investigation of rcd snubber voltage balancing technique for series-connected igbts in inverters

This paper investigates a voltage balancing techniquebased on rcd snubbers for series-connected igbts in highpower dc/ac applications. in voltage source inverters, bidirectional current capability is mandatory, and incertain intervals within a switching period, the load currentpasses through the reverse parallel diodes while the higher/lowerarm igbts are in their off-state. thus, the voltage acrossseries-connected igbts will be determined based on the reverserecovery charge of igbts’ anti-parallel diodes. the reverserecovery charge of the diode profiles changes dramatically withits junction temperature. as a result, existing voltage balancingmethods for series-connected igbts to equate the voltage acrossseries semiconductor devices are no longer effective due totheir practicality for unidirectional current flow. rcdsnubbers can be effectively used in parallel with each igbt inseries for inverter applications to balance their voltage in vsis.the proposed scheme is simulated for a case study using pspicesoftware.