3389 results about "Excitation current" patented technology

Apparatus and methods are provided for monitoring cardiac output using bioelectrical impedance techniques in which first and second electrodes are placed in the trachea and / or bronchus in the vicinity of the ascending aorta, while an excitation current is injected into the thorax via first and second current electrodes, so that bioelectrical impedance measurements based on the voltage drop sensed by the first and second electrodes reflect voltage changes induced primarily by blood flow dynamics, rather than respiratory or non-cardiac related physiological effects. Additional sense electrodes may be provided, either internally, or externally, for which bioelectrical impedance values may be obtained. Methods are provided for computing cardiac output from bioelectrical impedance values. Apparatus and methods are also provided so that the measured cardiac output may be used to control administration of intravenous fluids to an organism or to optimize a heart rate controlled by a pacemaker.

A photovoltaic system includes a plurality of photovoltaic modules and a DC motor connected to a three-phase generator driven by a shaft. The three-phase generator is connected to a power mains. The electric power supplied to the DC motor by the plurality of photovoltaic modules is repeatedly measured and adjusted, by changing an external excitation current of the DC motor, to the peak power attainable at the current ambient temperature and the current incident solar radiation intensity. The peak power is preferably determined by incrementally changing the excitation current in predetermined time intervals, until the supplied electric power produces a power level which can be regarded as the peak power.

An antenna described herein includes a driven patch that is configured to emit radiation in a broadside direction in response to receiving excitation current, wherein the driven patch has a first radiating edge and a second radiating edge that are approximately parallel to one another. The antenna also includes a reflector element that is configured to reflect radiation emitted from the first radiating edge in a quasi-endfire direction. The antenna can also include two director elements that are configured to direct radiation emitted from the second radiating edge of the driven patch in a quasi-endfire direction.

A power supply for applying a voltage to a scanning electromagnet for deflecting a charged particle beam has a first power supply unit having no filter and a second power supply unit having a filter. When an irradiation position of the charged particle beam in an irradiation object is moved, the first power supply unit, namely a power supply unit having no filter, is used to apply the voltage to the scanning electromagnet, so that an exciting current flowing in the scanning electromagnet can be changed in a short time. Further, when the irradiation position of the charged particle beam is maintained, the second power supply is used to apply a voltage whose pulsating component was removed to the scanning electromagnet, so that the exciting current flowing in the scanning electromagnet can be controlled precisely. Consequently, the charged particle beam can be applied uniformly to the irradiation object and an irradiation time of the charged particle beam to the irradiation object can be curtailed.

Provided is a thin-film magnetic head that can stably generate electromagnetic field with a desired frequency, even under the existence of significantly strong write field with frequently reversed direction. The head comprises an electromagnetic-field generating element between the first and second magnetic poles. The electromagnetic-field generating element comprises a spin-wave excitation layer provided adjacent to the first magnetic pole and having a magnetization with its direction varied according to external magnetic fields, for generating an high frequency electromagnetic field by an excitation of spin wave. And a magnetization of the spin-wave excitation layer is biased in a direction substantially perpendicular to its layer surface by a portion of magnetic field generated from the first magnetic pole, and pin-wave excitation current flows in the electromagnetic-field generating element in a direction from the second pole to the first pole.

The viscometer provides a viscosity value (Xη) which represents the viscosity of a fluid flowing in a pipe connected thereto. It comprises a vibratory transducer with at least one flow tube for conducting the fluid, which communicates with the pipe. Driven by an excitation assembly, the flow tube is vibrated so that friction forces are produced in the fluid. The viscometer further includes meter electronics which feed an excitation current (iexc) into the excitation assembly. By means of the meter electronics, a first internal intermediate value (X1) is formed, which corresponds with the excitation current (iexc) and thus represents the friction forces acting in the fluid. According to the invention, a second internal intermediate value (X2), representing inhomogeneities in the fluid, is generated in the meter electronics, which then determine the viscosity value (Xη) using the two intermediate values (X1, X2). The first internal intermediate value (X1) is preferably normalized by means of an amplitude control signal (yAM) for the excitation current (iexc), the amplitude control signal corresponding with the vibrations of the flow tube. As a result, the viscosity value (Xη) provided by the viscometer is highly accurate and robust, particularly independently of the position of installation of the flow tube.

