203 results about "Maximum phase" patented technology

The ability of an ultrasonic system to sweep and lock onto a resonance frequency of a blade subjected to a heavy load at startup is improved by applying a high drive voltage or a high drive current while systematically increasing the level of the applied signal. Increasing the drive signal to the hand piece results in an improved and more pronounced “impedance spectrum.” That is, under load, the increased drive signal causes the maximum phase margin to become higher and the minimum/maximum impedance magnitude to become more pronounced. Increasing the excitation drive signal to the hand piece/blade at startup significantly alleviates the limiting factors associated with ultrasonic generators, which results in an increase of the maximum load capability at startup.

A three-phase DC motor output stage including a predriver that supplies drive voltages to power MOSFETs supplies output voltages to three-phase coils, monitors whether each of gate-to-source voltages of the power MOSFETs is greater than or equal to a predetermined voltage and thereby detects a current zero cross, and employs the output of such current zero cross detection in PLL control for controlling energization switching timing and thereby forms drive voltages of 180-degree energization. Lower hooks with a voltage minimum phase as GND and upper hooks with a voltage maximum phase as a source are set as patterns alternately repeated for every electrical angle of 60 degrees. The patterns are expressed in linear approximation to generate sine wave-like drive voltages, thereby causing sine wave-like currents to flow into the three-phase coils.

A method for operating a metal detection system that comprises a balanced coil system. One embodiment of the method comprises: determining the phase and magnitude of related signals at least for a first metal contaminant for at least two transmitter frequencies and for at least two particle sizes of the first metal contaminant; determining the phase and magnitude of the related signal for a specific product for the at least two transmitter frequencies; comparing information established at least for the first metal contaminant and the information established for the product; determining a transmitter frequency with which signal components of smallest sized particles of the at least first metal contaminant differ sufficiently or most in phase and amplitude from the phase and amplitude of the product signal; and selecting the transmitter frequency for measuring the product. A metal detection apparatus adapted to operate according to an exemplary method is also provided.

The invention discloses an amphibious robot propelled by undulating fins. The amphibious robot propelled by the undulating fins is characterized by comprising a robot body, driving arm units and the undulating fins; seven driving arm units are arranged on the left and right sides of the robot body; one ends of the driving arm units are connected with the robot body, and the other ends of the driving arm units are connected with the undulating fins; the undulating fins are formed by bending fan-shaped planes; a phase difference between the undulating fins connected with the two adjacent drivingarm units can be freely adjusted according to coordination between the driving arm units, and the maximum phase difference is 120 degrees; the driving arm units control the undulating fins to performsinusoidal undulation; the robot moves on the land through static friction forces between the undulating fins and the ground and moves underwater through the undulating fins and a counter-acting force of pushing water flow; and compared with a traditional amphibious robot, the amphibious robot propelled by the undulating fins has the advantages of simple structure, convenient control, high energyefficiency, low noise and high movement performance.

Methods and systems for receiving an optical signal using cascaded frequency offset estimation. Coherently detecting an optical signal includes compensating for a coarse laser frequency offset between a transmitting laser and a local oscillator laser by determining a maximum phase error (MPE) in the optical signal, compensating for a residual laser frequency offset between the transmitting laser and the local oscillator laser, and decoding data stored in the optical signal.

The invention belongs to an imaging method for nonlinear frequency modulation label change in the synthetic aperture radar imaging technology, which comprises the steps of two-dimensional frequency domain unfolding, filtering processing, nonlinear frequency modulation label change, distance compression, distance migration correction, rest phase compensation and position compression. In the method of the invention, the characteristics of orthogonality and minimum square error of the Legendre polynomials are utilized for carrying out three-order unfolding on the two-dimensional frequency domain signals of the obtained echo signals according to the Legendre orthogonality polynomials, and then, the focusing imaging on targets is realized through carrying out filtering processing and the like on three-order phase items in echo signal two-dimensional frequency domain expression. When the method of the invention is adopted, the maximum phase error under the same condition is less than 0.2 percent of the maximum phase error in the prior art, so the assurance is provided for the high-precision imaging under the large-inclination view angle condition. Therefore, the method of the invention has the characteristics that the phase error in the imaging process can be effectively reduced, the imaging processing of the large-inclination view angle is realized, in addition, the imaging effect is good, the imaging processing efficiency and the precision are high, and the like.

The invention relates to a method for selecting a fault phase of an alternating current transmission line by using transient energy. The method comprises the following steps of: when the alternating current transmission line fails, extracting a fault component of a three-phase current travelling wave after the fault, and constructing zero mode current and line mode current; performing wavelet transform on phase current and mode current respectively, and solving the transient energy; if the energy value of a zero mode is less than 1 percent of the maximum mode energy value, determining that the fault is a phase-to-phase fault, and otherwise, determining that the fault is an earth fault; if the energy value of a certain phase current is more than 20 percent of the maximum phase current energy value, determining that the fault is the fault phase; and if the fault is the phase-to-phase fault and the energy values of the other two-phase current are less than 20 percent of the maximum phasecurrent energy value, determining that the fault is a three-phase fault. In the method, a phase selection judgment basis is relatively simple, has relatively high applicability to transition resistance and fault initial angles, and can provide a correct basis for the tripping of a breaker in the consideration of combined reclosing at any fault initial angle.

