There was a time not long ago when the electric car was no more than a futuristic concept. Now, with an estimated 5.6 million vehicles globally (and counting), EVs (electric vehicles) are here to stay while continuing to transform transportation in the modern world. Electric cars are modern science on four wheels with mind-blowing features inside and out, but what about under the hood?
Depending on the type of vehicle and desired performance characteristics, electric cars can use either an AC or a DC motor. However, the overwhelming majority of mass-produced electric cars today use one of several AC motor types, including most notably:
- Induction Motors
- Permanent Magnet Motors
DC motors are more than adequate at providing decent torque and acceleration at lower speed ranges and maintaining respectable cruising speeds. Still, the advent of highly sophisticated controls has brought AC motors to the forefront in the EV arena. As technologies continue to develop at a blistering pace, it is easy to see why electric car manufacturers are going all-in on AC motors.
Do Electric Cars Use AC or DC Motors?
When it comes to electric cars, there are two general categories that they fall into:
- Those that are powered by AC motors
- Those that use DC motors
Generally speaking, whether a particular electric car uses an AC or DC motor is a complex manufacturing decision involving engineering and financial considerations. Both types of electric car motors have their advantages and disadvantages.
AC (alternating current) motors currently dominate the EV landscape, as evidenced by the lengthy and illustrious list of electric car manufacturers that use them in their vehicles (more on this later). But this is not to say that powering electric cars with AC motors is not without its challenges. Here is a look at the pros and cons and general characteristics of using AC motors:
|Lightweight construction (allows for greater range and higher speed)Most types are cost-efficient and require minimal maintenanceCertain types (induction) can withstand rough environmentsHigh efficiencyHigher maximum RPM (which translates to power and speed)All-around high performance in terms of torque, efficiency, and top-end speed||Require highly sophisticated and costly electronics (especially the controller and inverter)Permanent-magnet type AC motors have high potential costs due to limited availability and price volatility of rare-earth materialsExtensive cooling measures required to prevent overheating and damage to componentsPotential efficiency loss at higher speeds|
DC (direct current) motors are considered to be the simplest in their design and the most straightforward to control. While they are still commonly found in smaller modes of transportation like e-bikes, they are not commonly found in modern, mass-produced electric cars, particularly those from major manufacturers. Here are the main advantages and disadvantages of DC motors in EVs:
|Robust and durable constructionStraightforward controlProduce high torque at low speedsRelatively inexpensive and cost-effectiveCertain types (e.g., brushless) have a highly efficient operation||Tend to be quite large in sizeCertain types are inefficient (especially brushed motors)Potentially high maintenanceOverheating concernsLimitations in speed control and variability|
The Best-Selling Electric Cars Use AC Motors
One needs to look no further than popular electric car makes and models to see that AC motors are the technology of choice to power the vast majority of EVs that are being driven around the world today. The table below tells the whole story as far as the prevalence of AC motors found in today’s best-selling electric cars:
|RANK||MAKE AND MODEL||TYPE OF MOTOR|
|1||Tesla Model Y||Front: Induction Motor (AC) Rear: Permanent-Magnet Synchronous Motor (AC)|
|2||Tesla Model 3||Permanent-Magnet Synchronous Motor (AC)|
|3||Chevrolet Bolt||Permanent-Magnetic Drive Motor (AC)|
|4||Ford Mustang Mach-E||Dual Permanent-Magnet Synchronous Motors (AC)|
|5||Tesla Model X||Dual Asynchronous Motors (AC)|
|6||Audi e-tron||Dual Induction Motors (AC)|
|7||Tesla Model S||Front: Permanent Magnet Synchronous Motor (AC) Rear: Induction Motor (AC)|
|8||Nissan Leaf||Synchronous Motor (AC)|
|9||Porsche Taycan||Dual Permanently Excited Synchronous Motors (AC)|
|10||Hyundai Kona Electric||Permanent-Magnet Synchronous Motor (AC)|
From this data, it is apparent that the world’s largest EV manufacturers are betting on AC motors to power their vehicles to robust sales and long-term success. But as evidenced by this list of the ten best-selling EVs, there are different types of AC motors corresponding to varying performance levels, and ultimately, vehicle cost.
Which is the Best Type of AC Motor?
Based on the current state of the electric car industry, EV manufacturers appear to be sold on AC motors as the most viable propulsion technology available now and for the foreseeable future. From mass-market EVs catering to everyday transportation needs to luxury electric cars that give world-renowned sports cars a good run for their money, AC motors cover the entire spectrum of driving needs.
Thus, the question then becomes, which type of AC motor is the best for electric cars? Two technologies appear to have the leg up on the others, and there are some big-name manufacturers associated with them, including the preeminent brand in electric cars.
Induction AC Motors
The fact that the electric car that put Tesla on the map, its flagship Model S, uses an induction AC motor says it all. Since its introduction, the Model S has long been considered the gold standard in high-end electric cars. Its unique combination of key performance attributes includes:
The induction AC motor utilized by the Model S is also found in Tesla’s newer, and thus far, wildly popular, Model Y. And dual induction motors are also used by the Audi e-tron. The main advantages of an induction AC motor from a manufacturer’s perspective are:
- Straightforward design and construction
- Manageable production costs
- Easier maintenance with fewer parts to replace
- Greater reliability
- No exposure to raw material shortages and price fluctuations (e.g., imported rare earth magnets)
From a driver’s perspective, induction motors excel in the torque department, meaning that they can accelerate quickly and give most traditional sports cars with internal combustion engines a good run for their money. Case in point, here are some performance specs for the current Tesla Model S that will appeal to any driving enthusiast:
- 0-60 miles per hour: 1.99 seconds
- Top speed: 200 miles per hour
- Peak power: 1,020 horsepower
The slight drawbacks of induction motors are the loss of efficiency at higher speeds and the tremendous amount of cooling they require to avoid overheating.
Permanent Magnet AC Motors
Of the ten best-selling electric cars in the world today, more than half utilize permanent magnet (PM) technology in their AC motors. The driving force behind this move is to take advantage of the PM motors’ greater efficiency, which translates to greater range for the vehicles that use them. (This despite lingering concerns about the availability of the rare-earth metals required to make them.)
This is a particularly appealing aspect for drivers who care more about their daily commute than how fast they can get from zero to 60. This is why Tesla bucked popular trends and caused quite a stir by incorporating a PM motor into its most affordable and overall best-selling Model 3. In fact, Tesla has gone even further by incorporating PM motors into its other models, most notably the S and the Y.
Dual Motor Electric Cars
One trend that likely is likely here to stay is the use of dual motors in electric cars. Essentially, by placing a motor on each axle, manufacturers can transform their EVs into all-wheel-drive vehicles. Not only does traction control improve, but torque and efficiency as well.
Take, for instance, the Dual Motor Model S from Tesla, which has a PM motor mounted on the front axle and an induction motor on the rear. As aptly described by Elon Musk, “one is optimized for power, and one for range,” referring to the tremendous torque produced by the induction motor at low speeds and the cruising speed efficiency provided by the PM motor.
As global green initiatives evolve from policy to reality, manufacturers are investing heavily in technologies that align with clean and sustainable energy ideals. Not too long ago, electric cars were more of a novelty than a legitimate mode of transportation. Today, EVs represent the path forward, and AC motors will keep them moving along at a brisk pace.