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Pulse Modulation by Switches of High Frequency of Alternating Current Circuits and Application of This Method
Abstract
This paper is devoted to analysis of AC pulse modulation systems and calculation method explanation for such systems. Analysis of load filter parameters are performed by regressive estimation of filtering system parameters. The utility of such system has been reviewed in the context of the application of 3-phase induction motor.
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There is need and scope of controlling the power consumed by conventional electric lamps in presence of some natural light. An artificial intelligence based control system has been developed to control a lamp dimmer circuit with bidirectional triode thyristor. The light present in the room is sensed and voltage supplied to the lamp is controlled by varying the time constant of the circuit through change of resistance of a multi-turn potentiometer with a stepper motor. The resistance set in the lamp dimmer circuit is in accordance with signals from an adaptive Neural Network running in MATLAB ®. The artificial neural network (ANN) runs in real time in MATLAB ® environment to control the time constant of the lamp dimmer circuit for controlling of power consumption. Under test conditions, energy savings up to 35% is achieved.
The concept of 4th Industrial Revolution, that is characterized by the increasing digitalization of products and services (Internet of Everything) and interconnection of new business models and value chains, has been a part of our life for a while now. The wide adoption of Information Technology by modern business and public space removes the boundaries between real and virtual worlds and enables new growth possibilities for the industry. Drones, 3D printing, artificial intelligence, nanotechnology, robotics are very few examples of exponentially growing technologies, that are revolutionary changing the business models and industrial processes nowadays, and will shape modern industry fundamentally.
The parameters of electrical energy, such as supply voltage amplitude, are very important, especially from the viewpoint of the final consumer with respect to sensitive loads connected to the grid. Dynamic states in the power grid?voltage sags and swells?might cause faults and defects to develop in sensitive loads. To mitigate unwanted effects, many topologies of ac/ac converters are implemented as voltage compensators. This article presents a review of hybrid ac/ac converters designed to compensate voltage sags and swells with the aim of protecting sensitive loads against sudden and severe changes in supply voltage amplitude. In this article, only solutions without galvanic separation between source and load are described. To assess the properties and to compare different topologies of voltage compensators, some common parameters, such as range of voltage sag and swell compensation, reliability, quantity of switches and transformers, and required power ratings of power electronic units in relation to power of load, are introduced. In addition, we discuss possibilities for compensation of voltage interruption, time of compensation, the efficiency, and the effect on the supply network of the described circuits. The results of the analysis have been collected and compared in tabular form and represented in graphical form. Furthermore, we show potential areas of application for particular solutions of ac voltage compensators.
This paper presents a single phase AC/DC/AC converter based on parallel AC/DC and cascaded multi-level DC/AC Converter. For a two-cell AC/DC/AC converter, two units of full-bridges are connected in parallel and two units of half-bridges are connected in cascade. It is proposed that instead of using two separate control loops of DC link voltages at the AC to DC conversion stage, only a single control loop with only one voltage sensor is proposed in this paper when two cells are equally loaded. It is also shown that by controlling only one cell DC link voltage, the other dc link voltage also gets controlled automatically. In addition, the power factor is also improved to unity at the AC side of the AC/DC conversion stage. Use of simple and unipolar ramp comparison control at both the stages leads to fixed switching frequency operation of all the switches along with the improved quality of input current and output voltage as compared to simple PWM control. The simulation result for the proposed topology has been obtained through the PSCAD/EMTDC simulation studies, for a two-cell based parallel cum cascaded AC/DC/AC converter. The experimental verification of the proposed topology and control strategy has been obtained using LABVIEW FPGA module with the help of PCI-7831R data acquisition board.
The Single-Phase Induction Motor (SPIM) has a high starting current and needs a centrifugal switch to disconnect the auxiliary winding. Using soft starters or single-phase variable speed drivers can properly solve these two problems. However, these solutions are expensive. In this paper we discuss the new topology supply for SPIM using Triacs, called Double Dimmer Supply Method, which focuses on the angle control between the main and auxiliary winding voltages.
Two power bipolar transistors structures called the trench base-shielded bipolar transistor (TBSBT) and Gate Associated Transistor (GAT) were proposed and experimentally demonstrated. Those structures incorporate deep P+ area in the purpose to achieve high current gain without compromising on the breakdown voltage. In this paper, we suggest a new behaviour for a bipolar bidirectional switch with very low on-state voltage drop, and having a fully turn-on/turn-off control for main application. We propose to use two high current gain bipolar power transistors, one to control the forward current, and the second one to short-circuit the complementary diode, thus, for the first time, significantly decrease its power dissipation.
Utility power quality problems like input voltage unbalance and sag conditions severely stress electronic equipment. Voltage sag forecasting is a complex issue, since it involves a large variety of random factors, such as: type of shortcircuits in the power system, location of faults, protective system performance and atmospheric discharges. Recently, the AC-AC converters have been proposed as voltage compensator. In this paper a patented topology is proposed and checked; its main advantage is that in addition to compensate voltage sags or swells by changing the duty ratio, it may be used as a line dimmer for lighting loads.
This paper describes a novel distribution-level voltage control scheme that can compensate voltage sag and swell conditions in three-phase power systems. Faults occurring in power distribution systems or facilities in plants generally cause the voltage sag or swell. Sensitivity to voltage sags and swells varies within different applications. For sensitive loads, even a voltage sag of short duration can cause serious problems. Normally, a voltage interruption triggers a protection device, which causes the shutdown of the entire load. In order to mitigate power interruptions, this paper proposes a scheme for voltage sag support based on a pulse width modulated (PWM) autotransformer. The proposed scheme is able to quickly recognize the voltage sag or swell condition, and it can correct the voltage by either boosting the input voltage during voltage sag events or reducing the voltage during swell events. The key advantage in this voltage boost topology is that it uses only one controlled switch per phase to boost the input voltage, thereby resulting in minimum cost per kVA. The paper presents the new voltage control topology, as well as the voltage detection method, the snubber design, and the commutation logic for the thyristor bypass switch. Experiments have been carried out to verify the validity of the proposed scheme.
This paper presents a soft-switching PWM inverter with auxiliary resonant bridge-leg link snubbers on the basis of bidirectional active power switches and voltage clamping diodes. The voltage clamping diodes protect the bidirectional active switches from spike surge voltage caused by the stray energy of auxiliary inductors and parasitic wiring inductances. From a practical point of view, a variety of resonant snubber circuits with the voltage clamping diodes are also presented, Among the variations of the proposed resonant snubber circuits, emitter-emitter connected type IGBT bidirectional active switch and two clamping diodes type snubber circuit is discussed in detail. Furthermore, the performances of the proposed soft switching PWM inverter with the auxiliary resonant bridge-leg link snubber-associated inverter-fed DC to DC converter is demonstrated and evaluated in order to prove feasibility applying for an X-ray high-power high-voltage application.
In this paper an approach to compensate for voltage sags via a
three-phase AC to AC boost converter is investigated. The proposed pulse
width modulation (PWM) control strategy ensures independent control of
each phase and compensates for both symmetrical and asymmetrical voltage
sag disturbances. Examples from simulation show good compensation for a
50% symmetrical sag and a 65% asymmetrical sag. Experimental result
shows a fast detection and compensation of the disturbances
Power system analysis: The case of Albania
- M Zhuri
M. Zhuri, "Power system analysis: The case
of Albania", International Journal of
Innovative Technology and Interdisciplinary
Sciences -Volume 3, Issue 4, 2020,
https://doi.org/10.15157/IJITIS.2020.3.4.50
1-512, ISSN 2613-7305.