Partial charging of capacitors for improving voltage profiles of CSI fed motor drives

The fast switching behaviors of wide bandgap devices bring some challenges such as high du/dt and limited short-circuit current withstand capability to the reliable operation of the motor drives. The current-source-inverter (CSI) provides a promising solution in mitigating those challenges by owning the DC-link choke, the reverse-voltage blocking switches and AC commutation capacitors. To further reduce du/dt on switches of CSI fed motor drives, the technique of partial charging of capacitors have been investigated in this paper. By designing the series-connected and the parallel-connected partial-charging circuit for capacitors in DC-link, the voltage profile of CSI could be improved. Specifically, the zero-voltage-switching (ZVS) is achieved for main power switches, the du/dt is reduced and the overvoltage protection is presented. The working mechanism of the technique of partial charging of capacitor is described and one example is discussed on the dual three-phase motor drive. The experimental verification is presented to show the performance of partial charging technique for improving voltage profile of CSI fed motor drives.