Tesis
Análise de estabilidade de retificadores com correção de fator de potência empregando modelos lineares periódicos no tempo
Fecha
2012-07-30Registro en:
SCAPINI, Rafael Zanatta. Stability analysis of power factor correction rectifiers employing linear time periodic models. 2012. 200 f. Dissertação (Mestrado em Engenharia Elétrica) - Universidade Federal de Santa Maria, Santa Maria, 2012.
Autor
Scapini, Rafael Zanatta
Institución
Resumen
Many control techniques applied to converters with power factor correction (PFC) use
cascaded control to compensate the output voltage and the input current. These techniques
usually employ linear time-invariant (LTI) models and ignore the periodic output
voltage oscillation by using compensator with low-pass characteristic. To ensure correlation
between the rectifier and its LTI model, as well as power factor correction, these
techniques reduce the crossing frequency, which result in a closed-loop voltage with poor
dynamic response. Aiming to reduce the time-response designers have associated notch
filters into the controller to increase the bandwidth. These filters increase the attenuation
in ripple frequencies making possible to enlarge system bandwidth without compromising
power factor correction. However, increasing the crossing frequency enhances the interaction
between ac output components and the feedback system. In these cases, linear
time-invariant (LTI) approach can not adequately represent the closed loop dynamics. As
a result, LTI stability analysis based on LTI approach is no longer valid. On the other
hand, a better dynamic representation can be achieved by using linear time-periodic models
(LTP). These models include the modulation effects inherent in the output voltage
dynamics. This work presents an alternative systematic methodology to perform the stability
analysis for continuous-time closed-loop control systems using linear time-periodic
(LTP) models. This methodology use an LTP representation in frequency domain called
harmonic transfer function (HTF). This method extends the multi-variable LTI techniques
for LTP approach. Finally is detailed the stability analysis of full-bridge and half-bridge
single-phase PFC rectifiers. Theoretical, simulation and experimental results are presented
to validate the proposed technique.