三电平双模块并联协同特定谐波消除脉宽调制

Collaborative selective harmonic elimination pulse width modulation for dual-module parallel-connected three-level converters

针对中压大功率并网变流器开关频率低、并网电流谐波大等问题,提出适于中性点钳位型(NPC)三电平双模块并联网侧变流器特定谐波消除脉宽调制(SHEPWM)分频段协同控制策略.通过在低频段控制双模块各自输出谐波为零,在高频段控制并网双模块输出总的谐波为零,有效地提高双模块并联系统电流谐波性能.为了抑制器件死区引起的并网电流中5次、7次谐波,引入频率自适应广义积分控制器.该控制器在离散域直接设计参数,避免数字化过程导致控制器性能偏差.仿真和实验结果验证了所提控制策略的有效性、优越性.

A frequency-dividing collaborative control strategy of selective harmonic elimination pulse width modulation(SHEPWM) for three-level neutral point clamped based dual-module grid-tied converters was proposed aiming at the disadvantages of low switching frequency and large current harmonics of medium voltage high power grid-connected converters. Current harmonic performance of dual-module parallel-connected system was effectively improved by restricting output harmonics of each module to zero in low-frequency band, while total output harmonics of the dual-module was controlled to zero in high-frequency band. A frequency adaptive generalized integral(GI) controller was introduced in order to suppress the inherent 5th and 7th harmonics in the grid current caused by the dead-zone of the devices. Parameters of the GI controller were directly designed in discrete domain to avoid the undesired loss of high control precise due to discretization process. The simulation and experimental results verify the effectiveness and superiority of the proposed strategy.