Brushed motors and brushless motors operate on different principles and have different internal structures. For hub motors, the method of torque output (whether or not it's through gear reduction) differs, and their mechanical structures are also different.
1. The internal mechanical structure of common high-speed brushed motors. This type of hub motor consists of a built-in high-speed brushed motor core, a reduction gear set, an overrunning clutch, a hub end cover, and other components. High-speed brushed geared hub motors belong to the category of internal rotor motors.
2. The internal mechanical structure of commonly seen low-speed brushed motors. This type of hub motor consists of carbon brushes, a commutator, a rotor, a stator, a shaft, end covers, bearings, and other components. Low-speed brushed gearless hub motors belong to the category of external rotor motors.
3. The internal mechanical structure of common high-speed brushless motors. This type of hub motor consists of a built-in high-speed brushless motor core, planetary friction rollers, an overload clutch, an output flange, end covers, and a hub housing. High-speed brushless geared hub motors belong to the category of internal rotor motors.
4. The internal mechanical structure of common low-speed brushless motors. This type of hub motor consists of a motor rotor, motor stator, motor shaft, motor end cover, bearings, and other components. Low-speed brushless gearless hub motors belong to the category of external rotor motors.
Primary characteristics
Brushless DC motors are widely used in electric vehicles because they have the following two advantages compared to traditional brushed DC motors.
(1) Long lifespan, maintenance-free operation, and high reliability. In brushed DC motors, due to the high motor speed, the brushes and commutator wear out quickly, typically requiring brush replacement after about 1000 hours of operation. Furthermore, the reduction gearbox is technically challenging, especially the lubrication of the transmission gears, which is currently a major problem in brushed motor designs. Therefore, brushed motors suffer from issues such as high noise, low power, and susceptibility to malfunctions. Thus, the advantages of brushless DC motors are significant.
(2) High power and energy saving. Generally speaking, since brushless DC motors do not have the friction loss of mechanical commutation, the consumption of gearboxes, and the loss of speed control circuits, the power can usually be higher than 85%. However, considering the highest cost performance in practical design, in order to reduce material consumption, it is usually designed to be 76%. The power of brushed DC motors is usually around 70% due to the consumption of gearboxes and overrunning clutches.
