Cars using electricity for some part of their motive power are becoming far more common, with more than 250,000 electric hybrid vehicles sold every year since 2007. Once confined to only a handful of major cities, electric vehicle charging stations are now found throughout the United States, with more than 14,000 operational from coast to coast.
The fundamental technologies that make electric cars possible have been around for years, but only recently have they come together to produce remarkably safe, fuel efficient vehicles with high range. Infrastructure struggled to catch up with the opportunity represented by these new cars, but now, they have a bright future ahead. For electrical engineers, it’s worth taking a close look at the significant features and components of an electric vehicle and how they address various challenges.
Let’s consider some of the most important parts of the electric car:
Although many people think of gas-electric hybrids when they think of electric cars, true BEVs – battery electric vehicles – are generating the most excitement. The batteries can be charged through the use of ordinary grid electricity at a specialized power station. Aside from conventional lithium ion battery technologies, there are at least four major battery technologies now represented: Solid state, aluminum ion, lithium sulfur, and metal-air. Although top ranges of 200 miles or more are now attainable, a range around 70-100 miles on a full charge is more typical.
The Motor Controller
The control system governs the complete operation of the electric vehicle and the distribution of its power at any given moment. It monitors and helps to regular all key performance indicators, including those from the vehicle’s operator, motor, battery, motor controller, accelerator pedal, and more. Equipped with a powerful microprocessor, it can limit or redirect current – either to improve the mechanical performance of the device or suit the operator’s driving style. Generally, more sophisticated controllers are capable of greater precision and thus, higher efficiency.
The Electric Engine
Electric engines can be structured to use either AC or DC current. AC motors tend to be less expensive and lighter than DC engines, reaching about 95% efficiency at full load compared to the 85%-95% attained by AC engines. AC engines are more common in other types of electrical devices and, due in large part to the reduced number of moving parts, tend to be suffer from less mechanical wear and tear. AC technology requires a more sophisticated controller, however.
With its capacity to enhance the range of an electric vehicle, regenerative braking has been adopted in virtually all hybrid and BEV models on the road today. Put simply, it allows for the extraction of energy from the braked components so it can be reused rather than wasted. When the operator applies the brake, the electric motor goes into reverse mode, allowing the motor itself to do most of the “braking” and thus prevent more kinetic energy from being lost. This contrasts conventional systems using brake pads, which generate friction at multiple levels to achieve breaking.
The Drive System
The drive system’s function is to transfer mechanical energy to the traction wheels, generating motion. An electric vehicle does not require anything resembling a conventional transmission – but there are several different internal configurations depending on the components in use. For example, a large electric motor may be coupled to the rear wheels using a differential housing. Some designs use multiple smaller motors that power each wheel individually.
Energy Efficiency and Environmental Impact
It should come as no surprise that environmental impact is one of the most persuasive arguments for the electric car. Research has indicated that even those all-electric vehicles charged using the dirtiest areas of the U.S. power grid still produce less pollution than gasoline-fueled cars. Electric vehicles reduce energy consumption in a number of ways, including by automatically turning the engine off while idle, which would not be efficient for conventional vehicles. Plus, users of these cars can save $1,000 or more annually compared to the cost of a gasoline-fueled vehicle.
The Future is Bright for the Electric Car
As people look for ways to meet their commuting needs with minimal environmental impact and cost, electric cars are sure to maintain their high profile in the modern automotive market. While the very first hybrid car was made in the 1800s, electric cars of any kind were not regarded seriously until the late 1960s. Consumer electric vehicles were not widely available until the turn of the last century and infrastructure for their use has appeared in only the last few years. In this context, the rapid growth of the electric vehicle is truly something amazing. Electrical engineers will be at the forefront of change as this exciting technology continues to be refined. In just a few decades, electric vehicles could become the dominant force on America’s roads.
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