A delta-configured auxiliary resonant snubber inverter

A delta (/spl Delta/)-configured auxiliary resonant snubber inverter is developed to overcome the voltage floating problem in a wye (Y)-configured resonant snubber inverter. The proposed inverter is to connect auxiliary resonant branches between phase outputs to avoid a floating point voltage which may cause overvoltage failure of the auxiliary switches. Each auxiliary branch consists of a resonant inductor and a reverse blocking auxiliary switch. Instead of using an antiparalleled diode to allow resonant current to flow in the reverse direction, as in the Y-configured version, the resonant branch in the /spl Delta/-configured version must block the negative voltage, typically done by a series diode. This paper shows single-phase and three-phase versions of /spl Delta/-configured resonant snubber inverters and describes in detail the operating principle of a single-phase version. The extended three-phase version is proposed with nonadjacent state space vector modulation. For hardware implementation, a single-phase 1-kW unit and a three-phase 100-kW unit were built to prove the concept. Experimental results show the superiority of the proposed topology.