1. Definition

Brushless motor refers to the motor without brush and commutator (or collector ring), also known as the non-commutator motor, which is composed of the main body of the motor and the driver. The brushless motor uses a transistor electronic commutation circuit to replace the brush and commutator mechanical commutation device to change the current direction, which overcomes the shortcomings of the short life of the traditional brush motor carbon brush. The permanent magnets of brushless DC motors are now mostly made of rare earth neodymium iron boron (Nd-Fe-B) materials with high magnetic energy levels. Therefore, the volume of the rare earth permanent magnet brushless motor is reduced by one frame size compared with the same capacity asynchronous motor.

2. Characteristics

1. It can replace brush motor speed regulation, frequency converter + frequency conversion motor speed regulation, asynchronous motor + speed reducer speed regulation;

2. It has the advantages of the traditional DC motor, and the carbon brush and slip ring structure are eliminated;

3. It can run at low speed and high power, and can save the reducer to directly drive a large load;

4. Small size, light weight and large output;

5. Excellent torque characteristics, good torque performance at medium and low speeds, large starting torque and small starting current;

6. Stepless speed regulation, wide speed regulation range, strong overload capacity;

7. Soft start and stop, good braking characteristics, can save the original mechanical brake or electromagnetic brake device;

8. High efficiency, the motor itself has no excitation loss and carbon brush loss, eliminating multi-stage deceleration consumption, and the comprehensive power saving rate can reach 20% ~ 60%.

9. High reliability, good stability, strong adaptability, simple repair and maintenance;

10. Resistant to bumpy vibration, low noise, small vibration, smooth operation and long life;

11. No sparks, especially suitable for explosive places, with explosion-proof type;

12. Trapezoidal wave magnetic field motor and sine wave magnetic field motor can be selected as required.

3. Application

Based on the above characteristics, brushless motors are widely used in various intelligent and automated applications, such as soft and hard disk drives, motorcycles, blowers, water pumps, aircraft models, household appliances, office automation, medical equipment, automobiles, etc.

4. Construction of Brushless motorSocial responsibility

The structure of brushless DC motor is mainly composed of three parts: motor body, position sensor and electronic switch circuit. The motor body is similar in structure to a permanent magnet synchronous motor, but without cage windings and other starting devices. The stator windings are generally made of multiple phases (three-phase, four-phase, no phase...), and the rotor is composed of permanent magnetic steel according to a certain number of pole pairs (2p = 2, 4, ...).

The main body of brushless DC motor is composed of permanent magnet rotor, multi-pole winding stator, position sensor and so on. The position sensor converts the current of the stator winding along a certain order according to the change of the rotor position (that is, detects the position of the rotor magnetic pole relative to the stator winding, and generates a position sensor signal at the determined position, which is processed by the signal conversion circuit To control the power switch circuit, switch the winding current according to a certain logical relationship). The working voltage of the stator winding is provided by the electronic switch circuit controlled by the output of the position sensor.

There are three types of position sensor: magnetic sensitive type, photoelectric type and electromagnetic type.

The brushless DC motor using a magnetosensitive position sensor, the magnetosensitive sensor device (such as Hall element, magnetodiode, magnetosensitive tube, magnetoresistor or special integrated circuit, etc.) is installed on the stator assembly, used to detect the change of the magnetic field generated when the permanent magnet and the rotor rotate.

A brushless DC motor with a photoelectric position sensor is equipped with a photoelectric sensor device at a certain position on the stator assembly. The rotor is equipped with a shading plate and the light source is a light-emitting diode or a small light bulb. When the rotor rotates, due to the effect of the shading plate, the photosensitive components on the stator will generate pulse signals intermittently at a certain frequency.

The brushless DC motor with electromagnetic position sensor is equipped with electromagnetic sensor components (such as coupling transformer, proximity switch, LC resonance circuit, etc.) on the stator assembly. When the position of the permanent magnet rotor changes, the electromagnetic effect will make the electromagnetic sensor Generate high frequency modulation signal (its amplitude changes with rotor position)

5. Working of Brushless motor

As we all know, the stator of a general permanent magnet DC motor is composed of permanent magnetic steel, and its main role is to generate a magnetic field in the air gap of the motor. The energized armature winding generates a reactive magnetic field. The energized armature winding generates a reactive magnetic field. Due to the commutation effect of the brushes, the directions of the two magnetic fields are always kept perpendicular to each other during the operation of the DC motor, thereby generating maximum torque and driving the motor to run continuously. In order to realize the brushless commutation of the DC brushless motor, the armature winding of the general DC motor is required to be placed on the stator, and the permanent magnet steel is placed on the rotor. But this is not enough, because the general DC power supply to the stator windings can only generate a fixed magnetic field, it can not interact with the permanent magnet magnetic field generated by the rotor magnet in motion to produce a single direction of torque To drive the rotor to rotate. Therefore, in addition to the stator and rotor composed of the motor body, the DC brushless motor also needs a commutation device composed of a position sensor, a control circuit, and a power logic switch, so that the stator winding generated by the brushless DC motor during operation The magnetic field and the permanent magnetic field generated by the rotating rotor magnet are always maintained at an electrical angle of (π / 2) rad in space.

6. General Characteristics

7. Naming rule

1. The Brushless motor is denoted by "BL"
2. It is expressed by the maximum outside diameter of the motor lamination
3. To the motor lamination stacked thickness value    
4. "I" stands for inner rotor,"0" stands for external rotor
5. "D" indicates that DC voltage is used, "A" indicates that AC voltage is used
6. 012 represents the rated voltage of 12V