34results about How to "Reduce DC component" patented technology

An embodiment of the invention is a scalable single stage differential power converter. The inverter can be implemented in signal, split and multi-phases. A multiphase converter can be achieved with only three modules. Integrated magnetics used in preferred embodiments of the invention mitigate the DC component of the steady-state dynamics and can be extended to AC ripple mitigation. Control architectures in preferred embodiments can mitigate higher order harmonics in steady state dynamics. Embodiments of the invention also provide scalability for voltage and current source topologies.

The invention discloses a distributed sensing system based on the differential amplification technology. The system is composed of an optical path detection part and a circuit demodulation part. In an optical path, two different frequencies of microwave signals are modulated to signal light, the frequency of one path of microwave signals is within the Brillouin frequency-shift frequency, and the frequency of the other path of microwave signals is slightly lower than the Brillouin frequency-shift frequency. and in a circuit, a power divider separates the two paths of signals, the separated two paths of signals are filtered and demodulated respectively, and the demodulated signals are amplified in the differential amplification manner. The signals collected by a data collection card are amplified within the specific amplitude interval by the differential amplification structure, and the problems that the range of the data collection card of a host in the distributed Brillouin time-domain analysis sensing system is limited and that the data collection precision cannot be satisfied and further the measurement accuracy of the system is reduced when the DC component is very large are solved. Devices in the system work stably, the point of temperature or stress change and the temperature or stress value can be accurately measured in multiple times of measurement.

The invention provides a micro spherical type short coherent point diffraction interference measurement system and method and belongs to the micro spherical type detection technical field. The micro spherical type short coherent point diffraction interference measurement system and method aims at solving the problems that the contrast ratio of the interference field of the existing short coherent point diffraction interference measurement method is poor and accordingly the measurement accuracy is affected. The micro spherical type short coherent point diffraction interference measurement system comprises a short coherent laser, a first half lambda wave plate, a rectangular reflecting mirror, a polarization splitting prism, a first pyramid prism, a first plane mirror, a second pyramid prism, a PZT (Piezoelectric Ceramic Transducer) phase shifter, a delay platform, a second half lambda wave plate, an optical fiber coupling mirror, a single-mode polarization-maintaining optical fiber, a convergent lens, a pinhole lens, a first collimating lens, a quarter lambda wave plate, a micro-objective, a second plane mirror, a second collimating lens, a polaroid, an area array CCD (Charge Coupled Device) and a computer. According to the micro spherical type short coherent point diffraction interference measurement method, an optical path structure that the quarter lambda wave plate is combined with the polaroid is adopted to select beams in the interference field and accordingly direct current components in the beams are reduced, the contrast ratio of interference fringes is improved, and the adjustable optimization of the contrast ratio is implemented. The micro spherical type short coherent point diffraction interference measurement system and method is applied to the micro spherical type detection.

The invention discloses a detection device and a detection method for carbon monoxide concentration. In the detection device, a first beam splitter splits a light beam emitted by a light source into acalibration light beam and a detection light beam; the calibration light beam is irradiated to a photoelectric detector after passing through a collimator and a calibrated absorption cell to obtain acalibrated electrical signal; a second beam splitter splits the detection light beam into a reference light beam and a measurement light beam; the reference light beam is irradiated to the photoelectric detector after passing through the collimator to obtain a reference electrical signal; the measurement light beam is emitted from the center of a Fresnel lens after passing through the collimatorand is irradiated to a reflecting end after passing through a to-be-detected area, and the reflecting end reflects the light beam to the photoelectric detector from an original path to obtain a measurement electrical signal; a differential amplifier performs differential operation on the reference electrical signal and the measurement electrical signal to obtain a differential signal; a processordetermines the carbon monoxide concentration in the to-be-detected area according to the calibration electrical signal, the reference electrical signal and the differential signal. The detection device and the detection method disclosed by the invention can improve the detection accuracy of laser spectrum measurement of the carbon monoxide concentration in an open area.

