Motor drives and other power conversion systems typically receive AC input power and convert that to an internal DC for subsequent conversion to AC output power for driving a motor or other load.  Multilevel inverters are sometimes used in motor drives to generate and provide high voltage drive signals to the motor in high power applications.  One form of multilevel inverter is a Cascaded H-Bridge (CHB) inverter architecture, which employs multiple series-connected H-Bridge inverters for driving each motor winding phase.  Each H-Bridge is powered by a separate DC source and is driven by switch signals to generate positive or negative output voltage, with the series combination of multiple H-Bridge stages providing multilevel inverter output capability for driving a load.  Various modulation techniques can be used for generating the CHB switching signals, such as phase shift pulse width modulation (PS PWM) and level shift pulse width modulation (LS PWM).  In any power conversion system, reducing Total Harmonic Distortion (THD) is an important design goal.  Accordingly, level shift PWM is commonly used for generating the CHB switching signals in multilevel voltage source medium voltage inverters for motor drive applications, as this provides better output line-line voltage THD than phase shifted PWM, and does not generate certain additional dv/dt problems associated with PS PWM.  However, LS PWM has certain shortcomings for high power converters due to uneven power distribution, and this technique can lead to increased input current harmonics.  In particular, individual input rectifiers are loaded unevenly, especially at lower output modulation indices, where device switching frequency is not equal to carrier frequency and is not the same for all switches.  Accordingly, a need remains for improved carrier-based pulse width modulation techniques and multilevel inverters for driving motors and other loads.