Medição de impedância utilizando sistemas digitais

AUTOR(ES)

Karla da Costa Ribeiro

FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

12/06/2007

RESUMO

Conducting measurements is, in the most part of practical situations, essential for scientific research. It is so important, that it can be said, that all areas in engineering are dependent of it. As well known, impedance measurement is a subject of great interest in many application fields, each of which has different demands in terms of accuracy, range, measurement rate and so on. In order to satisfy these needs and using different techniques, several circuits and instruments have been developed during the last years. This work presents an impedance meter which is capable of operating in real time and monitoring the system fundamental frequency and the unknown impedance without disconnecting the impedance from the circuit. These measurements can be done by acquiring the voltage and current signal of the unknown impedance followed by proper processing which is based on applying discrete time domain techniques like digital filtering, downsampling and the discrete time Hilbert Transform. The developed measurement algorithm was called Complex Impedance Measurement Algorithm CIMA and its robustness was tested and validated computationally through the addition of electrical noise in the voltage and current signals. Experimental tests were performed and the results were compared with the values provided by commercial instruments (a RLC bridge of 0,2% accuracy and a 6,5 digits multimeter). Percent deviations are used to qualify the results and 8 impedances were measured: 3 resistors, 3 capacitors and 2 RC associations. In a complementary test, 3 capacitors were initially measured and 2 of them were retired from the circuit using manual switching during the experiment. This was done in order to evaluate the measurement system capacity in detecting impedance variation and also to evaluate its settling time.

ASSUNTO(S)

engenharia elétrica teses.

Documentos Relacionados

• Desenvolvimento de um sistema automatizado para medição de impedância elétrica
• Previsão de distorções harmonicas em sistemas eletricos de potencia, utilizando-se matriz impedancia de barra harmonica
• Espectroscopia de impedÃncia aplicada a sistemas nanoestruturados e polÃmeros condutores
• Automação da detecção de fraudes em sistemas de medição de energia elétrica utilizando lógica fuzzy em ambiente SCADA
• Simulação lógica hierárquica de sistemas digitais