The invention relates to a wide-dynamic range pulse blood oxygen measurement system, which is mainly technically characterized by comprising a double-beam light-emitting unit, a pre-detection amplification circuit, a direct current elimination circuit, a buffer amplification unit, a central processor module and an output module, wherein the central processor module is connected with the double-beam light-emitting unit, the pre-detection amplification circuit, the direct current elimination circuit, the buffer amplification unit and the output module respectively; the pre-detection amplification circuit, the direct current elimination circuit and the buffer amplification unit are sequentially connected. The system is reasonable in design; two paths of light transmitted through the tail ends of tissues are added to the digital feedback direct current elimination circuit after being sampled, measured and pre-amplified, so that the intensity of photoelectric signals is improved, direct current components in the signals are reduced in a digital feedback way to realize the synchronous amplification of double-beam signals in a wider range and increase the signal to noise ratio, and the dynamic range of signal detection is widened.

Systems and methods to provide a low voltage interface coupleable between an energy storage device or a DC power source (e.g., fuel cell stack, battery) and one or more AC signal diagnostic systems. The low voltage interface reduces a voltage of the DC power source and supplies the reduced voltage to the one or more AC signal diagnostic systems without affecting the results of the measurements obtained by the one or more AC signal diagnostic systems. Such functionality provides a safer method for performing advanced analysis (e.g., EIS, frequency analysis) while utilizing lower cost and/or smaller components.

An optical encoder comprises a plurality of first photodiodes, a second photodiode and a circuit. The plurality of first photodiodes are arranged in a first direction, each of the first photodiodes has a light detecting part extending along a direction substantially perpendicular to the first direction. The second photodiode is arranged near tips of the first photodiodes, and has a light detecting part extending along the first direction. The circuit performs a calculation based on outputs of the first and second photodiodes.

The invention discloses an excitation power circuit of a rotary transformer, belongs to the field of drive power sources, and solves the problems of complex circuit and incapability of independently working in the traditional excitation power of the rotary transformer. The excitation power circuit consists of a sinusoidal oscillation circuit, an amplitude adjusting circuit and a power amplifying circuit, wherein the sinusoidal oscillation circuit consists of a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a capacitor C1, a capacitor C2, a capacitor CSEL1, a capacitor CSEL2, a first operational amplifier and a second operational amplifier; the amplitude adjusting circuit consists of a resistor R6, a resistor R7, a resistor RSEL, a capacitor C3 and a third operational amplifier; and the power amplifying circuit comprises a resistor R8 and a power amplifier. The frequency of a sinusoidal excitation power source generated by the circuit of the invention is modulated by selecting a capacitance value of the capacitor CSEL1 and the capacitor CSEL2, and the amplitude value of the sinusoidal excitation power source is adjusted by changing the resistance value of the resistor RSEL. The excitation power circuit of the invention serves as the drive power source of the rotary transformer.

A method is provided for encoding the modulation code of high-density optical disk. The character is as follow. The run length is 1 to 10 and the code rate is 4/6. Add DC control bit in the source data to increase the capacity of controlling direct current component. There are 21 meeting the d-k demand in the 6-figure code letter. 16 code letters are choosed as basic code letters to compose the basic code table, and in 5 code letters left the one whose head and end are both 0 is used as connector. Alternative table is made up of basic code letters and connectors, the length of which is 56. The cascade collision problem of code letters is settled by forward looking encoding. If there is cascade collision between code letters through current and forward looking data modulation, the 2 groups of code letters are replaced by the ones in the alternative table; otherwise, modulate the current data. It has higher capacity and encoding efficiency than DVD. The capacity of single side and double layer is up to 13G. It can meet the demand of high definition video programmes. Furthermore, its direct current component is acceptable; the biggest DSV is 2 times of DVD; the code rate is 33.3% higher than DVD; encoding efficiency is one percentage point higher than DVD.

The invention relates to the field of current detecting methods, in particular to a method for processing current static deviation of a permanent magnet motor. The method for processing current static deviation of the permanent magnet motor comprises an initializing step and a current detecting step which are carried out successively, and is characterized in that after current is detected, current static deviation is calculated, and current is sampled during initialization so that i0 is measured; i' is measured when the current is detected; and an actual value of the current is obtained when the current static deviation is calculated. The method has the advantages that required equipment is simple, steps are simple, precision is high, and application range is wide.

