ELECTRIC MOTORS
Batteries hold keys to UK T
he potential impact of the “rules of origin” clause in the Brexit trade deal has struck home with the automotive industry and the race is now on to grow a domestic EV battery industry to generate enough added
value from UK sources to avoid export tariffs that could have a crippling effect. Britishvolt is already planning its first “gigafactory” in Blyth, Northumberland, due for completion within two years and planning is being sought by the authorities in Coventry for a further large-scale manufacturing plant at the airport there, although no tenant has yet been identified for it.
STANDARDS IN PLACE To support local manufacturing, the British Standards Institute (BSI) has released two Publicly Accessible Specifications (PAS). The standards (PAS 7060 & PAS 7062) underpin innovation and enable consistent practices in the production of batteries and development of battery technology. They will support the industry by providing good practice and efficiencies as it works towards its self-sufficient battery manufacturing target. The standards follow the recently released PAS 7061 Batteries for vehicle propulsion electrification code of practice – safe and environmentally- conscious handling of battery packs and modules – which outlines best practice from sourcing material, through to manufacturing, use and disposal.
Domestic manufacturing of automotive batteries is crucial in avoiding future ‘crippling tariffs’ on vehicle exports
ENGINEERING FACILITIES The UK is in a very good position for automotive
engineering development with some of the top global centres resident in the UK. Both Millbrook and HORIBA MIRA have been investing heavily in battery engineering facilities, both being equipped with extensive resources and equipment for development and testing batteries at cell, module or fully installed levels. These facilities include EMC,
Some motors like it hot
Motors that can withstand high temperatures are available for those applications where standard motors cannot stand the heat
S
tandard DC motors have a fairly stable tolerance to temperature up to very strict limits. Most motor manufacturers will specify in the data sheets what these limits are with the majority having a maximum
ambient temperature between 85˚C and 100˚C, with a maximum winding temperature between 100˚C and 125˚C. The reason the ambient temperature is specified comes down to the way the motor works – the electrical supply is divided into voltage (V) and current (A). The voltage determines the speed and
16 /// Testing & Test Houses /// March 2021
the current determines the torque. When in use, the current will generate heat in the winding, so when a motor is specified for operation at high ambient temperatures, it cannot be worked as hard as if it was at regular ambient temperatures, otherwise it will burn out.
PROBLEMS WITH HEAT Inside the motor is a magnetic circuit generated by the permanent magnet and the electromagnet, the motor winding. Both the permanent magnet and the winding are affected by heat. The neodymium magnets start to demagnetise at around 160˚C and become weaker. Unfortunately, cooling the motor does not reverse the effect; it is a permanent degradation. The winding is encased in an insulating varnish which provides stability as well as insulation. As the temperatures increases above 160˚C the varnish softens, and the winding can deform, resulting in rubbing which wears away the
❱❱ Some extreme applications in the energy industry require motors that operate at high
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