214 results about "Constant frequency" patented technology

The invention provides a wind storage frequency modulation control method and device based on virtual inertia support and a medium, and the method comprises the steps: carrying out the aggregation of wind turbine generators through employing an equivalent model, and obtaining the virtual inertia of a wind power plant and the inertia of an energy storage power station; detecting system frequency deviation by introducing frequency tracking negative feedback, and calculating required auxiliary power according to power grid frequency deviation by utilizing inertia response characteristics of wind energy storage; the wind turbine generator releases kinetic energy of a rotor of the wind turbine generator to provide inertia support required by the system; through the design of the energy storage controller, the energy storage system adapts to the operation condition of new energy, necessary inertia support is provided for the system, charging and discharging of the storage battery are controlled, real-time response is achieved, power balance is maintained, and then constant frequency control is achieved. According to the invention, an efficient and integrated control system is constructed, and the flexibility and response speed of the wind energy storage system to cope with power grid frequency fluctuation challenges are greatly improved.

The invention discloses a three-phase vehicle-mounted charger hierarchical control method and system based on a battery state, and the method comprises the steps: obtaining the battery state data of a vehicle-mounted power battery, the battery state data at least comprising a battery voltage and a battery charge state; determining a charging mode according to the battery voltage and / or the battery charge state; when the charging mode is a first charging mode, controlling the PFC converter to operate in a constant voltage output mode, and executing voltage following control on the bidirectional DC-DC converter based on the battery voltage; and when the charging mode is a second charging mode, executing voltage following control on the PFC converter based on the battery voltage, and controlling the bidirectional DC-DC converter to operate in a constant-frequency or constant-phase output mode at the same time. By setting hierarchical control strategies under different working conditions, the output voltage of the PFC converter is adaptively adjusted, the voltage regulation transformation ratio under different working conditions is optimized, the overall circuit structure is improved, and the charging efficiency of the vehicle-mounted charger within the full working condition range is improved.

The invention belongs to the technical field of inverters, and provides a three-level quasi-fixed-frequency hysteresis comparison inverter and a control method thereof, and the inverter comprises an inverter bridge, a filter inductor and a current transformer which are connected in sequence. Wherein the inverter bridge is arranged between the upper direct-current bus and the lower direct-current bus and adopts a three-phase bridge type structure, each phase bridge type structure at least comprises four power switch tubes and two diodes, a first voltage stabilizing capacitor is arranged between the upper direct-current bus and the midpoint of the inverter bridge, and a second voltage stabilizing capacitor is arranged between the lower direct-current bus and the midpoint of the inverter bridge. A second voltage stabilizing capacitor is arranged between the lower direct current bus and the midpoint of the inverter bridge; a driving unit, a driving control unit, a phase change ring width hysteresis comparator and a ring width calculator which correspond to each phase of bridge type structure are arranged between the inverter bridge and the current transformer, and an inverter output voltage detection unit is arranged between the ring width calculator and the filter inductor. And an inverter output current detection unit is arranged between the phase change ring width hysteresis comparator and the current transformer.

An acceleration voltage measurement circuit outputs an acceleration voltage signal Vacc as a measurement signal in which an acceleration radiofrequency voltage excited in the accelerating cavity is measured. A low power radiofrequency control system inputs, to the accelerating cavity, as radiofrequency power, control radiofrequency power at a constant frequency included in the range of the resonance frequency of the accelerating cavity. When the phase difference between the acceleration voltage signal Vacc and the control radiofrequency power becomes within the predetermined value, the low power radiofrequency control system inputs, to the accelerating cavity, as radiofrequency power by feedback control, the acceleration radiofrequency power synchronized with the acceleration frequency that is the frequency of the acceleration voltage signal Vacc, and thereafter, when the acceleration frequency reaches an output frequency Fext, stops the input of the acceleration radiofrequency power to the accelerating cavity.

