Designing the Lightyear One: In-wheel motors

Wiebe Janssen — Powertrain Engineer

In the process of designing a car, choosing the right motor is very important. I would like to give a look into this process by explaining what we look for in motors and how we approach this search for the best possible match for the Lightyear One. 

Why using motors within the wheels rather than elsewhere

A very important reason to use in-wheel motors, is to optimize the Lightyear One for efficiency to make it a success as a commercial solar car. To do so we looked at existing innovations, as well as what direction we wanted to take the Lightyear One. In-wheel motors offer a solution. By elimination of the transmission we minimize needless energy loss. Moreover, the car becomes lighter, and a lighter car requires less energy.

We want to make owning a Lightyear One a true pleasure to use, also on the long runOne component of doing so is reducing the cost of ownership for the Lightyear One. By reducing the amount of maintenance needed, the car becomes cheaper over it’s lifecycle. The best way to achieve this is by keeping the systems as simple as possible. In-wheel motors drastically reduce the amount of moving parts in the car and with that the need for maintenance.

Another convenience of using in-wheel motors is the extra space. By using small distributed motors a lot of space is freed up within the car.

Visual representation of the extra space available when having an in-wheel motor

Last but not least, indepence is a core goal for our car. We want the car to be independent from the grid but also the road network the user choose to drive. To enable driving off-road you need individual and precise control over each wheel individually. The complete drivetrain will allow for this.

All these factors combined made in-wheel motors the ideal choice to make Lightyear One a success as the first long-range solar car.

The process of picking the perfect motor for the Lightyear One

You cannot just arbitrarily pick one motor configuration or design, place it in all four wheels and be done with it. We have to carefully go through the process from requirement definition, system design and concept evaluation. Next to that, partnerships throughout designs, development, manufacturing, prototyping and testing have to be established. We want to find the best possible match.

The right configuration will lead to the desired performance. This technology has an enormous potential. Because we are developing a novel powertrain platform we are not just creating new possibilities for the Lightyear One, but also for the models to come. The choices we make in this stage will affect the ones for  the years to come. As such we have stringent requirements for efficiency, weight and torque.

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