Electric vehicle motors are the drive motors used for electric vehicles. The form is different according to its use environment and frequency of use. The characteristics of different forms of motors are also different. Electric vehicle motors generally use permanent magnet DC motors. According to the motor's energized form and the mechanical structure of the motor assembly, it can be divided into two kinds: brush motor (motor speed is high and needs to go through gear reduction)and brushless (the output motor torque does not go through any deceleration).
Let's first get to know the composition structure of different kinds of electric vehicle motors:
It is composed of stator pole, rotor, brush, housing, etc.
The stator pole uses permanent magnets (permanent magnets), such as ferrite, Alnico, NdFeB and other materials. According to its structure, it can be divided into several types, such as cylinder type and tile type.
The rotor is generally made of silicon steel laminated, and the enameled wire is wound between the two slots of the rotor core (three slots that have three windings), and the joints are welded to the metal sheet of the commutator.
The brush is a conductive part connecting the power supply and the rotor winding, with both conductive and wear-resistant properties. The brushes of permanent magnet motor use unisex metal sheet or metal graphite brushes, electrochemical graphite brushes.
It is composed of permanent magnet rotor, multi-pole winding stator, position sensor, etc. Brushless DC motor is characterized by brushless, using semiconductor switching devices (such as Hall elements) to achieve electronic commutation, that is, electronic switching devices instead of the traditional contact commutator and brushes. It has the advantages of high reliability, no commutation spark, and low mechanical noise. As shown in Figure 1.
The position sensor switches the current of the stator winding along a certain sequence according to the change of rotor position (i.e. detects the position of the rotor pole relative to the stator winding and generates a position sensing signal at the determined position, which is processed by the signal conversion circuit to control the power switching circuit to switch the winding current according to a certain logic relationship).
It is composed of stator core, magnet rotor, sun wheel, reduction clutch, hub shell, etc.
Hall sensors can be mounted on top of the motor cover for speed measurement.
There are three types of position sensors: magnetic, photoelectric and electromagnetic.
Brushless DC motors with magnet-sensitive position sensors have magnet-sensitive sensor parts (such as Hall elements, magnet-sensitive diodes, magnet-sensitive exodes, magnet-sensitive resistors or special integrated circuits, etc.) mounted on the stator assembly to detect changes in the magnetic field generated by the permanent magnet and rotor rotation. Hall elements are mostly used in electric vehicles.
Brushless DC motor with photoelectric position sensor is equipped with a photoelectric sensor in a certain position on the stator assembly, and the rotor is equipped with a light shield, and the light source is a light-emitting diode or a small light bulb. When the rotor rotates, the photosensitive components on the stator will intermittently generate pulse signals at a certain frequency due to the role of the light shield.
Brushless DC motor with electromagnetic position sensor is equipped with electromagnetic sensor components (e.g. coupling transformer, proximity switch, LC resonance circuit, etc.) on the stator assembly. When the rotor position of the permanent magnet changes, the electromagnetic effect will cause the electromagnetic sensor to generate a high frequency modulated signal (its amplitude varies with the rotor position).
The operating voltage of the stator winding is provided by the electronic switching circuit controlled by the position sensor output.
At present, more domestic and foreign use are brushless motors, brushless DC motors are widely used in electric vehicles because it has the following two advantages compared with the traditional brush DC motors.
(1) Long life, maintenance-free and high reliability. In the brush DC motor, due to the high speed of the motor, the brushes and commutator wear faster, and generally need to replace the brushes after about 1000 hours of work. In addition, the technical difficulty of its reduction gear box, especially the lubrication of the transmission gear, is a relatively big problem in the brushed program. So the brush motor is noisy, low efficiency, prone to failure and other problems. Therefore, the advantages of brushless DC motor are obvious.
(2) High efficiency and energy saving. Generally speaking, because brushless DC motors do not have the friction loss of mechanical commutation and gear box consumption, as well as speed control circuit loss, the efficiency can usually be higher than 85%, but taking into account the actual design of the highest cost performance, in order to reduce material consumption, generally designed for 76%. And the efficiency of brushed DC motor is usually around 70% due to the consumption of gearbox and overrunning clutch.
Aiming at the "brushless DC motors and high-speed permanent magnet brushless motors" selected by domestic and foreign electric vehicle manufacturers, Nanjing Yuan Lang Electronic Technology Development Co., Ltd. independently developed, designed and produced various types of brushless electric vehicle controllers. In terms of the waveform angle includes "brushless electric vehicle square wave controller" and "brushless electric vehicle sine wave controller"; in terms of power (number of power tubes used), it can be divided into "6 tubes, 9 tubes, 12 tubes, 15 tubes, 18 tubes and 24 tubes controllers"; in terms of whether the wiring harness is matched or not, it can be divided into "conventional wired controllers and KingKong controllers". In order to maximize the matching of the controller, our Nanjing Yuan Lang Electronic Technology Development Co., Ltd. has launched a variety of products such as "dual-mode four-in-one brushless electric vehicle controller" and "dual voltage brushless electric vehicle controller". If you have any questions or needs about the brushless motor controllers, please feel free to contact us, you will get a more comprehensive and professional answer.