29th January 2019

Insulation degradation and lifetime of inverter-fed machines with fast switching (high dv/dt) converters

Insulation degradation and lifetime
of inverter-fed machines
with fast switching (high dv/dt) converters


Rapid advances in power electronic systems are currently taking place following technological breakthroughs in wide-bandgap (WBG) power semiconductor devices. The enhancements in switching speed, operating temperature, and reduction in losses offered by these devices will impact all sectors of low-carbon industry, leading to a new generation of robust, compact, highly efficient and intelligent power conversion solutions. WBG devices are becoming the device of choice in a growing number of power electronic converters used to interface with and control electrical machines in a range of applications including transportation systems (aerospace, automotive, railway and marine propulsion) and renewable energy (e.g. wind power generators).

The use of WBG devices produces fast-fronted voltage transients with voltage rise-time (dv/dt) in excess of 10~30kV/┬Ás which are at least an order of magnitude greater than those seen in conventional Silicon based converters. These voltage transients, can cause significant overvoltages at machines' terminals and are expected to significantly reduce the lifetime of the insulation of the connected machines, and hence their reliability or availability. This, in turn, will have serious economic and safety impacts on WBG converter-fed electrical drives in all applications, including safety critical transportation systems.

Work program and Impact

The project aims to advance our scientific understanding of the impact of WBG devices on machine insulation systems and to make recommendations that will support the design and test of machines with an optimised power density and lifetime when used with a WBG converter. This will be achieved by quantifying the negative impact of fast voltage transients when applied to machine insulation systems, by identifying mitigating strategies that are assessed at the device and systems level and by demonstrating solutions that can support the insulation health monitoring of the WBG converter-fed machine, with support from a range of industrial partners in automotive, aerospace, renewable energy and industrial drives sectors.