中文摘要：

主要研究了采用中点箝位型（NPC）三电平逆变器供电的永磁同步电动机（PMSM）伺服系统；电动机采用转子磁场定向的矢量控制。为了达到控制目的，在三电平逆变器SVPWM调制算法的基础上，引入了零序电压注入法和电容电压前馈法。这种方法较好地控制了中点电位的偏移，以期降低逆变器输出电压谐波含量，改善电动机定子电流波形，这将减小电动机转矩脉动，改善电动机控制性能。

英文摘要：

The permanent magnet synchronous motor（PMSM） servo system fed by neutral point clamped（ NPC ） threelevel inverter was mainly studied with rotor magnetic field oriented vector control. In order to achieve the control purpose, the methods of injecting zero-sequence voltage and capacitance-voltage feed-forward which base on SVPWM algorithm of the three-level inverter were come up with. These methods could control the offset of the neutral point （NP） voltage so well, in order to reduce the harmonic contents of the inverter output voltage, to improve the stator current waveform, which will decrease the motor torque ripple and improve the performance of motor control.