A randomized voltage vector switching scheme for 3-level power inverters

In this paper, a feasibility study of a randomized space vector switching scheme for 3-level inverters is proposed. Based on the traditional space vector concept for PWM inverters, the sequence of the space vector is randomized in this scheme. The overall vector, resulting from the randomization, is mathematically identical to that of the traditional space vector. It has been found that the randomized scheme can effectively spread the switching noise over a wide frequency range and at the same time keep the steady-state link capacitor voltage balanced. The proposed scheme has been implemented in a digital controller and its features have been experimentally confirmed.