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Ten reasons why electric motors vibrate

1. Imbalance of rotor, coupler, coupling and transmission wheel (brake wheel).
2. Loose core support, loose oblique key and pin failure, and loose rotor binding will cause imbalance of the rotating part.
3. The axis of the linkage part is out of center, the center line does not coincide, and the centering is not correct.The main cause of this kind of failure is the installation process, poor and improper installation.
4. The center line of the linkage part overlaps and is consistent in the cold state, but after running for a period of time, the center line is damaged due to the deformation of the rotor fulcrum and foundation, resulting in vibration.
5. The gear and coupling connected with the motor are out of order, with poor occlusion of the gear, severe wear of the gear teeth, poor lubrication of the opposite wheel, misalignment of the coupling, wrong tooth shape and tooth spacing, excessive clearance or severe wear, all of which will cause certain vibration.
6. Defects in the motor structure itself, including ellipse of shaft neck, bending of rotating shaft, excessive or too small gap between shaft and bearing bush, and insufficient stiffness of bearing seat, foundation plate, part of foundation and even the entire motor installation foundation.
7. Installation problems: the motor is not firmly fixed between the base plate, the foot bolt is loose, and the bearing seat is loose between the base plate, etc.
8. Too large or too small clearance between shaft and bearing bush can not only cause vibration but also abnormal lubrication and temperature of bearing bush.
9. Load conduction vibration of motor drag, such as vibration of fan and water pump dragged by motor, causes motor vibration.
10. Ac motor stator wiring error, rotor winding short-circuit wound linear asynchronous motor, synchronous motor winding inter-turn short-circuit, synchronous motor excitation coil connection error, cage asynchronous motor rotor bar broken, rotor core deformation caused by stator and rotor air gap uneven, resulting in air gap flux imbalance resulting in vibration.

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The general tests of electric motors：2

2. Determination of dc resistance of winding: 1) Significance of dc resistance measurement: The dc resistance of the windings in cold state is one of the main parameters of three-phase asynchronous motors. By comparing the measured value of the resistance of the windings with the design value, it is possible to check whether the windings have broken wires and short-circuit between turns, whether the welding parts have virtual welding or open welding, whether the contact points have bad contact and other phenomena. 2) Dc resistance measurement method: Measuring the dc resistance of the motor should be done when the winding is cold. First, place the motor indoors for a period of time, and measure the temperature of the motor winding end or core with a thermometer. At this time, the measured temperature is the actual temperature of the winding in the cold state. If the temperature of the winding end or core cannot be measured, the temperature of the housing may be substituted
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Comparison of structure motor with internal rotor and external rotor

In general, the stator of the motor is on the outside and the rotor is on the inside. In a conventional brush dc motor, the stator field is on the outside and the rotor armature is on the inside. Brushless dc motor appeared, so that the rotating armature from the inside to the outside, from the rotor into a stator; And the original stationary stator permanent magnet went inside, and from the stator become the rotor. This kind of structure is called an "internal rotor structure". In practical use, sometimes in order to meet the special technical requirements of some electromechanical, the motor stator armature is made inside, and the rotor with permanent magnet is made outside. We call this structure "external rotor structure", or "internal stator structure". In the design of brushless dc motor, the external rotor structure and the internal rotor structure have their own advantages and disadvantages. The differences in motor characteristics between the
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Traction motor for electric vehicle： induction motor, permanent magnet motor, who is the future direction?

In the era of fuel cars, we often hear the battle between natural inspirations and turbocharged engines. And in the era of electric cars, there is also a clear debate between electric motors. After the test of the market, there are two kinds of mainstream electric motors on the market at present, one is induction motor (also known as asynchronous ac motor), the other is permanent magnet motor. Induction motor is a kind of motor which has the rotor rotation powered by magnetic torque created by the physical interaction of stator winding magentic field and the induction current generated rotor magnetic field. Tesla Model S and Model X are representatives of induction motor applications. The permanent magnet motor mainly refers to the permanent magnet synchronous motor, and the biggest difference with the induction motor in structure is that the rotor is permanent magnet structure, rather than wound by the electric coil. Which is better, the induction motor or the permanent mag
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