Minimization Of Switched Capacitor Voltage Ripple In A Multilevel Dodecagonal Voltage Space Vector Structure For Drives

Minimization of Switched Capacitor Voltage Ripple in a Multilevel Dodecagonal Voltage Space Vector Structure for Drives

Abstract:

            Multilevel dodecagonal voltage space vector generation scheme for variable speed drive applications with single DC link operation requires large value of capacitance for cascaded H-bridge (CHB) filters, when operated at lower speeds. In existing schemes, multilevel dodecagonal structure is obtained by cascading a flying capacitor inverter with a CHB. In this paper, a new scheme has been proposed to minimize the capacitance requirement for full speed operation by creating vector redundancies using modular and equal voltage CHBs. Also, an algorithm has been developed to optimize the selection of vector redundancies among the CHBs in order to minimize the voltage ripple of the floating capacitors. The proposed algorithm considers instantaneous capacitor voltages and phase currents for optimal selection of vector redundancies.