6 results about "Output impedance" patented technology

The invention relates to a smooth switching control method for an operating mode of a micro-grid inverter of different capacity micro sources. The method is applied to a micro-grid consisting of multiple different capacity micro sources. The method comprises the following steps: by virtue of switching among different switches, realizing smooth switching of an inverter control method under island/grid-connected operating modes, wherein the island operation is controlled by robust V-f based on capacitive equivalent output impedance so as to generate the voltage reference quantity, and the grid-connected operation is controlled by adopting PQ; adding a pre-synchronization link to be used for controlling the inverter output voltage to trace the power grid voltage when the inverter is switched from island operation to the grid-connected operation, and ensuring that the grid-connected operation is smoothly finished; introducing virtual impedance, designing the equivalent output impedance of the inverter to be capacitive, reducing loop current between parallel inverters, and well realizing power distribution among different capacity micro sources; and adopting double-loop control of the outer voltage loop and inner current loop, wherein the outer voltage loop is controlled by PI, and the inner current loop is controlled by dead beat. Therefore, the system is high in stability and high in dynamic response speed.

The invention belongs to the field of production and processing of an attenuation sheet, and specifically relates to a manufacturing method for a 1dB attenuation sheet with power of 2W; the manufacturing method comprises the following steps of designing an attenuation sheet pattern through HFSS software in a simulation manner; sputtering a resistor and an electrode layer on an aluminum oxide ceramic substrate; electroplating a thickened gold electrode; obtaining electrode and resistor patterns through photoetching; dividing the attenuation sheet by a grinding wheel into independent attenuation sheet units; adjusting input and output impedances by a thermal oxidation impedance adjusting method; and coating the input end and the output end of the attenuation sheet with conductive silver paste. By adoption of the attenuation sheet manufactured by the invention, the operating frequency can achieve 18GHz; the attenuation precision within the operating efficiency is 1dB plus or minus 0.4dB; the standing-wave ratio is less than or equal to 1.3; and the input and output impedances are 50 plus or minus 1 omega.

The invention discloses a DFIG impedance remodeling control method and a DFIG impedance remodeling control system without phase-locked loop direct power control. The impedance remodeling control method comprises the following steps: analyzing DFIG impedance high-frequency capacitance characteristics of phase-locked loop-free direct power control according to an equivalent single-input single-output impedance Bode diagram; according to DFIG impedance high-frequency capacitance characteristics of phase-locked-loop-free direct power control, analyzing the generation reason and parameter sensitivity of high-frequency resonance through a DFIG high-frequency simplified model; according to the relationship between the frequency coupling characteristic intensity and the DFIG phase margin of the phase-locked loop-free direct power control, introducing voltage feedforward virtual impedance to carry out DFIG impedance remodeling, and carrying out parameter design; according to the equivalent single-input single-output impedance Bode diagram, analyzing the DFIG phase margin and the remodeling effect after the voltage feed-forward virtual impedance is added. According to the invention, the frequency coupling characteristic of the DFIG system is reduced, the phase margin of the DFIG under the inductive weak power grid is improved, and the high-frequency resonance is inhibited.

An earphone with adjustable impedance is provided. The earphone mainly includes an earphone body, a communication line, an earphone plug, an alter switch and an adjustable impedance unit used for adjusting an impedance of the earphone. The adjustable impedance unit is connected between the earphone plug and the earphone body through the alter switch. The impedance of the earphone can be matched on the output impedance of the media player by adjusting the impedance of the adjustable impedance unit when an earphone is connected with a media player.

The invention discloses an energy recovery device utilizing piezoelectric stack energy harvesting. The energy recovery device comprises a support, a lever amplification assembly connected with the support, a piezoelectric stack arranged between the support and the lever amplification assembly and used for converting mechanical energy of a lever amplification mechanism into electric energy to be output, and a pre-tightening assembly. According to the energy recovery device for capturing energy by utilizing the piezoelectric stack, deformation generated by vibration of the excitation source canbe effectively converted into excitation force acting on the piezoelectric stack through the amplification mechanism, so that the piezoelectric stack generates greater deformation, and energy output is increased; the output current can be remarkably increased, the output impedance of the energy recovery device is reduced, and the energy conversion efficiency is effectively improved; the device hasthe technical advantages of being simple in mechanical structure, convenient to machine and the like, energy can be supplied to an intelligent equipment system through energy collection, and the device has wide application prospects in the fields of wireless technologies and electromechanical systems.