基于FFT的三电平逆变器的死区补偿策略

Dead-time Compensation Strategy of Three Level Inverter Based on FFT

针对死区所带来的三电平逆变器输出电压和输出电流的畸变,通过分析死区效应的机理,对死区时间、功率器件的电压降、开通和关断时间如何影响三电平逆变器的输出电压进行了详细地论述,据此提出了一种基于快速傅里叶变换(FFT)的三电平逆变器的死区补偿策略,该策略利用FFT对电流进行滤波以准确判断电流的极性,进而补偿死区。最后,基于三电平逆变器进行仿真验证,结果表明,所提出的采用FFT的死区补偿策略能够有效减小死区效应造成的电流畸变,改善零电流钳位现象。

The mechanism of the dead-time effect was analyzed firstly.Then,considering the influence on the output voltage and current of the three-level inverter by dead time,voltage drop,opening time,turn-off time of power devices and grid voltage,a mathematical model of three level inverter was built,and a dead-time compensation strategy for three level inverter based on fast fourier transformati(FFT)was proposed.The FFT was used to filter current to determine the polarity of current accurately in the strategy.The simulation and experimental results based on three-level inverter show that the compensation strategy of the dead time can effectively reduce the harmonic content of the output current introduced by the dead time and avoid the zero-current clamping.