The purpose of the present invention is to provide a magnetic resonance imaging apparatus and a method for controlling a refrigerator. The magnetic resonance imaging apparatus increases the operating rate of an MRI apparatus by prolonging the replacement life of the refrigerator and reducing the replacement frequency of the refrigerator. And executing a cold head life prolonging mode. In the cold head life extension mode, regardless of the temperature of the superconducting coil, the displacer of the refrigerator is moved at a constant frequency lower than a predetermined upper limit frequency, and the drive frequency of the compressor drive unit adjusted by the compressor inverter is controlled in accordance with the temperature of the superconducting coil.

The invention provides a micro-grid on-load soft start control method and an energy storage converter parallel system, and relates to the technical field of energy storage converter soft start. The control method comprises the following steps: randomly selecting one energy storage converter as a host, selecting the other energy storage converters as slaves, and sending a soft start instruction to the host by a control unit; and the host broadcasts a soft start instruction to each slave through the data bus. After the host and the slaves receive the soft start instruction, the relays are kept disconnected, constant-voltage and constant-frequency alternating-current soft start is synchronously executed, and the inversion voltage of the relays is constructed. The inverter voltage is detected in real time, and whether the AC soft start is completed is judged according to the inverter voltage; if so, the host broadcasts a relay closing signal to each slave; and closing each relay according to the relay closing signal to finish the on-load soft start of the micro-grid. The structure and the size of the energy storage converter parallel system are simplified, the stability of the micro-grid system is enhanced, and the service life of the micro-grid system is prolonged.

A bioelectrical signal abnormality monitoring method comprises: generating a noise signal having a preset constant frequency; superposing the noise signal onto a right leg drive electrode; using a front-end circuit to preprocess analog signals from a reference electrode and a collecting electrode, and outputting the analog signals to an analog-to-digital converter; using the analog-to-digital converter to convert into digital signals, and transmitting the digital signals to an operation analysis unit; the operation analysis, unit performing band-stop filtering on the digital signals, performing a subtraction operation on the digital signals before and after the band-stop filtering processing to obtain a difference value, storing the difference value in a queue, periodically solving for the RMS of the data in the queue, and based on the RMS and a fitting formula, calculating the impedance of the human body; and judging an electrode connection state according to the impedance of the human body.

The invention discloses a frequency stability control method and system for a network construction type optical storage parallel system containing an electric vehicle load. The method comprises the following steps: generating reference power; obtaining the state of charge (SOC) of an energy storage battery, a three-phase bus voltage instantaneous value # imgabs0 # and the maximum power # imgabs1 # of a photovoltaic panel, and calculating to generate a photovoltaic inverter reference active power # imgabs2 # and an energy storage inverter reference active power # imgabs3 #; calculating instantaneous power; the instantaneous active power # imgabs4 # and the instantaneous reactive power # imgabs5 # of the photovoltaic inverter and the instantaneous active power # imgabs6 # and the instantaneous reactive power # imgabs7 # of the energy storage inverter are calculated respectively; photovoltaic reserved capacity VSG control is carried out; energy storage constant-frequency VSG control is carried out; the system comprises a reference power generation module, an instantaneous power calculation module, a photovoltaic reserved capacity VSG control module, an energy storage constant frequency VSG control module and a PWM modulation module.

The invention relates to a hydraulic station pressure closed-loop energy-saving control system and method.The hydraulic station pressure closed-loop energy-saving control system comprises a PID adjusting controller, a servo motor and a hydraulic pump, a control signal is input into the PID adjusting controller, the PID adjusting controller adjusts the servo motor according to feedback of speed and pressure signals, the adjusted signal is input into the servo motor, and the servo motor is controlled by the PID adjusting controller. The servo motor acts according to the adjusting signal and drives the hydraulic pump to output pressure. A constant-frequency asynchronous motor used at present is replaced by the servo motor, a servo driving system, a pressure feedback sensor and other assemblies are additionally arranged in a matched mode to form a servo variable-speed control system, pressure and flow form double-closed-loop control, on-demand energy supply of the hydraulic pump is achieved, power matching is optimized, and electric energy waste during low-flow work of the hydraulic station is reduced. According to the electro-hydraulic servo control system, pressure and speed double-closed-loop control is adopted, accurate energy supply according to needs is really achieved, shutdown operation can be achieved in the long-time pressure maintaining or intermittent stage, and therefore optimal energy supply is achieved.

