30results about How to "Reduce noise amplitude" patented technology

The invention relates to a rotating speed filtering device and filtering method of a PMSM. The rotating speed filtering device of the PMSM comprises a position sensor, the PMSM, a rotating speed calculating module, a Kalman filtering module, a speed ring PI adjuster, a current sensor, a summation module, a coordinate transformation module, a first current ring PI adjuster, an SVPWM module, a second current ring PI adjuster and an inverter. The position sensor, the rotating speed calculating module and the speed ring PI adjuster form a speed ring. The coordinate transformation module and the current ring PI adjuster form a q-axis current ring. The coordinate transformation module and the current ring PI adjuster form a d-axis current ring, and the q-axis current ring and the d-axis current ring form a current ring. The filtering method based on the rotating speed filtering device of the PMSM can effectively filter the detecting noise of the rotor rotating speed of the PMSM, calculated loads are reduced, and the parameter dependence degree on the PMSM is lowered.

The invention discloses an interleaved parallel three-phase power factor correction (PFC) circuit. The circuit consists of two Vienna converters, wherein the Vienna converters have three-phase three-switch three-level PFC structures; three phase inputs of the first Vienna converter are connected with three phase inputs of the second Vienna converter respectively; three level outputs of the first Vienna converter are connected with three level outputs of the second Vienna converter respectively; the period starting time and the period ending time of three bidirectional switches of the first Vienna converter are the same; the period starting time and the period ending time of three bidirectional switches of the second Vienna converter are the same; and the period starting time and the period ending time of the three bidirectional switches of the first Vienna converter are half period earlier or later than the period starting time and the period ending time of the three bidirectional switches of the second Vienna converter.

The invention discloses a multi-scale ground microseism inverse time interference positioning method. The inverse time positioning and multi-scale variational mode decomposition are combined, the original microseism data is decomposed into multiple scale domains with different vibration characteristics through the multi-scale decomposition technology, the noise amplitude is gradually reduced alongthe increasing of the decomposition scale, the amplitude of the effective signal is gradually increased, the proportion of the background noise can be reduced, and then the precision of the seismic source positioning is improved; furthermore, the original microseism data is decomposition into multiple scale domains through the multi-scale variational mode decomposition, the characteristics of theeffective signals extracted from multiple scales are enhanced, the disadvantage of the sampling information caused by a sparse observation system can be remedied; the product of the effective scale inverse time interference positioning can improve the focusing and resolution of an inverse time interference positioning imaging ellipse, and then an imaging illusion is suppressed.

The invention relates to a method which can effectively eliminate narrowband noise and white noise in the cable local discharging signal. The method comprises steps of signal filtering pretreatment, wavelet threshold noise reduction and deconvolution. The narrowband noise and the white noise whose amplitude and frequency are irregularly changed can be well restrained.

The invention discloses a fiber optic hydrophone remote transmission array system based on compensation interference as well as a method. The system comprises a signal emission unit used for inputtinga pulse signal, a compensation interference unit which has unbalance arm difference and is used for converting the pulse signal into a pulse signal pair with delay and outputting the pulse signal pair with delay, an optical annular unit used for transmitting the pulse signal pair, a time division multiplexing array unit which is provided with a time division multiplexing array and used for splitting and delaying the pulse signal pair, merging all the delayed signals after a sensing signal is acquired and transmitting a time division multiplexing interference pulse signal provided with the sensing signal to a second port of the optical annular unit from an input output port and a signal receiving unit used for resolving the time division multiplexing interference pulse signal to obtain thesensing signal. The system disclosed by the invention can greatly enhance comprehensive performance of a large-scale fiber optic hydrophone remote transmission array, so that the large-scale fiber optic hydrophone remote transmission array can meet application requirements of related fields such as fiber optic hydrophone sealfloor shore-based fixed arrays.

The invention relates to the field of a magnetic core fixing structure assembly of a Hall current sensor, in particular to a magnetic core air gap fixing structure assembly for a core passing type Hall current sensor. The magnetic core air gap fixing structure assembly is characterized in that a fixing hole or a positioning groove is formed in a single magnetic core with an air gap formed by lamination riveting and punching; a non-conductive metal sheet is riveted and punched or welded onto the upper top layer or the outermost upper and lower layers of the single magnetic core; the non-conductive metal sheet is welded onto the outer side surface or the top of the magnetic core air gap position by a single magnetic core with an air gap formed by winding; when the two single magnetic cores with the same dimension or the single magnetic cores with one or even air gaps and one fixing frame or framework is used, the two single magnetic cores with the air gaps are arranged on the upper and lower surfaces of the fixing frame or the framework; the even number of air gaps are in staggered arrangement or symmetrical distribution or uniformly divide the whole magnetic paths; the side surface of the fixing frame or the framework is provided with an insertion groove communicating the air gaps of the magnetic core; the conversion plate is inserted in the insertion groove; a Hall element arranged in the magnetic core air gap is directly connected with a printed circuit board or is connected with the printed circuit board through a conversion plate.

The invention discloses an optical fiber hydrophone array structure based on compensation interference. The structure comprises a signal input end which is used for inputting a pulse signal, a compensation interference assembly which has an unbalanced arm difference and is used for converting the pulse signal into a delayed pulse signal pair and outputting the delayed pulse signal pair, an opticalring assembly used for transmitting the pulse signal pair, a time division multiplexing array assembly which has a time division multiplexing array and is used for splitting and delaying the pulse signal pair, combining delay signals after sensing signals are obtained, and transmitting time division multiplexing interference pulse signals with the sensing signals to a second port of the optical ring assembly from an input/output port, and a signal output end used for outputting the time division multiplexing interference pulse signals with the sensing signals. According to the optical fiber hydrophone array structure, the comprehensive performance of a large-scale optical fiber hydrophone remote transmission array can be greatly improved, and the application requirements of related fieldssuch as optical fiber hydrophone seabed shore-based fixed arrays are met by the large-scale optical fiber hydrophone remote transmission array.

A system and a method of noise mitigation for hybrid and electric aircraft are disclosed, the aircraft having a controllable pitch propeller or rotor(s) with a plurality of blades. The propeller or rotor(s) are driven by a drive system to provide thrust for the aircraft, and the blades of the propeller or rotor(s) are further movable about pivot axis to vary a pitch thereof. A controller on- boardthe aircraft is operable to cause rotation or movement of the blades of the propeller or rotor(s) about their pivot axis to alter and/or focus at least one aspect of the propeller generated noise toreduce or mitigate such noise while maintaining a substantially constant thrust, altitude, and/or air speed of the aircraft.