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.