The invention relates to the technical field of fine atomization of large-flow liquid, in particular to a multi-sound-source atomization device and method.The multi-sound-source atomization device comprises an ultrasonic output module, a liquid supply module, an ultrasonic transducer multi-sound-source array and a multi-sound-source matching resonance atomization cavity; the ultrasonic output module is used for outputting a high-frequency signal and converting the high-frequency signal into an alternating signal with constant frequency and increased amplitude, the liquid supply module is used for stably outputting liquid drops, the ultrasonic transducer multi-sound-source array is used for converting the alternating signal into a high-frequency large-amplitude ultrasonic signal, and the multi-sound-source matching resonance atomization cavity is used for coupling and superposing the ultrasonic signal. And an enhanced sound field is output to realize superfine atomization of large-flow liquid. According to the multi-sound-source cooperative non-contact atomization device and method, aiming at the atomization scene of large-flow and viscous liquid, the particle size concentration ratio can be guaranteed, meanwhile, the problem of spray hole blockage can be effectively solved, meanwhile, by obtaining higher sound field intensity, fine atomization of the large-flow liquid is achieved, and the atomization efficiency is improved.

The invention provides a stimulation parameter setting device for dyskinesia and an implantable closed-loop stimulation system, and belongs to the technical field of medical instruments. The device comprises a processor, wherein the processor is used for determining a variable-frequency mode or a constant-frequency mode according to the accelerated speed of a patient; when the frequency conversion mode is determined to be adopted, outputting a stimulation signal according to a preset frequency conversion stimulation parameter; and when the constant frequency mode is determined to be adopted, extracting an individual specific biomarker according to the physiological signal, obtaining a target threshold value, and adjusting a stimulation parameter according to a relationship between the individual specific biomarker and the target threshold value. The system comprises a processor and a controller. The controller is used for outputting stimulation signals according to the stimulation parameters.

A method for controlling a direct-current-to-direct-current (DC-to-DC) converter includes (a) causing the DC-to-DC converter to operate in a constant frequency operating mode, (b) determining that a duty cycle of a first switching device of the DC-to-DC converter has crossed a first threshold value, and (c) in response to the duty cycle of the first switching device of the DC-to-DC converter crossing the first threshold value, causing the DC-to-DC converter to reduce switching frequency and switch from operating in the constant frequency operating mode to operating in a constant off-time operating mode.

This application provides a current limiting protection method and system for a variable speed constant frequency device. The method includes: First, the variable speed constant frequency device operates in a constant voltage state during normal operation; Second, it determines whether a hardware overcurrent protection event has occurred. If so, it proceeds to the third step; otherwise, it returns to the first step; Third, it performs a fault reset and automatically restarts the variable speed constant frequency device to operate in a constant current state. Furthermore, after operating in this constant current state, it determines whether the hardware overcurrent protection event is caused by a short circuit, overload, or other temporary sudden anomaly. If it is a short circuit, it maintains a preset current output for a certain duration, allowing the downstream circuit time to switch power and maintain circuit stability. If it is an overload, it performs overload protection and shuts down to prevent circuit damage. If it is neither a short circuit nor an overload, it is generally a temporary sudden anomaly, and it can switch back to operating in a constant voltage state.

The invention discloses a nonlinear support system and a hypersonic velocity sweep / fixed frequency wind tunnel test method, and belongs to the technical field of wind tunnel tests. The device comprises a protection platform, a protection cover, a lifting platform, a vertical mounting plate, a protection cover shoulder split, a test model and a driving mechanism, the test model is mounted at the top of the vertical mounting plate through the driving mechanism, the vertical mounting plate is mounted on the lifting platform, the protection cover is mounted on the protection platform, and the protection cover shoulder split is arranged at the top of the protection cover. The vertical mounting plate and the driving mechanism are arranged in the protective cover; and the test model at the top of the vertical mounting plate extends out of the protective cover shoulder cleft of the protective cover. The technical problem that in an existing hypersonic wind tunnel test, structural nonlinear factors such as gaps, friction and collision between kinematic pairs of an executing mechanism are ignored due to a simplified supporting mode, and consequently the influence of the performance of the executing mechanism in a complex vibration environment cannot be truly reflected by a test result is solved. And a reliable test means is provided for revealing a structural nonlinearity and pneumatic nonlinearity coupling effect rule.

