A new control method for minimizing the DC-link capacitor current of HEV inverter systems

This paper presents a new control method for boost DC/DC converters combined with voltage source inverter systems to minimize the DC-link capacitor-current RMS value. The examined converter system consists of a multi-phase boost converter and a three-phase inverter with common DC-link capacitor. A general analytical expression for the DC-link capacitor-current RMS value is derived, which allows to optimize the switching pattern for the boost converter phases and the DC-link voltage level. Measurements from a laboratory setup verify the analytical equations and reproduce the calculated values of the RMS current. Since the DC-link capacitor RMS current stress determines the capacitor size and is independent of the switching frequency, this work contributes to a further volume reduction of passive components especially for high frequency converter systems.