Study Of Single-phase Power Electronic Load Based On Back To Back Topology

In modern era,stable performance power supplies is an important condition to protect the normal operation of society,in order to ensure power supplies’ performance to meet the industry standards,power supplies need to be a lot of testing before leave the factory.The traditional test method is use resistors,inductors,capacitors,rectifier and other components to make up such as pure resistive load,RL load,RC load and typical nonlinear load these actual conventional loads,use these loads to test the leaving factory power supplies’ performance.This traditional method has many disadvantages,such as high energy consumption and poor flexibility.It falls behind the level of modern technologies.This thesis describes an energy feedback type single-phase power electronic load simulation system,which is based on modern power electronics technology,digital control technology.The topology of the system is back to back type topology with intermediate DC link,the core component of the unit is a single-phase Voltage-type PWM Converter,this power electronic load simulation system can simulate the actual load on flexible single-phase AC power supply factory test,but also can save a lot of energy,correspond with the current era of technological development requirements.Firstly,the thesis analyzes the overall structure of the power electronic load simulation system and how it works,given the system pre-load analog converter for all possible current paths in the unipolar modulation frequency doubling to discuss specific load simulation the command reference current generation method,designed the inductors’ of main circuit AC input and output side,the capacitor’s parameter of intermediate DC side.The thesis then analyzes the current system of single-loop control system pre-load and post-analog converter unit converter unit level energy feed-network voltage and current double closed-loop control system design,simulation purely resistive,inductive and resistive-capacitive resistance which class of linear regulator uses the load on the system before the current closed-loop control system-level calibration;nonlinear loads using analog "proportional + repetition" pre-regulator system to correct the current closed-loop control system,using quasi-resonant controller proportional system dual-stage current inner loop control system to correct;the system after using the regulator level dual-loop control system to correct DC voltage outer loop.The thesis also analyzes the source of the DC bus voltage superimposed harmonic interference voltage feed-forward networks and their impact on current net after-class energy fed converter unit control system how to suppress the influence caused by harmonicinterference voltage;The paper also describes the of the principle and design process of a single-phase system software PLL.Finally,this thesis analyzes the process of building the power electronic load simulation system’s hardware experiment platform,the ideas and methods of how to compile the control program,and the experiment results of the purely resistive load simulation conditions.