Electrical System

Chopper Del Sol was a great step forward in the electrical system that is crucial to any high performance solar racer. Valkyrie has many of the same design improvements that Chopper had; a huge emphasis was placed on efficiency, as well as better driver integration with the car. Valkyrie uses less power than a hair dryer, but can cruise at highway speeds using it’s advanced mono-crystalline silicon array.

Solar Array & MPPTs:

The 6 square meter array is made up of 21% efficient monocrystalline silicon cells. The power coming off the array is controlled by six custom-designed 98% efficient maximum power point trackers (MPPTs), for an estimated output of 1200 W. These MPPT modules act as an interface between the battery pack and the solar array, which ensure the cells are operating at their peak power.

Battery Pack:

Valkyrie‘s pack will be constructed from roughly 429 Lithium Ion cells, with a capacity of around 41 AHr. The cells are spot-welded into two half-packs, which are packed in electrically insulating kevlar for structural integrity and safety. The battery pack contains an active protection system that monitors the voltage and temperature of the cells, and has safeguards to protect against damage.

Chopper’s pack is constructed from 434 Lithium Ion cells, and has a capacity of 43 AHr. Thanks to our generous sponsors, including Panasonic, SEVT recently constructed its most energy-dense battery pack yet, one of the highlights of the electrical system. The battery pack monitors voltage and temperature of 600 cells, and has safeguards to protect against damage.

Communication:

A CAN network provides the team and the drivers with a constant data flow about the status of the battery pack and the solar array, allowing the team to optimize their speed in real-time.

Motor:

The drive behind Valkyrie is it’s brand new Mitsuba hub motor, which is much lighter than it’s predecessor. Hub motors are high efficiency due to their direct drive, and are specifically tailored to high efficiency vehicles such as solar racers. The motor has also been equipped with regenerative braking, allowing for further charging of the battery pack. Slowly sipping on its battery, Valkyrie can cruises for two hundred miles without recharging. Paired with the solar array, Valkyrie will be able to cruise under full sunshine almost indefinitely.

Rounding out Chopper del Sol‘s electrical system is the NGM motor, a high efficiency direct-drive motor, specifically tailored to high efficiency vehicles such as solar raycers. The motor has also been equipped with regenerative braking, allowing for further charging of the battery pack. Slowly sipping on its battery, Chopper cruises for two hundred miles without recharging. Paired with the solar array, Chopper can cruise under full sunshine almost indefinitely.

 

If you are interested in learning more about the electrical systems, please contact us at gosolar@mit.edu.