A method of determining a filling level of a product in a tank, comprising the steps of: generating an electromagnetic transmit signal exhibiting a measurement sweep across a time series of piece-wise constant frequencies being within a measurement frequency range starting at a first frequency, and ending at a second frequency higher than the first frequency, a difference between frequencies in each pair of adjacent frequencies in the frequency range being equal to the first frequency; guiding the transmit signal towards and into the product in the tank; guiding an electromagnetic reflection signal back towards the transceiver; mixing the reflection signal with an electromagnetic reference signal, resulting in a mixer output indicative of a difference between the reflection signal and the reference signal; forming a measurement signal based on the mixer output; and determining the filling level based on the measurement signal.

The invention discloses a distributed architecture voltage frequency control method and a distributed architecture voltage frequency control system for a DRU-sent network construction energy storage new energy island. The island comprises a plurality of new energy stations, matched new energy storage stations and a DRU alternating current side energy storage station. Aiming at DRU side energy storage, on the basis of keeping active-frequency droop control, a reactive-voltage droop loop is replaced by a DC power-voltage control loop, and the DRU is controlled to send a power tracking scheduling instruction by adjusting an output voltage; for new energy side energy storage, active-frequency droop and reactive-voltage droop are adopted to construct a local voltage frequency, an active power compensation instruction distributed by a system-level constant-frequency control loop is received, a local active reference value is corrected, and system frequency indifference adjustment is realized. The method adapts to the specific power-voltage coupling characteristic of the DRU, the frequency can be kept stable when the new energy output fluctuates, the power is constantly sent out according to the scheduling instruction, and the operation reliability and schedulability of the island system are improved.

The application provides a half-controlled step frequency scanning variable scanning mode ultrasonic excitation signal generating device and method, and relates to the technical field of ultrasonic power supplies.The device structure comprises four parts of a power stage power conversion circuit, signal sampling and conditioning, a main controller and peripheral circuit, and a button and display circuit.The power stage power conversion circuit is composed of AC-DC conversion, power regulation, DC-AC inversion, impedance matching and series tuning modules.Through the program design of the main controller, different ultrasonic excitation signal frequency modes can be realized, including a constant frequency mode of keeping the center frequency, a constant scanning mode of constant step frequency scanning, and a variable scanning mode of half-controlled step frequency scanning.The variable scanning mode of half-controlled step frequency scanning provides a novel frequency excitation mode for ultrasonic auxiliary processing, is beneficial to the resonance of ultrasonic waves and complex material liquid, and helps to improve the acoustic-cavitation yield.

The application provides a power battery heating noise processing method and device and an electric vehicle, and relates to the field of noise control.The application comprises the following steps: receiving a power battery heating instruction, and generating a d-axis current instruction and a q-axis current instruction according to the power battery heating instruction; outputting a q-axis voltage through a PI controller according to the q-axis current instruction, so as to control the q-axis current with an output value of zero; controlling a d-axis voltage to be output through hysteresis control according to the d-axis current instruction; generating a random factor at a preset frequency, adjusting the amplitude of the d-axis voltage according to the random factor, randomly adjusting the current slope of the motor at each pulse current point, generating a random pulse current acting on the power battery, and making the noise generated in the battery heating process randomly distributed, so as to solve the problem that the existing power battery heating process using high-frequency constant-frequency alternating current generates high-frequency sharp and piercing noise.

