基于中压大功率变流器的新型双调制波载波的三电平PWM控制策略

A New Tri-level PWM Control Strategy for Bi-phase Modulation Wave Carriers Based on Medium-voltage High-power Converter

随着风力发电机型向着大功率、高电压方向发展,现在PWM发波电路拓扑逐渐由两电平过渡到三电平。针对中压大功率变流器提出了新型的双调制波载波的三电平PWM控制策略。新型的双调制波载波PWM发波策略和传统的SVPWM具有等效的调制度,相比传统的SVPWM,具有算法编程简单,运算效率高,节省代码空间,易于实现,能实现抑制母线电压中点电位低频波动和直流波动。PWM发波的更新时刻由三角波载波单周期更新时刻改为双周期更新,等效提高了开关频率,使得控制电流具有更低的谐波。PWM发波的保护逻辑由硬件电路实现。新型的双调制波载波PWM发波策略已经在数学软件里进行离线仿真和硬件在环的基于电力电子的半实物平台仿真,最后新型的双调制波载波PWM发波策略运用在了4 MW的中压大功率变流器,具有良好的效果。

With the development of wind turbine toward the high power and high voltage type,for the PWM wave-generating circuit topology,the two levels are gradually transitioned to three levels.In this paper,a new tri-level PWM control strategy with bi-phase modulation wave carrier is proposed for medium-voltage high-power converter.Compared with the traditional SVPWM,the new bi-phase modulation wave carrier PWM wave-generating strategy has an equivalent modulation degree with simple algorithm programming,high computing efficiency and smaller code space,which is easy to realize and restrain the low-frequency fluctuation and DC fluctuation at the neutral point potential of the busbar voltage.The updating time of the PWM generating wave is changed from the single-cycle updating time of the triangular wave carrier to the double-cycle updating time,which equivalently improves the switching frequency and makes the control current have lower harmonic wave.The protection logic of the PWM wave is implemented by the hardware circuitry.The offline simulation in the mathematical software and hardware-in-the-loop semi-physical platform simulation based on the power electronics have been carried out for PWM wave-generating strategy with new bi-phase modulation wave carrier and finally the PWM generation strategy with new bi-phase modulation wave carrier has been applied on 4MW medium-voltage high-power converter with good effects.