Reverse Engineering of an Electric Vehicle Motor and Tests of a Charging Station

Nowadays the attention given to the environment is growing up considerably. With increasing concern over the environment and stringent emissions regulations, the electric vehicle has been investigated as an alternative form of transport. There are many advantages but even many disadvantages of an electric vehicle.

The first advantage is that no gasoline is required, there is no combustion and so there is no pollution associated with internal engine. Nevertheless, they still have environmental costs. The electricity used to recharge the batteries has to come from somewhere, and now, most electricity is generated by burning fossil fuels. Of course, this produces pollution. Imagining a future generation of electricity, for the most part produced by renewable sources, there will be no pollution generated by energy production. An electric vehicle is really silent, the motor makes almost no noise. To avoid accidents, the car manufacturers have,even, to install a device that makes a little noise for pedestrian safety.

A big disadvantage of electric battery vehicles is the time required to recharge the batteries. This process can take up to 15-20hours. Even the autonomy is one of the major disadvantages, because with a common 24kWh battery package it is no possible to travel for more than 200km. The last but not the least disadvantage is the price. The purchasing cost of an electric vehicle is higher than the cost of a “normal” engine vehicle. This is mainly due to the battery package and to the low volume of production.

The electric vehicles have already achieved excellent performance skills, in terms of speed and acceleration, due to the electric motor. An electric motor is far more efficient than an internal combustion engine (90% instead of 40%), with a smaller footprint than a combustion engine. Despite these really good performances , there is still much work to do to be able to make an electric vehicle comparable to, or better than, a regular vehicle with combustion engine. However, the electric vehicle suffers from relatively short range and long charging times. Therefore it is fundamental to design more efficient traction motors for the electric vehicles and to improve the charging station to have a reasonable improvement of charging times.

The aim of this work is to analyse the electric vehicle motor and the charging station system. The thesis describes Electromagnetic and Thermal simulations of the Nissan Leaf motor in different operating conditions trying to give an useful help to the improvement of the motor. Afterwards the simulations are compared with the real thermal results. Even a study of the charging times, of the electrical parameters during the recharge is carried out.

The drive motor used on the Nissan LEAF is an interior permanent magnet synchronous motor (IPM) with an original design adapted to the ways in which EVs are driven. Compact in size, it delivers high power and efficiency to support the quick response characteristic of EVs. Generating maximum torque of 280 Nm and maximum power of 80 kW, the motor provides the high levels of performance required of EV drive motors and attains a top speed of 10,390 rpm. As part of its basic structure, a water cooling system has been adopted to facilitate higher continuous power output and a resolver is used as the rotary position sensor to ensure high response.

This thesis is divided into five chapters:
1. The first chapter are presents the process for the creation of the Nissan Leaf motor model and the results of the ElectroMagnetic and Thermal simulations.
The softwares used for these simulations are Motor-CAD and Motor-LAB, but even a results comparison is conducted using Ansys Maxwell. This part has been performed in England at the Motor Design Limited Headquarters.
2. The second chapter concerns experimental tests. Few thermal tests are carried out to compare the simulations results to the experimental tests. In the second part of the chapter few autonomy and performance tests are performed. This part of the thesis has been developed at the Loccioni Group.
3. The third chapter takes under examination the Charging Station Systems and the way they recharge the EVs. The charging stations analyzed are two: the Enel Pole Station 2G and the Schneider EVLink EVF1S. Even this part of the thesis has been performed at the Loccioni Group.
4. The fourth chapter shows a cost analysis of an electric vehicle and of the energy required for the recharge.
5. In the last chapter few innovative systems for the electric vehicle recharge are presented with a system using the solar energy to recharge batteries and another called Leaf to Home.