Abstract:

With the development of bidirectional power conversion system (PCS) towards high voltage and high efficiency,SiC devices are gradually being applied in bidirectional PCS.The PCS main circuit topology of SiC adopts a T-type three-level inverter circuit that can effectively reduce grid connected current harmonics.Aiming at the high switching frequency of SiC devices,the phase-locked control based on phase voltage sampling is more susceptible to interference,and the system stability is easily affected when the power grid is unbalanced,a phase-locked loop based on line voltage sampling and the corresponding positive and negative sequence separation control strategy of grid-connected current are proposed.Finally,a 10 kW bidirectional PCS experimental prototype based on SiC is built,which shows good performance and stable and reliable operation.The experimental results verify the correctness and effectiveness of the design scheme and control strategy.

Key words: bidirectional power conversion system, T-type three-level inverter circuit, silicon carbide, control strategy