A method for detecting a magnetizing inrush current of a transformer includes the steps of obtaining a difference current for each AC phase of a transformer and calculating, for each AC phase, at least two factors for waveform symmetry recognition, on the basis of the difference currents obtained within one period. For each type of factor, one obtains the maximum value of the three factors corresponding to the three AC phases, to serve as a maximum phase factor of that factor. Based on the maximum phase factor obtained, a waveform symmetry recognition algorithm is used to calculate a corresponding waveform symmetry parameter, and if the waveform symmetry parameter meets a requirement for waveform asymmetry, then it is determined that a magnetizing inrush current has occurred. A device for protecting the transformer is further provided.

Digitally controlled delay-locked loops can have a phase detector, control logic, and a delay chain. The control logic generates digital signals in response to an output signal of the phase detector. The delay chain generates a delay that varies in response to the digital signals. In some embodiments, the control logic maintains logic states of the digital signals constant in response to an enable signal to maintain the delay of the delay chain constant in a lock mode of the digitally controlled delay-locked loop. In other embodiments, the delay of the delay chain varies by a discrete time period in response to a change in logic states of the digital signals, and the maximum phase error between a phase of the reference clock signal and a phase of the feedback clock signal is less than the discrete time period when the digitally controlled delay-locked loop is in a lock mode.

A spatial terahertz wave phase modulator based on the high electron mobility transistor is provided. The phase modulator combines the quick-response high electron mobility transistor with a novel metamaterial resonant structure, so as to rapidly modulate terahertz wave phases in a free space. The phase modulator includes a semiconductor substrate, an HEMT epitaxial layer, a periodical metamaterial resonant structure and a muff-coupling circuit. A concentration of 2-dimensional electron gas in the HEMT epitaxial layer is controlled through loading voltage signals, so as to change an electromagnetic resonation mode of the metamaterial resonant structure, thereby achieving phase modulation of terahertz waves. The phase modulator has a phase modulation depth of over 90 degrees within a large bandwidth, and a maximum phase modulation depth is about 140 degrees. Furthermore, the phase modulator is simple in structure, easy to machine, high in modulation speed, convenient to use, and easy to package.

A piezoactuator has a diaphragm, and the diaphragm has flat piezoelectric elements that oscillate in a longitudinal oscillation mode and a sinusoidal oscillation mode. A first electrode for detecting oscillation in the longitudinal oscillation mode, and a second electrode for detecting the amplitude of oscillation in the sinusoidal oscillation mode, are disposed on the surface of the diaphragm. When the piezoactuator is driven with a drive signal, the phase difference of a first detection signal output from the first electrode and a second detection signal output from the second electrode is detected. The frequency at which the detected phase difference becomes the maximum phase difference is then obtained, and a drive signal of a matching frequency is applied to the piezoelectric elements.

The invention relates to the technical field of variable frequency control, in particular to a current sampling method for a frequency converter, comprising: when performing current sampling during phase sampling, detecting and sequencing the phases of a three-phase voltage, and determining a voltage maximum-phase signal, a voltage middle-phase voltage and a voltage minimum-phase signal; performing current sampling of the current vector information corresponding to the voltage middle-phase signal and the current vector information corresponding to the voltage minimum-phase signal, wherein thecurrent vector information corresponding to the voltage maximum-phase signal is an inverted phase of the sum of the current vector information corresponding to the voltage middle-phase signal and thecurrent vector information corresponding to the voltage minimum-phase signal. In the method provided by the invention, the problem that a current sampling dead zone exists in two recent sampling modes is solved, and synchronously current sampling precision is guaranteed by adopting a two-phase PWM (pulse-width modulation) modulation mode.

An apparatus and method for implementing an equalizer which (1) combines the benefits of a decision feedback equalizer (DFE) with a maximum-a-posterori (MAP) equalizer (or a maximum likelihood sequence estimator, MLSE) (2) performs equalization in a time-forward or time-reversed manner based on the channel being minimum-phase or maximum-phase to provide an equalization device with significantly lower complexity than a full-state MAP device, but which still provides improved performance over a conventional DFE. The equalizer architecture includes two DFE-like structures, followed by a MAP equalizer. The first DFE forms tentative symbol decisions. The second DFE is used thereafter to truncate the channel response to a desired memory of L₁ symbols, which is less than the total delay spread of L symbols of the channel. The MAP equalizer operates over a channel with memory of L₁ symbols (where L₁<=L), and therefore the overall complexity of the equalizer is significantly reduced.

The invention discloses a switched reluctance motor flux linkage characteristic measurement method, which includes the following steps: a position sensor is calibrated, and the coefficient of a measuring circuit is determined; a load is removed, a switched reluctance motor is operated, and the switching angle is adjusted, so that the phase current of the motor is similar to the shape of a flat-topped wave; the direct-current voltage is decreased, so that the peak value of the phase current is as small as possible, and a data matrix is sampled and stored; the direct-current voltage is increased, so that the peak value of the phase current is slowly increased; the load is added, the turn-on angle or the turn-off angle is changed, a needed data set is detected, and the data are sampled and stored; and the peak value of the current is gradually increased until reaching the upper limit of the current allowed by the motor, and data vectors are recorded under different currents until the maximum phase current reaches a maximum current imax needing a current peak value. The whole process of the method only uses the conventional switched reluctance motor speed regulation system and the conventional storage type digital oscilloscope, and does not need a specialized mechanical rotor positioning and clamping device, and the measuring equipment can be easily obtained.