A novel dual-section space vector PWM for three-level rectifier

In two-dimensional abc-coordinates system, the effects of medium vectors and small vectors on the neutral point are analyzed and derived. Because the small vectors in pair have opposite effects on the neutral-point potential (NPP), the medium vectors are considered as the most important factor that lead to the neutral-point potential imbalance (NPPI). The dual-section space vector PWM is proposed in this paper. The NPPI led by medium vectors has been dramatically eliminated in this PWM. At the same time, the four-quadrant mirror-image algorithm and adjustable neutral point balancing factor are introduced to improve the running efficiency of three-level PWM rectifier. The simulating result shows that the algorithms adopted in this paper are correct, and they have made the programming of controller simpler. Specially, the NPP has been excellently balanced too.