Suppression of common-mode voltage spectral peaks by using rotation reverse carriers in sinusoidal pulse width modulation three-phase inverters with CFM

The common-mode interference in three-phase inverters is a prominent problem and is hard to be suppressed. The common-mode voltage (CMV) is an important source of common-mode interference. The spectral peaks of CMV can be suppressed markedly through carrier frequency modulation (CFM) in three-phase inverters. The multi-carrier technology can be used to further suppress the spectral peaks of CMV, but it is not easy to achieve in the CFM case because of the changing carrier frequency. A new method, which is named the rotation reverse carriers (RRC) scheme, is presented to solve this problem here. In this scheme, the three-phase carriers reverse in turn so that some peaks can be counteracted in the CMV spectrum. This leads to a further reduction in spectral peaks of CMV based on the effect obtained by using CFM. Using the RRC scheme can also ensure the balance of three output voltages. In order to reduce the adverse effects on differential-mode characteristics, the RRC scheme is also optimised here. The total harmonic distortion is lowered by the use of an optimal RRC scheme. The feasibility and effectiveness of the proposed RRC scheme are verified by the simulations and experimental results in a three-phase inverter.