PROJECT TITLE :

Power Decoupling Control for Capacitance Reduction in Cascaded H-Bridge Converter-based Regenerative Motor Drive Systems

ABSTRACT:

A medium or high-voltage motor drive system based on three single-phase CHB chains may suffer from a severe second-harmonic ripple power issue. It is feasible to overcome this issue by increasing the capacitance of the dc capacitors or by employing active power decoupling control with extra active or passive components, but this comes at a price. This research presents a power decoupling control for regenerative CHB-based converters without the need for additional components. For each submodule's pulsewidth-modulated rectifier, it is possible to remove the second-harmonic ripple power from its dc capacitors, and all the ripple power in the transformer core legs can be counteracted without affecting magnetic flux or the grid current by introducing negative-sequence decoupling currents. The CHB converter's input and output data are used to calculate the decoupling current. Modulation index is increased by a tiny amount, with no affect on the quality of either input or output power. A 72-kW experimental prototype and simulations show that the suggested control is effective.