Questions and answers about basic motor knowledge(Two)

26/06/2019

★ What is a brush motor?
Answer: When the motor is working, the coil and the commutator rotate, the magnetic steel and the carbon brush do not rotate, and the alternating current direction of the coil is completed by the commutator and the brush that rotate with the motor. Brush motors in the electric vehicle industry are divided into high speed brush motors and low speed brush motors. There are many differences between brush motor and brushless motor. It can be seen from the word that the brush motor has a carbon brush, and the brushless motor has no carbon brush.

★ What is a low speed brush motor? What are the characteristics?
Answer: In the electric vehicle industry, the low-speed brush motor refers to the hub-type low-speed high-torque gearless transmission brushed DC motor. The relative speed of the stator and rotor of the motor is the speed of the wheel. The number of magnetic steels on the stator is 5~7 pairs, and the number of slots of the rotor armature is 39~57. Since the armature winding is fixed in the wheel housing, heat is easily dissipated by means of the rotating housing. The rotating outer casing is woven with 36 spokes, which is more favorable for heat conduction.

★The characteristics of brushed toothed motor?
Answer: Because there is a brush in the brush motor, the main hidden danger is “brush wear”. Users should notice that the brush motor is divided into two types: toothed and toothless. At present, many manufacturers choose brushed toothed motors, which are high-speed motors. The so-called "toothed" is to reduce the motor speed through the gear reduction mechanism. (The speed of the electric vehicle must not exceed 20 kilometers due to the national standard, so the motor speed should be 170 rpm / per minute). Because the high-speed motor is decelerated by the gear, it is characterized by the rider feeling strong power at the start, and the climbing ability is strong. However, the electric wheel hub is closed, but the lubricant is added before leaving the factory. It is difficult for the user to carry out daily maintenance, and the gear itself also has mechanical wear. The gear wear is increased due to insufficient lubrication for a year or so, the noise is increased, and the current is also used. Increase, affecting motor and battery life.

★ What is a brushless motor?
Since the controller provides direct current in different current directions, the alternating current direction of the coil inside the motor is achieved. There are no brushes and commutators between the rotor and the stator of the brushless motor.

★How does the motor achieve commutation?
Answer: When the brushless or brushed motor is rotating, the energizing direction of the coil inside the motor needs to be alternately changed, so that the motor can continuously rotate. The commutation of the brushed motor is done by the commutator and the brush, and the brushless motor is completed by the controller.

★ What is the lack of phase?
A: One phase of the three-phase circuit of the brushless motor or the brushless controller cannot work. The lack of phase division main phase phase loss and Hall phase loss. It is manifested that the motor shake can not work, or the rotation is weak and the noise is loud. The controller works easily in the phase loss state and is easily burned.

★What are the common types of motors?
Answer: Common motors include: brushed hub motor, brushless gear hub motor, brushless gear hub motor, brushless gearless hub motor, side-mounted motor, etc.

★How do you distinguish between high and low speed motors from the type of motor?
Answer: A brushed hub motor, brushless gear hub motor is a high speed motor;
B Brushless gearless hub motor, brushless gearless hub motor is a low speed motor.

★ How is the power of the motor defined?
Answer: The power of the motor refers to the ratio of the mechanical energy output by the motor to the power supplied by the power supply.

★ Why choose the power of the motor? What is the significance of choosing motor power?
A: The choice of rated motor power is a very important and complicated issue. When the load is too high, if the rated power of the motor is too large, the motor will often be in light load operation, and the capacity of the motor itself will not be fully exerted, and it will become a “large horse-drawn car”. At the same time, the motor has low operating efficiency and poor performance, which will increase. Operating expenses. Conversely, the rated power of the motor is small, that is, the "small horse-drawn cart", the motor current exceeds the rated current, the loss in the motor is increased, and the efficiency is low, the important thing is to affect the life of the motor, even if the overload is not much The life of the motor will also be reduced more; the overload will destroy the insulation performance of the motor insulation material and even burn it. Of course, the rated power of the motor is small, and the load may not be dragged at all, which will cause the motor to be used for a long time.
It is overheated and damaged in the startup state. Therefore, the rated power of the motor should be selected in strict accordance with the operation of the electric vehicle.