本文最后搭建了一个基于多电平矢量发生的逆变实验系统，制作了一台用矢量发生器驱动的1.5 KW的多电平变换器实验样机，在样机上得到了较为理想的波形。
An experiment prototype of 1.5kw three-level inverter has been manufactured, which is driven by "based on FPGA vector generator". We finally got ideal wave in this experiment system.
利用矢量代数的方法，推导出以方向余弦为参量的物坐标系到世界坐标系的坐标变换矩阵；利用矩阵求逆的方法，推导出世界坐标系到物坐标系的坐标变换矩阵。
The coordinate transformation matrix based on the direction cosine parameters from the object coordinate system to the world coordinate system is derived by vector algebra.
通过把高阶张量写成若干逆变和协变矢量的乘积，直接从变换入手，给出了定义高阶张量协变导数的另一种方法。
This paper discusses another way, which is rewritten as product of a few contravariant vectors and covariant vectors, to define higher order tensors covariant derivative through transformations.
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