基于空间矢量嵌入的优化载波移相控制方法

Optimized Carrier Phase-shift Control Method Based on Space Vector Embedding

随着分布式能源的不断发展,直流级联变换器被广泛应用于分布式能源接入中高压直流电网的场景中。然而,分布式能源的随机性使得各子模块的功率无法保持一致,进而导致各功率单元输出的电压矢量幅值不同。此时,传统的载波移相调制策略将无法消除开关频率处的电压/电流谐波分量,导致滤波器体积增大。针对直流级联变换器在开关频率处的谐波抑制问题,从几何图论的角度提出了一种基于空间矢量嵌入的优化载波移相控制方法。所提方法使用相量图来获得具有任意数量子模块单元的直流级联系统中的各子模块的优化载波移相角,不仅计算过程简单清晰,且无需要复杂的数学迭代搜索算法。最后,通过3个模块单元的直流级联系统实验平台验证了该方法的有效性。

With the constant development of distributed energy,DC cascaded converter is widely used in the scenario of distributed energy connected to medium and high voltage DC power grid.However,the power of each submodule can not be consistent due to the randomness of distributed energy,resulting in different amplitude of voltage vectors output by each power module.At this time,the traditional carrier phase-shift modulation strategy can not eliminate the voltage/current harmonic component at the switching frequency,resulting in the increase of the filter volume.Aiming at the harmonic suppression of DC cascaded converter at switching frequency,an optimized carrier phase-shift control method based on space vector embedding is proposed from the perspective of geometric graph theory.The proposed method uses the phasor diagram to obtain the optimized carrier phase-shift angle of each submodule in the DC cascaded system with any number of submodule units.The calculation process is simple and clear,and there is no need for complex mathematical iterative search algorithm.Finally,the effectiveness of the method is verified by a DC cascaded system experimental platform with three module units.