1225 results about "Constant frequency" patented technology

Systems, methods, and apparatus for providing power to an electrosurgical instrument. In particular, a power supply is disclosed in which non-sinusoidal (e.g., pulsed) constant frequency voltage having a variable amplitude is passed to an LC circuit to produce a quasi-sinusoidal current in the LC circuit. The constant driving frequency can be one half the resonant frequency of the LC circuit allowing the LC circuit to operate as an impedance, and thus limit current spikes and arcing. The frequency and phasing of the driving voltage also enables the LC circuit to discharge energy back into a power provider of the power supply so that energy does not build up in the LC circuit. These features result in less severe current spikes and arcing, as well as reduced cutoff times.

A cashless business transaction system (e.g., a vending system, a material tracking system, or a highway toll system) incorporates a method and apparatus for transmitting a digital information signal. A signal generator (311) generates a constant frequency signal. A phase modulator (305) varies the instantaneous phase of the constant frequency signal to represent digital information, thereby producing a phase modulated signal (325). A tuned resonant circuit (307) filters and averages the phase modulated signal to produce a simulated FM signal, and transmits the simulated FM signal via its antenna (309). One such business transaction system (e.g., a vending system) incorporates such a transmitter to facilitate transmission of billing information from a device located within a substantially electrically shielded environment. Another such business transaction system preferably incorporates such a transmitter to facilitate half-duplex transmission of digital information regardless of whether or not the digital information is transmitted from a device located within a substantially electrically shielded environment.

A variable speed wind turbine is disclosed comprising a turbine rotor that drives a doubly-fed induction generator, a matrix converter which converts variable frequency output into constant frequency output, and a control unit and a protection circuit for the matrix converter. Power is circulated in the system allowing for sensorless detection of rotor position and better output ratios of power from the system.

A variable speed wind turbine is disclosed comprising a turbine rotor that drives a doubly-fed induction generator, a matrix converter which converts variable frequency output into constant frequency output, and a control unit and a protection circuit for the matrix converter. Power is circulated in the system allowing for sensorless detection of rotor position and better output ratios of power from the system.

The present invention is related to an electrochemical biosensing test strip, biosensing meter, system and method for analyte measurement incorporating a hematocrit correction. The biosensor strip comprises a first and a second electrode sets respectively for detecting analyte concentration and hematocrit level. The first and second electrode sets are respectively corresponding to different reaction zones and a reaction reagent is only formed on the first electrode set corresponding reaction zone. Applying a first signal comprising a DC component and a second signal comprising an AC component that has a constant frequency respectively to the first and second electrode sets can respectively detect an uncorrected analyte concentration and hematocrit level. Therefore, the corrected analyte concentration is more accurate by incorporating the hematocrit correction.

An apparatus for reducing vertical segregation of a discharge lamp. A current / voltage input sweeps through a frequency range between the first azimuthal acoustic resonance mode and a first radial acoustic resonance mode of the discharge lamp. The current / voltage input is subsequently amplitude modulated. Alternatively, without amplitude modulation, the current / voltage input sweeps through the frequency range for a first portion of the period, and then for a second portion of the period drops to a relatively constant frequency.

A starter-generator for an aircraft engine comprises a dynamoelectric machine alternatively operable as a motor or as a generator, having a rotor. A support motor is coupled to the dynamoelectric machine to assist the machine. A torque converter selectively couples and decouples the rotor to the engine, coupling the rotor to the engine at some point when dynamoelectric machine is operated as a motor. A constant speed transmission has an input adapted to be connected to the engine and an output to be connected to the rotor. The unit provides a desired speed relation between input and output. The engine may be started by the dynamoelectric machine when operated as a motor through a first power train including the torque converter and may drive the dynamoelectric machine as a generator through a second power train including the constant speed transmission.

The invention provides an unmanned aerial vehicle bridge bottom surface crack detection method and system. The unmanned aerial vehicle bridge bottom surface crack detection system comprises an unmanned aerial vehicle end and a ground workstation. The unmanned aerial vehicle end utilizes an airborne laser radar and an inertial measurement unit to position an unmanned aerial vehicle and form an unmanned aerial vehicle peripheral barrier point cloud to avoid barriers and plan a path; and an airborne platform camera photographs a bridge bottom surface at a constant frequency and stores a high-definition image into a memory. The ground workstation processes the photographed image, and splices an image between bridge piers to form a large-sized bridge bottom surface image; then the edge information in the image is acquired, the morphological corrosive expansion and connection are performed on the edge to extract a complete crack, and the crack is roughly positioned by virtue of a bridge pier position at which the spliced image is arranged; and finally the crack is evaluated, and information about the crack such as a length, a width, a distribution density and the like is analyzed and measured. The unmanned aerial vehicle bridge bottom surface crack detection method and system are high in automation degree, high in efficiency, high in safety coefficient, low in cost and wide in application prospect on the aspect of the bridge bottom surface route inspection.

