1643 results about "Current amplitude" patented technology

Exemplary embodiments provide a system, method and appartus for regulating current in loads, such as in an array of independent pluralities of light emitting diodes (“LEDs”). An exemplary system comprises a multiplexer adapted to switch current to each independent string of LEDs; a first controller to maintain a substantially constant average current level to the plurality of LEDs; and a second controller to modulate a current amplitude and duration of time division multiplexing for each independent string of LEDs. Another aspect of the system provides for modulating the on time for switching current to maintain a substantially constant average current level and to respond and converge quickly to changing current reference levels.

Methods for determining the presence of double stranded nucleic acids in a sample are provided. In the subject methods, nucleic acids present in a fluid sample are translocated through a nanopore, e.g. by application of an electric field to the fluid sample. The current amplitude through the nanopore is monitored during the translocation process and changes in the amplitude are related to the passage of single- or double-stranded molecules through the nanopore. The subject methods find use in a variety of applications in which the detection of the presence of double-stranded nucleic acids in a sample is desired, e.g. in hybridization assays, such as Northern blot assays, Southern blot assays, array based hybridization assays, etc.

A solar electricity generating system includes a solar cell and a DC/AC converter coupled to the cell. The first proposed method includes the steps of: (a) adjusting an output current of the DC/AC converter; (b) sensing an output voltage variation of the solar cell; (c) adjusting the output current in a direction of the variation; and (d) repeating the steps (a) to (c). The second proposed method includes the steps of: (a) adjusting a DC output voltage of the solar cell; (b) sensing an output current amplitude variation of the DC/AC converter; (c) adjusting the output voltage in a direction of the variation; and (d) repeating the steps (a) to (c).

A disk drive is disclosed which demagnetizes the head after a write operation. Write circuitry applies a write signal to the head in order to write data to a selected data sector during a write operation, wherein the write signal comprises a predetermined write current amplitude. Control circuitry demagnetizes the head at the end of the write operation by maintaining the write current amplitude while increasing a frequency of an AC write signal applied to the head over a predetermined demagnetization interval, wherein increasing the frequency of the AC write signal decreases an amplitude of the AC write signal when observed at the head.

A method and apparatus for stimulating a muscle of a subject are provided. The apparatus comprises a signal generator for generating an electrical pulse signal of a frequency and a current amplitude for inducing contractions in the muscle, and an electrode apparatus for applying the signal to nerves associated with the muscle to be stimulated or adjacent the muscle of the subject for stimulating the muscle. The frequency and current amplitude of the electrical pulse signal are selected so as to maximize the bulk of the muscle being subjected to the contractions so as to generate a shivering phenomenon therein.

The invention discloses a parameter offline identification method for a permanent magnet synchronous motor under the condition of rest, belonging to the field of motor control and solving the problems of rotor external locking, overlong identification time, poor result consistency, poor practicability and the like of the existing parameter offline identification method for the permanent magnet synchronous motor under the condition of rest. The parameter offline identification method comprises the steps of: always keeping a rotor in a rest state, injecting a high-frequency voltage signal in a straight axis of a rotor winding, detecting a three-phase stator current and transforming into two-phase rotational coordinates, carrying out discrete Fourier transform on the current to obtain a straight axis high-frequency current amplitude so as to obtain a straight-axis inductance value through calculation; then injecting a high-frequency voltage signal in a quadrature axis of the stator winding, obtaining a quadrature axis inductance value by using the same method; and then introducing a linearly increasing current into the straight axis of the stator winding so as to obtain a voltage generating a corresponding current through reconstruction of a voltage of an inverter, calculating and fitting a straight slope by using a least square method by using a straight axis voltage value as a longitudinal coordinate and a straight axis current value as a transverse coordinate, and finally obtaining a slope value, wherein the slope value is a stator resistance value.

A resonant switching power converter having adaptive dead time control provides improved efficiency along with reduced EMI/audible noise and component stresses. A dead time between pulses generated by a switching circuit is adaptively set in conformity with a value of the input voltage to the resonant switching power converter and an indication of a magnitude of the current passing through inductive element of the resonant tank of the converter. The indication of the current magnitude may be the switching frequency of the converter, or a measure of line or load current levels. The dead time can be obtained from a look-up table or computed from the current magnitude and input voltage values.

The invention relates to the technical field of operation and control of an electric power system and discloses a method for detecting and identifying dynamic bad data of the electric power system. The method comprises the steps of A, reading a current network parameter and a network topology of the electric power system and forming a node admittance matrix and a branch circuit-node incidence matrix; B, establishing an equivalent circuit according to the network topology of the electric power system and configuring measurement functions and a power management unit (PMU) of the electric power system, wherein system measurement includes node voltage amplitude measurement, node current amplitude measurement, node power injection measurement and node trend measurement; C, detecting and identifying the dynamic bad data of the electric power system; D, judging the convergence condition. By means of the method, accidentally arisen bad data from a supervisory control and data acquisition (SCADA) system and in the PMU measurement can be found and eliminated, and accordingly an accurate operation state, voltage amplitude and phase angles of nodes of a power grid are obtained.

