Advantages of IGBT Series Connection in 1.500 V PVinverters

A series connection of two conventional 1.200 V rated IGBTs allows a maximum blocking voltage of 2.400 V in theory. With respect to overvoltage during the switching process and the impact of cosmic radiation, the voltage stress of a single 1.200 V device should not exceed 70 % to 75 % of the rated value to achieve a trade-off in lifetime and voltage resulting in a maximum blocking voltage of 1.800 V for a series connection. Within this paper the voltage sharing between the IGBTs will be investigated and the behavior of a newly developed balancing method will be shown. Moreover advantages and challenges of the IGBT series connection are discussed for large-scale PV-inverter systems.