Method for commutating a current in an electronic power converter phase from a reverse-conducting IGBT in a diode mode to a reverse-conducting IGBT in an IGBT mode

摘要

The invention relates to a method for commutating from a reverse-conducting IGBT (T1) operated in the diode mode to a reverse-conducting IGBT (T2) operated in the IGBT mode. According to the invention the reverse-conducting IGBT (T1) operated in the diode mode is turned off only at the instant a current starts to flow in the reverse-conducting IGBT (T2) operated in the IGBT mode. Accordingly said commutation method is event-driven, as a result of which it is less sensitive to poorly toleranced operating times.

主权项

1. A method for commutating from a first reverse-conducting IGBT operated in a diode mode to a second reverse-conducting IGBT operated in an IGBT mode, said first reverse-conducting IGBT and said second reverse-conducting IGBT electrically connected in series and forming a power converter phase, with the series connection being electrically connected in parallel with a direct-current voltage source, the method comprising the steps of:
a) detecting that a control signal of the first reverse-conducting IGBT has switched to an off-state and turning on the first reverse-conducting IGBT after a first predetermined time period has elapsed, b) detecting that a control signal of the second reverse-conducting IGBT has switched to an on-state and turning on the second reverse-conducting IGBT after a second predetermined time period has elapsed, wherein the second time period is substantially greater than the first time period, and c) turning off the first reverse-conducting IGBT when a measurement voltage induced in a saturable transformer by a zero crossing of a collector current in the first reverse-conducting IGBT that is caused by an onset of a current flow through the second reverse-conducting IGBT exceeds a predetermined threshold value.