The electric vehicle motor has different forms depending on the environment in which it is used and the frequency of use. Different types of motors have different characteristics. Permanent magnet DC motors are commonly used in electric vehicle motors. The so-called permanent magnet motor means that the motor coil is excited by a permanent magnet, and the coil is not excited. This saves the electric energy consumed during the operation of the excitation coil and improves the electromechanical conversion efficiency of the motor. This can reduce the running current and extend the mileage of the electric vehicle using the limited energy of the vehicle.
Electric motor motor is divided into two categories according to the power-on form of the motor. It can be divided into two types: brush motor and brushless motor. According to the mechanical structure of the motor assembly, it is generally divided into “toothed†(high motor speed, need to go through the gear Deceleration) and "no teeth" (motor torque output does not undergo any deceleration) two categories. 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.
Composition
1. Permanent magnet DC motor:
It consists of a stator pole, a rotor, a brush, a casing, and the like.
The stator poles are made of permanent magnets (permanent magnets) and are made of ferrite, aluminium-nickel-cobalt, neodymium-iron-boron or the like. According to its structural form, it can be divided into cylindrical type and tile type.
The rotor is generally laminated with silicon steel sheets, and the enameled wire is wound between the two slots of the rotor core (three slots have three windings), and the joints are respectively welded to the metal piece of the commutator.
The brush is a conductive component that connects the power supply to the rotor winding, and has both electrical and wear resistance properties. The brush of the permanent magnet motor uses a single metal sheet or a metal graphite brush or an electrochemical graphite brush.
2. Brushless DC motor:
It consists of a permanent magnet rotor, a multi-pole winding stator, a position sensor, and the like. Brushless DC motors are characterized by brushless, semiconductor switching devices (such as Hall elements) for electronic commutation, that is, electronic switching devices replace traditional contact commutators and brushes. It has the advantages of high reliability, no commutation spark, and low mechanical noise.
The position sensor commutates the current of the stator winding in a certain order according to the change of the rotor position (ie, 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. Control the power switch circuit to switch the winding current according to a certain logic relationship)
3. High speed permanent magnet brushless motor:
It consists of a stator core, a magnetic steel rotor, a sun gear, a deceleration clutch, and a hub shell.
A Hall sensor can be mounted on the motor cover for speed measurement.
Position sensors are available in magnetic, photoelectric and electromagnetic types.
A brushless DC motor using a magnetically sensitive position sensor, the magnetic sensing element (such as a Hall element, a magnetic sensitive diode, a magnetically sensitive diode, a magnetoresistor or an ASIC) is mounted on the stator assembly. To detect the change of the magnetic field generated when the permanent magnet and the rotor rotate. Multi-purpose electric vehicles are Hall elements.
A brushless DC motor using a photoelectric position sensor is provided with a photoelectric sensor device at a certain position on the stator assembly, and a light shielding plate is mounted on the rotor, 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 action of the visor.
A brushless DC motor using an electromagnetic position sensor is provided with an electromagnetic sensor component (for example, a coupling transformer, a proximity switch, an LC resonance circuit, etc.) on the stator assembly. When the position of the permanent magnet rotor changes, the electromagnetic effect will cause the electromagnetic sensor. A high frequency modulated signal is generated (the amplitude of which varies with rotor position).
The operating voltage of the stator windings is provided by an electronic switching circuit controlled by the position sensor output.
Equipment classification
The drive motor for electric vehicles is different from conventional industrial motors. The drive motor of an electric vehicle usually requires frequent start/stop, acceleration/deceleration, high torque required for low speed or climbing, low torque required for high speed running, and large shift range. Industrial motors are usually optimized at the rated operating point. Therefore, electric vehicle drive motors are unique and should be classified separately.
For the brushless motor, according to whether the motor has a position sensor, it is further divided into a position sensor brushless motor and a position sensorless brushless motor. For brushless motors without position sensor, the car must be lifted first. After the motor has a certain rotation speed, the controller can recognize the phase of the brushless motor, and then the controller can supply power to the motor. Since the position sensorless brushless motor cannot achieve zero speed start, it is used less on electric vehicles produced after 2000. For brushless motors used in the electric vehicle industry, position sensor brushless motors are commonly used. Rotating 180°, the coil does not move, the Hall element senses the S-pole magnetic field. At this time, P1 and R2 are cut off, and P2 and R1 are turned on. It can be seen that the current i' flows from the positive electrode of the battery through R1, coil and P2 to the negative pole of the battery. The current i' direction of point A in the energized coil is the direction pointing to the terminal (the vector direction is opposite to the i' vector direction), and the magnetic steel is subjected to the reaction force of the coil, and the rotational torque in the counterclockwise direction is generated. The number of magnetic steels for brushless motors for electric vehicles is relatively large. There are generally three sets of coils. Each set of coils has a corresponding Hall element (three phase coils have three Hall elements), so that the motor rotates more smoothly and efficiently. higher. When the magnetic steel rotates, the Hall element senses the change of the magnetic field direction and gives a corresponding control signal, and the brushless controller controls the conduction and the cut-off of the upper 3 and lower 3 power tubes according to the signal.
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.
OLED is organic light-emitting diode (D1de), which has the characteristics of self illumination, high brightness, wide viewing angle, high contrast, flexibility, low energy consumption and so on. Therefore, it has been widely concerned. As a new generation of display mode, it has gradually replaced the traditional liquid crystal display, and is widely used in mobile phone screen, computer display, full-color TV and so on. OLED display technology is different from traditional liquid crystal display technology. It does not need backlight. It uses very thin organic material coating and glass substrate. When there is current passing through, these organic materials will emit light. However, as organic materials are easy to react with water vapor or oxygen, OLED displays have high requirements for packaging.
Package Locating OLED Cover Glass,High Precision OLED Cover Glass,Special Desiccant Installed OLED Cover Glass
SHAOXING HUALI ELECTRONICS CO., LTD. , https://www.cnsxhuali.com