Methods and apparatuses for controlling a wearable neurostimulator from a control apparatus. Described herein are methods and apparatuses for controlling the application of ensemble waveforms using a transdermal electrical stimulation by a neurostimulator having a processor. The controller may provide specifically configured commands to efficiently and accurately control the delivery of an ensemble waveform by the neurostimulator, wherein the ensemble waveform includes a sequence of component biphasic current waveforms in which one or more parameters (such as frequency, current amplitude, percent duty cycle, and percent charge imbalance) vary between sequential component waveforms particularly effective at evoking a desired cognitive state by TES.

A driver for driving simultaneously a variable number of firing resistors for a printhead includes a drive circuit for supplying a drive signal for firing the variable number of firing resistors, and a circuit for adjusting a voltage or current magnitude of the drive signal in dependence on the variable number of firing resistors to be fired simultaneously.

The invention relates to an electric secondary AC circuit detection method which comprises the following steps: before a power plant machine set is started, a low-voltage short-circuit point or a short-circuit bogie is input; three-phase 380 V voltage is added at the high-voltage side of a booster station to form a circuit by means of the impedance of a transformer and a generator; current amplitude and phase are measured through a current detecting apparatus to check polarity and transformation ratio in advance; all current protective directions such as generator differential motion are measured. When a neutral point is not connected, a short-circuit point is made at a high plant transformer low-voltage side, and the three-phase 380 V voltage is added at the neutral point of the generator, thereby realizing overall checkup of a generator AC circuit; then, the three-phase 380 V voltage is converted into one-phase voltage or two-phase voltage to carry out overall checkup of a zero sequence circuit. The detection method can check all CT and PT circuits of a generation-transformer group before power transmission; moreover, all protection directions of the generation-transformer group are checked in advance, thereby saving time and fuel oil along with economical efficiency, environmental protection and safety. The electric secondary AC circuit detection method can check secondary circuits such as the transformer and the bus differential protection of a transformer substation.

The sectional detection method of small current earthing fault of power system, especially single phase long distance system, is suitable for system with several detection units in different sectionsof the line. Each unit variance in zero-sequence voltage or current is used as fault starting condition, the transient zero-sequence current amplitude and initial polarity are calculated, and the main station determines the fault section based on the fault information the detectors report. The basic criterion is that the transient zero-sequence currents on two sides of the fault point have opposite polarity and that each transient zero-sequence current amplitude is proportional inversely to the distance to the fault point. The said method is suitable for system with unearthed neutral point, earthed arc extinguishing coil or high earthing resistance as well as system with reactive load.

An apparatus and system are disclosed for protecting a power distribution unit from an electrical fault. A fuse interrupts a flow of electrical current in response to the electrical current rising above a current rating of the fuse. A current sensor measures the amplitude of the electrical current and outputs a current amplitude signal. A relay interrupts the flow of electrical current in response to an OFF signal. A fault module receives the current amplitude signal and sends the OFF signal to the relay in response to the amplitude of the electrical current exceeding a threshold value. The relay, the fuse, and the threshold value are selected so that a switching time of the relay is less than an opening time of the fuse for an amplitude of the electrical current between the threshold value and a maximum fault current value, so that the relay prevents the fuse from opening.

The present disclosure involves a method of setting stimulation parameters for neurostimulation. A plurality of stimulation parameters available for bracketing is displayed. The stimulation parameters are selected from the group consisting of: stimulation current amplitude, pulse width, frequency, and contact location. Thereafter, in response to an input from a user, at least a subset of the stimulation parameters is selected for bracketing. A respective initial value is then obtained for each of the stimulation parameters in the selected subset. Thereafter, a bracketing process is used to generate a plurality of bracketed values for each of the stimulation parameters in the selected subset. The bracketed values are generated as a function of the initial value. A plurality of stimulation pulses is then delivered to a patient through a neurostimulator that is automatically programmed with a different combination of the bracketed values for the stimulation parameters for each stimulation pulse.

