三相逆变电源不平衡负载控制方法的研究

针对对称分量法实现三相逆变器在不平衡负载下输出电压的正、负、零序分量补偿,以维持三相输出电压的平衡,该方法在三相负载严重不平衡时,其不平衡度仍然较大,且运算量大,适时性差,不易控制等问题.本文提出了一种三相逆变电源的输出电压分相控制的方法,分别对三相逆变器输出的线电压进行控制,以实现三相电压的平衡.理论和仿真分析表明,该方法能够使三相最大不平衡度从传统对称分量法的5.49％降到1％左右,在负载不平衡度达到200％的情况下,三相电压输出也能适时、稳定、可靠的达到平衡,有效地补偿因不平衡负载引起的逆变器输出电压畸变,从而保证逆变器在带任意不平衡负载时仍能维持三相平衡的输出电压.

Study on unbalanced load of three-phase inverter

In the three-phase inverter,although the traditional symmetrical component decomposing and superimpose theory can keep the voltage balance through compensating the positive-,negative-and zero-sequence components of output voltage to maintain the symmetric three-phase output voltage when the three-phase loads are unbalanced,this method is time-consuming,poor real-time and not suitable for control.An individual phase control for output voltage of the three-phase inverter was proposed for controlling individually line voltage to maintain the symmetric three-phase output voltage.The theory analysis and the simulation show that this method can reduce the maximal unbalance degree from 5.49% to about 1% and keep the output voltage balance steadily and timely when the unbalanced loads are 200%.Besides this,it can compensate the output voltage harmonic distorting caused by the unbalanced loads to sequentially maintain the symmetric three-phase output voltage when the inverter operates with any imbalanced loads.