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2795 results about "Current loop" patented technology

In electrical signalling an analog current loop is used where a device must be monitored or controlled remotely over a pair of conductors. Only one current level can be present at any time. A major application of current loops is the industry de facto standard 4–20 mA current loop for process control applications, where they are extensively used to carry signals from process instrumentation to PID controllers, SCADA systems, and programmable logic controllers (PLCs). They are also used to transmit controller outputs to the modulating field devices such as control valves. These loops have the advantages of simplicity and noise immunity, and have a large international user and equipment supplier base. Some 4–20 mA field devices can be powered by the current loop itself, removing the need for separate power supplies, and the "smart" HART protocol uses the loop for communications between field devices and controllers. Various automation protocols may replace analog current loops, but 4–20 mA is still a principal industrial standard.

Low-loss inductive couplers for use in wired pipe strings

A first flux-loop inductive coupler element electrically couples with a second flux-loop inductive coupler element. The first flux-loop inductive coupler element comprises a first ring-like core having high magnetic permeability and a conical-section annular first face transverse to the plane of the first core. The first face has a first annular groove separating a first conical-section larger-diameter face and a first conical-section smaller-diameter face. A first coil is wound within the annular groove. The first and second cores form a low-reluctance closed magnetic path around the first coil and a second coil of the second flux-loop inductive coupler element.
A first current-loop inductive coupler element electrically couples with a second current-loop inductive coupler element. The first current-loop inductive coupler element has a first high-conductivity, low-permeability shaped belt of a first end of a first pipe joint, a first ring-like core located at the first end, and a first electrically conductive coil wound about the first ring-like core. The first high-conductivity, low-permeability shaped belt partially encloses the first coil. It is shaped to cooperate with the second high-conductivity, low-permeability shaped belt of an adjacent second pipe joint having a second electrically conductive coil and a second high-conductivity, low-permeability shaped belt to create a closed toroidal electrical conducting path. The closed toroidal electrical conducting path encloses the first coil and the second coil when the first and second pipe joints are mated.
Owner:SCHLUMBERGER TECH CORP

Charging system for unmanned aircraft

The invention discloses a charging system for an unmanned aircraft. The charging system is characterized by comprising a power-taking device, an electric energy transmitting device, an electric energy receiving device and an aircraft-mounted battery, wherein an overhead transmission line is arranged on the power-taking device; the electric energy transmitting device is for converting power frequency alternating current into high-frequency alternating current; the electric energy receiving device is arranged on the unmanned aircraft; electric energy transmission is realized in a wireless manner between the electric energy receiving device and the electric energy transmitting device; the aircraft-mounted battery is arranged on the unmanned aircraft, is used for supplying power to the unmanned aircraft, and is connected in series to a current loop of the electric energy receiving device. Compared with the prior art, an electric unmanned aircraft charging system based on an alternating-current power transmission overhead line provided by the invention has the advantages that a full-autonomous and safe charging way is realized for the unmanned aircraft, and the distance per charge of the unmanned aircraft is prolonged. Meanwhile, a high-frequency inductive constant-current charging circuit based on an unstable alternating-current power supply is provided, so that unmanned charging operation is fully realized, the dependence of the unmanned aircraft on a ground base or a mobile base station is reduced, labor operation is reduced, and labor cost is reduced.
Owner:王洋 +3

Electroplastic incremental forming device and method for plates

The invention relates to an electroplastic incremental forming device and an electroplastic incremental forming method for plates. The device comprises a five-axis numerical control forming machine tool, a six-axis parallel robot machining system, a plate forming clamp, a high energy pulse power supply, an infrared thermometer, and a compressed air cooling system embedded in the machine tool, wherein an upper forming pressing head is arranged at the tail end of a spindle of the five-axis numerical control forming machine tool; the six-axis parallel robot machining system is arranged on a working table of the machine tool; the top of the six-axis parallel robot machining system is provided with a lower forming pressing head; the plate forming clamp is fixed on the working table of the machine tool; positive and negative poles of the high energy pulse power supply are connected with the upper forming pressing head and the lower forming pressing head through high current-carrying conductors respectively so as to form a current loop among the high energy pulse power supply, the upper forming pressing head, the lower forming pressing head and the plates; a camera of the infrared thermometer is aligned with a central area of each plate; and the compressed air cooling system is aligned with a forming area of each plate. Compared with the prior art, the invention has the advantages of high efficiency, energy conservation, high machining precision, high surface quality and the like.
Owner:SHANGHAI JIAO TONG UNIV

Permanent magnet motor system with shared bus structure and open winding and control method for suppressing zero-sequence current

ActiveCN103731079ASolve the problem that the back EMF contains the third harmonicTroubleshoot problems with third harmonicsElectronic commutation motor controlVector control systemsFull bridgeElectric machine
The invention discloses a permanent magnet motor system with a shared bus structure and an open winding. The permanent magnet motor system comprises a permanent magnet synchronous motor, two current inverters, a direct-current power supply and a controller. The permanent magnet synchronous motor is of an open winding structure. The current inverters are voltage source type three-phase full-bridge inverters. The direct-current sides of the two current inverters are connected to the same direct-current power supply. Due to the fact that the direct-current sides of the two current inverters are connected directly, three current loops are formed in the structure. The invention further discloses a control method for suppressing a zero-sequence current of the permanent magnet motor system. According to the control method, a voltage compensator is designed for correcting the given voltage of the current inverters so that the zero-sequence current can be reduced substantially. According to the permanent magnet motor system, since the two current inverters share the same direct-current power supply, the structure is simple, cost is low, and operating performance and efficiency are high under the condition that the zero-sequence current is well suppressed.
Owner:ZHEJIANG UNIV

