DC/AC Modeling And Real-time Simulation Technology Based On FPGA

The research and development of hardware in the loop real-time simulation technology and platform for power electronics can facilitate the experiment and teaching of power electronics technology.Compared with the general software simulation,realtime simulation can test all kinds of functions,fault conditions and extreme environment of power electronic system,which is helpful to accelerate the development of products.Compared with the conventional processor,FPGA(field programmable gate array)has good parallel processing ability and high clock frequency,which is suitable for fast computing of power electronic system,and has become the first choice for real-time simulation of power electronic system.Therefore,this dissertation uses FPGA + PC joint real-time simulation platform for experiments.For real-time simulation,the modeling method and mathematical algorithm of power electronic system are important factors affecting the simulation performance,so it is necessary to study the real-time simulation modeling method.Moreover,the real-time simulator based on constant step size sampling operation has the phenomenon of sampling distortion when processing high-frequency PWM signals.In order to solve the above problems,this dissertation mainly completes the following work.(1)The basic structure and mathematical model of HIL real-time simulation system for DC / AC inverter are analyzed in detail.The state space method and binary LC method are used to model the HIL real-time simulation system.Aiming at the problem of switching oscillation in binary LC modeling method,an improved binary LC method is used to improve the accuracy of the model and reduce the switching oscillation.The correctness of the modeling method is verified by off-line simulation.Finally,the characteristics of binary LC method and state space method are compared in detail,and their applications are analyzed.(2)A method of changing the switching function based on the principle of area equivalence is proposed.This dissertation first introduces the sampling error of fixed step simulation when processing high frequency PWM signal,and then combines small step length integration with large step length circuit operation by using the characteristics of FPGA which can realize multi time domain synchronous calculation.Finally,a threephase inverter based on LC filter is taken as an example to verify the effectiveness of the proposed method.(3)The FPGA development process of power electronics model is studied.In view of the complex hardware circuit flow design and tedious code writing,this dissertation uses the System Gnerator development tool to realize the automatic generation of system model to code.(4)A prototype of real-time simulation platform based on FPGA + PC is developed,which is based on state space method and improved binary LC modeling method respectively.The real-time simulation experiment of three-phase DC/AC inverter is carried out on the platform,and the correctness of platform design,modeling method and proposed high-frequency PWM signal processing method is verified.