Influence of N2 pressure on surface discharge characteristics of PEEK under positive repetitive square voltage

Abstract

Abstract PEEK (polyetheretherketone) and N2 are used in the packaging of high‐voltage power electronics as the frame material and insulation gas, respectively. The surface discharge behaviours of PEEK in N2 under positive repetitive square voltage are the main concerns for the packaging insulation design. However, the influence of N2 pressure on discharge characteristics and mechanisms has not been investigated. Herein, the optical images of streamer propagation and surface discharge current pulses of PEEK in N2 with different pressures are obtained under positive repetitive square voltage. The effects of different N2 pressures on the surface discharge initial voltage (SDIV), pulse parameters of discharge current, time lag of discharge and streamer propagation length are analysed in detail. The effects of N2 pressure on the memory effects of residual charges during surface discharge, effective ionisation rate and electron desorption rate are revealed. Furthermore, the time lag theory is used to analyse the influence of N2 pressure on the time lag of forward and backward discharge. The effects of N2 pressure on pulse parameters of discharge current, surface discharge initial voltage and streamer propagation length are also explained on the basis of the process of surface charges accumulation under different N2 pressures. The presented results can provide guidance for the packaging of press pack IGBT (insulated gate bipolar transistor) and reveal the surface discharge mechanism with different N2 pressures under positive repetitive square voltage.

Keywords

• desorption
• insulated gate bipolar transistors
• ionisation
• polymers
• semiconductor device packaging
• surface charging