Xiao-Ping Yang

Bio: Xiao-Ping Yang is an academic researcher from Xi'an Jiaotong University. The author has contributed to research in topics: Buck converter & Hopf bifurcation. The author has an hindex of 3, co-authored 4 publications receiving 49 citations.

Analysis of limit cycle behavior in DC–DC boost converters

Abstract: This paper deals with limit cycle behaviors in DC–DC boost converters with a proportional-integral (PI) voltage compensator, which is a popular design solution for increasing output voltage in power electronics. Extensive cycle-by-cycle numerical simulations are used to capture all limit cycle behaviors. It is found that there exist two types of limit cycle behaviors rather than only one type in a boost converter. For each type of limit cycle, its underlying mechanism is revealed by circuit analysis. Moreover, the critical condition is derived to predict the occurrence of the limit cycle behaviors in terms of Routh stability criterion, and the analytical expressions for the limit cycles I and II are given based on the averaged model approach. Finally, these theoretical results are verified by numerical simulations and circuit experiments.

Method for judging stability of distributed power-supply system based on equivalent open-loop transfer function

Abstract: The invention discloses a method for judging the stability of a distributed power-supply system based on an equivalent open-loop transfer function. The method comprises the following steps: firstly, equivalently transforming a noise sensitivity transfer function of the system, on the basis of an equivalent two-port network characteristic of a source switch power supply, and deducing the equivalent open-loop transfer function shown in the description; and then respectively measuring port voltages v1(s) and v2(s) by connecting a small signal current source delta (s) to a connection bus of a converter, acquiring the equivalent open-loop transfer function shown in the description under the small signal disturbance, and drawing a Gop(s) nyquist diagram; and lastly, judging the stability of the system and forecasting the stability margin of the system according to the nyquist diagram. By using the method provided by the invention, the restraining terms of the original impedance ratio standard are extended. Besides, the method provided by the invention is easily realized and has important theoretic sense and application value in analyzing and designing the distributed power-supply system.

A Review on Stability Analysis Methods for Switching Mode Power Converters

Abstract: In distributed power generation systems a pivotal role is played by DC-DC power converters that are employed to connect local loads to local power sources. These converters are used either in combinations of series/parallel connections or as stand-alone devices. A lot of work has taken place in the stability analysis of these converters and several methods have been used/proposed with different properties, strengths and weaknesses. Describing all existing methods is probably a never ending task and therefore in this tutorial paper four different methods will be presented by pointing out their main properties and explaining briefly how they can be used in applications that involve power converters. More specifically, the chosen methods are based on 1) the Poincare map, 2) Saltation matrix, 3) trajectory sensitivity, and 4) steady-state-response analysis of the discrete-time model. Simple case studies from previous publications are collected and presented in order to further explain these methodologies. Finally, this paper intents to describe some of the future challenges that exist in the area of stability analysis of power converters especially when these are employed in distributed generation applications.

Synthesis of Canonical Elements for Power Processing in DC Distribution Systems Using Cascaded Converters and Sliding-Mode Control

Abstract: Switched power converters are used to interface the dc output in modern distributed power generation systems, which are usually aggregated to the main grid to yield the necessary power using interconnected modules. Synthesis, modeling, and stability analysis of interconnected systems using cascaded converters working under sliding-mode control are considered in this paper. A systematic procedure to synthesize cascaded connection of dc-dc boost converters is introduced. The approach is based on making each module to behave as a suitable canonical element for power processing. Three different elements are considered, which are the dc power gyrator, the dc transformer, and the dc loss-free resistor. These canonical elements are designed by means of a sliding-mode control theory and then their dynamic behavior is studied in detail. The sliding-mode conditions for each case are derived in closed form to obtain design-oriented criteria for selecting the parameters of the system. The aforementioned canonical elements are compared to select the most suitable one for a distributed power system. Simulation results ensure the correctness of the proposed approach. Experimental measurements corroborate the theoretical predictions and the numerical simulations.