If you want to turn your wheel right, push with one hand while the other moves across it and pulls up. This is known as steering hand-over-hand.
CAD and FEA simulations must show the bearing and motor can withstand loads that mimic cornering, endurance and durability tests, including driving over speed bumps, embedded rock paths and other road surface features.
Torque Asymmetry
The way a wheel motor is built affects the amount of torque it can produce. There are four ways the motor can be constructed: symmetric, anti-symmetric, skew symmetric and asymmetric. There are advantages and disadvantages to each.
A symmetric motor produces the same amount of torque in both clockwise and counterclockwise rotations. This makes it easy to control speed, but can reduce efficiency and generate noise. An asymmetric motor can generate more torque in one direction but less in the other, which reduces speed, but improves efficiency and reduces noise.
An asymmetric motor is more responsive to transient conditions, such as sudden changes in acceleration or braking demand. However, it may require a higher power input to achieve the same result.
In conventional vehicles, several systems can prevent a wheel with lower road friction from spinning up when more torque is applied than the tyre-road interface can support. These include a limited-slip differential and more complex traction control systems.
An in-wheel motor does not have a transfer case or differential, which saves weight and space. It can also lose less energy to friction, which increases vehicle range and fuel economy. Moreover, it is more responsive to torque demands, so can react faster and provide advanced traction control functions. Nevertheless, it must be carefully designed to cope with the dynamic forces on its rotor, such as the cogging torque, air-gap field harmonics and stator current time-harmonics.
Inertia
Inertia is an object’s resistance to change of velocity and direction, as defined by Newton’s first law of motion: objects in motion tend to stay in motion, and objects at rest tend to remain at rest unless acted upon. The wheel motor’s inertia determines how quickly the vehicle accelerates and to what speed it can reach a given driving load.
During the design phase, FEA and CAD analyses are conducted to affirm the motor design choices. Once the rotor-bearing air gap is determined to be sufficiently stiff, thermo-mechanical simulations are performed to examine how the rotor and bearing will deform under severe heat and shock. wheel motor A limiting value is set for this deformation, ensuring that no contact between windings or permanent magnets will occur.
Once the motor is ready to undergo testing, a series of static and dynamic loads are applied. This is the beginning of a lifecycle testing process, with the goal to ensure that the motor can take repeated, harmonic and pulsating loads before components start showing signs of fatigue or degradation. These tests include simulating road-induced external loads by running the e-motor through software scenarios of driving over potholes, brick roads, speed bumps and embedded rock paths to simulate how the motor will handle these loads. Also, the rotor-bearing system is subjected to endurance and durability testing.
Relative Velocity
In pure rolling without slipping, the point of contact between wheel motor manufacturer a wheel and the ground has zero relative velocity. The point at the bottom of a wheel that is rolling without slipping has zero velocity at the instant it makes contact with the ground, and the points on either side of that contact have the same velocity (that is, they are at rest with respect to the ground).
However, once a wheel begins to accelerate, the point at the bottom of the wheel will be at the same distance from the center of rotation as the point at the top of the wheel. Thus, the linear speed v of the wheel’s point of contact is proportional to its distance from the center of rotation, and is greatest at the outermost edge of the wheel, as you would expect.
For this reason, the velocity of points on a moving wheel are determined by a combination of angular and linear speeds (or accelerations). The angular speed is the rate at which the wheel rotates around its axis. The linear speed is the rate at which the wheels moves over the ground, and is dependent on the size of the wheel.
Using a mathematical technique called vector calculus, it is possible to determine the angular and linear speeds of a point on a moving object. This method is commonly used in robotics to compute distance traveled – for example, semi-trailer trucks use odometers that count the number of wheel revolutions.
Power Distribution
In-wheel motors offer a number of benefits over traditional drivetrain systems. They reduce the number of vehicle components, simplify system architecture, and improve performance. They also allow for higher driving range and faster acceleration. In addition, they can be combined with regenerative braking to further increase efficiency. However, the system can be expensive and adds weight to the overall vehicle.
To address these issues, research on in-wheel motor torque distribution needs to expand beyond offline simulation verification. It should include a variety of constraints in actual driving conditions and more realistically simulate the working environment of the motor. This will make it possible to design more practical and efficient in-wheel motor systems.
One of the main challenges in in-wheel motor control is to distribute motor current evenly among wheels while considering the different power requirements of each wheel. This requires a complicated mathematical algorithm. The lower-level controller must be able to determine the appropriate distribution of motor torque according to the tire load rate and the utilization rate of adhesion coefficient.
To overcome this challenge, researchers have proposed a new torque distribution method. Their strategy uses a wheel-specific load scaling factor to ensure that the system is able to handle the expected loads. It also aims to reduce energy loss by optimizing the load distribution. The method has been tested using a permanent magnet synchronous motor (PMSM) model.