Emissions-free vehicles are the future of transportation. Manufacturers strive to improve the characteristics of electrical vehicles. Two of the electrical vehicle problems are the costs of batteries and the time to recharge them.
A proposal to solve part of this problem is to develop an Aerodynamic Electric Solar Bus (AESB). This bus reduces batteries consumption by producing one part of its energy from solar radiation and regenerative braking; furthermore, the AESB increases it performance because of its low drag coefficient. The AESB allows to achieve an autonomy up to 700 km with 2000 kg payload to 80 km/h with only 200 kWh battery charge.
The AESB will not have a gearbox nor mechanical differential transmission in the power train. It will use 4 independent brushless motors of 70kW (4 x 94 Hp) controlled by Digital Signal Processors (DSPs) and SiC MOSFETs to increase the energy efficiency and to reduce the size of power electronics modules. If the AESB is accelerating or deaccelerating, the four motors will start. When constant speed is reached, torque will be reduced, and the two rear motors will turn off to improve motor efficiencies.
Simulation results show that a set of 30 m2 solar cells of 25% efficiency on the AESB roof and the regenerative braking will give extra energy that increases travel distances by 20% to 70% for intercity and urban displacements. The characteristics obtained from the AESB through a simulation, using the NEDC test (New European Drive Cycle), shows energy increasing 25.96% with solar cells and 37.29% with regenerative braking to achieve a performance of 4.43 km/kWh.
The heating produced by motors and any irradiation that is not utilized by solar cells can be used by the acclimatizer to obtain cold or heat in an efficient way. For better performance and comfort of the AESB, there will be other elements that will be used: Circuits of Maximum Power Point Tracking (MPPT) for solar cell groups, high efficacy LEDs, CAN networks, anti-collision detectors, security sensors, customizable spaces, electric servo direction, rearview cameras, security cameras, comfortable seats with presence detectors, individual screen for each passenger, wheelchair support, restroom, bed for a bus driver, service area, wireless wheel pressure sensors, Wi Fi and wide range of options.
The AESB would be used in any location, but it will be more effective where average solar irradiation is over 4 kWh/m2/day. The initial idea would be to develop and manufacture the AESBs in Mexico because of the low-cost labor, infrastructure for vehicle factories and the high solar irradiation. The AESB operating costs will be low because it is virtually a maintenance free vehicle and uses less energy to recharge batteries than other electric buses.
The prototypes will be manufactured and programmed by a team of engineers and technicians. First units will be an adaption of traditional buses with this mentioned technology. Then, next units will have a low drag coefficient bodywork constructed with light materials for more autonomy.