A method of balancing the voltage of DC links in a cascaded multi-level
converter (CMC) semiconductor circuit, including the steps of providing a
plurality of H-bridge converters per phase in the CMC circuit and
utilizing a three phase duty cycle value from the main controller to
determine a normalized duty cycle value, a ceiling duty cycle value and a
floor duty cycle value. The normalized duty cycle value and an output
current of the CMC is used to determine the direction and polarity of a
capacitor current, and utilizing the capacitor current to determine a
plurality of output capacitor voltages. A voltage summation result and
direction is obtained from a ceiling index pointer and a floor index
pointer and the voltage summation result, direction from the ceiling
index pointer and a floor index pointer are used to create a combined
switching table for the H-bridge converters. A pulse width modulator is
utilized to balance the voltage of the DC links and thereby eliminate
DC-capacitor voltage imbalance.