1.1 Background and Significance of Selected Topics

In recent years,China's automobile industry has developed rapidly, according to statisticaldata, to 2016, China's auto output is expectedto exceed 30 million. Car ownership in31 cities across the country exceeded 1 million in 2013. However, along with the rapid development of theautomobile industry, the domestic environment has also suffered tremendousdamage. In recent years, the haze phenomenon in China has been particularlyserious. One of the main causes of theseenvironmental problems is that most of the cars still rely on traditionalinternal combustion engine cars that burn fossil fuels. Due to problems such as environmental pollution, noise, and energyshortage caused by traditional internal combustion engine vehicles, peoplebegan to urgently need to find a suitable energy source to replace fossilenergy. Electric vehicles gradually shift theirfocus to the field of electric vehicles with the advantages of low emissions,low noise, etc. At present, theworld's major auto-producing countries regard electric vehicles as the futuredevelopment direction, and the electric vehicle industry has developed rapidly.Currently, wheel hub drive technology is one of the most promising directionsin the field of electric vehicles.

Actually, American Robert applied for an Americaninvention patent integrating the brake system, electric motor and drive trainin the hub as early as the 1950s. It is the earliest electric wheel prototype.The device was later applied to large mining dump truck. In recent years, dueto the rapid development of science and technology and manufacturing industry,the performance of automotive motors has been greatly improved. Experts andscholars at home and abroad have gradually focused on wheel hub motor drivetechnology, and wheel hub motor drive technology is attracting the attention ofthe world.

1.2 Research Statusanalysis outside the country

The applicationof wheel hub motors in automobiles can be traced back to the 50s of the lastcentury. The American Robert applied for an invention patent, which integratesthe brake system, the drive train, and the motor into the wheel hub, and is theearliest form of electric wheel. In1968, General Electric of the United States applied the electric wheel deviceto a large mining dump truck.

In 2011, Professor Qing Shuihao team developed a new electric vehicle"SIM-LEI" driven by a hub motor. Thebody of the electric vehicle is lightweight and equipped with quick chargingequipment. It can be filled within 30 minutes and can travel 338 kilometers afterbeing fully charged.

In 2013, the French Peugeot-CitroenAutomobile Company developed a four-wheel hub motor-driven electric car quark. The electric vehicle adopts an air-coolingmethod and a hydrogen fuel cell. Four wheel hub motors are driven by theelectric energy discharged from the fuel cell. The vehicle requires a vehiclespeed of 48km/h to take 6.5 seconds.

In 2013, Ford Motor Company of the UnitedStates showed off its development of an eWheelDrive in-wheel motor-drivenelectric vehicle. The electric vehicle was developed on the basis of the FordFiesta model and used rear wheel drive of the hub motor.