On the series connection of insulated gate power devices

The series connection of insulated gate devices (IGBTs and MOSFETs) is treated with reference to different approaches which ensure a balanced voltage sharing. Both load-side and gate-side techniques are discussed, and their merits and demerits are highlighted. A novel approach, which intervenes during the rise time or fall time of the collector voltages, is discussed and compared to the alternative solutions. Laboratory tests on two IGBT devices are carried out according to the analyzed techniques. Finally, the disadvantages of the multiple connections are discussed in terms of switching speed reduction and power loss increase