Driving system: Basic knowledge of drones (structural editions) 5 | Mono making & town development BtoB information site "Tech Note"

Last time, I explained the rotor, the main part of the drone.This time, I will explain the drive system, which is an important part of raising and flying drones.The drive system is a system that conveys the output of the engine, which is basically composed of a motor and a part calledEsc that controls it.In drones, these two are the main components of the drive system.

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1.motor

A motor is a general term for devices that convert electric energy into mechanical energy.Motors are classified as brushimoters and brushless motors (Fig. 1).For general drones, brushless motors are used.Brushless motor requires a driving circuit.

・ Brashimotor brushimotor is a motor with two lines and is used for models and small toy drones.An electrode called a brush is provided inside the motor and a rectifier called a community, and the two are mechanically switched to rotate the motor.The speed change is performed in a way called PWM (Pulse Width Modulation).

・ Brushless motor brushless motor is a motor with three lines and rotates using a special drive circuit.The brush motor is equipped with a rectifier circuit by removing the mechanical contact parts such as the brush required for the brush motor and the rectifier, so it is excellent in energy efficiency.It is also possible to change the rotation direction by the signal.However, since the drone can only rotate in one direction, no control in the rotation direction is performed.

When using a drone or airplane brushless motor, the part that fixes the rotor and propeller (FIG. 2) is determined by the right knob or left knob according to the rotation direction of the motor, and does not rotate in the specified direction.The screw is loose.When purchasing, check the notation of CW (clock) and CCW (counterclockwise) and select with care.In the case of a quad (4 sheets) rotor type, a total of 4 motors are required for CW x 2 + CCW x 2.

Brushless motor is a type of three -phase motor, an exchange motor.For this reason, it is necessary to add an exchange (three -phase exchange) to rotate.At this time, the three -phase exchange is theEsc (Electric Speed Controller) described in the following section.Of course, you need to selectEsc according to the current consumed by the motor.

Drones that use brushless motors are often directly connected to motors and rotors.Some drones connect the motor and the rotor via the gear.

Let's look at the structure of the motor.Figure 3 shows a motor disassembled.The left part is called a rotor (Note: different from the feather rotor) in the rotating part.The part on the right is a fixed part inside the rotor, and is called a status.This type of motor is called outer rotor or outrunner because the outer part rotates, and is often used in drones and airplanes.There is a permanent magnet inside the rotor, and the status has a winding, and it rotates by flowing current into the winding line.

In addition, there is something called KV value in the motor, which indicates how many rotations perV (but no load).Since the motor in Fig. 3 is 1,100kV, it rotates 1,100 rotations (RPM) with a 1V voltage.In the case of a drone, the KV value used is determined by the size and weight of the aircraft, so select the Motor of the KV value according to the aircraft.

2.Esc

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