Multi-Domain Virtual Prototyping Techniques for Wide-Bandgap Power Electronics

Lead Research Organisation: University of Nottingham
Department Name: Faculty of Engineering


Power electronics is a key component in a low-carbon future, enabling energy-efficient conversion and control solutions for a wide variety of energy and transportation applications. Power electronics technology enables electric and hybrid vehicles, it is the underpinning technology for the next generation of fuel-efficient "More Electric" Aircraft, and is essential for the operation of high speed rail services. It allows connection of renewable energy sources to the national grid and allows us to more efficiently use the electricity distribution networks we have. In summary, it has the potential to allow almost all electrical devices to become smaller, lighter or more efficient.

Until recently, power electronic systems have been based around Silicon transistors but inherent limitations of these devices present a limit to how small, light and efficient a power electronic enabled system can be. Next generation power electronics will utilise Wide Bandgap (WBG) power transistors, made from materials such as Silicon Carbide (SiC) and Gallium Nitride (GaN) which are able to overcome the limitations of Silicon. This is achieved by having transistors that can operate at much higher frequencies, operate at higher voltages and higher temperatures, and dissipate less of the power they process as heat.

The problem is that our current understanding and experience of power electronic system design is derived from Silicon systems, and that the design of Silicon systems is less critical to achieving optimal performance. To fully exploit the potential of WBG based systems we must understand the challenges posed by the more extreme operating range of WBG devices, and tailor system designs accordingly. High frequency operation means that the electromagnetic design of systems is critical, to avoid unreliable power electronic systems and to prevent power electronic systems affecting other devices through electromagnetic emissions. High frequency operation also theoretically allows the reduction in size of passive filter components (inductors and capacitors) which can significantly reduce system size and weight (increased power density), however the behaviour of smaller passive components operating at higher frequencies is difficult to predict and they can suffer from thermal management problems. High power density power electronic systems, with WBG semiconductors able to operate at higher temperatures place increased thermal stresses on packaging and interconnection methods that were originally developed to deal with Silicon based systems, and this can adversely affect system reliability. An optimal WBG based system design must consider how component choice, system geometry and construction techniques affects each of these challenges, but as the challenges are coupled, any changes to a design to try to solve one problem can cause new problems in another area. Effects such as electromagnetic interference and reliability are also notoriously difficult to predict with extensive experience, and the behaviour of the wide-bandgap semiconductors themselves is different to their Silicon counterparts.

This research will develop the tools that power electronic system designers need to be able to design optimal WBG systems, right-first-time, on a computer - Virtual Prototyping. This will allow faster design times, as fewer physical prototypes must be built, and it will allow engineers with Silicon system experience to quickly develop high performance WBG systems. We will do this by developing mathematical techniques that can be applied to predict how a potential system will behave in the electromagnetic, thermal, mechanical, reliability and semiconductor domains. These techniques will then be combined into a proof-of-concept design tool that will be demonstrated on real wide-bandgap systems developed at the partner institutions, and through parallel work in the linked CA, RHM, and HI projects.

Planned Impact

This project will contribute to the delivery of the underpinning research undertaken within the UK EPSRC Centre for Power Electronics which will reinforce the UK Power Electronics industry by providing it with the knowledge, tools and techniques required to capitalise on the emergence of wide-bandgap semiconductors.
The global power electronic market was estimated to be worth £135bn (2011), growing at a rate of 10% per year[1]. Within this, there is significant interest for the adoption of WBG devices with the market for these alone estimated to increase from $0.25bn in 2016 to $1.25bn in 2020[2]. Knowledge and tools produced by this project have the potential to enable UK industry to capitalise on this growth market and provide significant benefits to the UK economy.

Specific technical outputs include: the development of efficient simulation techniques suited to the multi-domain simulation of power electronics; demonstration of how these techniques can improve the performance of wide-bandgap systems; and an understanding of the multi-domain physics that underpins the successful operation of high frequency, high temperature, and high reliability power electronic systems. Potential beneficiaries of these outputs in the UK are:
- Power electronics system and converter manufacturers who want to realise the true benefits of wide-bandgap power electronic systems
- Producers of design and simulation software who are interested in understanding how novel simulation techniques could improve the performance of their software and how their existing software offerings could be tailored to the power electronics market
- Wider engineering industry who may be interested in how optimally designed wide-bandgap power electronics enhance the performance of their existing products (e.g. automotive or aerospace organisations)
- Ultimately the wider public who will benefit from the small, lighter, more reliable power electronic enabled devices that can result from wide-bandgap power electronic systems, optimally designed using virtual prototyping techniques.

