Switching loss reduction in converter modules

摘要

The invention relates to converters for converting a DC input voltage a DC or an AC output voltage. The converters have a parasitic inductance. The converters comprise at least one switching element connected to an input terminal for providing a first voltage at an output terminal. In order to allow temporarily storing, in a capacitor, energy induced by the parasitic inductance when switching OFF the switching element, a first series circuit of a diode and a capacitor is provided in the converter, wherein the diode is coupled to the one input terminal. An active circuit coupled in parallel with the diode enables controlling the release of temporarily stored energy from the capacitor of the first series circuit.

主权项

1. A neutral point clamped (NPC) converter for converting a DC input voltage, supplied via a positive and a negative input terminal (701, 702) as a positive and a negative voltage with respect to a neutral terminal (706), to an AC output voltage at an output terminal (703), the NPC converter having a parasitic inductance and comprising:
a first switching element (704) connected to the positive input terminal (701) for providing via an output circuit (730) a positive voltage at the output terminal (703); a second switching element (705) connected to the negative input terminal (702) for providing via the output circuit (730) a negative voltage at the output terminal; wherein the output circuit (730) comprises a first and a second inductor respectively coupled between the first and second switching element (704, 705) and the output terminal (703); a neutral point switching circuit (740; 940) coupled between the neutral terminal (706) and the output circuit (730) for providing a neutral voltage at the output terminal (703); a first series circuit (711) of a first diode and a first capacitor, the first series circuit being coupled between the positive input terminal (701) and the neutral terminal (706), wherein the first diode allows temporarily storing, in the first capacitor, energy induced by the parasitic inductance when switching OFF the first switching element (704); a second series circuit (712) of a second diode and a second capacitor, the second series circuit being coupled between the negative input terminal (702) and the neutral terminal (706), wherein the second diode allows temporarily storing, in the second capacitor, energy induced by the or another parasitic inductance when switching OFF the second switching element (705); a first active circuit (721; 821) coupled in parallel with the first diode of the first series circuit (711) for controlling the release of temporarily stored energy of the first capacitor of the first series circuit (710); and a second active circuit (722; 822) coupled in parallel with the second diode of the second series circuit (712) for controlling the release of temporarily stored energy of the second capacitor of the second series circuit (712).