Small-signal models of DC-DC converters are often based on a state-space averaging approach, from which both control-oriented and other frequency-domain characteristics, such as input or output impedance, can be derived. Updating these models when extending the converter by filters or non-trivial loads, or adding control loops, can become a tedious task, however. To simplify this potentially error-prone process, a modular modeling approach is being proposed in this article. It consists of small state-space models for certain building blocks of a converter system on the one hand, and standardized operations for connecting these subsystem models to an overall converter system model on the other hand. The resulting state-space system model builds upon a two-port converter description and allows the extraction of control-oriented and impedance characteristics at any modeling stage, be it open loop or closed loop, single converter or series connections of converters. The ease of creating more complex models enabled by the proposed approach is also demonstrated with examples comprising multiple control loops or cascaded converters.
Switched-capacitor (SC) DC-DC voltage converters are widely used in power delivery and management of modern integrated circuits. Connected to a common supply voltage, SC converters exhibit cross-regulation/coupling effects among loads connected to different SC converter stages due to the shared components such as switches, capacitors, and parasitic elements. The coupling effects between SC converter stages can potentially be used in covert communication, where two or more entities (e.g., loads) illegitimately establish a communication channel to exchange malicious information stealthily. To qu…
This paper presents a Direct Mapped Method (DMM) for real-time simulation of high switching frequency resonant converters. The DMM links state variables to diode statuses and provides an exact and noniterative solution to network equations. The proposed method is implemented on FPGA to simulate an LLC converter with switching frequencies ranging up to 500 kHz. The best reported implementations of DMM achieve a 25 ns simulation time-step for a wide range of clock frequencies, ranging from 40 MHz to 320 MHz.
A significant amount of converter-based generation is being integrated into the bulk electric power grid to fulfill the future electric demand through renewable energy sources, such as wind and photovoltaic. The dynamics of converter systems in the overall stability of the power system can no longer be neglected as in the past. Numerous efforts have been made in the literature to derive detailed dynamic models, but using detailed models becomes complicated and computationally prohibitive in large system level studies. In this paper, we use a data-driven, black-box approach to model the dynamic…
In this paper, authors want to comment on a recently published article describing the Mathematical Modeling of Current Source Matrix Converter (CSMC) with two modulation strategies, namely: Venturini and Space Vector Modulation (SVM). Reported flaws are broadly classified into two (2) categories; namely: (1) Technical Flaws and (2) Rubric and Grammar Flaws. This paper not only reports these flaws but also provides suggestive rectifications for correction and improvement of the published article.
The paper establishes a methodology to overcome the difficulty of dynamic frame alignment and system separation in impedance modeling of ac grids, and thereby enables impedance-based whole-system modeling of generator-converter composite power systems. The methodology is based on a frame-dynamics-embedding transformation via an intermediary steady frame between local and global frames, which yields a locally defined impedance model for each generator or converter that does not rely on a global frame but retains all frame dynamics. The individual impedance model can then be readily combined int…
In this manuscript, the performance of an ultracapacitor fuel cell in grid connected mode is investigated. Voltage regulation to the ultracapacitor was achieved with a three level bidirectional DC-DC converter while also achieving power flow from the grid to the ultra-capacitor via the bidirectional converter. The choice of a bidirectional three level converter for voltage regulation is based on its inherently high efficiency, low harmonic profile and compact size. Using the model equations of the converter and grid connected inverter derived using the switching function approach, the grid's d…
This article details a complete procedure to derive a data-driven small-signal-based model useful to perform converter-based power system related studies. To compute the model, Decision Tree (DT) regression, both using single DT and ensemble DT, and Spline regression have been employed and their performances have been compared, in terms of accuracy, training and computing time. The methodology includes a comprehensive step-by-step procedure to develop the model: data generation by conventional simulation and mathematical models, databases (DBs) arrangement, regression training and testing, rea…
This article presents the characterization of analog and digital control loops using PID and PIDN control algorithms for bidirectional buck and boost converter (BBC). Control loops of BBC are designed and implemented in MATLAB code using transfer functions in time domain with unit step response and in frequency domain with bode plots and pole-zero plots. These transfer functions are obtained by average large signal modeling of BBC. Actions of analog and digital control loops are characterized in order to ensure stability and dynamic response of BBC which is a bottleneck in renewable energy app…
Artificial Intelligence for Power-Converter-Rich Electrical Systems: A Review
University of Cambridge（剑桥大学）；Shanghai Jiao Tong University（上海交通大学）；University of Leicester（莱斯特大学）；Shanghai University of Electric Power（上海电力大学）；National Tsing Hua University（国立清华大学）；Nanyang Technological University（南洋理工大学）
Enabling Small-Signal Stability Analysis of Black-Box Voltage Source Converters in Large-Scale Modern Power Systems
Universitat Politècnica de Catalunya（加泰罗尼亚理工大学）；Centre d’Innovació Tecnològica en Convertidors Estàtics i Accionaments（静态转换器与驱动技术创新中心）；Red Eléctrica - Redeia（西班牙国家电网）
Linear Time Periodic (LTP) framework-based analysis of Voltage Source Converters (VSCs) is becoming popular, a driven factor is that many of the existing VSC applications inevitably exhibit the periodic steady-state (PSS), e.g., VSCs with unbalanced grid connections and the operation of a modular multilevel converter (MMC). In these studies, acquisition of the VSC's PSS conditions is a necessary precondition for proper linearization and stability analysis, and the efficiency of this process is particularly important for parametric studies. To this end, this work develops a computational method…
Continuously Variable Series Reactor (CVSR) can adjust the total reactance in an ac circuit using the saturation characteristic of the ferromagnetic core, shared by an ac and a dc winding. The bias magnetic flux produced by the dc winding can regulate the equivalent ac inductance in order to control power flow, damp oscillations, or limit fault currents. Gyrator-Capacitor approach is used to model the interface between the magnetic and the electric circuits. Two different dc control source models are considered: the usual ideal dc source and a realistic dc source composed of a power electronic…
Current-mode control is one of the most popular controller strategies for power converters. With the advent of wide bandgap devices including GaN and SiC, higher switching frequencies have become more viable at higher power because of lower switching losses. However, the advantage of higher switching frequency for faster, higher bandwidth control is squandered because of current sensor interference. We present a framework for characterizing and analyzing this interference as uncertainties to the controller model. These uncertainties introduce additional dynamics and nonlinearity that can resul…
