Further Improvement of Sunspec 4

Motor Configuration

The main objective to reconfigure the motor is to reduce power consumption by reducing to single motor drive. We made a few calculations to see whather two wheel drive or one wheel drive is better for Suncpec car performance.

Below are the details:

SunSPEC 3 is using 2 1KW Mitsuba motor and the weight of the car is about 380 kg with passenger.

SunSPEC 4 is using 2 2KW Mitsuba motor and weight of the car is about 400 kg with passenger.

If 2 1KW motor could drive 380kg, hence many ideas for SunSPEC 5 such as:

Should we implement Single 2KW motor either one side of the wheel such as the car from Kogakuin University
Or 2 1KW motor like SunSPEC 3

Many ideas came about as we want to the motor to consume as minimal energy from the battery. SunSPEC 3 perform well during the 2013 race. No terrain issues.

Over at Australia, we met many teams and discuss over their motor strategy. Our neighbor, Univerisity of Kogaguin. Our team was curious about their strategy whereby they only use a single Mitsuba 2KW motor on the left wheel. The weight of their is slightly higher than us but single driver about 350 Kg and they completed 3022 KM.

Then we compare with SunSPEC 3 weight which is slightly lighter then SunSPEC 4. But SunSPEC 3 did not complete the race due to weight issues and insufficient battery capacity. If we were to use single 2KW motor, calculations are below,

Motor : (2KW/96V) X 45hr = 937.5 Ah

If using 34S36P to run single motor,

5184(Battery)/937.5(Motor) = 5.5 Days

Hence even without solar panels, the motor can run for 5.5 days. Hence single motor can also reduce the weight of the car and uses lesser power. We believe with solar panels, the car can even travel for 6 days.

Control panel rearrangement

SunSPEC 4 control panel was place in-between the driver and the passenger. The control panel allow the driver to control the car via switches and Circuit Breakers. It consists of Circuit Breaker of Solar panels and Motor, Switches for motor and knob for cruise and regen braking.

During the race, we realize that it is dangerous for the driver hand to be off from the steering wheel. Currently, the cruise and regen knob were placed on the control panel. Ideas from commercial vehicle, even the volume button and cruise mode was commonly found on the steering wheel to allow the driver to place 2 hands on the steering wheel as shown in figure below.

By rearranging the knobs to the steering wheel, driver can now use cruise and regen mode using their fingers to adjust and this allow the driver to place both hands on the steering wheel for safety purpose.

Implementing dashboard

SunSPEC 4 is leaving out a proper dashboard for the driver to read information. Telemetry readings is dangling far away near the control panel; speedometer is place on the steering wheel. SunSPEC 4 display is messy hence by implementing the dashboard right in front of the driver allow all the display and information the driver needs. Figure below showing solar team of Bochum dashboard.

Wiring

While wiring SunSPEC 4, the team felt that the car is not planned for wiring as there no proper tunnels and proper routes for the wire to run.

During the design stage of the car, maybe the wiring can be planned and route together with the car design during this stage. This will help the wiring to be neater as wiring is being implemented with the car design eg, tunnel for wires to run without being expose.

We hope with this, wiring blueprint produce will make wiring to be neater and easier to rectify.

Conclusion

SunSpec4 performance in the race is considered as good. However, we are still looking for further improvements to our car in the upcoming years. After much discussion, we might consider to implement a single motor on the left wheel to reduce car weight and consume lesser energies from batteries.

For control panel parts, we might change the cruise mode put onto the steering wheel so that the driver easy access on it while driving. All the circuit breakers also might be replaced by relays to make the inside car body looks more tidy. Finally, wiring system in SunSpec4 is not neat even though we have used the wire wrappers to wrap all the messy wires.

Hence, we decide to use Zuken blueprint to implement wirings during the conceive design stage of SunSpec 5 to make wiring as a consideration. Overall, with these entire good ideas implemented on SunSpec 5, we believe we can achieve a better performance in the upcoming years of World Solar Challenge.