A method and apparatus control a power converter (20) of an AC motor drive system (10). The method and apparatus: generate a field current regulating signal to control a field current component flowing from the power converter (20) to the AC motor (30), thereby achieving field current regulation; generate a torque current regulating signal to control a torque current component flowing from the power converter (20) to the AC motor (30), thereby achieving torque current regulation, the torque current regulation having lower priority than the field current regulation; and execute a close-loop field weakening control scheme, which generates a field weakening control command as a function of the difference between a torque current regulation voltage demand and voltage available for torque current regulation. The field current regulating signal is adjusted in accordance with the field weakening control signal to selectively reduce back EMF of the AC motor (30), thereby enabling the step of generating a toque current regulating signal to achieve a toque current component needed to drive the AC motor (30) at a desired speed despite a limitation on DC voltage available to the power converter (20).

A switched current temperature sensing circuit (1) comprises a measuring transistor (Q1) which is located remotely of a measuring circuit (5) which applies three excitation currents (I1,I2,I3) of different values to the measuring transistor (Q1) in a predetermined current sequence along lines (10,11). Resulting base / emitter voltages from the measuring transistor (Q1) are applied to the measuring circuit (5) along the same two lines (10,11) as the excitation currents are applied to the measuring transistor (Q1). Voltage differences ΔVbe of successive base / emitter voltages resulting from the excitation currents are integrated in an integrating circuit (36) of the measuring circuit (5) to provide an output voltage indicative of the temperature of the measuring transistor (Q1). By virtue of the fact that the measuring transistor (Q1) is excited by excitation currents of three different values, the effect of current path series resistance in the lines (10,11) on the output voltage indicative of temperature is eliminated. The predetermined current sequence in which the excitation currents are applied to the measuring transistor (Q1) is selected to minimize the voltages in the integrating circuit (36) during integration of the voltage differences ΔVbe.

This invention relates to one gas wheel motor rotor coil shortcut online test method in the test technique field, which comprises the following steps: through online real time collecting motor electrical parameter data and according to one certain work situation motor electrical parameter data to compute normal current theory values by reverse rotor normal current; then computing excitation magnetic current real value and theory value relative bias; the bias difference is as generation motor set to judge whether there is coil short cut fault as dialogue of the shortcut fault.

The invention involving a magnetorheological fluid damping device for automobile suspension system.The magnetic field generator of this damping device consists of permanent magnet and electromagnetic coil.On the top of the damping device,there are guide apparatus and damping regulator,the function of which is that to ensure the damping channel is uniform annular duct and to meet the high-damp requirement in the restoration process and low-damp requirement in the compression process of damper seperately.The current in the electromagnetic coil designs of bi-directional and this controls the magnetic field intersity of the damping channel,decreases the excitation current of the electromagnetic coil,reduces energy consumption and decreases damper fever.On the non-controlling conditions,this damping device has the equivalent characteristics of the traditional shock absorber and can instead the passive shock absorber,after equiping corresponding current controller,this device can regulate the damping characteristics of suspension system,which improves the automobile driving safety and ride comfort.

The invention provides an alternating-current brushless generator fault detection method based on an exciter exciting current. The method comprises the following steps: firstly, measuring the direct-current component and each subharmonic amplitude value of the exciter exciting current of a generator set; and then, detecting whether the generator set generates electrical failures or not with a stator winding turn-to-turn short circuit diagnosis algorithm, a rotor winding turn-to-turn short circuit diagnosis algorithm, an exciter fault diagnosis algorithm and a rotary rectifier fault diagnosis algorithm, wherein the electrical failures comprise stator winding turn-to-turn short circuit, rotor winding turn-to-turn short circuit, exciter rotor winding turn-to-turn short circuit, exciter rotor winding interphase short circuit, open circuit of one diode of the rotary rectifier and short circuit of one diode of the rotary rectifier. According to the LabView development fault diagnosis algorithm, various electrical faults can be detected by measuring the exciter exciting current so as to save measurement points, and various invasive sensors do not need to be installed in the generator. The alternating-current brushless generator fault detection method has good instantaneity, and the on-line detection requirement can be satisfied.

A DC-DC converter of synchronous rectification type is provided which comprises: a current detector (51) for discerning electric current (IQ1, IQ2) flowing through a primary side circuit; first and second DC biasing power supplies (53, 54) for producing a bias voltage (VBS1, VBS2) higher than voltage corresponding to excitation current through transformer (4); and first and second comparators (55, 57) for activating first and second rectifying MOS-FET (7, 8) when current detector (51) produces the detection voltage (VDT) over bias voltage (VBS1, VBS2) of first and second DC biasing power supplies (53, 54). As each of first and second rectifying MOS-FETs (7, 8) in secondary side circuit is driven synchronously with electric current (IQ1, IQ2) flowing through the primary side circuit except excitation current component through transformer (4), the converter can minimize switching loss in each rectifying MOS-FET (7, 8) in secondary side circuit to improve conversion efficiency.

