基于电流矢量的三电平逆变器死区补偿策略

DEAD-TIME COMPENSATION STRATEGY BASED ON CURRENT VECTOR FOR THREE-LEVEL INVERTER

为避免直流侧电容的直通,需在功率器件驱动信号上载入必要的死区时间,但随之导致电压电流的畸变。针对上述问题,对三电平逆变器的死区效应展开理论分析,提出一种基于电流矢量的三电平逆变器死区补偿策略。通过分析三电平逆变器的开关切换序列和换向过程,得出在不同电流极性情况下的误差电压矢量。为解决传统策略需检测电流的弊端,研究根据电流幅值自适应设置死区时间,由此补偿矢量可转换为d-q坐标系下的直流分量,跟随电流矢量进行同步旋转。该策略可避免因各种扰动导致的电流过零时的误补偿,并有效改善电流波形。最后,通过基于TMS320F28335控制器的三电平逆变器实验样机,验证所提控制策略的正确性和有效性。

The necessary dead-time is added into driving signal of power device to avoid the direct-through of the DCside capacitors,but this results in distortion of the voltage and current. Aiming at above problem,the dead-time effect ofthree-level inverter is theoretically analyzed,and a dead-time compensation strategy based on current vector for threelevel inverter is proposed. By analyzing the switching sequence and commutation process of the three-level inverter,theerror voltage vector under different current polarity conditions is obtained. In order to solve the disadvantage of thetraditional strategy to detect current,study adaptively setting dead time based on the current amplitude,therefore,thecompensation vector can be converted into a direct current component in the d-q coordinate system and synchronouslyrotated following the current vector. This strategy can avoid erroneous compensation when the current is zero due tovarious disturbances,and effectively improve the current waveform. Finally,through the prototype of the three-levelinverter based on TMS320 F28335 controller,the correctness and effectiveness of the proposed control strategy areverified.