Electric Field Analysis of Press-Pack IGBTs

High voltage IGBT module is the ideal option for the VSC-HVDC power transmission application. At present, wire-bonded technology and press-pack technology are available packaging technologies for high voltage IGBT. The press-pack IGBTs have such advantages as low inductance, low thermal impedance and short circuit failure mode than the wire-bonded IGBT module, which especially suit for high voltage power transmission application by series connection. However, the electrical insulation failure modes of press-pack IGBTs are much less known with limited literature published. In this paper, we presented the electric field analysis of a 3D press-pack IGBT model under DC rating voltage test condition. The electric field distribution of the press-pack IGBT stack was solved as an electrostatic problem by employing the finite element method. The results revealed the potential electrical insulation failure modes of the press-pack IGBTs: corona discharge at the edge of silver plate, partial discharge at the micro gap between die and PEEK frame and creeping discharge at the surface of PEEK frame.