Disclosed is a solenoid type electromagnetic operating device which needs a relatively large current only for a limited short period at an excitation start initial stage and is adapted to achieve the speeding up at an excitation start stage and an improvement in responsiveness as well as power saving without increasing a power load on each of a drive circuit and power supply. The device is used for exerting a mechanical output on a valve element against a spring force, and comprises a solenoid coil composed of a plurality of split coils mutually electrically independent, an iron core structure including a fixed core, a movable core and a yoke and assembled with the solenoid coil so as to form a magnetic path loop through which magnetic fluxes from the split coils pass in common, an excitation controller for selectively switching / controlling the excitation current to each split coil, and a transmission mechanism for transmitting the mechanical output based on the displacement of the movable core magnetically attracted to the fixed core to the valve element when one or more of the split coils are excited.

A vehicle motor-generator apparatus based on a field winding type of synchronous machine coupled to a power inverter and a battery, wherein the synchronous machine is controlled to operate as a motor to perform engine starting and thereafter be driven by the engine as an electrical generator, wherein during a short time interval at the commencement of engine starting, the armature winding of the synchronous machine is driven by a current such that magnetic flux is produced by the armature winding acting in the same direction as magnetic flux produced by the field winding, to thereby achieve increased torque during the time when maximum torque is required. In addition, the supplied field current is set at a maximum value during only an initial period when engine starting begins, until the first compression stroke of the engine has been completed, and thereafter set to a reduced value until the completion of engine starting, thereby reducing the amount temperature rise within the field winding during engine starting, while ensuring a sufficiently high value of initial torque.

A particle therapy system capable of increasing the number of patients treated in one treatment room per unit time. The particle therapy system comprises a charged particle beam generator for generating an ion beam, an irradiation apparatus for irradiating the ion beam extracted from the charged particle beam generator to an irradiation target, a beam transport system for transporting the ion beam extracted from the charged particle beam generator to the irradiation apparatus, and a central control unit for producing a set of command data to command excitation currents for magnets disposed in the charged particle beam generator and the beam transport system, the set of command data being classified into group-1 data and group-2 data.

A stepping motor is driven in both closed-loop and open-loop modes while initiating microstepping after a predetermined threshold velocity has been reached. A feedback device such as an encoder is mounted on the stepping motor shaft and the encoder keeps track of the mechanical position of the rotor. Based on feedback from the encoder, stator phases are activated to maintain a 90° phase advance and produce maximum torque. A lead angle compensation technique is used to advance the motor lead angle, to allow for the excitation currents to reach maximum even at higher speeds. The stepping motor controller employs this strategy in order to produce maximum torque across a wide range of motor speeds and actuator motions.

The invention discloses a switch magnetic resistance generator system capable of realizing rapid excitation / demagnetization. The system comprises a switch magnetic resistance motor body, a prime mover, a position sensor, a power converter, a DC power supply and a controller, wherein the power converter is a four-level power converter. By adopting the four-level power converter, at an excitation stage, in an angle position control mode, the exciter current of a phase winding is increased, and the energy storage of a magnetic field is increased so that the output power of an overall power generation system is improved and it is easier for the power generation system to reach a rated power; in an current chopping control mode, the excitation time is reduced, rapid excitation is realized, and the time of a generating stage is increased so that the generating capacity of a motor is enhanced and the output power of the system is increased; and at the generating system, when two voltage sources are utilized, rapid demagnetization can be realized.

Any inspection object regardless of material can easily be inspected or discriminated with high accuracy and high sensitivity by being placed in a magnetic field generated by applying an alternating current to an exciting coil and detecting changes of voltage level and phase of electromotive force induced by a detection coil unit. The discrimination of the inspection object is performed on the basis of a DC voltage value with respect to a standard specimen and a phase differential voltage value with respect to a phase difference between the phase of a voltage signal from the induction coil and the phase of the exciting current to the exciting coil.

A spin-torque oscillator (STO) has a single free ferromagnetic layer that forms part of both a giant magnetoresistance (GMR) structure with a nonmagnetic conductive spacer layer and a tunneling magnetoresistance (TMR) structure with a tunnel barrier layer. The STO has three electrical terminals that connect to electrical circuitry that provides a spin-torque excitation current through the conductive spacer layer and a lesser sense current through the tunnel barrier layer. When the STO is used as a magnetic field sensor, the excitation current causes the magnetization of the free layer to oscillate at a fixed base frequency in the absence of an external magnetic field. A detector coupled to the sense current detects shifts in the free layer magnetization oscillation frequency from the base frequency in response to external magnetic fields.