The invention relates to a control method which can be applied to an active-clamp flyback miniature photovoltaic grid-connected inverter device. The active-clamp flyback miniature photovoltaic grid-connected inverter device comprises a flyback converter and a power frequency polarity conversion circuit. In the device, a current reference is used for controlling a flyback primary-side current peak value so that the device can output a half-wave sinusoidal current, and the output voltage is clamped by a grid voltage. When the instantaneous power is lower, a constant frequency current discontinuous mode in combined with a variable frequency current critical continuous mode is adopted in the flyback control method. When the flyback converter works in a variable frequency current critical discontinuous mode, an auxiliary switching tube can be conducted for a period of time when the secondary-side current of the flyback converter reaches zero, the conduction time can be accurately controlled by a digital chip, thus realizing the leakage inductance energy feedback and the soft switch of a master switching tube under the condition of wide-range output voltages and different instantaneous powers and greatly improving the efficiency under the condition of full loads.

The present invention relates to variable speed constant frequency (VSCF) devices and methods for maximizing engine generator efficiency. In one embodiment, a VSCF device may include at least two paths for conducting power to the load. One path, a line inductor path, may advantageously incur minimal power loss when the engine generator is supplying rated power to a load. A second path, a VSCF path, may be used to ensure that the frequency of the power is maintained at a substantially constant frequency under various load conditions. Another embodiment of the invention describes a process for determining optimal engine generator speed for a particular load. Because engine speed can be varied using any VSCF device, this process determines a speed that minimizes fuel consumption, emissions, and noise pollution for a given load.

A distributed fiber optic sensor simultaneously interrogates the sensing fiber with two counter propagating light beams. One beam is set to a constant frequency. The second beam is modified to contain a “comb” of frequencies, with each frequency component in the comb offset by a predetermined amount. Each of the frequency components in the comb, herein referred to as teeth, is able to interact with the counter-propagating beam through the Brillouin scattering process. With proper selection of the comb characteristics such as the number of teeth, the frequency spacing of teeth, the spectral width of teeth, and the relative amplitude of the teeth, a representation of the Brillouin spectrum at each point in the fiber can be obtained simultaneously with a single pass through the fiber.

A method for frequency modulated continuous wave LADAR imaging is provided. The method comprises the steps of generating a chirped laser signal and a constant-frequency laser signal, forming a target laser signal from the chirped laser signal and the constant-frequency laser signal and forming a local oscillator laser signal from the chirped laser signal and the constant-frequency laser signal. The method further comprises delaying or frequency shifting the local oscillator laser signal and directing the target laser signal to a target. The method further comprises combining a returned signal received from the target with the delayed or frequency shifted local oscillator laser signal to form a combined received signal, and capturing the combined received signal with a plurality of image sensors. The method further comprises performing a nonlinear operation on the captured combined received signal and Fourier transforming the captured combined received signal to determine a range corresponding to each of the plurality of image sensors in the imaging device.

A method and apparatus are disclosed for determining the concentration of individual components within a fluid mixture by determining the permittivity of the individual components. The method and apparatus use a reference sensor and at least one measurement sensor positioned inside the same sensor device that is immersed in the fluid mixture to be measured. Signals, such as radio frequency or microwave, are sequentially transmitted at multiple, known, constant frequencies to and reflected from both the reference and measurement sensor(s). Permittivities of the individual components are determined from these transmitted and reflected signals and information about the concentration of the individual fluids and other compounds within the fluid mixture and the density of the fluid mixture are produced. Repetitive sampling and processing of these signals allow determination and real-time monitoring of the concentration of individual components within a mixture of fluids. The present invention provides self-calibration, accurate frequency maintenance and self-selection of an operating frequency range.