Non-isolated grid-connected inverter and switch control time sequence thereof

The invention provides a non-isolated grid-connected inverter and a switch control time sequence thereof. The non-isolated grid-connected inverter comprises a voltage dividing capacitor branch (1), a clamping branch (2) and a full-bridge basic unit (3), wherein the voltage dividing capacitor branch (1) consists of a first voltage dividing capacitor (Cdc1) and a second voltage dividing capacitor (Cdc2), the clamping branch (2) consists of a first power switch pipe (S1) and a second power switch pipe (S2), and the full-bridge basic unit (3) consists of a third power switch pipe (S3), a fourth power switch pipe (S4), a fifth power switch pipe (S5) and a six power switch pipe (S6). The invention adds two controllable switch pipes and voltage dividing capacitors on the basis of a full-bridge circuit for forming a bidirectional clamping branch, is matched with the switch time sequence, and can realize the battery voltage at a half of the follow current loop potential in the follow current stage, so the leakage current of the non-isolated grid-connected inverter is eliminated, the output current only passes through three switch pipes in the power transmission stage is ensured, and the conduction consumption is effectively reduced.
Owner:NANJING UNIV OF AERONAUTICS & ASTRONAUTICS

Grid-connected current control method for combined single-phase two-stage photovoltaic generation system

The invention discloses a grid-connected current control method for a combined single-phase two-stage photovoltaic generation system. The single-phase photovoltaic generation system is of a two-stage structure and comprises a first-stage BOOST up circuit link and a second-stage single-phase full-bridge inverter circuit link. The single-phase full-bridge inverter circuit link adopts a double-closed-loop control strategy and comprises an outer loop which is a direct-current bus voltage loop and an inner loop which is a grid-connected current loop and further utilizes voltage forward feed control of a power grid. The BOOST up circuit link is used for realizing boosting voltage of a photovoltaic battery module to a direct-current bus voltage reference value while realizing maximum power point tracking. Besides, the single-phase full-bridge inverter circuit link is used for realizing stabilization of the direct-current bus voltage and synchronization of frequency and phase of system output current and voltage of the power grid. The grid-connected current control method for the combined single-phase two-stage photovoltaic generation system has the advantages of excellent stability, flexibility in dynamic response, low content of low-order harmonics, high interference resistance, good robustness, high reliability and the like.
Owner:SOUTHEAST UNIV

PRBS disturbance injection-based power grid impedance online identification method and device

ActiveCN107121609AAvoid Harmonic OscillationCapable of harmonic disturbance injectionElectrical testingImpedence measurementsElectrical engineering technologyGrid connected inverter
The present invention relates to the technical field of electrical engineering and discloses a PRBS disturbance injection-based power grid impedance online identification device. The device is mainly composed of a grid-connected inverter, a current loop controller, a sampling device and an impedance identification unit. The device is characterized in that the grid-connected inverter is connected with the current loop controller. When the grid-connected state is stable, the grid-connected inverter injects the PRBS disturbance into the power grid. During the injection process of a PRBS signal, a built-in output voltage THD is fed back to the controller, so that the THD value of the output voltage of the inverter is ensured to be smaller than 5%. The sampling device is connected with the PCC part of the power grid and is used for sampling and recording the voltage and the current at the PCC part of the power grid. The impedance identification unit is used for subjecting the sampled data of the sampling device to DFT analysis, and taking the average value of the amplitude and the average value of the phase of each harmonic component of the voltage and the current during the current sampling period. The method of the invention is high in precision, high in speed, strong in real-time property, wide in frequency range, lower in measuring cost and difficulty, and better in stability.
Owner:GUANGXI UNIV

Bunched electrode high-speed discharge processing method

The invention discloses a bunched electrode high-speed discharge processing method in the technical field of arc discharge processing. A bunched electrode is fixedly connected with a spindle of a machine tool, the end surface of the bunched electrode faces to a workpiece to be processed on an operating platform of the machine tool, and the workpiece can be immersed in a water-based operating fluid provided by a water-based operating fluid supply system; then a fluid loop is formed by the water-based operating fluid supply system, the bunched electrode and a machine tool operating fluid trough, and a current loop is formed by a discharge source, the bunched electrode, the interelectrode broken-down water-based operating fluid and the workpiece to be processed; the water-based operating fluid between the bunched electrode and the workpiece to be processed is circulated through the water-based operating fluid supply system; the bunched electrode is connected with the negative electrode of the discharge source, the workpiece to be processed is connected with the positive electrode of the discharge source, and direct current or pulse current is applied by the discharge source to form short arc discharge, so that the high-speed discharge processing is realized. The invention realizes strengthened high pressure and large flow fluid filling in multiple holes by utilizing the bunched electrode, ensures short arc discharge processing by applying a fluid hydrodynamic force arc-breaking mechanism and is a method capable of simply, conveniently and economically realizing the high-speed discharge processing of the bunched electrode, particularly the processing of curves and mold cavities.
Owner:SHANGHAI JIAO TONG UNIV
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