Abstract
The performance of active disturbance rejection control (ADRC) algorithms can be limited in practice by high-frequency measurement noise. In this article, this problem is addressed by transforming the high-gain extended state observer (ESO), which is the inherent element of ADRC, into a new cascade observer structure. Set of experiments, performed on a dc–dc buck power converter system, show that the new cascade ESO design, compared to the conventional approach, effectively suppresses the detrimental effect of sensor noise overamplification while increasing the estimation/control performance. The proposed design is also analyzed with a low-pass filter at the converter output, which is a common technique for reducing measurement noise in industrial applications.
Highlights
R ENEWABLE energy sources, like fuel and photovoltaic cells, are rapidly evolving technologies for DC voltage generation, which results in proliferation of DC–DC buck converters in power applications
Since the conventional form of active disturbance rejection control (ADRC) uses a highgain observer (HGO) structure to estimate selected signals, its capabilities are intrinsically limited by the presence and severity of high-frequency sensor noise, as discussed in [6]– [8]
Same compromise can be seen in the ADRC works for buck converters in which the measured system output is oftentimes corrupted with highfrequency noise [10]
Summary
R ENEWABLE energy sources, like fuel and photovoltaic cells, are rapidly evolving technologies for DC voltage generation, which results in proliferation of DC–DC buck converters in power applications. Several types of solutions were proposed to solve the problem of attenuating the effects of measurement noise in high-gain observers. They mainly address it by: employing nonlinear [4], [11] or adaptive techniques [12], redesigning the local behavior by combining different types of observers [13], using low-power structures [14]–[16], or modifying standard low-pass filters [17]. Following the general idea shown in [18], we propose a virtual decomposition of the total disturbance present in the DC-DC buck converter system, allowing to design a cascade structure of ESO, where each level of the observer cascade is responsible for handling a particular type and frequency range of estimated signal. The expression ls∞ ∶= lim supt→∞ is used for the sake of notation compactness
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