The utility model provides a purified water double-softener single-machine operation mechanism which comprises a first tank body, a second tank body and a pretreatment water pump, adjustable electromagnetic valves are arranged on the outer sides of front and back washing water drainage pipelines of the first tank body and the second tank body, fixing mechanisms are arranged on the outer sides of the adjustable electromagnetic valves, and a water inlet and a water outlet are formed in the front and back washing water drainage pipelines of the first tank body and the second tank body. A protection mechanism is arranged on one side of the fixing mechanism, an auxiliary mechanism is arranged on the outer side of the protection mechanism, the pretreatment water pump communicates with the first tank body and the second tank body through a pipeline, and a pressure transmitter is arranged on the outer side of the pipeline. The single-machine operation mechanism for the purified water double softeners solves the problems that resin is easy to break due to overlarge flow during regeneration of the softeners, especially during forward and reverse washing of the softeners, and back pressure of the system is too low due to constant-frequency operation of a pre-treatment raw water pump, single-machine operation of the pre-treatment double softeners and regeneration forward and reverse washing of the other pre-treatment double softeners. And the system operation is influenced.

A transport system, a positioning device, a positioning method, a computer program product and a computer-readable recording medium. The positioning device comprises: a plurality of electronic tags arranged to be arranged at equal intervals along a line segment; and a fixed-frequency sampling module arranged to be able to move around the line segment. The fixed-frequency sampling module has two antenna parts and a positioning part. The positioning part is electrically connected to the two antenna parts. The two antenna parts couple the plurality of electronic tags and read the wireless radio frequency identification signals from the plurality of electronic tags at a fixed frequency. The positioning part estimates a coordinate on the line segment according to a plurality of identifiers and a plurality of intensity distribution curves from the wireless radio frequency identification signals. The antenna spacing between the two antenna parts is: d2=(n+0.5)×d1, d1 is a tag spacing between two adjacent electronic tags, n is an integer, and n≧0.

According to a first aspect of the present disclosure, there is provided a radar apparatus comprising: a plurality of receiver channels; a plurality of mixers, wherein each of the receiver channels comprises one of the mixers; a first frequency synthesizer configured to generate a chirp signal; at least one test tone generator configured to generate a test tone signal having a constant frequency; wherein the mixer is configured to be fed with the chirp signal and the test tone signal. According to a second aspect of the present disclosure, a corresponding method of operating a radar apparatus is conceived.

The invention relates to a controller for DC-DC converters and related systems and methods. A method for controlling a direct current-direct current (DC-DC) converter includes (a) operating the DC-DC converter in a constant frequency operating mode, (b) determining that a duty cycle of a first switching device of the DC-DC converter has exceeded a first threshold, and (c) controlling the DC-DC converter in response to the duty cycle of the first switching device of the DC-DC converter having exceeded the first threshold. The DC-DC converter is caused to reduce the switching frequency and operate the switch from the constant frequency operating mode to a constant off-time operating mode.

By extending the lifespan of the refrigeration unit and reducing the frequency of replacement, the operating rate of the MRI system will be improved. [Solution] The cold head life extension mode is implemented. In the cold head life extension mode, the refrigerator's displayer is operated at a constant frequency lower than a predetermined upper frequency, regardless of the temperature of the superconducting coil, and the compressor inverter controls the drive frequency of the compressor drive unit according to the temperature of the superconducting coil.

The invention belongs to the technical field of aviation power generation systems, and discloses an alternating current starting power generation system starting phase sequence online identification method, which comprises the following steps of: 1, providing 28V control electricity and 115V / 400Hz three-phase constant-frequency alternating current for a generator controller; 2, setting a current comparison threshold value, wherein a data acquisition period is as follows; the starting generator controller is used for converting the 115V / 400Hz three-phase constant-frequency alternating current into low-voltage three-phase constant-frequency alternating current; 3, applying the low-voltage three-phase constant-frequency alternating current to a three-phase winding of a main generator stator to generate three-phase current; step 4, collecting three-phase current fed back by a current sensor, and recording the three-phase current as,..., and collecting three-phase current fed back by a motor mutual inductor, and recording the three-phase current as,...; 5, calculating the sum of the three-phase current according to the sum; and 6, calculating the absolute value of the current sum in one current period, solving the average value of the absolute values of continuous N periods, if the average value is smaller than a set threshold value, indicating that the starting phase sequence is correct, otherwise, indicating that the starting phase sequence is wrong.

