五电平变频器仿真模型的建立

变频器在工农业、国防等领域做出巨大贡献的同时,也产生了一些显著的负面效应。PWM变频器在应用中会产生共模电压。共模电压在IGBT的高速开关期间会产生高频充放电电流,这个电流通过电机内部的寄生电容产生流入地线的漏电流。漏电流过大将对电源产生电磁干扰;感应的轴电压过高还会使电机轴承过早损坏,从而影响系统运行的可靠性。提出了一种新的五电平变频器模型,与两电平逆变器和被常规的脉宽调制控制的嵌位电压相比,所提出的五电平变频器可以使产生的共模电压从最大值到最小值之间明显的降低,并且不会使交流驱动电机的控制效果下降。

The Establishment of Five-level Converters Model

Converter makes great contribution to industry and agriculture,but it brings noticeable negative influence at the same time.Pulse width modulated(PWM) converter can generate common-mode voltage.Common-mode voltage can produce charge-discharge current at the distant of every insulated gate bipolar transistor(IGBT) high-speed switching.The current creates ground current escaping to earth through stray capacitors inside motors.The large ground current can create electromagnetic interference to the source and shorten the life of motor bearings by induced high shaft voltage,effect reliability of the whole system.A novel five-level converter model is presented in the text,compared to a two-level converter and NPC converter controlled by conventional PWM,the proposed five-level converter can results in a remarkable reduction in peak-to-peak of common-mode voltage.the proposed PWM strategy can be easily implemented in software without degradation of control performance in ac motor drives.