一种新的基于DSP的高精度UPS锁相技术

A novel high precision phase-locked method for UPS based on DSP

本文结合锁相环的原理针对全数字化控制的UPS系统,研究了利用DSP TMS320F240实现高精度锁相的数字锁相环的原理与实现方法。所给出的锁相方法中利用DSP的捕获中断和周期中断读取市电和逆变输出的相差,经PI调节器输出一个载波周期的补偿量,通过动态改变载波周期值实现逆变输出对市电的动态跟踪,理论上相差分辨率可高达0.72°。文中给出了硬件实现电路及程序流程图,建立了z域的线性化模型。为验证本锁相方法,研制了一台220V/50Hz/1.4KW的样机。仿真和实验结果验证了该方案的可行性。

In this paper, the principle and realization method of DPLL （Digital Phase-Locked Loop） with high precision by DSP TMS320F240 is presented. The phase error between UPS and electrical network is sensed by Schmitt Trigger relative to AC power supply and recorded by CAP interrupt and period interrupt of DSP. A Digital PI controller is applied to supply a compensation value for every carrier period. The control strategy and the flow chart of the program are given. The dynamic tracing of inverter output to electrical network is realized by dynamic changing carrier period. The theoretical resolution of phase error is 0.72 degree. A linear model in z domain is built. Simulation result shows that phase-lock is completed within only 0.06s. The dynamic performance is good. A prototype with 50Hz/220V/1.4KW is made to verify the method of DPLL. Experimental results prove the scheme is feasible.