Global electric vehicle makers are gradually adopting copper-based rotar motor technology instead of the magnet-based motors to power the new breed of vehicles, according to Mr Hal M. Stillman, Director of Technology at International Copper Association Ltd.
Mr Stillman told Business Line “electrical vehicle manufacturers are set to take off all over the world to avoid pressure on use of fossil fuels for transportation. All these years, the main technology used in electrical vehicles is based on use of permanent magnets.
Short supply
“There is clear short supply of permanent magnets required to power possibly millions of vehicles in future. China continues to be a major provider of magnets and manufacturers are wary about its steady supply,” he explained.
“Most electrical electric vehicles and hybrid cars today use permanent magnet motors. But the technology developed in the recent years promises to change this. These manufacturers have begun to deploy die cast copper rotary motors which bring in same levels of efficiency while being substantially lower in cost,” he said.
Lower costs augured well as volumes are likely to grow to address environment and due to Government subsidies. With batteries too getting better and helping run up to 300 km for full charge, the adoption of electric vehicles is poised to accelerate.
“The technology developed by Non-Ferrous Material Technology Development Centre (NFTDC) would be useful for rotary die cast rotors for hybrid vehicles. We believe that this can take lead in helping popularise the use of rotary motors for electric vehicles,” he said.
Copper use
He said the use of copper for the conductor bars and end rings of induction motors in place of aluminium, results in improvements in motor efficiency. Until recently, die cast motor rotors were universally produced using aluminium pressure die casting. Now, developers have identified and demonstrated durable mould materials that have enabled economical production of die-cast copper motor rotors.
Chinese authorities have reduced supplies of magnets. Vehicle manufacturers, worried about steady supply magnets and other rare earth materials, are looking at reliable alternative technology such as copper.
Companies such as Tesla, Toyota are popularising other options. Some have both options magnets and rotors. He said copper motors are efficient, small in size, have better thermal management, operate in wide seed and range. They can address challenge of dependence on rare metal supply.
Magnet motors
The internal permanent magnet motors are used for automotive propulsion in electric vehicles. These motors do not have a field winding in the frame and rely on magnets to provide magnetic field. These motors are said to be convenient as they are smaller and efficient. To minimise weight they use neodymium or other strategic elements.
In contrast, induction motors use die cast copper rotors. These are now being considered as alternatives as they reduce electrical losses. Due to its heat conduction properties, they make it ideal for use in vehicles. An induction motor is like a rotating transformer where power is transferred to the rotor by electromagnetic induction.