低开关频率下三电平同步对称SVPWM算法实现

Implementation of the Synchronization and Symmetries Three-level SVPWM at Low Switching Frequency

大功率应用场合下三电平逆变器开关频率降低,输出电流谐波增大,采取同步且对称的调制策略可优化谐波性能。通过分析同步且对称调制特性,总结三电平SVPWM同步对称的基本条件;详细给出开关规则和具体实现步骤,使输出电压波形在任意整数脉冲下,满足同步、三相对称、1/2周期对称、1/4周期对称。同步对称调制可在低开关频率下消除非特征次谐波,降低输出电流总谐波畸变率。通过Matlab仿真和DSP实验验证了该调制策略的可行性和有效性。

In high-power applications, the switching frequency of three-level inverters was very low so that the output current harmonics increased. With the synchronous and symmetries modulation strategy, harmonic performance was improved. Through analyzing characteristics of achieving synchronization and symmetries modulation, the basic requirements of three-level synchronization and symmetries SVPWM were concluded and the detailed switching rules and implementation steps were given. The modulation maintained output voltage wave synchronization, three-phase symmetry, 1/2-period symmetry and 1/4-period symmetry with arbitrary integer pulses. At the low switching frequency, it is effective to eliminate non-characteristic harmonics and reduce output current total harmonic distortion. Matlab simulation and DSP experiment verifies the effectiveness of the modulation strategy.