Comparison of brushed motor and brushless motor
The difference between the brushing motor and the brushless motor is that the brush motor is mechanically commutated by the carbon brush and the commutator, and the brushless motor is electronically commutated by the controller by the Hall element sensing signal. Brushed motors and brushless motors have different energization principles and their internal structures are different. For the hub type motor, the output mode of the motor torque (whether it is decelerated by the gear reduction mechanism) is different, and the mechanical structure is also different.
1. The internal mechanical structure of common high speed brushed motors. The hub type motor is composed of a built-in high speed brush motor core, a reduction gear set, an overrunning clutch, a hub end cover and the like. The high speed brushed geared hub motor belongs to the inner rotor motor.
2. The internal mechanical structure of common low speed brushed motors. The hub type motor is composed of a carbon brush, a phase changer, a motor rotor, a motor stator, a motor shaft, a motor end cover, a bearing and the like. The low speed brushless gearless hub motor belongs to the outer rotor motor.
3. The internal mechanical structure of common high speed brushless motors. The hub type motor is composed of a built-in high speed brushless motor core, a planetary friction roller, an overload clutch, an output flange, an end cover, a hub shell and the like. The high speed brushless geared hub motor is an inner rotor motor.
4. The internal mechanical structure of common low-speed brushless motors. The hub type motor is composed of a motor rotor, a motor stator, a motor shaft, a motor end cover, a bearing and the like. The low speed brushless gearless hub motor belongs to the outer rotor motor.
Main characteristics
Brushless DC motors are widely used in electric vehicles because they have the following two advantages over conventional brushed DC motors.
(1) Long life, maintenance-free, and high reliability. In the brushed DC motor, the brush and the commutator wear faster because of the higher motor speed, and the brush needs to be replaced after about 1000 hours of work. In addition, the technical difficulty of the reduction gear box is relatively large, especially the lubrication problem of the transmission gear, which is a relatively large problem in the current brush scheme. Therefore, there are problems such as large noise, low efficiency, and easy failure. Therefore, the advantages of brushless DC motors are obvious.
(2) High efficiency and energy saving. In general, because brushless DC motors have no mechanical commutation friction loss and gearbox consumption, as well as speed control circuit losses, the efficiency is usually higher than 85%, but in view of the most cost-effective design in the actual design, to reduce material consumption. The general design is 76%. The efficiency of brushed DC motors is typically around 70% due to the consumption of gearboxes and overrunning clutches.
working principle
An electric motor is a device that converts electrical energy into mechanical energy. It uses a energized coil (that is, a stator winding) to generate a rotating magnetic field and acts on a rotor squirrel-cage closed aluminum frame to form a magnetoelectric rotational torque. The electric motor is divided into a direct current motor and an alternating current motor according to the use of the power source. The electric motor in the electric power system is mostly an alternating current motor, and may be a synchronous motor or an asynchronous motor (the stator magnetic field speed of the motor and the rotational speed of the rotor are not kept at the synchronous speed). The motor is mainly composed of a stator and a rotor, and the direction in which the energized wire is subjected to the force in the magnetic field is related to the direction of the current and the direction of the magnetic induction line (the direction of the magnetic field). The working principle of the motor is that the magnetic field acts on the current to force the motor to rotate.
basic introduction
An electric motor is a rotary electric machine that converts electrical energy into mechanical energy. It mainly includes an electromagnet winding or distributed stator winding for generating a magnetic field and a rotating armature or rotor. Under the action of the rotating magnetic field of the stator winding, it has a current passing through the armature squirrel cage aluminum frame and is rotated by the action of the magnetic field. Some of these machines can be used as motors or as generators. It is a machine that converts electrical energy into mechanical energy. Usually, the work part of the motor is rotated. This type of motor is called a rotor motor; it is also called a linear motor.