A transformer unit and a power converting device, which lessen the influence of noise caused by an external magnetic flux, while reducing the temperature dependency of a coupling coefficient, and which transfer signals while insulating a low-voltage and a high-voltage side electrically. Air-core type insulated transformers have a first and second winding of a primary winding as a sending side and a first and second winding of a secondary winding as a receiving side. The windings of the primary winding are connected in parallel and are wound so that the directions of magnetic fields generated by an exciting current oppose each other. The windings of the secondary winding are wound so that electromotive forces to be generated by an external magnetic flux cancel each other, and are connected in series so as to raise the electromotive forces by a signal magnetic flux generated by the primary winding.

In a magnet-exciting rotating electric machine system, a rotor surface has magnetic salient poles and island-shaped magnetic poles alternately in circumferential direction, and the island-shaped magnetic poles are constituted so that magnetic flux coming from an external source does not flow through. A magnetic excitation part magnetizes the island-shaped magnetic poles and the magnetic salient poles collectively in the same direction, and then control a flux amount flowing through an armature. The armature has armature coils that face the magnetic salient pole and the island-shaped magnetic pole simultaneously so that driving torque fluctuation or power generation voltage waveform distortion is controlled. The magnetic excitation part changes magnetization state of a field magnet irreversibly, or changes an excitation current to an excitation coil to control a flux crossing the armature.

A heart monitoring system comprises a ventricular sensing stage sensing excitation or contraction of ventricular myocardium, an activity sensor unit determining a signal reflecting a patient's physical activity, a ventricular impedance or conductance measuring module, said modules comprising a current source unit adapted to provide a sub-threshold excitation current to the myocardium and comprising an impedance or conductance measurement unit for measuring the resulting voltage on said electrode at the myocardium, a signal generator module, a filter module, a memory, a control unit adapted to derive single measures |ΣZ| of magnitude of impedance or conductance change over a preset sample time interval, determine the variability TARVI in the impedance or conductance change, compare this variability and the activity sensor output signal with a threshold and recent history, determine if sleep disturbed breathing (SDB) is present, and log the SDB episode in the memory device.

A system and method for mapping the sensitivity of MR coils includes a neural network or other computer intelligence trained from sample MR data to determine coil sensitivity profiles or sensitivity normalizations. Once the network is trained, subsequent coil mapping determinations may include fewer mapping acquisitions per coil. The resulting sensitivity map can be used in compensating for B1 inhomogeneities, parallel imaging reconstruction, generating tailored excitation currents for each individual coil, RF shimming, or other processes.

A magnetically controlled welding method with consumable electrode features that a pair of exciting coils for upper and lower electrodes are arranged respectively above and under the workpiece to be welded, and an exciting power supply is used to provide the exciting current to said coils and generate an external vertical magnetic field for controlling and perform the welding to the workpiece protected by active gas or CO2. Its welding apparatus has exciting power supply, exciting unit and water cooling system.

An electric motor (10) has a field pole formed by a field current passing through a field winding (50). A voltage booting converter (120) converts output voltage of a battery (B) and outputs the voltage between a power source line (107) and a grounding line (105). Field winding (50) is electrically connected onto an electric current channel between battery (B) and power source line (107) and formed so that voltage switched by a switching element (Q1) is applied to both ends. A controller (100) controls the field current so as to adjust density of magnetic flux between a rotor and a stator by performing switching control on switching element (Q1) and a switching element (Q3) connected in parallel to field winding (50) and converts the output voltage of battery (B) into voltage in accordance with a voltage command value.

The invention discloses a method and a device for multicell joint optimization under coverage of a cellular mobile communication network. The method disclosed by the invention comprises the steps of: collecting the position information of all base stations in a target area; performing grid partitioning on the target area; measuring propagation loss from each base station to each grid point; traversing combinations of total emission power and antenna electrical parameters and making statistics on an adverse coverage ratio; and selecting a combination enabling the adverse coverage ratio to be minimal, and feeding optimal excitation current to each antenna. The device disclosed by the invention comprises an information collection module, a gridding processing module, a propagation loss determination module, a traversing solving module and a selecting module. According to the invention, by means of optimizing directional diagrams and emission power of array antennas to realize the multicell joint optimization orienting to an actual propagation environment under network coverage, the adverse coverage of an entire target area is minimal; and the method and the device not only can be applied to the multicell joint optimization orienting to the actual propagation environment under the network coverage, but also can be used for singly correcting the adverse coverage of exceptional cells.