Gong Chun-ying

Modeling and analysis of a buck/boost bidirectional converter with developed PWM switch model

The aim of this paper is to provide a general method for bidirectional converter simulation and evaluation. A developed PWM switch model is proposed for bidirectional power flow application. A typical buck/boost bidirectional converter is chosen as a test bench for evaluation. Small signal analysis results show mode transition between battery charging and discharging modes. It provides a fast simulation tool to investigate steady and transient response of converters. The accuracy of the modeling technique is verified by a detailed comparison of simulated results with the developed PWM switch model and component circuit.

Modeling and Analysis of Hysteretic Current Mode Control Inverter

In this paper, a small signal model of hysteretic current mode control with variable frequency and fixed hysteretic band is presented, based on three terminal averaged switch cell of buck converter in continuous current mode. This model reveals that the averaged current is the control target of hysteretic control. And phase lag of current loop with high switching frequency is quite small that makes current loop equivalent power stage be a proportional component. The conclusion is also valid in large signal analysis. Then an averaged linear model of single phase inverter is derived. The order of the system closed loop characteristic equation is reduced due to hysteretic current control introduced. And compensation principles of a single phase inverter are investigated with Routh criterion, which is easy to implement in practice and a good comprise between stability and stable/dynamic performance could be achieved.

A novel dual Boost/dual Buck AC/AC converter

A novel dual Boost/dual Buck AC-AC converter which is very suitable for the variable-frequency power system of airplane (360Hz–800Hz) is proposed in this paper. It is constructed by directly connection of a dual Boost rectifier and a dual Buck inverter which inherit the merits of high reliability and efficiency of them for no hidden danger of shoot-through and no freewheeling current flows through the body diodes of power switches. The operational principle and control method are briefly talked about first; then the method of designing inductors is deduced, also the principle of choosing DC bus voltage and capacitors are proposed. At last, a 1KW laboratory prototype is designed. Both experimental and simulation results verified the validity of the presented circuit.

Small signal modeling and analysis of synchronverters

Synchronverters are inverters that mimic the synchronous generators. The synchronverter can be easily operated in both island mode and on-grid mode, which is very suitable for the Micro-grid. A new method to get the small signal model of the synchronverter is proposed in this paper. The decoupling of the active power and reactive power of the synchronverter will also be discussed. The mathematic model of synchronverters are briefly talked about first; then the small signal modeling of synchronverters, also the method of choosing the suitable operational parameters of synchronverters are proposed. At last, a 5kW+5kvar laboratory prototype is designed to prove the validity of the small signal model. Simulation and experimental results verified the validity of the presented method.

Detailed design of high-frequency planar power transformer

As the operating frequency has been increased toward the megahertz range to improve the power density, the accurate losses and temperature rise estimation of power transformer becomes very important in the power converter design stage. Calculated core losses, dielectric losses, winding ac-resistance, inductance equations are figured out in this paper. The parameter design of the planar transformer is verified by the Finite Element Method (FEM) Simulations and could be utilized to optimize the transformer design procedure. Furthermore, Ansys Computational Fluid Dynamics CFD simulation helps predict the temperature rise of transformer.