An AC chopper controller with symmetrical Pulse-Width Modulation (PWM) is proposed to achieve better performance for a single-phase induction motor compared to phase-angle control line-commutated voltage controllers and integral-cycle control of thyristors. Forced commutated device IGBT controlled by a microcontroller was used in the AC chopper which has the advantages of simplicity, ability to...

The investigation of short time dynamics using X-ray scattering techniques is commonly limited either by the read out frequency of the detector or by a low intensity. In this paper, we present a chopper system, which can increase the temporal resolution of 2D X-ray detectors by a factor of 13. This technique only applies to amorphous or polycrystalline samples due to their circular diffraction ...

This paper deals with an observer design for a P-Cell Chopper. The goal is to reduce drastically the number of sensors in such system by using an observer in order to estimate all the capacitor voltages. Furthermore, considering an instantaneous model of a p-cell chopper, an interconnected observer is designed in order to estimate the capacitor voltages. This is realized by using only the load ...

The new wide angular-range chopper spectrometer ARCS at the Spallation Neutron Source at Oak Ridge National Laboratory has been successfully used in whitebeam mode, with no Fermi chopper, to obtain neutron powder diffraction based atomic pair distribution functions (PDFs). Obtained PDF patterns of Si, Ni, and Al2O3 were refined using the PDFfit method and the results compared to data collected ...

Since the introduction of monolithic IC amplifiers there has been a continual improvement in DC accuracy. Bias currents have been decreased by 5 orders of magnitude over the past 5 years. Low offset voltage drift is also necessary in a high accuracy circuits. This is evidenced by the popularity of low drift amplifier types as well as the requests for selected low-drift op amps. However, until n...

High current and stringent restrictions on beam losses in the designed linac and storage ring for the Spallation Neutron Source (SNS) require clean and fast – with the rise time from 2% to 98% less than 2.5 ns – beam chopping in the linac front end, at the beam energy 2.5 MeV. The development of new traveling-wave deflecting current structures, based on meander lines, for the SNS fast chopper i...

A low-noise CMOS amplifier operating at a low supply voltage is developed using the two noise reduction techniques of autozeroing and chopper stabilization. The proposed amplifier utilizes a feedback with virtual grounded input-switches and a multiple-output switched opamp. The low-noise amplifier fabricated in a 0.18-μm CMOS technology achieved 50-nV/ √ Hz input noise at 1-MHz chopping and 0.5...

It was reported that the chopper on the MISM would fall out of lock (with its reference) over time, and it was suspected that this was due to changes in the temperature of the motor. Other unusual behavior was also reported such as only being able to achieve lock when the motor speed was increasing towards the desired value and not when a trying to reduce from one speed to another. It was repor...

On the latest accelerated beams, all the RF systems, the axial buncher [2], the three RF cavities of the superconducting cyclotron [7] and the high energy chopper [2], have been driven from the DDS generator. The phase stability, between these components of the RF System [3], is stable in order to ensure the stability on the extracted and choppered beam. With this new generator based on the Dir...