数字锁相环提高锁相稳定性的方法

A Method to Improve the Stability of Digital Phase-locked Loop

文中针对光伏并网发电系统中数字锁相环易受到过零检测电路影响，其稳定度差的问题，采用了相应的硬件和软件方法解决锁相环稳定性问题。硬件上通过提前过零检测来补偿加重滤波器带来的相位滞后；软件上加入判断过零点真伪的功能，以及先检测过零点再切换后级逆变桥的方法，有效地避免了错误过零点造成的锁相失败问题，取得了很好的效果。

Since zero-crossing detection has negative impact on the stability of digital phase-locked loops （DPLL） in grid-connected photovoltaic system, we utilize a corresponding hardware and software method to solve this problem. As for hardware, we bring forward the zerocrossing detection in order to compensate for the phase lag caused by the filter. In software, we add a function to judge the zero-crossing point and detect the zero-crossing point before the post-inverter, which effectively avoid the failure of phase lock cased by the wrong judgment of zero-crossing point.