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Sliding-Mode Control of Switched-Mode Power Supplies
Published in Timothy L. Skvarenina, The Power Electronics Handbook, 2018
Giorgio Spiazzi, Paolo Mattavelli
A classical control approach relies on the state space averaging method, which derives an equivalent model by circuit-averaging all the system variables in a switching period [3-5]. On the assumptions that the switching frequency is much greater than the natural frequency of system variables, low-frequency dynamics is preserved while high-frequency behavior is lost. From the average model, a suitable small-signal model is then derived by perturbation and linearization around a precise operating point. Finally, the small-signal model is used to derive all the necessary converter transfer functions to design a linear control system by using classical control techniques. The design procedure is well known, but it is generally not easy to account for the wide variation of system parameters, because of the strong dependence of small-signal model parameters on the converter operating point. Multiloop control techniques, such as current-mode control, have greatly improved power converter dynamic behavior, but the control design remains difficult especially for high-order topologies, such as those based on Cuk and SEPIC schemes.
Structure of Bipolar Junction Transistor
Published in Michael Olorunfunmi Kolawole, Electronics, 2020
A large variety of BJT models have been developed in the literature leading to an understanding of the transistor’s behavior and making it easy to describe its frequency dependence. However, one distinguishes between small-signal and large-signal models. The small-signal model lends itself well to small-signal design and analysis. Small-signal models are a linear representation of the nonlinear transistor electrical behavior. They are also a linear approximation to the large-signal behavior. Whereas, the charge control model is particularly well suited to analyze the large-signal transient behavior of a bipolar transistor. These two types are discussed under appropriate subheadings in this section.
PSO Based reduced order modelling of autonomous AC microgrid considering state perturbation
Published in Automatika, 2020
Mudita Juneja, S. K. Nagar, Soumya R. Mohanty
An optimal reduced order model of the autonomous microgrid system is derived using the dominant pole retention and PSO technique. The poles nearest to origin are retained in the reduced order model, and the error between full order and reduced order model is minimized by adopting the PSO algorithm. The 36th order small signal model is reduced to a 9th order approximation with high accuracies in time as well as frequency domain. The comparative analysis of the proposed order reduction method with that of balanced truncation method is also obtained by comparing the impulse, step and ramp responses; and bode plots obtained through both the methods. The eigenvalue analysis identifies the state variables of the original system, whose major influences are preserved in the reduced order model.
A novel hybrid control strategy for SIDO CCM buck converter with reduced cross regulation
Published in International Journal of Electronics Letters, 2019
The current of output capacitor directly reflects the load variation which causes the cross regulation in another output. Thus, the motivation of this letter is to utilise the capacitor current ripple to reduce the cross regulation of SIDO CCM buck converters. A hybrid voltage mode-capacitor current ripple control (VCHC) strategy is proposed for SIDO CCM buck converters to suppress the cross regulation. The frequency-domain analysis based on the developed small-signal model of the proposed converter indicates that the proposed strategy significantly reduced the cross regulation comparing with the converter with traditional voltage mode-inductor current ripple control (VIHC). Moreover, with the proposed control technique, the transient performance of the converter is also improved. Finally, the simulation and experiment results verify the effectiveness of the proposed control strategy.
Inertia Enhancement of an Isolated DC Microgrid Using Hierarchical Virtual Inertia Control
Published in IETE Journal of Research, 2022
Soumya Samanta, Jyoti Prakash Mishra, Binoy Krishna Roy
In order to find out the suitable parametric values of the proposed controller, small signal model of the bidirectional DC–DC converter and its control is established by expressing the variables used in the mathematical expressions as the sum of the steady-state variables and their respective small perturbations. Figure 4 presents the small signal model of the bidirectional DC–DC converter. In general, throughout the small signal modelling, the is considered as the small perturbation of the corresponding state variable x. Ignoring higher order perturbations of the state variables and applying Laplace transform, the small signal model is established and shown in the next subsections.