What I Learned from Buying a Tesla? Consumer Ignorance about EVs
Does Anyone Know What a IPMsynRM Motor is?
I recently bought a Tesla Model 3. So did about a quarter of a million other people in the U.S. alone. With all those new owners driving around in what is undeniably a very different kind of car, there are sure to be hundreds of blogs and articles and YouTube videos on the topic, with titles that start with “What I learned…” or “What you need to know….”
These amateur reviewers will tell you about some of the (many) irritating quirks of the vehicle as well as surprising or hidden features. But the information they give tends to be superficial. They will tell you where to find extra USB charging ports, how to turn on “sentry mode” when you park the car in a sketchy neighborhood, and what you might need to do to charge the car at home. But they have little to say about the nuts and bolts of the car, about what makes it tick.
The lesson I learned after purchasing a Tesla is not about the car or what it is like to own or drive one. Instead, what I learned is more about myself and the general buying public. Even car-savvy consumers are surprisingly ignorant about electric cars.
Though I have only owned a few cars in my lifetime, and none of them particularly exciting (until now), I still consider myself a bit of a gearhead. I watch Top Gear and Donut Media videos. I study car history and keep up on the latest technology. I understand the mechanics of VTEC (Honda’s Variable Valve Timing & Lift Electronic Control); I know the difference between genuine torque vectoring (which employs a clutch pack on the axel) and traction control systems (which rely on the cars breaks); and I appreciate why performance car enthusiasts prefer naturally aspirated engines (turbo lag).
So imagine my surprised when I discovered, after purchasing my Model 3 Dual Motor AWD Tesla, that my new car had a new kind of electric motor — one that works differently from the electric motor in most other electric cars, including earlier Tesla models.
I just dropped fifty grand on a car without knowing anything about its power-train. It would be like purchasing a Mazda RX-7 without realizing that it has a Wankel rotary engine. Or like buying a Toyota GT 86 (aka Subaru BRZ) and not knowing that it has a front mounted boxer engine.
Some people might shrug, “Whatever.” I imagine those are the same people who would buy a gas-powered car without knowing how many cylinders the engine has or whether it powers the front or rear wheels. Not everyone shares my enthusiasm for automotive engineering, and that’s fine. What is strange is that even those who are as into cars as much as I am have no idea what makes the new motor design different, or even that there is a new motor design.
So What is this Fancy New Motor?
Once I learned about the new motor, I did some research. For those who are as interested in automotive technology, here is a quick summary. (If you are not interested in engineering, you might want to jump to the next section.)
Prior to the Model 3, electric vehicles pretty much all used something called an “induction motor,” roughly the same motor invented by the company’s namesake, Nikola Tesla. But the Model 3 introduced a different design, the IPMsynMR motor.
So what makes the new motor special? Let’s start with the basics. Virtually all electric motors — including the old induction version and the new IPMsynRM — have a cylinder called a “rotor” that spins inside a stationary hollow cylinder called the “stator.” The stator is lined with electromagnets that are turned on and off in sequence, creating a rotating magnetic field that turns the rotor. The Stator is roughly the same in different motor types; what varies is the design of the rotor.
In the induction motor, the rotor consists of metal bars running the length of its axis at a slight angle. This design is called a “squirrel cage,” though the term “hamster wheel” might be more appropriate. The rotating magnetic field causes an electric current to flow through the bars, called an “induced” current. This current creates a magnetic field around the bars of the rotor, which respond to the rotating magnetic field of the stator. Pretty simple.
Electric motors are incredibly efficient, converting more than 90% of electrical power into kinetic energy, unlike internal combustion engines, the most efficient of which convert less than half of the chemical energy in the gasoline into kinetic energy. (The rest is converted into heat.) Still, the induction motor is not as efficient as it could be. Some of the electricity is used to create the current in the bars of the rotor. And the rotor cannot spin as fast as the magnetic field created by the stator, because that would cut off the current in the bars of the rotor.
The new Tesla 3 combines two alternative electric motor designs, the IMP and the synRM.
First the IPM. One way to improve on the induction motor is to replace the squirrel cage style rotor with permanent magnets. This is an “IPM,” or internal permanent magnet, motor. (It is internal because the permanent magnets are in the rotor, not the stator.) It requires less energy than the induction motor because no electricity is lost in creating induced current the rotor. But the rotating permanent magnets can interact with the electromagnets of the stator at high rpms, resulting in loss of power.
Another solution is the synRM motor. The rotor in this design consists of a solid metal cylinder with curved slots removed. The magnetic field of the stator flows through the solid part but not the slots, causing the rotor to orient itself to line up with the magnetic field — a phenomenon referred to as “reluctance.” As the magnetic field turns, the rotor turns with it at the same speed. This is a synchronous reluctance motor, or synRM.
Telsa’s new IPMsynRM motor simply combines the two designs, placing permanent magnets into the slots of the synRM rotor for the best of both worlds.
Why didn’t I already know all that?
Consumer Ignorance
I do not expect very many people to understand how the IPMsynRM works. I do not fully understand it myself, as I’m sure some readers will be eager to point out in the comments. But I have yet to meet anyone, even among fellow Tesla 3 owners, who are even dimly aware that there are different kinds of motors available in today’s EVs.
So, why are otherwise well-informed drivers ignorant about electric motors? Is it because the technology is so new? I doubt it. The induction motor has been around for one hundred and thirty years. Perhaps it is because electric cars have only been widely available for about fifteen years, and still make up only 3% of all car sales in the U.S. (and even less worldwide). Maybe. But I have another explanation.
I think it has more to do with marketing. While many auto manufacturers tout their high performance engine designs, with badges declaring “V-8” or “V-12,” “turbo,” or “kompressor” (the German word for supercharger, found on some Mercedes), Tesla seems more interested in promoting their vast charging network and the computer technology installed in their vehicles, such as autopilot, cell phone keys, and upgrades that can be downloaded.
In many ways Telsa Motors presents itself more as a tech company than a car company. And I think that is unfortunate, because it is a pretty damn exciting car.
