to the method, the common-mode conducted EMI noise is effectively inhibited, the loss of the switching power supply for the transformer is effectively reduced, the volume of the power supply can be greatly reduced and the energy conversion efficiency is improved.

The invention relates to a direct current supply used for checking a large current transformer. The direct current supply is characterized in that four parts, namely, a full-controlled rectifier module, an inverse module, a high-frequency transformer and an uncontrolled rectifier module are included; the four parts are electrically connected sequentially; the inverse module is connected in parallel with a primary side of the high-frequency transformer; and a secondary side of the high-frequency transformer is connected in parallel with an AC side of the uncontrolled rectifier module. The direct current supply ensures that the ripple coefficient of the output current is less than 0.5 percent, the output current is continuously adjustable in a wide range, the volume and the weight are reduced, the cost is lowered greatly, and the requirements for checking the large current transformer in an electric power system can be satisfied at the same time.

The invention discloses an automatically resonance compensable inductive power transmission system for multiple primary coils. The inductive power transmission system for the two primary coils has the structural characteristics that a high-frequency transformer accesses an energy transmitting part circuit, so that a primary winding of the first high-frequency transformer (L12) is connected with a heteronymous end of the first primary coil in series, a secondary winding of the first high-frequency transformer (L12) is connected with the heteronymous end of the second primary coil in series, and thus mutual inductances between the first and second primary coils are counteracted. According to the system, when a single inverter breaks down or stops working, the non-faulty inverter still works at a resonant state, and a power factor of the system is high, and safe and economic operation of a power grid is not influenced.

The invention discloses a variable frequency transformer (VFT) control system, relating to the variable frequency transformer technology field. The control system comprises a trigger angle control unit which determines a trigger angle according to rotating speed of a rotor, command torque and measurement torque; a rectifying device which adjusts output voltage according to the trigger angle; a direct current motor which can be in coaxial arrangement with the rotor and determines output torque according to the output voltage from the rectifying device. The invention discloses a three-level control system of a VFT device, an apparatus and a system, provides a variable frequency transformer control system whole block diagram, establishes a VFT direct current motor driving system comprising a rectification trigger loop, researches and designs concrete control block diagrams and key parameters of main functions of VFT bottom layer trigger angle control, middle layer convey power control, high layer system application control the like, and establishes a base for realizing various functions of a variable frequency transformer.

The invention discloses an adjustable multi-functional power supply, comprising a capacitor voltage-adjusting circuit, an auxiliary power circuit, a reverse-phase switch signal generation circuit, a rectifier filter circuit and an alarming circuit. The adjustable multi-functional power supply is characterized in that the power supply also comprises a controllable silicon voltage-adjusting circuit, a triode voltage-adjusting circuit, a reverse-phase switch signal amplification circuit, a reverse-phase switch circuit, a frequency conversion transformer load circuit, a self-adaptive filter circuit, a self-adaptive voltage-adjusting circuit by sequentially reducing the voltage, a DC voltage current synthesis circuit, a DC output voltage current sampling circuit, a sampling signal amplification circuit and an amplification sampling signal control circuit. The adjustable multifunctional power supply also comprises a DC over-voltage over-current alarming circuit. The adjustable multi-functional power supply designs the adjustable AC power supply to the parallel circuit of the capacitor voltage-adjusting circuit, the controllable silicon voltage-adjusting circuit and the triode voltage-adjusting circuit, leads the non-sinusoidal characteristic of the controllable silicon voltage-adjusting circuit to be compensated and has the characteristic of large power simultaneously. The adjustable multi-functional power supply has the advantages that the input voltage and the output voltage are continuous and adjustable, the power is large and the waveform is excellent.

The invention relates to a torque and power fluctuation suppression method of a variable-frequency transformer. The method comprises the steps of S1, collecting related signals; S2, processing the related signals to obtain a stator side power grid positive sequence voltage direct current component, a stator voltage direct current component and a current direct current component; S3, processing according to a preset voltage control equation to obtain direct-current components of all voltage reference values of a series three-phase converter; S4, carrying out coordinate transformation processingto obtain voltage reference values of the series three-phase converter, and adding the voltage reference values of the series three-phase converter to obtainthe voltage reference value of the seriesthree-phase converter in a two-phase static coordinate system; and S5, carrying out space vector modulation on the voltage reference value of the series three-phase converter to obtain a control signal of a switch of the series three-phase converter, and inputting the control signal into a controller to realize suppression of a torque and a power fluctuation of the variablefrequency transformer. In the invention, the variable frequency transformer has a capability of operating under bilateral imbalance and a harmonic power grid voltage.

