source：RIDE by Kelley Blue Book
Most electric motors use rare earth magnets, which are not only expensive but require environmentally-damaging mining practices to produce. Advanced Electric Machines (AEM), a company formed for the singular purpose of redefining automotive and aerospace propulsion, recently won the coveted, Collaborate To Innovate award in the automotive sector for its new High Density Switched Reluctance Motor, or HDSRM, which doesn’t use magnets or copper.
DC Electric motors use rare earth magnets, the construction of which is bad for the environment.
They also require copper windings, which are heavy, expensive and tough to recycle.
Although HDSRMs have been built and tested in the past, AEM’s design solves many of the downfalls that have kept them from achieving success.
AEM’s design works with pre-existing motor controllers, meaning they can be easily adapted to current car designs, don’t produce torque-ripple and are substantially cheaper to build.
A traditional permanent magnet electric motor uses a stator, which is the outside case, housing rare earth magnets. Inside the case is a rotor, which is wound in copper wire. The electric current is controlled by a device called the commutator. As the current is switched in the copper windings, the rotor is attracted or repulsed by the magnets causing motion.
AEM’s HDSM is similar to other switched reluctance motors, in that it moves the heavy windings from the rotor to the stator(case), meaning they no longer spin. And, instead of using permanent magnets, the rotor is made from laminated steel. Instead of a mechanical commutator, the motor is controlled by electronics.
Replacing rare earth magnets is a huge step forward for the environment. Like the rare earth elements needed for battery production, the mining is responsible for large amounts of carbon dioxide emissions as well as other environmental impacts. Not only that, China currently produces the lion’s share of the world’s supply, so prices and availability are in constant flux. Eliminating the rare earth elements and replacing them with regular steel is a boon in terms of budget and deliverability.
Only slightly less important on the materials side, is AEM replacing the copper windings with aluminum. Copper is difficult to recycle, it’s heavy and is roughly 10-times the price of aluminum.
Lighter, cheaper and better; the HDSRM seems like a winning proposition. After winning the Collaborate To Innovate award, AEM is wasting no time getting the motor into to production. It will see service in the beginning of 2020, appearing first in large commercial trucks and city busses. The company can only produce around 12,000 per year right now, but in the near future, you will start seeing HDRSMs in consumer electric vehicles.