What factors affect the loss of the hub motor?

As users of hub motors, we definitely hope that the efficiency of hub motors can be maximized, and in the process of running hub motors, losses will inevitably occur. If we want to improve efficiency, we must first understand what it is Energy is lost in the motor.
1. Iron consumption
Iron loss is the loss of the motor core and end iron parts. Mainly divided into "hysteresis loss" and "eddy current loss".
1) Hysteresis loss
The magnetic flux in the transformer is active on the iron core. The iron core has a magnetic resistance to the magnetic flux, just like a conductor has a resistance to the current, and it will also generate heat. We call this loss "hysteresis loss". In order to reduce the effect of hysteresis loss and the associated energy loss, ferromagnetic substances with low coercive force and low hysteresis loss, such as permalloy, are used.
2) Eddy current loss
Because the iron core itself is also a conductor, an electric potential will be induced on a plane perpendicular to the magnetic force line, and this electric potential forms a closed loop on the cross section of the iron core and generates a current, as if a vortex is called "eddy current". This "eddy current" increases the loss of the transformer and increases the temperature rise of the transformer's core heating transformer. Generally, the eddy current loss is much greater than the hysteresis loss.
2. Copper consumption
Copper loss has two loss modes, the power loss of the stator winding and the power loss of the rotor winding. Due to the resistance in the stator and rotor windings, electric energy loss will be generated when the current passes, which is called copper loss. The size of the copper loss is proportional to the square of the current through the hub motor. Copper loss is the most "arrogant" among all the losses of the motor. They don't need to be hidden, so it is very easy to calculate. It is only related to the current and the resistance of the winding. When the current is passed into the winding, it will desperately absorb it. , and the current is related to the motor torque.
3. Mechanical loss
The types of mechanical losses are quite complicated. No matter what state the hub motor is running in, the mechanical loss can account for at least 20% of the total loss of the hub motor. Mainly divided into "wind friction loss" and "stray loss".
1) Wind friction loss
Wind friction is bearing friction and ventilation loss. It corresponds to the power consumed by bearing friction and ventilation resistance, and its magnitude is related to the roughness of the rotor surface and the rotational speed. The mechanism of its generation is very simple. When the rotor of the motor rotates, due to the existence of air resistance, it appears, and the faster it rotates, the stronger it is.
2) Stray loss
When the stator winding is fed with current, a certain amount of copper loss will be generated. For most motors, the "flow" of the stator and rotor windings is alternating current. For some rotors without windings (permanent magnets), it is ignored. The current of alternating current The size and direction change. The so-called changing current produces a changing magnetic field. When the speed of the motor rises and the frequency of the current rises to a certain level, the central area of the winding wire will generate a huge induced electromotive force. Because the central area of the wire has a closed The existence of the loop will lead to the generation of induced current. The induced current is always opposite to the other, and it always hinders the change of the original current. Therefore, a blockage area will be formed in the central part of the wire cross section, and the trajectory of the current flow will tend to The outer part of the wire section is the legendary "skin effect". The result of the "skin effect" is that the cross-sectional area of the wire is reduced, the resistance of the wire is increased, and the energy loss of the AC current running through the winding wire has an additional bonus. Cheng" is the stray loss. The size of the stray loss can be determined by the loss analysis method of the motor test.
The above is the analysis of which factors affect the loss of the hub motor. It can be known that the hub motor is mainly affected by the three major factors of iron loss, copper loss and mechanical loss. Usually, the measures to reduce these losses are through the production process and the hub motor. Adjust the material to reduce the value of each loss, so that the hub motor meets the standard requirements.