The invention discloses a dynamic power coordination control method for a battery energy storage system. The battery energy storage system comprises a plurality of power converters which supply power to a load and are connected in parallel for operation, and is characterized in that: the power converters connected in parallel for operation are divided into two types, and a master-slave control scheme is adopted, wherein one type comprises only one power converter which adopts a constant voltage constant frequency control mode and is called a master node, and the power converters of the other type adopt a constant power mode with a slight droop characteristic, and serve as slave nodes; generally, a power converter with a high capacity is selected to be the only one master node which is specified by an upper-layer monitoring system, and all the other power converters are the slave nodes; and under a stable state condition, active power and reactive power output by the power converters which serve as the slave nodes are set by a power instruction transmitted by the monitoring system, and the output power of the power converter which serves as the master node is dynamically regulated according to a load condition. The method adopting the master-slave control scheme has the advantages that: on the premise of sufficient power capacity, both the voltage stability and frequency stability of a micro-grid system are easily achieved, anti-load disturbance capability is high, and failure recovery time is short.

Mechanism for displaying the day and phase of at least a first celestial body, comprising a gear train for a constant frequency gear drive on an output of a timepiece movement. This mechanism includes a means for the three-dimensional display of the day and phase of said first celestial body represented by a first mobile component, which is driven by the gear train, which includes a phase train and a day train, each in mesh on an output of this same movement.This phase train and / or this day train include at least one uncoupling means between the input and its output thereof.

A ground-penetrating radar comprises a software-definable transmitter for launching pairs of widely separated and coherent continuous waves. Each pair is separated by a constant or variable different amount double-sideband suppressed carrier modulation such as 10 MHz, 20 MHz, and 30 MHz Processing suppresses the larger first interface reflection and emphasizes the smaller second, third, etc. reflections. Processing determines the electrical parameter of the natural medium adjacent to the antenna.The modulation process may be the variable or constant frequency difference between pairs of frequencies. If a variable frequency is used in modulation, pairs of tunable resonant microstrip patch antennas (resonant microstrip patch antenna) can be used in the antenna design. If a constant frequency difference is used in the software-defined transceiver, a wide-bandwidth antenna design is used featuring a swept or stepped-frequency continuous-wave (SFCW) radar design.The received modulation signal has a phase range that starts at 0-degrees at the transmitter antenna, which is near the first interface surface. After coherent demodulation, the first reflection is suppressed. The pair of antennas may increase suppression. Then the modulation signal phase is changed by 90-degrees and the first interface signal is measured to determine the in situ electrical parameters of the natural medium.Deep reflections at 90-degrees and 270-degrees create maximum reflection and will be illuminated with modulation signal peaks. Quadrature detection, mixing, and down-conversion result in 0-degree and 180-degree reflections effectively dropping out in demodulation.

The present invention relates to a circuit layout of a switch type regulator and control method thereof. The switch type regulator according to one embodiment of the invention includes: (1) a filter network connected to the output terminal, wherein the output voltage of the output terminal is generated by an input source; (2) an active switch connecting the input source to a wave filter circuit, wherein the active switch is periodically connected and disconnected, and the conducting duty cycle of the switch period is modulated by a PWM control signal; (3) a comparator, which receives output feedback signals, a delay signal and a reference delay, and provides the PWM control signal; (4) a delay programming circuit for generating the delay signal and a ramp control signal, wherein the delay signal is set up based on the status of the input source and the output voltage, to obtain an operating status with fundamentally constant frequency.

The embodiment of the invention provides a control method and device for an air-conditioner draught fan. The control method and device for the air-conditioner draught fan can make the output capability of an air-conditioner and the indoor load be consistent. The control method comprises the steps that the indoor temperature is detected according to a preset first detection period; at the current detection moment, the temperature difference value of the indoor temperature and a setting temperature and the change rate of the indoor temperature are obtained, or the temperature difference value of the indoor temperature and the setting temperature and the variable quantity of the indoor temperature in one detection period are acquired; according to the temperature difference value and the change rate of the indoor temperature, or on the basis of the temperature difference value and the variable quantity of the indoor temperature in one detection period, the indoor draught fan of the constant-frequency air-conditioner is controlled to operate according to preset rules; the preset rules comprise that when the temperature difference value is within a preset threshold range, under the condition of a certain temperature difference value, the air speed of the indoor draught fan is decreased as the change rate of the indoor temperature / the variable quantity of the indoor temperature in one detection period is increased gradually. The control method and device for the air-conditioner draught fan are suitable for the field of air-conditioners.

In electric power supply through wireless signals, electric power is supplied efficiently, even when distance fluctuation is caused between an electric power transmitting device and an electric power receiving device. Even when distance fluctuation is caused between the electric power transmitting device for supplying electric power with the use of wireless signals and the electric power receiving device for receiving electric power supplied from the electric power transmitting device, the Q value of the electric power transmitting device is adjusted to optimize the transmission efficiency. The impedance of a resonance circuit of the electric power transmitting device is fluctuated at a constant frequency, the resulting reflected wave is detected as a response signal by the electric power transmitting device, and the Q value of the electric power transmitting device is adjusted to optimize the transmission efficiency.

