Feed forward (control)

Summary

A feed forward (sometimes written feedforward) is an element or pathway within a control system that passes a controlling signal from a source in its external environment to a load elsewhere in its external environment. This is often a command signal from an external operator. A control system which has only feed-forward behavior responds to its control signal in a pre-defined way without responding to the way the load reacts; it is in contrast with a system that also has feedback, which adjusts the input to take account of how it affects the load, and how the load itself may vary unpredictably; the load is considered to belong to the external environment of the system. In a feed-forward system, the control variable adjustment is not error-based. Instead it is based on knowledge about the process in the form of a mathematical model of the process and knowledge about, or measurements of, the process disturbances. Some prerequisites are needed for control scheme to be reliable by pu

Official source

https://en.wikipedia.org/wiki/Feed_forward_(control)

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DC-DC Converter based on the Asymmetric Multistage Stacked Boost Architecture with Feed-Forward Control for Photovoltaic Plants

Georgios Mademlis, Alfred Rufer, Gina Kristin Steinke

A new feed-forward control technique for a DC-DC step-up converter based on the asymmet-ric Multistage Stacked Boost Architecture (MSBA) is presented in this paper. The proposed closed loop control scheme can provide improved accuracy in the steady-state operation and high dynamic performance. The asymmetric MSBA converter is a single output high-voltage DC-DC step-up converter that comprises several in-series connected capacitors with active voltage balancing circuits. The converter can attain high voltage ratios and thus, it is a suita-ble solution for the high voltage transmission requirements of the large photovoltaic (PV) plants. Selective simulation and experimental results are presented in order to validate the effectiveness and the operational improvements of the proposed control system.

2016

Feed-Forward based Control in a DC-DC Converter of Asymmetric Multistage Stacked Boost Architecture

Georgios Mademlis, Alfred Rufer, Gina Kristin Steinke

A new feed-forward control technique for a DC-DC step-up converter based on the asymmetric Multistage Stacked Boost Architecture (MSBA) is proposed. The devel-oped feed-forward controller directly handles the load current and the perturbations that may be caused by the dynamic operation of the converter. Thus, there is no time delay for estimating the error in a control process and therefore, both robust steady-state operation and high dynamic performance can be achieved. The asymmetric MSBA DC-DC converter is a single output high-voltage topology that embodies several in-series active voltage balancing circuits. Thus, there is a need for an improved balancing control method. This can be ac-complished by replacing the conventional Proportional-Integral (PI) controllers with feed-forward type and therefore improved balancing between the stages can be attained, be-cause the steady state errors are suppressed and the dynamic response can be enhanced. A thorough theoretical analysis is conducted for verifying the stability of the suggested feed-forward control technique in an asymmetric MSBA converter and selective simulation and experimental results are demon-strated in order to validate the effectiveness and feasibility of the proposed control scheme.

Ieee-Inst Electrical Electronics Engineers Inc2017

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Sound absorption at low frequencies still remains a challenge in both scientific research and engineering practice. Natural porous materials are ineffective in this frequency range, as well as acoustic resonators which present too narrow bandwidth of absorption, thus requiring alternative solutions based on active absorption techniques. In the present work, we propose an active control framework applied on a closed-box loudspeaker to enable the adjustment of the acoustic impedance at the loudspeaker diaphragm. More specifically, based on the proportionality between the pressure inside the enclosure and the axial displacement of the loudspeaker diaphragm at low frequencies, we demonstrate both analytically and experimentally that a PID-like feedback control approach allows tuning independently the compliance, the resistance and the moving mass of the closed-box loudspeaker to implement a prescribed impedance of a single-degree-of-freedom resonator. By considering different control combinations to tailor the resonator characteristics, a perfect absorption (with absorption coefficient equal to 1) is achievable at the target resonance frequency, while enlarging the effective absorption bandwidth. Moreover, the proposed feedback control strategy shows an excellent control accuracy, especially compared to the feedforward-based control formerly reported in the literature. The mismatches between the performance of experimental prototype and the model, likely to result from the control time delay and the inaccuracy in estimating the loudspeaker parameters, can be compensated directly by tuning the control parameters in the control platform. The active resonators implemented through the reported control scheme can be used to build more complex acoustic devices/structures to enable high-efficiency broadband sound absorption or other types of acoustic phenomena such as wavefront shaping.

2022