非正交三维坐标系下多电平空间矢量调制策略

脉冲宽度调制是三相四线制多电平变流器控制的难点,脉冲宽度调制策略将直接影响零序分量输出控制的优劣,传统三维空间矢量调制策略在电压零序分量控制和算法复杂度两个方面很难取得良好的平衡。提出一种非正交三维坐标系下的空间矢量调制策略。该方法通过建立一种三维非正交坐标系,将传统正交三维空间坐标系下的三角函数运算简化为简单的代数运算,在降低三维空间矢量调制算法复杂性的同时保留对于零序分量的独立控制。另外,针对多电平变流器固有中点电位不平衡问题提出一种简单的控制策略。仿真分析和实验结果验证了所提出的非正交三维坐标系下的调制策略的正确性及有效性。

Multi-Level Space Vector Modulation Strategy in a Non-Orthogonal Three-Dimensional Coordinate System

Pulse width modulations is a key technology in three-phase four-wire multi-level converter controlling. It directly affects the controlling performance of output zero-sequence voltage component. Traditional three-dimensional space vector modulation strategies have difficulties in achieving a good balance between voltage zero-sequence component controlling and algorithm complexity. A novel space vector modulation strategy in non-orthogonal three-dimensional coordinate system is proposed in this paper. Under this new non-orthogonal three-dimensional coordinate system, the proposed modulation has converted the original trigonometric functions in orthogonal three- dimensional space coordinate into simple algebraic operations, which greatly reduces algorithm complexity of the three-dimensional space vector modulation while preserving the independent control on the zero-sequence component. The experimental results verify the correctness and effectiveness of the proposed three-dimensional space vector modulation.