Carrier-based PWM for Z-Source Inverters

Z-Source Inverters have the ability to boost the dc link voltage, thus increasing the output ac voltage beyond the values reached by conventional inverters. The enhanced ratio from ac output voltage to dc link voltage is possible due to an impedance network connected between the dc power supply and the main converter. In order to boost the voltage, shoot-through states are needed. Shoot-through is produced by the inverter legs, thus shoot-through states have to be embedded into the modulation. Moreover, root-mean-square values of current and voltage in the Z-source depends on the modulation technique. Therefore, the inverter efficiency also depends on the modulation. This paper presents one way to embed shoot-through states in a standard carrier-based PWM. This novel technique is easy to implement, assures the best dc link utilisation, avoids extra switching for the shoot-through states, and equates the conduction losses obtained by other z-source modulators.