What are Hub Motors?
Hazards of Overheating in Hub Motors
Hub motors generate heat when operating at high speed and braking. Because the hub motor is integrated within the hub, it has a poor heat dissipation environment. The compact space of the wheel makes it easier for the motor to overheat and makes it harder to effectively dissipate the heat.
Vehicle: High temperatures can affect the performance of the hub motor and, consequently, the overall performance of the vehicle.
Motor: Temperatures that exceed 140°C (248°F) can cause the permanent magnets to demagnetize, impacting the performance of the hub motors.
Tires: Moreover, installing the motor within the wheel can lead to in-wheel motors overheating. Coupled with the heat produced by wheel friction, it can cause damage to the tires.
Image Source: Ebikes
Solutions to Hub Motors’ Heat Dissipation Problems
Use new cooling materials, such as carbon nanotube heat dissipation materials or graphene composite materials, to enhance the cooling speed and heat dissipation performance.
Optimize the existing system. One method is to enlarge the area of the heat dissipation ribs to improve its heat dissipation areas. Alternatively, optimizing the arrangement of the heat dissipation ribs in line with the wind direction can also enhance the heat dissipation effect.
Learn from mid-drive motors. Embedding the magnet in the iron core allows it to divert the demagnetizing magnetic field and protect the permanent magnet. The transition from applying the magnets to the surfaces of rotors to inserting them into rotors.
Optimize the hub motor’s cooling scheme, such as using water to cool the motor-stator assembly and using air to cool the motor-rotor assembly.
Use devices to prevent demagnetization. The main heat source of the drive motor comes from the brakes. During the braking process, the heat produced by the friction also affects the drive motor. A silicon steel sheet in the brake disc can offer protection, effectively insulating the heat and reducing the thermal load on the drive motor.
Research and develop new wheel drive motors. Current wheel motor developers tend to only focus on the motors, paying no attention to the hubs. Making the hub in the shape of a fan could achieve a better cooling effect. So, a comprehensive design that includes both the hub and motor can further improve the cooling effect.
Image Source: UUmotor
Despite some existing challenges with hub motors, this new form of driving design has significant advantages. With the resolution of heat dissipation and other problems, the performance of hub motors will continue to improve, leading to their wider use in electric vehicles and motorcycles.
At Tengye, we’re thrilled to be early participants in your new projects. Our passion for magnets extends from material selection and design optimization to providing magnetic solutions. We hope to bring our knowledge and experience to the forefront by actively engaging in your upcoming projects.