Augmented Buck Converter Design Using Resonant Circuits for Fast Transient Recovery

High-performance buck converters are often required in modern power electronic applications. An augmented buck converter (a main buck converter with augmentation circuits) can achieve fast transient recovery and small output voltage deviation. Compared with other augmentation circuits, a resonant augmentation circuit offers potential electromagnetic interference reduction due to the relatively low didt value and compacts the circuit through a reduced inductance for resonance. In this paper, the performance analysis of an augmented buck converter constructed with the resonant circuit are described in detail in terms of voltage-deviation band and power loss. A circuit design and control principle is also proposed for achieving the required voltage deviation for a given transient-detection delay. A 12-to-5-V converter prototype is built to verify the analysis and effectiveness of the proposed methodology. It is demonstrated that the voltage deviation is reduced from 360 to 200 mV using the proposed resonant augmentation circuits and control scheme. The efficiency study shows that the power loss varies from 0.02 to 0.72 W, when the repetition frequency of 5-to-10-A transients changes from 100 to 5 kHz.Department of Electronic and Information Engineerin

Resonant augmentation circuits for a buck converter achieving minimum-time voltage recovery from load transients

6th Annual IEEE Energy Conversion Congress and Exhibition, ECCE 2014, 14-18 September 2014This paper presents the use of a resonant circuit for fast voltage recovery of power supplies under large-signal load transients. Previous works have shown that an augmentation circuit (or auxiliary circuit) for voltage recovery may be used to improve the dynamic response, while the main converter is operating for current recovery with load current feedforward control. A compact, low cost and magnetic-coreless topology with a simple control algorithm to achieve an augmentation circuit is presented. In the prototype, the inductors are realized using printed copper wires. The control algorithm is realized by a low cost and low density logic device. Simulation and experimental results validate the feasibility and effectiveness of the circuit.Department of Electronic and Information Engineerin

Modeling Guidelines and a Benchmark for Power System Simulation Studies of Three-Phase Single-Stage Photovoltaic Systems

This paper presents modeling guidelines and a benchmark system for power system simulation studies of grid-connected, three-phase, single-stage Photovoltaic (PV) systems that employ a voltage-sourced converter (VSC) as the power processor. The objective of this work is to introduce the main components, operation/protection modes, and control layers/schemes of medium- and high-power PV systems, to assist power engineers in developing circuit-based simulation models for impact assessment studies, analysis, and identification of potential issues with respect to the grid integration of PV systems. Parameter selection, control tuning, and design guidelines are also briefly discussed. The usefulness of the benchmark system is demonstrated through a fairly comprehensive set of test cases, conducted in the PSCAD/EMTDC software environment. However, the models and techniques presented in this paper are independent of any specific circuit simulation software package. Also, they may not fully conform to the methods exercised by all manufacturers, due to the proprietary nature of the industry

Dynamic average-value modeling of direct power-controlled active front-end rectifiers

Active front-end (AFE) rectifiers are becoming widely used in medium-to-high-power adjustable speed drives (ASDs) to achieve regenerative operation and meet the energy efficiency and harmonic requirements. The typical control methods used with AFE rectifiers include voltage-oriented control (VOC), direct power control (DPC) and virtual-flux-based methods. This paper presents a dynamic average-value model (AVM) of the AFE rectifier system which is based on the voltage-sou