Views:86 Author:Site Editor Publish Time: 2021-08-21 Origin:Site
Motors have different forms according to their use environment and frequency. Different types of motors have different characteristics. Currently, permanent magnet DC motors are commonly used in electric vehicle motors. The so-called permanent magnet motor refers to the method in which the motor coil is excited by permanent magnets instead of coil excitation. This saves the electric energy consumed by the excitation coil and improves the electromechanical conversion efficiency of the motor. This can reduce the driving current and extend the driving range for electric vehicles that use limited energy on-board.
Electric vehicle motors are classified according to the energization form of the motors, which can be divided into two categories: brush motors and brushless motors; (currently, except for electric wheelchair motors, which are brush motors, all others are brushless motors)
According to the mechanical structure of the motor assembly, it is generally divided into two categories: "geared" (motor speed is high and needs to go through gear reduction) and "gearless" (motor torque output does not undergo any reduction).
According to whether there is a Hall element, it is divided into a Hall motor and a Hallless motor.
According to the installation position: divided into hub motor and mid drive motor.
Brushless gear motor
Geared motors are also called geared motors or high-speed motors. The stator speed can reach about 1200RPM. Through gear reduction (for example, the speed ratio is 1:4.4), the final motor speed is about 280RPM.
Due to cost issues, most of them use plastic gears, so there is a limit on the life, the teeth of the gears will be polished after a long time. If it is a metal gear, there is no problem, but the cost increases. The noise is slightly higher. At present, our motors are all nylon gears (nylon gear).
Advantages: The motor is small in size, light in weight, large in torque, low in operating current, and power saving. The motor has low noise.
Disadvantages: low power and slower speed.
Brushless gearless motor
Gearless motors are also called low-speed motors. The structure is simple, mainly composed of a stator, a hub and an end cover. There is no gear reduction, and the rotation speed of the stator is directly output. The general speed is 200-400RPM.
Advantages: large torque, fast speed, and power can be increased, because there is no gear system, the damage rate of the smaller motor is low.
Disadvantages: large size, heavier, slightly larger operating current, power consumption
With Hall motor and without Hall motor
With Hall motor: There are 3 position Hall sensors inside the motor. There are 8 motor outgoing wires, which are composed of 3 phase wires + 3 Hall signal wires + Hall power supply positive and negative 2 wires. Since 2013, the speed sensor has been built into the motor, so the current Hall motor has 9 cores.
Hallless motor: There are only 3 phase wires for the motor outlet. If there is an in-band speed sensor, there are 6 outgoing wires (3 phase wires + 1 speed hall signal wire + 2 hall power supply positive and negative poles
Note: Hall motors must be matched with Hall controllers. The non-Hall motor must be matched with the non-Hall controller. At present, there are also dual-mode controllers, which can be matched with Hall motors or without Hall motors.
Advantages of no Hall motor:
1. Longer life and reliability, because no Hall can be damaged;
2. Low cost because no Hall is needed
3. It is easier to manufacture, without welding Hall;
Disadvantages of no Hall motor:
1. Start is not smooth, because there is no Hall to detect the rotor position, so the drive part needs to do zero-crossing current detection, which causes the motor to vibrate when starting, or even fail to start
2. Not suitable for applications with large loads or large changes in load
There are advantages of Hall motor:
Equipped with a Hall sensor inside, it can detect the position of the rotor and start smoothly.
The motor can be started at zero speed thanks to the Hall sensor.
There are disadvantages of Hall motor:
The price is higher than without Hall
The structure is more complex than without Hall
The service life of the motor is generally 5-10 years, and it is generally not easy to be damaged under normal use.
The most easily damaged part of a Hall motor is the Hall element. Next is the nylon wheel, but the material used for the nylon wheel is getting better and better, so don't worry too much about the damage of the nylon wheel.
When in use, it should be accelerated slowly to avoid sudden acceleration and damage to the components. When the vehicle starts and climbs uphill, the pedals are used to assist or push with force.