In depth: UK green car project
The Engineering and Physical Sciences Research Council (EPSRC) is putting £6m into four year electric car projects lead by Warwick and Loughborough Universities.
They will cover scientific and engineering issues related to: the performance of electric motors and power electronics; and the control and efficiency of electric vehicles sub-systems, respectively.
Brunel University also has £4m to look into making vehicles with recycled and recyclable materials.
“You can put together an electric vehicle now, it is not an issue,” Professor Phil Mawby of the University of Warwick told Electronics Weekly. “What is difficult is making it cost-effectively.”
The Warwick consortium includes Bristol, Nottingham, Cranfield, Newcastle, Sheffield, Strathclyde, Liverpool John Moores and Manchester universities.
Warwick’s speciality is silicon carbide power transistors.
“People say that it is the battery that is expensive, but this is only part of the reason,” said Mawby. “The power electronics people use is mainly developed for industrial applications. They are trying to put those parts into an automotive environment where cost is more important.”
His team will develop car-ready SiC components, replacing 200A silicon IGBTs.
“There are very serious draw-backs to current SiC technology that we are trying to address. RDSon is not as low as it could be because of the interface between the SiC substrate and the SiO2 insulator screws-up the mobility of electrons in the channel,” said Mawby. “We think we know how to fix it.”
Isn’t silicon carbide always going to be more expensive than silicon?
“SiC components are relatively expensive, but the system cost is less. For example, you don’t have to provide water cooling, and they are faster, and more efficient,” said Mawby.
Sheffield, Liverpool John Moores and Cranfield will research motor topologies.
DC motors with rare-earth permanent magnets have a high power density, according to Mawby, but China has out-competed other sources of rare-earth materials, and is now consuming much of its own production.
“So they will study induction, switched-reluctance, and others as well. We don’t know which will win, nobody has done the study,” explained Mawby.
Research into the packaging of power components will be handled by Nottingham, looking at different materials, different solders, alternatives to wire-bonding, and ways to introduce double-sided cooling – as heat is generally from the top of the chip in the drift region, said Mawby.
The University of Strathclyde will develop charging electronics and strategies to interface the battery to the power grid that will minimise charge time.
In order to save the cost of power transistors, Manchester, Bristol and Newcastle will search for circuit topologies that re-use power components in multiple functions – both charging and driving, for example.
Newcastle will also develop modelling techniques for systems and components at various levels.
“You have to understand magnetic components, and you need something faster than finite element analysis for the physics and thermal,” said Mawby, “and you need different techniques for modelling instantaneous heating, or modelling long-term vehicle reliability through heating.”
Transformers, inductors, capacitors and other passives will come under the watchful eye of the University of Bristol.
Industrial partners include Tata motors which has a design centre on site at Warwick, and Jaguar Land Rover, also owned by Tata, which is moving R&D on to the campus.
Is it unusual for a car maker to be getting into electronics?
“Toyota, 20 years ago, entered the power electronics market and now it makes its own components,” said Mawby.
The Loughborough consortium includes the University of Oxford, Imperial College, Cranfield University and Coventry University.
“Our programme’s objectives are better understanding of the basic science of the components in the vehicles of the future,” Professor Rob Thring of Loughborough told Electronics Weekly.
This programme will range widely, largely at a higher level than the one lead by Warwick.
It will include motor-battery control, fault diagnosis strategies, and the study of components including batteries, super-capacitors, fuel cells, electric motors, solid-state power electronics and control systems.
“The automotive industry extremely good at petrol engines and diesel engines,” said Thring. “We are trying to do with electric motors what the industry is good at with petrol engines.”
Examples include: getting more out of a motor and battery with careful attention to the control system, and developing the equivalent of the limp-modes adopted by petrol engines to get home when a fault has been diagnosed.
Technology ‘readiness-levels’ range from one to 10, from blue sky research to full production, said Thring: “We are aiming at levels one, two and three.”
The projects have been developed by EPSRC with the Government’s Technology Strategy Board (TSB) through the Low Carbon Vehicle Innovation Platform Integrated Delivery Programme.