This project will enable the design of power electronic systems that: allow efficient power conversion; enable a cleaner environment through use in electric/hybrid vehicles, rail, 'more electric' aircraft, and ship propulsion; facilitate the use of renewable energy sources and more efficient electricity distribution systems. The project will therefore benefit society by reducing greenhouse emissions and providing opportunity for meeting future CO2 targets.

As part of the Centre for Power Electronics, the project will provide a greater supply of young researchers, PhD students, and engineers and help to address the skills shortage in power electronics through embedding the generated knowledge and skills into undergraduate and postgraduate teaching, technical workshops, and industrial lectures.

This impact plan will be managed as an activity of the Hub of the Centre, through the Executive Management Team and the affiliated Industry Advisory Group as well as through the five topics via four routes:
1. Establish the Centre brand as a natural point of contact for power electronics expertise through active dissemination; build the public image of power electronics/engineering and its importance to society.
2. Promote the transfer of knowledge and IP gained from the research to the UK industrial community and stimulate new business activity.
3. Contribute to the development of relevant policy through engagement with national government, national and international funding bodies and professional societies.
4. Build collaborative links with leading academic groups and other relevant industrial organisations around the world.

[1] "Power Electronics: A Strategy for Success,", UK Government, October, 2011.
[2] R. Eden, "The World Market for Silicon Carbide & Gallium Nitride Power Semiconductors - 2016, IHS Technology," 2016.


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Description The award aims to find fast simulation techniques that can be coupled to allow a comprehensive, virtual evaluation of potential power electronic system designs. Although not yet complete, the work has made progress in a number of areas:
A fast implementation of the Partial Element Equivalent Circuit method for predicting electromagnetic effects in power electronic systems had been completed in software developed under the project. This allows the effect of a potential system's design on its electrical and electromagnetic performance, and efficiency, to be evaluated under realistic operating conditions up to 10 times faster than with a conventional implementation. Limitations of the method have also been explored and understood and mitigation techniques devised.
A method for predicting how power electronic systems wear out and fail when subjected to realistic operating conditions has been devised and implemented in a software tool. This allows the effect of actual, rather than approximate, operating conditions to be used to predict a system's expected lifetime which allows designs to be optimised for reliability in a particular application. This has the potential to reduce cost and increase reliability.

The project has developed strong working relationships between researchers at a three UK universities. A link with the University of Lille in France has also been made which has resulted in two collaborative journal publications to date.
Exploitation Route Software developed within the project could be be developed into a design tool for power electronic system designers, this would need to be through a partnership with a software developer. Such software has the potential to reduce design costs and increase key performance metrics (size, weight, efficiency) of power electronic systems, Smaller, lighter, more efficient power electronic systems are an essential enabling technology in many areas such as the electrification of transportation.

Published technical findings on the limitations of current techniques can be used by other academic researchers to develop better simulation methods for application to electrical systems. This will allow further improvements to software design tools like those developed in this project.
Sectors Digital/Communication/Information Technologies (including Software),Energy

Description EPSRC Centre for Power Electronics - Annual Conference 2018 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact A workshop was held to disseminate information and obtain feedback about the work funded by this grant. As a result of this, a representative from TMD Technologies Ltd made contact and offered to collaborate with the project. A collaboration agreement has been completed and TMD have provided design information for one of their products that is now being used as a validation case for the research software under development in the project. If these trials are successful then we hope that future industry led projects will follow.
Year(s) Of Engagement Activity 2012,2018,2019
Description EPSRC Challenge Network in Automotive Challenge Symposium 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact A presentation of the project's thermal modelling work was made at a symposium for the UK Automotive Industry. Since the meeting, discussions have been ongoing with a UK based engineering consulancy about a future industry led project.
Year(s) Of Engagement Activity 2018
Description Invited presentation at APC Power Electronics and Electric Machines Spokes Symposium 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact A presentation was given on the topic of Modelling of Drives - Advances in Digital Design and Manufacture of Electrical Machines and Wound Components. This resulted in interest in the project's modelling and simulation work from audience members and requests for further information about the project.
Year(s) Of Engagement Activity 2019