Electric wheel drive technology
As an independent driving component, the electric wheel integrates the electric motor, transmission mechanism, brake and other components into the wheel hub, making it a unique driving unit.
Electric vehicles with electric wheel drive eliminate the traditional mechanical differential, requiring the adjustment of the rotational speeds on both sides to achieve the differential function when turning.
In traditional vehicles, the left and right wheels are connected by a mechanical steering trapezoid. On a generally good road surface, the torques generated around the kingpin by the driving forces of the left and right steering wheels are roughly equal in magnitude and opposite in direction, thus canceling each other out.
In electric drive vehicles, because the torque of each wheel is independently controllable, the driving force of the left and right steering wheels can be unequal when turning. The torque of the driving forces about the kingpin axis will no longer cancel each other out, meaning the driving steering torque is no longer zero. Since the two steering wheels are connected by a steering trapezoid, the driving steering torque will drive both steering wheels to turn.
Therefore, for electric wheel-driven vehicles, while ensuring stable straight-line driving, theoretically, by controlling the output torque of the left and right steering wheels in real time according to certain rules, the generated driving steering torque can be used to achieve power steering.
Introduction to Electric Wheel Drive Technology
Electric wheel drive technology uses four or more independently controlled electric wheels to provide driving torque to each of the vehicle's wheels. There is no mechanical transmission link between the power source and the wheels. A typical electric wheel structure is shown in Figure 7-1.
Figure 7-1 Typical electric wheel structure
(1) Structural forms and characteristics of electric wheel drive power systems Electric wheel drive power systems are mainly divided into two structural forms: one is an electric wheel system based on an internal rotor type motor; the other is an electric wheel system based on an external rotor type motor. Figure 7-2 shows the structural diagrams of these two electric wheel systems. In Figure (a), the rotor is inside the permanent magnet; in Figure (b), the rotor is outside the permanent magnet.
Figure 7-2 Simplified diagram of electric wheel system: 1—Tire; 2—Rim; 3—Brake; 4—Stator winding; 5—Permanent magnet; 6—Rotor; 7—Motor controller; 8—Reduction gear; 9—Bearing
Currently, electric wheel systems based on internal rotor motors employ high-speed, low-torque motors. To meet the actual wheel speed requirements, a corresponding planetary gear reduction mechanism is typically required. Electric wheel systems based on external rotor motors, on the other hand, use low-speed, high-torque motors. Since their speed range matches the actual wheel speed requirements, a reduction mechanism is usually unnecessary, and the wheels are directly driven by the external rotor of the motor. A typical electric wheel system arrangement is shown in Figure 7-3. The four electric wheels act as independent drive elements to propel the vehicle.
Figure 7-3 Arrangement of electric wheel system
Disclaimer: This article is a reprint. If it involves copyright issues, please contact us promptly for deletion (QQ: 2737591964 ) . We apologize for any inconvenience.
