Thursday, December 24, 2009
The Xof1 Solar Car has an amazing electric motor. The motor is an axial flux brushless DC motor that can produce 7 hp, yet weighs less then 40 pounds. A typical industrial 5 hp electric motor weighs 200 pounds. In the picture you can see the stamped flat plat copper coils and further inside the iron laminations of the slotted stator. The copper is covered in a varnish insulation which is why everything looks goopy. This motor is made by New Generation Motors and is specifically designed for solar powered cars.
Tuesday, December 22, 2009
This is a picture of an early test assembly of the electronics compartment. The big black box is the motor controller. There is also a telemetry radio, the telemetry computer, various patch panels, and a Vicor DC DC converter.
There were probably 100 of these test assemblies. The final system did not include the telemetry computer or radio.
The (scary looking) little brown board in the upper right is a board with calibrated shunts for doing current monitoring.
Observe the tape on the one side of the box. "NO METAL TOOLS....". Dropping a metal tool in this box with the power on would be a very expensive and dangerous light show. When working on an electric vehicle its good practice to completely cover metal tools with fusion tape to ensure they cant short various things.
Saturday, December 19, 2009
The Xof1 Solar Car array getting encapsulated in 2004. To make the solar array durable, it is coated in an optically clear resin. Many coats are required to make something like 1/16th of an inch coating. The resin got a bit thick part way through the day and we had to go find a jug of xylene on a Saturday. Some local paint shop had an ancient can in the back room.
Thursday, December 17, 2009
The solar car's array needs to be encapsulated in a near optically clear resin coating. Here the car is at a body shop in the beaches one saturday morning. Marcelo and an auto body technician are masking the array. This was a nail biting day since all the months invested in building the array and wiring all 900 cells together will be entombed in plastic, and will hopefully work afterwards.
Monday, December 14, 2009
Sunday, December 13, 2009
In this photo the solar array build is partially complete. The cells are like very thin glass and have to placed precisely on the super sticky taped array surface. Its a one way operation....if the cell is not placed precisely the cell and the tape underneath has to be removed and redone. All together the array required about 900 cells.
Friday, December 11, 2009
Thursday, December 10, 2009
Here are a two strings of solar cells prepared for checking fit and placement on the array. These cells were laser cut into rectangles and then hand soldered together, a very taxing process necessary to maximize array density.
Wednesday, December 9, 2009
Here is a pic of the car in mid-2004. The Xof1 car is built from high tech fiberglass and low tech expanded polyurethane. Here the car's array has been taped with a medium tech two sided tape to which the photovoltaic cells will be 'stuck' to the car. This tape was very hard to come by since most of its production was being used in support of the second Gulf War. It was very sticky and provided about 1/16th inch of shock absorbing rubbery material.
Here is an early electrical experiment for the Xof1 car. This is a PIC microcontroller driven lighting harness. One of the boards on the right side is a mini version of the lighting with turn signals, headlamps, and brake lights. The other board is a mini set of switches as would be on the car. I think JV built and programmed this whole circuit.
I participated in the building of the Xof1 Solar Car which now holds many records for overall distance, longest distance in one day, and notable accomplishments like the first solar car on ice, first solar car in the arctic. I have been asked to post pictures that I have from the project since many of the original photos that Marcelo took during the build were lost in a burglary. Anyway, this is a scan of a PCB that was made early on. Xof1's batteries were giant sized lithium ion polymer batteries from Kokam which theoretically needed a battery management system to control charge and discharge and to keep a watch on temperature. Temperature especially since the last thing you want is to be enclosed in a tiny space with a lithium battery fire. This PCB was either designed by Mario Bilusic or maybe John Visosky, and probably made my John. The design of an effective BMS is very difficult. This board was an early experiment and looks nothing at all like later versions of the BMS since many requirements were discovered over the two or three years that the BMS was worked on. The approach in use for this board looks like a PIC microcontroller running some MOSFETs using PWM, based in input from a current sensor to control 7 batter packs... I understand that in the end Marcelo operated xof1 well within the batteries limitations and that the batteries performed better than expected and for longer than expected.