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

Lead Research Organisation: University of Sheffield
Department Name: Electronic and Electrical Engineering


Rapid and transformative advances in power electronic systems are currently taking place following technological breakthroughs in wide-bandgap (WBG) power semiconductor devices. The enhancements in switching speed and 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). However, the use of WBG devices produces fast-fronted voltage transients with voltage rise-time (dv/dt) in excess of 10~30kV/us which are at least an order of magnitude greater than those seen in conventional Silicon based converters. These voltage transients 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.

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.

Planned Impact

The UK's commitment to creating a low-carbon economy aiming at an ambitious reduction of 80% in CO2 emissions by 2050 will require significant investments in electrical machines and drives technologies underpinned by advances in power electronics both in the generation sector (e.g. wind power) and in consumption. Electrification in automotive, marine, railways and aerospace applications will dominate investments in the transportation industry in the foreseeable future amounting to an economy worth more than £50Bn worldwide and £2Bn in the UK by 2020. The sector is attracting significant investments in R&D and manufacturing in the UK by many global players, including Jaguar Land Rover, Rolls-Royce, United Technologies Corporation, Siemens, and Airbus, etc.

The research conducted in this project will tackle timely the fundamental challenges for applications of wide-bandgap devices in electrical machines and drives, and directly address the EPSRC "Resilient" (Ambitions R1, R4, R5) and "Productive Nation" (Ambition P1) prosperity outcomes and ambitions. It will also directly support the development of the next generation of technologies for the efficient and resilient provision and utilization of clean energy and contribution to low carbon transportation systems. The project will have a significant direct impact on the:
- UK industry by generating knowledge and IPs which will ultimately help the UK maintain and expand its position as a major player in energy conversion technologies, safety critical electric and hybrid-electric propulsion systems, asset management and condition monitoring solutions;
- Society, by developing research that will underpin the development of disruptive advances in the low-carbon technologies, leading to reduced emissions, cleaner transportation (electric/hybrid vehicles, rail, 'more electric' aircraft systems, ship propulsion) and higher efficiency in energy generation and conversion;
- Academia by delivering new scientific breakthroughon modelling tools, design methods, control and condition monitoring technologies that will enhance UK standing in the international arena;
- UK skilled workforce by training young researchers, PhD students and personnel from industrial partners addressing an area with significant skills shortages.


10 25 50