Analysis and Control of PWM Buck-Boost AC Chopper Fed Single-Phase Capacitor Run Induction Motor

Single phase capacitor-run induction motors (IMs) are used in various applications such as home appliances and machine tools; they are affected by the sags or swells and any fault that can lead to disturb the supply and make it produce rms voltage below or above the rated motor voltage, which is 220V. A control system is designed to regulate the output voltage of the converter irrespective to the variation of the load and within a specific range of supply voltage variation. The steady-state equivalent circuit of the Buck-Boost chopper type AC voltage regulator, as well as the analysis of this circuit are presented in this paper. Switching device for the regulator is an IGBT Module. The proposed chopper uses pulse width modulation (PWM) control technique to chop the input voltage into segments in order to guarantee rated rms voltage supplied to the load, which is capacitor-run induction motor. Proportional integral (PI) controller is used to obtain very small steady state error, stable and fast dynamic response, and robustness against variations in the line voltage. The complete system is simulated using software package, and the results are obtained to verify the proposed control method

Mathematical modelling and control of a cost effective AC voltage stabiliser

AC voltage regulation is required in both domestic and industrial sectors to avoid undesired effects from random voltage variations of the power supply. The paper introduces an AC Voltage Stabiliser/Converter (ACVS) that is based on a controllable auto-transformer technology. The proposed ACVS offers a specified strategy of voltage regulation, less harmonics and low cost. The paper explains the operating principle of the ACVS and derives its nonlinear mathematical model. To ensure the desired performance of the ACVS while it is subject to uncertain input voltage and load variations, an optimal control strategy is designed. It is achieved via transforming the ACVS model extending with fictive axis emulation into a rotating reference frame and linearisation of the model via specific orientation of the reference frame and introducing a linear control action. Operation of the ACVS is simulated under different disturbances due to load and grid voltage changes, and compared to voltage stabilisation with application of I and PI controllers. Experimental results are presented to demonstrate the voltage regulation technology

High-Efficiency Line Conditioners With Enhanced Performance for Operation With Non-Linear Loads

This paper presents the analysis, design, and experimental performance verification of a serial type line conditioner. Since it processes only a fraction of the load power, the overall converter losses tend to be lower and the efficiency of the conditioner higher. Regarding the dynamic performance, the line inductance, which results in a positive zero in the transfer function of the plant, is taken into consideration when designing a voltage controller with higher bandwidth for faster response. In addition, a virtual resistance is included in the control of the system to damp oscillations often seen for operations at light load and with nonlinear load conditions. Experimental results obtained with a 10 kVA prototype of a serial line conditioner fed from the load side and the proposed feedback control scheme are presented to demonstrate the superior performance of the line conditioner

A PWM buck-boost AC chopper solving the commutation problem

A novel pulsewidth modulation buck-boost ac chopper using regenerative de snubbers is proposed and analyzed. Compared to the previous buck-boost ac choppers, ac snubbers causing power loss are eliminated using regenerative de snubbers. Experimental results show that the proposed scheme gives good steady-state performance of the ac chopper, which coincides with the theoretical results.1139sciescopu

A PWM buck-boost AC chopper solving the commutation problem

A novel pulsewidth modulation buck-boost ac chopper using regenerative de snubbers is proposed and analyzed. Compared to the previous buck-boost ac choppers, ac snubbers causing power loss are eliminated using regenerative de snubbers. Experimental results show that the proposed scheme gives good steady-state performance of the ac chopper, which coincides with the theoretical results.

Energy saving through voltage optimisation & non-intrusive load monitoring in domestic house

Energy consumption worldwide in domestic domain accounts for almost one third of the total energy consumption so it is important to reduce energy usage in this sector for energy sustainability. The project aims to investigate two domestic energy saving methodologies in domestic sector, namely voltage optimisation and non-intrusive load monitoring. The first method is to address the issues of unnecessarily extra usage of electrical energy caused by excessively high mains voltage. It is achieved via a voltage optimiser to maintain the voltage at a desired constant level. The second method is to make electrical energy usage information more transparent to consumers and identify the potential energy waste caused by misusing energy of devices. This is to be achieved via the methodology of load disaggregation. The mains voltage delivered to individual houses varies constantly depending on the location of the house, the load condition and other factors. The method of installing voltage optimiser in domestic houses to optimise the voltage and reduce energy consumption started from last decade. Most of the existing voltage optimisers do not have very precise voltage control and there is very limit report on the theoretical analysis of them. Therefore, a power electronic based voltage stabiliser for voltage optimisation in domestic house is proposed in this project and an intensive study of proposed voltage stabiliser is carried out in terms of the topology, mathematical modelling and control strategy design. The simulation and experiment results are also presented to verify the proposed voltage stabiliser in this thesis. The current method adopted for analysing energy saving is via comparing the electricity bill of a house before and after the installation of a voltage optimiser. But it is impossible to ensure that the user behaviour and energy usage pattern are exact same in these two cases. The lack of quantitative analysis on energy saving has become a major obstacle to convince people and promote the voltage optimisation in domestic house. This project investigated a method for estimating the energy saving of installing a voltage optimiser in real time. An energy saving algorithm is presented and implemented. A test rig hosting different types of electric loads is established to verify the robustness of this algorithm. The experiment results demonstrate that the presented algorithm can estimate the energy saving achieved by a voltage optimiser in real time with very high accuracy. Non-intrusive load monitoring is to disaggregate the total electricity consumption into individual appliances based on the voltage and current measurement at premise level. Most of the existing approaches require massive training and pre-known dataset to obtain the disaggregated energy breakdown of a house and there is no well accepted approach to monitor the home appliances operation in real time. The project is to explore a new method by which the operations of individual appliances can be monitored in real-time simultaneously. A new load signature is proposed to describe the features of appliances and an event based algorithm is developed in this project. The algorithm is then implemented onto a test rig with 6 different appliances and 11 working modes. The evaluation results demonstrate that the proposed algorithm is able to monitor the operations of individual appliances and feedback the information in real time

Measurements, Models, Systems and Design

531 s.

Estabilizadores de tensão alternada para alimentação de cargas não-lineares: estudo de variações topológicas e métodos de controle

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Engenharia ElétricaNeste trabalho aborda-se o estudo de estabilizadores de tensão alternada que possuem a capacidade de disponibilizar na saída uma tensão com amplitude e forma de acordo com uma referência pré-determinada. Através de uma ampla revisão bibliográfica dos conversores CA-CA faz-se uma classificação dos mesmos e generaliza-se o conceito de compensação série de tensão. Uma topologia de conversor CA-CA indireto sem elementos armazenadores de energia no barramento é escolhida e estudada em todos os seus detalhes, desde o estágio de potência até as possíveis formas de controle da mesma. Na metodologia de projeto do estágio de potência é levada em conta a modelagem da carga não-linear e da tensão de entrada distorcida. As implicações no controle do conversor na presença de impedância de linha são estudadas e, sugere-se a utilização de um filtro de entrada para possibilitar a utilização do controle por realimentação instantânea da tensão de saída, juntamente com um controlador com resposta dinâmica rápida. Os resultados experimentais validam os estudos teóricos realizados, além de corroborar algumas hipóteses discutidas no decorrer do trabalho