Study into energy efficiency of the drive of electric vehicles with an independent power supply depending on the configuration of the power source

The electric vehicle with an independent power supply is the object of this research. At present, such vehicles are becoming more popular in the automobile market, pushing out their rivals with internal combustion engines, owing to their superior energy efficiency. The advantage over the internal combustion engine vehicles being obvious, the efficiency of electric vehicles is still considerably low in comparison to other electric devices. The problem that causes these limitations lies in the power supply – li-ion accumulator – which has high impedance. In order to solve this disadvantage, the system with an ultracapacitor battery connected in parallel to the accumulator was considered using an example of the electric scooter drive with a squirrel-caged induction motor. Ultracapacitors have significantly lesser impedance than accumulators, thus they carry with themselves most of instant load during acceleration and braking when a power source supplies the highest currents. Our study has shown that this configuration improves energy efficiency of the electric vehicles. Moreover, there is an optimal amount of ultracapacitor capacitance for achieving the best efficiency (the lowest energy consumption). This follows from the fact that an ultracapacitor battery is a rather heavy object; a significant increase in its capacitance leads to the increased vehicle weight and thus enhances energy consumption. An additional modernized system of supply was considered at which ultracapacitor’s charging is accelerated during vehicle stops. Such a system has made it possible to improve the results and decrease energy consumption even larger. Compared to previous studies, this research demonstrates the importance of correct choice of ultracapacitor capacitance and supply distribution system. The existence of the optimum point has been proven; the difference of energy consumption at this point has been demonstrated in numbers.