Tech@Lunch: Electric Gears and their Impact on Future EVs

The topic of this session from the Tech@Lunch series is 'Electric Gears and their Impact on Future EVs'. The key drivers for electric motor development for electric vehicles nowadays are compactness, power density, energy efficiency and cost. That is the reason why current electric vehicles often use permanent magnet motors: they offer this desired high power density and excellent efficiency. However, permanent magnet motors have the disadvantage that their speed is limited by the available battery voltage. As the addition of a mechanical gearbox has a negative impact on cost and efficiency, we propose to transform a standard electric motor drive into an electric gear. The concept of such an e-gear is based on the fact that the efficient operating range of an electric motor alters when you change its winding connection. By adding a switching unit to the standard motor drive, we can adapt this winding connection online, while the motor is running. The efficient speed range is extended in this way, without the need for a mechanical gearbox.

In this Tech@Lunch session, we will delve deeper into the e-gear concept. We will discuss how we can alter a standard electric motor into an e-gear, without changing its original rated power or maximum torque. Different types of switching units and windings connections for a variety of torque and speed ranges will be covered. Afterwards, we will take a closer look at our e-gear demonstrator. This demonstrator allows to double the speed range of the original drive by means of a cheap and efficient switching unit. Its shift time is competitive with the gearbox of a Lamborghini Aventador.