The present invention includes a turn-off signal modulating circuit that periodically varies a turn-off timing of a switching element 2 at a preset modulation time after a current detection by a drain current detecting circuit 15, and by modulating the peak of a current flowing through the switching element 2, diffuses switching noise while preventing concentration of an oscillating frequency at a constant frequency even under a constant input voltage and a constant load.

A switched regulator circuit provides step-up and step-down operation in which the level of the input voltage can be greater, equal to, or less than a preset controlled output voltage. A four switch arrangement or two switch arrangement provides buck, boost, and buck-boost regulation under constant frequency valley-peak current mode control. A single sense resistor may be utilized for sensing inductor current during only a short period during each duty cycle. As an alternative to the sense resistor, the switches themselves can be used to sense current during operation.

A method and apparatus are disclosed for determining the concentration of individual components within a fluid mixture by determining the permittivity of the individual components. The method and apparatus use a reference sensor and at least one measurement sensor positioned inside the same sensor device that is immersed in the fluid mixture to be measured. Signals, such as radio frequency or microwave, are sequentially transmitted at multiple, known, constant frequencies to and reflected from both the reference and measurement sensor(s). Permittivities of the individual components are determined from these transmitted and reflected signals and information about the concentration of the individual fluids and other compounds within the fluid mixture and the density of the fluid mixture are produced. Repetitive sampling and processing of these signals allow determination and real-time monitoring of the concentration of individual components within a mixture of fluids. The present invention provides self-calibration, accurate frequency maintenance and self-selection of an operating frequency range.

An autozeroed comparator controls a frequency fsw of the input voltage inputted to a DC / DC converter. A digital frequency synchronization circuit is connected to the autozeroed comparator so as to form a phase locked loop, wherein the DES circuit controls the hysteretic window of the autozeroed comparator so as to lock fsw to a clock reference frequency. A plurality of slave phase circuits may be connected to the master phase circuit including the DFS circuit and the autozeroed comparator. Duty cycle calibration circuits adjust a duty cycle signal applied to each of the slave phase circuits, in response to average current measured in the slave phase circuits, so that each slave phase circuit is synchronized with the master phase circuit. A 6 A 90.5% peak efficiency 4-phase hysteretic quasi-current-mode buck converter is provided with constant frequency and maximum ±1.5% current mismatch between the slave phases and the master phase.

A dual-wire MAG welding control method features that the welding current feedback and voltage feedback are compared with the given signals in time shared mode, a control circuit is used to control welding, and during the welding two welders with constant frequency are used by keeping certain phase relation for high stability. Its welding power supply features that its controller uses a switching circuit consisting of current sampler, voltage sampler, switching switch, comparator, integral proportioner and amplifier connected to welding power output unit.

The present invention includes a turn-off signal modulating circuit that periodically varies a turn-off timing of a switching element 2 at a preset modulation time after a current detection by a drain current detecting circuit 15, and by modulating the peak of a current flowing through the switching element 2, diffuses switching noise while preventing concentration of an oscillating frequency at a constant frequency even under a constant input voltage and a constant load.

This invention relates to variable speed and constant frequency wind force generating system by use of double feedback sensing motor and its parallel interconnected control method, which comprises double sense motor, exciting transducer, DSP unit, electricity collecting unit, speed, position sense unit and drive unit. The method comprises the following steps: controlling exciting transducer and using it to control double feedback motor rotors to generate voltage; controlling the motor rotor voltage phase, frame and frequency without single simultaneous control on net voltage and rotor voltage; in motor speed range of 0 to 0.5s, the drive unit starting drive exciting transducer with wide rotation speed range and low demands; the control process adopting current open control.

A method and a device for measuring a physiological variable in a living body, whereby a transmitter (1) is disposed outside of the body to transmit radio frequent energy, and a receiver (3) of radio frequent energy is disposed outside of the body. A transponder unit (2), having a sensor (11) sensitive to the physical variable, and a modulator unit (12) for controlling the radio frequent energy absorption of the transponder unit according to a time-sequence representing said physical variable, is introduced into the body. The transmitter sends radio frequent energy of substantially constant frequency and amplitude onto the transponder, and the receiver monitors the radio energy absorption of the transponder unit to determine the time-sequence representing said physical variable. The time-sequence is decoded to interpret it as a measure of the physical variable.