A Comprehensive Double-Vector Approach to Alleviate Common-Mode Voltage in Three-Phase Voltage-Source Inverters with a Predictive Control Algorithm

In this paper, a comprehensive double-vector approach is proposed to alleviate the common-mode voltage of voltage-source inverters based on a model predictive control scheme. Only six active vectors are selected to alleviate the common-mode voltage. Furthermore, one sampling period must be split to apply two non-zero vectors, which can generate currents with small current ripples and errors, despite not using zero vectors. The developed algorithm regards in full all 36 possible cases combined by two non-zero active vectors when selecting two vectors and splitting them into one sampling period. Thus, an optimal future set of two non-zero active vectors and optimal durations of two non-zero active vectors to produce the smallest current errors between the real currents and the reference in future load current trajectories were selected from 36 entire sets. This was done to minimize the cost function defined at the time when it varies from the first vector to the second vector and at the next sampling instant. Thus, the proposed algorithm can control the output currents with a fast transient response and reduce output-current ripples and errors, as well as alleviate the common-mode voltage to +/- Vdc/6.