The first battery-powered electric vehicles could be seen roaming the streets as early as the 19th century, before the combustion engine was invented. The successor technology only prevailed in the 20th century, and one of the primary reasons for that was that combustion engines enabled significantly greater ranges of speeds. The basic operating principle of an electric motor hasn’t changed since the technology was invented in the 19th century: An engine consists of a moving element (the rotor), and a stationary element (the stator), which is permanently attached to the housing. When a current flows through the motor, the two elements have different magnetic fields, which repel each other – causing the rotor and the rotor shaft to move.
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Synchronous Three-Phase Engines Successful
The development of electric motors for cars continues to advance, and an increasing number of manufacturers rely on in-house developments to try and establish their own expertise. As a rule, three-phase motors have become the established technology for cars. They are significantly lighter and more compact than DC motors and use what’s known as three-phase alternating current – familiar to many users from their homes.
For electric cars, it is important to distinguish between synchronous and asynchronous three-phase motors. The latter have a small delay between the generation of the magnetic field in the rotor and that in the stator. You could say that the rotor is following the frequency of the magnetic field asynchronously. In synchronous electric motors on the other hand, the frequencies of the rotor and the stator are aligned – a seemingly small difference, that makes a major difference: Synchronous three-phase motors have better efficiency in operation, which is why nearly all manufacturers rely on synchronous three-phase motors. These engines include a rotor that is made from a magnetic material. Experts refer to this type as a permanently excited synchronous motor.
Where is the Electric Motor?
The final question is where in a car the electric motor is located. Most of the completely electric vehicles have a central motor in the front, which is permanently connected to the drive axle. The design is similar to combustion engine cars. However, it is also conceivable that future 4WD vehicles might have one motor on the front and rear axle each, controlled individually depending on the situation. Another much-discussed variation is the hub drive. In a hub drive, four (smaller) motors are installed directly behind the wheels. This solution is relatively lightweight because the cars don’t need a power train with a gearbox and drive shafts. On the downside, this increases the overall mass of a vehicle: The wheels become rather heavy, which results in performance loss if the road isn’t perfectly level.
The question of engines will only play a small role in the rate at which entirely electric or plug-in hybrid vehicles become established in the market. In general, electric motors have a simpler design than comparable combustion engines, making them more cost-effective to maintain. One of the main drawbacks, however, of the current electric vehicles is their large price tag, which is primarily caused by power storage requirements.