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Current sensor

About: Current sensor is a research topic. Over the lifetime, 18957 publications have been published within this topic receiving 147433 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors developed a family of low-noise superconducting quantum interference devices (SQUIDs) for high-speed direct-coupled flux-locked loop (FLL) electronics.
Abstract: We have developed a novel family of low-noise superconducting quantum interference devices (SQUIDs) to cover a wide range of applications. These sensors are robust and easy to use without compromising noise performance. They are optimized for operation with our high-speed direct-coupled flux-locked loop (FLL) electronics XXF-1. For the readout of cryogenic detectors, series arrays of 16 SQUIDs with 3 nH input inductance were designed which can be cooled down and operated in the Earth's field without magnetic shield. A compact gradiometric design allows the chips to be mounted directly on a Cu block at the cold stage of a mK cryostat without degradation in noise. A current noise level of 9 or 5 is achieved at 4.2 K or 300 mK, respectively. Ultra-high-speed operation was demonstrated by using a cold FLL electronics prototype in close proximity to the SQUID array. An extremely high FLL bandwidth of 350 MHz was achieved which outperforms any flux-locked SQUID before by more than an order of magnitude. For applications requiring a larger input inductance of up to 2 , integrated two-stage sensors were developed consisting of a single front-end SQUID with double-transformer coupling read out by a 16-SQUID array. These sensors are very convenient to use as their voltage-flux characteristic is essentially single-SQUID-like. Devices optimized for 4.2 K operation have a coupled energy resolution around 50 times Planck's constant . Heavily shunted devices for low-temperature operation typically achieve 80 or 8 at 4.2 K or 300 mK, respectively. An optional current limiter (Q-spoiler) at the input reduces the input current in pulsed applications like nuclear magnetic resonance or magnetorelaxometry. Integrated rf filters and resistor-capacitor shunts across the input coil result in smooth, well-behaved voltage-flux characteristics even at low temperatures 4.2 K. For magnetic field sensing applications, integrated miniature multiloop magnetometers were designed with maximized field resolution. For a 3 mm 3 mm chip size, a noise level of 3.6 is obtained at 4.2 K.

330 citations

Patent
TL;DR: In this article, a high frequency power supply for applying electrical energy to a target site on or within a patient's body includes an electrical output driver, an output current sensor detecting the current output from the driver, and a power limiting device coupled to the current sensor during normal conditions.
Abstract: A high frequency power supply for applying electrical energy to a target site on or within a patient's body includes an electrical output driver, an output current sensor detecting the current output from the driver, and a power limiting device coupled to the current sensor during normal conditions, the power limiting device operates on a continuous basis. When current output exceeds a predetermined threshold level, the power limiting device is adapted to reduce power on the output driver to a standby mode. The power limiting device operates on a periodic detection or duty cycle when in the standby mode. The power limiting device switches into the stand-by mode to prevent excessive power drains. The power supply operates at a low power, pulsatile manner when an attached probe is in conductive or isotonic fluid but is not engaging body tissue or near a high impedance source. In this pulsatile mode, the power supply operates in a cyclical manner, typically at a predetermined duty cycle.

294 citations

Journal ArticleDOI
TL;DR: The sliding-mode observer for the solar array current has been proposed to compensate for the parameter variations and the experimental results verify the validity of the proposed method.
Abstract: A new maximum power point tracker (MPPT) for a grid-connected photovoltaic system without solar array current sensor is proposed. The solar array current information is obtained from the sliding-mode observer and fed into the MPPT to generate the reference voltage. The parameter values such as capacitances can be changed up to 50% from their nominal values, and the linear observer cannot estimate the correct state values under the parameter variations and noisy environments. The structure of a sliding-mode observer is simple, but it shows the robust tracking property against modeling uncertainties and parameter variations. In this paper, the sliding-mode observer for the solar array current has been proposed to compensate for the parameter variations. The mathematical modeling and the experimental results verify the validity of the proposed method

292 citations

Journal ArticleDOI
TL;DR: In this article, a novel dead-time elimination method for voltage source inverters is presented, which is based on decomposing a generic phase-leg into two basic switching cells, which are configured with a controllable switch in series with an uncontrollable diode.
Abstract: A novel dead-time elimination method is presented in this paper for voltage source inverters. This method is based on decomposing of a generic phase-leg into two basic switching cells, which are configured with a controllable switch in series with an uncontrollable diode. Therefore, dead-time is not needed. In comparison to using expensive current sensors, this method precisely determines the load current direction by detecting which anti-parallel diode conducts in a phase-leg. A low-cost diode-conduction detector is developed to measure the operating state of the anti-parallel diode. In comparison with complicated compensators, this method features simple logic and flexible implementation. This method significantly reduces the output distortion and regains the output RMS value. The principle of the proposed dead-time elimination method is described in detail. Simulation and experimental results are given to demonstrate the validity and features of this new method.

291 citations

Patent
31 Dec 1992
TL;DR: In this paper, the authors present an energy management system consisting of an electronic module (10) which incorporates a microcontroller (12) as a calculation engine and means for controlling various systems of an electric vehicle.
Abstract: The Energy Management System comprises an electronic module (10) which incorporates a microcontroller (12) as a calculation engine and means for controlling various systems of an electric vehicle or other vehicle having limited energy storage. A variety of sensors including battery sensors (18), temperature sensor (20), current sensor (22), temperature sensors (24, 26, 28, 30), speed sensor (32), accelerometer (34), and ignition switch (36) provide information for the Energy Management System to derive control parameters for the systems. Automatic control of heating and air conditioning system (56), external lighting system (58) and the operation of motor controller (54) as well as display of information, status and queries to the driver are controlled by the Energy Management System and range and navigation recommendations are made based on predetermined driving profiles maintained in the system.

275 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202382
2022156
2021273
2020655
2019981
2018970