Cascaded converters for EVs with single power source and increased power quality.

Abstract

This paper is based in a cascaded multilevel converterconformed by two 3-level inverters connected in series. The voltage sources of the auxiliaryinverter were replaced by floating capacitors which work as active filters, reducing the power sourcesto one. The floating capacitor voltages were controlled by a PI controller that adjusts the modulationindex (m) to obtain a zero average power in the auxiliary inverters, and a predictive control selects theoptimal redundant state to reduce the error and balance all the capacitor voltages. As the modulationindex is determined by the PI controller, the output voltage magnitude must be controlled by avariable voltage source (e.g. buck-boost chopper). Additionally, the converter works with new optimalvoltage asymmetries to obtain higher power quality and capacitor control stability.