一种单相锁相环的数字实现

摘要

The fundamental principle and performance of phase-locked loop for single-phase grid-connected system was analyzed. The method of constructing voltage vectors,in the a.j? Stationary reference based on second order generalized integrator (SOGI) was proposed. According to the principle of the digital phase-locked loop (DPLL) by means of the transformation from a,/? Stationary reference to d,q synchronously rotating reference for a three-phase system,a DPLL on the basis of a fictitious two-phase transformation for single-phase grid-connected conversion system was implemented. In order to restrain the influence of the grid frequency changes and improve the frequency range of DPLL operating. The synchronously sampling technique is used. Taking several line disturbances such as phase angle jump,frequency step,and harmonics content into consideration,the proposed method is simulated in Matlab software. Real time experiments based on a TMS32OF28O15 DSP platform are conducted for the proposed DPLL. Simulation experiment verify that phase lock loop system can measure the instantaneous frequency and phase of power system.%分析了单相并网系统锁相环的基本原理和特性.介绍了一种基于二阶广义积分器构造α,β静止坐标系下的电压矢量方法.参照三相并网系统基于α,β静止坐标系到d,q同步旋转坐标系的数字锁相环原理,实现了基于虚拟两相直角坐标系的数字锁相环控制.采用同步采样技术抑制电网频率波动对该方法的影响,提高数字锁相环工作的频率范围.利用Matlab软件对电网电压频率、相位角的突变、谐波注入等参数变化的影响做了仿真研究.在此基础上,搭建了以TMS320F28015 DSP为控制核心的实验装置,仿真实验结果表明,该锁相环可以很好地跟踪系统频率的变化从而实现相位的锁定.