| Abstract |
The paper analyses the stability limitations of the digital dead-beat current control applied
to voltage-fed three-phase converters used as PWM rectifiers. In particular, attention is focused on the
interactions between the rectifier and the input filters, which are commonly employed to eliminate the
high frequency harmonic content from the line currents. The effects of the inherent model mismatch
represented by the input filters, which are not normally included in the conventional dead-beat
algorithm, are analysed by developing a detailed stability analysis, based on a discrete-time state
space model of the controlled system. The proposed analysis allows to predict the occurrence of
unstable conditions and to identify some control refinements improving the system's robustness. The
results of the theoretical analysis and the validity of the proposed modifications to the control strategy
are finally verified by simulations. |
