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Electric Motors FAQ

How does an electric motor behave differently from a combustion engine?

The power bands and torques of each of these engines are entirely different. While the power and torque of an internal combustion engine increase with RPM until they top out, in an electric motor maximum torque is delivered from almost zero revolutions and decreases as it reaches the highest RPM. In practice, this means that an electric car’s greatest traction is at the start, making it relatively dynamic. In addition, an electric motor’s very wide operating RPM range means that it doesn’t need a multi-speed transmission with a clutch, so your average electric car can get by with a single gear – or a reduction drive – from standstill to top speed.

How is consumption measured?

In electric cars, consumption indicates the energy consumed in kilowatt-hours per 100 kilometres of travel (kWh/100 km). As in conventional cars, the instrument cluster displays information on both the instantaneous and average consumption. On top of this, it also lets you know the amount of recovered energy sent back to the batteries.

How about the servicing and life of electric motors?

Since the main, and in fact the only, moving part of an electric motor is the rotor, servicing requirements are minimal in comparison to a combustion engine. There is no need for any oil changes or fuel and air filter replacement. These tend to be high-revving machines, so they need to be well designed (especially the bearings), but, in general, electric drive requires less maintenance than a conventional engine.

Is there a difference between the electric motors in plug-in hybrids and in pure electric cars?

Yes. In the design of a purely electric car, it is assumed that there will be no other type of drive in the car, so this doesn’t need to be taken into account. Consequently, the motor can be optimally primed for the required torque and power, RPM, and vehicle options.

The hybrid engine design, on the other hand, must also take into account the characteristics of the internal combustion engine that is to partner the electric motor, focusing on mechanical connection possibilities, operating temperatures, RPM, and the power band. The drive control system is also more complex. The car must be able to move purely electrically, with a combustion engine, or in combined mode, and always with optimal energy use.