中文摘要：

针对非隔离型三相三电平光伏逆变器的中点平衡及共模电压问题，提出一种具有低共模电压的三电平逆变器中点平衡算法，即在十三矢量调制策略基础上添加共模电压小的小矢量对中点电位进行控制，并根据此思想进一步提出一种基于零序电压注入的载波实现方法，该方法不需进行扇区判断和复杂的几何运算，因算法简单易于工程实现。实验结果证明本调制策略在降低共模电压的同时可实现中点平衡控制。

英文摘要：

In order to solve the neutral point voltage balance and common-mode voltage problem of three-level transform less photovoltaic inverter, a new modulation strategy to balance the neutral point voltage for three-level inverters with low common-mode voltage is proposed, which uses small space vector with low common-mode voltage to control neutral point voltage based on thirteen vectors modulation strategy. According to this thought, a carrier implementation method based on the zero-sequence voltage injection is proposed in this paper. This method does not need sector judgment and complex geometry processing, it is simple and easy to implement in project. Experiment results showed that the neutral point potential is balanced with low common-mode voltage.