Model Airplane Motor

The motor has a brush and a brushless part. Structurally, the brushless motor and the brushed motor have similarities, as well as the rotor and the stator, but opposite to the structure of the brushed motor; the rotor of the brushed motor is a coil winding, connected to the power output shaft, and the stator is a permanent magnet Steel; the rotor of the brushless motor is a permanent magnet magnet, which is connected with the output shaft together with the outer casing. The stator is a winding coil, and the brush for removing the electromagnetic field by the brush motor is removed, so it is called a brushless motor ( Brushless motor).
Brush motor

A brushed motor is an electric motor that internally contains a commutating brush. The brush is fixed on the rear cover of the motor through the insulating seat, and the positive and negative poles of the power source are introduced to the commutator of the rotor, and the commutator is connected to the coil on the rotor, and the polarity of the coil is alternately changed and fixed on the outer casing. The magnet forms a force and rotates.

Brushed motor has the disadvantages of large friction, large heat generation and low efficiency due to the physical contact between the brush and the phase changer. However, the brush motor also has the advantages of simple manufacture and low cost, so the brush motor currently on the market still occupies a large share.

Brushless Motor

The brush motor is rotated by a magnetic field force in a fixed direction by a structure design of a brush and a phase changer. Brushless motors do not have brushes and commutators. How does it get the magnetic force in a fixed direction? Briefly, by changing the alternating frequency and waveform of the current wave input to the stator coil of the brushless motor, a magnetic field is formed around the winding coil that rotates around the geometric axis of the motor. This magnetic field drives the permanent magnet magnet on the rotor to rotate. The motor is turned.

The performance of the motor is related to the number of magnetic steel, the magnetic flux strength of the magnetic steel, the input voltage of the motor, etc., and has a great relationship with the control performance of the brushless motor. This is the problem that the brushless motor needs to solve the ESC.

Brushless motors have the advantages of power, long life and high efficiency. Therefore, the four-axis is made of brushless motor. The appearance of the model brushless motor is as follows. It is different from the brush motor. The most obvious is that the brushless motor has three wires and is used with the ESC.

One of the most important parameters of a brushless motor is the KV value, which is a unique performance parameter of the brushless motor and an important data for judging the performance characteristics of the brushless motor.

The KV value of the brushless motor is defined as the speed/volt, which means that the input voltage is increased by 1 volt, and the rotational speed of the brushless motor is increased (rev/min).
In view of this definition, we can know that the input of the brushless motor voltage and the motor idle speed follow a strict linear proportional relationship.
For example, a brushless motor KV value is 1000KV, which means that the motor rotates at 1000V per minute at 1V. Then at 10V, the motor speed is: 10V * 1000KV = 10000 rev / min, of course, these are when the motor is unloaded.

The number of winding turns is large, the KV value is low, and the maximum output current is small, but the torque is large.
The number of winding turns is small, the KV value is high, and the maximum output current is large, but the torque is small.
Here we can expand, why is the outer rotor brushless DC motor used in the quadcopter? The outer rotor motor makes a piece of magnetic steel that is originally in the center position and is attached to the outer casing. When the motor is running, the entire outer casing is rotating, and the middle coil stator does not move. The outer rotor brushless DC motor has a much larger moment of inertia than the inner rotor (because the main mass of the rotor is concentrated on the outer casing), so the speed is slower than that of the inner rotor motor, usually with a KV value of several hundred to several thousand. Between the use, the propeller can be directly driven on the model, and the mechanical reduction mechanism is omitted.

Hollow cup of motor

The coreless motor is a DC, permanent magnet, servo micro motor. The hollow cup motor breaks through the structure of the rotor of the conventional motor in structure, and adopts a coreless rotor. The hollow cup motor has outstanding energy saving, control and drag characteristics.

The hollow cup motor is divided into two types: brushed and brushless. The rotor of the brushed hollow cup motor has no iron core, and the stator of the brushless hollow cup motor has no iron core.

motor model

I often see what people say about 2212 motors, 2204 motors, etc. What does it mean? This is actually the size of the motor.

No matter what brand of motor, it must correspond to 4 digits of this type, the first 2 digits are the diameter of the rotor of the motor, and the second 2 digits are the height of the rotor of the motor. Note that it is not a shell. Simply put, the larger the front 2 bits, the more fat the motor, the bigger the 2nd position, the higher the motor. For example, the common 2212 motor is generally used for the 450 wheelbase aerial camera, and the 2204 motor is generally used for the 210 wheelbase crossing machine.

For hollow cup motors, the name is also two numbers of diameter and height, but generally refers to the size of the outer casing. Such as 720 motor, 615 motor and so on.