Methods and apparatuses for amplitude modulation of all or a portion of an ensemble waveform to modify a user's cognitive state by transdermal electrical stimulation (TES). An ensemble current waveform may include a sequence of component biphasic current waveforms in which one or more parameters (such as frequency, current amplitude, percent duty cycle, and percent charge imbalance) vary between sequential component waveforms. These ensemble waveforms may be specifically configured to evoke a particular cognitive state when applied by TES. In particular, described herein are methods for applying amplitude modulation to all or a sub-set of the component waveforms in the ensemble waveform which may dramatically enhance the efficiency and effectiveness of the TES. Also described herein are methods and apparatuses for applying amplitude modulation to all or a portion of an ensemble waveform without truncating pulses of the component waveforms forming the ensemble waveform.

The invention discloses a scheme for controlling the grade parking of a permanent magnet motor-driven pure electric vehicle. The pure electric vehicle has an electrical system comprising a battery pack, a motor, a power converter, a motor controller and a vehicle controller and further comprising corresponding voltage, current and tilt sensors. The scheme comprises two steps of: (1) detection for the initial position of a rotor of a permanent magnet synchronous motor: a detection voltage is applied to the permanent magnet synchronous motor by the power converter, and the initial spatial position of the motor rotor in the case that the vehicle is stationary is calculated through a current feedback signal; and (2) torque self-balancing strategy based on vector control: the torque self-balancing characteristic can enable driving torque to track load torque automatically. The torque required by parking is calculated in accordance with the tilt angle of a ramp on which the vehicle is to be parked, and then, reasonable current amplitude and phase are given according to the initial position of the rotor and the torque required by grade parking in order to enable the driving torque to be equal to the load torque, therefore, stationary parking of the vehicle on the grade is realized.

The invention provides a method for determining insulation and lightning impulse withstanding properties of a same-tower double-loop power transmission line. The method comprises the following steps: determining the same-tower double-loop power transmission line to be determined, acquiring statistical parameters of lightning activities in an area in which the power transmission line is located and structural parameters of each pole tower and determining a lightning strike calculation cycle number Nl; sampling random parameters during a lightning strike process and determining lightning current amplitude, transient power frequency voltage and determination result that the lightning strike is shielding failure or back striking; judging whether tripping occurs in the pole tower after the certain lightning strike or not and carrying out statistics on the tripping times during the Nl lightning strikes according to the lightning current amplitude, the transient power frequency voltage and the shielding failure or back striking determination result, as well as the structural parameters of the pole tower, and calculating the lightning strike tripping rate; and determining the insulation and the lightning impulse withstanding properties of the power transmission line according to the lightning strike tripping rate and a target value. The determination method provided by the invention is small in error, high in precision and specific; and by adopting the determination method, design, operation and improvement of lightning protection measures of the same-tower double-loop power transmission line of an electric power department can be scientifically guided.

The invention relates to the technical field of electric power system operation and control and discloses an electric power system dynamic state estimation method based on a synchronous phase-angle measuring device. According to the technical scheme, the method comprises the steps of A, reading current network parameters of an electric power system and a network topological structure of the electric power system, and therefore forming a node admittance matrix and a branch-node incidence matrix; B, establishing an equivalent circuit according to the network topological structure of the electric power system, and configuring a measurement function of the electric power system and a PMU of the electric power system, wherein the measurement of the system comprises node voltage amplitude measurement, node current amplitude measurement, node power injection measurement and node load flow measurement; C, conducting dynamic state estimation on the system on the basis of extended Kalman filtering; D, judging conditions of convergence. According to the electric power system dynamic state estimation method based on the synchronous phase-angle measuring device, due to the introduction of the PMU, real-time and accurate measurement information such as the voltage and the phase angel can be supplied to the system, the higher measurement redundancy rate of the system is obtained, and therefore the precision of the state estimation is improved. The electric power system dynamic state estimation method based on the synchronous phase-angle measuring device has the advantages of being good in robustness, high in state estimation precision and good in convergence performance.

The invention belongs to the technical field of automation engineering and discloses a method for controlling the direction of a rotation axis and the rotation direction of a space universal superposition rotating magnetic field. Three z-axis, y-axis and x-axis square Helmholtz coil groups are orthogonally nested, so that when the three groups of coils are driven by direct currents with the same current strength, the magnetic inductions generated at the center points of the three groups of coils have the same strength; the superposition rotating magnetic field is driven by an amplitude and phase compensation voltage signal through digitization so as to eliminate the influence of current lagging and inductive reactance on the current amplitude; and a same-frequency three-phase sinusoidal signal with the amplitude and the phase related to the axis azimuthal angle of a robot is used for driving to form the space universal uniform rotating magnetic field with the corresponding azimuthal rotating axis in a superimposed mode in a certain space surrounded by the three-axis orthogonal Helmholtz coil devices. According to the invention, by implementing the random regulation of the direction of the rotation axis and the rotation direction of the space universal rotating magnetic field, various operations of turning, moving forward, moving backward and the like of the micro robot in the bent or branch cavity environment are further implemented; and the method has wide application prospect.