V s imulation r esults the system of fig 4 has been

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V. S IMULATION R ESULTS The system of Fig. 4 has been simulated using each one of the previously described current control techniques for the active filter. The controllers include the implementation of all the aforementioned refinements, so that the achieved performance is, as realistically as possible, at its best level [5]. Figs. 6 and 7 describe the system’s operation with the digital deadbeat control for and respectively. In particular, the upper part of Fig. 5 shows the relevant system’s waveforms; these are the line voltage the line current the rectifier current the active filter current superimposed to its reference and the current error On the bottom, the corresponding line current spectrum, referred to the amplitude of the fundamental current, is shown. The
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726 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 45, NO. 5, OCTOBER 1998 (a) (b) Fig. 6. (a) Simulated active filter behavior with and deadbeat control; (150 A/div), (75 A/div), (2 ms/div). (b) Line current spectrum. same waveforms and line current spectrum are illustrated by Fig. 6 in the case of To ease the comparison, the same 0-dB reference level as in the case of is taken for the spectrum. It is possible to notice the relevant effect, in terms of current error, of the increase of the current that occurs when the firing angle is set to 40 . The harmonic content of the line currents in the two cases confirms this performance degradation. The quality of the compensation is especially degraded in the high-frequency range of the spec- trum, where the effect of the spikes in the current waveform is particularly evident. It may be remarked that the spikes in the current error waveform are due to the predictive compensation strategy, which is essentially a derivative action on the current reference adopted here [13]. As a consequence, the effect is more evident when the slope of the current reference is steeper. In any case, this predictive compensation reduces the tracking error, due to the intrinsic delay of the deadbeat technique, occurring at the steep current edges. Thus, the resulting error is much lower than that attained without any compensation. Fig. 8 reports the results of the system’s simulation with the linear current controller for As in the previous case, the same waveforms are evaluated also for (a) (b) Fig. 7. (a) Simulated active filter behavior with and deadbeat control; (150 A/div), (75 A/div), (2 ms/div). (b) Line current spectrum. and are shown in Fig. 9. Again, the spectra current references are the same for both cases. As the load power is unchanged, these references practically coincide with those of the deadbeat control. As can be seen, the linear regulator also exhibits a certain performance degradation as increases. For this controller, as stated before, the main limitation is represented by the quite low achievable bandwidth of the linear regulator.
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  • Fall '19
  • Current Source, IEEE Trans, Luigi Malesani

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