DC motor is a motor that can transform DC electric energy into mechanical energy, and it can be divided into the brushed DC motor and the brushless DC motor.
A brushed DC motor consists of a stator (the static part), a rotor (the rotating part), and a brush. There are magnetic poles on the stator and windings on the rotor. After electrifying, a magnetic pole is formed on the rotor, and there is an included angle between the magnetic pole of the rotor and stator. Under mutual attractions of the stator and the magnetic pole of the rotor, the motor rotates.
We know that the coil portion of the brushed motor rotates. The brush is used to make contact with the commutator (copper head) in the winding for the coil to contact electricity and change the direction. The brush can be worn during rotation, therefore the brush of the brushed DC motor needs to be replaced after it is worn out.
Because the commutator can be worn during use, the copper head needs polishing to keep smooth, and the contact area of the brush and copper head needs to be expanded to improve efficiency. In a word, maintaining a brushed DC motor is quite troublesome.
The brushed motor isn’t commonly used in multi-axis aircraft, while a coreless brush motor is used in some light four-axis device sometimes. The rotor of a traditional motor is formed by winding coils in an iron core, and the rotor of a coreless motor consists of a cage woven of coils without iron core, which has the characteristics of light weight (no iron core), quick response due to large rotating inertia and energy conversion.
The shortcomings of brushed DC motor:
A. The friction between the brush and the commutator causes low efficiency, loud noise, heating up, and short service life which is several times shorter than that of a brushless gear motor.
B. The brush needs to be changed regularly.
C.Low efficiency and output power for high resistance
D. High interference since the friction between brush and commutator can cause sparks
The characteristics of the brushed motor:
A.Good performance and high torque
B. The prices are lower than that of a brushless motor
C. Due to the lack of electronic parts, no influence of sensor interference.
The coil part of the brushless gear motor is static, and the rotating part is a rotor that contains a magnet.
In this situation, three groups of coil and brushless electric modulation is required to generate varying magnetic fields by continuously changing the current direction of coils, and drive the magnet rotor to rotate constantly. A Brushless motor needs brushless electric modulation to work, while a brush motor can rotate by connecting the wire to the positive or negative of the power supply.
The shortcomings of the brushless motor
A.Brushless electric modulation is required to work together, so the price is higher than that of the brush motor
B.The reliability is influenced by electronic parts. The motor will fail to rotate when the sensor is disturbed.
The characteristics of the brushless motor:
A. No friction between brush and commutator, low noise, small vibration, less heat generating, long service life
B. No need to change brush, easy to maintain
C. No sparks caused by brush, less interference.
D. High torque, good performance at medium and low speed, high starting torque, and small starting current.
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