A Change in Motor DesignThe 2017 Tesla Model 3 sedan uses a permanent magnet electric motor instead of the AC induction motors used in all Tesla products to date. | August 16, 2017 | Tesla
The big news is this: the Model 3 uses a permanent magnet (PM) electric motor instead of the AC induction motors used in all Tesla products to date.
It may sound like a nerdy difference, but this is a huge deal on many levels. Tesla's entire identity is tied up with the AC induction motor, a type that Nikola Tesla himself patented in the late 1880s. Not only that, the Tesla logo is said to be a cross-section of one lobe of one of its own AC induction motors. Tesla is the only production electric carmaker with this type of motor, so it has historically bad-mouthed the PM motors used by everyone else. Tesla liked pointing out that PM motors tend to be less efficient when operated at higher speeds. Also, such motors are made from rare earth elements, which are mostly mined in China and are thus subject to trade politics. No wonder Tesla didn't feel like revealing this nugget at the Model 3's coming-out party, which was well-attended by Tesla fans who are invested in the Tesla story.
But none of this is bad news for consumers or deposit-holders waiting in line to buy a Model 3. In fact, it's a good thing. For one, PM motors are more efficient, so long as you're not intent on building a hyperperformance machine. This makes them a better choice for daily-driven commuter vehicles. Not to oversimplify it too much, but AC induction motors have to use some of the electricity stored in the car's battery to generate the necessary magnetism within the motor. Permanent magnet motors have no need for this because they are made using, as the name suggests, permanently magnetic materials.
This change has many cascading benefits, especially if you are trying to build a smaller, less-expensive electric car. A more efficient electric motor means you can use a smaller battery to achieve a given range, which not only lowers the price, but also reduces the battery's weight and footprint. A smaller and lighter battery in turn allows for a smaller and lighter car, which increases efficiency and range and reduces the need for a big motor even more. It's a self-reinforcing change that makes the Model 3 possible, as well as affordable.