In fact, brushless motor is a kind of AC motor, a kind of three-phase AC permanent magnet motor. The current of the three wires of the input model brushless motor is AC, but this AC current is not the general 50HZ sinusoidal wave, but one modulated by the controller of the brushless motor (commonly known as brushless tuning). The frequency of a three-phase alternating rectangular wave is much higher than that of 50HZ, and it varies with the speed of the brushless motor.
Analysis of internal mechanical structure of brushless motor
Structurally, there are similarities between brushless stepper motor and brushless stepper motor, and there are also rotor and stator, but the internal structure of brushless stepper motor is opposite to that of brushless stepper motor; the rotor of brushless motor is coil winding, connected with power output axis, and the stator is permanent magnet; the rotor of brushless motor is permanent magnet steel, which is transported together with the shell. The output shaft is connected, the stator is winding coil, and the commutation brush used by brush motor to alternately transform electromagnetic field is removed, so it is called brushless motor.
Summary:
1. brush motor:
The stator is permanent magnet steel, and the rotor is coil winding, which is connected with the power output shaft.
2. brushless motor:
The stator is a coil winding, and the rotor is permanent magnet steel, which is connected with the power output shaft.
Concise operation principle of brushless motor
Simply speaking, by changing the alternating frequency and waveform of the current wave input to the stator coil of the brushless motor, a magnetic field around the winding coil is formed which revolves around the geometric axis of the motor. The magnetic field drives the permanent magnet on the rotor to rotate, and the motor turns up. The performance of the motor, the number of magnets and the flux intensity of the magnet are also discussed. The input voltage of the motor is related to the control performance of the brushless motor, because the input is DC, the current needs to be converted into 3-phase AC by electronic governor, and the control signal needs to be received from the remote controller receiver to control the speed of the motor in order to meet the needs of the model.
Generally speaking, the structure of brushless motor is relatively simple, which really determines its performance or brushless electronic governor. A good electronic governor needs the overall control of the process of single-chip computer control program design, circuit design, complex processing technology, so the price is much higher than that of brushless motor. Motor performance compares the disadvantages of brush motors.
Mould friends may wonder how to pick the fault of brushing on the first step. Ha-ha, if I tell you the following shortcomings, you will know that the fault of brushing motor is not small.
1, big friction, big loss.
Old model friends used to encounter this problem when they played with brush motor. That is, after using the motor for a period of time, they need to turn on the motor to clean the carbon brush of the motor, which is time-consuming and laborious, and the maintenance intensity is no less than a household cleaning.
2, fever and short life.
Because of the structure of brush motor, the contact resistance between brush and commutator is very large, which makes the whole resistance of brush motor bigger and easy to heat. Permanent magnet is a thermal element. If the temperature is too high, the magnet will be demagnetized, which will degrade the performance of motor and affect the life of brush motor.
3. Low efficiency and small output power.
The above mentioned heating problem of brush motor is largely due to the work done by the current on the internal resistance of the motor, so the electric energy has been converted into heat energy to a great extent, so the output power of brush motor is not large, and the efficiency is not high.
Advantages of brushless motor
1, low interference
Brushless motor removes the brush, the most direct change is that there is no spark when the brush motor is running, which greatly reduces the interference of the spark to the remote control radio equipment.
2, low noise low
Brushless motors without brushes can greatly reduce friction, run smoothly and have much lower noise. This advantage is a huge support for the stability of the model.
3, long life
Less brushes, brushless motor wear is mainly on the bearings, from a mechanical point of view, brushless motor is almost a maintenance-free motor, when necessary, just do some dust removal maintenance.
The next comparison shows that brushless motor has advantages over brushless motor, but everything is not absolute. Brushless motor is irreplaceable for its excellent low-speed torque performance and large torque. However, as for the convenience of using brushless motor, the cost of brushless controller decreases. With the development of brushless technology and market competition at home and abroad, the brushless power system is developing at a high speed and at a very important stage of popularization, which also greatly promotes the development of model movement.