The invention relates to a dynamic frequency division wind power generation system with autonomous inertia response. The system comprises a wind power plant, a wind power plant step-up transformer, alow-frequency alternating-current power transmission line, a power transmission step-down transformer, a winding rotor asynchronous motor, an electric excitation synchronous motor, an excitation system and a control unit thereof, a coupling unit, a double-alternating-current-port frequency converter, a frequency converter controller, a grid-connected device, switching equipment, a step-down transformer, a starting resistor, a detection unit and a central controller. Compared with the systems in the prior art, the synchronous motor in the isolated variable-frequency transformer is used as the power grid interface and the whole system shows the characteristics of the synchronous generator for the power grid and facilitates stable operation of the system. In addition, after the whole system is started, the winding rotor asynchronous motor provides centralized frequency conversion for the wind power plant under the control of the dual-port alternating-current frequency converter, the converged electric energy of the wind power plant drags the electrically excited synchronous motor to operate at the synchronous rotating speed and the characteristic of power grid friendliness is achievedunder the cooperation of the excitation system and the control unit of the excitation system.

The present invention relates to a real-time detection method of lubricating oil for vehicle and ship and its detection equipment. It is characterized by that a capacitance transducer can be placed into the lubricating oil for vehicle and ship, two electrodes of the capacitance transducer are respectively connected with current meter or capacity meter and varying-voltage frequency converter, and a voltage meter is parallel-connected between two electodes of the capacitance transducer, and the change of voltage and frequency of the varying-voltage frequency converter is controlled by a control device. Said conrol device can make the varying-voltage frequency converter voltage or frequency produce change to measure changed values of current, voltage or capacitance to obtain additive consumption.

A fault ride-through circuit with a variable frequency transformer (VFT) and a control method thereof are provided, and the control method comprises: pretreating acquired voltages of grids, a voltage of a stator interface and a voltage of a rotor interface to obtain a rotor voltage DC component and a rotor voltage DC component; testing and treating a voltage frequency of a first grid and a voltage frequency of a second grid; carrying out a reference voltage calculation for a stator voltage DC component, a rotor voltage DC component, the voltage frequencies of the first grid and the second grid to obtain a positive voltage reference value of the first PWM convertor and the second PWM convertor, and processing the voltage reference values to obtain the switch signals for controlling the first PWM convertor and the second PWM convertor.

The invention belongs to the technical field of flexible direct-current power distribution system fault positioning, and particularly relates to a DAB type direct-current converter high-frequency impedance equivalent modeling method, which comprises the following steps of analyzing a single DAB module in a DAB type direct-current converter, enabling a switching device to be equivalent to a resistor element, and ignoring the influence of a switching process; using a step signal generated during system failure as a high-frequency source, analyzing a high-frequency impedance loop of the DC converter after failure, and obtaining a high-frequency impedance expression of the DC converter through derivation. The method specifically comprises the steps of firstly, enabling a high-frequency transformer in a loop to be equivalent, converting the parameters to a high-voltage side, and establishing a relational expression of voltage and current between two coupling coils of the transformer; and according to the structure and parameters of the high-frequency transformer, deducing each circuit parameter in the T-shaped equivalent circuit of the transformer, and converting the circuit parametersto a high-voltage side to obtain the equivalent circuit of the transformer. According to the method, the nonlinear characteristic of a system caused by a power electronic device is solved, and the obtained model has the very high precision.

The invention discloses a method for adjusting leakage inductance of a high-frequency transformer and the high-frequency transformer. The high-frequency transformer comprises a magnetic core, a primary winding, a secondary winding and one or two high-frequency magnetic strips, wherein the high-frequency magnetic strips are distributed between the primary winding and the secondary winding and arranged on the external side of a magnetic core window of the high-frequency transformer; and the high-frequency magnetic strips are arranged on two sides of the magnetic core when two high-frequency magnetic strips are adopted. The high-frequency magnetic strips are inserted into the transformer to achieve the aim of integrating resonance inductors into the transformer. The size of the resonance inductors can be adjusted by controlling the gap between the high-frequency magnetic strips and the magnetic core. Compared with the prior art, one resonance inductor can be reduced for reducing the cost, and the high-frequency transformer is small in size, strong in magnetic coupling, small in electromagnetic interference, high in transmission efficiency, convenient to manufacture and strong in generality.

The invention relates to a fault ride-through control method of a variable frequency transformer. According to the invention, by controlling the output voltage of a series three-phase converter, the method has the following effects that (1) stator harmonic voltage and stator harmonic current caused by stator side power grid harmonic voltage are suppressed, so that six-time rotor rotating electrical angular speed, six-time stator synchronous angular speed, twelve-time stator synchronous angular speed and torque and power fluctuation of the six-time stator synchronous angular speed and a six-time rotor synchronous angular speed are eliminated; and (2) the stator harmonic current caused by the rotor side power grid harmonic voltage is suppressed, so that the torque and power fluctuation of the six-time rotor synchronous angular speed are greatly reduced. According to the invention, the variable-frequency transformer is enabled to have the capability of operating under the voltage of the bilateral harmonic power grid under the condition of not adding any equipment.