Why Do Most Electric Cars Use AC Motors


The world is fast-changing, and our cars are changing with it. We went from rodeo cowboy to old steam engine, then fossil fuel cars, and now to electric cars. In this day and age, 99% of things we use, are powered by electricity.

There is no perfect time to make the switch from the internal combustion engine to the electric car than now because governments are subsidizing electric car technologies.

But the main reason why there are relatively more electric car owners is not because of a dire need to save the planet, but the driving range is higher than it was in the recent past.

This extended range that is provided by some present electric cars has increased the probability of an overheating battery.

Why do most electric cars use AC motors? The main reason why most electric car makers use AC motors in an electric car is that it can travel long distances without overheating.  This is appealing to the average consumer that wishes to reduce the frequency of charges required for an electric car.

But is that the only reason why most electric car makers opt for AC motors? Let’s find out.

Do electric cars use AC motors?

Electric cars of the past suffered from the lack of an efficient electric motor limiting the vehicles range to 10 miles per hour (ca. 16 kilometers per hour) also plus poor battery technology. Nevertheless, since the invention of Nikolai Tesla, which uses the AC induction motor, automakers now have a newly rekindled interest in manufacturing electric cars.

With the whole energy crisis going on in the eastern world, this has resulted in an ever-growing cost of gas, forcing consumers to find an alternative, with the help of AC motors found in most electric cars such as the Tesla, BMW I3, Chevrolet Bolt, etc.

In fact, Tesla has been rumored to use an AC induction motor in all its models with the exception of a few cases.  The root of Tesla is AC propulsion, a motor that allows AC induction traction.

The company made the first electric car in the United States called Tzero.  It had the highest range ever seen on an electric car at that time, which was  200 miles (ca. 321,869 m). Elon Musk viewed their prototype called the Tzero and was very impressed.

Why did electric car manufacturers switch from dc to ac motors?

Before the recent adaptation of AC motors, electric cars used DC motors and a few still use DC motors in their electric models. DC motors were mostly used in small gadgets like a CD player, windshield wiper, power side mirrors, etc.

The problem with DC motors is:

  • High maintenance cost due to the presence of a commutator and a brush
  • High cost
  • Heat buildup due to overdriving

Electric car makers are looking for ways to make a profit, and to cut costs as much as possible and still give the customers what they want. DC motors, even the brushless DC motors, have to have magnets in them. This magnet requirement was increasing the cost and complexity to a level much higher than that of AC induction motors. As a result, most carmakers went for the AC type.

Does Tesla use ac or dc motor?

Tesla is the biggest maker of electric cars in the United States, reaching sales of above 100,000 units yearly and a 12% market share in the plugin car section. The company is now worth about 70 billion dollars.

If you have been reading this post keenly, you will now know that the first motor used in a tesla was an AC motor.  In fact, it was the Tzero that gave planted the seed that electric cars like the Tzero made with AC motors could go very long-range. Even as far as 250 miles (402.34 kilometers) on one charge.

The main reason why Tesla uses the AC induction motor is that the first feasible prototype the Tzero had induction motors. This doesn’t mean that Tesla motors only use induction motors. One of the company’s best-selling cars, the Tesla Model 3 has a DC motor.

Which motor is best for electric cars?

Electric car automakers have the duty of being able to predict their customers’ desires.  Plenty of automakers in the United States are making electric cars that appeal to millennials. This segment of the population is younger meaning that they have not peaked financially.

In order for electric car makers to sell to this group of people, carmakers needed to cut the price of their electric cars.

Which electric motors are best for electric cars? The real answer is subjective. It is based on the targeted customers the car automaker wants to reach out to.

If a particular electric car automaker wants to capture the generation Z market share, he will have to sell not so expensive cars. To reduce the cost of motors, it’s best to go with brushless DC motors, even though DC motors are expensive. The brushless DC motors are far cheaper to make than the AC induction motor plus it functions as a sister to the AC motors because of similar modes of operation.

But if the automakers want to capture an audience that loves high-performance muscle cars, then AC motors will get the job done because of their ability to handle rougher terrain and accelerate much easily.

The icing on the cake is that AC electric motors last much longer than DC.

You are now starting to get a feel of why electric car makers opt for AC electric motors, but let us dig deeper a little.

Why ac electric motors are better than dc

A report on electric ac motor market analysis has estimated that AC motors sales will reach 166.5 billion dollars by 2026 at an 8.8% annual growth rate, with well-known companies like Siemens, Rockwell automation, Franklin electric co, etc.  This recent trend has shown how confidently these large companies are investing in electric AC motors.

Generally, AC electric motors are powered by an alternating current. Hence they are brushless. An AC Motor achieves high torque with the help of a controller called a variable frequency drive (VFD). This controller is used to vary the speed and power generated.

Furthermore, AC electric motors can handle high voltages up to 240 volts, hence this reduces the size and amount of wires needed.

Another aspect where AC electric motors shine through is their ability to function as a generator when the driver steps on the brake. This phenomenon is called regenerative braking. It is a special feature of AC electric motors. For instance, Tesla cars are estimated to return as much as 60 kW of electricity to the battery pack during braking.

To learn more about regenerative braking visit engineering.com

But DC motors are not left behind since we mentioned that they are cheaper to build than AC. However, in the long run,  they require more maintenance. Nevertheless, the initial lower price tag works to the advantage of some electric car makers who want to provide a decent not so expensive electric car at an affordable price to capture the generation Z market share.

My conclusion

There is still no knock out win between the AC induction motor and the DC brushless motor, my conclusion is that brushless DC motors will still be featured in hybrid car models and the entry-level electric car model.  On the other hand, AC induction motors will continue to dominate the high-performance electric motors segment.

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