Technology overview: Unlike an internal combustion engine that is mainly operated by an engine, the powertrain of an electric vehicle is a system run by an electric motor with a decelerator using battery.
The powertrain of an electric vehicle consists of a driving mechanism that directly uses a motor’s torque to run wheels. Since it only uses battery as a power source, it is very important to develop high power output and high performance of traction motor and decelerator, and weight reduction technology. Once these are accomplished, it is possible to extend the vehicle miles traveled. In advanced countries, permanent magnet synchronous motor made of rare earth materials is generally used to achieve high performance and high power density. An acquirement of cost-competitiveness has been greatly attracted in automotive industry as the cost of rare earth materials has been on the rise.
In addition, it is very important to maximize the vehicle miles traveled, reduce the material cost of electric components as well as weight, and improve loadability while maintaining the same amount of battery capacity. In this project, a powertrain mass production technology of weight reducing single- stage decelerator and permanent magnet synchronous motor have been developed to reduce weight and maximize efficiency.
Industrialization: A traction motor, one of the core components of powertrain for electric vehicles and single-stage decelerator have been developed in this project and applied to the mass-production of Soul EV, a C-segment electric vehicle. Moreover, obtaining high performance (vehicle miles traveled), low noise and parking safety are enormously essential for electric vehicles.
In order to maximize productivity, the 80kW traction motor for C-segment electric vehicles developed in this project employs the magnet assembly step-skew technology and the pole pitch angle optimization technology for a reduction of torque ripple which affects the noise and vibration of an electric vehicle.
High performance cooling system to increase the heat dissipation area of cooling channel is crucial for maximizing performance of motor, thus the pin-shaped water cooling channel housing has been employed.
A decelerator is a device that delivers a motor torque to the wheels, and we have developed a decelerating device that can increase motor torque by about 8 times while maintaining the rotational speed.
In this project, a gear layout design of 80kW electric vehicle’s decelerator has been optimized for high performance. Also, transmission efficiency reached the goal by using low viscosity oil and minimizing friction loss. Parking performance and durability specification were acquired through a vehicle test. In addition, by conducting NVH module analysis, support stiffness design optimization and stator tooth design (tooth design decision test), a competitive single-stage decelerator with good NVH performance has been developed.
Problem-solving in industrialization: To increase driving motor’s power density (kW/kg), weight reduction design and reluctance torque design optimization have been applied in this project. Furthermore, for a production cost reduction of permanent magnets, GBD (Grain Boundary Diffusion) technology has been employed to minimize the amount of Dysprosium (Dy) by more than 40%, a rare earth material.
Technology developer: Hyundai Mobis Co., Ltd. / +82-31-288-5103 / www.mobis.co.kr
Decelerator / Driving motor / Motor decelerator assy
korean-machinery.com | Blog Magazine of korean-machinery, brands and Goods