A plasma processing system includes a chamber configured to house plasma in a process space; a wafer holder configured to place a structure in the chamber, wherein the structure is configured to be etched by the plasma; a first chamber component arranged on a first side of the wafer holder and is applied with a first signal; and a second chamber component arranged on a second side of the wafer holder and is applied with a second signal, the second side opposite to the first side. The first signal is associated with a first constant frequency, and the second signal is associated with a second constant frequency.

The invention discloses a time interval error jitter extraction method based on Hilbert transform, and relates to the field of high-speed data signal processing. After obtaining the measured data signal, firstly, a level histogram is used for statistics, and a corresponding level judgment reference is determined; secondly, the measured data signal is subjected to Hilbert transform to obtain the time information of the transition edge of the measured data signal; a "coarse frequency estimation + fine frequency estimation" method is used to extract the accurate symbol rate of the measured data signal, and a high-precision constant frequency clock is recovered; and high-precision time interval error is extracted according to the above-mentioned recovered clock. The time interval error jitter extraction method based on Hilbert transform provided by the invention provides a basis for high-precision time interval error jitter, and accurately performs jitter measurement on the measured data signal.

This invention relates to a method and apparatus for resolving velocity ambiguity based on constant frequency assistance. The method includes the following steps: a radar sequentially transmits a constant frequency band signal and a linear continuously modulated pulse train, and acquires the radar echo signal; both the constant frequency band echo signal and the sawtooth band echo signal are mixed to obtain a constant frequency band intermediate frequency signal and a sawtooth band intermediate frequency signal; the constant frequency band intermediate frequency signal is processed by a fast Fourier transform to obtain a target true velocity estimate; the sawtooth band intermediate frequency signal is sequentially processed by a two-dimensional fast Fourier transform, a two-dimensional constant false alarm rate (CFAR) processing, and a centroid condensation processing to obtain a target range velocity estimate; based on a velocity matching method using a Fourier rotation factor, the target true velocity estimate is matched with the target range velocity estimate to obtain the true velocity of all targets. This method not only resolves velocity ambiguity but also improves velocity accuracy, offering advantages such as high velocity measurement accuracy, high real-time performance, and simplicity.

A method for controlling a direct current-to-direct current converter (DC-DC converter) comprises (a) causing the DC-DC converter to operate in a constant frequency mode, (b) determining that a duty cycle of a first switching device of the DC-DC converter has crossed a first threshold, and (c) causing the DC-DC converter to decrease the switching frequency and, in response to the duty cycle of the first switching device of the DC-DC converter crossing the first threshold, to switch from operating in constant frequency mode to operating in a constant off-time mode.

The application discloses a network topology of AC power reconstruction at a receiving end of DC power transmission and belongs to the technical field of power generation and power equipment. The network topology comprises a DC / AC converter connected with a DC power transmission line and used for converting DC power inputted by the DC power transmission line into AC power with adjustable frequency, size and phase; and a synchronous motor-synchronous generator set, wherein the AC power outputted by the DC / AC converter is connected to a stator side of the synchronous motor, drives the synchronous motor and a synchronous generator coaxially connected with the synchronous motor to rotate, the DC / AC converter drives the synchronous motor-synchronous generator set to start from static to variable frequency, and after the synchronous motor-synchronous generator set is started, the constant frequency output of the DC / AC converter drives the synchronous motor-synchronous generator set to rotate at a constant speed, and the synchronous generator outputs constant frequency AC power to be connected to an AC power grid at the receiving end. The application fundamentally solves the problem of AC power stability reconstruction at the receiving end of the DC power transmission.

The present invention relates to the field of power control technology, and specifically to a method for parallel operation of a box-type power supply multi-battery system, including: step S1, a host system reads the operation data and status information of each slave system; step S2, determines the currently available identification of each energy storage system; step S3, corrects the priority of each slave system; step S4, recalculates the priority number of the host system; step S5, reads the power instruction issued by the host system, and determines whether to convert the host system to a slave system. If not, each slave system outputs power according to the power instruction; otherwise, the slave system with the smallest priority number is converted to a constant voltage and constant frequency mode. The present invention can realize automatic adjustment of the master and slave systems when the host system is abnormal or discharged to the lower limit of the SOC, effectively improving the reliability of the multi-battery system when running in parallel.