Circulating current suppression Control Strategy of parallel Inverter based on reducing Common Mode interference

When using the topology of the parallel inverter to realize pulse width modulation, the characteristics of the even-numbered bridge can greatly reduce or even eliminate common-mode interference, but the resulting asymmetric modulation signal will cause serious differential-mode interference, which is mainly reflected in differential-mode circulating current and zero-sequence circulating current. The asymmetric modulation signal will lead to a large current between the two inverters in one cycle. Although the measure of coupling inductor can reduce the circulating current, it also increases the cost and affects the power density. In addition, there will be current spikes in the sector switching process. In this paper, based on the properties of the even bridge arm, the synchronous control of the six-phase bridge arm is adopted to ensure the inhibition effect of the original modulation strategy on common-mode interference. At the same time, the operation of zero voltage vector substitution (ZVVS) and voltage vector sequence reconstruction (VVSR) greatly reduces the peak amplitude of cyclic current and the current change speed during sector switching. Finally, this paper verifies the improvement effect of the algorithm on the circulation by comparing the simulation results before and after the improvement of the algorithm.