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Chopper
Published in Vinod Kumar, Ranjan Kumar Behera, Dheeraj Joshi, Ramesh Bansal, Power Electronics, Drives, and Advanced Applications, 2020
Vinod Kumar, Ranjan Kumar Behera, Dheeraj Joshi, Ramesh Bansal
Choppers are the switching converters, which convert unregulated DC input voltage into a controlled DC output at a desired voltage with little power loss. Nowadays, DC-to-DC conversion is becoming very important in different electronic circuit applications. There are many circuits which use DC power at several different voltage levels, such as in battery-operated systems. Duty ratio control or the pulse-width modulation (PWM) is effectively used to control these converters. Various applications where variable DC power (chopper) is required are trolley cars, marine hoists, battery-operated vehicles, battery charging, subway cars, mine haulers etc. Chopper system provides smooth control, high efficiency, and fast response. The power semiconductor devices used for a chopper circuit can be power bipolar junction transistor (BJT), power metal-oxide semiconductor field-effect transistor (MOSFET), gate turn-off (GTO), or forced-commutated thyristor.
dc/dc Converters
Published in K Sundareswaran, Elementary Concepts of Power Electronic Drives, 2019
If the existing input is dc voltage, then a chopper circuit is employed to get a variable dc voltage at the output. A chopper is a power electronic circuit connected between a constant dc voltage source and load. Chopper circuits are also called dc/dc converters. In principle, a chopper is equivalent to a mechanical switch connecting and disconnecting the load from the source at desired intervals. Chopper circuits, usually employing silicon-controlled rectifiers (SCRs), are widely used for speed control of dc motors in industries, electric traction, and battery-powered vehicles. Chopping at high frequency is used in dc power supplies such as buck, boost, and Ćuk converters.
Advanced Motor Controls
Published in Julio Sanchez, Maria P. Canton, Embedded Systems Circuits and Programming, 2017
Julio Sanchez, Maria P. Canton
Although the general concept of a chopper circuit is not very well defined, it can be viewed as a switching operation used to control one signal with a second one. Power supplies, amplifiers, switched capacitor filters, and variable-frequency drives are common uses of chopper circuits. In the context of motor controls, a chopper circuit is one in which a controlled switch is used to limit the current flowing through a coil. The operation requires some way of sensing the current so that the chopper switch can be turned on and off as the predetermined current limits are reached.
Dielectric and thermodynamic studies of n-cyano-biphenyl (nCB) liquid crystals at microwave frequency
Published in Liquid Crystals, 2023
The underlying idea behind the perturbation technique is that the presence of a ‘small’ size dielectric sample inside a resonant cavity causes the shift in the resonant frequency and the cavity’s quality factor falls. Here, ‘small’ means the sample’s volume is considerably smaller than the cavity’s size. The observed changes in frequency and the quality factor of the cavity are used to calculate the complex permittivity of the material under test. Figure 1 is the block diagram of the experimental setup of microwave cavity spectrometer. In this setup, a signal frequency, near cavity resonance, is generated by a reflex klystron by mechanical tuning and setting of voltage. An oscilloscope sends saw-tooth ramp voltage, and a chopper signal of 31 kHz is impressed on the klystron repeller to produce an AC signal of the desired frequency. This chopper signal enables the tuned amplifier to detect the signal by the RF detector. The second derivative of the signal is fed to one channel of the oscilloscope. A signal from the Klystron was sent to the marker mixture along with harmonics of the frequency standard. The two signals are compared by a tuned radio receiver, and the two markers were generated and displayed on the second channel of the oscilloscope. A permanent record of the signal and two markers is taken on dual pen chart recorder. The separation of these markers is set to 4 MHz (Figure 2).
High gain boost converter fed asynchronous motor drive for water pumping system
Published in International Journal of Electronics, 2022
The proposed boost chopper consists of one-switch is introduced. This boost converter is integrated a with positive quadratic high gain cell (PQHGC) boost converters used to obtain a high gain voltage for PV purposes. The advantages of this converter are, reduces voltage stress across the semiconductor switch, low value of inductor inrush current IL1 and minimal output voltage peak time with fast settling time. The circuit configuration of converter is shown in Figure 3. The input voltage [Vin] to the converter is the output voltage of Photovoltaic. the diode-capacitor voltage multiplier, which comprises of a number of cells (each cell contains two equal capacitors and two diodes with output inductor Lo. The investigation of steady state mode is done by utilising the average through the period of the voltages over the capacitors and the currents through the inductors. In this way, it is accepted that the pulsations of these parameters are moderately little.
Modeling and control of a 3-DOF articulated robotic manipulator using self-tuning fuzzy sliding mode controller
Published in Cogent Engineering, 2021
Aderajew Ashagrie, Ayodeji Olalekan Salau, Tilahun Weldcherkos
From the joint torque calculations, the calculated torques at the three joints that are used for lifting the respective joints are 39.6 Nm, 38.9 Nm, and 15.9 Nm for joint one, two, and three, respectively. From the calculated joint torques, the joint actuators were selected from the PMDC motor manufacturer’s catalog of Electrocraft (Yin et al., 2017). This was due to its higher performance, reliability, and adjustable speed control. The dc drives play a vital role in modern industrial drives. Therefore in this paper, a PMDC motor is used to drive all joints of the robotic manipulator, and the speed control of the dc motor was obtained by using a chopper as a converter to vary the armature voltage. The performance of the DC machine improved due to the use of the dc chopper, making it an essential component for rapid transit systems. Figure 3 shows the DC motor (Sahin, 2005).