中文说明：
提出了一种合理的载波相位调制优化方法。该方法结合了子模块的平衡控制，不仅显示了更好的电容电压平衡效果，而且还输出了信号。谐波含量较低。
English Description：
A reasonable carrier phase modulation optimization method is proposed. This method combines the balance control of sub module, not only shows better capacitor voltage balance effect, but also outputs signal. The harmonic content is low.