Scaling the Dynamic Capacitor (D-CAP) to medium voltages

The concept of Dynamic Capacitor or D-CAP has been previously introduced by the authors. D-CAP is able to provide dynamic VAR and harmonic compensation in one single integrated unit. The topology is based on an AC chopper with the control based on the novel concept of virtual quadrature sources, where energy is exchanged between virtual sources at different frequency, instead of between DC and AC sources such as in voltage source inverters (VSIs). This paper addresses issues pertaining to scaling of the D-CAP to Medium Voltage levels that include safe commutation of the switches, equal voltage sharing, good spectral content, and fault tolerance in direct AC converters such as the D-CAP. Different topologies for scaling to higher voltages with their respective advantages and disadvantages are presented.