The invention provides a short-circuit current providing method and system for a grid-connected converter, and the method comprises the steps: M1, when a power grid is short-circuited, setting and calculating a reference power during a fault period of the converter through a power instruction; M2, on the basis of the reference power during the converter fault period, calculating a virtual electromotive force through a self-synchronizing voltage source type control strategy; M3, obtaining a current reference value under the two-phase static coordinate system through calculation based on the virtual electromotive force and the virtual electronic impedance obtained through calculation of the self-synchronizing voltage source type control strategy, obtaining a converter reference voltage signal through a current control inner ring and power grid voltage feedforward control, and obtaining a converter modulation signal through a modulation link; and M4, controlling the output voltage of the converter according to the converter modulation signal, and further controlling the short-circuit current of the grid-connected converter during the power grid fault period. According to the invention, a current loop is embedded in a voltage source type control strategy, and the control strategy does not need to be switched before and after a system fault.

A direct conversion receiver for receiving a first input signal and directly downconverting it to baseband frequencies. The receiver includes a frequency translator which is responsive to a phase-split input signal having 2n components, wherein n is an integer greater than 1. The phase-split signal has a period T which is about n times the period of the first input. The frequency translator alternates, at a rate of about 2n/T, between switching the first input signal to a first output, and switching the first signal to a second output. A preprocessor is available to improve the switching characteristics of the phase-split input signal.

The method includes steps: using sub band mapping to map modulation symbols to pointed sub band for transmission; next, through IDFT transform to form signal of multiple sub bands (MSB) in time domain (TD); then, through phase shifting and periodic expand to form signal of MSB with shifted frequency and expanded cycle in TD; carrying out waveform shaping and frequency spectrum shaping signal of MSB in TD; finally; using shifted overlap carries out waveform multiplexing in TD for shaped waveform symbol so as to form transmission symbol. The receiver of the filter set in MSB divides up the received data sequence into multiple data blocks, and each data block is equal to length of prototype filter; and then, carries out operations including waveform matching, phase shafting, DFT etc for the data block so as to obtain data symbol transmitted on pointed sub band. The invention can implement transmitting and receiving signal of multicarrier transmission system based on filter set in MSB.

The invention discloses a built-in hybrid excitation bilateral magnetic channel linear motor, and relates to the technical field of linear motors. The linear motor comprises bilateral secondary stators and a primary mover arranged between the stators. The primary mover comprises six primary mover units, and magnetic barriers exist between the primary mover units. Each mover unit comprises two H-shaped magnetic conductive iron cores, and built-in permanent magnets are arranged at the bridge arm positions of the H-shaped magnetic conductive iron cores. Two groups of armature winding mounting grooves and one group of excitation winding mounting grooves are respectively formed in the two ends of the primary mover unit. Each secondary stator comprises a stator yoke and secondary teeth. The bilateral secondary stators are fixed parts, the primary mover is a moving part, and the primary mover performs linear motion in the middle of the bilateral secondary stators, so that the linear motion motor with a bilateral flat plate structure is formed. The linear motor has the advantages of being low in manufacturing cost, symmetrical in flux linkage structure, small in direct current component, small in harmonic component, large in thrust density and the like.

The invention discloses a signal processing method and system for underwater communication and electronic equipment, and the method comprises the steps: enabling a first terminal to receive to-be-transmitted data, carrying out the format conversion of the to-be-transmitted data, and obtaining converted data; after frame synchronization processing is carried out on the converted data, carrying out the Manchester coding on the processed data, and obtaining and sending coded data to the second terminal; after the second terminal receives the coded data, performing Manchester decoding on the coded data and performing frame synchronization search on the decoded data to obtain converted data; and performing format inverse conversion on the converted data to obtain data to be transmitted. According to the invention, the error-tolerant rate of the system is improved through error correction coding and decoding and addition of the synchronization sequence; the system is pre-equalized through 8B/10B and Manchester coding and decoding, the direct current component of the system is reduced, the stability of the system is improved, and the error-tolerant rate is also remarkably improved.