Introduction of brushless DC motor in power tools

With the improvement of new battery and electronic control technology, the design and manufacturing cost of brushless DC motor has been greatly reduced, and convenient rechargeable tools requiring brushless DC motor have been popularized and applied more widely. It is widely used in industrial manufacturing, assembly and maintenance industries, especially with the economic development, the demand for household is also getting higher and higher, and the annual growth rate is significantly higher than that of other industries.

2, convenient rechargeable electric tool motor application type

2.1 Brushed DC motor

Conventional brushless DC motor structure includes rotor (shaft, iron core, winding, commutator, bearing), stator (casing, magnet, end cap, etc.), carbon brush assembly, carbon brush arm and other parts.

Working principle: The stator of brushed DC motor is installed with a fixed main pole (magnet) and brush, and the rotor is installed with armature winding and commutator. The electric energy of the DC power supply enters the armature winding through the carbon brush and commutator, generating armature current. The magnetic field generated by the armature current interacts with the main magnetic field to generate electromagnetic torque, which makes the motor rotate and drive the load.

Disadvantages: Because of the existence of carbon brush and commutator, brush motor reliability is poor, failure, current instability, short life, and commutator spark will produce electromagnetic interference.

2.2 Brushless DC motor

Conventional brushless DC motor structure includes motor rotor (shaft, iron core, magnet, bearing), stator (casing, iron core, winding, sensor, end cover, etc.) and controller components.

Working principle: Brushless DC motor consists of motor body and driver, is a typical mechatronics product. The working principle is the same as that of brush motor, but the traditional commutator and carbon brush are replaced by position sensor and control line, and the direction of current is converted by control command issued by sensing signal to realize the commutation work, so as to ensure the constant electromagnetic torque and steering of the motor and make the motor rotate.

Analysis of brushless DC motor in power tools

3. Advantages and disadvantages of BLDC motor application

3.1 Advantages of BLDC motor:

3.1.1 Simple structure and reliable quality:

Cancel commutator, carbon brush, brush arm and other parts, no commutator welding, finishing process.

3.1.2 Long Service life:

The use of electronic components to replace the traditional commutator structure, eliminate the motor due to carbon brush and commutator commutator spark, mechanical wear and other problems caused by short life, motor life is increased by multiple.

3.1.3 Quiet and high efficiency:

No carbon brush and commutator structure, avoid the commutator spark and mechanical friction between carbon brush and commutator, resulting in noise, heat, motor energy loss, reduce the efficiency of the motor. Brushless DC motor efficiency in 60~70%, and brushless DC motor efficiency can achieve 75~90%

3.1.4 Wider speed regulation and control capabilities:

Precision electronic components and sensors can accurately control the output speed, torque and position of the motor, realizing intelligent and multi-functional.

Post time: May-29-2023